Download or read book Influences of Support Material Variation on Structure and Catalytic Performance of MnxOy Na2WO4 SiO2 Catalyst for the Oxidative Coupling of Methane written by Mahmut Yildiz and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influences of Support Material Variation on Structure and Catalytic Performance of Mn X O Y Na 2 WO 4 SiO 2 Catalyst for the Oxidative Coupling of Methane written by and published by . This book was released on 2014 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of Mn Na2WO4 Catalyst on La2O3 Y2O3 and YSZ Supports for Oxidative Coupling of Methane Reaction in Fixed Bed and Solid Oxide Fuel Cell Reactors written by and published by . This book was released on 2011 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research studies the development of Mn-Na2WO4 catalysts on La2O3, Y2O3 and YSZ supports for oxidative coupling of methane reaction. It can be divided into two parts; (1) study in fixed bed reactor (FBR), and (2) study in solid oxide fuel cell reactor (SOFC). In part I, the experiments were performed using co-feeds of methane, oxygen and nitrogen inert gas at a ratio of 4:1:5 for different temperatures (973-1173 K). Mn-Na2WO4 catalyst on supports La2O3, Y2O3 and YSZ were doped with sulfur, phosphorous, and cerium in order to improve its catalytic reactivity.
Download or read book Reactivity and Characterization of Supported Noble Metal Catalysts written by Keishla R. Rivera-Dones and published by . This book was released on 2020 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytically driven processes account for over ninety percent of industrial chemical manufacturing today. Developments in manufacturing processes are largely driven by continued improvements in catalytic materials, which aim to increase production volumes while minimizing costs along with safety and environmental hazards. In order to achieve these goals, however, a rational approach in catalyst design must be pursued that aims to understand and build upon the fundamental structural, electronic, and chemical properties governing catalytic performance. To that purpose, the work presented in this dissertation makes use of kinetic experiments, theoretical models, and advanced characterization techniques to generate a fundamental understanding of noble metal surfaces employed in a variety of catalytic reaction systems. In Chapter 2, we discuss the use of N2 physisorption, CO chemisorption, and NH3 temperature programed desorption to evaluate the effect of support acidity on the reactivity profiles of various zeolite-supported Pt and Pt-Sn catalysts for the non-oxidative coupling of methane to ethylene and aromatics. Reactivity studies for Pt-Sn/H-ZSM-5 catalysts at 973 K showed that, while all catalysts produced ethylene as the primary product, increasing support acidity led to an increase in naphthalene selectivity at the expense of benzene selectivity. Volcano-shaped profiles observed for the generation of aromatic products suggest that the formation of a reactive hydrocarbon pool on acidic support surfaces could be responsible for the oligomerization of ethylene. Notably, the Pt-Sn/H-ZSM-5 (SiO2:Al2O3 = 50) catalyst was found to be comparable to the state-of-the-art Mo/H-ZSM-5 catalysts in terms of carbon product generation and resistance to coke formation. In Chapter 3, x-ray absorption spectroscopy (XAS) was used to highlight the effect of local electronic and structural environments in specially synthesized metallic catalysts. The local coordination and nearest-neighbor distance of Pd species were evaluated to understand metal dispersion and the effect of catalyst support on the extent of bimetallic particle formation in Pd, AgPd, CuPd, and AuPd catalysts synthesized by controlled surface reactions (CSR) for a variety of amination, hydrodechlorination, and hydrogenation reactions. Near-edge structure analyses were also used on these Pd catalysts, as well as on a set of Mo-containing multi-metallic catalysts prepared by atomic layer deposition (ALD) for synthesis gas conversion, to understand catalyst reducibility along with potential support and hydrogen spillover effects on the extent of metal reduction. Chapter 4 evaluates the effects of catalyst support and pretreatment conditions on the hydrogenation of acetone over SiO2-, Al2O3-, and ZSM-5-supported platinum catalysts. Pt/ZSM-5 catalysts were found to have specific conversion rates and turnover frequencies that were 2 - 3 orders of magnitude higher than those observed over Pt/SiO2 and Pt/Al2O3 catalysts, regardless of zeolite acidity or pretreatment conditions. For Pt/ZSM-5 catalysts, the higher activity was achieved by increasing calcination and decreasing reduction temperatures, likely due to the effects of these treatments on the morphology of the platinum particles. CO-FTIR measurements showed a shift to higher frequencies of the Pt-CO band in Pt/ZSM-5 catalysts compared to Pt/SiO2, which alluded to the interactions between Pt and the porous zeolite structure as a source of the activity enhancements observed. Chapter 5 introduces the use of transient kinetics studies and theoretical modeling to explore the importance of surface coverage effects in the hydrogenation of acetone over platinum. Transient models based on steady-state microkinetics using static and dynamic inclusion of surface coverage via the Langmuir and Bragg-Williams approximations, respectively, predicted notable differences in the decay profiles of the most abundant reactive intermediate (MARI) from the catalytic surface. Experimental studies using steady-state isotopic transient kinetic analysis (SSITKA) methods served to validate the theoretical predictions for transients induced by complete acetone removal from or its substitution in the reactant feed and provided tangible evidence for the importance of surface coverage effects in understanding the reactivity of platinum catalysts for acetone hydrogenation. Lastly, Chapter 6 addresses possible future research directions in the field of transient kinetics studies.
