Tunable Synthesis of Ethanol or Methyl Acetate via Dimethyl Oxalate Hydrogenation on Confined Iron Catalysts

Oxygenated chemicals are essential to modern industries. However, selective syntheses with controllable products are still challenging over a single heterogeneous catalyst. Herein, a confined iron catalyst is designed for balanced syntheses of ethanol and methyl acetate via dimethyl oxalate (DMO) hydrogenation. With the characteristic structure of a microsphere, the Fe@C catalyst promotes the enrichment of hydrogen to reach a tunable selectivity of ethanol (84.3%) and methyl acetate (77.9%). The highest selectivity of methyl acetate is reached at a H2/DMO molar ratio as low as 20, which is the lowest among catalysts reported for DMO hydrogenation by now. The molecule-level mechanism of DMO hydrogenation is further investigated. It proves that Fe5C2 in Fe@C is the main active center of DMO hydrogenation and Fe3O4 promotes the conversion of the intermediate especially in a low H2/DMO molar ratio. This work provides a strategy for tuning targeted oxygenated chemicals.