(NH4)Cu0.2H2.8PMo11VO40 via a hydrothermal homogeneous precipitation method for selective oxidation of methacrolein to methacrylic acid

Abstract

A strategy combing homogeneous precipitation and hydrothermal treatment was proposed to prepare Keggin-type (NH4)Cu0.2H2.8PMo11VO40 for selective oxidation of methacrolein (MAL) to methacrylic acid (MAA). The effects of the preparation conditions on the catalyst properties and catalytic performance were investigated. Compared with traditional precipitation, homogeneous precipitation could provide a homogenized supersaturation for crystal initial nucleation, while the subsequent hydrothermal treatment process under high pressure could promote crystal led self-assembly growth of rectangular sediments. Benefiting from the advantages of this new method, the as-prepared (NH4)Cu0.2H2.8PMo11VO40 with high surface area and regular morphology had a large number of active species (VO2+) and acidic sites, thereby enhancing the catalytic performance of the catalyst. The MAL conversion and MAA selectivity over the optimum catalysts prepared at the hydrothermal temperature of 120 ℃ and for a time of 4 h reached above 80%. It is believed that this work offers a new strategy for the preparation of an effective catalyst for the oxidation reaction.