Shape selective methylation of 4-methylbiphenyl with methanol over MgO/HZSM5

The effects of catalyst activation and the reaction conditions on the methylation of 4-methylbiphenyl (4-MBP) with methanol over MgO/CBV8020 were investigated. With an increase in the reaction temperature, the conversion of 4-MBP decreased and the selectivity to 4,4′-dimethylbiphenyl (4,4′-DMBP) first increased, then decreased. With an increase in the reaction temperature, the isomerization of 4-MBP into 3-MBP increased, as well as the isomerization of 4,4′-DMBP into 2,3′- and 3,4′-DMBP. The effect of reaction time on the methylation of 4-MBP with methanol showed that both the conversion of 4-MBP and the selectivity to 4,4′-DMBP decreased with reaction time. Moreover, the addition of water in the feed did not favor methylation of 4-MBP with methanol. With an increase in the amount of mesitylene, both the selectivity to 4,4′-DMBP and 4-MBP conversion increased a little. However, the activity stability improved a lot, after 375 min reaction, the selectivity to 4,4′-DMBP was ∼ 80%, and 4-MBP conversion was ∼ 8%.