Histidine-derivate modified Cu/SiO2 catalyst for selective hydrogenation of dimethyl oxalate to methyl glycolate

Histidine-derivate doping was proved as an effective strategy for improve the selectivity of methyl glycolate (MG) in dimethyl oxalate (DMO) hydrogenation over typical Cu/SiO2 catalyst. Based on the near-total conversion of DMO, 82.9 % MG selectivity could be obtained over His7-Cu/SiO2 catalyst, which was obviously higher than that of un-modified Cu/SiO2 catalyst (15.7 %). Detailed study revealed that histidine retains its skeleton framework (imidazole) after thermal treatment, which plays a crucial role in enhancing the selectivity towards MG. [Display omitted] •Histidine derivate was proved as an effective promoter for production of MG from DMO.•The kinetic study disclosed the key step for high selectivity of MG.•The electronic property of surface Cu species was modulated by Cu–N interaction.•Reaction mechanism was in-depth investigated by in situ DRIFTS technology. Cu-based catalysts are extensively employed in dimethyl oxalate (DMO) hydrogenation, but it is rather challenging to obtain methyl glycolate (MG) over traditional Cu-based catalysts with high selectivity at high DMO conversion. Herein, the physicochemical properties of the typical Cu/SiO2 catalyst and its corresponding catalytic performance toward DMO hydrogenation were tuned by surface modification with a biological template (histidine). On the premise of near-total conversion of DMO, the MG selectivity substantially increased from 15.7 % to 82.9 % when the typical Cu/SiO2 catalyst was modified by 7 wt% histidine, which was fairly impressive among the reported results up to now. Furthermore, comprehensive characterization and kinetic study disclosed the underlying mechanism. After thermal treatment, histidine retains its skeleton framework (imidazole), the emerging Cu–N interaction weakened the Cu-silica interaction, leading to the reduction in percentage of Cu+ and increase in electron density on the Cu/SiO2 catalyst. As a result, the adsorption and activation ability toward MG were obviously suppressed, which was proved as the critical step for selective hydrogenation of DMO toward MG.