Tuning the product selectivity of dimethyl oxalate hydrogenation over WO modified Cu/SiO2 catalysts

Product selectivity and reaction pathway are highly dependent on surface structure of heterogeneous catalysts. For vapor-phase hydrogenation of dimethyl oxalate (DMO), "EG route" (DMO → methyl glycolate (MG) → ethylene glycol (EG) → ethanol (ET)) and "MA route" (DMO → MG → methyl acetate (MA)) were proposed over traditional Cu based catalysts and Mo-based or Fe-based catalysts, respectively. Herein, tunable yield of ET (93.7%) and MA (72.1%) were obtained through different reaction routes over WOx modified Cu/SiO2 catalysts, and the corresponding reaction route was further proved by kinetic study and in-situ DRIFTS technology. Mechanistic studies demonstrated that H2 activation ability, acid density and Cu-WOx interaction on the catalysts were tuned by regulating the surface W density, which resulted in the different reaction pathway and product selectivity. What's more, high yield of MA produced from DMO hydrogenation was firstly reported with the H2 pressure as low as 0.5 MPa.