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,
Use of conventional sources of energy to generate electricity is
increasing rapidly due to growing energy demands in every sector which is the major cause for pollution as well and also is an environmental concern for future. Considering this, there is lot of R&D going on in the field of alternate energy sources with recent advancements in technology. One of the recent advancement is the perovskite solar technology in the photovoltaics industry. The power conversion efficiency of perovskite solar cells has been improved from 9.7 to 20.1% within 4 years which is the fastest advancement ever in the photovoltaic industry. Such a high photovoltaic performance can be attributed to optically high absorption characteristics of the hybrid lead perovskite materials.
In this review, different perovskite materials are discussed along with the fundamental details of the hybrid lead halide perovskite materials. The fabrication techniques, stability, device structure and the chemistry of the perovskite structure are also described aiming for a better understanding of these materials and thus highly efficient perovskite solar cell devices. In addition some advantages and drawbacks are also discussed here to outline the prospects and challenges of using the perovskites in commercial PV devices.
Synthesis and charaterization of la1 x srxmno3 perovskite nanoparticlesMai Trần
In recent times perovskite materials are extensively studied and have attracted much attention because they exhibit interesting the properties, showing potential applications in commercial, technical and biomedical. In Vietnam, perovskite materials be of interest research and applications are strong but with major research direction is to go deep into the electrical properties and the magnetic properties. The Lanthanum Strontium manganite is a perovskite-based crystal-structured ceramic material with the formula of La1-xSrxMnO3, where x describes the doping ratio. It has attracted much attention due to its good magnetic, electrical, and catalytic properties and is becoming an attractive possibility material in several biomedical applications, particularly with nano-size. In industry, this material is commonly used in as a cathode material in commercially produced solid oxide fuel cells. In this thesis, we present the Perovskite nanoparticles La1-xSrxMnO3 were successfully synthesized of the nanosize La1-xSrxMnO3 at x = 0; 0.1; 0.2; 0.3 and 0.4 which prepared by a modified sol-gel method. Structure and magnetic properties of them were systematically investigated in dependence on doped Sr ratio x. The structure was investigated by XRD and show slightly changed but magnetic properties varied strongly with changing the doping ratio x. Magnetic properties of samples were studied by Vibrating Sample Mode of Physical Properties Measurement System show at the room temperature, the samples show superparamagnetic properties with high saturated magnetization MS of 57 emu/g which strongly dependents on the doped Sr ratio x.
Synthesis and Characterisation of Copper Oxide nanoparticlesIOSR Journals
Cupric oxide (CuO) nanoparticles were prepared by the chemical route by calcinations at a higher temperature from 300oC to 400 oC. For the comparison transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements were made through JCPDS. There is good agreement between data produced by spectroscopy and the microscopic measurements.
Perovskite: introduction, classification, structure of perovskite, method to synthesis, characterization by XRD and UV- vis spectroscopy , lambert beer's law, material properties and advantage and application.
Use of conventional sources of energy to generate electricity is
increasing rapidly due to growing energy demands in every sector which is the major cause for pollution as well and also is an environmental concern for future. Considering this, there is lot of R&D going on in the field of alternate energy sources with recent advancements in technology. One of the recent advancement is the perovskite solar technology in the photovoltaics industry. The power conversion efficiency of perovskite solar cells has been improved from 9.7 to 20.1% within 4 years which is the fastest advancement ever in the photovoltaic industry. Such a high photovoltaic performance can be attributed to optically high absorption characteristics of the hybrid lead perovskite materials.
In this review, different perovskite materials are discussed along with the fundamental details of the hybrid lead halide perovskite materials. The fabrication techniques, stability, device structure and the chemistry of the perovskite structure are also described aiming for a better understanding of these materials and thus highly efficient perovskite solar cell devices. In addition some advantages and drawbacks are also discussed here to outline the prospects and challenges of using the perovskites in commercial PV devices.
Synthesis and charaterization of la1 x srxmno3 perovskite nanoparticlesMai Trần
In recent times perovskite materials are extensively studied and have attracted much attention because they exhibit interesting the properties, showing potential applications in commercial, technical and biomedical. In Vietnam, perovskite materials be of interest research and applications are strong but with major research direction is to go deep into the electrical properties and the magnetic properties. The Lanthanum Strontium manganite is a perovskite-based crystal-structured ceramic material with the formula of La1-xSrxMnO3, where x describes the doping ratio. It has attracted much attention due to its good magnetic, electrical, and catalytic properties and is becoming an attractive possibility material in several biomedical applications, particularly with nano-size. In industry, this material is commonly used in as a cathode material in commercially produced solid oxide fuel cells. In this thesis, we present the Perovskite nanoparticles La1-xSrxMnO3 were successfully synthesized of the nanosize La1-xSrxMnO3 at x = 0; 0.1; 0.2; 0.3 and 0.4 which prepared by a modified sol-gel method. Structure and magnetic properties of them were systematically investigated in dependence on doped Sr ratio x. The structure was investigated by XRD and show slightly changed but magnetic properties varied strongly with changing the doping ratio x. Magnetic properties of samples were studied by Vibrating Sample Mode of Physical Properties Measurement System show at the room temperature, the samples show superparamagnetic properties with high saturated magnetization MS of 57 emu/g which strongly dependents on the doped Sr ratio x.
