This document presents a computational fluid dynamics (CFD) model to study the effects of carbon deposit from methane gas on Zeolite Y catalyst activity in a packed bed reactor. The model considers two cases - the influence of carbon deposition on catalyst activity, and the effect of carbon deposits on fluid flow over time and space. The CFD model is developed using Comsol Multiphysics software and simulates methane decomposition in the packed bed reactor, accounting for reactions, fluid flow, heat transfer, and carbon deposition over time. Results from the first model show increases in hydrogen production and carbon deposition over time, indicating methane decomposition is occurring as well as catalyst deactivation from carbon.
This document describes a computational fluid dynamics (CFD) study of methane decomposition into hydrogen and solid carbon in a packed bed fluid catalytic cracking (FCC) reactor. The study used CFD modeling in COMSOL Multiphysics to simulate the decomposition reaction over time in the packed bed reactor. Results showed that increasing the reaction time from 0 to 1000 seconds increased the production of hydrogen from 0 to 42 mol/dm3 and carbon from 0 to 21 mol/dm3, while decreasing methane concentration from 50 to 29 mol/dm3, indicating that decomposition was occurring. Spatial profiles of velocity, concentration, pressure and permeability within the reactor were also determined and discussed.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Density functional theory calculations were performed to investigate the structural, electronic, and CO2 adsorption properties of 55-atom bimetallic CuNi nanoparticles. The calculations revealed that decorated Cu12Ni43 and core-shell Cu42Ni13 configurations were more energetically favorable than the monometallic Cu55 and Ni55 nanoparticles. CO2 was found to chemisorb on Ni55, Cu13Ni42, Cu12Ni43, and Cu43Ni12 by undergoing a transition from linear to bent geometry and elongating the C=O bonds, while it only physisorbed on Cu55 and Cu42Ni13. The presence of surface Ni atoms played a key role in strongly adsorbing and activating CO
A simple simulation model for oxidative coupling of methaneAlexander Decker
This document describes a study that developed a mathematical model to simulate the oxidative coupling of methane over a La0.6Sr0.4NiO3 perovskite catalyst. The catalyst was prepared using a reverse microemulsion method and characterized using various techniques. Rate equations were developed based on previous studies of similar catalysts. The model can predict that at temperatures of 925°C or higher, with a methane partial pressure of 0.3 and oxygen partial pressure of 0.1, the catalyst will reach around 10% methane conversion and 50% selectivity to C2+ hydrocarbons.
This study examined how pH and redox potential (Eh) influence the leaching of mercury from mining waste materials. Laboratory experiments were conducted by varying the pH from 2 to 12 and Eh under different gas purging conditions. Results showed that mercury concentration in leachates increased with rising pH until pH 10.65, above which it sharply decreased. The presence of iron significantly reduced mercury concentrations by 1/10th to 1/100th. Varying the Eh had little effect on mercury leaching, except when hydrogen peroxide was added to increase Eh, which sharply increased mercury levels. Alkaline and reduced conditions enhanced mercury solubility the most.
Dr. Salah El Mofty - Use of Electrophoresis Technique to Study Removal of Tox...Hudhaib Al-Allatti
The document discusses using clay to remove toxic metal ions from wastewater via adsorption. Experiments show that heavy metals like lead, nickel, cobalt, and cadmium can be significantly adsorbed and removed from aqueous solutions by clay. Kinetic modeling indicates adsorption follows first-order kinetics and reaches equilibrium within 30 seconds. The adsorption capacity increases with initial metal ion concentration and pH. Overall, the experiments demonstrate that clay is effective at removing toxic metals from wastewater through adsorption.
Magnetic Fe3O4@MgAl–LDH composite grafted with cobalt phthalocyanine as an ef...Pawan Kumar
Magnetically separable layered double hydroxide MgAl–LDH@Fe3O4 composite supported cobalt
phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding
disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of
mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external
magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe3O4
support prevents the leaching of the catalyst and improves its activity and stability
This document provides an overview of catalysis and catalytic principles. It defines catalysis as the science of catalysts and catalytic processes, which plays an important role in industries like petrochemicals. A catalyst enhances the rate and selectivity of a chemical reaction while being regenerated in the process. Key points discussed include:
- Catalysts are composed of an active phase (e.g. metal), support, and optional promoters. Common supports include metal oxides like alumina.
- Reaction rate depends on temperature, pressure, concentration, and contact time according to rate laws. Temperature particularly impacts reaction rates through its exponential effect in the Arrhenius equation.
- Mass transfer and internal diffusion limitations can
This document describes a computational fluid dynamics (CFD) study of methane decomposition into hydrogen and solid carbon in a packed bed fluid catalytic cracking (FCC) reactor. The study used CFD modeling in COMSOL Multiphysics to simulate the decomposition reaction over time in the packed bed reactor. Results showed that increasing the reaction time from 0 to 1000 seconds increased the production of hydrogen from 0 to 42 mol/dm3 and carbon from 0 to 21 mol/dm3, while decreasing methane concentration from 50 to 29 mol/dm3, indicating that decomposition was occurring. Spatial profiles of velocity, concentration, pressure and permeability within the reactor were also determined and discussed.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Density functional theory calculations were performed to investigate the structural, electronic, and CO2 adsorption properties of 55-atom bimetallic CuNi nanoparticles. The calculations revealed that decorated Cu12Ni43 and core-shell Cu42Ni13 configurations were more energetically favorable than the monometallic Cu55 and Ni55 nanoparticles. CO2 was found to chemisorb on Ni55, Cu13Ni42, Cu12Ni43, and Cu43Ni12 by undergoing a transition from linear to bent geometry and elongating the C=O bonds, while it only physisorbed on Cu55 and Cu42Ni13. The presence of surface Ni atoms played a key role in strongly adsorbing and activating CO
A simple simulation model for oxidative coupling of methaneAlexander Decker
This document describes a study that developed a mathematical model to simulate the oxidative coupling of methane over a La0.6Sr0.4NiO3 perovskite catalyst. The catalyst was prepared using a reverse microemulsion method and characterized using various techniques. Rate equations were developed based on previous studies of similar catalysts. The model can predict that at temperatures of 925°C or higher, with a methane partial pressure of 0.3 and oxygen partial pressure of 0.1, the catalyst will reach around 10% methane conversion and 50% selectivity to C2+ hydrocarbons.
This study examined how pH and redox potential (Eh) influence the leaching of mercury from mining waste materials. Laboratory experiments were conducted by varying the pH from 2 to 12 and Eh under different gas purging conditions. Results showed that mercury concentration in leachates increased with rising pH until pH 10.65, above which it sharply decreased. The presence of iron significantly reduced mercury concentrations by 1/10th to 1/100th. Varying the Eh had little effect on mercury leaching, except when hydrogen peroxide was added to increase Eh, which sharply increased mercury levels. Alkaline and reduced conditions enhanced mercury solubility the most.
Dr. Salah El Mofty - Use of Electrophoresis Technique to Study Removal of Tox...Hudhaib Al-Allatti
The document discusses using clay to remove toxic metal ions from wastewater via adsorption. Experiments show that heavy metals like lead, nickel, cobalt, and cadmium can be significantly adsorbed and removed from aqueous solutions by clay. Kinetic modeling indicates adsorption follows first-order kinetics and reaches equilibrium within 30 seconds. The adsorption capacity increases with initial metal ion concentration and pH. Overall, the experiments demonstrate that clay is effective at removing toxic metals from wastewater through adsorption.
Magnetic Fe3O4@MgAl–LDH composite grafted with cobalt phthalocyanine as an ef...Pawan Kumar
Magnetically separable layered double hydroxide MgAl–LDH@Fe3O4 composite supported cobalt
phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding
disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of
mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external
magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe3O4
support prevents the leaching of the catalyst and improves its activity and stability
This document provides an overview of catalysis and catalytic principles. It defines catalysis as the science of catalysts and catalytic processes, which plays an important role in industries like petrochemicals. A catalyst enhances the rate and selectivity of a chemical reaction while being regenerated in the process. Key points discussed include:
- Catalysts are composed of an active phase (e.g. metal), support, and optional promoters. Common supports include metal oxides like alumina.
- Reaction rate depends on temperature, pressure, concentration, and contact time according to rate laws. Temperature particularly impacts reaction rates through its exponential effect in the Arrhenius equation.
- Mass transfer and internal diffusion limitations can
Balucan and Steel_2015_A regenerable precipitant-solvent system for CO2 mitig...Reydick D Balucan
This document describes a new process for CO2 mitigation and metals recovery using a regenerable solvent-precipitant system. The system uses a tertiary amine and acid that can undergo a pH swing via a change in temperature. Specifically, various tertiary amines and acids were tested to identify a combination that can adjust the pH between 10 and 2, which is suitable for metal hydroxide precipitation and metal leaching from magnesium solids. The researchers found that a triethylamine-sulfuric acid-water system could achieve a pH swing between 10.5 and 1.9 with temperature changes, meeting the criteria. This combination uses triethylamine to alkalize the solution to pH > 10.5 and uses sulfur
This document discusses gas absorption accompanied by a fast pseudo-first order photochemical reaction. It presents two cases - where the liquid reactant or the dissolved gas is activated by photons. In both cases, the specific absorption rate of the gas can be enhanced compared to no activation. Equations are derived to describe the concentration profiles and absorption rates for each case. Additional experimental data is needed to quantify the actual enhancement possible from photochemical activation in these situations.
Biomass is considered as a potential source of energy production.Gasification can be employed to convert
dilute biomass energy source in to gaseous products holding concentrated form of energy. A steady state model for fluidized
bed biomass gasifier is developed based on reaction kinetics and hydrodynamic aspects of fluidization. The presence of
sorbent for absorption of carbon dioxide from the product gas is also incorporated in the model.The developed model
predicts the variation of syngas composition, temperature, pressure and velocity along the height of gasifier. Experiments
were carried out in a lab scale fluidized bed biomass gasifier and the results were used to validate the model.An increase of
50.35% in H2 mole fraction and a decrease of 50.88 % in CO2 mole fraction were observed when CaO was used as the
sorbent.
