Horiuti-Temkin theory

Chapter 2 describes the evolution in fundamental concepts of chemical kinetics (in particular, that of heterogeneous catalysis) and the "prehis-tory of the problem, i.e. the period before the construction of the formal kinetics apparatus. Data are presented concerning the ideal adsorbed layer model and the Horiuti-Temkin theory of steady-state reactions. In what follows (Chapter 3), an apparatus for the modern formal kinetics is represented. This is based on the qualitative theory of differential equations, linear algebra and graphs theory. Closed and open systems are discussed separately (as a rule, only for isothermal cases). We will draw the reader s attention to the two results of considerable importance. 

It means that we consider only mono-, bi- and (rarely) termolecular reactions. The coefficients stoichiometric coefficients and stoichiometric numbers observed in the Horiuti-Temkin theory of steady-state reactions. The latter indicate the number by which the elementary step must be multiplied so that the addition of steps involved in one mechanism will provide a stoichiometric (brutto) equation containing no intermediates (they have been discussed in Chap. 2). 

The most general description for the kinetics of complex reactions in terms of the ideal adsorbed layer model was given in the Horiuti-Temkin steady-state reaction theory [43-47] (see Chap. 1). 

Introduction of stoichiometric number concept and linear transformation of the "conventional" QSSA equations (16) to the equivalent system (20) was essentially the major (and, possibly, only) result of theory of steady reactions developed independently by J. Horiuti in 1950s and M. I. Temkin in 1960s. 

The application of the concept of "the rate along the basic route provides a possibility of obtaining a new formulation for the quasi-stationary conditions in terms of the Horiuti theory which is different from the ordinary one, i.e. "the formation of an intermediate is equal to that of its consumption . Temkin called the equations obtained "the conditions for the statio-narity of steps . In matrix form they are represented as... 

All his life, Temkin contributed to science in many areas, such as diffusion of heavy water into ordinary water, fugacity of gas mixtures, theory of mixtures of molten salts, and mass transfer in chemical engineering. But he left his indelible mark in the fundamentals of catalytic kinetics, on a par with C. J. Christiansen and J. Horiuti. 

That the theory of complex reactions kinetics went beyond LHHW treatment is due in major part to Horiuti and Temkin. Up to now it serves as a basis for mathematical modeling of catalytic processes and reactors at stationary conditions. The reaction and the process are considered to be stationary, if the concentration of all reactants and products in any element of the reactor space, including the active catalyst surface, do not change in time. At stationary conditions, concentrations of the intermediates are time independent as the rates of their generation in elementary steps are equal to the rates of consumption in other elementary reactions. 

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