1) The Pt supported on mesoporous silicate FSM-16 showed high and stable catalytic activity for the hydrodesulfurization of thiophene at 350°C and this activity was higher than that of commercial CoMo/A120 3 catalysts.
2) Among noble metal/FSM-16 catalysts, Pt/FSM-16 showed the highest activity for the hydrodesulfurization of thiophene. The optimal loading of Pt on FSM-16 was determined to be 5 wt%.
3) The activity of Pt/FSM-16 decreased temporarily when hydrogen sulfide was introduced but was restored after cutting off the introduction, indicating that hydrogen sulfide is reversibly adsorbed on the Pt/FSM
The document discusses various methods for modifying solid acids like zeolites to increase the selectivity and yield of p-xylene in toluene methylation reactions. Silylation of zeolites using compounds like TEOS reduces pore size and external acid sites. Loading metals like Mg, La, and Pt improves stability and selectivity. Using co-crystalline zeolites or superacids supported on clays also enhances p-xylene production. Reaction conditions like lower contact times below 0.1 seconds and suitable binders maximize selectivity.
This chapter examines the use of metal ion-exchanged zeolites as solid acid catalysts for the Prins reaction to synthesize nopol. Various zeolites were prepared by ion exchanging them with metals like Zn2+, Fe2+, Ni2+, Cu2+ and Sr2+. The ion-exchanged zeolites were then tested as catalysts for the Prins condensation reaction of β-pinene and paraformaldehyde to produce nopol. This is the first study examining zeolites and their ion-exchanged forms as catalysts for the Prins reaction. The goal is to understand the effect of different metal ion exchanges on the activity and selectivity of zeolite catalysts for this reaction
The role of protons in the epoxidation of olefins using metal catalysts and oxidants like H2O2 was studied. Three key findings:
1) Protons play an important role in cleaving the O-O bond of hydroperoxides to form reactive metal-oxo intermediates.
2) Protons increase the reactivity of these metal-oxo species towards olefins, facilitating epoxide formation.
3) Reactions performed with H2SO4 as a bronsted acid produced epoxides in higher yields and enantioselectivities compared to without acid. Isotopic labelling studies supported a metal-oxo intermediate.
Development of Mesoporous Materials and Noble Metal Based Hydrodesulfurizatio...Lebong Andalaluna
The document discusses the development of mesoporous materials and noble metal-based hydrodesulfurization catalysts. It was found that Pt supported on acidic mesoporous materials like SiAlMCM-41 showed high catalytic activity for thiophene hydrodesulfurization that was higher than commercial CoMo/Al2O3 catalysts. Pt supported on moderately acidic SiAlMCM-41 (Si/Al=15) exhibited particularly high activity. The acidic properties of the MCM-41 support and the spillover hydrogen on Pt particles in Pt/MCM-41 catalysts were found to play an important role in thiophene hydrodesulfurization.
Phase-transfer catalysts facilitate the transfer of reactants between immiscible liquid phases, allowing reactions to occur. They are commonly used quaternary ammonium or phosphonium salts. The catalyst transports one reactant from the aqueous phase to the organic phase where it can undergo a nucleophilic substitution reaction. This allows reactions to be carried out using cheaper and more environmentally friendly reagents like NaOH instead of organic solvents. Phase-transfer catalysis finds applications in industries like pharmaceuticals, perfumes, polymers, and pesticides by enabling mild reaction conditions.
This document provides an overview of chiral ligands, Ziegler-Natta catalysts, and examples of homogeneous catalysis used in drug synthesis. It discusses how chiral ligands form asymmetric catalysts that can induce chirality in substrates, producing one enantiomer in excess. Ziegler-Natta catalysts are formed from a transition metal and organometallic compound used to polymerize olefins like polyethylene. Examples shown include the synthesis of L-DOPA, (R)-naproxen, and (S)-ibuprofen using chiral catalysts like Rh, Ru, and Rh-BINAP.
The document discusses various methods for modifying solid acids like zeolites to increase the selectivity and yield of p-xylene in toluene methylation reactions. Silylation of zeolites using compounds like TEOS reduces pore size and external acid sites. Loading metals like Mg, La, and Pt improves stability and selectivity. Using co-crystalline zeolites or superacids supported on clays also enhances p-xylene production. Reaction conditions like lower contact times below 0.1 seconds and suitable binders maximize selectivity.
This chapter examines the use of metal ion-exchanged zeolites as solid acid catalysts for the Prins reaction to synthesize nopol. Various zeolites were prepared by ion exchanging them with metals like Zn2+, Fe2+, Ni2+, Cu2+ and Sr2+. The ion-exchanged zeolites were then tested as catalysts for the Prins condensation reaction of β-pinene and paraformaldehyde to produce nopol. This is the first study examining zeolites and their ion-exchanged forms as catalysts for the Prins reaction. The goal is to understand the effect of different metal ion exchanges on the activity and selectivity of zeolite catalysts for this reaction
The role of protons in the epoxidation of olefins using metal catalysts and oxidants like H2O2 was studied. Three key findings:
1) Protons play an important role in cleaving the O-O bond of hydroperoxides to form reactive metal-oxo intermediates.
2) Protons increase the reactivity of these metal-oxo species towards olefins, facilitating epoxide formation.
3) Reactions performed with H2SO4 as a bronsted acid produced epoxides in higher yields and enantioselectivities compared to without acid. Isotopic labelling studies supported a metal-oxo intermediate.
Development of Mesoporous Materials and Noble Metal Based Hydrodesulfurizatio...Lebong Andalaluna
The document discusses the development of mesoporous materials and noble metal-based hydrodesulfurization catalysts. It was found that Pt supported on acidic mesoporous materials like SiAlMCM-41 showed high catalytic activity for thiophene hydrodesulfurization that was higher than commercial CoMo/Al2O3 catalysts. Pt supported on moderately acidic SiAlMCM-41 (Si/Al=15) exhibited particularly high activity. The acidic properties of the MCM-41 support and the spillover hydrogen on Pt particles in Pt/MCM-41 catalysts were found to play an important role in thiophene hydrodesulfurization.
Phase-transfer catalysts facilitate the transfer of reactants between immiscible liquid phases, allowing reactions to occur. They are commonly used quaternary ammonium or phosphonium salts. The catalyst transports one reactant from the aqueous phase to the organic phase where it can undergo a nucleophilic substitution reaction. This allows reactions to be carried out using cheaper and more environmentally friendly reagents like NaOH instead of organic solvents. Phase-transfer catalysis finds applications in industries like pharmaceuticals, perfumes, polymers, and pesticides by enabling mild reaction conditions.
This document provides an overview of chiral ligands, Ziegler-Natta catalysts, and examples of homogeneous catalysis used in drug synthesis. It discusses how chiral ligands form asymmetric catalysts that can induce chirality in substrates, producing one enantiomer in excess. Ziegler-Natta catalysts are formed from a transition metal and organometallic compound used to polymerize olefins like polyethylene. Examples shown include the synthesis of L-DOPA, (R)-naproxen, and (S)-ibuprofen using chiral catalysts like Rh, Ru, and Rh-BINAP.
BY AMIT SHAH & SOHAM MULE, F.Y.B. PHARM, KMKCP.
PTC (PHASE TRANSFER CATALYSIS) A SMALL TOPIC IN 2ND SEMESTER OF B.PHARM IN POC - 1 UNDER THE TOPIC SN REACTIONS. PTC FAVOURS SN2 REACTIONS.
This document provides an overview of homogeneous catalysis and biocatalysis. It discusses various homogeneous catalysts including Wilkinson's catalyst, Ziegler-Natta catalysts, and catalysts used in hydrogenation and hydroformylation reactions. It also discusses the use of enzymes in organic synthesis, including hydrolysis reactions and the synthesis of tartaric acids. Finally, it covers immobilized enzymes and various methods for enzyme immobilization.
Carbon–Sulfur Bond Formation of Challenging Substrates at Low Temperature by ...DrMAdamSayah
Pd-PEPPSI-IPent catalyst allows for sulfination reactions of challenging substrates to occur at low temperatures. Reactions proceed smoothly at 40°C for a variety of aryl and heteroaryl halides with aryl, alkyl, and silyl sulfides. The catalyst shows unprecedented reactivity, performing couplings not previously achieved, such as with strongly deactivated substrates. Reactions are also found to occur rapidly at room temperature.
The document discusses direct fluorination reactions in microreactors. It proposes acetylating alcohols prior to fluorination to protect the alcohol group. The fluorination would take place in a microreactor using a gas-liquid system with elemental fluorine and nitrogen. Previous attempts at direct fluorination of alcohols and polyhedral boranes in batch reactors are described. The document outlines characterization techniques that could be used to analyze products from the proposed microreactor fluorination experiments.
Phase transfer catalysis involves using a catalyst to transfer a reactant from one immiscible liquid phase to another where the reaction takes place. Common phase transfer catalysts are quaternary ammonium and phosphonium salts. The catalyst forms an ion pair with the reactant anion, transporting it into the organic phase where it undergoes nucleophilic substitution or other reactions. Phase transfer catalysis allows reactions between ions and organic molecules that would otherwise not interact due to being in separate phases. It has many applications in organic synthesis and pharmaceutical manufacturing.
Carboxy-terminal Degradation of Peptides using Perfluoroacyl Anhydrides : C-T...Keiji Takamoto
This document describes a new method for determining the carboxy-terminal (C-terminal) amino acid sequence of peptides using perfluoroacyl anhydride vapor. Exposure of peptides to the vapor at -20°C for 0.5-1 hours sequentially degrades the peptide from the C-terminus. Analysis of the truncated peptide fragments by fast-atom-bombardment mass spectrometry allows determination of the C-terminal sequence based on mass differences. The method provides C-terminal sequence information as a complement to the common Edman degradation method for amino-terminal sequencing. The perfluoroacyl anhydride vapor method results in more extensive C-terminal degradation than a previous method using perfluoric acid
This presentation will help you understand the concise summary of Benzodiazepines from the Medicinal Chemistry point of view. it is a brief and concise summary so if there is any mistake, you can point out it to me or make corrections yourself.
thanks
Amjad Anwar
IOSRPHR(www.iosrphr.org) IOSR Journal of Pharmacyiosrphr_editor
The document describes the synthesis and pharmacological screening of benzoxazole derivatives as potential anti-inflammatory agents. A series of N'-[substituted sulfonyl]-1,3-benzoxazole-5-carbohydrazide compounds were synthesized using a multi-step synthesis route involving nitration, reduction, acid reactions, and substitution. The compounds were characterized using methods like IR, 1H NMR and mass spectroscopy. The compounds were then screened for anti-inflammatory activity and approximate toxicity. Eight compounds were synthesized with different R1 and R2 substituents on the benzoxazole ring. Preliminary pharmacological screening found some compounds showed promising anti-inflammatory activity with low toxicity, making them potential
Homogeneous catalysis involves metal complexes in the same phase as reactants, usually liquid. It has advantages like high selectivity and mild reaction conditions. Key aspects include the metal's oxidation state and ligands used. Ligands affect catalysis electronically by donating or accepting electrons from the metal. They also impact catalysis sterically based on their size. The catalytic cycle involves the metal complex having vacant sites for substrates to coordinate through steps like oxidative addition and reductive elimination.
This document describes N-substituted sultams and a process for their production. It involves reacting a sultam with an organic halide such as an alkyl halide, aralkyl halide, carboxylic acid halide, or sulphonic acid halide. The sultam is first converted to its alkali metal salt, which is then reacted with the organic halide. This produces an N-substituted sultam and an alkali metal halide byproduct. The N-substituted sultams can be isolated by filtering and recrystallizing the reaction mixture. Examples are given of suitable sultams and organic halides for this reaction.
1) Boronic acids were shown to be potent competitive inhibitors of the nitrile hydratase enzyme from Pseudonocardia thermophila (PtNHase).
2) X-ray crystallography revealed that the sulfenic acid ligand of the active site cysteine attacks and forms a covalent bond with the boron atom of bound boronic acid inhibitors, representing a potential reaction intermediate.
3) A new mechanism is proposed for nitrile hydration by nitrile hydratases wherein the sulfenic acid ligand acts as the catalytic nucleophile.
The document discusses hydrogen peroxide stabilization using chemical stabilizers. It aims to find a stabilizer that restricts the auto-decomposition of hydrogen peroxide without catalytic poisoning. Stabilizers are chemical compounds that delay the auto-catalytic decomposition of hydrogen peroxide, improving storage stability. Sodium stannate and 8-hydroxyquinoline are discussed as effective stabilizers that deactivate catalytic metal ions and increase the shelf life of hydrogen peroxide solutions. The decomposition rate of hydrogen peroxide is analyzed under various conditions like temperature, pH, concentration, and presence of catalytic impurities. Direct titration and gas evolution methods are also described to determine the decomposition rate.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This work describes kinetic studies of the catalytic oxidation of thiols (RSHs) found in kerosene to disulphides
using a magnetically separable iron oxide coated Mg-Al layered double hydroxide supported tetra-sulphonated
cobalt phthalocyanine (CoPcS/LDH@Fe3O4) catalyst in an alkali-free environment. Using 1-octanethiol as a representative
RSH, we investigated the effects of different experimental parameters on RSH oxidation kinetics, including
catalyst concentration, temperature (30–60 °C), and initial thiol concentration ([RSH]0, 100–300 ppm).
The catalyst concentration was varied so that the [RSH]0/[Co]tot molar ratio ranged from 45 to 180. Based on
the results, we propose a mechanistic rate expression to explain the observed oxidation of RSH in the presence
of the CoPcS/LDH@Fe3O4 catalyst. The proposed rate law resembles double substrate Michaelis-Menten kinetics,
however, for commonly encountered industrial conditions, we were able to simplify it to a linear form. This rate
law for RSH oxidation can be used to design industrial reactors for an alkali-free sweetening process.
This document discusses different types of catalysis including homogeneous catalysis, heterogeneous catalysis, and enzyme catalysis. It explains that catalysts speed up chemical reactions by lowering the activation energy without being consumed in the process. Catalysts can be solids (heterogeneous) or the same phase as reactants (homogeneous). Enzymes are protein catalysts that use active sites to specifically catalyze reactions in living cells. Theories of catalysis include intermediate compound formation and adsorption of reactants onto catalyst surfaces. Acid-base catalysis involves acids or bases donating or accepting protons to form reactive intermediates.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This research article studies the kinetics of catalytic oxidation of thiols to disulfides using a novel magnetically separable catalyst. The catalyst contains cobalt phthalocyanine grafted onto an iron oxide-coated layered double hydroxide supported on magnetic iron oxide nanoparticles. Experiments were conducted to investigate the effects of various parameters on thiol oxidation kinetics, including catalyst concentration, temperature, and initial thiol concentration. Kinetic data was analyzed to propose a rate law that could be used to design industrial reactors for an alkali-free sweetening process.
The Fischer-Tropsch process converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. It has been used commercially to produce fuels from coal and natural gas. Notable implementations include use by Nazi Germany during WWII and large-scale plants still operated by Sasol in South Africa, which uses coal and natural gas as feedstocks. The process involves catalytic chemical reactions, typically using iron or cobalt catalysts, to synthesize liquid fuels like diesel.
