Study On Promoters Of Catalysts For Gaseous Diethyl Oxalate Hydrogenation

Ethylene glycol (EG) and ethyl glycolate (MPEG) are both versatile organic synthesis intermediates. Not only the economic chemicals can be produced, but also the resources of coal and natural gas can be sufficiently utilized via the hydrogenation of diethyl oxalate (DEO) which can be made from synthesis gas. The technology is very important in both safety of energy sources and protection of environment fields. In this paper, the method of catalysts preparation and the effects of promoters are studied.The catalysts prepared through method 1 were tested as the reaction temperature, pressure, molar ratio of H2/DEO and LHSV were set to 240℃, 1MPa, 200 and 0.3h-1, respectively. The results showed that EG selectivity increased because of the addition of Zn; DEO conversion and EG selectivity increased as the introduction of Cr. 3 wt% of Mo can help DEO convert and the desired product yield reach 95.4% and 94.0%, respectively.A series of catalysts were prepared through method 2. DEO conversion of 86.9% and the desired product yield of 79.0% were obtained by using Cu25(2) catalyst when the reaction temperature, pressure, molar ratio of H2 /DEO and LHSV were 220℃, 2.5MPa, 60 and 0.6h-1. The Cr0.05 (2) catalyst which had a longer serve life can increase DEO conversion and the desired product yield to 95.8% and 74.2%, respectively.Several characterization methods, such as TPR, N2 absorption, XRD, SEM, ICP and XPS, were applied to discuss the content of active component and the effects of the promote elements. It is found that the promoters influence the performances of catalysts mainly by changing the surface configurations. It is indicated that the pore volume and pore size were enlarged by adding Zn, the size of active sites was reduced and the distribution was better due to the influence of 3wt% Mo. The surface of Cr0.05 (2) catalyst was obviously extended because of the effect of Cr. As a result, the catalytic performances were advanced by enhancing desired product yield, DEO conversion or life.