摘要:

The concept of structure sensitivity is well established for reactions catalyzed by metals as it has been generally demonstrated by the use of supported metal catalysts exhibiting different particle size [l-71. The con-cept of structure sensitivity in catalysis by metal oxides is considerably less well developed than in catalysis by metals, in spite of the growing number of examples of such reactions. Characterization of oxide catalyst is generally more problematical than that of metal; it is difficult, for example, to titrate the active surface areas of supported oxides by chemisorption techniques. Carboxylic acid decomposition could be used as a probe to establish struc-tural dependence and selectivity on metal oxides. For example, in the case of formic acid decomposition, bimolecular decomposition of two adsorbed formates occurs on a surface with Ti4+ cation of fourfold oxygen coordi-znation while unimolecular decomposition occurs in the case of formates adsorbed on Ti4+ fivefold coordinated cations [8]. Similarly, acetic acid adsorbed on Ti02 with Ti0,(011) leads to the production of ketene by unimolecular dehydration whereas on the Ti02(l 14) faceted surface, bi-molecular reaction of surface acetate takes place to form acetone [9, 101. Thus understanding the pathway of decomposition of carboxylic acid is likely not only to throw light on the new catalyst search for ketene formation but also to establish the use of this molecular decomposition model as a probe for the study of the structural property of metal oxide catalysts.

ISSN:0161-4940    

DOI:10.1080/01614949408009466

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The importance of fluid catalytic cracking of hydrocarbons (FCC) as a leading process in the chemical industry has been acknowledged for a long time. Present data on feedstock processing and its overall economical impact confirm such a role [1, 21. Technical, economic, and environmental concerns have played significant roles as driving forces in the research conducted on FCC matters, leading to developments that are identifiable along catalytic cracking chronology (e.g., fluid bed technology, zeolite catalyst introduction, promotor addition, octane boosting).

ISSN:0161-4940    

DOI:10.1080/01614949408009467

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The catalytic treatment of motor vehicle exhaust gas has been a feature of all passenger cars in the USA since the 1975 model year. It has since been adopted in all the developed countries as the principal means of con-trolling the emissions from vehicles powered by Otto-cycle internal com-bustion engines. These include passenger cars, light trucks, and heavy-duty trucks. Catalysts have been developed for motorcycles and even smaller power plants. The so-called three-way catalyst (TWC) has been in use since the 1979 model year. The name reflects the simultaneous treatment by this catalyst of the two reducing pollutants, carbon monoxide and uncombusted hydrocarbons, and the oxidizing pollutant, oxides of nitrogen.

ISSN:0161-4940    

DOI:10.1080/01614949408009468

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Primary or alkylated amines are important chemicals and intermedi-ates. N-Alkylamines are used without further transformation as surface-active agents. Aliphatic primary diamines polymerize with aliphatic diacids to give linear polyamides which have conquered a large place in textile and mechanical industry [11. Mono- and polyamines are produced by catalytic hydrogenation of the corresponding nitriles [2]. In particular this pathway to hexamethylenediamine has been made easier since the synthesis of adi-ponitrile by hydrocyanation of butadiene was made possible [3]. The spec-ifications for production of amines are often very drastic from the point of view of purity, in particular for the diamines used in the textile industry. Thus the stress is put on selectivity of the reaction and most of industrial processes have a yield approaching stoichiometry. It exists few reviews on reduction of nitriles [4, 51, the literature dealing with this type of reaction being mostly published in patents [6–91, and practical knowledge is at the state of “know-how” [lo]. Up to now, two types of processes have been used industrially for the

ISSN:0161-4940    

DOI:10.1080/01614949408009469

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The oxidative coupling of methane (OCM) to higher hydrocarbons may eventually become an interesting alternative for the chemical utilization of natural gas. Extensive studies have been conducted since the works of Keller and Bhasin [l] and of Hinsen and Baerns [2].

ISSN:0161-4940    

DOI:10.1080/01614949408009470

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor