Download or read book In Situ Infrared Studies of Reactions of H2 and C2H4 with Adsorbed CO on Rh and Co Catalysts written by Raja Krishnamurthy and published by . This book was released on 1992 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1992-10 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Frontiers in Catalysis Parts A C written by L. Guczi and published by Elsevier. This book was released on 1993-04-20 with total page 2955 pages. Available in PDF, EPUB and Kindle. Book excerpt: These volumes comprise the proceedings of the major international meeting on catalysis which is held at 4 year intervals. The programme focussed on New Frontiers in Catalysis including nontraditional catalytic materials and environmental catalysis. The contributions cover a wide range of fundamental, applied, industrial and engineering aspects of catalysis. The extensive range of highly efficient industrial techniques for observing and characterizing catalytically important surfaces is evident.The programme covered the following sessions: Mechanism, theory, in situ methods; Catalytic reaction on atomically clean surfaces; Catalytic reaction on zeolites and related substances; New methods and principles for catalyst preparation; Hydrotreatment reactions (HDS, HDN); Characterization of catalysts, application of novel techniques; Selective oxidation; New catalytic aspects of heteropoly acids and related compounds; Reaction of hydrocarbons; Nontraditional catalytic materials; Fuel upgrading; Alkane activation; Acid-base catalysis; New selective catalytic reactons, fine chemicals; Environmental catalysis; Industrial catalysis, deactivation, reactivation; Synthesis from syngas; Electrocatalysis; Photocatalysis.The invited lectures and 433 papers included in these volumes present an update on all areas of catalysis and applications.

Download or read book In Situ Infrared Study of Adsorbed Species During Catalytic Oxidation and Carbon Dioxide Adsorption written by Rajesh A. Khatri and published by . This book was released on 2005 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fossil Energy Update written by and published by . This book was released on 1982 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Organometallic Chemistry Molecular Approaches to Surface Catalysis written by Jean-Marie Basset and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface organometallic chemistry is a new field bringing together researchers from organometallic, inorganic, and surface chemistry and catalysis. Topics ranging from reaction mechanisms to catalyst preparation are considered from a molecular basis, according to which the "active site" on a catalyst surface has a supra-molecular character. This. the first book on the subject, is the outcome of a NATO Workshop held in Le Rouret. France, in May. 1986. It is our hope that the following chapters and the concluding summary of recommendations for research may help to provide a definition of surface organometallic chemistry. Besides catalysis. the central theme of the Workshop, four main topics are considered: 1) Reactions of organometallics with surfaces of metal oxides, metals. and zeolites; 2) Molecular models of surfaces, metal oxides, and metals; 3) Molecular approaches to the mechanisms of surface reactions; 4) Synthesis and modification of zeolites and related microporous solids. Most surface organometallic chemistry has been carried out on amorphous high-surf ace-area metal oxides such as silica. alumina. magnesia, and titania. The first chapter. contributed by KNOZINGER. gives a short summary of the structure and reactivity of metal oxide surfaces. Most of our understanding of these surfaces is based on acid base and redox chemistry; this chemistry has developed from X-ray and spectroscopic data, and much has been inferred from the structures and reactivities of adsorbed organic probe molecules. There are major opportunities for extending this understanding by use of well-defined (single crystal) oxide surfaces and organometallic probe molecules.

Download or read book Unraveling Mechanisms and Quantifying Active Sites by Using In situ and Ex situ Infrared Spectroscopy written by Shao-Chun Wang (Ph.D.) and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The molecular-level understanding of surface sites and reaction mechanisms is key for the development of the field of heterogeneous catalysis. Infrared spectroscopy, studying molecular vibrations, is widely used to investigate the structures of surface-bound species in heterogeneous catalysts. Heterogeneous catalytic reactions proceed via adsorption of the reagent(s), surface reaction, and desorption of the product(s), leading to complex in-situ or operando IR spectra. However, the information of active species is usually concealed by spectator species which do not participate in the catalytic cycle. Modulation excitation spectroscopy serves as a tool to increase the signal-to-noise level and to differentiate between the active species and spectator species during a catalytic reaction. In Chapter 2, we report on the use of diffuse reflectance FT-IR spectroscopy (DRIFTS) with a modulation excitation (ME) approach followed by mass spectrometry (MS) to investigate the reaction of ethanol to n-butanol over hydroxyapatite (HAP). The approach allows for a vibrational characterization of the active surface species and the formulation of a consistent mechanism. Based on our experimental observations, Ca2+/OH- can be put forward as the main active site for the aldol condensation. POH/OH- acid-base pair is proposed as the active site for the Meerwein-Ponndorf-Verley (MPV) direct hydrogen transfer for the n-butanol formation.In Chapter 3, we describe the use of NO as a probe molecule in low-temperature IR spectroscopy to identify and quantify copper species in the state-of-the-art commercial NOx abatement catalyst, Cu ion-exchanged chabazite zeolite. While bulk analysis can reveal the total concentration of copper in the catalyst, the amount of ion-exchanged copper is more difficult to determine due to the appearance of non-exchanged Cu species, CuOx. Molecules such as carbon monoxide (CO) and nitric oxide (NO) are routinely used as a probe to investigate the copper speciation in order to draw structure-activity correlations. However, NO is easy to decompose and reacts with copper species at ambient temperature, causing complexity in IR spectra. Here, we develop NO adsorption IR spectroscopy at cryogenic conditions to avoid the undesired reactions. The observed IR peaks for Cu+(NO)2 and Cu2+(NO) species can be used to quantify the amount of exchanged copper species in a broad range of samples, including a commercial wash-coated honeycomb. Calibration curves for Cu+(NO)2 and Cu2+(NO) are determined for copper loadings up to 3.99 wt% with silica to alumina ratio of 16-22 and quantitative agreement with complementary hydrogen temperature-programmed reduction (H2-TPR) results is established. Our methodology allows us to identify different Cu species in Cu-CHA, such as Z2Cu(II), Z1Cu(II)OH and Cu dimers, based on their distinct IR signatures. In addition, the perturbed T-O-T framework vibration - characterized at 400 oC - can also be used as a complementary method to quantify Z2Cu(II) species. This work demonstrates that cryogenic NO-IR is a facile technique to identify and quantify the exchanged copper species in Cu-CHA to accelerate catalyst development. In chapter 4, we extend the NO-IR method to characterize the ion-exchanged species in Cu-ZSM-5 and Fe-CHA. The adsorbed NO shows distinct IR characteristics for exchanged copper species at 1914 cm-1 and the calibration curve for Cu2+ species for estimating high Cu-loading Cu-ZSM-5 is determined. In the case of Fe-CHA, the NO-IR is not efficient due to the formation of NO monomer and trimer on copper species, causing complexity in the IR spectra. Carbon monoxide (CO) is then applied as an alternative probe molecule. The results of CO-IR for Fe-CHA showed more defined IR features for Fe2+(CO) than in NO-IR. With this toolbox in hand, the calibration curve for the concentration of Fe2+ in Fe-CHA by CO-IR is then established. Perspectives for future research are outlined in Chapter 5, the preliminary results for a Cu-Ga binary catalyst for methanol production from CO2 hydrogenation was tested by using the DRIFTS cell with ambient pressure. However, due to thermodynamic limitation, the reaction favors reverse water gas shift under ambient pressure. The newly designed operando DRIFTS cell allows to minimize the exchange time of concentration modulation and have the capability of holding at high pressure (> 25 bar) and high temperature (> 250 oC) which is suitable for investigating the heterogeneous catalysts for CO2 hydrogenation. With the well-establish tool, we will be able to investigate surface-bound species and reaction mechanisms under working conditions by IR spectroscopy. Not only can gas phase catalytic reactions be studied by DRIFTS, but heterogeneous catalytic reactions in liquid phase can also be investigated by attenuation total reflection IR spectroscopy (ATR-IR). Competitive adsorption with reactants and solvents is especially important in the case of (micro-) porous catalysts where the composition inside the pores can be very different from the bulk due to size exclusion and confinement effects. ATR-IR with the ME approach can shed light on mechanistic insights for liquid phase reactions. Lastly, with the success of low temperature NO and CO-IR method development, characterizing different metal ion-exchanged zeolites for various applications such as methane to methanol, syngas to dimethyl ether, and NOx abatement is crucial for structure-reactivity correlation. Ultimately, low temperature NO and CO-IR can be established as facile techniques to identify and quantify metal ion species located in different types of zeolites.

