Propane Aromatization on Zn-Modified Zeolite BEA Studied by Solid-State NMR in Situ

The conversion of propane (propane-1-C-13 and propane-2-C-13) on Zn/H-BEA zeolite at 520-620 K has been studied by H-1 and C-13 (CP) MAS NMR. Propene adsorption complex with zinc sites (pi-complex) and sigma-allylzinc species as intermediates have been identified in the course of propane conversion to aromatics. The mechanism leading to the formation of methane and ethane, which are constituents of an undesirable route in propane conversion, has been examined by kinetic modeling of the expected reaction network based on in situ H-1 MAS NMR kinetic measurements of the reaction performance. The pathways for propane aromatization and hydrogenolysis have been proposed. Hydrogenolysis of propane has been concluded to occur with the involvement of both Bronsted acid sites and Zn sites.