【作者】 孟超；

【导师】 陈小鹏；

【作者基本信息】 广西大学 ， 化学工艺， 2004， 硕士

【摘要】 本文以镁粉作为催化剂，研究了超临界CO₂与甲醇直接合成碳酸二甲酯的反应。用正交实验设计的方法，考察了在间歇反应釜中反应温度、催化剂用量、反应时间、及搅拌转速对反应的影响，并通过对实验数据的分析，得出理论上最佳反应条件：反应温度190℃，反应时间5h，催化剂用量6％，搅拌转速800r／min。 采用气相色谱法分析反应产物中水、甲醇和碳酸二甲酯等组分的含量，确定其色谱条件为：热导池检测器；色谱柱3×2000mm不锈钢管；固定相为60～80目的402有机担体；柱温160℃；检测室温度160℃；汽化室温度180℃；载气为氢气，流量50ml／min；桥电流110mA。并用修正面积归一法求得反应产物中各组分的相对校正因子：水为1.0000，甲醇为1.5518，碳酸二甲酯为2.5927，从而得到产物中碳酸二甲酯的含量。通过定量分析，碳酸二甲酯的转化率可达10％以上，与文献相比提高了10倍。 同时，本文对反应中出现的超临界现象作出了解释，并探讨了超临界下CO₂的活化机理。对CO₂和甲醇直接合成碳酸二甲酯反应的可行性，本文采用Benson基团贡献法从热力学上对其进行了初步分析，计算了碳酸二甲酯的ΔH_f⁰、ΔG_f⁰以及反应的一些热力学数据。计算结果表明ΔG_r⁰＞0，说明此时CO₂和甲醇直接合成碳酸二甲酯从热力学上讲是不可行的，只有通过改变反应条件，降低反应体系的△G;才可能进行。更多还原

【Abstract】 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.更多还原