High-efficiency toluene alkylation with tert-butyl alcohol catalyzed by Ce2O3-modified H-beta zeolites

A series of xCe2O3/H-beta catalysts with different Ce2O3 loadings were prepared and the catalytic performances were investigated through toluene butylation as the probe reaction. The xCe2O3/H-beta catalysts showed high para-selectivity due to their improved structural and acidic properties, which were confirmed by XRD, SEM, ICP-OES, BET, Py-IR and TG. Compared with the parent H-beta zeolite, the xCe2O3/H-beta catalysts showed slightly lower toluene conversion and significantly higher para-tert-butyl toluene (PTBT) selectivity. Loading of Ce2O3 firstly narrowed the pore size of H-beta zeolite, which benefited the shape-selectivity, and secondly increased the PTBT selectivity by suppressing the isomerization on acid sites of outer surface of the catalysts. Under comparable conditions, the 5%Ce2O3/H-beta exhibited the maximum PTBT selectivity (82.7%) at 180 °C after 4 h. The optimum reaction conditions over xCe2O3/H-beta zeolites were molar ratio of tert-butyl alcohol to toluene = 3:1, reaction temperature = 180 °C, and reaction time = 4 h.