Kinetics of Ruthenium(III) Catalyzed and Uncatalyzed Oxidation of Monoethanol...Ratnakaram Venkata Nadh
Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide
(NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate
and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS,
a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate
concentration and decreased with an increase in the perchloric acid concentration. This indicates that free
amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate,
which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the
medium decreases the kinetic rate pointing out that these are dipole—dipole reactions. A relatively higher
oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A
suitable mechanism consistent with the observations has been proposed and a rate law has been derived to
explain the kinetic orders.
The document provides an introduction to using social media for business purposes. It outlines five phases of social media marketing: discover, strategize, skills, execute, and maintenance. It also discusses the differences between Facebook profiles and pages, with pages being more suitable for businesses since they allow features like accepting followers, analytics, and advertising. Steps are provided for setting up business pages and accounts on Facebook and Twitter, along with tips for posting engaging content and using hashtags. Recommended resources for ongoing social media education and management are also included.
BY AMIT SHAH & SOHAM MULE, F.Y.B. PHARM, KMKCP.
PTC (PHASE TRANSFER CATALYSIS) A SMALL TOPIC IN 2ND SEMESTER OF B.PHARM IN POC - 1 UNDER THE TOPIC SN REACTIONS. PTC FAVOURS SN2 REACTIONS.
This document provides an overview of homogeneous catalysis and biocatalysis. It discusses various homogeneous catalysts including Wilkinson's catalyst, Ziegler-Natta catalysts, and catalysts used in hydrogenation and hydroformylation reactions. It also discusses the use of enzymes in organic synthesis, including hydrolysis reactions and the synthesis of tartaric acids. Finally, it covers immobilized enzymes and various methods for enzyme immobilization.
Carbon–Sulfur Bond Formation of Challenging Substrates at Low Temperature by ...DrMAdamSayah
Pd-PEPPSI-IPent catalyst allows for sulfination reactions of challenging substrates to occur at low temperatures. Reactions proceed smoothly at 40°C for a variety of aryl and heteroaryl halides with aryl, alkyl, and silyl sulfides. The catalyst shows unprecedented reactivity, performing couplings not previously achieved, such as with strongly deactivated substrates. Reactions are also found to occur rapidly at room temperature.
The document discusses direct fluorination reactions in microreactors. It proposes acetylating alcohols prior to fluorination to protect the alcohol group. The fluorination would take place in a microreactor using a gas-liquid system with elemental fluorine and nitrogen. Previous attempts at direct fluorination of alcohols and polyhedral boranes in batch reactors are described. The document outlines characterization techniques that could be used to analyze products from the proposed microreactor fluorination experiments.
Phase transfer catalysis involves using a catalyst to transfer a reactant from one immiscible liquid phase to another where the reaction takes place. Common phase transfer catalysts are quaternary ammonium and phosphonium salts. The catalyst forms an ion pair with the reactant anion, transporting it into the organic phase where it undergoes nucleophilic substitution or other reactions. Phase transfer catalysis allows reactions between ions and organic molecules that would otherwise not interact due to being in separate phases. It has many applications in organic synthesis and pharmaceutical manufacturing.
Carboxy-terminal Degradation of Peptides using Perfluoroacyl Anhydrides : C-T...Keiji Takamoto
This document describes a new method for determining the carboxy-terminal (C-terminal) amino acid sequence of peptides using perfluoroacyl anhydride vapor. Exposure of peptides to the vapor at -20°C for 0.5-1 hours sequentially degrades the peptide from the C-terminus. Analysis of the truncated peptide fragments by fast-atom-bombardment mass spectrometry allows determination of the C-terminal sequence based on mass differences. The method provides C-terminal sequence information as a complement to the common Edman degradation method for amino-terminal sequencing. The perfluoroacyl anhydride vapor method results in more extensive C-terminal degradation than a previous method using perfluoric acid
This presentation will help you understand the concise summary of Benzodiazepines from the Medicinal Chemistry point of view. it is a brief and concise summary so if there is any mistake, you can point out it to me or make corrections yourself.
thanks
Amjad Anwar
IOSRPHR(www.iosrphr.org) IOSR Journal of Pharmacyiosrphr_editor
The document describes the synthesis and pharmacological screening of benzoxazole derivatives as potential anti-inflammatory agents. A series of N'-[substituted sulfonyl]-1,3-benzoxazole-5-carbohydrazide compounds were synthesized using a multi-step synthesis route involving nitration, reduction, acid reactions, and substitution. The compounds were characterized using methods like IR, 1H NMR and mass spectroscopy. The compounds were then screened for anti-inflammatory activity and approximate toxicity. Eight compounds were synthesized with different R1 and R2 substituents on the benzoxazole ring. Preliminary pharmacological screening found some compounds showed promising anti-inflammatory activity with low toxicity, making them potential
Homogeneous catalysis involves metal complexes in the same phase as reactants, usually liquid. It has advantages like high selectivity and mild reaction conditions. Key aspects include the metal's oxidation state and ligands used. Ligands affect catalysis electronically by donating or accepting electrons from the metal. They also impact catalysis sterically based on their size. The catalytic cycle involves the metal complex having vacant sites for substrates to coordinate through steps like oxidative addition and reductive elimination.
This document describes N-substituted sultams and a process for their production. It involves reacting a sultam with an organic halide such as an alkyl halide, aralkyl halide, carboxylic acid halide, or sulphonic acid halide. The sultam is first converted to its alkali metal salt, which is then reacted with the organic halide. This produces an N-substituted sultam and an alkali metal halide byproduct. The N-substituted sultams can be isolated by filtering and recrystallizing the reaction mixture. Examples are given of suitable sultams and organic halides for this reaction.
1) Boronic acids were shown to be potent competitive inhibitors of the nitrile hydratase enzyme from Pseudonocardia thermophila (PtNHase).
2) X-ray crystallography revealed that the sulfenic acid ligand of the active site cysteine attacks and forms a covalent bond with the boron atom of bound boronic acid inhibitors, representing a potential reaction intermediate.
3) A new mechanism is proposed for nitrile hydration by nitrile hydratases wherein the sulfenic acid ligand acts as the catalytic nucleophile.
The document discusses hydrogen peroxide stabilization using chemical stabilizers. It aims to find a stabilizer that restricts the auto-decomposition of hydrogen peroxide without catalytic poisoning. Stabilizers are chemical compounds that delay the auto-catalytic decomposition of hydrogen peroxide, improving storage stability. Sodium stannate and 8-hydroxyquinoline are discussed as effective stabilizers that deactivate catalytic metal ions and increase the shelf life of hydrogen peroxide solutions. The decomposition rate of hydrogen peroxide is analyzed under various conditions like temperature, pH, concentration, and presence of catalytic impurities. Direct titration and gas evolution methods are also described to determine the decomposition rate.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This work describes kinetic studies of the catalytic oxidation of thiols (RSHs) found in kerosene to disulphides
using a magnetically separable iron oxide coated Mg-Al layered double hydroxide supported tetra-sulphonated
cobalt phthalocyanine (CoPcS/LDH@Fe3O4) catalyst in an alkali-free environment. Using 1-octanethiol as a representative
RSH, we investigated the effects of different experimental parameters on RSH oxidation kinetics, including
catalyst concentration, temperature (30–60 °C), and initial thiol concentration ([RSH]0, 100–300 ppm).
The catalyst concentration was varied so that the [RSH]0/[Co]tot molar ratio ranged from 45 to 180. Based on
the results, we propose a mechanistic rate expression to explain the observed oxidation of RSH in the presence
of the CoPcS/LDH@Fe3O4 catalyst. The proposed rate law resembles double substrate Michaelis-Menten kinetics,
however, for commonly encountered industrial conditions, we were able to simplify it to a linear form. This rate
law for RSH oxidation can be used to design industrial reactors for an alkali-free sweetening process.
