Heterogeneous Acid-Base Catalysis

E.A. Paukshtis, Infra-red spectroscopy in heterogeneous acid-base catalysis, Novosibirsk, Nauka, 1992. 

Catalog of Teratogenic Agents, 25 209 Catalysis 5 200-254. See also Acid-base catalysis Catalyst entries Catalytic entries Heterogeneous catalysis Homogeneous catalysis Photocatalysis of aromatic reactions, 16 844 cerium applications, 5 685-688... 

In heterogeneous catalysis we distinguish usually two mechanisms—the acid-base catalysis, which may be of the same type as the amino acid catalysis, and the catalysis by semiconductors and metals. The theory of this last type of catalysis was developed by T. T. Volkenstein in the U.S.S.R., by Germain in France, and by other scientists in Germany and in the United States. This theory is related to what you have indicated for MgO. It is assumed that an electron deficiency or electron excess is introduced as an impurity that creates, ultimately on the surface, a defect that can bind quasi-chemically electron donors or electron acceptors, respectively. 

However, simple kinetic models, especially of the Langmuir—Hinshel-wood type, can serve with advantage for correlation of experimental data in spite of simplifying assumptions which are necessary for their derivation. Experience shows that heterogeneous acid—base catalysis is the very field where they fit best. Their most frequent general form... 

The three themes of the symposium selective hydrogenation, selective oxidation and acid-base catalysis were introduced by four plenary lectures and two invited communications. A panel concerned with the future of zeolites and other shape-selective materials for fine chemical synthesis was conducted by specialists in the field D. Barthomeuf (University of Paris 6), E. Derouane (University of Namur), L. Forni (University of Milan), M. Gubelmann (Rhone-Poulenc, St Fons), W. Hoelderich (BASF, Ludwigshafen) and G. Perot (University of Poitiers). An exhibition of equipment was held during the symposium on October 3 and 4. Over 20 firms exhibited equipment, chemicals and catalysts which were of interest to researchers involved with the synthesis of functional compounds by heterogeneous catalysis. 

Paukschtis, Evgenii, Infrared Spectroscopy in Heterogeneous Acid-Base Catalysis. Novosibirsk Nauka, 1992. 

Kinetic investigations have shown that during heterogeneous catalysis performed with metal oxides the associated acid site (metal cation) can also activate the carbonyl group, leading to cooperative acid-base catalysis. With organic bases attached to a mineral support such an effect would not be so pronounced. 

These proceedings from the 19 th Conference represent the work of over 150 scientists from fourteen countries. The proceedings are organized into the following topics immobilized and supported catalysts, practical aspects of catalysis, solid acid and base catalysis, heterogeneous catalysis and commercial processes, Raney-type and base metal catalysis, stereoselective catalysis, and hydrogenation and amination. 

Table 2 states that around 7 % natural gas and 7 % crude oil are used to produce so-called primary chemicals. Apart from heterogeneous catalysis and acid-base catalysis processes, two main GPTRs transform raw material into primary chemicals (Table 4a). 

Compared with the number of industrial processes using heterogeneous or acid-base catalysis, the number of processes involving GPTRs appears to be relatively small. This is due to several reasons ... 

Paukshtis, E.A., Yurchenko, E.N. (1983). Study of the Acid-Base Properties of Heterogeneous Catalysts by Infrared Spectroscopy. Russian Chemical Reviews, Vol.52, No.3, (March 1983), pp. 242-258, ISSN 0036-021X Paukshtis, E. A. (1992). Infrared Spectroscopy of Heterogeneous Acid-Base Catalysis (in Russian), Nauka, ISBN 5-02-029281-8, Novosibirsk... 

In the catalytic sciences, and specifically in the context of organic synthesis, it is common to represent the catalytic transformation of reactants, namely, reagents (substrate(s)) to product(s) as shown in Fig. la. This simplified representation puts emphasis on the net transformation of reactants, which is indeed the proper emphasis for the vast majority of synthetic situations. In Fig. la, the details of the catalysis are embedded in the term [cat], and the details are in no maiuier explicit. Therefore, in fine heterogeneous catalysis [cat] is simply understood to be a heterogeneous catalyst, perhaps a supported metal added to the system [1], in enzymatic catalysis [cat] is usually understood to be a protein or metaUoprotein added to the system [2], in organocatalysis [cat] is often understood to be an organic amine or phosphine added to the system [3], in acid/base catalysis [cat] may refer to or OH in the system or... 

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