Download or read book The Effect of Chemical Additives on the Synthesis of Ethanol written by and published by . This book was released on 1989 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to elucidate the role of various chemical additives on ethanol synthesis over Rh- and Ni-based catalysts. Chemical additives used for this study will include S, P, Ag, Cu, Mn, and Na which have different electronegativeities. The effect of additives on the surface state of the catalysts, heat of adsorption of reactant molecules, reaction intermediates, reaction pathways, reaction kinetics, and product distributions is/will be investigated by a series of experimental studies of NO adsorption, reactive probing, steady state rate measurement, and transient kinetic study. CO insertion is known to be a key step to the formation of acetaldehyde and ethanol from CO hydrogenation. Reaction of ethylene with syngas is used as a probe to determine CO insertion capabilities of metal catalysts. During the sixth quarter of the project, the mechanism of CO insertion on Ni/SiO2 was investigated by in-situ infrared spectroscopy. Ni/SiO2, a methanation catalyst, has been shown to exhibit CO insertion activity. In situ infrared studies of CO/H2 and C2H4/CO/H2 reactions show that the carbonylation of Ni/SiO2 to Ni(CO)4 leads to an inhibition of methanation in CO hydrogenation but an enhancement of formation of propionaldehyde in C2H4/CO/H2 reaction. The results suggest that the sites for propionaldehyde formation is different from those for methanation.

Download or read book In Situ Infared i e Infrared Studies of Catalytic Partial Oxidation written by Chundi Cao and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytic partial oxidation (CPO) has received considerable interest recently both as a way to utilize remote natural gas resources and to provide H[subscript]2 for a fuel cell. Studies on the reactions at lower temperatures and transient conditions were performed, which can provide insights on the mechanism of CPO at high reactions, particularly on the role of the chemical and physical state of the noble metal catalyst. In this work, ignition of methane CPO on Pt/Al[subscript]2O[subscript]3 and Rh/Al[subscript]2O[subscript]3 catalysts and methanol CPO on Pt/Al[subscript]2O[subscript]3 catalysts were studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ignition mechanism study of CH4 on Pt/Al[subscript]2O[subscript]3 showed that oxygen mainly covers the surface until ignition. Competition between the two reactants is assumed. The heat of adsorption of oxygen is a key factor for ignition of the methane partial oxidation reaction on Pt/Al[subscript]2O[subscript]3. The ignition mechanism on Rh/Al[subscript]2O[subscript]3 was found to be different from Pt/Al[subscript]2O[subscript]3. The oxidation state of the catalyst changed significantly as the temperature was raised towards the ignition. An oxidized rhodium state, Rh[superscript]n+, progressively formed as the temperature was increased while Rh[superscript]0 decreased. In addition, a greater amount of Rh[supercript]n+ was found when the oxygen concentration in the feed was higher. From these results, it is hypothesized that ignition of methane CPO on Rh/Al[subscript]2O[subscript]3 is related to the accumulation of the Rh[superscript]n+ state. Dissociation adsorption of methanol occurs on both Al2O3 and Pt/Al[subscript]2O[subscript]3. It is suggested that formate was one of the important intermediates in the reaction pathway. Oxygen species play a key role in the formation of formate on the catalysts, and it also affects the product composition. Formate mainly decomposed into CO, which is the dominant source for CO[subscript]2 production in the reactions at higher temperatures.

Download or read book Chemicals from Synthesis Gas written by R.A. Sheldon and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The origins of the petrochemical industry can be traced back to the 1920s when simple organic chemicals such as ethanol and isopropanol were first prepared on an industrial scale from by-products (ethylene and propylene) of oil refining. This oil-based petrochemical industry, with lower olefms and aromatics as the key building blocks, rapidly developed into the enormous industry it is today. A multitude of products that are indispensible to modern day society, from plastics to pharmaceuticals, are derived from oil and natural gas-based hydro carbons. The industry had its heyday in the '50s and '60s when predictions of future growth rates tended to be exponential curves. However, two developments that took place in the early '70s disturbed this simplistic and optimistic view of the future. Firstly, the publication of the report for the Cub of Rome on the 'Limits to Growth' emphasized the finite nature of non-renewable fossil fuel resources. Secondly, the Oil Crisis of 1973 emphasized the vulnerability of an energy and chemicals industry that is based largely on a single raw material.