Download or read book Fundamentals Determining Activity and Product Selectivity in the Oxidative Coupling of Methane Over MnOx M2WO4 SiO2 M written by Anna Zanina and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present thesis contributes to a better understanding of one of the most promising catalysts for the oxidative coupling of methane (OCM) reaction, i.e., MnOx-Na2WO4/SiO2. Oxygen species involved in selective and unselective pathways were investigated using O2 and N2O as the oxidants. Spatially resolved and steady-state kinetic analyses combined with oxygen isotopic exchange tests were used to identify the activity-defining descriptor over M2WO4/SiO2 (M=Na, K, Rb, or Cs). The effects of alkali metal for both bi- and trimetallic compositions on activity and selectivity were establishedeng
Download or read book Investigation and Rational Design of the Catalyst support Interface in Redox Catalysis by Ceria written by Zhongqi Liu and published by . This book was released on 2020 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigating and controlling the catalyst-support interfacial interaction/structure and their effects on catalytic performance are crucial for optimizing the activity, selectivity, and durability of catalytic materials, as the heterogeneous catalytic reactions typically take place on the catalyst surface and/or at the interface between the catalyst and support. Ceria (CeO2), due to its remarkable redox activity, has been widely adopted as an active support material or promoter in a multitude of redox catalytic reactions and is the focus of this research. With the goal of bridging the predictable catalyst design-fundamental understanding of performance-practical application, we expect to develop uniform and well-defined CeO2 nanostructures as model supports to investigate the underlying mechanism of the catalyst-support interactions, and furthermore establish the correlation between interfacial structure and catalytically active sites. In Chapter 2, reducible CeO2 nanorods and nanocubes, as well as irreducible SiO2 nanospheres supported cobalt oxides (CoOx) catalysts were synthesized and comparatively studied to understand the effects of support morphology, surface defect, support reducibility, in addition to the CoOx-support interactions on their redox and catalytic properties. Chapter 3 focuses on exploring the role of “bimetallic catalysts-support interaction” over highly active CeO2 nanorods supported pure cobalt oxides and cobalt-based bimetallic oxides nanoparticles (Fe-Co, Ni-Co and Cu-Co). The interactions between cobalt with the second transition metals (Fe, Ni and Cu) are discussed as well. Nanoparticle agglomeration issue always exists when using wet-chemical methods to synthesize CeO2 nanomaterials, which is harmful for catalytic applications due to decreased surface area. Therefore, Chapter 4 presents a scalable and facile electrospinning process for designing novel fibrous structured CeO2 and one-pot synthesis of high-surface-area, thermally stable and low-temperature active Ru-CeO2 nanofiber catalysts. Besides, attracted by the great interest of three-dimensional (3D) nanoarray structures fabrication towards novel and high-performance catalyst design, as well as nanodevice applications, electrochemical deposition technique was adopted for fabricating CeO2 nanoarrays in Chapter 5. Processing factors on growing controllable CeO2 nanoarrays, including the current density, reaction temperature, stirring rate, anode and substrate types were comprehensively investigated. A scale-up synthetic strategy for CeO2 nanoarrays fabrication is developed. Besides, possible mechanisms for morphological evolution and growth of CeO2 nanoarrays are discussed.