This document summarizes a study on the adsorption of a Schiff base ligand onto granulated initiated calcined Iraqi montmorillonite clay via columnar method. The ligand was synthesized from the condensation reaction of hydrazine hydrate and 4-hydroxy-3-methoxybenzaldehyde. Adsorption experiments were conducted in columns packed with the clay at different pH levels, ligand concentrations, and contact times. The equilibrium adsorption data fit the Langmuir, Freundlich and Temkin isotherm models. The maximum adsorption capacity was found to be 5.7347 mg ligand per 1g clay. The highest removal rate of 75.7% occurred at pH 7. Kinetic data followed pseudo
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
This document describes a study investigating V and Mn incorporated mesoporous molecular sieves for the vapor phase oxidation of o-xylene. Mesoporous monometallic V-MCM-41, Mn-MCM-41, and bimetallic V-Mn-MCM-41 molecular sieves were synthesized and characterized. Their activity was measured for the gas phase oxidation of o-xylene to phthalic anhydride. Among the catalysts, V-MCM-41 with Si/V = 50 exhibited the highest activity and selectivity towards producing phthalic anhydride under the experimental conditions. The physico-chemical properties of the catalysts, including metal content, surface area,
The document summarizes a study on using palladium supported on hydrotalcite as a heterogeneous catalyst for the Suzuki cross-coupling reaction. Various palladium salts were tested as catalysts with different bases and temperatures. PdCl2 supported on hydrotalcite with potassium carbonate as the base provided the best results, with conversions comparable to homogeneous catalysts at temperatures above 90°C. The catalyst was characterized and found to have a palladium content of 1% without changing the structure of the hydrotalcite support. It was an effective catalyst for the reaction, with higher temperatures, bromobenzene, and chlorobenzene providing better conversions than other conditions tested.
Dynamic modeling and simulation of catalyticJhonatan Soto
This document summarizes a study on dynamic modeling and simulation of catalytic naphtha reforming. The dynamic model developed includes reaction kinetics, heat exchanger models, and furnace models. Kinetic modeling of the fixed bed reactors connected in series forms the core of the simulation. Reaction rates are represented using Hougen-Watson Langmuir-Hinshelwood expressions. Simulation results using MATLAB show fair agreement with plant data. The model can capture major dynamics in the reforming process system.
A review on recent progress in nitrogen doped graphene synthesis, characteriz...Science Padayatchi
1) Nitrogen doping is an effective way to modify the properties of graphene. There are three common types of nitrogen dopants: pyridinic N, pyrrolic N, and graphitic N.
2) Many methods have been used to synthesize nitrogen-doped graphene (N-graphene), including CVD, segregation growth, solvothermal synthesis, and arc discharge. Post-treatment methods include thermal treatment, plasma treatment, and treatment with N2H4.
3) The nitrogen content and dopant configuration in N-graphene can be controlled by parameters like precursor composition, catalyst material, and growth temperature. N-graphene has potential applications in areas like electrocatalysis
Catalysts accelerate chemical reactions without being consumed. There are two types of catalysts: homogeneous, where the catalyst is in the same phase as the reactants, and heterogeneous, where the catalyst is in a different phase. In heterogeneous catalysis, the catalyst is typically a solid and the reactants are gases or liquids. The catalyst provides alternative reaction pathways with lower activation energies. Enzymes are biological catalysts that work by binding reactants in cavities on their surfaces, forming activated complexes that decompose into products.
This document summarizes research on using activated Strychnos Nux-Vomica L Nano Carbon to remove Chromium (VI) ions from aqueous solution. Batch adsorption experiments were conducted to determine the effect of parameters such as contact time, initial metal concentration, adsorbent dose, pH, interfering ions, and temperature on the adsorption process. The results showed that adsorption capacity increased with temperature, reached equilibrium within 40 minutes, and was most effective at low pH between 2-7. Kinetic and thermodynamic models indicated the adsorption was physical and endothermic in nature. Overall, the study demonstrated activated Strychnos Nux-Vomica L Nano Carbon to be an effective ad
Oxidacion de etano a etileno y acido acetico con catalizadores MoVCarlos Timaná
This document discusses kinetics and mechanisms of partial oxidation of ethane to ethylene and acetic acid over molybdenum-vanadium (MoV) type catalysts. It provides background on previous studies that have suggested multi-phase catalysts are needed and that there are two catalytic sites, one for ethane oxidation and another for ethylene oxidation to acetic acid. The document then presents results of a new kinetics study investigating the effects of adding water to the feed on product formation. A reaction mechanism is proposed incorporating water participation through surface OH groups. A kinetic model is developed based on this new mechanism that satisfactorily predicts experimental results.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...suresh899
Carbon Supported PtRu nanocatalysts have been prepared by simple impregnation reduction method in which Pt and Ru precursors are reduced by ethanol under reflux conditions for different reaction times. The prepared nanocatalysts were characterized by means of XRD, EDAX, ICP-AAS, FESEM and TEM. XRD analyses showed that all nanocatalysts exhibited f.c.c crystal structure, the structure characteristic for pure Pt, except for that reduced at prolonged reaction time of 4h which showed the presence of characteristic peak for Ru metal. The lattice constant calculations indicate that all catalysts are present in unalloyed phase and the average particle size as determined by TEM was in the range of 3.7 nm. The electrocatalytic activities and stability for the prepared nanocatalysts methanol electro-oxidation reaction (MOR) were studied by cyclic voltammetry. The catalysts prepared at 2h reduction time showed higher electrocatalytic activity in terms of mass specific activity and good stability over potential sweep for 100 cycles for methanol electro-oxidation. The results showed that the prepared nanocatalysts are considered as promising electrode catalyst (anode catalyst) for electro-oxidation of methanol in direct methanol fuel cells.
Using Data-Mining Technique for Census Analysis to Give Geo-Spatial Distribut...IOSR Journals
This document discusses using data mining techniques to analyze census data and provide geographic distributions of populations in Nigeria. It specifically uses a decision tree algorithm to predict attributes of populations like number of males/females, employment status, etc. from census databases. It then integrates these predictions with a geographic information system to display the geo-spatial distributions on maps. The results showed this approach was able to successfully extract predictive attributes from census data and provide geographic distributions to help inform business and government decisions. It recommends future work address overfitting issues and better handling of continuous attributes.
Linux-Based Data Acquisition and Processing On Palmtop ComputerIOSR Journals
This document describes the development of a data acquisition and processing system using a palmtop computer running Linux. The system uses a PCMCIA data acquisition card and free Linux drivers and libraries. A demo application was created that can sample 1024 signals from a microphone at 100 ksamples/s and compute the fast Fourier transform of the signal up to 6 times per second. The document outlines the hardware and software implementation including developing the C code on a desktop, cross compiling it for the palmtop, and downloading and testing the executable on the palmtop computer. It provides details on using COMEDI libraries for data acquisition and TCL/Tk for the graphical user interface.
On The Automated Classification of Web Pages Using Artificial Neural NetworkIOSR Journals
This document discusses using artificial neural networks (ANN) for automated classification of web pages. It proposes a novel approach that uses HTML information from web pages, such as meta-tags and titles, rather than just textual content. Existing methods of web page classification are discussed, including using support vector machines, naive Bayes trees, and decision trees. The document also provides background on types of web page classification problems and compares different machine learning algorithms that have been used for classification, such as naive Bayes models and decision trees. It then introduces the proposed approach of using ANN for multi-class web page classification into predefined categories based on HTML element information.
This document summarizes a research paper that proposes new schemes called Power Spectral Density (PSD) and Spectral Flatness Measure (SFM) to detect camouflaging worms (C-worms). C-worms are a new type of worm that can hide their traffic patterns to avoid detection by existing anti-worm software. The proposed schemes aim to differentiate C-worm traffic from normal background traffic and normal worm traffic in the frequency domain, since their traffic patterns cannot be differentiated in the time domain. The results of applying PSD and SFM showed they were effective in detecting C-worms while existing detection systems could not distinguish C-worm and normal worm traffic.
Advances in Automatic Speech Recognition: From Audio-Only To Audio-Visual Sp...IOSR Journals
This document discusses advances in automatic speech recognition from audio-only to audio-visual speech recognition. It begins by providing background on early work in speech recognition and limitations of audio-only systems. It then describes the key components of audio-visual speech recognition including the audio component, visual component involving face/feature extraction and image processing, and audio-visual integration. Applications of audio-only systems like Siri and voice search are mentioned. The performance benefits of incorporating visual information to enhance noise robustness are discussed.
A Protocol to Detect and Kill Orphan Processes in Distributed Computer SystemsIOSR Journals
This document presents a protocol to detect and kill orphan processes in distributed computer systems. The protocol uses a monitor process to log all remote procedure calls (RPCs) to a global log. It sends a token to client processes that made RPCs to determine their status. If a client process is not active, the monitor sends a kill message to servers to terminate orphan processes resulting from that client's RPCs. This allows orphans to be detected and killed immediately at birth, improving on previous approaches that waited until crashed processes rebooted. The protocol handles nested RPCs and maintains data consistency by eliminating unwanted orphan computations.
Reduce the False Positive and False Negative from Real Traffic with Intrusion...IOSR Journals
This document discusses reducing false positives and false negatives in intrusion detection for zigbee wireless networks. It proposes a new approach called service-oriented traffic classification (SOTC) that uses information about previously discovered network services to classify traffic flows. The key advantages of SOTC are robustness, accuracy, and low computational requirements compared to traditional port-based and payload-based classification methods. The document provides background on related work, describes how SOTC works, and discusses some implementation considerations to make it effective in practice.
1) The document analyzes coronary heart events using weighted association rule mining on data from 1500 coronary heart disease subjects between 2003-2006 and 2009.
2) It identifies risk factors before and after heart events, generates rules to predict 56 outcomes related to coronary heart disease events, and validates 236 rules with experts.
3) The rules can be used to detect adverse drug events in past hospitalizations and prevent events during medication processes using clinical decision support systems.
Finger Print Image Compression for Extracting Texture Features and Reconstru...IOSR Journals
The document summarizes a method for fingerprint image compression that involves decomposing the image into two components - ridges (primary component) and textures/features (secondary component). The ridges are extracted and encoded using arithmetic coding combined with vector quantization, achieving a higher compression ratio than FBI standards. The decoding process reconstructs a hybrid surface based on the encoded ridges. The method allows for extracting minutiae directly from the compressed image without needing decompression, and provides both compression and the ability to reconstruct the original image. Experimental results show the compression ratio is better than FBI specified methods.
