Study On Stability Of Catalyst For Hydrogenation Of Dimethyl Oxalate To Ethylene Glycol

Ethylene glycol（EG）is an important chemical raw material and is widely used in polyester industry,medicine,perfume and other fields.In China,the storage of coal is relatively abundant than oil and natural gas.Thus,the conversion of coal to EG may be a route to relax the pressure in the near future.The synthesis of EG from coal via dimethyl oxalate（DMO）hydrogenation represents a green,environment friendly and efficient route.Considering the important role in producing EG from coal route,hydrogenation of DMO has attracted increasing attention.At present,the Cu-based catalyst exhibited relatively excellent performance in DMO hydrogenation.However,the disadvantage of poor stability of Cu based catalyst restricted its further industrial production due to the manufacturing cost.In order to solve the problem of catalyst stability,Cr-modified copper-based catalysts were first applied in industry.Nonetheless,the acute toxicity of Cr posed a greater threat to environmental protection and human health.Therefore,it is urgent to develop a new stable and efficient catalyst.In this paper,copper-based catalysts with different structures were prepared by constructing a bimetallic catalyst and a core-shell structured catalyst.The catalysts were characterized by nitrogen physical adsorption,chemical titration,in-situ XRD,TEM,HAADF-STEM,XPS,XAES,FT-IR,ICP,etc.The catalysts were studied in combination with the results of the catalytic performance and characterization results:1.A SiO₂-supported Cu-Zn bimetal catalyst with close metal contact surface was designed.The structure-performance relationship was established by combining characterization results and catalytic tests.The intrinsic relationship between the ratio of Cu⁰/Cu⁺and catalytic performance was established.Under the optimized reaction conditions,the DMO conversion was（29）99.6%,the EG selectivity was（29）96.0%and no catalyst deactivation was found after 800 h stability test.The super stability of the catalyst due to the Cu-Zn bimetal interface that formed on the surface of the Zn-Cu/Si O₂ catalyst.2.The novel core-shell structure Cu/SiO₂@COF catalyst was synthesized by combining COF with the traditional Cu/SiO₂,which effectively improved the stability of the catalyst in hydrogenation of DMO to EG.The reason for this might be that the COF material highly dispersed on the surface of the active site Cu,which effectively suppresses the sintering of the catalyst.Under the optimal reaction conditions,the conversion of DMO was（29）99.4%and the selectivity of EG was（29）95.6%.Further,the Cu/SiO₂@COF catalyst exhibited high activity even after more than 300 h test.