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 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In Situ Infrared Study of G S L S Adsorption and Photocatalytic Processes written by Duane D. Miller and published by . This book was released on 2009 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Coal fired power plants release large quantities of CO2 and trace amounts of SO2 into the atmosphere, affecting global warming and worldwide climate change. CO2 is a concern as a greenhouse gas in relation to global temperature raise. SO2 is a concern in environmental protection as a precursor for acid rain. The impact of CO2, SO2, and H2S on the environment demonstrate the removal process is a subject of study of great importance. Removal of these gases has been focused on the development of amine based sorbents for sequestration by the adsorption and desorption process. Fourier Transform Infrared spectroscopy (FTIR) is a powerful tool for investigating the adsorption/desorption process and structure of adsorbing molecules. The application of FTIR, coupled with ab initio quantum chemistry, can provide a direct means for understanding the interactions that occur during chemisorption. The removal of CO2 and H2S by an amine based sorbent has been studied. The hypothesis for this study is to investigate the use of polyethylene glycol (PEG) to promote tetraethylenepentamine (TEPA) CO2 and H2S removal capacity. It is thought that the use of PEG may improve the catalytic adsorption capacity through hydrogen bonding. This study used in situ FTIR and ab initio quantum chemistry to investigate the adsorption and desorption processes during CO2 and H2S capture at the molecular level. The FTIR results determine that PEG interacts with the primary amine functional groups of TEPA dispersing the adsorption sites leading to improved adsorption capacity for CO2 and H2S. Ab initio quantum chemistry determined that PEG lowers the binding energy of CO2 and H2S leading to a lower desorption temperature. Removal of the nauseous gas SO2 by an amine based sorbent is studied. The hypothesis investigated the use of 1,3-phenylenediamine low basic property for creating a reusual solid amine based sorbent for SO2 removal. It is thought that the low basic property of the aromatic amine will allow the effective SO2 adsorption and desorption at low temperature. This study used in situ FTIR spectroscopy to investigate the adsorption and desorption processes during SO2 capture. The result of this study determined that 1,3-phenylenediamine basic property allowed SO2 adsorption and desorption at 373 K, however, sorbent deactivation occurs. The in situ UV-Visible spectroscopic technique provided insight that deactivation is the result of agglomeration of 1,3-phenylenediamine. Addition of PEG prevent the agglomeration and improved the adsorption capacity of 1,2-phenylenediamine through hydrogen bonding with the primary amine functional group. Amine based sorbents have proven as an effective and economic process for the removal of CO2 and the hazardous gases H2S and SO2. Advancing knowledge in the area of amine based sorbents will improve our ability for hazardous waste management. Hazardous waste management may also be achieved by the oxidation and reduction (redox) of toxic materials. TiO2 based catalysts have the ability to oxidize a number of hazardous materials to nontoxic products where TiO2 has become the benchmark semiconductor in photo-detoxification of contaminated water. This work also investigates the photocatalytic dehydrogenation process over TiO2 based catalysts. The hypothesis investigated the relationship of the photogenerated electrons and adsorbed species during the photocatalytic dehydrogenation of 2-propanol. It is thought that the interaction of the photogenerated electrons and adsorb species may be elucidated from the reaction mechanism during the photocatalytic dehydrogenation of 2-propanol. 2-propanol is used as a model compound because it provides a simple and standard way to measure the photocatalytic activity during the gas/liquid phase reactions. This study suggest that in the presence of adsorbed H2O, the dehydrogenation process proceeded by a hydroxyl radical species while in the absence of adsorbed H2O the active species is an adsorbed ion. Au/TiO2 unique ability to generate adsorbed oxygen ions resulted in higher catalytic activity in the absence of adsorbed H2O under UV-irradiation. The reaction pathway for the photocatalytic dehydrogenation of 2-propanol is strongly dependent on the coverage of surface H2O."--Abstract.

Download or read book In situ Spectroscopic Studies of Adsorption at the Electrode and Electrocatalysis written by Shi-Gang Sun and published by Elsevier. This book was released on 2011-08-11 with total page 559 pages. Available in PDF, EPUB and Kindle. Book excerpt: In-Situ Spectroscopic Studies of Adsorption at the Electrode and Electrocatalysis is a new reference on in-situ spectroscopic techniques/applications, fundamentals of electrocatalysis at molecule level, and progresses within electrochemical surface science. Presenting both essential background knowledge at graduate level and original research within the fields of spectroscopy, electrochemistry, and surface science. Featuring 15 chapters by prominent worldwide scholars, based on their recent progress in different aspects of in-situ spectroscopy studies, this book will appeal to a wide audience of scientists. In summary this book is highly suitable for graduates learning basic concepts and advanced applications of in-situ spectroscopy, electrocatalysis and electrode adsorptions. * Written by the most active scientists in the fields of spectroscopy, electrochemistry and surface science* Essential background knowledge for graduate students* A modern reference of cutting-edge scientific research

Download or read book In situ Infrared Studies of Adsorbed Species in CO2 Capture and Green Chemical Processes written by Long Zhang and published by . This book was released on 2016 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Clean energy and environment is a 21st-century contemporary challenge we human being faces. Tremendous effort has been paid to explore and develop technologies to produce green energy, to reduce the emissions of wastes, and to utilize these wastes and renewable sources. Catalysis technologies and CO2 capture and utilization technologies are among the most important stepping stones to achieve the challenging goals to secure the environment for human survival and development. The advancement in these technologies requires a molecular-level or quantum-level fundamental understanding of the processes involved. One critical aspect of importance is the nature of the adsorbed species and their evolution in these green chemical processes. Fourier transform infrared (FTIR) spectroscopy is a powerful and versatile tool that can provide the insights to address these scientific issues. This dissertation, with a focus on the applications of in-situ FTIR spectroscopy, discusses about a few important topics in CO2 capture and other green processes, including (i) the catalytic asymmetric hydrogenation of a-amino ester, a potential chemical building block and starting material for biocompatible polymers, (ii) the oxidative and CO2-induced degradation of supported polyethylenimine (PEI) adsorbents for CO2 capture, (iii) the utilization of CO2 by the catalytic conversion of CO2 to carbonates, a precursor for polycarbonates and polyurethanes, (iv) the catalytic conversion of 2,3-butanediol to 1,3-butadiene, the monomer for synthetic rubbers, and (v) the electron-induced IR absorbance in photocatalytic processes on TiO2. A wide array of FTIR techniques, including diffuse reflectance, attenuated total reflectance, and transmission IR has been applied. The FTIR results revealed the vital hydrogen bonding interactions in the catalytic asymmetric hydrogenation of a-amino ester which led to the prochiral structures. The oxidative degradation and CO2-induced degradation pathways were elucidated with the help of various FTIR studies conducted. The mechanism of the oxidative degradation of amines was proposed for the first time that the solid amines underwent the deactivation to imines and further oxidation to amides. The effects of amine loading, temperature, and water vapor on CO2-induced degradation were clarified. The FTIR spectra evidenced the successful conversion of CO2 to dimethyl carbonate and 2,3-butanediol to 1,3-butadiene, and helped the comprehension of the kinetics and the nature of the dehydrating agent in the reactions. In-situ FTIR was also used to differentiate the contributions from the conduction-band electrons and shallow-trapped electrons to the polaronic light absorbance. A modelling method was developed to analyze the IR spectra. The modelling results revealed the correlation of these differently sourced absorbance and the generation of photocurrent and the charge transportation process in photocatalysis.

Download or read book Adsorption and Catalysis on Oxide Surfaces written by M. Che and published by Elsevier. This book was released on 1985-07-01 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Symposium was held to honour the memory of the late Dr. A.J. Tench who made numerous important contributions to our knowledge of the structure, reactivity and adsorption properties of oxide surfaces. This volume contains an up-to-date picture of adsorption and catalysis on oxide surfaces, not in the form of a comprehensive review but in its living aspects of work in progress. It describes detailed studies on the determination of the coordination surface ions, particularly oxide ions, by photoluminescence and reflectance spectroscopy, on the identification of adsorbed species by magnetic optical or surface techniques and on catalysis, with emphasis on new concepts such as catalysis involving excited states or structure sensitive reactions.Professionals working in the industrial and academic laboratories will find the book particularly useful as it provides a state-of-the-art account of our understanding of the structure and adsorption characteristics of oxide surfaces. Contained in the book are first class research papers by leading exponents in this field. A very important issue is that the book highlights for the first time the importance of excited states and structure sensitivity in determining the behaviour of oxide surfaces.

Download or read book Near Field Optics and Surface Plasmon Polaritons written by Satoshi Kawata and published by Springer Science & Business Media. This book was released on 2001-06-20 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: This up-to-date overview describes in detail the physics of localized surface plasmon polaritons excited near fine metallic structures and the principles of near-field optics and microscopy related to this localized field. It also covers wider fields, from local spectroscopy to atom manipulation.

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 Surface Science of Catalysis written by Daniel J. Dwyer and published by . This book was released on 1992 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents an excellent overview of the impact of surface science on the field of catalysis. Explores the exciting new advances in surface science and catalysis, which for the first time allow for direct spectroscopic and kinetic observation of surface reactions. Twenty-two chapters cover fundamental aspects of catalytic reactions at surfaces, applications of surface probes to the study of catalytic reactions and kinetics, and novel aspects of catalytic reactions at surfaces. Highlights the success of surface science techniques in the study of industrially important catalytic processes, including hydrogenation of CO to produce hydrocarbons and methanol, the oxidation of methane to methanol, and conversions of CO to carbon dioxide.

Download or read book Plasma Catalysis written by Annemie Bogaerts and published by MDPI. This book was released on 2019-04-02 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.

Download or read book Heterogeneous Catalytic Redox Reactions written by Vladislav Sadykov and published by Walter de Gruyter GmbH & Co KG. This book was released on 2019-10-21 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current book brings together cutting-edge research in the area of heterogeneous catalytic redox processes. The first part of the book covers the catalytic properties of transition metal oxides and the techniques for catalysts preparation, such as mechanochemistry, plasmochemistry, hydrothermal treatment, etc. Further the authors focus on mechanisms of heterogeneous redox reactions followed by the overview of industrial applications.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Air Pollution Abstracts written by and published by . This book was released on 1971 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sunshine and Vitamin D Volume 1 of 2 EasyRead Super Large 24pt Edition written by and published by ReadHowYouWant.com. This book was released on with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In Situ Fourier Transform Infrared Spectroscopy of Adsorbed Species on Mixed Metal Oxide Catalysts for Higher Alcohol Synthesis written by Ahmet Baysar and published by . This book was released on 1985 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Combined in Situ Attenuated Total Reflection Infrared and UV is Spectroscopic Study of Alcohol Oxidation Over Pd Al sub 2 sub O sub 3 sub written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In situ attenuated total reflection (ATR) infrared and UV- is spectroscopy are combined to yield simultaneous time-resolved information on dissolved reaction products, adsorbed species, and the catalyst during the oxidation of ethanol and 2-propanol on a 5% Pd/Al2O3 catalyst. The oxidation is initiated by change from hydrogen- to oxygen-saturated solvent flow. 2-Propanol oxidation is observed only in the transient period, whereas ethanol oxidation is also observed in the steady state. This may be ascribed to overoxidation of the catalyst in the former case. In a mixture of the two alcohols the same thing is observed. Competitive adsorption in the steady state may explain this behavior. For ethanol oxidation ethyl acetate is also observed during the transient period. The UV- is spectra reveal a fast reversible change of the catalyst with switching between hydrogen and oxygen and a slow irreversible change during ethanol oxidation. The latter is ascribed to the change in Pd particle structure, which hardly affects, however, catalyst activity on the time scale of about 1 h.

Download or read book Multiscale and Innovative Kinetic Approaches in Heterogeneous Catalysis written by Pascal Granger and published by MDPI. This book was released on 2019-07-11 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Kinetics and reactor modeling for heterogeneous catalytic reactions are prominent tools for investigating and understanding catalyst functionalities at nanoscale and the related rates of complex reaction networks. This book illustrates some examples related to the transformation of simple to more complex feedstocks, including different types of reactor designs, i.e., steady-state, transient plug flow reactors, and TAP reactors for which there is sometimes a strong gap in the operating conditions from ultra-high-vacuum to high-pressure conditions. In conjunction, new methodologies have emerged, giving rise to more robust microkinetics models. As exemplified, they include the kinetics and the dynamics of the reactors and span a large range of length and time scales. The objective of this Special Issue is to provide contributions that can illustrate recent advances and novel methodologies for elucidating the kinetics of heterogeneous reactions and the necessary multiscale approach for optimizing the reactor design. This book is dedicated to postgraduate and scientific researchers, and experts in heterogeneous catalysis. It may also serve as a source of original information for the elaboration of lessons on catalysis for Master students.

Download or read book Electrocatalysis written by Minhua Shao and published by Springer Nature. This book was released on 2020-03-20 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience.Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.