Study On New Copper Based Catalyst In The Process Of Coal To Ethylene Glycol

Coal-to-ethylene glycol（EG）is a green and atomically economical ethylene glycol production technology（2C+2H₂+H₂O+0.5O₂→（CH₂OH）₂）.Its clean,high-value conversion and utilization of coal resources are in line with the current situation of energy structure in China.Coal-to-ethylene glycol can not only reduce the dependence on petroleum,but also have far-reaching practical and strategic significance for promoting the diversified development of energy resource utilization and continuously satisfying the supply of ethylene glycol market in China.The bottleneck of industrial utilization of coal-to-ethylene glycol technology lies in the development of high-efficiency dimethyl oxalate（DMO）hydrogenation catalyst.Although coal-to-ethylene glycol technology has been initially industrialized in China,DMO hydrogenation catalyst still has some problems in industrial application,such as poor stability and easy generation of by-products 1,2-butanediol（1,2-BDO）.Therefore,it is particularly important to develop a new DMO hydrogenation catalyst with high activity,high stability and no by-product 1,2-BDO formation.First,mesoporous silica（MS）supports with different texture characteristics were prepared by adjusting the alkalinity of feedstock solution.The catalytic hydrogenation performance and system characterization of the copper catalyst supported by MS supports were evaluated.It is found that the alkalinity of feedstock solution significantly affected the pore structure of MS supports and the structure and composition of the supported copper catalyst.Cu/MS2 catalyst showed better DMO hydrogenation performance because of its high copper dispersion,suitable acid sites and high Cu⁺/（Cu⁺+Cu⁰）ratio.Its conversion of DMO is100%,selectivity of EG is 94.13%,but some 1,2-BDO is still formed（0.63%）.Second,on the basis of the above experiments,the effects of molybdenum species and boron species on the catalytic performance of Cu/MS2 catalysts were investigated.It was found that with the increase of Mo species content,the dispersion of Cu species in catalysts decreased,the reduction temperature and surface acid content increasedand the Cu⁺proportion decreased.The introduction of Mo species can inhibit the production of 1,2-BDO to a certain extent,but does not significantly improve the catalytic activity of DMO hydrogenation.At the same time,the introduction of excessive Mo species will lead to the rapid decline of catalytic activity,which is not conducive to the reaction.Compared with the Cu/MS2 catalyst,the EG selectivity of the 1Mo-Cu/MS2 catalyst is slightly increased to94.89%,while the 1,2-BDO selectivity is reduced to 0.29%.The introduction of boron species brought about a series of beneficial changes to Cu/MS2 catalysts.For example,the boron species can improve the dispersion and stability of active copper species,reduce the reducibility of Cu⁺species and maintain the suitable Cu⁺/（Cu⁺+Cu⁰）ratio through the interaction between boron species and surface copper species,so that the boron modified Cu/MS2 catalysts show excellent DMO hydrogenation performance.The results show that the DMO conversion of 3B-Cu/MS2 catalyst is 100%,the EG selectivity is 98.24%,and no1,2-BDO is generated.The stability of 3B-Cu/MS2 catalyst is over 200 h.In addition,the introduction of acidic boron species improve the weak acidity of the catalyst surface and inhibited the formation of by-product 1,2-BDO at the source.