Abstract
A feasible, comprehensive, and rigorous mechanistic kinetic model was developed for hydrogenolysis of thiophene on a commercial hydrodesulphurization Co-Mo/γ-Al2O3 catalyst. The kinetics were modeled with 24 rate expressions based on three modes of adsorption: molecular and atomic adsorption of hydrogen, and Eley Rideal mechanism. The experimental data were obtained in a bench-scale tubular reactor with plug flow, and the conditions varied over the following range: total pressure, P t = 2–30 bar, temperature = 533–625 K, and molar hydrogen to hydrocarbon ratios 4–9. The experimental rate data were described by a set of Lagmuir-Hinshelwood-Hougen-Watson rate equations for both the hydrogenolysis of thiophene to butene and the hydrogenation of butene to butane on two different sites, σ and τ. The kinetic rate constants and adsorption equilibrium constants were estimated for each model using the optimization routine of Nelder-Mead simplex algorithm. Discrimination among rival models was based upon physicochemical criteria, analysis of the residuals, and statistical tests. The surface reaction between adsorbed thiophene and adsorbed hydrogen on σ sites in the hydrogenolysis, and the surface reaction between adsorbed butene and adsorbed hydrogen on τ sites in the hydrogenation when hydrogen is adsorbed molecularly are found to be the rate-determining steps. The predicted activation energies, enthalpies of adsorption, Gibbs free energies, and adsorption entropies compare exceedingly well with previously reported values in the literature.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have