This document discusses different types of catalysis including homogeneous catalysis, heterogeneous catalysis, and enzyme catalysis. It explains that catalysts speed up chemical reactions by lowering the activation energy without being consumed in the process. Catalysts can be solids (heterogeneous) or the same phase as reactants (homogeneous). Enzymes are protein catalysts that use active sites to specifically catalyze reactions in living cells. Theories of catalysis include intermediate compound formation and adsorption of reactants onto catalyst surfaces. Acid-base catalysis involves acids or bases donating or accepting protons to form reactive intermediates.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This research article studies the kinetics of catalytic oxidation of thiols to disulfides using a novel magnetically separable catalyst. The catalyst contains cobalt phthalocyanine grafted onto an iron oxide-coated layered double hydroxide supported on magnetic iron oxide nanoparticles. Experiments were conducted to investigate the effects of various parameters on thiol oxidation kinetics, including catalyst concentration, temperature, and initial thiol concentration. Kinetic data was analyzed to propose a rate law that could be used to design industrial reactors for an alkali-free sweetening process.
The Fischer-Tropsch process converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. It has been used commercially to produce fuels from coal and natural gas. Notable implementations include use by Nazi Germany during WWII and large-scale plants still operated by Sasol in South Africa, which uses coal and natural gas as feedstocks. The process involves catalytic chemical reactions, typically using iron or cobalt catalysts, to synthesize liquid fuels like diesel.
Kinetics of Ruthenium(III) Catalyzed and Uncatalyzed Oxidation of Monoethanol...Ratnakaram Venkata Nadh
Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide
(NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate
and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS,
a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate
concentration and decreased with an increase in the perchloric acid concentration. This indicates that free
amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate,
which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the
medium decreases the kinetic rate pointing out that these are dipole—dipole reactions. A relatively higher
oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A
suitable mechanism consistent with the observations has been proposed and a rate law has been derived to
explain the kinetic orders.
The document provides an introduction to using social media for business purposes. It outlines five phases of social media marketing: discover, strategize, skills, execute, and maintenance. It also discusses the differences between Facebook profiles and pages, with pages being more suitable for businesses since they allow features like accepting followers, analytics, and advertising. Steps are provided for setting up business pages and accounts on Facebook and Twitter, along with tips for posting engaging content and using hashtags. Recommended resources for ongoing social media education and management are also included.
The document describes the memory management unit (MMU) of the LatticeMico32 processor. It has 1024 entries each for the instruction and data translation lookaside buffers (ITLB and DTLB). It supports adding, updating, and invalidating TLB entries as well as flushing the TLBs using control and status registers. The MMU can be activated and deactivated by setting bits in the processor status word register to enable virtual memory and memory protection capabilities.
The document provides instructions for a collaborative research project on gender studies. It outlines the assignment requirements, including choosing a topic related to gender from a film clip, formulating a research question, researching the topic by finding 5 scholarly sources per person, and creating an annotated bibliography with bibliographic entries and summaries of the sources. Students are to analyze and argue a position, rather than just stating facts, on their chosen topic as it relates to the film clip.
Une introduction à git, présentée par Yann Sionneau aux membres de l'association MiNET et du club INTech.
La qualité du lecteur PDF sur slideshare laissant à désirer, je vous invite à télécharger le PDF plutôt que de le lire sur le site.
Social Media Marketing for Voice-Over Artistsggsmvt
This document provides guidance on using social media to market voice over artist services. It discusses setting up and optimizing profiles on Facebook, Twitter, LinkedIn and blogs to engage customers. Tips include using relevant hashtags, keywords, links and posting regularly while customizing profiles across platforms for consistency. Maintaining an informative website and monitoring analytics can also help voice over artists succeed with social media marketing.
This document outlines professional development topics including SMART training to support ongoing investment and identify knowledge needs, a writing program focusing on the current grade level program and integrating 6+1 traits with a textbook, enVision math training on district support and pacing to grade level needs, and defining student engagement at both general and grade level levels.
Disposition Pattern of Sulphur Functional Groups in High Sulphur Ledo Coals o...IOSR Journals
This document discusses a study of the distribution of sulfur functional groups in high-sulfur Ledo coals from Assam, India using Temperature Programmed Reduction (TPR). TPR studies were conducted on Ledo coal and model sulfur compounds between 190-6200°C in hydrogen gas. Six hydrogen sulfide evolutions were observed from Ledo coal, which were assigned to specific sulfur functional groups based on the TPR results from model compounds. These included mercaptan/disulfide, thiol, aromatic thioether, thiophene, pyrite, and complex thiophene groups. Additional experiments estimated the thioketonic sulfur content in Ledo coal to be 1.59%. Infrared spectroscopy was also used
Madkour-1986-Journal_of_Chemical_Technology_and_BiotechnologyAl Baha University
This document summarizes a theoretical study on the sulphate roasting of Umm-Gheig carbonate ore from Egypt to make it suitable for zinc electrowinning. Thermodynamic calculations were performed to determine the optimum conditions for sulphate roasting, including air ratio, temperature, and oxygen enrichment. Experimental roasting of the ore at temperatures up to 650°C produced a calcine that was 91.2% soluble zinc after leaching. The results indicated that sulphate roasting is a viable process for extracting zinc from this carbonate ore.
Madkour 1986-journal of-chemical_technology_and_biotechnologyAl Baha University
Thermodynamic Studies on Sulphate Roasting for Zinc Electrowinning from Carbonate Ore
The bulk of the work consists of a theoretical study of the possibility of submitting Umm-Gheig carbonate ore to sulphate roasting. The use of the admixture with pyrites is to enable a carbonate ore to be treated in a similar way to a sulphide ore, and by doing so, to produce a roasted product capable of being treated by orthodox zinc electrowinning methods using sulphate solutions. Thermodynamic studies have been made to find the optimum conditions for sulphate roasting, in either normal air or enriched 36% oxygen air. The results obtained from the experimental work at different roasting temperatures in a tube furnace indicated that a maximum dissolu- tion of 91.2% Zn with a 17.9% Fe could be obtained at a roasting temperature of 650°C for 4 h, followed by leaching in 4% H2S04 (by vol.) at 60°C. The results of the electron microscopic investigation confirmed by metal value data given in the ASTM cards coincide well with results given by chemical analysis
1. Lanthanide triflates are Lewis acid catalysts that are stable in water, allowing reactions to be carried out in aqueous solvents.
2. They are synthesized by reacting lanthanide oxides with aqueous triflic acid to form hydrated lanthanide triflates.
3. As water-tolerant Lewis acids, lanthanide triflates have been used to catalyze various carbon-carbon and carbon-heteroatom bond forming reactions like Friedel-Crafts alkylations, Mukaiyama aldol additions, and hydroxymethylation reactions.
Effect of vanadium on the behaviour of unsulfated and sulfated WTi-pillared c...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Effects of heat treatment on the catalytic activity and methanol tolerance of...sunidevi
This document summarizes a study on the effects of heat treatment on the catalytic activity and methanol tolerance of carbon-supported platinum alloys. Carbon-supported platinum (Pt/C) and platinum alloy (Pt-Co/C, Pt-Cu/C, Pt-Fe/C, Pt-Ni/C) catalysts were subjected to heat treatments at different temperatures. X-ray diffraction, transmission electron microscopy, and electrochemical measurements were used to characterize the catalysts and evaluate their oxygen reduction reaction activity and methanol tolerance. The results showed that heat treatment improved catalytic activity by increasing particle size but the optimal temperature depended on the catalyst. Pt-Cu/C treated at 350°C showed the highest activity and
Effect of alumina support on the performance ofNan Wu
This document describes a study that investigated the effect of different alumina supports on the performance of Pt-Sn-K/γ-Al2O3 catalysts in isobutane dehydrogenation. Alumina supports were synthesized by hydrochloric acid reflux and ammonia precipitation methods. Pt-Sn-K/γ-Al2O3 catalysts were prepared using these different alumina supports. Testing found that the catalyst supported on alumina from ammonia precipitation had smaller Pt particle sizes, weaker acidity, higher activity, and better selectivity and stability for isobutene production compared to the catalyst supported on alumina from hydrochloric acid reflux.