Balucan and Steel_2015_A regenerable precipitant-solvent system for CO2 mitig...Reydick D Balucan
This document describes a new process for CO2 mitigation and metals recovery using a regenerable solvent-precipitant system. The system uses a tertiary amine and acid that can undergo a pH swing via a change in temperature. Specifically, various tertiary amines and acids were tested to identify a combination that can adjust the pH between 10 and 2, which is suitable for metal hydroxide precipitation and metal leaching from magnesium solids. The researchers found that a triethylamine-sulfuric acid-water system could achieve a pH swing between 10.5 and 1.9 with temperature changes, meeting the criteria. This combination uses triethylamine to alkalize the solution to pH > 10.5 and uses sulfur
This document discusses gas absorption accompanied by a fast pseudo-first order photochemical reaction. It presents two cases - where the liquid reactant or the dissolved gas is activated by photons. In both cases, the specific absorption rate of the gas can be enhanced compared to no activation. Equations are derived to describe the concentration profiles and absorption rates for each case. Additional experimental data is needed to quantify the actual enhancement possible from photochemical activation in these situations.
Biomass is considered as a potential source of energy production.Gasification can be employed to convert
dilute biomass energy source in to gaseous products holding concentrated form of energy. A steady state model for fluidized
bed biomass gasifier is developed based on reaction kinetics and hydrodynamic aspects of fluidization. The presence of
sorbent for absorption of carbon dioxide from the product gas is also incorporated in the model.The developed model
predicts the variation of syngas composition, temperature, pressure and velocity along the height of gasifier. Experiments
were carried out in a lab scale fluidized bed biomass gasifier and the results were used to validate the model.An increase of
50.35% in H2 mole fraction and a decrease of 50.88 % in CO2 mole fraction were observed when CaO was used as the
sorbent.
This document summarizes a study on the adsorption of a Schiff base ligand onto granulated initiated calcined Iraqi montmorillonite clay via columnar method. The ligand was synthesized from the condensation reaction of hydrazine hydrate and 4-hydroxy-3-methoxybenzaldehyde. Adsorption experiments were conducted in columns packed with the clay at different pH levels, ligand concentrations, and contact times. The equilibrium adsorption data fit the Langmuir, Freundlich and Temkin isotherm models. The maximum adsorption capacity was found to be 5.7347 mg ligand per 1g clay. The highest removal rate of 75.7% occurred at pH 7. Kinetic data followed pseudo
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
This document describes a study investigating V and Mn incorporated mesoporous molecular sieves for the vapor phase oxidation of o-xylene. Mesoporous monometallic V-MCM-41, Mn-MCM-41, and bimetallic V-Mn-MCM-41 molecular sieves were synthesized and characterized. Their activity was measured for the gas phase oxidation of o-xylene to phthalic anhydride. Among the catalysts, V-MCM-41 with Si/V = 50 exhibited the highest activity and selectivity towards producing phthalic anhydride under the experimental conditions. The physico-chemical properties of the catalysts, including metal content, surface area,
The document summarizes a study on using palladium supported on hydrotalcite as a heterogeneous catalyst for the Suzuki cross-coupling reaction. Various palladium salts were tested as catalysts with different bases and temperatures. PdCl2 supported on hydrotalcite with potassium carbonate as the base provided the best results, with conversions comparable to homogeneous catalysts at temperatures above 90°C. The catalyst was characterized and found to have a palladium content of 1% without changing the structure of the hydrotalcite support. It was an effective catalyst for the reaction, with higher temperatures, bromobenzene, and chlorobenzene providing better conversions than other conditions tested.
Dynamic modeling and simulation of catalyticJhonatan Soto
This document summarizes a study on dynamic modeling and simulation of catalytic naphtha reforming. The dynamic model developed includes reaction kinetics, heat exchanger models, and furnace models. Kinetic modeling of the fixed bed reactors connected in series forms the core of the simulation. Reaction rates are represented using Hougen-Watson Langmuir-Hinshelwood expressions. Simulation results using MATLAB show fair agreement with plant data. The model can capture major dynamics in the reforming process system.
A review on recent progress in nitrogen doped graphene synthesis, characteriz...Science Padayatchi
1) Nitrogen doping is an effective way to modify the properties of graphene. There are three common types of nitrogen dopants: pyridinic N, pyrrolic N, and graphitic N.
2) Many methods have been used to synthesize nitrogen-doped graphene (N-graphene), including CVD, segregation growth, solvothermal synthesis, and arc discharge. Post-treatment methods include thermal treatment, plasma treatment, and treatment with N2H4.
3) The nitrogen content and dopant configuration in N-graphene can be controlled by parameters like precursor composition, catalyst material, and growth temperature. N-graphene has potential applications in areas like electrocatalysis
Catalysts accelerate chemical reactions without being consumed. There are two types of catalysts: homogeneous, where the catalyst is in the same phase as the reactants, and heterogeneous, where the catalyst is in a different phase. In heterogeneous catalysis, the catalyst is typically a solid and the reactants are gases or liquids. The catalyst provides alternative reaction pathways with lower activation energies. Enzymes are biological catalysts that work by binding reactants in cavities on their surfaces, forming activated complexes that decompose into products.
This document summarizes research on using activated Strychnos Nux-Vomica L Nano Carbon to remove Chromium (VI) ions from aqueous solution. Batch adsorption experiments were conducted to determine the effect of parameters such as contact time, initial metal concentration, adsorbent dose, pH, interfering ions, and temperature on the adsorption process. The results showed that adsorption capacity increased with temperature, reached equilibrium within 40 minutes, and was most effective at low pH between 2-7. Kinetic and thermodynamic models indicated the adsorption was physical and endothermic in nature. Overall, the study demonstrated activated Strychnos Nux-Vomica L Nano Carbon to be an effective ad
Oxidacion de etano a etileno y acido acetico con catalizadores MoVCarlos Timaná
This document discusses kinetics and mechanisms of partial oxidation of ethane to ethylene and acetic acid over molybdenum-vanadium (MoV) type catalysts. It provides background on previous studies that have suggested multi-phase catalysts are needed and that there are two catalytic sites, one for ethane oxidation and another for ethylene oxidation to acetic acid. The document then presents results of a new kinetics study investigating the effects of adding water to the feed on product formation. A reaction mechanism is proposed incorporating water participation through surface OH groups. A kinetic model is developed based on this new mechanism that satisfactorily predicts experimental results.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...suresh899
Carbon Supported PtRu nanocatalysts have been prepared by simple impregnation reduction method in which Pt and Ru precursors are reduced by ethanol under reflux conditions for different reaction times. The prepared nanocatalysts were characterized by means of XRD, EDAX, ICP-AAS, FESEM and TEM. XRD analyses showed that all nanocatalysts exhibited f.c.c crystal structure, the structure characteristic for pure Pt, except for that reduced at prolonged reaction time of 4h which showed the presence of characteristic peak for Ru metal. The lattice constant calculations indicate that all catalysts are present in unalloyed phase and the average particle size as determined by TEM was in the range of 3.7 nm. The electrocatalytic activities and stability for the prepared nanocatalysts methanol electro-oxidation reaction (MOR) were studied by cyclic voltammetry. The catalysts prepared at 2h reduction time showed higher electrocatalytic activity in terms of mass specific activity and good stability over potential sweep for 100 cycles for methanol electro-oxidation. The results showed that the prepared nanocatalysts are considered as promising electrode catalyst (anode catalyst) for electro-oxidation of methanol in direct methanol fuel cells.
Using Data-Mining Technique for Census Analysis to Give Geo-Spatial Distribut...IOSR Journals
This document discusses using data mining techniques to analyze census data and provide geographic distributions of populations in Nigeria. It specifically uses a decision tree algorithm to predict attributes of populations like number of males/females, employment status, etc. from census databases. It then integrates these predictions with a geographic information system to display the geo-spatial distributions on maps. The results showed this approach was able to successfully extract predictive attributes from census data and provide geographic distributions to help inform business and government decisions. It recommends future work address overfitting issues and better handling of continuous attributes.
Linux-Based Data Acquisition and Processing On Palmtop ComputerIOSR Journals
This document describes the development of a data acquisition and processing system using a palmtop computer running Linux. The system uses a PCMCIA data acquisition card and free Linux drivers and libraries. A demo application was created that can sample 1024 signals from a microphone at 100 ksamples/s and compute the fast Fourier transform of the signal up to 6 times per second. The document outlines the hardware and software implementation including developing the C code on a desktop, cross compiling it for the palmtop, and downloading and testing the executable on the palmtop computer. It provides details on using COMEDI libraries for data acquisition and TCL/Tk for the graphical user interface.
On The Automated Classification of Web Pages Using Artificial Neural NetworkIOSR Journals
This document discusses using artificial neural networks (ANN) for automated classification of web pages. It proposes a novel approach that uses HTML information from web pages, such as meta-tags and titles, rather than just textual content. Existing methods of web page classification are discussed, including using support vector machines, naive Bayes trees, and decision trees. The document also provides background on types of web page classification problems and compares different machine learning algorithms that have been used for classification, such as naive Bayes models and decision trees. It then introduces the proposed approach of using ANN for multi-class web page classification into predefined categories based on HTML element information.
This document summarizes a research paper that proposes new schemes called Power Spectral Density (PSD) and Spectral Flatness Measure (SFM) to detect camouflaging worms (C-worms). C-worms are a new type of worm that can hide their traffic patterns to avoid detection by existing anti-worm software. The proposed schemes aim to differentiate C-worm traffic from normal background traffic and normal worm traffic in the frequency domain, since their traffic patterns cannot be differentiated in the time domain. The results of applying PSD and SFM showed they were effective in detecting C-worms while existing detection systems could not distinguish C-worm and normal worm traffic.
Advances in Automatic Speech Recognition: From Audio-Only To Audio-Visual Sp...IOSR Journals
This document discusses advances in automatic speech recognition from audio-only to audio-visual speech recognition. It begins by providing background on early work in speech recognition and limitations of audio-only systems. It then describes the key components of audio-visual speech recognition including the audio component, visual component involving face/feature extraction and image processing, and audio-visual integration. Applications of audio-only systems like Siri and voice search are mentioned. The performance benefits of incorporating visual information to enhance noise robustness are discussed.
A Protocol to Detect and Kill Orphan Processes in Distributed Computer SystemsIOSR Journals
This document presents a protocol to detect and kill orphan processes in distributed computer systems. The protocol uses a monitor process to log all remote procedure calls (RPCs) to a global log. It sends a token to client processes that made RPCs to determine their status. If a client process is not active, the monitor sends a kill message to servers to terminate orphan processes resulting from that client's RPCs. This allows orphans to be detected and killed immediately at birth, improving on previous approaches that waited until crashed processes rebooted. The protocol handles nested RPCs and maintains data consistency by eliminating unwanted orphan computations.
