Recent Advances in Aerobic Photo‐Oxidation of Methanol to Valuable Chemicals

Abstract

AbstractThe oxidation of photocatalytic methanol into valuable chemicals is of considerable importance to the growth of the chemical industry. TiO2 has been proven to be a catalyst for methanol photocatalytic oxidation to valued chemicals (e. g. methyl formate and dimethoxymethane) at room temperature with an inferior activity. Recently, it has become a hot research topic due to its low interaction temperature with fewer by‐products. Further, the introduction of IB metal particles (i. e. Cu, Ag, and Au) upon the surface of titania can drastically enhance the catalytic activity in the photo‐oxidation, which is mainly due to metal nanoparticles can optimally enhance the efficiency of the isolation of photo‐generated holes and electrons as well as dissociate oxygen molecules. Herein, we review recent progress of the photocatalysis of methanol toward the production of chemicals over different photocatalysts (e. g., TiO2P25, M NPs/TiO2, where M=CuO, Ag2O, Au, PtO, etc). Moreover, we also glean an understanding of the catalytic mechanism and conversion pathway at play, which is confirmed by STM, in‐situ ATR‐IR, DFT simulations, etc. The reaction pathway of photo‐oxidation is different from that in the thermal process. A pivotal intermediate is absorbed formaldehyde (HCHO*), which is formed via an oxidative dehydrogenation over the redox sites of catalysts. Then the generated HCHO* directly reacts with neighboring methanol to give methyl formate (on redox sites) and dimethoxymethane (on acidic sites through a scrambling movement).