Research On Catalysts For Gaseous Diethyl Oxalate Hydrogenation To Ethylene Glycol

Synthesis of diethyl oxalate (DEO) via catalytic coupling reaction from CO, then catalytic hydrogenation of DEO to ethylene glycol (EG) is a green chemical process. It is a good process in technology and economic for avoiding environment pollution and making best of CO. The catalysis used in the hydrogenation of DEO to EG has been studied in this paper.Catalytic hydrogenation of DEO to EG is a two-step process. The first step is hydrogenation of diethyl oxalate to ethyl hydroxyacetate. And the second step is hydrogenation of ethyl hydroxyacetate to ethylene glycol. Thermodynamic analysis of the reaction system indicates that the reactions of the two are reversible exothermic reactions. Lower temperature is good for the first reaction and higher temperature is good for the second one. At the same time, high temperature can produce more side products. So, appropriate temperature is needed to get high yield of target products EG. The result of analysis also indicates that experiments prove the results of thermodynamic analysis.Through the investigation of catalyst preparation methods, reagent adding methods, carriers and content of active component, it was found that the catalyst prepared by cupric nitrate and acidic silica sol and prepared by homogeneous precipitation and co-current adding methods can get high conversion and DEO yield when content of Cu is 25% in this catalyst and the reduction temperatures is 350℃. Additionally, based on this catalyst the optimal reaction conditions were studied. The optimal reaction temperature is 240℃, press is 1MPa and the optimal ratio of H2 and DEO is 200.Characteristics and active substance of the prepared catalyst have been explained by using XRD, ESEM, TPR, HRTEM and physical adsorption. The results showed that both Cu₂O and Cu0 are active to DEO catalytic hydrogenation reaction. So it is concluded that Cu₂O and Cu0 have the synergistic effect on DEO catalytic hydrogenation, and high conversion and EG yield can be expected under the proper ratio of Cu2O/Cu0.