The synthesis of highly crystalline vanadium phosphate catalysts using a diblock copolymer as a structure directing agent
Vanadium phosphate catalysts have been widely studied for the selective oxidation of alkanes to a variety of products including maleic and phthalic anhydride. The synthesis of the precursor is a crucial factor in determining the performance of the final catalyst. Changes in the preparation procedure can alter the morphology, surface area, crystallinity and crucially, the exact vanadium phosphate phases present in the final catalyst which can all affect the selectivity and/or activity of the catalyst. In this study, the use of diblock copolymers in the preparation of phosphate oxidation catalysts has been shown to influence the crystallinity and morphology of the catalyst precursor. By adding a diblock copolymer, poly(styrene-alt-maleic acid) (PSMA), into the preparation uniform, highly crystalline VOHPO4·0.5H2O precursors are obtained, leading to a faster, more efficient, activation to the active catalyst.