Synthesis and Characterisation of Copper Oxide nanoparticlesIOSR Journals
Cupric oxide (CuO) nanoparticles were prepared by the chemical route by calcinations at a higher temperature from 300oC to 400 oC. For the comparison transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements were made through JCPDS. There is good agreement between data produced by spectroscopy and the microscopic measurements.
Perovskite: introduction, classification, structure of perovskite, method to synthesis, characterization by XRD and UV- vis spectroscopy , lambert beer's law, material properties and advantage and application.
An introduction of perovskite solar cellsalfachemistry
This article introduces the development, structure and work mechanism of perovskite solar cells. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Advantages and problems of perovskite solar cellalfachemistry
This article mainly introduces the advantages and problems of perovskite solar cell. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Synthesis, characterization and electrocatalytic activity of silver nanorods ...kutty79
This paper describes a simple method of synthesizing silver nanorods using the polyol process, where propylene glycol serves both as a reducing
agent and as a solvent in the presence of a capping reagent such as polyvinylpyrrolidone (PVP). The diameter and length of silver nanorods could be
controlled by changing the AgNO3/PVP ratio. The end-to-end assembly of the silver nanorods was found. The silver nanorods were characterized by
using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and absorption spectroscopy. The catalytic activity of a
glassy carbon electrode with Ag nanorods exhibits extraordinary electrocatalytic activities towards the electro-reduction of benzyl chloride.
Infrared Spectral and EPR Studies of Mn2+ Ions Doped K2O - CdO - B2O3 - SiO2 ...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Device simulation of perovskite solar cells with molybdenum disulfide as acti...journalBEEI
Organo-halide Perovskite Solar Cells (PSC) have been reported to achieve remarkably high power conversion efficiency (PCE). A thorough understanding of the role of each component in solar cells and their effect as a whole is still required for further improvement in PCE. In this paper, the effect of Molybdenum Disulfide (MoS2) in PSC with mesoporous structure configuration was analyzed using Solar Cell Capacitance Simulator (SCAPS). With the MoS2 layer which having two-fold function, acting as a protective layer, by preventing the formation of shunt contacts between perovskite and Au electrode, and as a hole transport material (HTM) from the perovskite to the Spiro-OMETAD. As simulated, PSC demonstrates a PCE, ŋ of 13.1%, along with stability compared to typical structure of PSC without MoS2 (Δ ŋ/ŋ=-9% vs. Δ ŋ/ŋ=-6%). The results pave the way towards the implementation of MoS2 as a material able to boost shelf life which very useful for new material choice and optimization of HTMs
Toluene and its industrial applicationsrita martin
Toluene aromatic hydrocarbon solvent is a solvent in paints, lacquers, thinners, glues, correction fluid, carbon nanotubes and nail polish remover used as an octane booster in gasoline fuels
Keynote presented at SDD (12th May 2015)
Somewhere in the heart of a development process, essential to the very being of a product's existence, are the people who write, consider and wrestle with code. What motivates and demotivates them? What are the intellectual challenges and rewards? What are the skills they have and need and cognitive biases and environment they work with and against?
This talk by the editor of 97 Things Every Programmer Should Know considers the act of programming and those who do it and want to get better at it, from the perspective of development process to craft, from architecture to code.
An introduction of perovskite solar cellsalfachemistry
This article introduces the development, structure and work mechanism of perovskite solar cells. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Advantages and problems of perovskite solar cellalfachemistry
This article mainly introduces the advantages and problems of perovskite solar cell. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Synthesis, characterization and electrocatalytic activity of silver nanorods ...kutty79
This paper describes a simple method of synthesizing silver nanorods using the polyol process, where propylene glycol serves both as a reducing
agent and as a solvent in the presence of a capping reagent such as polyvinylpyrrolidone (PVP). The diameter and length of silver nanorods could be
controlled by changing the AgNO3/PVP ratio. The end-to-end assembly of the silver nanorods was found. The silver nanorods were characterized by
using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and absorption spectroscopy. The catalytic activity of a
glassy carbon electrode with Ag nanorods exhibits extraordinary electrocatalytic activities towards the electro-reduction of benzyl chloride.
Infrared Spectral and EPR Studies of Mn2+ Ions Doped K2O - CdO - B2O3 - SiO2 ...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Device simulation of perovskite solar cells with molybdenum disulfide as acti...journalBEEI
Organo-halide Perovskite Solar Cells (PSC) have been reported to achieve remarkably high power conversion efficiency (PCE). A thorough understanding of the role of each component in solar cells and their effect as a whole is still required for further improvement in PCE. In this paper, the effect of Molybdenum Disulfide (MoS2) in PSC with mesoporous structure configuration was analyzed using Solar Cell Capacitance Simulator (SCAPS). With the MoS2 layer which having two-fold function, acting as a protective layer, by preventing the formation of shunt contacts between perovskite and Au electrode, and as a hole transport material (HTM) from the perovskite to the Spiro-OMETAD. As simulated, PSC demonstrates a PCE, ŋ of 13.1%, along with stability compared to typical structure of PSC without MoS2 (Δ ŋ/ŋ=-9% vs. Δ ŋ/ŋ=-6%). The results pave the way towards the implementation of MoS2 as a material able to boost shelf life which very useful for new material choice and optimization of HTMs
Toluene and its industrial applicationsrita martin
Toluene aromatic hydrocarbon solvent is a solvent in paints, lacquers, thinners, glues, correction fluid, carbon nanotubes and nail polish remover used as an octane booster in gasoline fuels
Keynote presented at SDD (12th May 2015)
Somewhere in the heart of a development process, essential to the very being of a product's existence, are the people who write, consider and wrestle with code. What motivates and demotivates them? What are the intellectual challenges and rewards? What are the skills they have and need and cognitive biases and environment they work with and against?
