Effect of different frameworks on the zeolite catalyzed alkylation of benzene with 1-dodecene

Abstract

Structure-reactivity relationship acts as a hot topic in the zeolite catalyzed reactions for a long time. Herein, Beta and MCM-49 with two representative frameworks are selected to elucidate this concept, attempting to reveal the essential difference in their catalytic performance for the alkylation of benzene with 1-dodecene from both experimental and theoretical aspects. It is revealed that the effective acid sites for the alkylation of benzene with 1-dodecene over MCM-49 are mainly located at the 12 MR (membered-ring) cups, wherein the reactants and products can diffuse with less restriction. Therefore, MCM-49 exhibits higher lifetime and selectivity although the 12 MR supercage and 10 MR sinusoidal channels possessing shape-selectivity contribute little to this reaction, which has also been further evidenced by the density functional theory (DFT) calculation results. The low lifetime and selectivity observed over Beta are mainly assigned to the strong accommodation and slow diffusion of reactants and products within its long channels, and decreasing crystal size or constructing hierarchical framework have been further demonstrated to be effective to alleviate its deactivation.