The base-free and selective oxidative transformation of 1,3-propanediol into methyl esters by different Au/CeO₂ catalysts
2011
Wang, Xiangwei | Zhao, Guoming | Zou, Huibin | Cao, Yujin | Zhang, Yongguang | Zhang, Rubing | Zhang, Fan | Xian, Mo
Different Au/CeO₂ catalysts, prepared by depositing gold on different facets of ceria nanocubes ({100}), nanorods ({110} and {100}) and nanopolyhedra ({111} and {100}), were separately characterized by means of XRD, N₂ sorption, TPD and TPR. It was found that certain types of Au/CeO₂ could selectively catalyze the oxidative transformation of 1,3-propanediol in methanol to methyl 3-hydroxypropionate, methyl 3-methoxypropionate, methyl acrylate or dimethyl malonate by molecular oxygen in the absence of any base. The selectivities of these Au/CeO₂ catalysts depended on the shapes of the supporting CeO₂ and the reaction temperature. The Au/CeO₂ cube catalyst with less acidic and basic sites exhibited high selectivity towards methyl 3-hydroxypropionate (93.1% at 21.6% conversion). Comparatively, selectivities towards methyl acrylate (41.6% at 92.3% conversion) and methyl 3-methoxypropionate (40.2% at 92% conversion) increased using Au/CeO₂ rod and polyhedron catalysts, which contained more acidic and basic sites than the cube catalyst. Moreover, we found the Au/CeO₂ cube catalyst could be recycled without losing the gold nanoparticles.
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