This talk by the editor of 97 Things Every Programmer Should Know considers the act of programming and those who do it and want to get better at it, from the perspective of development process to craft, from architecture to code.
WTF - Why the Future Is Up to Us - pptx versionTim O'Reilly
This is the talk I gave January 12, 2017 at the G20/OECD Conference on the Digital Future in Berlin. I talk about fitness landscapes as applied to technology and business, the role of unchecked financialization in the state of our politics and economy, and why technology really wants to create jobs, not destroy them. (There is a separate PDF version, but some readers said the notes were too fuzzy to read.)
What does the future look like? Is it a dark space where we’re suffering from varying degrees of techamphetamine or are we heading towards a Utopian fantasy of abundance and harmony?
Understanding that our basic human needs and wants barely change, we explore the future state of a range of topics; from our need for physical sustenance through to our age-long fascination of transcending the limitations of our biology.
Looking at the future from a human perspective, our potential for greatness is teetering on a fine line between darkness and hope. We’re banking on the latter.
PEGylated magnetic nanoparticles (PEG@Fe3O4) as cost effectivealternative for...Pawan Kumar
An efficient, cost effective and environmental friendly PEGylated magnetic nanoparticle catalyzed oxida-tive cyanation via CH activation of tertiary amines to corresponding -aminonitriles using hydrogenperoxide as oxidant and sodium cyanide as cyanide source is described. The synthesized nanocatalyst waseasily recovered with the help of external magnet and was successfully reused for several runs withoutany significant loss in catalytic activity.
PEGylated magnetic nanoparticles (PEG@Fe3O4) as cost effectivealternative for...Pawan Kumar
tAn efficient, cost effective and environmental friendly PEGylated magnetic nanoparticle catalyzed oxida-tive cyanation via CH activation of tertiary amines to corresponding -aminonitriles using hydrogenperoxide as oxidant and sodium cyanide as cyanide source is described. The synthesized nanocatalyst waseasily recovered with the help of external magnet and was successfully reused for several runs withoutany significant loss in catalytic activity.
Deactivation Modeling through Separable Kinetics of Coking On Ni/CZ Catalyst ...IOSR Journals
Abstract : Steam methane reforming (SMR) is a very significant technique to produce hydrogen from fossil fuels. In this particular work, nickel is used as the active metal and ceria-zirconia (CZ) bi-metallic oxide is used as the support. The foremost challenge to this process is sooting or coking over the catalyst surface and blocking the active sites. For the economic viability of the catalyst, it is very significant to make it coke deposition resistant. This is the reason that the kinetic modeling of the deactivation is very important. Therefore, this paper is aimed to model the deactivation and activity of the catalyst. A rate model of the deactivation process is also developed using separable kinetics. A comparison with commercial catalyst is also reported to show that the Ni/CZ catalyst is much more stable towards the coking. Keywords –Coking, Deactivation, Methane, Separable kinetics, Steam reforming.
Carbon-cuprous oxide composite nanoparticles
were chemically deposited on surface of thin glass tubes of spent
energy saving lamps for solar heat collection. Carbon was
obtained from fly ash of heavy oil incomplete combustion in
electric power stations. Impurities in the carbon were removed by
leaching with mineral acids. The mineral free-carbon was then
wet ground to have a submicron size. After filtration, it was
reacted with concentrated sulfuric/fuming nitric acid mixture on
cold for 3-4 days. Potassium chlorate was then added drop wise on
hot conditions to a carbon slurry followed by filtration.
Nanocarbon sample was mixed with 5% by weight PVA to help
adhesion to the glass surface. Carbon so deposited was doped with
copper nitrate solution. After dryness, the carbon/copper nitrate
film was dipped in hydrazine hydrate to form cuprous oxide -
carbon composite, It was then roasted at 380-400 °C A heat
collector testing assembly was constructed of 5 glass coils
connected in series with a total surface area of 1250 cm2
. Heat
collection was estimated by water flowing in the glass coils that
are coated with the carbon/copper film,. Parameters affecting the
solar collection efficiency such as time of exposure and mass flow
rate of the water were studied. Results revealed that the prepared
glass coil has proven successful energy collector for solar heat.
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
Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured M...IOSR Journals
CeO2–ZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards liquid-phase oxidation of benzene.
Synthesis, Characterization and Electrical Properties of Polyaniline Doped wi...IJERA Editor
The polyaniline were prepared by using different inorganic and organic acids via oxidative polymerization
method. The prepared samples were characterized by FTIR, the peaks are found to be at 507 cm˗1, 592 cm˗1, 798
cm˗1, 1138 cm˗1, 1244 cm˗1, 1302 cm˗1, 1471 cm˗1 and 1556 cm˗1. These predominant peaks may be
confirming the formation of polyaniline. The structural analysis was studied by employing XRD; found that
polyaniline is amorphous in nature. The SEM studies reveal that they are agglomerated, irregular and size of
these grain increases with increasing amount of polyaniline with different organic and inorganic acids. The dc
conductivity (dc) as a function of temperature (T) for polyaniline is studied in the temperature range from 30 to
1600C. At higher temperature it is found that conductivity increases because of hopping of polarons from one
localized states to another localized states. The ac conductivity of polyaniline was prepared by oxalic acid show
high conductivity at 106 Hz. This is due to the space charge polarization and electrode polarizations.
