Author: David Lloyd RobertsPublisher:
ISBN:
Category :
Languages : en
Pages : 346
Book Description
Identification and Characterization of Active Sites and Stable Surface Intermediates on Copper-based Methanol Synthesis Catalysts by Temperature-programmed Desorption and FTIR Spectroscopy
Author: David Lloyd RobertsIndex to American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 606
Book Description
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 564
Book Description
Doctoral Degree Recipients
Author: University of MinnesotaPublisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 254
Book Description
Comprehensive Dissertation Index
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 984
Book Description
Synthesis, Characterization, and Catalytic Properties of Interfacial Sites on Supported Metal Catalysis
Author: Insoo RoPublisher:
ISBN:
Category :
Languages : en
Pages : 156
Book Description
Previous studies have shown that the type of support and the addition of promoting materials can influence the catalytic activity and selectivity due to the formation of interfacial sites. However, the nature of the active sites and the reaction mechanisms governing these catalytic reactions are not known in detail. This is primarily because the synthesis of catalysts by traditional methods produces a wide distribution of metal particle sizes and compositions, impeding the accurate assessment on the nature of the surface, the active sites, and the catalytic behavior. Accordingly, this thesis presents the new synthetic route developed to prepare bimetallic nanoparticles with controlled particle size and interfacial sites to achieve an effective link between characterizations and reactivity. This thesis also focuses on elucidating catalytic active sites with well-defined catalysts by developing approaches to estimate the concentrations and intrinsic activity of monometallic and interfacial sites. In Chapter 3, we discuss the synthesis of well-defined Cu catalysts synthesized by controlled surface reactions (CSR) and atomic layer deposition (ALD) methods containing varying amounts of zirconia for the selective conversion of ethanol to ethyl acetate and for methanol synthesis. We found that the dominant active sites for the production of acetaldehyde are monometallic Cu, while Cu-ZrO2 interfacial sites are necessary for the dehydrogenative coupling reaction between ethanol and acetaldehyde to produce ethyl acetate and the effective synthesis of methanol from CO2 and H2. In addition, we quantified the concentration of Cu and Cu-ZrO2 interfacial sites using a combination of sub-ambient CO Fourier transform infrared spectroscopy and reactive N2O chemisorption measurements. In Chapter 4, we prepared the supported Pt catalysts with different Mo contents by the CSR method for the reverse water gas shift (RWGS) reaction under dark and visible light illumination conditions. We demonstrated that Pt-MoOx interface formation and photoexcitation by visible light irradiation increase the catalytic activity for the RWGS reaction by alleviating CO poisoning on Pt surface. In Chapter 5, we showed that the deposition of Mo onto Au nanoparticles by the CSR method occurs preferentially on under-coordinated Au sites using reactivity measurements, CO FTIR studies, Raman spectroscopy, and X-ray absorption spectroscopy (XAS). Correlations of RWGS reactivity with changes in FTIR spectra for samples containing varying amounts of Mo indicate that interfacial sites are an order of magnitude more active than Au sites for RWGS under dark and visible light illumination conditions. In Chapter 6, we showed that the formation of Pt-FexOy interfaces by the CSR method increases the catalytic activity for the hydrogenation of carbonyl groups and CO oxidation. The presence of Pt-FexOy interfacial sites may enhance the catalytic activity by stabilization of the adsorbed reactive intermediates through bonding with C=O groups for carbonyl groups hydrogenation. The enhanced activity over Pt1Fex/SiO2 catalysts for CO oxidation compared to Pt/SiO2 can be associated with a lower energy barrier for O2 adsorption and activation over Pt-FexOy interfacial sites. We conclude with a discussion of future directions.
Surface Analysis of Cu/ZnO Catalysts for Methanol Synthesis - a Study on Nitrous Oxide Chemisorption and DRIFT Spectroscopy
Author: Samuel M. FehrCoal Abstracts
Author: Methanol Synthesis
Author: Jerzy SkrzypekPublisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 174
Book Description
Surface Organometallic Chemistry: Molecular Approaches to Surface Catalysis
Author: Jean-Marie BassetPublisher: Springer Science & Business Media
ISBN: 9400929714
Category : Science
Languages : en
Pages : 340
Book Description
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.