Pub Date : 1998-08-01DOI: 10.1080/01614949808007110
B. Wojciechowski
Abstract Catalytic cracking has reached technological maturity without the benefit of a fundamental understanding and quantification of its elementary processes. Without this understanding, advances in this field have become increasingly rare and will be even more difficult to achieve in the future. This article offers a basis for the development of a fundamental understanding of catalytic cracking. It ties together all of the principal phenomena in catalytic cracking and lays a foundation for their quantification on the basis of the following postulates. 1. All important processes involved in the suite of reactions which fall under the generic name of “catalytic cracking” proceed via the mediation of surface-resident ions. 2. These ions undergo only two types of reactions and produce all the major gas-phase products: (a) Bimolecular disproportionations with neutral gas-phase molecules, or with neutral portions of neighboring carbenium ions, via the formation of pentacoordinated carbonium ion intermediate...
{"title":"The Reaction Mechanism of Catalytic Cracking: Quantifying Activity, Selectivity, and Catalyst Decay","authors":"B. Wojciechowski","doi":"10.1080/01614949808007110","DOIUrl":"https://doi.org/10.1080/01614949808007110","url":null,"abstract":"Abstract Catalytic cracking has reached technological maturity without the benefit of a fundamental understanding and quantification of its elementary processes. Without this understanding, advances in this field have become increasingly rare and will be even more difficult to achieve in the future. This article offers a basis for the development of a fundamental understanding of catalytic cracking. It ties together all of the principal phenomena in catalytic cracking and lays a foundation for their quantification on the basis of the following postulates. 1. All important processes involved in the suite of reactions which fall under the generic name of “catalytic cracking” proceed via the mediation of surface-resident ions. 2. These ions undergo only two types of reactions and produce all the major gas-phase products: (a) Bimolecular disproportionations with neutral gas-phase molecules, or with neutral portions of neighboring carbenium ions, via the formation of pentacoordinated carbonium ion intermediate...","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1998-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87490384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-01DOI: 10.1080/01614949808007106
P. Gallezot, D. Richard
Abstract The synthesis of a large number of fine chemicals, particularly in the field of flavor and fragrance chemistry [1,2] and pharmaceuticals [3], involves the selective hydrogenation of unsaturated carbonyl intermediates as a critical step. The hydrogenation of α,β-unsaturated carbonyls into saturated carbonyls is comparatively easy to achieve because thermodynamics favor the hydro-genation of the C═C bonds; therefore, research efforts were more directed at improving the selectivity to unsaturated alcohols. When a substituent is present on the carbon atom of the carbonyl group (i.e. with ketones), there is no chance to hydrogenate selectively the C═O bond, and saturated ketones are obtained with a high yield. This review is thus mostly restricted to the hydrogenation of α, β-unsaturated aldehydes into the corresponding unsaturated alcohols.
{"title":"Selective Hydrogenation of a,-Unsaturated Aldehydes","authors":"P. Gallezot, D. Richard","doi":"10.1080/01614949808007106","DOIUrl":"https://doi.org/10.1080/01614949808007106","url":null,"abstract":"Abstract The synthesis of a large number of fine chemicals, particularly in the field of flavor and fragrance chemistry [1,2] and pharmaceuticals [3], involves the selective hydrogenation of unsaturated carbonyl intermediates as a critical step. The hydrogenation of α,β-unsaturated carbonyls into saturated carbonyls is comparatively easy to achieve because thermodynamics favor the hydro-genation of the C═C bonds; therefore, research efforts were more directed at improving the selectivity to unsaturated alcohols. When a substituent is present on the carbon atom of the carbonyl group (i.e. with ketones), there is no chance to hydrogenate selectively the C═O bond, and saturated ketones are obtained with a high yield. This review is thus mostly restricted to the hydrogenation of α, β-unsaturated aldehydes into the corresponding unsaturated alcohols.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1998-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73782554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-01DOI: 10.1080/01614949808007105
W. Cheng, G. Kim, A. W. Peters, X. Zhao, K. Rajagopalan, M. Ziebarth, C. Pereira
The fluid catalytic cracking (FCC) process converts heavy oil into voluable fuel products and petrochemical feedstocks. Environmental regulations are a key driving force for reducing FCC process ai...