Octahedral rhenium K4[Re6S8(CN)6] and Cu(OH)2cluster modifiedTiO2for the phot...Pawan Kumar
tOctahedral hexacyano rhenium K4[Re6S8(CN)6] cluster complexes were grafted onto photoactive Cu(OH)2cluster modified TiO2{Cu(OH)2/TiO2} support. The rhenium and copper cluster modified TiO2photocata-lyst combines the advantages of heterogeneous catalyst (facile recovery, recycling ability of the catalyst)with the reactivity, selectivity of the soluble molecular catalyst. The synthesized heterogeneous cata-lyst was found to be highly efficient photoredox catalyst for the reduction of CO2under visible lightirradiation. Methanol was found to be the major liquid product with the formation of hydrogen as a byproduct as determined with GC-FID and GC-TCD, respectively. The methanol yield after 24 h irradiationwas found to be 149 mol/0.1 g cat. for Re-cluster@Cu(OH)2/TiO2photocatalyst that is much higher than35 mol/0.1 g cat. for Cu(OH)2/TiO2and 75 mol/0.1 g cat. for equimolar rhenium cluster in the presenceof triethanolamine (TEOA) as a sacrificial donor. The quantum yields (MeOH) of Re-cluster@Cu(OH)2/TiO2and Cu(OH)2/TiO2were found to be 0.018 and 0.004 mol einstein−1, respectively. These values are muchhigher than those reported for other heterogeneous catalysts for six electron transfer reaction
Nitrogen-doped graphene-supported copper complex: a novel photocatalyst for C...Pawan Kumar
A copper(II) complex grafted to nitrogen-doped graphene (GrN700–CuC) was synthesized and then
demonstrated as an efficient photocatalyst for CO2 reduction into methanol under visible light irradiation
using a DMF/water mixture. The chemical and microstructural features of GrN700–CuC nanosheets were
studied by FTIR, XPS, XRD and HRTEM analyses. Owing to its truly heterogeneous nature, GrN700–CuC
could be easily recovered after the photocatalytic reaction and showed efficient recyclability for
subsequent runs.
JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
Neuro-symbolic is not enough, we need neuro-*semantic*Frank van Harmelen
Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as “predictable inference”.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Empowering NextGen Mobility via Large Action Model Infrastructure (LAMI): pav...
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylene
1. Reac Kinet Mech Cat (2012) 105:469–481
DOI 10.1007/s11144-011-0383-3
V-Mn-MCM-41 catalyst for the vapor phase oxidation
of o-xylene
C. Mahendiran • T. Maiyalagan • P. Vijayan •
C. Suresh • K. Shanthi
Received: 4 May 2011 / Accepted: 1 October 2011 / Published online: 21 October 2011
Ó Akademiai Kiado, Budapest, Hungary 2011
´ ´
Abstract The role of V and Mn incorporated mesoporous molecular sieves was
investigated for the vapor phase oxidation of o-xylene. Mesoporous monometallic
V-MCM-41 (Si/V = 25, 50, 75 and 100), Mn-MCM-41 (Si/Mn = 50) and bime-
tallic V-Mn-MCM-41 (Si/(V ? Mn) = 100) molecular sieves were synthesized by
a direct hydrothermal (DHT) process and characterized by various techniques such
as X-ray diffraction, DRUV-Vis spectroscopy, EPR, and transmission electron
microscopy (TEM). From the DRUV-Vis and EPR spectral study, it was found that
most of the V species are present as vanadyl ions (VO2?) in the as-synthesized
catalysts and as highly dispersed V5? ions in tetrahedral coordination in the calcined
catalysts. The activity of the catalysts was measured and compared with each other
for the gas phase oxidation of o-xylene in the presence of atmospheric air as an
oxidant at 573 K. Among the various catalysts, V-MCM-41 with Si/V = 50
exhibited high activity towards production of phthalic anhydride under the exper-
imental condition. The correlation between the phthalic anhydride selectivity and
the physico-chemical characteristics of the catalyst was found. It is concluded that
V5? species present in the MCM-41 silica matrix are the active sites responsible for
the selective formation of phthalic anhydride during the vapor phase oxidation of
o-xylene.
C. Mahendiran (&)
Department of Chemistry, Anna University of Technology Tirunelveli,
University College of Engineering, Nagercoil Campus, Nagercoil 629004, India
e-mail: cmmagi@gmail.com
T. Maiyalagan
School of Chemical and Biomedical Engineering, Nanyang Technological University,
Singapore 639798, Singapore
P. Vijayan Á C. Suresh Á K. Shanthi
Department of Chemistry, Anna University, Chennai 25, India
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2. 470 C. Mahendiran et al.
Keywords V and Mn-MCM-41 Á Vapor phase Á Oxidation Á o-xylene Á
Phthalic anhydride
Introduction
Heterogeneous catalyzed gas phase oxidation plays a vital role in the chemical
industry. In fact, selective oxidation is the simplest functionalization method; in
particular, more than 60% of products synthesized by catalytic routes in the
chemical industry are obtained by oxidation reactions [1]. From the standpoint of
environmental friendliness, much attention has been paid to the development of
metal catalysts for the selective oxidation using molecular oxygen as an oxidant
[2–5]. The oxidative product pthalic anhydride is a commercially important and
versatile intermediate in organic chemistry. The primary use of phthalic anhydride
(PA) is as a chemical intermediate in the production of plastics from vinyl chloride.
