A novel catalyst of copper hydroxyphosphate (Cu2(OH)PO4) with high activity in hydroxylation of phenol by hydrogen peroxide

Abstract

A novel catalyst of copper hydroxyphosphate (Cu 2 (OH)PO 4 ) that has not microporous and mesoporous pores (surface area <0.01 m 2 /g) has been successfully synthesized from hydrothermal method by using ethylenediamine, phosphoric acid, and copper acetate. Catalytic data in hydroxylation of phenol by hydrogen peroxide as a model reaction for oxidation catalysis showed that the copper hydroxyphosphate is very active catalyst, and its activity is even higher than that of microporous TS-1 catalyst that is known as one of the most effective catalysts. Furthermore, we observed that the Cu 2 (OH)PO 4 catalyst is readily regenerable to its active state by recalcining the expired form in air. Comparison of various catalysts suggests that the unusual catalytic activity on the Cu 2 (OH)PO 4 catalyst may be related to unique structure of as-synthesized Cu 2 (OH)PO 4 . Characterization of catalytic process by ESR method gives very strong signals assigned to radical OH species, showing their possible catalytic mechanism.