Reduce the False Positive and False Negative from Real Traffic with Intrusion...IOSR Journals
This document discusses reducing false positives and false negatives in intrusion detection for zigbee wireless networks. It proposes a new approach called service-oriented traffic classification (SOTC) that uses information about previously discovered network services to classify traffic flows. The key advantages of SOTC are robustness, accuracy, and low computational requirements compared to traditional port-based and payload-based classification methods. The document provides background on related work, describes how SOTC works, and discusses some implementation considerations to make it effective in practice.
1) The document analyzes coronary heart events using weighted association rule mining on data from 1500 coronary heart disease subjects between 2003-2006 and 2009.
2) It identifies risk factors before and after heart events, generates rules to predict 56 outcomes related to coronary heart disease events, and validates 236 rules with experts.
3) The rules can be used to detect adverse drug events in past hospitalizations and prevent events during medication processes using clinical decision support systems.
Finger Print Image Compression for Extracting Texture Features and Reconstru...IOSR Journals
The document summarizes a method for fingerprint image compression that involves decomposing the image into two components - ridges (primary component) and textures/features (secondary component). The ridges are extracted and encoded using arithmetic coding combined with vector quantization, achieving a higher compression ratio than FBI standards. The decoding process reconstructs a hybrid surface based on the encoded ridges. The method allows for extracting minutiae directly from the compressed image without needing decompression, and provides both compression and the ability to reconstruct the original image. Experimental results show the compression ratio is better than FBI specified methods.
Design and Implementation of Single Leg Reduce Switch Count Dual Output Inver...IOSR Journals
This document describes a proposed three-switch single-leg inverter topology that can independently supply two AC loads using reduced semiconductor switches compared to conventional six-switch topologies. The three-switch inverter uses three semiconductor switches and three parallel capacitors to generate independent outputs of varying frequency and amplitude. Simulation and experimental results show that the three-switch inverter can successfully drive two AC loads independently while reducing components, cost, size and weight compared to traditional designs.
Performance Comparison of K-means Codebook Optimization using different Clust...IOSR Journals
The document compares the performance of codebook optimization using different clustering techniques with the K-means algorithm. It first describes vector quantization as a lossy image compression technique that relies on an optimal codebook. It then discusses using K-means clustering to iteratively optimize the codebook by minimizing the mean square error. The document generates codebooks using LBG, KPE, KFCG, and random selection, and applies K-means optimization to each. It finds that KFCG results in the lowest mean square error, indicating it produces a codebook closest to the optimal solution when used with K-means optimization.
The document discusses using DNA sequences to encrypt data uniquely for each individual. It proposes assigning each of the four DNA components (adenine, thymine, guanine, cytosine) a fixed algorithm. The encryption sequence would then be based on the individual's unique DNA component sequence. This could reduce complex algorithms and keys needed while making the encrypted data difficult to decrypt even if keys are identified, since the plain text could not be retrieved without knowing the exact DNA sequence. The methodology and algorithms considered for this approach are also discussed.
Universal Artificial Intelligence for Intelligent Agents: An Approach to Supe...IOSR Journals
This document proposes a methodology to develop intelligent agents with universal artificial intelligence (UAI) that can operate effectively in new environments. The methodology uses a neuro-fuzzy system combined with a hidden Markov model (HMM) to provide agents with learning capabilities and the ability to make decisions in unknown environments. The neuro-fuzzy system would extract fuzzy rules and membership functions from data to guide an agent. The HMM would generate sequences of sensed states to model dynamic environments. This approach aims to create "super intelligent agents" that can perform human-level tasks in any computable environment without reprogramming. A literature review found that neuro-fuzzy and HMM methods have been successfully used for mobile robot obstacle avoidance and human motion recognition.
This document outlines the content of a biostatistics course. It introduces statistics, defining it as the collection, organization, analysis and interpretation of data to draw conclusions. It discusses descriptive and inferential statistics. It also covers topics like data classification, levels of measurement, sampling techniques and methods of data collection that will be taught in the course's first four chapters. These chapters will address central tendency, variation, frequency distributions, and range.
Implementation of Matching Tree Technique for Online Record LinkageIOSR Journals
This document discusses the implementation of a matching tree technique for online record linkage. It begins with an introduction to the record linkage problem and issues that arise when linking records across distributed, heterogeneous databases. It then reviews related work on record linkage techniques. The objective is to develop a matching tree approach to reduce the communication overhead of online record linkage while providing accurate matching decisions. The document outlines the proposed technique and discusses how it was implemented and evaluated using real and synthetic databases.
Performance on Image Segmentation Resulting In Canny and MoGIOSR Journals
The document discusses image segmentation techniques using the Canny edge detector and Mixture of Gaussians (MoG) classifier. It begins with an abstract discussing how images are analyzed using features like edges, color, texture, and shape. It then discusses the Canny edge detector, noting it was developed to detect a wide range of edges in a multi-stage algorithm. The document focuses on improving image classification accuracy by combining natural image statistics and scene semantics features in a MoG classifier with an integrated feature weighting model.
Use of Storage Water in a Hydroelectric SystemIOSR Journals
This document discusses the use of storage water in hydroelectric systems. It begins by discussing how hydroelectric systems work and the importance of water storage. It then reviews several past studies that have analyzed optimal water storage and use in hydroelectric systems. These studies used different assumptions and approaches, such as using decision support systems and dynamic programming. The document proposes using an existing decision support system to optimize water use during low flow periods. It describes the components and benefits of comprehensive decision support systems for hydroelectric operations and planning. Finally, it concludes that decision support systems can optimize water storage and use in hydroelectric systems based on updated forecasts and probabilistic modeling.
No Wonder It's So Hard To Make Money Online!believe52
The document discusses the problem of information overload that internet marketers face. They are constantly bombarded by new offers and programs claiming to help make money online. This causes internet marketers to get distracted and switch between different projects without fully developing any of them. The document provides five tips to help internet marketers fix this issue: 1) only check emails at set times, 2) commit to developing one project at a time without deviating, 3) make to-do lists, 4) set aside dedicated productive time each day, and 5) only work on one money-making project at a time until it is successful or proven not to work. The key is maintaining focus on one idea or program until completion.
Channel Fading Detection in Manets with Hand off StrategyIOSR Journals
This document proposes a novel Channel-Aware AOMDV (CA-AOMDV) routing protocol for mobile ad hoc networks that uses channel state information to select stable links and implement a preemptive handoff strategy. It uses the average nonfading duration of links as a routing metric to choose paths with stable links. When link quality starts to fade, it performs a handoff to a better quality link to avoid disconnections. It allows paths to be reused when available again rather than discarded. Simulation and theoretical results show CA-AOMDV has improved network performance over AOMDV in terms of reduced routing overhead and packet drops.
Computational Fluid Dynamic Study On The Decomposition Of Methane Gas Into Hy...IOSR Journals
This document describes a computational fluid dynamics (CFD) study of methane decomposition into hydrogen and solid carbon in a packed bed fluid catalytic cracking (FCC) reactor. The study used CFD modeling in COMSOL Multiphysics to simulate the reaction over time and space in the reactor. Results showed that increasing reaction time from 0 to 1000 seconds increased hydrogen production from 0 to 42 mol/dm3 and carbon production from 0 to 21 mol/dm3, while decreasing methane concentration from 50 to 29 mol/dm3, indicating decomposition was occurring. Carbon deposition on the catalyst was faster initially but slowed above 500 seconds. When catalyst deactivation was included, less hydrogen and carbon were produced compared to without deactivation, showing it
This document summarizes a study that used computational fluid dynamics (CFD) modeling to simulate the operation of a catalytic converter used to reduce nitrogen oxide (NOx) emissions from automobile exhaust. Specifically, it used the Comsol Multiphysics software to model a catalytic converter that injects ammonia to selectively reduce NOx to nitrogen and water through heterogeneous surface reactions on the catalyst. The model considers fluid flow, mass transfer, heat transfer and chemical reactions in both the channels and walls of the monolith structure. The study aims to optimize the ammonia injection level and investigate other operating parameters to improve the catalytic converter's NOx reduction efficiency.
Enhanced fluidized bed methanation over a Ni Al2O3 catalyst for production of...Pengcheng Li
This document summarizes a study that investigated the fluidization behavior and CO methanation performance of a Ni/Al2O3 catalyst in a fluidized bed reactor for producing synthetic natural gas. The researchers found that the pure Ni/Al2O3 catalyst failed to properly fluidize on its own due to particle sizes between 10 and 100 μm, but fluidization was improved by adding larger Al2O3 particles. Methanation performance in the fluidized bed reactor increased substantially with the Al2O3 addition. Temperature was found to control the methanation reaction mechanism, with surface reactions dominating at lower temperatures and external diffusion controlling at higher temperatures. Stability tests showed the fluidized bed reactor had higher CO conversion, methane selectivity
This document summarizes a study that models selective catalytic reduction (SCR) of nitric oxide by ammonia in a fixed-bed reactor using COMSOL Multiphysics software. The model considers a two-dimensional cylindrical reactor geometry and couples equations for mass and momentum transport along with the Brinkman equation to account for porosity. Kinetic data from literature was used and conversions were calculated from concentration results. Model results were within 5% of experimental data, validating the model. A parametric study examined the effects of reactant concentrations, temperature, water content, and porosity on conversion percentages.
In order to study the WGS on an industrial scale at a low pressure, the modeling andsimulation of a WGS reactor operating at a pressure close to Patm and processing an industrial charge in the presence of a high temperature shift catalyst (Fe2O3/Cr2O3) were performed. The Profiles of the carbon monoxide conversion, temperature and pressure along the reactor were obtained. The effect of several operating parameters (inlet temperature, H2O/CO ratio) on the conversion of carbon monoxide along the reactor has been determined. The estimated catalytic mass to convert 60.5% of the carbon monoxide contained in the inlet is 170.76 t. The pressure drops in the reactor are not negligible and the maximum temperaturereached is without any harmful effect on the catalyst. The choice of an optimal inlet temperature and a high H2O/CO ratio improves the conversion of carbon monoxide.
This document summarizes a study on the kinetics of methanol synthesis from carbon dioxide hydrogenation over copper-zinc oxide catalysts. Experiments were conducted in a fixed bed reactor between 200-230°C, 50-80 bar, and gas hourly space velocities of 7,800-23,400 h-1 using feeds with H2:CO2 ratios of 2-6 without CO. Kinetic parameters from a previous study were optimized to model the experimental data using a Langmuir–Hinshelwood–Hougen–Watson mechanism. The influences of catalyst support (alumina vs zirconia) and operating conditions on kinetics were examined. The goal was to determine optimized parameters to reliably scale-up the
This document summarizes a study examining the use of alumina-supported nickel catalysts promoted with zirconia, ceria, and magnesia for dry reforming of methane. Dry reforming of methane is presented as an environmentally friendly process for producing synthesis gas. Nickel catalysts are commonly used but are prone to deactivation from carbon deposition; the study investigated how promoter oxides could improve catalyst activity and stability. Catalysts with 10% nickel loading promoted with 5% zirconia showed the highest methane conversion, while 5% ceria promotion led to the best stability based on characterization of fresh and used catalysts.
