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":"20 1","pages":"319-344"},"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":"41 1","pages":"253-318"},"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":"464 1","pages":"169-207"},"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}
Pub Date : 1997-08-01DOI: 10.1080/01614949709353777
G. Vayssilov
Abstract The review presents a comparison and discussion of the substantial amount of information about the state and coordination of titanium ions in titanium silicalites. The results from structural characterization of titanium silicalites with spectral, electrochemical, and quantum-chemical methods with emphasis on location of the Ti ions in framework or extraframework positions, their coordination, and the relationship of some spectral features to concrete structures at the atomic level are summarized. The main methods for the determination of some specific characteristics of titanium silicalite samples are considered—presence of metal ion impurities, extraframework titania, acidity, hydrophobicity, diffusion, and other sterical restrictions. Speculations on how these properties influence the catalytic activities and selectivities of the samples are discussed. Some experimental results for interaction of molecules—solvents, water, and hydrogen peroxide—with titanium silicalites are also presented. The...
{"title":"Structural and Physicochemical Features of Titanium Silicalites","authors":"G. Vayssilov","doi":"10.1080/01614949709353777","DOIUrl":"https://doi.org/10.1080/01614949709353777","url":null,"abstract":"Abstract The review presents a comparison and discussion of the substantial amount of information about the state and coordination of titanium ions in titanium silicalites. The results from structural characterization of titanium silicalites with spectral, electrochemical, and quantum-chemical methods with emphasis on location of the Ti ions in framework or extraframework positions, their coordination, and the relationship of some spectral features to concrete structures at the atomic level are summarized. The main methods for the determination of some specific characteristics of titanium silicalite samples are considered—presence of metal ion impurities, extraframework titania, acidity, hydrophobicity, diffusion, and other sterical restrictions. Speculations on how these properties influence the catalytic activities and selectivities of the samples are discussed. Some experimental results for interaction of molecules—solvents, water, and hydrogen peroxide—with titanium silicalites are also presented. The...","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":"17 1","pages":"209-251"},"PeriodicalIF":10.9,"publicationDate":"1997-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87127876","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 : 1997-02-01DOI: 10.1080/01614949708006468
F. Ribeiro, A. E. S. V. Wittenau, C. H. Bartholomew, G. Somorjai
Abstract The combination of turnover rate measurements and surface science techniques allows a firm quantification of rates in heterogeneous catalysis by metals. There are many examples of reactions where the turnover rates from different laboratories are the same. However, there are still problems, as in the isomerization and hydrogenolysis of hydrocarbons over noble metals, where the turnovers rates from different laboratories differ by many orders of magnitude. An explanation for this discrepancy is discussed. Guidelines for experimental work in heterogeneous catalysis that will help to minimize this wide scatter of turnover rates in the future are presented. ∗Current address: Department of Chemical Engineering, Worcester Polytechnic Institute, Worcerster, MA 01609-2280.
{"title":"Reproducibility of Turnover Rates in Heterogeneous Metal Catalysis: Compilation of Data and Guidelines for Data Analysis","authors":"F. Ribeiro, A. E. S. V. Wittenau, C. H. Bartholomew, G. Somorjai","doi":"10.1080/01614949708006468","DOIUrl":"https://doi.org/10.1080/01614949708006468","url":null,"abstract":"Abstract The combination of turnover rate measurements and surface science techniques allows a firm quantification of rates in heterogeneous catalysis by metals. There are many examples of reactions where the turnover rates from different laboratories are the same. However, there are still problems, as in the isomerization and hydrogenolysis of hydrocarbons over noble metals, where the turnovers rates from different laboratories differ by many orders of magnitude. An explanation for this discrepancy is discussed. Guidelines for experimental work in heterogeneous catalysis that will help to minimize this wide scatter of turnover rates in the future are presented. ∗Current address: Department of Chemical Engineering, Worcester Polytechnic Institute, Worcerster, MA 01609-2280.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":"38 1","pages":"49-76"},"PeriodicalIF":10.9,"publicationDate":"1997-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84534906","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 : 1997-02-01DOI: 10.1080/01614949708006467
P. Mériaudeau, C. Naccache
Abstract The direct catalytic conversion of alkanes into aromatics has found potentially important industrial applications. Initially only alkanes with 6 and more carbon atoms in the chain were concerned. Supported platinum catalysts were found active for the aromatization of alkanes; the drawbacks of these catalysts were their deactivation with time on stream and the existence of simultaneous parallel reactions. Much discussion has been published on the aromatization of C6+ alkanes. A bifunctional mechanism which involves both the metal and the acid sites of the support and a monofunctional mechanism involving only the metallic sites operate over, respectively, Pt supported on acidic support and Pt supported on nonacidic support. In the present review the mechanisms proposed for the aromatization of alkanes are described. Over monofunctional Pt catalysts two possible mechanisms prevail: 1,6 ring closure on the Pt surface involving primary and secondary C-H bond rupture, followed by dehydrogenation of the...
