Catalytic kinetics in nanoconfined space of acidic micro/mesoporous materials

Abstract

Kinetics of heterogeneous acid catalyzed reactions is considered for micro-mesoporous materials taking into account nonuniformity of active sites, located in different pores. The methodology for deriving rate equations is developed accounting for reactions in single site nanopores, in macropores/external surfaces of crystals, in narrow nanopores with Gemini sites, as well as in more wider nanoconfined pores with limited pore occupancy. Contribution of such nanoconfined pores was considered using the acid site density as a kinetic descriptor for activity and selectivity. The rate equation wasderived for a mechanism with two kinetically significant steps,assuming thatthethe intermediate sizepores accommodateonly two molecules.The kinetic treatment accounts for different reactivity of acid sites and lateral interactions.Modification of zeolites to form mesopores was discussed from the kinetic viewpoint highlighting how such treatment influences activity and selectivity.Finally, the reactant and product shape selectivity is discussed in a quantitative way.