Preparation Of Dimethyl Oxalate Hydrogenation Catalyst And Study On Its Catalytic Performance

Ethylene glycol（EG）is a very important chemical raw material.It is not only the main monomer used to prepare polyester fiber,polyester resin and alkyd resin,but also the raw material of many chemical products such as antifreeze,adhesive,plasticizer and surfactant.At present,China’s demand for ethylene glycol is relatively large.However,due to the fact that the production capacity of ethylene glycol in China has not yet reached its demand,it is necessary to import a large amount of ethylene glycol to ease the current situation in which it is in short supply.Therefore,ethylene glycol has a very wide range of application prospects,and the realization of industrial production of ethylene glycol has strategic significance for China.The petroleum-based production process is currently the most commonly used ethylene glycol production method.Its production technology is relatively mature,but the process has high energy consumption,harsh reaction conditions,and the raw material is oil,which does not meet China’s“poor oil and rich coal”.The current state of energy,and thus the synthetic route does not apply to large-scale production.Therefore,the carbon-based route using synthetic gas as a raw material has attracted extensive attention from experts.The advantages of this process are abundant raw materials,simple processes,and relatively mild conditions,which provide favorable conditions for the industrial production of ethylene glycol.Among them,the key to the process is the preparation of dimethyl oxalate（DMO）hydrogenation to ethylene glycol catalysts,but the synthesis of the catalyst has many problems such as more by-products and poor stability.Therefore,the development of a novel and efficient dimethyl oxalate hydrogenation catalyst is critical to this process route.First,this article focuses on the relatively mature Cu-based catalyst technology,using HMS,ZSM-5,HAP,MCM-41 as a carrier to prepare a series of different carrier Cu-based catalysts,and evaluate the catalytic performance of the series of catalysts.At the same time,XRD,N₂ adsorption and desorption at low temperature and FT-IR were used to characterize the analysis.The results show that the specific surface area of the Cu-HMS catalyst reaches a maximum of 764.8 m²·g^-1.The synthesized catalyst was used in the catalytic hydrogenation of DMO.Among them,the catalytic performance of Cu-HMS catalyst has obvious advantages.Under the reaction conditions of 2.0 MPa,205°C,hydrogen ester ratio of 80mol·mol^-1 and DMO liquid hourly space velocity of 0.4 h^-1,the conversion rate of DMO was99.45%,while the selectivity of EG was 93.63%.And we also studied the reaction mechanism of the catalytic hydrogenation reaction of DMO.Secondly,based on the above experimental research,a series of Cu-HMS catalysts with different copper loadings were prepared by hydrothermal synthesis using hexadecylamine as a template agent,and its catalytic performance for the reaction of hydrogenation of dimethyl oxalate to ethylene glycol was investigated.At the same time,the catalysts were systematically characterized by XRD,N₂ adsorption and desorption at low temperature,FI-IR,H₂-TPR and TEM,and other means.The results show that the copper loading has a great influence on the dispersibility of the active components of the catalyst and the interaction forces between the carriers.The experimental results show that the Cu-HMS catalyst prepared with 20%copper loading has obvious advantages in catalytic performance.The influence of reaction conditions（catalyst amount,temperature,pressure and the ratio of hydrogen to ester,etc.）on the catalytic DMO hydrogenation reaction of the catalyst was investigated to select the best process conditions:1.2 g catalyst,the reaction temperature of 205°C,the pressure of2.0 MPa,the molar ratio of hydrogen to ester of 80 mol·mol^-1 and the liquid hourly space velocity of 0.4 h^-1.The reaction is carried out under this condition:the conversion rate of dimethyl oxalate was close to 100%,and the selectivity of ethylene glycol was as high as98.11%.