Preparation of a Nanorod-like Mo-VO_x Catalyst for Gas Phase Selective Oxidation of Methyl Lactate with Air

Abstract

Selective oxidation of higher alcohols to carbonyls is one of the most important chemical transformations in research and industrial chemistry. Gas phase selective oxidation of alcohols with air as oxidant is a "green chemistry" synthesis path, although it is a great challenge to maintain high conversion with high selectivity. In this work, we synthesized nanorod-like Mo-VO x catalysts through regulation of the Mo/V ratio via a solid-state reaction method, and the group of Mo promoted VO x catalysts exhibited the combination of high catalytic activity and selectivity. The methyl pyruvate (MP) selectivity over 0.17Mo-VO x catalysts reached 79.6% at a relatively lower reaction temperature of 180 °C with 90.1% methyl lactate conversion. The characterization results revealed that the 0.17Mo-VO x catalysts showed a nanorod-like morphology with larger specific surface area and smaller crystalline size, generated active MoV 2 O 8 crystalline phase, and could give rise to active V 4+ /V 5+ redox couples as well as surface oxygen species. In terms of structure−activity relationship, when Mo was initially introduced into VO x , the MoV 2 O 8 phase was gradually formed, and MP yield over yMo-VO x catalysts increased significantly together with V 4+ proportion. However, excessive Mo would not form more active MoV 2 O 8 phases, and the MP yield decreased.