Effect of Solvent Swelling on the reactivity of demineralized Turkish LigniteIJERA Editor
In this research, effect of demineralization and solvent swelling on pyrolysis kinetics was investigated. The experiments were carried out to investigate theeffects of solvent swelling with different solvents, such as THF, Pyridine and DMSO after demineralization with HCl, HNO3 and HF successively. To calculate the activation energies of lignite sample during pyrolysis, TGA analyses were performed with raw and swollen samples at 5, 10 and 20° C/min heating rates. Coast-Redfernmodel was used for the determination of kinetic parameters. According to the results, the macromolecular structure of lignite was affected from these hydrogen bonding solvents. So, the activation energies of swollen samples found to be less than the raw lignite sample for all heating rates. The reactivity of lignite samples can be ordered as follows; DMSO swollen sample > Pyridine swollen sample> THF swollen sample. Activation energy of DMSO swollen lignite sample is 10.62 kJ/mole whereas activation energies of pyridine swollen and THF swollen sample are 17.83, 25.76 kJ/mol, respectively at a heating rate of 10° C/min. The results indicated that, solvent swelling has catalytic effect on pyrolysis kinetics.
This document summarizes research on using iron-based catalysts containing a second metal like magnesium or molybdenum for direct coal liquefaction. The key points are:
1) Iron-based catalysts containing magnesium or molybdenum as a second metal were tested for direct coal liquefaction.
2) Molybdenum increased catalyst activity the most, resulting in over 90% coal conversion at 400°C. Oil yields also increased significantly with molybdenum.
3) Tetralin and phenanthrene were used as solvents, with catalytic effects being more evident using phenanthrene as it is a poorer hydrogen donor.
This document presents an electrochemical and computational study of oxygen reduction reaction (ORR) on nonprecious transition metal/nitrogen doped carbon nanofiber catalysts. Electrochemical measurements showed that pyrolyzed Fe/N/C catalyst promotes a four-electron ORR pathway, while O2 reduction on Co/N/C occurs mainly via a two-electron pathway. Density functional theory calculations predicted that ORR could occur through a four-electron associative pathway on an FeN4 active site, but may terminate after two electrons on a CoN4 site due to high activation energy for O-O bond splitting. The results suggest that FeN4 and CoN4 clusters may be the main active sites for
The document provides an overview of catalysis. It defines a catalyst as a substance that speeds up a chemical reaction but is not consumed by the reaction. It discusses different types of catalysis including homogeneous catalysis where the catalyst is in the same phase as the reactants, and heterogeneous catalysis where the catalyst is in a different phase. The document also covers catalyst characterization techniques, factors that can lead to catalyst deactivation, and methods for catalyst regeneration. Examples are provided throughout to illustrate catalysis concepts and applications.
Platinum promotion increases the rate of Fischer-Tropsch synthesis over cobalt-based catalysts. Temperature programmed reduction experiments showed that a platinum-promoted cobalt catalyst reduced to a higher degree than an unpromoted cobalt catalyst, indicating that platinum facilitates the reduction of cobalt oxide via a proposed hydrogen spillover mechanism. During Fischer-Tropsch testing, a hybrid catalyst containing physically separated platinum and cobalt particles performed similarly to a co-impregnated platinum-cobalt catalyst, providing limited evidence for hydrogen spillover. Platinum did not affect product selectivity. Further experiments are needed to better understand the role of platinum during cobalt oxide reduction and the Fischer-Tropsch reaction.
This document summarizes a study investigating ultra-deep adsorptive desulfurization of diesel fuel over supported TiO2−CeO2 adsorbents. Key findings include:
1) Light irradiation of diesel fuel prior to adsorption treatment resulted in a 30-fold increase in desulfurization capacity compared to untreated fuel, achieving sulfur removal to below 1 ppmw.
2) Sulfur K-edge XANES analysis identified sulfones as the primary sulfur species on spent adsorbents, suggesting light irradiation chemically transforms original sulfur compounds.
3) Adsorption selectivity tests showed higher removal of indole and sulfones compared to thiophenes and poly
Effects of heat treatment on the catalytic activity and methanol tolerance of...tshankar20134
This document studies the effects of heat treatment on the catalytic activity and methanol tolerance of carbon-supported platinum alloys. Platinum (Pt), platinum-cobalt (Pt-Co), platinum-copper (Pt-Cu), platinum-iron (Pt-Fe), and platinum-nickel (Pt-Ni) catalysts were heat treated at different temperatures and their properties were analyzed. Heat treatment was found to increase particle size but also improved catalytic activity in most cases. The optimum heat treatment temperature depended on the specific catalyst. Pt-Cu/C and Pt-Fe/C catalysts heat treated at 350°C showed the highest oxygen reduction reaction activity and best methanol tolerance. Overall, Pt-
A STUDY OF MOLYBDENUM CARBIDE CATALYST FOR FISCHER-TROPSCH SYNTHESIS-MEngSc P...Farhan Munir
This document is a thesis submitted by Farhan Munir for the degree of Master of Engineering Science in Process Engineering at the University of New South Wales in November 2001. The thesis studies molybdenum carbide catalyst for Fischer-Tropsch synthesis. It begins with acknowledgments and a table of contents. Chapter 1 provides an introduction on Fischer-Tropsch synthesis and motivation for studying Mo2C catalyst. Chapter 2 discusses Fischer-Tropsch synthesis background including reactions, thermodynamics, kinetics and mechanisms. Chapter 3 discusses Fischer-Tropsch catalysts including active metals, supports, and preparation methods. Chapter 4 focuses specifically on molybdenum carbide catalyst. The objectives, experimental details, results
This document investigates three pyrazolo-pyrimidine derivatives (APP, HPP, MPP) as corrosion inhibitors for copper in sulfuric acid solution. Electrochemical measurements, surface analysis techniques, and theoretical calculations were used. The results show that the inhibitors were effective at inhibiting copper corrosion, with inhibition efficiency increasing with concentration. XPS and molecular dynamics simulations helped explain the adsorption and inhibition mechanisms. HPP and MPP were found to be more effective inhibitors than APP.
Similar to Catalysis Today(1997) Sugioka Et.Al (20)
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/temporal-event-neural-networks-a-more-efficient-alternative-to-the-transformer-a-presentation-from-brainchip/
Chris Jones, Director of Product Management at BrainChip , presents the “Temporal Event Neural Networks: A More Efficient Alternative to the Transformer” tutorial at the May 2024 Embedded Vision Summit.
The expansion of AI services necessitates enhanced computational capabilities on edge devices. Temporal Event Neural Networks (TENNs), developed by BrainChip, represent a novel and highly efficient state-space network. TENNs demonstrate exceptional proficiency in handling multi-dimensional streaming data, facilitating advancements in object detection, action recognition, speech enhancement and language model/sequence generation. Through the utilization of polynomial-based continuous convolutions, TENNs streamline models, expedite training processes and significantly diminish memory requirements, achieving notable reductions of up to 50x in parameters and 5,000x in energy consumption compared to prevailing methodologies like transformers.
Integration with BrainChip’s Akida neuromorphic hardware IP further enhances TENNs’ capabilities, enabling the realization of highly capable, portable and passively cooled edge devices. This presentation delves into the technical innovations underlying TENNs, presents real-world benchmarks, and elucidates how this cutting-edge approach is positioned to revolutionize edge AI across diverse applications.
