DYNAMICS OF PROPENE METATHESIS - PHYSISORPTION AND DIFFUSION IN HETEROGENEOUS CATALYSIS

Simultaneous effects of physisorption, diffusion, and reaction were ch aracterized by dynamic experiments for propene metathesis over rhenium oxide/gamma-alumina catalyst in a Berty reactor. Single-component sor ption isotherms from steady-state experiments for ethene, propene, and 2-butene were used to predict multicomponent physisorption by the ide al adsorbed solution theory. Effective diffusivities were determined f rom molecular, Knudsen, and surface-diffusion coefficients, including bimodal pore-size effect and tortuosity factors. Transient sorption di ffusion experiments were conducted with inactivated catalysts. The rea ction rate expression, derived from elementary steps of carbene mechan ism, was identified by solving the inverse problem with step test data . The direct problem was solved by orthogonal collocation within the m ethod of lines. Model predictions agreed with responses from dynamic e xperiments carried out under conditions different from those used for estimating model parameters.