Dehydrogenation of Methylcyclohexane: Parametric Sensitivity of the Power Law Kinetics

Abstract

For heterogeneous catalytic reactions, the empirical power law model is a valuable tool that explains variation in the kinetic behavior with changes in operating conditions, and therefore aids in the development of an appropriate and robust kinetic model. In the present work, experiments are performed on 1.0 wt% Pt/Al2O3 catalyst over a wide range of experimental conditions and parametric sensitivity of the power law model to the kinetics of the dehydrogenation of methylcyclohexane is studied. Power law parameters such as order of the reaction, activation energy, and kinetic rate constants are found dependent upon the operating conditions. With H2 in the feed, both apparent order of the reaction and apparent activation energy generally increase with an increase in pressure. The results suggest a kinetic model, which involves nonlinear dependence of rate on the partial pressure of hydrogen and adsorption kinetics of toluene or some intermediate.

Review of fluid‐solid reaction analysis—Part 2: Single porous reactant solid

“…It is also noted that with all the advantages of the closed‐form solution that Sohn's law makes possible, such a solution is unable to accurately predict the rate at a low conversion value ( X < 0.1), as discussed in Szekely et al Although the analysis of reaction kinetics is often based on the initial rates, Sohn and Fan have shown that initial rates should not be relied upon to analyze a fluid‐solid reaction, especially for the reaction of a porous solid.…”

Review of fluid‐solid reaction analysis—Part 1: Single nonporous reactant solid

“…Often, researchers rely on the initial rate to obtain the kinetics information . This method may be applied to homogeneous reactions, but Sohn and Fan have shown that it is not appropriate for the analysis of a fluid‐solid reaction in general and in particular for a reaction affected by pore diffusion.…”

On the Initial Rate of Fluid–Solid Reactions

“…The ratio of the apparent activation energy for an intermediate value ofr 2 and the true activation energy should lie between one half and unity (for large or weakly temperature dependent K). This result is also observed in reactions in catalyst pellets [10] and also in the reactions of porous solids that produce no solid product layer.…”

“…The investigation of reaction kinetics often relies on the initial rates. [2][3][4][5][6] [Also see the numerous sources and sites found by googling with the term 'initial rate method.'] The initial rate method is appropriate for the determination of kinetics of homogeneous reactions, often saving time and effort.…”