This document describes a model developed to predict the optimal reaction temperature of an industrial fluid catalytic cracking (FCC) unit riser. A pseudo-homogeneous two-dimensional model was developed using a five-lump reaction scheme. Mass transfer resistance was incorporated to improve accuracy over previous one-dimensional plug flow models. Finite difference methods were used to discretize the governing equations which were then solved using MATLAB. Simulation results identified three temperature regimes for catalyst coking. An optimum temperature range of 786K-788K and catalyst-to-oil ratio range of 4.60-4.71 were predicted to minimize coke on catalyst without reducing gasoline yield.
This document describes a model developed to predict the optimal reaction temperature of an industrial fluid catalytic cracking (FCC) unit riser. A pseudo-homogeneous two-dimensional model was developed using a five-lump reaction scheme. Mass transfer resistance was incorporated to improve accuracy over previous one-dimensional plug flow models. Finite difference methods were used to discretize the governing equations which were then solved using MATLAB. Simulation results identified three temperature regimes for catalyst coking. An optimum temperature range of 786K-788K and catalyst-to-oil ratio range of 4.60-4.71 were predicted to minimize coke on catalyst without reducing gasoline yield.
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
Abstract: New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency.
A simple simulation model for oxidative coupling of methaneAlexander Decker
This document describes a study that developed a mathematical model to simulate the oxidative coupling of methane over a La0.6Sr0.4NiO3 perovskite catalyst. The catalyst was prepared using a reverse microemulsion method and characterized using various techniques. Rate equations were developed based on previous studies of similar catalysts. The model can predict methane conversion and selectivity to C2+ hydrocarbons at temperatures of 925°C or higher with methane and oxygen partial pressures of 0.3 and 0.1, respectively, of around 10% conversion and 50% selectivity.
This document summarizes a study that investigated the effect of granulation on the activity and stability of a Co-Al2O3 aerogel catalyst for methane-carbon dioxide reforming in a fluidized-bed reactor. The aerogel catalyst was granulated using ethanol as a binding agent to improve its fluidization properties. Testing found that granulation significantly improved the catalytic performance of the aerogel catalyst, giving it better stability and higher methane conversion compared to the non-granulated catalyst. The improved performance was attributed to the better fluidization quality achieved through granulation.
Optimal Heat Exchanger Rating Models for Isothermal CSTR SO3 Hydration Using ...INFOGAIN PUBLICATION
This work deals with the development of design models for heat exchanger rating in catalytic sulphur trioxide hydration process at isothermal condition exploiting the Abowei and Goodhead derived continuous adsorption tower (CAST) heat generation per unit volume equations at constant temperature. Shell and Tube heat exchanger is invoked for this studies resulting to novel design equations which were stochastically examined and found to be capable of simulating the rating performance dimensions as a function of kinetic parameters. The rating performance models were further generalized to inculcate fractional conversion functionality. The novel design models were simulation to evaluate the overall heat transfer coefficient, mass flow rate of cooling fluid, tube side cross flow area and tube side film coefficient using Matlab R2007B within the operational limits of conversion degree at constant temperature. The heat exchanger is used for the removal of heat generated per reactor unit volume utilizing water as cooling fluid, enters the shell side at 25oC flowing counter currently to the tube side at exit temperature of 85oC in order to maintaining 97oC isothermal condition. The configuration of the exchanger is U–tube type and is three (3) shell and six (6) tube passes. The results of the rating dimensions showed a dependable relationship with fractional conversion at constant temperature for various reactor radius and number of tubes.
Study on Coupling Model of Methanol Steam Reforming and Simultaneous Hydrogen...IOSR Journals
1) A simplified mechanistic model was developed for coupling methanol steam reforming and hydrogen combustion in microchannels of a parallel plate reactor. The reforming reaction is endothermic and requires heat, which is provided by the exothermic hydrogen combustion reaction in an adjacent channel.
2) Kinetic expressions were used to model the reforming and combustion reactions. MATLAB simulations were performed to analyze parameters like temperature, velocity and conversion. Operative diagrams showed the temperature and velocities required for complete methanol conversion.
3) Efficiency curves were generated based on hydrogen produced versus consumed. With a molar ratio of 0.9664, the maximum efficiency was 86.8%, indicating over 80% efficiency is achievable via coupling of
Chemical Looping Combustion of Rice HuskIJERA Editor
A thermodynamic investigation of direct chemical looping combustion (CLC) of rice husk is presented in this paper. Both steam and CO2 are used for gasification within the temperature range of 500–1200˚C and different amounts of oxygen carriers. Chemical equilibrium model was considered for the CLC fuel reactor. The trends in product compositions of the fuel reactor, were determined. Rice husk gasification using 3 moles H2O and 0 moles CO2 per mole carbon (in rice husk) at 1 bar pressure and 900˚C was found to be the best operating point for hundred percent carbon conversion in the fuel reactor. Such detailed thermodynamic studies can be useful to design chemical looping combustion processes using different fuels.
Chemical Looping Combustion of Rice HuskIJERA Editor
A thermodynamic investigation of direct chemical looping combustion (CLC) of rice husk is presented in this paper. Both steam and CO2 are used for gasification within the temperature range of 500–1200˚C and different amounts of oxygen carriers. Chemical equilibrium model was considered for the CLC fuel reactor. The trends in product compositions of the fuel reactor, were determined. Rice husk gasification using 3 moles H2O and 0 moles CO2 per mole carbon (in rice husk) at 1 bar pressure and 900˚C was found to be the best operating point for hundred percent carbon conversion in the fuel reactor. Such detailed thermodynamic studies can be useful to design chemical looping combustion processes using different fuels.
SYNGAS PRODUCTION BY DRY REFORMING OF METHANE OVER CO-PRECIPITATED CATALYSTSIAEME Publication
The syngas manufacturing from the reforming of methane with carbon dioxide is tempting because of output in terms of extra pure synthesis gas and lower H2 to CO ratio than other synthesis gas production methods like either partial oxidation or steam reforming. For production of long-chain hydrocarbons though the Fischer-Tropsch synthesis, lower H2 to CO ratio is required and important, as it is a most likely feedstock. In recent decades, CO2 utilization has become more and more important in view of the emergent global warming phenomenon. On the environmental point of view, methane reforming is tantalizing due to the reduction of carbon dioxide and methane emissions as both are consider as dangerous greenhouse gases. Commercially, as cost effectively, nickel is used for methane reforming reactions due to its availability and lower cost compared to noble metals. Number of catalysts endures rigorous deactivation because of carbon deposition. Mainly carbon formation is because of methane decomposition and CO disproportionate. It is important and required to recognize essential steps of activation and conversion of CH4 and CO2 to design catalysts that minimize deactivation. Effect of promoters on activity and stability were studied in the detail. In order to develop the highly active with minimum coke formation the alkali metal oxides and ceria/zirconia/magnesia promoters were incorporated in the catalysts. The influence of ZrO2, CeO2 and MgO, in the performance of Ni-Al2O3 catalyst, prepare by co-precipitation method was studied in detailed. The XRD, FTIR, and BET and reactivity test for different promoted and unprompted catalyst was carried out.
CFD investigation of coal gasification: Effect of particle sizeIRJET Journal
This document presents a computational fluid dynamics (CFD) investigation of the effect of coal particle size on coal gasification in a fluidized bed. The CFD model uses Eulerian-Eulerian two-fluid modeling approach with kinetic theory of granular flow to simulate gas-solid flow behavior. Simulations were performed with two particle sizes - 0.00062 m and 0.001 m - at fluidization velocities ranging from 0.16 to 1 m/s. The results show that smaller particle size leads to better solid distribution, easier generation of bubbles, and faster fluidization. At high velocities, particle size has little effect other than on bed height expansion. The study provides insights into how particle size impacts hydrodynamics in fluid
1. The document describes a mathematical model developed to model esterification in a batch reactor coupled with pervaporation for producing ethyl acetate.
2. The model accounts for the reaction kinetics of esterification catalyzed by Amberlyst 15 resin and permeation rates of components through a polydimethylsiloxane membrane based on experimental data.
3. A parametric study using the model found that conversion increases with increasing temperature, molar ratios of reactants, and catalyst concentration, with optimal conditions being a temperature of around 343K, catalyst concentration of 10g, and 50% excess acetic acid relative to ethanol.
This document provides a technical review of secure banking using RSA and AES encryption methodologies. It discusses how RSA and AES are commonly used encryption standards for secure data transmission between ATMs and bank servers. The document first provides background on ATM security measures and risks of attacks. It then reviews related work analyzing encryption techniques. The document proposes using a one-time password in addition to a PIN for ATM authentication. It concludes that implementing encryption standards like RSA and AES can make transactions more secure and build trust in online banking.
This document analyzes the performance of various modulation schemes for achieving energy efficient communication over fading channels in wireless sensor networks. It finds that for long transmission distances, low-order modulations like BPSK are optimal due to their lower SNR requirements. However, as transmission distance decreases, higher-order modulations like 16-QAM and 64-QAM become more optimal since they can transmit more bits per symbol, outweighing their higher SNR needs. Simulations show lifetime extensions up to 550% are possible in short-range networks by using higher-order modulations instead of just BPSK. The optimal modulation depends on transmission distance and balancing the energy used by electronic components versus power amplifiers.
This document provides a review of mobility management techniques in vehicular ad hoc networks (VANETs). It discusses three modes of communication in VANETs: vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and hybrid vehicle (HV) communication. For each communication mode, different mobility management schemes are required due to their unique characteristics. The document also discusses mobility management challenges in VANETs and outlines some open research issues in improving mobility management for seamless communication in these dynamic networks.
This document provides a review of different techniques for segmenting brain MRI images to detect tumors. It compares the K-means and Fuzzy C-means clustering algorithms. K-means is an exclusive clustering algorithm that groups data points into distinct clusters, while Fuzzy C-means is an overlapping clustering algorithm that allows data points to belong to multiple clusters. The document finds that Fuzzy C-means requires more time for brain tumor detection compared to other methods like hierarchical clustering or K-means. It also reviews related work applying these clustering algorithms to segment brain MRI images.
1) The document simulates and compares the performance of AODV and DSDV routing protocols in a mobile ad hoc network under three conditions: when users are fixed, when users move towards the base station, and when users move away from the base station.
2) The results show that both protocols have higher packet delivery and lower packet loss when users are either fixed or moving towards the base station, since signal strength is better in those scenarios. Performance degrades when users move away from the base station due to weaker signals.
3) AODV generally has better performance than DSDV, with higher throughput and packet delivery rates observed across the different user mobility conditions.
This document describes the design and implementation of 4-bit QPSK and 256-bit QAM modulation techniques using MATLAB. It compares the two techniques based on SNR, BER, and efficiency. The key steps of implementing each technique in MATLAB are outlined, including generating random bits, modulation, adding noise, and measuring BER. Simulation results show scatter plots and eye diagrams of the modulated signals. A table compares the results, showing that 256-bit QAM provides better performance than 4-bit QPSK. The document concludes that QAM modulation is more effective for digital transmission systems.
The document proposes a hybrid technique using Anisotropic Scale Invariant Feature Transform (A-SIFT) and Robust Ensemble Support Vector Machine (RESVM) to accurately identify faces in images. A-SIFT improves upon traditional SIFT by applying anisotropic scaling to extract richer directional keypoints. Keypoints are processed with RESVM and hypothesis testing to increase accuracy above 95% by repeatedly reprocessing images until the threshold is met. The technique was tested on similar and different facial images and achieved better results than SIFT in retrieval time and reduced keypoints.
This document studies the effects of dielectric superstrate thickness on microstrip patch antenna parameters. Three types of probes-fed patch antennas (rectangular, circular, and square) were designed to operate at 2.4 GHz using Arlondiclad 880 substrate. The antennas were tested with and without an Arlondiclad 880 superstrate of varying thicknesses. It was found that adding a superstrate slightly degraded performance by lowering the resonant frequency and increasing return loss and VSWR, while decreasing bandwidth and gain. Specifically, increasing the superstrate thickness or dielectric constant resulted in greater changes to the antenna parameters.
This document describes a wireless environment monitoring system that utilizes soil energy as a sustainable power source for wireless sensors. The system uses a microbial fuel cell to generate electricity from the microbial activity in soil. Two microbial fuel cells were created using different soil types and various additives to produce different current and voltage outputs. An electronic circuit was designed on a printed circuit board with components like a microcontroller and ZigBee transceiver. Sensors for temperature and humidity were connected to the circuit to monitor the environment wirelessly. The system provides a low-cost way to power remote sensors without needing battery replacement and avoids the high costs of wiring a power source.
1) The document proposes a model for a frequency tunable inverted-F antenna that uses ferrite material.
2) The resonant frequency of the antenna can be significantly shifted from 2.41GHz to 3.15GHz, a 31% shift, by increasing the static magnetic field placed on the ferrite material.
3) Altering the permeability of the ferrite allows tuning of the antenna's resonant frequency without changing the physical dimensions, providing flexibility to operate over a wide frequency range.
This document summarizes a research paper that presents a speech enhancement method using stationary wavelet transform. The method first classifies speech into voiced, unvoiced, and silence regions based on short-time energy. It then applies different thresholding techniques to the wavelet coefficients of each region - modified hard thresholding for voiced speech, semi-soft thresholding for unvoiced speech, and setting coefficients to zero for silence. Experimental results using speech from the TIMIT database corrupted with white Gaussian noise at various SNR levels show improved performance over other popular denoising methods.
This document reviews the design of an energy-optimized wireless sensor node that encrypts data for transmission. It discusses how sensing schemes that group nodes into clusters and transmit aggregated data can reduce energy consumption compared to individual node transmissions. The proposed node design calculates the minimum transmission power needed based on received signal strength and uses a periodic sleep/wake cycle to optimize energy when not sensing or transmitting. It aims to encrypt data at both the node and network level to further optimize energy usage for wireless communication.
This document discusses group consumption modes. It analyzes factors that impact group consumption, including external environmental factors like technological developments enabling new forms of online and offline interactions, as well as internal motivational factors at both the group and individual level. The document then proposes that group consumption modes can be divided into four types based on two dimensions: vertical (group relationship intensity) and horizontal (consumption action period). These four types are instrument-oriented, information-oriented, enjoyment-oriented, and relationship-oriented consumption modes. Finally, the document notes that consumption modes are dynamic and can evolve over time.
The document summarizes a study of different microstrip patch antenna configurations with slotted ground planes. Three antenna designs were proposed and their performance evaluated through simulation: a conventional square patch, an elliptical patch, and a star-shaped patch. All antennas were mounted on an FR4 substrate. The effects of adding different slot patterns to the ground plane on resonance frequency, bandwidth, gain and efficiency were analyzed parametrically. Key findings were that reshaping the patch and adding slots increased bandwidth and shifted resonance frequency. The elliptical and star patches in particular performed better than the conventional design. Three antenna configurations were selected for fabrication and measurement based on the simulations: a conventional patch with a slot under the patch, an elliptical patch with slots
1) The document describes a study conducted to improve call drop rates in a GSM network through RF optimization.
2) Drive testing was performed before and after optimization using TEMS software to record network parameters like RxLevel, RxQuality, and events.
3) Analysis found call drops were occurring due to issues like handover failures between sectors, interference from adjacent channels, and overshooting due to antenna tilt.
4) Corrective actions taken included defining neighbors between sectors, adjusting frequencies to reduce interference, and lowering the mechanical tilt of an antenna.
5) Post-optimization drive testing showed improvements in RxLevel, RxQuality, and a reduction in dropped calls.
This document describes the design of an intelligent autonomous wheeled robot that uses RF transmission for communication. The robot has two modes - automatic mode where it can make its own decisions, and user control mode where a user can control it remotely. It is designed using a microcontroller and can perform tasks like object recognition using computer vision and color detection in MATLAB, as well as wall painting using pneumatic systems. The robot's movement is controlled by DC motors and it uses sensors like ultrasonic sensors and gas sensors to navigate autonomously. RF transmission allows communication between the robot and a remote control unit. The overall aim is to develop a low-cost robotic system for industrial applications like material handling.
This document reviews cryptography techniques to secure the Ad-hoc On-Demand Distance Vector (AODV) routing protocol in mobile ad-hoc networks. It discusses various types of attacks on AODV like impersonation, denial of service, eavesdropping, black hole attacks, wormhole attacks, and Sybil attacks. It then proposes using the RC6 cryptography algorithm to secure AODV by encrypting data packets and detecting and removing malicious nodes launching black hole attacks. Simulation results show that after applying RC6, the packet delivery ratio and throughput of AODV increase while delay decreases, improving the security and performance of the network under attack.
The document describes a proposed modification to the conventional Booth multiplier that aims to increase its speed by applying concepts from Vedic mathematics. Specifically, it utilizes the Urdhva Tiryakbhyam formula to generate all partial products concurrently rather than sequentially. The proposed 8x8 bit multiplier was coded in VHDL, simulated, and found to have a path delay 44.35% lower than a conventional Booth multiplier, demonstrating its potential for higher speed.
This document discusses image deblurring techniques. It begins by introducing image restoration and focusing on image deblurring. It then discusses challenges with image deblurring being an ill-posed problem. It reviews existing approaches to screen image deconvolution including estimating point spread functions and iteratively estimating blur kernels and sharp images. The document also discusses handling spatially variant blur and summarizes the relationship between the proposed method and previous work for different blur types. It proposes using color filters in the aperture to exploit parallax cues for segmentation and blur estimation. Finally, it proposes moving the image sensor circularly during exposure to prevent high frequency attenuation from motion blur.
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1. IOSR Journal of Applied Chemistry (IOSR-JAC)
e-ISSN: 2278-5736.Volume 4, Issue 2 (Mar. – Apr. 2013), PP 19-31
www.iosrjournals.org
www.iosrjournals.org 19 | Page
Modeling Of Carbon Deposit From Methane Gas On Zeolite Y
Catalyst Activity In A Packed Bed Reactor
Ibrahim, S., Onifade, K.R., Kovo, A.S., Abdulkadir, M. and Otaru, A.J.
1
(Ovecon Engineering and Consultancy, P.O. Box 1730, Zaria, Nigeria)
2,3,4&5
(Department of Chemical Engineering, Federal Univeristy of Technology, PMB 065, Gidan Kwanu,
Minna, Niger State, Nigeria).
ABSTRACT: The purpose of this research work is to study the effects of carbon deposit from methane gas on
Zeolite Y catalyst activity in a packed bed reactor. Compuational fluid dynamic model was carried with the aid
of chosen geometry, governing equation, properties of the fluid and time step. Result shows that increase in
time from 0 to 1000s yielded an increase in the formation of hydrogen from 0 to 42mol/dm3
, increased carbon
from 0 to 21mol/dm3
, and decreased methane concentration from 50 to 29mol/dm3
. It shows that methane
decomposition is taking place. the carbon deposition on catalyst is faster from time 0 to 400 s and above 500 s
carbon deposition is lower. This shows that the variation of catalyst activity dropped on carbon deposition. The
concentration of carbon and hydrogen formed is less when catalyst deactivation is taking place compared to
when catalyst deactivation is not taking place.
Keywords: Carbon, Deposit, Methane, Reactor and Zeaolite Y.
I. Introduction
The recent development in petroleum refining technology has brought the hydro processing reaction to a
level of economic importance matching cracking and reforming (Wilson, 1997). Carbon deposition onto the
surface of solid catalysts is commonly observed in hydrocarbon processing. Carbon deposits can affect both the
activity of catalysts as well as the flow of gas through a catalyst bed. These effects of carbon deposit vary from
one type of catalyst to another (Szepe and Levenspiel, 1971). Comsol, 2008 investigated the effect of carbon
deposit has on Ni/Al2O3 catalyst due to methane decomposition in a packed bed reactor and concluded that
carbon deposit affect Ni/Al2O3 catalyst activity gas flow through the packed bed.
Catalyst developed for fluid catalytic cracking as stated by (Gates et -al 1979) includes zeolite.
Commercial FCC catalyst consist of zeolite y and dispersed in a porous amorphous matrix comprised of clay
and are held together by binder. The zeolite y and active alumina dispersed in a porous amorphous matrix
comprised of clay catalyst are in most general use today because they have proven to be highly selective, easy to
regenerate, and resistant to poisons.
Carbon deposition onto the surface of solid catalysts is commonly observed in hydrocarbon processing.
Carbon deposits can affect both the activity of catalysts as well as the flow of gas through a catalyst bed (Sharif
et al., 2004). Catalyst loss it activity with time-on- stream that is deactivation is one of the major problems
related to the operation of heterogeneous catalysis. The deactivation process occur both chemical and physical
nature simultaneously with the main reaction were commonly divided in to four classes poisoning, coking,
fouling and loss of active element. Deactivation is inevitable but can be slowed or prevented and some of it is
consequences can be avoided (Corolla et al., 1997).
In Nigeria, the Petroleum Technology Development Fund (PTDF) setup a chair in Ahmadu Bello
University Zaria to produce indigenous catalyst (Zeolite Y) in other to promote local content. In view of this it is
necessary to investigate how carbon deposits can affect both the activity of catalysts as well as the flow of gas
through a catalyst bed.
Computational fluid dynamic (CFD) is a reliable tool when modeling and stimulating flow and heat
transfer phenomena for designing process equipment without performing an actual experiment (Ali and Rohani,
1997). In a last decade, CFD has been considered as a powerful tool to help chemical engineering development.
Comsol multiphysics is a CFD software that is based on novel approach to computer aided modeling and
optimizing mixing, Modeling analysis involving Lagrangian and Fularian analysis for relative fluid stretching
and energy dissipation concepts for laminar and turbulent flows. One of the important advantages of using
comsol multiphysics in engineering application is the availability of the built in function in each application
mode. In addition, visualization of concentration profile of reactant and products within the reactor is possible.
Finally, with the above stated reasons, the use of CFD modeling to investigate how carbon deposits can affect
both the activity of catalysts as well as the flow of gas through a catalyst bed is inevitable.
2. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
www.iosrjournals.org 20 | Page
Concentration(mol/dm3
)
A CFD model will be developed to investigate the effect of carbon deposition on FCC catalyst in the
FCC reactor. In the first model, the influence of carbon deposition on catalyst activity will be considered. In the
second model, the effect that the carbon deposits have in fluid flow will also be investigated.
II. Research Methodology
This research, model and simulates carbon deposition on zeolite Y catalyst by catalytic decomposition of
methane to hydrogen in a FCC reactor using Computational Fluid Dynamics (CFD). Two models were
developed in this study. In the first model, the influence of carbon deposition on catalyst activity was
considered. In the second model, the effect that the carbon deposits have on the fluid flow was investigated. The
second simulation takes place in comsol multiphysics, taking both time and space dependencies into account.
The Fluid Catalytic Packed Bed Reactor
The model consists of the FCC reactor packed with zeolite Y catalyst where methane gas is
charged into it and it decomposed to carbon and hydrogen by catalytic cracking as shown in the
Figure 1. The coloured region is the zeolite packed region of the reactor while the plain region is the
region gas entry and exit from the reactor. A flow reactor is set up in 2D. Methane enters from the left
and reacts in the porous catalytic bed in the mid-section of the geometry. The model is geometry
modeling which is applicable to CFD and is represented as Figure 1
Timme (sec)
Figure 1: FCC Model showing the entering and exiting gas and the zeolite packed region of the
reactor.
Problem Statement
Fifty mol/m3
of methane gas is charged into an FCC reactor where it is flowing through a packed bed of zeolite
Y catalyst at temperature of 727°C. The methane is cracked on the zeolite catalyst producing carbon deposit on
the catalyst surface and hydrogen gas. The hydrogen gas exit the contacting bed at temperature of 727ºC.
Determine the following:
• The effect of carbon deposition on catalyst activity.
• The effect that the carbon deposit have on fluid flow taking both space and time dependencies into
account.
Geometry
The work models of carbon deposit on the surface of zeolite Y catalytic due to decomposition of methane to
carbon and hydrogen gas in packed bed reactor. The packed bed fluid catalytic reactor is represented by a 2D
geometry as seen in Figure 2.
Figure 2: The Packed Bed Fluid Catalytic Reactor Model
3. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
www.iosrjournals.org 21 | Page
Axis and Grid Settings
Table 1 Coordinate for drawing the geometry of the FCC packed bed reactor in 2D
Size Position
Width 1 X 0
Height 0.1 Y 0
Table 2 Coordinate for drawing the geometry of the packed bed region of the FCC packed bed reactor in
2D
Size Position
Width 0.4 x 0.4
Height 0.1 y 0
The coordinate for drawing the geometry of the FCC packed bed reactor and the catalyst packed region
of the reactor in 2D is shown in Table 1 and Table 2.
Chemistry
Methane decomposes over a Zeolite y catalyst according to the overall chemical reaction:
CH4 C + 2H2 1
The following reaction rate expression has been reported in the literature (Shariff et-al, 2004): relating the rate
of reaction and the concentration of various species is
𝑟 = 𝑘.
𝑝 𝐶𝐻 4−
𝑝2 𝐻2
𝐾 𝑝
(1+ 𝑘 𝐻 𝑝 𝐻2)2 2
Where
𝑘 = 2.31 ∗ 10−5
∗ exp(20.492 −
104200 𝐽/𝑚𝑜𝑙
𝑅 𝑔 𝑇
)
𝑚𝑜𝑙
𝑚3.𝑠.𝑏𝑎𝑟
𝑘 𝐻 = exp
163200𝐽
𝑚𝑜𝑙
𝑅𝑔 𝑇
− 22.426 (𝑏𝑎𝑟)−½
And
𝐾𝑝 = 5.088 ∗ 105
∗ exp(−
91200𝐽/𝑚𝑜𝑙
𝑅𝑔 𝑇
) 𝑏𝑎𝑟
Reactor model
The first model in Comsol Reaction Engineering Lab .was set up This model treats the isothermal
decomposition of methane (Equation 1) in a perfectly mixed reactor with constant volume. The species mass
balances are summarized by
𝑑 𝑐 𝑖
𝑑𝑡
= 𝑅𝑖 3
The rate term, Ri (mol/(m3
·s), takes into account the reaction stoichiometry, νi, the reaction rate, r (mol/(m3
·s),
and the catalyst activity, a:
𝑅𝑖 = 𝑉𝑖 𝑟𝑎 4
The mass balances of the reacting species are then
𝑑 𝑐 𝐶𝐻 4
𝑑𝑡
= −𝑟𝑎 5
4. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
www.iosrjournals.org 22 | Page
Concentration(mol/dm3
)𝑑 𝑐 𝑐
𝑑𝑡
= 𝑟𝑎 6
𝑑 𝑐 𝐻2
𝑑𝑡
= 2𝑟𝑎 7
The time dependence of the catalytic activity is expressed by the ODE
𝑝 = 𝑅𝑔 𝑇(𝐶 𝐶𝐻4 + 𝐶 𝐻2) 8
Where
𝑘 𝑎 = exp
135600𝐽
𝑚𝑜𝑙
𝑅𝑔 𝑇
− 32.007 (
𝑚3
𝑚𝑜𝑙
)3
. 𝑠
Solving the mass balances provides the evolution of the species concentrations over time. The fact that
carbon is in the solid phase is taken into account by removing its effect on gas phase physical properties. The
pressure in the reactor is a function of only the methane and hydrogen concentrations:
𝑝 = 𝑅𝑔 𝑇(𝐶 𝐶𝐻4 + 𝐶 𝐻2) 9
Space- and time-dependent Model
The second model is solved in comsol multiphysics and takes both fluid flow and the chemical
reaction into account.
The flow reactor is set up in 2D, as illustrated below:
Time (sec).
Figure 4: A flow reactor is set up in 2D. Methane enters from the left and reacts in the porous
catalytic bed
in the mid-section of the geometry.
Methane first flows through a free section of the reactor, and then encounters a porous catalytic bed where the
decomposition reaction takes place.
Momentum Balances
The flow in the free channel section is described by the Navier-Stokes equations:
𝜌
𝜕𝑈
𝜕𝑡
+ ∇. [−𝜂 ∇𝑢 + ∇𝑢) 𝑇
+ 𝜌𝐼 = 𝜌 𝑢. ∇ 𝑢
∇. 𝑢 = 0 10
Where ρ denotes density (kg/m3
), u represents the velocity (m/s), η is the dynamic viscosity (Pa·s)), and p refers
to the pressure (Pa). In the porous domain, the Brinkman equations govern the flow:
𝜌
𝜀 𝑝
.
𝜕𝑢
𝜕𝑡
+ ∇. [
𝜂
𝜀 𝑝
∇𝑢 + ∇𝑢 𝑇
+ 𝜌𝐼 = −
𝜂
𝑘
𝑢 11
Where Ԑp is the porosity and k denotes permeability (m2
) of the porous medium. As shown in Equation 10 and
11, the momentum-balance equations are closely related. The term on the right-hand side of the Navier-Stokes
5. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
www.iosrjournals.org 23 | Page
formulation corresponds to momentum transported by convection in free flow. In the Brinkman formulation,
this term is replaced by a contribution associated with the drag force experienced by the fluid as it flows through
a porous medium. Comsol multiphysics automatically combine free and porous-media flow to solve the
equations simultaneously.
The boundary conditions for the flow are:
𝑢. 𝑛 = 𝑢 𝑜 𝑖𝑛𝑙𝑒𝑡
𝑢 = 0 𝑤𝑎𝑙𝑙𝑠
𝜌 = 0 𝑜𝑢𝑡𝑙𝑒𝑡 12
The boundary condition for the inlet condition shows where the fluid enters the packed bud reactor and all other
point are walls.
Figure 3.5: The boundary condition for the inlet fluid.
U stand for the velocity (U0) at which the fluid enters the packed bed reactor. The boundary condition (U=0 for
wall) shows that there is no flow through the walls. The boundary condition P=0 for outlet shows that the
pressure of the gas is determined only at the outlet points. Mass transport in the reactor is described by the
diffusion-convection equations:
𝜕𝑐 𝑖
𝜕𝑡
+ ∇. −𝐷𝑖∇𝑐𝑖 + 𝑐𝑖 𝑢 = 𝑅𝑖 13
Where Di denotes the diffusion coefficient (m2
/s) and ci is the species concentration (mol/m3
). The term Ri
(mol/(m3
·s)) corresponds to the species’ net reaction rates.
In the free channel, the inlet conditions are equal to the inlet concentrations
𝑐 = 𝑐𝑖𝑛 14
At the outlet, the convective flux condition is used.