{"title":"Environmental Fluid Catalytic Cracking Technology","authors":"W. Cheng, G. Kim, A. W. Peters, X. Zhao, K. Rajagopalan, M. Ziebarth, C. Pereira","doi":"10.1080/01614949808007105","DOIUrl":"https://doi.org/10.1080/01614949808007105","url":null,"abstract":"The fluid catalytic cracking (FCC) process converts heavy oil into voluable fuel products and petrochemical feedstocks. Environmental regulations are a key driving force for reducing FCC process ai...","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1998-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79336507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-01DOI: 10.1080/01614949808007108
G. Centi, S. Perathoner
Abstract Heterogeneous catalysis plays a central role in most chemical reactions of industrial importance [1], but new advanced catalysts (superselective, able to transform new feedstocks and to synthesize new products, etc.) are required to comply with the future energy, safety, health, and environmental needs of the chemical industry [2]. The design of these new catalytic materials requires further understanding of the surface processes determining the catalytic transformations [3].
{"title":"The Role of Ammonia Adspecies on the Pathways of Catalytic Transformation at Mixed Metal Oxide Surfaces","authors":"G. Centi, S. Perathoner","doi":"10.1080/01614949808007108","DOIUrl":"https://doi.org/10.1080/01614949808007108","url":null,"abstract":"Abstract Heterogeneous catalysis plays a central role in most chemical reactions of industrial importance [1], but new advanced catalysts (superselective, able to transform new feedstocks and to synthesize new products, etc.) are required to comply with the future energy, safety, health, and environmental needs of the chemical industry [2]. The design of these new catalytic materials requires further understanding of the surface processes determining the catalytic transformations [3].","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1998-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81286797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-01DOI: 10.1080/01614949808007107
M. Bonn, H. Bakker, K. Domen, C. Hirose, A. Kleyn, R. V. van Santen
Abstract The application of (picosecond) nonlinear infrared spectroscopy to investigate zeolite catalysts and adsorbates is reviewed. In these time-resolved experiments, one specific vibration in the zeolite system (i.e., a zeolite or adsorbate vibration) is selectively excited with an ultrashort (tunable) mid-infrared pulse. The effect of this excitation and the subsequent energy relaxation can be monitored real time, providing information on the structure of the bare zeolite and adsorption complexes. More importantly, with this technique the picosecond energy flow at the catalytic site and the dynamics of the catalyst-adsorbate interaction can be investigated: Short-lived transient species (e.g., reaction intermediates) are observed and the picosecond relaxation rates and pathways at the catalytic site render insights into the dynamics of the interaction between the zeolite catalyst and its adsorbates at a molecular level. This illustrates the potential of time-resolved infrared spectroscopy in the inve...
{"title":"Dynamical studies of zeolitic protons and adsorbates by picosecond infrared spectroscopy","authors":"M. Bonn, H. Bakker, K. Domen, C. Hirose, A. Kleyn, R. V. van Santen","doi":"10.1080/01614949808007107","DOIUrl":"https://doi.org/10.1080/01614949808007107","url":null,"abstract":"Abstract The application of (picosecond) nonlinear infrared spectroscopy to investigate zeolite catalysts and adsorbates is reviewed. In these time-resolved experiments, one specific vibration in the zeolite system (i.e., a zeolite or adsorbate vibration) is selectively excited with an ultrashort (tunable) mid-infrared pulse. The effect of this excitation and the subsequent energy relaxation can be monitored real time, providing information on the structure of the bare zeolite and adsorption complexes. More importantly, with this technique the picosecond energy flow at the catalytic site and the dynamics of the catalyst-adsorbate interaction can be investigated: Short-lived transient species (e.g., reaction intermediates) are observed and the picosecond relaxation rates and pathways at the catalytic site render insights into the dynamics of the interaction between the zeolite catalyst and its adsorbates at a molecular level. This illustrates the potential of time-resolved infrared spectroscopy in the inve...","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1998-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83018956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-01DOI: 10.1080/01614949808007104
J. Millet
Abstract This review presents the iron phosphorus oxides used as catalysts for isobutyric acid oxidative dehydrogenation. Research on this catalytic system has been developed in the last decade and many publications have been devoted to this reaction, as it can be a step in a new process of production of methyl methacrylate. We emphasize particularly the nature of the active phase, the active centers, and the role of water and promoters. The mechanistic aspects of the reaction, which corresponds to an extension of the Mars and van Krevelen mechanism with a special role of water partial pressure, are discussed.