Phthalate esters, which function as plasticizers, are derived from phthalic anhydride.
Phthalic anhydride has another major use in the production of polyester resins and
other minor uses in the production of alkyl resins used in paints and lacquers, certain
dyes (anthraquinone, phthalein, rhodamine, phthalocyanine, fluorescein, and
xanthene dyes), insect repellents, and urethane polyester polyols. It has also been
used as a rubber scorch inhibitor [6].
A method for converting naphthalene to phthalic anhydride using sulfuric acid as
the oxidizing agent in the presence of mercury salt as the catalysts was discovered
by E. Sapper, and was patented by the Badische Anilin and Soda Fabrik in 1896.
During the last decade of the nineteenth century, the growing demand for phthalic
anhydride for use in the preparation of xanthene and the indigoid dyes led to
research toward the discovery of cheaper processes for its manufacture [7]. In this
context, Dias et al. [8] found that V2O5 supported TiO2 as an efficient catalyst for
phthalic anhydride production. However, due to its poor mechanical strength of
V2O5/TiO2 and low surface area, attention has been focused on the development of
catalysts with high mechanical strength and high surface area. In this context,
mesoporous MCM-41 molecular sieves with high surface area and tunable pore size
came into existence [9]. The unique physical properties have made these materials
highly desirable for catalytic applications [10, 11]. Isomorphous substitution of
silicon with other elements is an excellent strategy in creating active sites and
anchoring sites for active molecules in the design of new heterogeneous catalyst.
Many metals, e.g., Al, Ti, Mn, Fe, B, Ni and V, have been incorporated into the
silica matrix of MCM-41 [12–15]. Molecular sieves containing redox active metals,
like Ti, V, Cr, Fe, or Co, are increasingly used as heterogeneous catalysts for the
selective oxidation of organic compounds. Among the metals, particularly
vanadium and manganese were found to have remarkable catalytic activity for
the selective oxidation of various organic molecules when incorporated into silicate
molecular sieve [16–21]. In this paper, the vapor phase oxidation of o-xylene to
phthalic anhydride over V-MCM-41, Mn-MCM-41 and V-Mn-MCM-41 catalysts
has been investigated and correlated with the structural, electronic and surface
results obtained.
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3. V-Mn-MCM-41 catalyst 471
Experimental
Synthesis of V-MCM-41
V-MCM-41 (Si/V = 50) was synthesized by hydrothermal method reported
elsewhere [21] using sodium metasilicate (CDH) as silica source, cetyl trimethyl
ammonium bromide (CTAB, OTTO Chemie) as the structure-directing agent with
the following molar gel composition SiO2:0.02 (VOS4ÁH2O):0.2 CTAB:0.89
H2SO4:160 H2O. In a typical synthesis, 21.32 g of sodium metasilicate and
0.63 g of vanadyl sulfate monohydrate were dissolved in 60 g of water. The
reaction mixture was stirred for 2 h. Meanwhile, CTAB (5.47 g) was dissolved in
20 g of water. Then, the resultant mixture of sodium metasilicate and vanadyl
sulfate monohydrate was added dropwise into the CTAB solution. The final mixture
was stirred for 1 h. The pH of the gel was adjusted to 10.5–11 using 2 M sulfuric
acid followed by stirring for 3 h. The obtained gel was placed into an autoclave and
heated to 413 K under static conditions for 12 h. The resultant precipitate was
filtered, washed with deionized water and dried in air at 375 K and then finally
calcined at 773 K for 1 h in N2 flow and for 12 h in CO2-free air flow. The catalysts
V-MCM-41 (Si/V = 25, 75,100), Mn-MCM-41 (Si/Mn = 50) and V-Mn-MCM-41
(Si/(V ? Mn) = 100) were also synthesized in a similar manner wherein only the
ratio of vanadyl sulfate monohydrate for vanadium source and manganese acetate
for manganese source was adjusted.
Characterization of the catalysts
Inductively coupled plasma (ICP) optical emission spectroscopy was used for the
determination of the metal content in each sample synthesized above. The
measurements were performed with a Perkin-Elmer OPTIMA 3000 and the sample
was dissolved in a mixture of HF and HNO3 before the measurements. XRD
analysis was performed on Rigaku Miniflex X-ray diffractometer. A germanium
solid state detector cooled in liquid nitrogen with Cu Ka radiation source was used.
The samples were scanned between 0.5° and 8.5° (2h) in steps of 0.02° with the
counting time of 5 s at each point. N2 adsorption studies were carried out to
examine the porous properties of each sample. The measurements were carried out
on a Belsorpmini II (BEL Japan. Inc) instrument. All the samples were pre-treated
in vacuum at 573 K for 12 h in flowing N2 at a flow rate of 60 mL/min. The surface
area and pore size were obtained from these isotherms using the conventional BET
and BJH equation. The coordination environment of vanadium and manganese
containing MCM-41 catalysts was examined by diffuse reflectance UV-vis
spectroscopy. The spectra were recorded between 200 and 800 nm on a Shimadzu
UV-vis spectrophotometer (Model 2450) using BaSO4 as the reference. Further-
more, the coordination environment of vanadium and manganese was confirmed by
EPR (Varian E112 spectrometer operating in the X-band 9.2 GHz frequency) at
room temperature. Transmission electron microscopy (TEM) images were obtained
by using a JEOL electron microscope with an acceleration voltage of 200 kV.