{"title":"Dehydrocyclization of Alkanes Over Zeolite-Supported Metal Catalysts: Monofunctional or Bifunctional Route","authors":"P. Mériaudeau, C. Naccache","doi":"10.1080/01614949708006467","DOIUrl":"https://doi.org/10.1080/01614949708006467","url":null,"abstract":"Abstract The direct catalytic conversion of alkanes into aromatics has found potentially important industrial applications. Initially only alkanes with 6 and more carbon atoms in the chain were concerned. Supported platinum catalysts were found active for the aromatization of alkanes; the drawbacks of these catalysts were their deactivation with time on stream and the existence of simultaneous parallel reactions. Much discussion has been published on the aromatization of C6+ alkanes. A bifunctional mechanism which involves both the metal and the acid sites of the support and a monofunctional mechanism involving only the metallic sites operate over, respectively, Pt supported on acidic support and Pt supported on nonacidic support. In the present review the mechanisms proposed for the aromatization of alkanes are described. Over monofunctional Pt catalysts two possible mechanisms prevail: 1,6 ring closure on the Pt surface involving primary and secondary C-H bond rupture, followed by dehydrogenation of the...","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":"1 1","pages":"5-48"},"PeriodicalIF":10.9,"publicationDate":"1997-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74923844","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 : 1997-01-01DOI: 10.1080/01614949708006469
PIETER L. J. Gunter, J. (Hans) Niemantsverdriet, FABIO H. Ribeiro, G. Somorjai
Abstract Nanoscale structural information underlies research aimed at fabricating catalysts in a more controlled way. Surface science methods can provide that information, but the complexity of heterogeneous systems in general hinders the application of these methods to their full potential. In the last decades, a solution to this problem has been found in the use of model systems, ranging from well-defined single crystals of the supported phase to films or particles of that phase on flat or spherical model supports. In this paper, we review the literature on the latter model systems, that is, particles on a model support. Attention is payed to both preparation and use of such model systems.
{"title":"Surface Science Approach to Modeling Supported Catalysts","authors":"PIETER L. J. Gunter, J. (Hans) Niemantsverdriet, FABIO H. Ribeiro, G. Somorjai","doi":"10.1080/01614949708006469","DOIUrl":"https://doi.org/10.1080/01614949708006469","url":null,"abstract":"Abstract Nanoscale structural information underlies research aimed at fabricating catalysts in a more controlled way. Surface science methods can provide that information, but the complexity of heterogeneous systems in general hinders the application of these methods to their full potential. In the last decades, a solution to this problem has been found in the use of model systems, ranging from well-defined single crystals of the supported phase to films or particles of that phase on flat or spherical model supports. In this paper, we review the literature on the latter model systems, that is, particles on a model support. Attention is payed to both preparation and use of such model systems.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":"2 1","pages":"77-168"},"PeriodicalIF":10.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89237393","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 : 1996-11-01DOI: 10.1080/01614949608006465
D. Barthomeuf
Abstract The presence of basic centers in some oxides has been recognized for a long time as being important in catalysis [1-4]. Usually both basic and acid sites exist simultaneously. The two centers may work independently or in a concerted way. For instance, in alcohol transformation, dehydration is favored on acidic sites and dehydrogenation on basic centers [3,5]. A large variety of materials are cited as having basic character. They include single-metal oxides (MgO, CaO, ZnO), supported alkali metals (Na/MgO, K/K2CO3), mixed-metal oxides (MgO-A12O3, ZnO-SiO2, MgO-TiO2), zeolites (X and Y saturated with alkaline cations of low electronegativity), hydrotalcite-type anionic clays, asbestoslike materials, carbon-supported basic catalysts, and basic organic resins. ∗ Present address: 16 rue Francois Gillet, 69003 Lyon, France.
