Amino functionalization of support toward enhanced selective hydrogenation of dimethyl oxalate to methyl glycolate on silver-silicon catalyst

Abstract

The development of highly efficient catalyst for selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) is an important step in the conversion of syngas into high-value chemicals, which is of great significance for reducing dependence on petroleum and facilitating the transformation of energy structure. Herein three Ag nanoparticles with different structures were supported by mesoporous silica microspheres (MSNS) with uniform center-radial mesopore channels (～7nm). The effects of the electronic and crystal structures of Ag nanoparticles on the adsorption and activation of DMO and H₂ were studied. The characterization results reveal that amino-functionalization of support enables the silver-silicon catalyst to possess the easily accessible highly dispersed Ag active components, the lattice defects which are conducive to the adsorption, activation and diffusion of H₂, as well as electron-rich Ag^δ- species beneficial for the adsorption and activation of DMO, thereby endowing it with high activity, selectivity, and stability. In the reaction of DMO to MG, under the conditions of P = 2.0 MPa, T = 220 °C, H₂/DMO molar ratio = 80, and LHSV = 1.0 h^-1, the best catalytic state achieved a DMO conversion of 100%, a MG selectivity of 96.6%, a TOF as high as 207, and the MG yield could still remain above 95% after a 250 h lifetime investigation. Our research points out a promising way for the development of high-performance Ag catalysts used in the synthesis gas to MG process.