Download or read book Promoted Rh SiO2 Catalysts for NO CO and CO Insertion Reactions written by Girish Srinivas and published by . This book was released on 1994 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Renewable Hydrogen Technologies written by Luis M Gandia and published by Newnes. This book was released on 2013-05-03 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fields covered by the hydrogen energy topic have grown rapidly, and now it has become clearly multidisciplinary. In addition to production, hydrogen purification and especially storage are key challenges that could limit the use of hydrogen fuel. In this book, the purification of hydrogen with membrane technology and its storage in "solid" form using new hydrides and carbon materials are addressed. Other novelties of this volume include the power conditioning of water electrolyzers, the integration in the electric grid of renewable hydrogen systems and the future role of microreactors and micro-process engineering in hydrogen technology as well as the potential of computational fluid dynamics to hydrogen equipment design and the assessment of safety issues. Finally, and being aware that transportation will likely constitute the first commercial application of hydrogen fuel, two chapters are devoted to the recent advances in hydrogen fuel cells and hydrogen-fueled internal combustion engines for transport vehicles. - Hydrogen from water and biomass considered - Holistic approach to the topic of renewable hydrogen production - Power conditioning of water electrolyzers and integration of renewable hydrogen energy systems considered - Subjects not included in previous books on hydrogen energy - Micro process technology considered - Subject not included in previous books on hydrogen energy - Applications of CFD considered - Subject not included in previous books on hydrogen energy - Fundamental aspects will not be discussed in detail consciously as they are suitably addressed in previous books - Emphasis on technological advancements - Chapters written by recognized experts - Up-to date approach to the subjects and relevant bibliographic references

Download or read book Precision Process Technology written by M.P.C. Weijnen and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt: New process technology strategies are required to cope with the future. Fossil feedstocks are losing ground in favour of renewable feedstocks and secondary resources. Conventional processing routes using thermal `sledgehammer' techniques are replaced by highly selective (bio)catalytic conversions. The future process engineer is neither allowed to think in terms of unit operations, nor to take for granted the conventional practice of continuous steady state processing. Hybrid systems and transient operations are more and more frequently encountered. The continuing impressive progress being made in process modelling and control will revolutionize the process industries. In the new generation of chemical production processes the keyword is precision. Precision in terms of selectivity and of efficiency, is required to maximize the utilisation of materials and energy. Moreover, enhanced precision is needed to exploit the quality of materials and energy to the full extent. Only by reducing the squandering of materials, energy and quality will a harmonious relationship be established between the process industries, the economy, and the environment. Process integration, as well as an integrated effort by the disciplines involved in process technology, will be of crucial importance in attaining the goals of precision process technology. These emerging strategies involve an active exchange of tools and ideas between a variety of disciplines, not only in plant design and operation, but even more in the early stages of process development and design. By looking from various angles at what the future has in store for the process industries, this volume systematically lifts the corners of the veil and may inspire to establish a new tradition of precision in process technology.

Download or read book Molecular Spectroscopy of Oxide Catalyst Surfaces written by Anatoli Davydov and published by John Wiley & Sons. This book was released on 2003-06-27 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt: As in the study of transition metal complexes in solution, molecular spectroscopic methods - principally the infrared, ultraviolet/visible and electron spin resonance spectroscopies - have played key roles in establishing the concepts of coordination chemistry occurring at the surfaces of solids. This book describes the development of the principals of coordination chemistry of oxide surfaces using analyses of data obtained by these methods. The nature, properties, concentration of the surface adsorption centers and their influence on the character of interaction with different molecules are investigated. The book commences with an account of the basic theoretical principles and experimental techniques of the various spectroscopy methods, with special attention devoted to in situ measurements where the oxide or catalyst sample is in contact with the adsorbate or the reactant. A detailed account is presented of the methods for characterizing the oxidation state and degree of coordination of surface cations and oxygen anions by the adsorption of probe molecules. The complexation of many inorganic, organometallic and organic molecules with different oxide systems is critically examined, and a classification of formed surface compounds, based on the interaction with definite type of adsorption centers, is given. Possible mechanisms of numerous catalytic reactions, including the transformation of organic molecules over acidic catalysts via the carboionic mechanism, are discussed using the spectroscopic identifications of reaction intermediates. A comprehensive analysis of the literature on the interpretation of the spectra of surface compounds on oxides is presented. This highly illustrated and extensively referenced volume is intended for specialists working in the fields of surface physical chemistry, surface and materials sciences, and adsorption phenomena and is essential reading for those involved in the heterogeneous catalysis by transition metal-oxides.

Download or read book Process and Chemical Engineering written by and published by . This book was released on 1993 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In Situ IR Spectroscopic Studies of the CO Oxidation Reaction Over a Ruthenium Model Catalyst written by Attila Farkas and published by . This book was released on 2008 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Book of Abstracts written by American Chemical Society. Meeting and published by . This book was released on 1986 with total page 1350 pages. Available in PDF, EPUB and Kindle. Book excerpt: