Synthesis, characterization, catalytic performance of magnetically recoverable nano-Au/MCeOx (M: Fe, Co and Ni) in direct oxidative esterification of methacrolein and methanol

Abstract

Series of magnetic metal-doped cerium oxide (MCeOx, M = Fe, Co and Ni) were synthesized and applied to support nano-gold (Au) as catalyst for synthesis of methyl methacrylate (MMA) through gas-liquid-solid three-phase oxidation esterification of methacrolein (MAL) and methanol (MeOH). Hydrothermal synthesis method was applied for MCeOx preparation and deposition-precipitation method was for nano-Au supported catalyst. The catalysts were characterized through XRD, H2-TPR, NH3-TPD, FT-IR, TG, BET, TEM-EDS and VSM. Results showed that Au/FeCeOx had strong magnetic properties and could be easily separated by external magnetism. Moreover, the doping of Fe could improve the redox properties and acidic sites of the catalyst. Catalyst performances were evaluated in a micro batch reactor. 5% - Au/FeCeOx allowed the highest reaction activity to be observed with MAL conversion of 80.2% and MMA selectivity of 96.1%. Surface catalytic reaction mechanism on Au/CeO2 was established and transition states of oxidative esterification were obtained using density functional theory (DFT). Magnetically recoverable nano-Au/FeCeOx catalysts maintain stable activity after 5 cycles, which makes it a promising catalyst for industrial application.