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4. 472 C. Mahendiran et al.
Experimental procedure for the oxidation of o-xylene
The oxidation of o-xylene was carried out in a fixed bed down flow quartz reactor at
atmospheric pressure in the temperature range of 473–623 K with air flow of
0.02 mol h-1. Prior to the reaction, the reactor packed with 0.3 g of the catalyst was
preheated in a tubular furnace equipped with a thermocouple. The reactant (o-
xylene) was fed into the reactor through a syringe infusion pump at a predetermined
flow rate. The product mixture was collected at the time interval of 1 h and analyzed
by a gas chromatograph (GC-17A, Shimadzu) equipped with a flame ionization
detector. The gaseous products were analyzed by a TCD detector using an SE-30
column. After every run, the catalyst was regenerated to remove the coke deposit,
by passing a stream of pure dry air at a temperature of 773 K for 6 h. The effect of
various parameters, viz., temperature, weight hourly space velocity and time on
stream was studied on the regenerated catalyst.
Results and discussion
XRD
The XRD patterns of calcined V-MCM-41 materials with an atomic ratio of
(Si/V = 100, 75, 50, and 25), Mn-MCM-41 (50), and V-Mn-MCM-41
(Si/(V ? Mn) = 100) recorded at low diffraction angles are shown in Fig. 1 and
its inset. A strong intense peak observed in the 2h range between 2 and 38 for all the
samples is due to the reflection from (100) plane of MCM-41. Apart from this, low
intensity peaks in the 2h range 3–5°, corresponding to the higher order reflections
Intensity (a.u.)
Intensity (a.u.)
a
b
1 3 5 7 9 11
2 (Deg.)
a
b
c
d
0 2 4 6 8 10
2 (Deg.)
Fig. 1 X-ray diffraction patterns of (a) V-MCM-41 (100), (b) V-MCM-41 (75), (c) V-MCM-41 (50) and
(d) V-MCM-41 (25) catalysts. Inset (a) Mn-MCM-41 (50), (b) V-Mn-MCM-41 (Si/(V ? Mn) = 100)
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5. V-Mn-MCM-41 catalyst 473
Table 1 Physico-chemical characteristics of the catalysts
Catalyst V Mn d- Unit cell Surface Pore Pore Wall
content content spacing parameter area diameter volume thickness
(wt%)a (wt%)a ˚
(A) ˚
a0 (A) (m2/g) ˚
(A) (cm3/g) ˚
(A)
V-MCM-41 (25) 1.14 – 40.01 46.20 814 28.10 0.76 18.10
V-MCM-41 (50) 0.58 – 39.60 45.73 893 28.40 0.79 17.33
V-MCM-41 (75) 0.38 – 39.50 45.61 976 28.60 0.81 17.00
V-MCM-41 0.24 – 39.30 45.38 1,013 28.70 0.82 16.68
(100)
V-Mn-MCM-41 0.57 0.86 41.30 47.69 863 28.48 0.80 19.21
Si/(V ? Mn)
= 100
Mn-MCM-41 – 0.88 40.75 47.06 904 27.75 0.81 19.31
(50)
a
Results obtained from ICP-AES analysis
such as (110) and (200) planes, were also observed, which confirms the mesoporous
nature of the samples. Higher angle XRD (not shown) does not show any peaks for
extra framework vanadium oxide. The unit cell parameter (a0) calculated using the
formula, a0 = 2d100/H3, and d spacing values obtained using the Bragg’s
˚
equation 2dsinh = nk, where k = 1.54 A for Cu Ka radiation are presented in
Table 1. Upon introduction of V into the MCM-41, a slight decrease in the unit cell
parameter value was observed. However, when the metal content was increased,
the intensity of the diffraction peaks decreased, indicating that it may be due to
structural irregularity of the mesopores at high metal content as reported in
literature [22].
Nitrogen adsorption–desorption isotherms
The adsorption–desorption isotherms of the catalysts V, Mn and V-Mn-MCM-41
are illustrated in Fig. 2. A typical type IV isotherm as defined by IUPAC for
mesoporous material was obtained. The adsorption isotherm exhibits a sharp
increase in the P/Po range from 0.2 to 0.3 which is obviously characteristic of
capillary condensation within mesopores [23]. The P/Po position of the inflection
points is clearly related to the diameter in the mesopore range, and the step
indicates the mesopore size distribution. N2 adsorbed volumes at P/Po = 0.3, for
Si/V = 100, 75, 50, 25, Si/Mn = 50 and Si/Mn ? V = 100 are 350, 330, 315, 295,
275 and 250. The BET surface area, pore volume, and pore diameter, as a function
of V, Mn and V-Mn content are shown in Table 1. The increase in the vanadium
content slightly decreased the surface area, pore volume as well as pore diameter.
From the results, the N2 adsorption studies clearly indicate the successful incor-
poration of V and Mn. When V and Mn are used together, partial amorphization is
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6. 474 C. Mahendiran et al.