{"title":"FePO Catalysts for the Selective Oxidative Dehydrogenation of Isobutyric Acid into Methacrylic Acid","authors":"J. Millet","doi":"10.1080/01614949808007104","DOIUrl":"https://doi.org/10.1080/01614949808007104","url":null,"abstract":"Abstract This review presents the iron phosphorus oxides used as catalysts for isobutyric acid oxidative dehydrogenation. Research on this catalytic system has been developed in the last decade and many publications have been devoted to this reaction, as it can be a step in a new process of production of methyl methacrylate. We emphasize particularly the nature of the active phase, the active centers, and the role of water and promoters. The mechanistic aspects of the reaction, which corresponds to an extension of the Mars and van Krevelen mechanism with a special role of water partial pressure, are discussed.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1998-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80053193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-01DOI: 10.1080/01614949708007100
M. Hunger
Abstract Nearly all atoms contributing to the local structure of Br⊘nsted acid sites in zeolites exhibit isotopes accessible for multinuclear solid-state nuclear magnetic resonance (NMR) investigations. Therefore, in the last 15 years, NMR spectroscopy has found numerous applications for the determination of the types of hydroxyl proton in zeolites, of their concentration, accessibility, and mobility, and for the characterization of their acid strength and local structure. It allows the study of the role of hydroxyl groups in the formation of adsorbate complexes and in heterogeneously catalyzed reactions. Meanwhile, NMR spectroscopy belongs to the most powerful techniques for the characterization of Br⊘nsted acid sites in zeolites and related materials. The basis of this success is the invention of new sample preparation techniques, external magnetic fields with high-flux densities, effective line-narrowing methods, and new two-dimensional experiments, making the detection of highly resolved solid-state N...
{"title":"Br⊘nsted Acid Sites in Zeolites Characterized by Multinuclear Solid-State NMR Spectroscopy","authors":"M. Hunger","doi":"10.1080/01614949708007100","DOIUrl":"https://doi.org/10.1080/01614949708007100","url":null,"abstract":"Abstract Nearly all atoms contributing to the local structure of Br⊘nsted acid sites in zeolites exhibit isotopes accessible for multinuclear solid-state nuclear magnetic resonance (NMR) investigations. Therefore, in the last 15 years, NMR spectroscopy has found numerous applications for the determination of the types of hydroxyl proton in zeolites, of their concentration, accessibility, and mobility, and for the characterization of their acid strength and local structure. It allows the study of the role of hydroxyl groups in the formation of adsorbate complexes and in heterogeneously catalyzed reactions. Meanwhile, NMR spectroscopy belongs to the most powerful techniques for the characterization of Br⊘nsted acid sites in zeolites and related materials. The basis of this success is the invention of new sample preparation techniques, external magnetic fields with high-flux densities, effective line-narrowing methods, and new two-dimensional experiments, making the detection of highly resolved solid-state N...","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85675304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-01DOI: 10.1080/01614949708007099
J. Houžvička, V. Ponec
Abstract In this review, the most relevant aspects of skeletal isomerization of n-butene to isobutene are discussed: the nature of the active sites, the prevailing mechanism of the skeletal isomerization, and the relation of this to that of n-butane. It is concluded that the prevailing mechanism of skeletal isomerization of n-butene is monomolecular (in contrast to butane isomerization) and requires Br⊘nsted acid (OH) active sites. The selectivity and catalytic stability can be influenced by the shape selectivity of zeolites and zeotypes. These effects are explained on the basis of the knowledge on the prevailing mechanism.
