High-Performance Ni₃P/meso-SiO₂for Gas-Phase Hydrogenation of Dimethyl Oxalate to Methyl Glycolate

Three meso-SiO2 (RB-MSN, HMS, and MCM-41) supported Ni3P catalysts to be used in gas-phase hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) are prepared via the impregnation method and subsequent H2-reduction treatment. The as-obtained catalysts show interesting meso-SiO2-type-dependent reactivity for this reaction, which is tightly linked with the support Si-OH amount rather than the support textural/structural properties and Ni3P grain size. The Ni3P/RB-MSN outperforms the two others, being capable of fully converting DMO with 85.0% MG selectivity and being stable for at least 500 h under mild conditions. The turnover frequency and Ea of such a catalyst for this reaction are calculated to be 204.2 h-1 and 84.0 kJ mol-1. Lack of Si-OH in RB-MSN diminishes the interaction of NiO and POx with Si-OH groups, thereby not only enabling NiO and POx to be easily and fully reduced to form Ni3P but also suppressing the formation of harmful irreducible POx species.