Download or read book Impact of Synthesis Methods and Oxidizing Agents on the Catalytic Performance of Various Catalysts in the Oxidative Coupling of Methane written by and published by . This book was released on 2012 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of the Morphology of the Oxide Supports on Catalytic Performances of V SiO2 and V MgO Catalysts in Methanol Partial Oxidation written by Yuquan Lin and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Catalytic Material Design written by Ashwin Kane and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysts play an important role in the chemical industry since they help increase the speed of chemical reactions and reduce waste generation. Catalysts are typically functionalized onto the surface of solid supports such as mesoporous silica materials to ensure easy separation from the product and make the manufacturing process more economically viable. Mesoporous silica materials (pore size > 2 nm) such as SBA-15 and MCM-41 are generally preferred for supporting catalysts because of their thermal stability, robustness, and tunable pore architecture. Whereas such silica supported catalytic materials hold promise, key synthesis-structure-activity relationships remain to be discovered to enable commercial implementation of these laboratory-based catalysts. Such synthesis-structure-activity relationship studies are important to make supported catalysts more industrially viable and better performing than their homogeneous counterparts. The current work focuses on obtaining synthesis-structure-activity relationships by varying design parameters for the mesoporous silica support and catalyst analogue. This is done using two catalytic systems: (i) Knoevenagel condensation catalyzed by tertiary amines functionalized on SBA-15, and (ii) Oxidative dehydrogenation of propane catalyzed by vanadium oxides functionalized on SBA-15. Whereas the SBA-15 support is predominantly mesoporous, it also has secondary micropores (pore size
Download or read book Methane Conversion written by D.M. Bibby and published by Elsevier. This book was released on 1988-03-01 with total page 759 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume comprises the invited plenary lectures, contributed and poster papers presented at a symposium organised to mark the successful inauguration of the world's first commercial plant for production of gasoline from natural gas, based on the Mobil methanol-to-gasoline process. The objectives of the Symposium were to present both fundamental research and engineering aspects of the development and commercialization of gas-to-gasoline processes. These include steam reforming, methanol synthesis and methanol-to-gasoline. Possible alternative processes e.g. MOGD, Fischer-Tropsch synthesis of hydrocarbons, and the direct conversion of methane to higher hydrocarbons were also considered.The papers in this volume provide a valuable and extremely wide-ranging overview of current research into the various options for natural gas conversion, giving a detailed description of the gas-to-gasoline process and plant. Together, they represent a unique combination of fundamental surface chemistry catalyst characterization, reaction chemistry and engineering scale-up and commercialization.
Download or read book Support Effects Studied on Model Supported Catalysts Progress Report written by and published by . This book was released on 1993 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composition and structure of oxide support materials can change the catalytic behavior of metal and oxide catalysts. Model catalysts are being studied in which the active phase is deposited on flat oxide substrates, with emphasis on metals catalysis for automotive emissions control and acidity in supported oxides. Research is reported in the following areas: particle-size effects, support effects on ZnO and zirconia, support effects on ceria, supported oxides, and low energy ion scattering (no results in the latter).
Download or read book XAFS Techniques for Catalysts Nanomaterials and Surfaces written by Yasuhiro Iwasawa and published by Springer. This book was released on 2016-10-19 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive, theoretical, practical, and thorough guide to XAFS spectroscopy. The book addresses XAFS fundamentals such as experiments, theory and data analysis, advanced XAFS methods such as operando XAFS, time-resolved XAFS, spatially resolved XAFS, total-reflection XAFS, high energy resolution XAFS, and practical applications to a variety of catalysts, nanomaterials and surfaces. This book is accessible to a broad audience in academia and industry, and will be a useful guide for researchers entering the subject and graduate students in a wide variety of disciplines.
Download or read book Support Effects Studied on Model Supported Catalysts written by and published by . This book was released on 1993 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composition and structure of oxide support materials can change the catalytic behavior of metal and oxide catalysts. Model catalysts are being studied in which the active phase is deposited on flat oxide substrates, with emphasis on metals catalysis for automotive emissions control and acidity in supported oxides. Research is reported in the following areas: particle-size effects, support effects on ZnO and zirconia, support effects on ceria, supported oxides, and low energy ion scattering (no results in the latter).
Download or read book Property performance Relationships of Catalysts in the Oxidative Coupling of Methane written by Roman Schmack and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Property performance Correlations in the Oxidative Coupling of Methane written by Huan Wang and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Gas Conversion written by A. Holmen and published by Elsevier. This book was released on 1991-05-27 with total page 585 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings reflect the extensive fundamental and applied research efforts that are currently being made on the conversion of gas, in particular on the direct conversion of methane. The Symposium in Oslo focused on the following topics: Direct conversion of methane, Fischer-Tropsch chemistry, methanol conversion and natural gas conversion processes. The main aim was to present the state-of-the-art and progress currently being made within each of these areas. The book contains the papers presented and includes plenary lectures, short communications and posters. The papers will be of interest to scientists and engineers working in the field of gas conversion, transportation fuels, primary petrochemicals and catalysis.
Download or read book Oxidative Coupling of Methane Over Li MgO Catalyst written by Saeed M. S. Al-Zahrani and published by . This book was released on 1994 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
