Study Of Catalysts Preparation And Performance Of CO Coupling Catalytic To Dimethyl Oxalate

CO coupling reaction is the key step of preparing ethylene glycol with syngas.The coupling catalyst plays the key role on efficiency and selectivity.In this study,the support property,maceration liquid and process condition were investigated to measure the influence of loaded Pd/a-Al2O3 coupling catalyst,which is expected as reference of developing coupling catalyst with higher performance.In this research,the loading capacity of palladium,reaction temperature,reactant ratio and space velocity were investigated to determine the catalyst performance and product distribution.The optimal loading capacity of palladium is 1%,the optimal process condition follows:the reaction temperature is 140?,reactant ratio(CO to methyl nitrite(MN))is 1.7 to 1,the space velocity is 4000 ml·g-'·h-1,under which the conversion of MN is 81%,selectivity of DMO is 91%.The results show:(1)For the coupling catalyst with bimodal micro-pore structure,the increase of the micro-pores number on support?-Al2O3 in range of 1 to 5 nm contributes to the increase of specific surface area and conversion rate of MN.The selectivity of product DMO has positive relation with the macro-pore number in the range of 50 to 100 nm.Thus the proper pore structure contributes to the increase of conversion rate of MN and selectivity of DMO.(2)The increase of interaction between Pd2+ and ?-Al2O3 accelerate the selectivity of DMO.(3)Absolute ethyl alcohol as maceration liquid enhances this interaction,so the prepared catalyst in this liquid has a higher selectivity of DMO.