{"title":"Skeletal Isomerization of n-Butene","authors":"J. Houžvička, V. Ponec","doi":"10.1080/01614949708007099","DOIUrl":"https://doi.org/10.1080/01614949708007099","url":null,"abstract":"Abstract In this review, the most relevant aspects of skeletal isomerization of n-butene to isobutene are discussed: the nature of the active sites, the prevailing mechanism of the skeletal isomerization, and the relation of this to that of n-butane. It is concluded that the prevailing mechanism of skeletal isomerization of n-butene is monomolecular (in contrast to butane isomerization) and requires Br⊘nsted acid (OH) active sites. The selectivity and catalytic stability can be influenced by the shape selectivity of zeolites and zeotypes. These effects are explained on the basis of the knowledge on the prevailing mechanism.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81951691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-08-01DOI: 10.1080/01614949709353778
J. Veldsink, M. Bouma, N. Schöön, A. Beenackers
Abstract Hardening of vegetable oils is reviewed from an engineering point of view. The present review focuses on kinetics of the hydrogenation and relevant transport and adsorption steps. It aims to contribute to accelerate new research to improve substantially on selectivities in general and a decrease of trans fatty acid content in particular. From a comprehensive literature review, we concluded the absence of reliable, mechanistically based kinetic rate expression. Moreover, transport limitations, both intraparticle and interfacial, cannot be excluded from the vast majority of available experimental data. Therefore, future research should focus on the development of intrinsic kinetic rate expressions, which may subsequently contribute to develop new and improved hydrogenation catalysts.
{"title":"Heterogeneous hydrogenation of vegetable oils: A literature review","authors":"J. Veldsink, M. Bouma, N. Schöön, A. Beenackers","doi":"10.1080/01614949709353778","DOIUrl":"https://doi.org/10.1080/01614949709353778","url":null,"abstract":"Abstract Hardening of vegetable oils is reviewed from an engineering point of view. The present review focuses on kinetics of the hydrogenation and relevant transport and adsorption steps. It aims to contribute to accelerate new research to improve substantially on selectivities in general and a decrease of trans fatty acid content in particular. From a comprehensive literature review, we concluded the absence of reliable, mechanistically based kinetic rate expression. Moreover, transport limitations, both intraparticle and interfacial, cannot be excluded from the vast majority of available experimental data. Therefore, future research should focus on the development of intrinsic kinetic rate expressions, which may subsequently contribute to develop new and improved hydrogenation catalysts.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1997-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85581616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-08-01DOI: 10.1080/01614949709353776
C. R. Dias, M. Portela, G. Bond
Abstract Information concerning the oxidation of o-xylene and naphthalene, the two main processes for producing phthalic anhydride, is updated and analyzed. New techniques for the preparation of catalysts, all based in the impregnation method and involving the control of parameters such as pH and ionic strength of solutions, are described; the performance of the resulting catalysts is compared with that of catalysts prepared by other methods. Sulfur-containing substances and promoters such as Ag, P, Nb, and Sb have been shown to enhance catalyst performance; studies of their effect on the surface area, acidic properties, and stabilization of the oxidation state of vanadium in supported V2O5 catalysts are described. The latest attempts to correlate the physicochemical characteristics of the catalysts with their catalytic features are analyzed. FTIR, Raman spectroscopy, adsorption of bases, 51V-NMR, XRD, XPS, SIMS, and electrical conductivity have been used in the study of V2O5/TiO2 catalysts, allowing furt...
{"title":"Synthesis of Phthalic Anhydride: Catalysts, Kinetics, and Reaction Modeling","authors":"C. R. Dias, M. Portela, G. Bond","doi":"10.1080/01614949709353776","DOIUrl":"https://doi.org/10.1080/01614949709353776","url":null,"abstract":"Abstract Information concerning the oxidation of o-xylene and naphthalene, the two main processes for producing phthalic anhydride, is updated and analyzed. New techniques for the preparation of catalysts, all based in the impregnation method and involving the control of parameters such as pH and ionic strength of solutions, are described; the performance of the resulting catalysts is compared with that of catalysts prepared by other methods. Sulfur-containing substances and promoters such as Ag, P, Nb, and Sb have been shown to enhance catalyst performance; studies of their effect on the surface area, acidic properties, and stabilization of the oxidation state of vanadium in supported V2O5 catalysts are described. The latest attempts to correlate the physicochemical characteristics of the catalysts with their catalytic features are analyzed. FTIR, Raman spectroscopy, adsorption of bases, 51V-NMR, XRD, XPS, SIMS, and electrical conductivity have been used in the study of V2O5/TiO2 catalysts, allowing furt...","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":null,"pages":null},"PeriodicalIF":10.9,"publicationDate":"1997-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75837438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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