Evaluation of sorbate/reactant shape-selectivity of zeolites by GC pulse techniques

Abstract

Rapid evaluation of sorbate/reactant shape-selectivity of medium-pore zeolites at operating conditions using isothermal and non-isothermal techniques (i.e., temperature-programmed desorption under Chromatographie conditions) has been described. The shape-selectivity of silicalite in sorption of sorbates having different critical sizes and configurations has been investigated at temperatures at which catalytic processes occur. The configuration and compressibility of bulkier sorbate molecules are much more important than critical molecular size in determining the shape-selective sorption/diffusion in medium-pore zeolites. GC pulse methods provide very simple and rapid means for studying molecular sieving and/or relative sorbate/reactant selectivity for bulkier sorbates undergoing configurational diffusion in the zeolites.