Study On Direct Synthesis Of Dimethyl Carbonate From Carbon Dioxide And Methanol Under Supercritical CO₂ Condition

In this paper, the direct synthesis of dimethyl carbonate(DMC) by the reaction of methanol with carbon dioxide in the presence of Mg powder near the critical point of CO2 was studied in the autoclave. The influences of reaction temperature, amount of catalysts, reaction time and agitating velocity on the production of DMC were investigated by orthogoal experiment. It shows that the optimum reaction temperature is 190 C, amount of catalysts is 6%(based on methanol weight), reaction time is 5h and agitating velocity is 800r/min.The contents of DMC, methanol and water in the product of methanol with carbon dioxide to dimethyl carbonate was analyzed by 102G gas chromatography and the gas chromatography conditions were as follows: TCD detector; chormatographic column; stainless steal( 3 2000mm) pipe; stationary phase: 60-80 mesh organic support; column temperature was 160 C; detector temperature was 160 C; vaporizer temperature was 180 C; hydrogen was used as gas carried and flow rate of gas carried was 50ml/min; bridge current was 110mA. The products were analyzed quantitatively by corrected area normalization method. The relative response factors were considered as follows: H2O is 1.0000,CH3O is 1.5518, DMC is 2.5927, and calculated the production of DMC. Through the quantitative analysis, the contents of DMC received 10%, which was ten times as documents.At the same time, the preliminary explanation was made for the supercritical phenmena and reaction mechanism in the experiments. Hf0 , Gg0 and other thermodynamic data of DMC are calculated by the method of Benson group contribution. The results shown that when Gr0 >0, the reaction of methanol with carbon dioxide did not go on by thermodynamics. It only changes the condition of reaction and reduce Gr of the system of reaction.