Fig. 2 N2 adsorption–desorption isotherms of catalysts (a) V-MCM-41 (100), (b) V-MCM-41 (75),
(c) V-MCM-41 (50) and (d) V-MCM-41 (25) Inset (a) Mn-MCM-41 (50), (b) V-Mn-MCM-41 (Si/
(V ? Mn) = 100)
occurs. It may be due to metal oxides blocking the molecular sieves pore or partial
collapse of pore structure.
DR-UV-vis spectroscopy
The DRUV-Vis spectra of V-MCM-41 (Si/V ratio = 25, 50, 75 and 100) catalysts
showed the presence of two shoulder peaks at 260 and the other at 340 nm (Fig. 3a–
d). These correspond to the tetrahedral V5? ions inside the wall and the tetrahedral
V5? ions on the surface of the wall, respectively [24]. The intensity ratio of these
two peaks seems to be relatively high for a catalyst with high vanadium loading. It is
also evident from the spectra that as the ratio of Si/V increased, there is a
corresponding decrease in the intensity of the peaks due to decrease in the number
of vanadium ions. These bands were attributed to the low-energy charge transfer
transition between tetrahedral oxygen ligands and a central V5? ion [25, 26]. Such a
tetrahedral environment was typical for silica matrix V5? ions. A typical spectrum is
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7. V-Mn-MCM-41 catalyst 475
Absorbance (a.u)
a
b
c
d
e
180 280 380 480 580 680
Wavelength (nm)
Fig. 3 DR-UV-vis spectra of catalysts (a) V-MCM-41 (25), (b) V-MCM-41 (50), (c) V-MCM-41 (75),
(d) V-MCM-41 (100) and (e) spent V-MCM-41 (50)
recorded for the spent V-MCM-41 (50) catalyst (Fig. 3e). There are no absorption
bands and this indicates that V5? species are absent in spent catalyst.
EPR
The EPR spectra of the as-synthesized V-MCM-41 samples with varying values
of Si/V atomic ratio (25, 50, 75, and 100) were recorded at room temperature and
are shown in Fig. 4a–d. The source for the synthesis of vanadium containing
mesoporous materials was vanadyl sulfate (V4?, d1), and all the as-synthesized
V-MCM-41 exhibits its characteristic EPR signal. In comparison, the EPR spectra
of as-synthesized and spent V-MCM-41 (Si/V = 50) are also shown in Fig. 5a, b.
It is interesting to note the absence of the EPR signal in the spent catalyst (Fig. 5b)
which may be the indication for the complete utilization of the V5? species for
oxidation reaction.
TEM
TEM images of the calcined V-MCM-41 samples with Si/V atomic ratios of 100,
75, 50, and 25 are shown in Fig. 6a–d. A highly ordered mesoporous framework
with hexagonal arrays of cylindrical channels of the synthesized samples is
confirmed by TEM images [27]. These are virtually regular hexagonal arrays of fine
pore arrangement existing in these samples. This ordered arrangement, typical for
the MCM-41 materials, confirms the XRD data.
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8. 476 C. Mahendiran et al.
a
b
c
d
0 2000 4000 6000 8000
Magnetic field strength (Gauss)
Fig. 4 EPR spectra of as-synthesized catalysts (a) V-MCM-41 (25), (b) V-MCM-41 (50), (c) V-MCM-
41 (75), (d) V-MCM-41 (100)
Fig. 5 EPR spectra of catalysts (a) as-synthesized V-MCM-41 (50) and (b) V-MCM-41 (50) spent
Activity of V-MCM-41 catalyst
The activity of V-MCM-41 (50) catalyst was studied for the vapor phase oxidation
of o-xylene at 573 K with the flow rate of o-xylene 5.87 h-1 (WHSV) and CO2-free
air 0.02 mol h-1 over a period of 7 h. The results are illustrated in Fig. 7. The
percentage conversion and selectivity increased from 1 to 2 h and then decreased up
to 5 h. Beyond 5 h, the catalyst attained steady state activity. The initial increase in
conversion from 1 to 2 h is attributed to oxidation of V4? to V5?, which is necessary
for oxidation. The decrease in trend up to 5 h may be due to some carbon
deposition. Under this steady state reaction conditions, the activities of the catalysts
with varying Si/V ratios are compared.
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9. V-Mn-MCM-41 catalyst 477
Fig. 6 TEM pictures of a V-MCM-41 (100), b V-MCM-41 (75), c V-MCM-41 (50), d V-MCM-41 (25)
In order to find out the optimum vanadium content, the vapor phase oxidation of
o-xylene was carried out at 573 K on V-MCM-41 catalyst with varying vanadium
content (Si/V ratio 25, 50, 75 and 100) and the results are given in Fig. 8. It is
observed that the conversion o-xylene increases with Si/V ratio till V-MCM-41
(50). Obviously, more vanadium loading can increase o-xylene conversion because
of the increased amount of available active sites. This is revealed from the low
intensity of DRUV-Vis spectral bands of V-MCM-41 (25) catalyst around 260
and 340 nm corresponding to V5? (Fig. 3a, b) compared to that of V-MCM-41 (50).
The optimum ratio is around 50. V-MCM-41 (50) exhibited the maximum catalytic
activity. However, beyond the Si/V ratio 50, there is a decrease in trend observed
with respect to its conversion. This may be because of the lack of dispersion of
vanadium even though available in large quantity. The decrease in conversion at
high Si/V value may be attributed to the decrease in the concentration of V5? active
sites as it is evident from the DRUV-Vis spectra where a decrease in the absorbance
intensity is noticed with increase in Si/V ratio from 50 to 100. Hence, the high
activity of V-MCM-41 (50) may be attributed to the availability of higher number
of V5? in V-MCM-41 (50) than in V-MCM-41 (75) and V-MCM-41 (100).
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10. 478 C. Mahendiran et al.
Fig. 7 Effect of reaction time on the oxidation of o-xylene. Reaction conditions: temperature = 573 K,
weight of V-MCM-41 (Si/V = 50) = 0.3 g, WHSV = 5.87 h-1 and flow rate of air 0.02 mol h-1
The dispersion and amount of V5? become important in order to account for high
conversion of o-xylene. The same trend was registered for the selectivity of phthalic
anhydride. The selectivity of o-toluic acid (OTA) remained reverse trend to that
of phthalic anhydride selectivity; hence it might be considered as the major
intermediate for phthalic anhydride formation as showed in the reaction scheme.
Based on the activity study and characteristics of catalysts, the vapor phase
oxidation of o-xylene is proposed to take place as suggested in reaction scheme
(Scheme 1). According to the scheme, molecular oxygen is activated by framework
vanadium. The activated O2 is inserted between carbon and hydrogen bond of the
methyl group in o-xylene. The resulting alcohol is rapidly oxidized to o-tolaldehyde
which is also subsequently oxidized to o-toluic acid. The same process is also
repeated on adjacent methyl group to yield phthalic acid. The product is
subsequently oxidized to phthalic anhydride.
Comparison of the catalyst supports
The activity of V-MCM-41 (50), Mn-MCM-41 (50) and V-Mn-MCM-41
(V:Mn = 50:50), was measured at 573 K with the WHSV of o-xylene 5.87 h-1
(WHSV). The results are compared under the optimized reaction conditions to
understand the influence of various metals on the oxidation reaction and presented
in Fig. 9. Among the three catalysts, it is the V-MCM-41 (50) catalyst that exhibited
maximum activity. The reason for the high activity of V-MCM-41 (50) may be due
to the availability of silica matrix V5? in MCM-41which is evident from DRUV-Vis
123
11. V-Mn-MCM-41 catalyst 479
Fig. 8 Effect of Si/V ratio on the oxidation of o-xylene over V-MCM-41. Reaction conditions:
temperature = 573 K, catalyst weight = 0.3 g, WHSV = 5.87 h-1 and flow rate of air 0.02 mol h-1;
reaction time = 120 min
O O . CH2 H
O O
V O2 V CH2 OH
O O O O CH3
O O
Si Si Si Si CH3
Si Si
fast
CHO
CH3
O
C COOH COOH
Repeated
O
fast
C COOH CH3
O
Scheme 1 Vapor phase oxidation of o-xylene to phthalic anhydride
123
12. 480 C. Mahendiran et al.
100
% of Conversion & Selectivity 80
60
Conversion
40
Selectivity
20
0
V-MCM-41- Mn-MCM-41- V-Mn-MCM-41-(50+50)
Fig. 9 Comparison of activity of the catalysts for the oxidation of o-xylene. Reaction conditions:
temperature = 573 K, weight of the catalyst = 0.3 g, WHSV = 5.87 h-1 and flow rate of air
0.02 mol h-1; reaction time = 120 min
spectra (Fig. 3). Further evidence of the elemental analysis results also (Table 1,
ICP-AES) reveals that decrease the Si/V ratios (from 100 to 25) there is increase the
incorporated metal content into the silica matrix. Hence, it is concluded that silica
matrix V5? was shown to be more active for the oxidation of o-xylene to phthalic
anhydride [28]. Manganese (Mn) incorporated into the MCM-41 is expected to
support oxidative dehydrogenation of hydrocarbons because of the presence of
successive acidic and redox sites. However, during the oxidative dehydrogenation
of o-xylene, the strong aromaticity will be lost significantly. Hence, Mn
incorporated MCM-41 does not support the oxidation reaction of o-xylene to
phthalic anhydride under these experimental conditions. Finally, based on the
literature, it can be understood that the poor activity of V-Mn-MCM-41 may be due
to the presence of lower number of silica matrix V5? in V-Mn-MCM-41 catalyst.
Conclusions
From the scrutiny of the above work, the following conclusions can be drawn:
1. Mesoporous V-MCM-41 molecular sieves with Si/V ratio 25, 50, 75 and 100
contains vanadyl ions (VO2?) in the as-synthesized form, whereas on
calcination, vanadyl ions (VO2?) is converted into highly dispersed V5?
species with tetrahedral coordination.
2. Enhancement of the activity of MCM-41 for the vapor phase oxidation of o-
xylene is achieved by incorporating vanadium. The high activity of V-MCM-41
(50) for phthalic anhydride formation could be accounted due to the presence of
large amount of well dispersed V5? on V-MCM-41. Both UV-Vis DRS and
123
13. V-Mn-MCM-41 catalyst 481
EPR spectroscopies provide valuable information about the surface structure of
V-MCM-41 catalysts.
3. When the activity of vanadium loaded MCM-41 is compared with Mn and
bimetal (V&Mn) loaded MCM-41, it is the vanadium that is the most preferred
metal for oxidation reaction.
Acknowledgments The authors would like to thank the Defence Research and Development
Organization (DRDO) of India for providing financial support.
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