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as “keys”). In fact, it’s unlikely you’ll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
"NATO Hackathon Winner: AI-Powered Drug Search", Taras KlobaFwdays
This is a session that details how PostgreSQL's features and Azure AI Services can be effectively used to significantly enhance the search functionality in any application.
In this session, we'll share insights on how we used PostgreSQL to facilitate precise searches across multiple fields in our mobile application. The techniques include using LIKE and ILIKE operators and integrating a trigram-based search to handle potential misspellings, thereby increasing the search accuracy.
We'll also discuss how the azure_ai extension on PostgreSQL databases in Azure and Azure AI Services were utilized to create vectors from user input, a feature beneficial when users wish to find specific items based on text prompts. While our application's case study involves a drug search, the techniques and principles shared in this session can be adapted to improve search functionality in a wide range of applications. Join us to learn how PostgreSQL and Azure AI can be harnessed to enhance your application's search capability.
Discover top-tier mobile app development services, offering innovative solutions for iOS and Android. Enhance your business with custom, user-friendly mobile applications.
What is an RPA CoE? Session 2 – CoE RolesDianaGray10
In this session, we will review the players involved in the CoE and how each role impacts opportunities.
Topics covered:
• What roles are essential?
• What place in the automation journey does each role play?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
QA or the Highway - Component Testing: Bridging the gap between frontend appl...zjhamm304
These are the slides for the presentation, "Component Testing: Bridging the gap between frontend applications" that was presented at QA or the Highway 2024 in Columbus, OH by Zachary Hamm.
What is an RPA CoE? Session 1 – CoE VisionDianaGray10
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
• The role of a steering committee
• How do the organization’s priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
"Scaling RAG Applications to serve millions of users", Kevin GoedeckeFwdays
How we managed to grow and scale a RAG application from zero to thousands of users in 7 months. Lessons from technical challenges around managing high load for LLMs, RAGs and Vector databases.
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
inQuba Webinar Mastering Customer Journey Management with Dr Graham HillLizaNolte
HERE IS YOUR WEBINAR CONTENT! 'Mastering Customer Journey Management with Dr. Graham Hill'. We hope you find the webinar recording both insightful and enjoyable.
In this webinar, we explored essential aspects of Customer Journey Management and personalization. Here’s a summary of the key insights and topics discussed:
Key Takeaways:
Understanding the Customer Journey: Dr. Hill emphasized the importance of mapping and understanding the complete customer journey to identify touchpoints and opportunities for improvement.
Personalization Strategies: We discussed how to leverage data and insights to create personalized experiences that resonate with customers.
Technology Integration: Insights were shared on how inQuba’s advanced technology can streamline customer interactions and drive operational efficiency.
2. 62 M. Sugioka et al./ Catalysis Today 39 (1997) 61-67
under 1 atm by using a conventional fixed bed flow
reactor. Thiophene was introduced into the reactor by = . - - ~ PVFSM-16 •
passing hydrogen through a thiophene trap cooled at
0°C. The reaction products were analyzed by a gas- '2 ..................................._..~...~q._..~?./~
chromatograph.
l SO • Pd/FSM~I6 •
FSM-16-supported noble metal catalysts were pre- 40
pared by an impregnation method using noble metal 30 " - P~SH-16
chloride aqueous solutions; the amount of metal load-
10 Ir/FSM-~ 6
ing was 5 wt%. All catalysts were calcined at 500°C 0
for 4 h in air and were reduced at 450°C for 1 h prior to 0 1 2 3 4 5
Time on stream[hr]
the reaction. Presulfiding treatment of the catalysts
W/F-37,90. hr/mol Hz/TIliophene=30
was performed by 5% H2S-H2 mixture at 400°C for
1 h. XRD analysis of the catalysts was carried out by Fig. 1. Hydrodesulfurization thiopheneover noble metal/FSM-
of
using Rigaku diffractometer with Cu K~t radiation. 16 catalystsat 350°C.
We used mesoporous silicate FSM-16 (surface area
970 m2/g, channel diameter 27 ,~) which was provided
by Toyota Central R&D Labs., Japan.
time and Pd/FSM-16 and Rh/FSM-16 catalysts
showed lower steady state activity than CoMo/
3. Results and discussion A1203 catalyst. Among noble metal/FSM-16 catalysts,
Pt/FSM-16 showed the highest activity for the hydro-
3.1. Catalytic activities o f noble metals supported desulfurization of thiophene and the activity of Pt/
on FSM-16 FSM-16 catalyst was higher than that of CoMo/A1203
catalyst. Pt/FSM-16 catalyst also showed higher activ-
The catalytic activities of transition metals sup- ity than that of Pt supported on silica gel (SiO2) in the
ported on FSM-16 were examined at 350°C for the hydrodesulfurization of thiophene. The high and
hydrodesulfurization of thiophene. It was found that stable activity of Pt/FSM-16 catalyst in the hydrode-
the catalytic activities of transition metals/FSM-16 sulfurization of thiophene was kept even after it had
such as Ni/FSM-16, Co/FSM-16, Fe/FSM-16, W/ reacted for 20 h.
FSM-16, Mo/FSM-16 (5wt% loading), 15wt% Table 1 summarizes the activities of various cata-
MoO3/FSM-16, 5 wt% NiO-15 wt% MoO3/FSM-16 lysts used in this work.
and 5 wt% COO-15 wt% MoO3/FSM-16 showed low As PffFSM-16 showed the highest catalytic activity
activity and their activity values were lower than that in the hydrodesulfurization of thiophene at 350°C, we
of commercial CoMo/A1203 catalyst. Then we exam- studied in detail the catalyst performance and the
ined the catalytic activities of noble metals supported reaction mechanism in the hydrodesulfurization of
on FSM-16. Fig. 1 shows the hydrodesulfurization of thiophene over Pt/FSM-16 catalyst. It was found that
thiophene over various noble metal/FSM-16 catalysts the catalytic activity of Pt/FSM-16 was decreased
at 350°C. It was found that the catalytic activities of slightly by the presulfiding with H2S-H2 mixture as
noble metal/FSM-16 varied remarkably with the kind shown in Table 1. Thus, we used the Pt/FSM-16
of noble metals. The order of the activities of these catalyst without presulfiding.
catalysts for the hydrodesulfurization of thiophene In the hydrodesulfurization of thiophene over Pt/
after 2 h reaction was as follows: Pt/FSM-16>Pd/ FSM-16 catalyst, main reaction products were C4
FSM-16>Rh/FSM-16>>Ru/FSM-16, Ir/FSM-16, Au/ hydrocarbons (butane 88%, butenes 12%); trace
FSM-16. amount of C1-C3 hydrocarbons was also formed.
The initial activities of Pt/FSM-16, Pd/FSM-16 and These results indicate that Pt/FSM-16 catalyst has
Rh/FSM-16 were higher than that of commercial high hydrogenating ability for unsaturated Ca hydro-
CoMo/A1203 catalyst (dotted line). However, the carbons and low hydrocracking activity for hydrocar-
activities of these catalysts decreased with the reaction bons in the presence of hydrogen sulfide.