{"title":"Basic zeolites : Characterization and uses in adsorption and catalysis","authors":"D. Barthomeuf","doi":"10.1080/01614949608006465","DOIUrl":"https://doi.org/10.1080/01614949608006465","url":null,"abstract":"Abstract The presence of basic centers in some oxides has been recognized for a long time as being important in catalysis [1-4]. Usually both basic and acid sites exist simultaneously. The two centers may work independently or in a concerted way. For instance, in alcohol transformation, dehydration is favored on acidic sites and dehydrogenation on basic centers [3,5]. A large variety of materials are cited as having basic character. They include single-metal oxides (MgO, CaO, ZnO), supported alkali metals (Na/MgO, K/K2CO3), mixed-metal oxides (MgO-A12O3, ZnO-SiO2, MgO-TiO2), zeolites (X and Y saturated with alkaline cations of low electronegativity), hydrotalcite-type anionic clays, asbestoslike materials, carbon-supported basic catalysts, and basic organic resins. ∗ Present address: 16 rue Francois Gillet, 69003 Lyon, France.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":"3 1","pages":"521-612"},"PeriodicalIF":10.9,"publicationDate":"1996-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78420107","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 : 1996-11-01DOI: 10.1080/01614949608006464
A. Trovarelli
Abstract Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a special focus towards catalyst interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide. Relevant catalytic and technological applications such as the use of ceria in automotive exhaust emission control and in the formulation of SO x reduction catalysts is described. A survey of the use of CeO2-containing materials as oxidation and reduction catalysts is also presented.
{"title":"Catalytic Properties of Ceria and CeO2-Containing Materials","authors":"A. Trovarelli","doi":"10.1080/01614949608006464","DOIUrl":"https://doi.org/10.1080/01614949608006464","url":null,"abstract":"Abstract Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a special focus towards catalyst interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide. Relevant catalytic and technological applications such as the use of ceria in automotive exhaust emission control and in the formulation of SO x reduction catalysts is described. A survey of the use of CeO2-containing materials as oxidation and reduction catalysts is also presented.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":"35 1","pages":"439-520"},"PeriodicalIF":10.9,"publicationDate":"1996-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87546993","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 : 1996-11-01DOI: 10.1080/01614949608006463
S. Albonetti, F. Cavani, F. Trifiró
Abstract This review examines some aspects in the development of heterogenous catalysts for the oxyfunctionalization of light paraffins. Particular attention is devoted to the raction of paraffin oxydehydrogenation to olefins and of n-butane oxidation to maleic anhydride. Most catalyst compositions are based on vanadium oxide as the main component, and the peculiar properties of this element with respect to the catalytic performance are discussed. These properties are also examined in ligh of the stability of the product of partial oxidation towards consecutive unselective oxidation reactions, and with respect to the mechanism of paraffin activation.
{"title":"Key Aspects of Catalyst Design for the Selective Oxidation of Paraffins","authors":"S. Albonetti, F. Cavani, F. Trifiró","doi":"10.1080/01614949608006463","DOIUrl":"https://doi.org/10.1080/01614949608006463","url":null,"abstract":"Abstract This review examines some aspects in the development of heterogenous catalysts for the oxyfunctionalization of light paraffins. Particular attention is devoted to the raction of paraffin oxydehydrogenation to olefins and of n-butane oxidation to maleic anhydride. Most catalyst compositions are based on vanadium oxide as the main component, and the peculiar properties of this element with respect to the catalytic performance are discussed. These properties are also examined in ligh of the stability of the product of partial oxidation towards consecutive unselective oxidation reactions, and with respect to the mechanism of paraffin activation.","PeriodicalId":50986,"journal":{"name":"Catalysis Reviews-Science and Engineering","volume":"8 1","pages":"413-438"},"PeriodicalIF":10.9,"publicationDate":"1996-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85692120","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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