Au Nanoparticle Catalysts on NiO-Decorated MgO–Al2O3 Supports for Efficient Oxidative Esterification of Methylacrolein to Methyl Methacrylate

Abstract

Supported Au catalysts have been the focus of oxidation esterification of methylacrolein (MAL) to methyl methacrylate (MMA) in recent years, but most of them have difficulty in achieving both high conversion and high selectivity. Here, we report an easily prepared catalyst-loaded Au on NiO-decorated MgO–Al₂O₃, using which resulted in 97.7% MAL conversion and 91.9% MMA selectivity. XPS showed that Au existed mainly as Au⁰, while Ni existed as NiO. The addition of appropriate amounts of Ni reduced the binding energy of Au and the percentage of Au^δ+ and enhanced the interaction between Au and the support, so as to obtain high reaction activity. In situ FTIR showed that the high selectivity for MMA formation was attributed to a special η¹-(C,O) mode. Furthermore, the mechanism of the reaction was deduced from the above experimental results and different adsorption modes. We anticipate that the results provide ideas for the design of oxidation esterification catalysts.