3. M. Sugioka et al./Catalysis Today 39 (1997) 61~7 63
Table 1 that of C o M o / A 1 2 0 3 catalyst for the reaction tempera-
Catalytic activities of various metals supported on FSM-16 in the ture above 320°C. The low activity of Pt/FSM-16
hydrodesulfurization of thiophene at 350°C (W/F-37.9 g h/mol,
H2/Thiophene=30)
catalyst below 320°C might be attributed to the sig-
nificant resistance of reactant diffusion into the chan-
Catalyst Conversion ( % ) a nel of FSM-16. That is to say, the comparable size of
Reduced Sulfided Pt particles to the p o r e d i a m e t e r o f F S M - 1 6 w o u l d b e
Catalystb Catalystc f o r m e d in the c h a n n e l o f F S M - 16 after the r e d u c t i o n o f
5 wt% Ni/FSM-16 2 Trace P t / F S M - 1 6 b y h y d r o g e n [14] a n d Pt p a r t i c l e s f o r m e d
5 wt% Co/FSM-16 2 9 i n h i b i t the d i f f u s i o n o f t h i o p h e n e into the c h a n n e l o f
5 wt% Fe/FSM-16 Trace Trace F S M - 1 6 at the r e a c t i o n t e m p e r a t u r e b e l o w 320°C.
5 wt% W/FSM-16 Trace 1
5 wt% Mo/FSM-16 15 19
15 wt% MoO3/FSM-16 39 22 3.2. Improvement of catalytic activity of Pt/FSM-16
5 wt% NiO-15 wt% MoO3/FSM-16 22 35
5 wt% COO-15 wt% MoOa/FSM-16 30 32 Results showed that 5 wt% Pt/FSM-16 calcined at
5 wt% Ru/FSM- 16 1 Trace 500°C had the highest catalytic activity for the hydro-
5 wt% Au/FSM-16 1 Trace desulfurization of thiophene. However, it is uncertain
5 wt% Ir/FSM-16 9 9 whether these preparation conditions are optimal or
5 wt% Rh/FSM-16 32 31 not. Therefore, we examined the effect of preparation
5 wt% Pd/FSM-16 56 62
5 wt% Pt/FSM-16 90 82 conditions on the catalytic activity of Pt/FSM-16 in
order to obtain the optimal activity of Pt/FSM-16
5 wt% Pt/SiO2 (JRC-SIO-1) 51 --
catalyst for the hydrodesulfurization of thiophene.
Commercial CoMo/A1203 -- 60
Fig. 3 shows the effect of Pt loading on the activity
aReaction after 2 h. of Pt/FSM-16 catalyst. The catalytic activity increased
bCatalysts were reduced at 450°C for 1 h °
with the increase of Pt loadings up to about 3.5 wt%
CCatalysts were sulfided at 400°C for 1 h after reduced at 450°C.
and the activity became constant for loading above
3.5 wt%. Thus, it can be concluded that 5 wt% loading
of Pt on Pt/FSM-16 is enough for obtaining the
100
maximum activity.
,o
Pt/FSM-16
~'~
"~ 50
Go
80
70
/ / ' l ~ l / f i '•~ " """"~"
coMo~
"
" "~
100
90
~ 40
80
30
70
60
10
8
5o
0 , , i i i i
200 220 240 260 280 300 320 340 360 380 400
Reaction temperature['C]
3O
Fig. 2. Comparison of catalytic activity of Pt/FSM-16 with that of 20
commercial CoMo/A1203 catalyst in the hydrodesulfurization of
10
thiophene.
1 2 3 4 5 6
Fig. 2 shows the comparison of the activity of FSM- Pt loading[w1%]
16 catalyst with CoMo/Al203 catalyst. It was found Fig. 3. Relationship between Pt loading and the catalytic activity
that the catalytic activity of Pt/FSM-16 is higher than of Pt/FSM-16 in the hydrodesulfurization of thiophene at 350°C.
4. 64 M. Sugioka et al./ Catalysis Today 39 (1997) 61-67
lOO lOO
90
80
80
70
70
Z 6o
9[ 6o
i'
ii
•~ 50
3O
20
I~-Ir Pt-Pd P~-Rh PI-Ru 25'~1%PI,FSM-165wI%Pt/FSM-16
10
0 i , t i Fig. 5. Catalytic activity of Pt (2.5 wt%) combined with other
200 300 400 500 600 700 800 noble metals (2.5 wt%) supported on FSM-16 in the hydrodesul-
Calcination temperature ['C] furization at 350°C.
Fig. 4. Effect of calcination temperature of Pt/FSM-16 on the
catalytic activity in the hydrodesulfurization of thiophene at 350°C.
to learn more about the origin of high and stable
activity of Pt/FSM-16 catalyst. The introduction of
hydrogen sulfide (3 ml/min) was performed using a
Fig. 4 shows the effect of calcination temperature microfeeder with a glass syringe; the concentration of
on the catalytic activity of Pt/FSM-16. The catalytic hydrogen sulfide in the hydrogen stream was ca.
activity of Pt/FSM-16 increased slightly up to the 5 vol%. The catalytic activity of Pt/FSM-16 was
calcination temperature at 500°C and it decreased remarkably decreased by the introduction of hydrogen
above 500°C. It was found that the calcination of sulfide in the course of hydrodesulfurization reaction.
the catalyst at 500°C is the optimal condition. However, the decreased activity was almost restored
In the previous paper [10], we showed that the after cutting off the introduction of hydrogen sulfide as
steady state activity of Pt/USY catalyst in the hydro- shown in Fig. 6. This shows that hydrogen sulfide is
desulfurization of thiophene was remarkably reversibly adsorbed on Pt/FSM-16.
improved by the combination with other noble metals. Furthermore, the activity of Pt/FSM-16 catalysts
Combination of Pt with Pd was the most effective. was slightly decreased after the presulfiding with 5%
Thus, we tried to enhance the steady state activity of H2S-H2 mixture at 400°C as shown in Fig. 6. These
Pt/FSM-16 by combining Pt (2.5 wt%) with other results indicate that the Pt/FSM-16 catalyst has high
noble metals (2.5 wt%). It was found that the steady
state activity of Pt/FSM-16 was not improved by the
combination of Pt with other noble metals and the
activity of 2.5 wt% Pt/FSM-16 was decreased by the 1oo
90
addition of 2.5 wt% other noble metals except Pd as
80
shown in Fig. 5.
70
3.3. Properties of Pt/FSM-16 catalyst 5O
agt,i ~ )
4O
Pt/FSM-16 catalyst showed high and stable activity 3O
for the hydrodesulfurization of thiophene among the 2O
10
noble metals supported on FSM-16. We also studied in
0
more detail concerning the catalytic properties of Pt/ 2 3 6
Time on stream [hr]
FSM-16 in the hydrodesulfurization of thiophene.
The effect of introduction of hydrogen sulfide on the Fig. 6. Reversible inhibition of hydrogen sulfide in the hydro-
catalytic activity of Pt/FSM-16 was examined in order desulfurization of thiophene at 350°C.
5. M. Sugioka et al./Catalysis Today39 (1997) 61-67 65
sulfur tolerant properties for the hydrodesulfurization
of thiophene as well as Pt/HZSM-5 catalyst described
in the previous paper [9].