𝑛. −𝐷∇𝑐 = 0 15
All other boundaries, the insulating or symmetry condition are used
𝑛. −𝐷∇𝑐 + 𝑐𝑢 = 0 16
Balance for void fraction
The void fraction of the catalytic bed decreases as carbon is deposited. This, in turn, affects the flow
through the reactor. A balance for the void fraction, or porosity, of the bed is given by (Comsol, 2008):
𝑑𝜀
𝑑𝑡
= −
𝜀𝑟
𝑀 𝑐 𝜌 𝑠𝑜𝑜𝑡
17
This equation can be implemented in the PDE, General Form application mode of comsol multiphysics,
resulting in porosity distribution across the catalytic bed as a function of time. The initial porosity of the bed is
taken to be ε = 0.4 (Comsol, 2008).The porosity is related to the permeability of the porous domain by the
expression (Borisova and Adler, 2005):
𝑘 = 𝑘 𝑜 (
𝜀
𝜀 𝑜
)3.55
18
In this way, the porosity balance couples the mass and momentum balances describing the reacting system.
Properties of the fluid
The material properties of the fluid specified in Comsol (2008). For the reacting fluid and product is
shown in Table 3.
Uo
U ₌ o
P ₌ o
6. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
www.iosrjournals.org 24 | Page
Concentration
(mol/dm3
)
Table 3 The transport and kinetic properties specified in Comsol for the reacting Fluid and product.
Name Expression Description
u_in 0.667[mm/s] Average inlet velocity
c_CH4in 50[mol/m^3] Inlet concentration, CH4
c_H2in 0[mol/m^3] Inlet concentration, H2
ρ 1[kg/m^3] Density, fluid
µ 1e-5[Pa*s] Dynamic viscosity, fluid
Ԑ 0.47 Porosity of zeolite Y catalyst bed
kappa 1.39e-9[m^2] Permeability of clean zeolite Y
ρ_soot 4e3[kg/m^3] Density of soot deposits
M_C 12.011[g/mol] Molar weight of carbon
D_CH4 1e-6[m^2/s] Diffusion coefficient, CH4
D_H2 4e-6[m^2/s] Diffusion coefficient, H2
k_eff 0.1 Effectiveness factor
u_in 0.667[mm/s] Average inlet velocity
c_CH4in 50[mol/m^3] Inlet concentration, CH4
c_H2in 0[mol/m^3] Inlet concentration, H2
ρ 1[kg/m^3] Density, fluid
Meshing
In this step, the computational domain is divided into small simple shapes (known as
elements) to help solve the governing equations numerically. The initialize mesh created in
comsol is shown in Figure 3.4
Time (sec)
Figure 5: The Initialize mesh of the FCC packed bed reactor surface geometry.
The mesh statistics is given below:
Table 4 Mesh statistics
Mesh Statistics Values
Number of degree of freedom 131860
Number of mesh points 7306
Number of elements 13580
Number of boundary element 1130
Number of vertex element 8
Minimum element quality 0.7994
Element area ratio 0.0090
7. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
www.iosrjournals.org 25 | Page
Time step
The time problem solved is transient type and hence a time interval of 1000 sec was specified at time interval of
1 sec interval was also specified in comsol.
Solver
Comsol use the Boundary Difference Formula (BDF) to solve the set of algebraic equations obtained from the
original partial differential equations in the processing stage where there are a number of different solvers
available. Comsol set the minimum and maximum BDF order to 1 and 5 respectively. Elimination was selected
in the constraint standing order while Automatic was selected in the Null-space function.
Tolerance
In order to control the error in the calculated solution, relative and absolute tolerance of 0.01 and 0.001 were
specified in Comsol.
Processing
The governing partial differential equations are transformed into a system of algebraic equations and the
unknown values (concentration) were determined.
Post processing
This step involves visualizing the solution obtained at the processing where the concentration in mol/mm3
was
specified for each parametric study of methane, hydrogen and carbon deposited. The type of plot selected in the
plot parameter is the surface plot.
Numerical methods
All the governing equations were numerically solved in comsol multiphysics (version 3.5) using a stationary
solver with a direct (UMFPACK) linear solver system. The residual convergence was limited to 10-6
for all
variables. Grid independence was achieved at 57 000 finite elements (Figure 4), after which the change in the
maximum temperature was less than 0.1%, change in maximum velocity was less than 1%, concentration was
less than 0.1%.
III. Result And Discussion
Results
The results of the computational fluid dynamics of transport and reaction on the active surface of Zeolite Y
catalyst in an FCC riser are shown below:
Figure 6: The concentration transients of methane decomposition over a zeolite Y catalyst.
8. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
www.iosrjournals.org 26 | Page
Concentration(mol/dm3
)
Figure 7: The variation of reactor pressure without catalyst deactivation taking place.
Figure 8: Catalyst activity drops off as carbon deposits at the catalyst surface.
Figure 9: Concentration transients of methane, hydrogen, and deposited carbon with no deactivation present
(solid lines) and with deactivation taken into account (dashed lines).
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Velocity(mm/s)
Figure 10: The variation of velocity flow field in the 2D reactor domain.
x – coordinate (m)
Figure 11: The variation of gas velocity along the reactor centerline.
Figure 12: Methane and hydrogen concentrations as a function of the bed position.
10. Modeling Of Carbon Deposit From Methane Gas On Zeolite Y Catalyst Activity In A Packed Bed
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Pressure(Pa)
Pressure(Pa)
Figure 13: Permeability of packed catalytic bed as the decomposition of methane proceeds for
1,000s.
Then time interval between each line is 1.
x – coordinate (m)
Figure 14: Distribution of pressure as a non reacting gas passes a clean catalyst be Pressure
distribution across
the 2D reactor domain.
Figure 15: Pressure drop along the packed catalyst bed.
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Pressure(Pa)
Pressure(Pa)
x – coordiinate (m)
Figure 16: Distribution of pressure when methane decomposition has been allowed to occur for 1000 s
(Pressure distribution across the 2D reactor domain).
Figure 17: Distribution of pressure when methane decomposition has been allowed to occur for 1000
s
(Pressure drop along the packed catalyst bed).
x – coordinate (m)
Figure 18: Distribution of pressure when methane decomposition has been allowed to occur for 1000 s
(COMSOL, 2008)
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Discussion of Results
Figure 6 shows the concentration profile of methane decomposition over a zeoelite Y catalyst the plot
shows that as the time of methane decomposition increase from 0 to 1000 s, the concentration of carbon and
hydrogen formed increase from 0 to 42 mol/dm3
. For hydrogen and carbon increase from 0 to 21mol/dm³ this
shows that the formation of hydrogen is faster than that of carbon. Figure 4.1 also shows that as a reaction time
increase from 0 to 1000 s the methane concentration decrease from 50 to 29 mol/dm³. This shows that methane
decomposition take place in the reactor. Also from Figure 6 the carbon deposition on catalyst is faster from
time 0 to 400 s above 500 s carbon deposition is lower.
Figure 7 shows the pressure of the gas entering the reactor before the deposition of the catalyst. The
pressure increase from 0 to 1000 s as the pressure increase from 3.6 E-5 pa to 5.6 E-5 pa. Figure 7 also shows
that the pressure increase was faster from period of 0 to 500 s but slower from time interval of 100 to 1000 s
Figure 8 shows the variation the catalyst activity with respect to time Figure 8 shows that the catalyst
activity drop off as carbon deposit at the catalyst surface this shows that the catalyst deposit affect the
performance of the catalyst.
Figure 9 shows the concentration transients of methane hydrogen with catalyst deactivation included in
the model and when catalyst deactivation was not included in the model. The dashed line shows when catalyst
deactivation was taken into an account and solid line shows when catalyst deactivation was not taken into an
account. Figure 9 shows that the concentration of carbon and hydrogen formed is less when catalyst
deactivation is taken into an account compare to when catalyst deactivation was taken into an account. It can be
deduce from the above discussion that carbon deposit on the catalyst affect the performance of the catalyst.
The following results concern a space- and time-dependent model simulated in comsolmultiphysics.
Methane decomposition occurs in a porous region where solid catalyst particles are packed. Figures 10 and 11
show the velocity field across the reactor prior to carbon deposition. The 2D plot in Figure 10 shows that the
velocity profile is parabolic in the free channel sections and close to constant in the porous domain. The line plot
in Figure 11 shows the velocity along the reactor centerline.
Reactions take place in the packed catalytic bed located in the reactor mid section. Figure 12 shows the
concentration profiles along the centerline of the bed. The methane and hydrogen concentrations are equal
approximately 0.18 m into the bed. Figures 10 and 11 show that the velocity in the bed is about 0.67 mm/s,
corresponding to a residence time of 270 s. This result agrees with the findings from the reactor simulation,
shown in Figures 6 and 7. Now, consider the effects as methane is constantly supplied to the reactor for 1000
seconds. The initial permeability is a constant 1.39·10−9
m2
across the bed. The permeability at the front end of
the bed changes by four orders of magnitude during the first 1000 s of carbon deposition. As carbon deposits in
the reacting bed, the pressure distribution across the reactor is affected. Figures 14 and 15 shows small, linear
pressure drop as unreacting gas passes through a clean catalyst bed. Figures 16, 17 and 18 show the pressure
distribution across the reactor after methane decomposition has occurred for 1000 s. The pressure drop is
notably greater and occurs across the first 10 cm of the bed.
Comsol also carried out similar work on methane decomposition on Ni/Al2O3 catalyst which motivated
this work to see the effect of carbon deposition on a different catalyst. The catalyst considered in this work is
Zeolite Y catalyst. The result obtained in this work was also compared to that obtained in literature (Sharif, et al
2008) and the two results are in agreement.
IV. Conclusion
This research work demonstrate the use of computational fluid dynamic (CFD) to examine the effects of
carbon deposit on fluid catalytic cracking (FCC) catalysts and the effects of the fluid flow in fluid catalytic
cracking FCC reactor. Reaction was carried out in the packed catalytic bed located in the reactor’smid section
with methane and hydrogen of equal concentrations of 0.18m in bed. Methane decomposition occurs in a porous
region where solid catalyst particles are packed. Carbon was deposited on Zeolite Y catalyst due to
decomposition of methane to carbon hydrogen in a packed bed FCC reactor. There was a moderate drop in
activity of the Zeolite Y catalyst leading to a largely unaffected overall process for decomposition of methane to
carbon hydrogen in a packed bed FCC reactor. The permeability at the front end of the bed changes by four
orders of magnitude during the first 1000 s of carbon deposition.
Acknowledgements
From him (Allah) we come and to him we shall return (Allah). I believe in him, I worship him, I magnify
his position, I glorify his name, I bear withness that there is no diety worthy of worship except him and that
prophet Mohammad (PBUH) is his final messenger and I sincerely thank him for his unlimited strenght giving
to me to overcome this challenge.
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