Cerium promoted V-g-C(3)N(4) as highly efficient heterogeneous catalysts for the direct benzene hydroxylation

A series of Ce(x)-V-g-C(3)N(4) catalysts with different cerium content were synthesized by a facile co-assembly method. Compared with pure V-g-C(3)N(4) catalyst, the addition of cerium facilitated the high dispersion of vanadium species as well as the benzene adsorption ability of the corresponding catalysts. Also, the existence of cerium promoted the partial reduction of vanadium species, which improved the redox property of vanadium species as the active centres. The Ce(x)-V-g-C(3)N(4) catalysts showed considerably improved activity in the benzene hydroxylation reaction compared with V-g-C(3)N(4) catalyst. Among the catalysts studied, Ce(0.07)-0.07 V-g-C(3)N(4) exhibited the best catalytic activity with a benzene conversion of 33.7% and a phenol yield of 32.3% with good structural and catalytic stability, while only 24.7% of benzene conversion and phenol yield of 24.2% were obtained over 0.07 V-g-C(3)N(4).