On the other hand, as mentioned in the previous
papers [7-9], the acid site, especially Br~nsted acid
site, of H-zeolites (HY, USY, HZSM-5) as support in
5wt~/FSM-16
noble metal/H-zeolite catalysts plays an important
role for the hydrodesulfurization of thiophene. In this
5wt~Pt/FSM-~6
study, we examined the effect of introduction of
ammonia on the catalytic activity of Pt/FSM-16 in FS~I 6
the hydrodesulfurization of thiophene in order to ,0 20 30 ,'0 5'o ,; ,; 8; --
clarify the role of acidic properties of Pt/FSM-16 in Ze/degree
the hydrodesulfurization of thiophene. The introduc- Fig. 8. XRD patterns for various noble metal/FSM-16 catalysts
tion of ammonia (3 ml/min) was carried out using before reduction.
microfeeder with glass syringe as well as the intro-
duction of hydrogen sulfide. It was revealed that the
catalytic activity of Pt/FSM-16 was decreased by the 3.4. XRD analysis of Pt/FSM-16 catalyst
introduction of ammonia (ca. 5 vol%) in the course of
hydrodesulfurization reaction and decreased activity Fig. 8 shows the XRD patterns of FSM-16 and
was completely regenerated after cutting off the intro- noble metal/FSM-16 before reduction. Almost the
duction of ammonia as shown in Fig. 7. The catalytic same XRD patterns as that of FSM-16 were obtained
activity of PffFSM-16 was remarkably decreased by before and after loading of noble metals. This indi-
the addition of small amount (1 wt%) of sodium using cates that the structure of FSM-16 was maintained
sodium hydroxide aqueous solution to Pt/FSM-16 after loading of noble metals on FSM-16. No peaks
catalyst. Furthermore, FSM-16 also showed the cata- of Rh were observed on Rh/FSM-16 catalyst. On
lytic activities for the isomerization of 1-butene the other hand, broad and sharp peaks of Pd and Pt
(25 °C) and cyclopropane (150°C) and the dehydration were observed in the XRD analysis of Pd/FSM-16
of 2-propanol (250°C), which are typical acid-cata- and Pt/FSM-16 catalysts. The same XRD pattern
lyzed reactions. These results indicate that the acid of Pt/FSM-16 was observed for PtJFSM-16 after
sites exist on Pt/FSM-16 catalysts and the acid sites reduction at 450°C. These results infer that Rh is
play an important role for the hydrodesulfurization of loaded on FSM-16 with high dispersion but Pd
thiophene over Pt/FSM-16 catalyst. and Pt are loaded on FSM-16 with relatively large
particle size. The order of the dispersion of noble
metals on FSM-16 is assumed to be Rh/FSM-16>Pd/
FSM-16>Pt/FSM-16. This order is reverse to that
IO0 of the steady state activity of noble metal/FSM-16
90
catalysts in the hydrodesulfurization of thiophene. It is
80
interesting that the lower dispersion of noble metals
7O
.~ 60
on FSM-16, especially Pt/FSM-16, showed higher
Nm
~ 5O
int~ i catalytic activity for the hydrodesulfurization of
40 thiophene.
30
20
3.5. Mechanism of hydrodesulfurization of
10
thiophene on Pt/FSM-16 catalyst
0
3
qqmeoll stream [hr]
Pt/FSM-16 showed higher catalytic activity than
Fig. 7. Effect of introduction of ammoniaon the catalytic activity commercial CoMo/A1203 catalyst in the hydro-
of Pt/FSM-16 in the hydrodesulfurizatrionof thiophene at 350°C. desulfurization of thiophene. We also studied the
6. 66 M. Sugioka et al.ICatalysis Today 39 (1997) 61-67
mechanism of hydrodesulfurization of thiophene H2
over Pt/FSM-16 catalyst. As mentioned above, the HzS + C4 H y d r o c a r b o n ~ ' ~ /
acid site of FSM-16 in Pt/FSM-16 catalyst plays
an important role for the hydrodesulfurization of
thiophene. That is, it is assumed that the acid site
of FSM-16 in the Pt/FSM-16 catalyst acts as active
sites for the activation of thiophene, whereas Pt
IT Spillover
particles on FSM-16 act as active sites for the activa-
tion of hydrogen in the hydrodesulfurization of
thiophene. Furthermore, we supposed the existence
of spillover hydrogen in the hydrodesulfurization of Scheme 1. The possible mechanism of thiophenehydrodesulfur-
ization over Pt/FSM-16catalyst.
thiophene over Pt/FSM-16 catalyst. Hence, we tried to
confirm the existence of spillover hydrogen in the
hydrodesulfurization of thiophene. The catalytic mesoporous zeolite-based hydrodesulfurization cata-
activity of Pt/SiO2 (quartz) mixed mechanically lyst for petroleum feedstocks.
with FSM-16 was examined. It was found that the
activity of mixed catalyst obtained experimentally was
higher than that of the calculated one (A+B) as shown 4. Conclusion
in Fig. 9.
This suggests that there exists spillover hydrogen on It was found that the Pt/FSM-16 catalyst showed
Pt/FSM-16 in the hydrodesulfurization of thiophene. high and stable activity for the hydrodesulfurization of
Therefore, we propose a possible mechanism for the thiophene, Therefore, it is concluded that Pt/FSM-16
hydrodesulfurization of thiophene over Pt/FSM-16 might be a promising new hydrodesulfurization cata-
catalyst as shown in Scheme 1. In the proposed lyst for the petroleum feedstocks.
mechanism, thiophene is activated on the acid site
of FSM-16 and hydrogen is activated on Pt to form
spillover hydrogen. The spillover hydrogen formed on Acknowledgements
Pt particle attacks the activated thiophene formed on
the acid site on FSM-16. This work was partly supported by a grant-in-aid
On the basis of the proposed mechanism, it would from Ministry of Education, Science and Culture,
be possible to develop much more highly active Japan (082322060, 09650854) and the Petroleum
Energy Center of Japan. The authors thank Toyota
Central R&D Labs., Japan, for kind provision of FSM-
16 and also thank Dr. Yoshiaki Fukushima and Mr.
Shinji Inagaki of Toyota Central R&D Labs., Japan,
35
(A) {0.1g) + S ~ (B) (0.1g) for their valuable comments.
30
Z5
References
15
10 [1] S. Gobolos,M. Breysse,M. Cattenot,T. Decamp,M. Lacroix,
S
J.L. Portefaix,M.L. Vrinat, Stud. Surf. Sci. Catal. 50 (1989)
FSM-16(A) (0.1g) 243.
0 [2] R. Cid, J.L.G. Fierro,A.L. Agudo, Zeolites 10 (1991)95.
20 40 60 80 100 120
Tm~onlueam[min]
[3] M. Laniecki,W. Zmierczak,Zeolites 11 (1991)95.
[4] M. Sugioka,J. Japan Petrol. Inst. 33 (1990)280.
Fig. 9. Hydrodesulfurizationof thiophene over FSM-16 (A), Pt/ [5] M. Sugioka, Y. Takase, K. Takahashi, Proceedings of
quartz (B), and mechanicallymixed(FSM-16(A)+Pt/quartz(B)) at JECAT'91, 1991,p. 224.
350°C. [6] M. Sugioka,Zeoraito(Zeolite) 10 (1993) 121.
7. M. Sugioka et al./Catalysis Today 39 (1997) 61~57 67
[7] M. Sugioka, Erdol and Kohle, Erdgas Petrochemie 48 (1995) Kreage, K.D. Smitt, T.-W. Chu, D.H. Olson, E.W. Sheppard,
128. S.B. McCulleni, J.B. Higgions, J.L. Schlenker, J. Am. Chem.
[8] M. Sugioka, C. Tochiyama, E Sado, N. Maesaki, Stud. Surf. Soc. 114 (1992) 10834.
Sci. Catal. 100 (1996) 441. [12] T. Yanagisawa, T. Shimizu, K. Kuroda, C. Kato, Bull. Chem.
[9] M. Sugioka, C. Tochiyama, Y. Matsumoto, E Sado, Stud. Soc. Jpn. 62 (1990) 763.
Surf. Sci. Catal. 94 (1995) 544. [13] S. Inagaki, Y. Fukushima, K. Kuroda, J. Chem. Soc., Chem.
[10] M. Sugioka, E Sado, Y. Matsumoto, N. Maesaki, Catal. Comm. (1993) 680.
Today 29 (1996) 255. [14] S. Inagaki, K. Fukumoto, Y. Fukushima, Shokubai (Catalyst)
[11] J.S. Beck, J.C. Vartuli, W.J. Roth, M.E. Leonowicz, C.T. 37 (1995) 191.