Twigg mechanism

The first mechanistic concepts of aromatization 16) originate from pregas-chromatography times. A direct alkane- cycloalkane reaction was proposed by Kazansky and co-workers 47). Several authors have interpreted the formation of six-membered rings over metal catalysts in terms of alkene-alkyl insertion (i.e., analogous to the Twigg mechanism) (7, 8, 14). 

An interesting example for which eqn. (169) is valid, but the mechanism has an interaction step of various intermediates, is ethylene hydrogenation on nickel, i.e. the Twigg mechanism [54]... 

Systems (1) enter into class 3 (a PDE point is a PCB). Systems with linear reaction mechanisms belong to both class (2) and class (3) but these classes do not overlap since there are systems without intermediate interactions that do not satisfy the principle of complex balance (e.g. the Eley-Rideal mechanism for CO oxidation on platinum metal). On the other hand, there exist reaction mechanisms containing steps of "intermediate interactions but at the same time always having a PCB (e.g. the Twigg mechanism for ethylene hydrogenation on nickel). 

M. V. Twigg, Mechanisms of Inorganic and Organometallic Reactions, Plenum Press, New York, 1983, p. 39. 

Twigg, M. V (Ed.) Mechanisms of Inorganic Organometallic Reactions Plenum Press New York, 1986 Vol. 4. 

House, D. A. In Mechanisms of Inorganic and Organometallic Reactions Twigg, M. V., Ed. Plenum Press New York Vol. 8, Ch. 6,1994,97 see also earlier volumes in this series. 

Transient deposition of hydrocarbons on zeolites during a cold start operation of the DOC can be modeled by the rate laws based on Langmuir or Temkin mechanism for physical adsorption/desorption (cf., e.g. Goralski et al., 2000 Koltsakis and Stamatelos, 2000 Kruglov and Aris, 1995 Kryl et al., 2005 Twigg, 2006). The rate laws for the adsorption and desorption of hydrocarbons are then... 

The first thorough investigation of the mechanism of ethylene oxidation on silver surfaces was undertaken by Twigg,1171 who passed a mixture of air and ethylene at 200-350° over fine glasB wool ooated with metallic silver and obtained ethylene oxide, carbon dioxide, and water vapor. The reaction appeared to oonsist of two independent overall processes, which could be depicted separately as shown in Eq. (09) and (100). Of the two reactants, only oxygen was actually o... 

Apart from kinetic measurements, the studies of oxygen adsorption on silver (63, 64), electron work function variations accompanying oxygen adsorption (65-67), heat effects of adsorption (65), reactivity of oxygen adsorbed on silver (67), and oxygen isotopic exchange on silver (56-55) were used for the elucidation of the mechanism of the reaction. The papers cited contain references to the works of other authors that were used for the formulation of the reaction mechanism on a level with our results. Here we shall mention, first of all, the work by Twigg (69), who has ascertained... 

The epoxidation of ethylene on silver is an important industrial process in which the practical yield is lower than 20%, with a selectivity of about 80%. It is remarkable that only Ag selectively catalyzes this reaction. The mechanism of epoxidation originally proposed by Twigg [49] for this reaction can be written as... 

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