Effect of relative percentage of acid and base sites on the side-chain alkylation of toluene with methanol

K(3)PO(4)/NaX catalysts were prepared by loading potassium phosphate on NaX zeolite, and the catalytic performance was studied for the side-chain alkylation of toluene with methanol to styrene and ethylbenzene. Combined with the characterization of XRD, TPD-NH(3), TPD-CO(2), and FTIR and the determination of phosphorus content, it is revealed that firstly, the P element loaded on the catalyst surface can prominently promote the percentage of middle base sites, which will accordingly enhance the selectivity of the products (styrene and ethylbenzene) of side-chain alkylation of toluene; secondly, if there are enough middle base sites distributed on the catalysts, the higher percentage of strong base sites benefit the selectivity of styrene, which is confirmed by the performance of the two-stage catalysts.