Rate equation Langmuir-Hinshelwood

The reader may verify that the scheme leads to the following Langmuir-Hinshelwood rate equation ... 

The plots are practically linear and show that the rates are constant. Consequently the order of reaction is zero at both initial pressures. If a Langmuir-Hinshelwood rate equation,... 

All constants of Langmuir-Hinshelwood rate equations are intrinsically positive so any mechanism that results in any negative constants is regarded as invalid. Although such a result may correlate the data adequately over the experimental range, extrapolation usually is not considered safe. 

The Langmuir—Hinshelwood rate equation (16) used by several authors for other types of catalyst was interpreted by Tanabe and Nitta [290] on the basis of their results with NiS04. The authors assume that the surface reaction of adsorbed ethylene and water molecules, which was found to be the slowest process, may be written in greater detail as... 

Steps 3-5 are strictly chemical and consecutive to each other Hougen-Watson-Langmuir-Hinshelwood rate equations describing the rate of the purely chemical phenomenon consisting of steps (3)-(5) have been derived in the chapter on the... 

Steps 3-5 are strictly chemical and consecutive to each other Hougen-Watson-Langmuir-Hinshelwood rate equations describing the rate of the purely chemical phenomenon consisting of steps 3-5 have been derived in Chapter 3 on the kinetics of catalysed reactions. In the transport-limited situation the supply of reactant and/or the removal of reaction product will not be sufficiently fast to keep pace with the potential intrinsic rate, and the concentrations of A and B inside the pores will be different from the corresponding concentrations in the bulk of the fluid phase. 

Doraiswamyf presented a very detailed review on the role of heterogeneous catalytic systems on inducing multiplicity and instability. In particular, this review focuses on the role that the Langmuir isotherm and the Langmuir-Hinshelwood rate equations (resulting... 

If the polymerization centers react with the adsorbed monomer molecules then the Langmuir-Hinshelwood rate equation [Eq. (P9.5.13)] should be used and one would obtain the rate expression in the stationary zone as... 

Problem 9.6 Show that under conditions where Km C [- 2] (see Table 9.5) the Langmuir-Hinshelwood rate equation becomes indistinguishable from the Rideal expression for the stationary zone rate. 

The double-line arrow indicates that catalyst decay is second order). The Langmuir-Hinshelwood rate equation, for control by the surface reaction and with q a(t) instead of q-r to account for progressing deactivation, is... 

The asymptotic effectiveness factor is a good approximation provided that the reaction order, with respect to the reactant, is positive, while a serious error can occur, if the reaction order is negative in which case the reaction is accelerated with decreasing reactant concentration. Similar dangerous kinetic expressions are also some Langmuir-Hinshelwood rate equations, in which the nominator is of a lower order than the denominator. For such reaction kinetics the effectiveness factor can, in extreme cases, exceed a value of 1. This can be intuitively understood the reaction rate increases due to the fact that the reactant concentration inside the particle becomes lower than in the bulk phase. Such cases are discussed in greater detail in the specific literature. 

Table 3.2 Some Examples of Langmuir-Hinshelwood Rate Equations... 

Kx,Kq absorption equilibrium constants in Langmuir-Hinshelwood rate equation, volume/mol... 

Even with an isothermal particle and without including the film, multiplicity is theoretically possible when the rate increases with conversion as may occur for some type of Langmuir-Hinshelwood rate equations and some particular parameter values. According to Luss the sufiknent condition for uniqueness of the concentration profile in the particle is ... 

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