Synthesis Of Dimethyl Carbonate By Electroreduction Of Carbon Dioxide With Cuprous Oxide

The increasing consumption of conventional fossil fuels and the steady increase of CO₂concentrations in the atmosphere have led to the worsening of environmental problems.The researchers turned their attention to the fixation and conversion of CO₂.Electroreduction of CO₂into value-added compounds has been identified as a promising route of renewable carbon cycle,which could ease concerns about global warming.Compared with the traditional C₁products,the high-value multi-carbon products obtained by the electroreduction of CO₂have significant economic benefits,which is of great interest to researchers.CO₂can be reduced to multiple C products such as ethanol,n-propanol and ethylene by electrochemical method,among which one of the better products is dimethyl carbonate（DMC）.DMC is widely used as a non-toxic substitute for dimethyl sulfate and phosgene,and is regarded as a promising green chemical product.At present,a large number of studies have been carried out on the synthesis of DMC using CO₂as raw material.However,the results are not satisfactory due to the difficulties in the activation of CO₂and the easy deactivation of catalyst.As a result,new routes to synthesizing DMC are constantly emerging.Among them,electrochemical technology provides an effective solution for the activation and conversion of CO₂.Using electrochemical technology to synthesize DMC is not only easy to operate,mild conditions,but also does not appear a new CO₂source in the experimental process.Therefore,this paper focuses on the electrocatalytic reduction of CO₂with Cuprous oxide（Cu₂O）catalyst.The main work are as follows:（1）Cu₂O thin films were prepared by one-step anodic oxidation,and the effect of different anodic oxidation time,current density and electrolyte concentration on Cu₂O thin films were investigated by SEM,XRD and XPS,etc:The length of anodic oxidation time can control both the size of Cu₂O particles and the growth thickness of Cu₂O films.The current density can cause the morphology change of Cu₂O from particle to sheet,but has little effect on the thickness of the material.The concentration of electrolyte can control the aggregation of particles,and control the growth of film thickness.（2）The electrochemical properties of Cu₂O thin films prepared under various conditions and the effect on the synthesis efficiency of DMC were investigated by using CV,LSV and Tafel electrochemical test methods.The results show that the optimal conditions for the preparation of the material are as follows:preparation time is 1500 s,current density is 3 m A cm^-2,and electrolyte concentration is 3 mol L^-1.The yield of DMC can reach 49.48%when the thin film Cu₂O-3-3-1500 electroreduced CO₂.（3）Under normal temperature and pressure,the synthesis conditions of DMC were optimized by single factor experiment and orthogonal experiment.The effects of[Bmim][BF₄]concentration,methanol concentration,solvent type and alkaline salt type on the efficiency of DMC were discussed respectively.The results show that the optimal conditions for synthesis of DMC are as follows:the concentration of ionic liquid is 4 mol L^-1,the concentration of methanol is 0.18 mol L^-1,potassium carbonate as basic salt and acetonitrile as solvent.Under these conditions,the yield of DMC can reach 52.86%.