Synergistic effects of dehydrogenation component Cu and medium base on side chain alkylation of toluene with methanol

Activation of hydrogen atoms of methyl in toluene and methanol is crucial for side-chain alkylation of toluene with methanol. Herein, two strategies were applied, introducing dehydrogenation component (Cu) and tailoring the catalyst acid-base property with NaOH. A series of Cu and NaOH dual-modified PAl-NaX catalysts were prepared by in-situ hydrothermal method, the synergistic effect of Cu and NaOH was investigated. It is revealed that the product of (medium base)* (weak acid) and surface Cu δ+ percentage is crucial in controlling the total yield of side chain alkylation products by enhancing ethyl benzene selectivity. Cat-3Cu-13Na exhibits the optimal catalytic performance with an average methanol conversion of 97.25 % and an average total yield of side chain alkylation products of 77.46 % without obvious deactivation occurs in 192 h, and Cat-3Cu-19Na shows a promising styrene selectivity of 44.06 %. The decrease of weak acid sites might result in the decline in selectivity of styrene.