离子液体中K_2CO_3/CH_3I直接催化合成碳酸二甲酯

利用高压间歇反应釜,考察了K2CO3/CH3I催化CO2与甲醇直接合成碳酸二甲酯(DMC)的反应规律,得到最佳的反应条件:反应温度363K、反应压力3.6M Pa、反应时间8h、m(甲醇)∶m(CH3I)∶m(K2CO3)=12∶2.3∶1。液相产物中DMC含量随K2CO3用量的增加几乎呈直线增加,因此可以在较低的反应压力下获得较高的DMC收率。另外,利用离子液体溴代1-乙基-3-甲基咪唑盐Em im]B r对CO2的溶解特性,研究了离子液体Em im]B r对K2CO3/CH3I催化CO2与甲醇直接合成DMC反应规律的影响。实验结果表明,在反应温度低于393K、反应压力高于4.0MPa的条件下,离子液体Em im]B r可以加快反应速率,对反应具有一定的促进作用,但不能改变反应的最佳条件和整体规律性。甲醇、CH3I、Em im]B r、K2CO3的最佳质量比为12∶2.3∶1.6∶1。

Synthesis of Dimethyl Carbonate Catalyzed by K2CO3/CH3I in Ionic Liquid

Direct synthesis of dimethyl carbonate(DMC)from carbon dioxide and methanol catalyzed by K_2CO_3/CH_3I in ionic liquid of 1-ethyl-3-methyl-imidazole bromine salt(Br)was studied.The optimal reaction conditions were temperature 363K,pressure 3.6MPa,time 8h and m(CH_3OH) ∶(m(CH_3I)) ∶m(K_2CO_3)=12 ∶2.3 ∶1.High yield of DMC under lower pressure could be obtained since it linearly increased with increase of K_2CO_3 dosage.Due to good dissolution of carbon dioxide in(Br,)effect of ion liquid on direct synthesis of dimethyl carbonate was investigated.Although yield of DMC did not improve much in presence of ionic liquid,and optimal reaction conditions and mechanism of reaction kept unchanged,but reaction could be accelerated by Br at lower than 393K and higher than 4.0MPa.The optimal mass ratio of CH_3OH,CH_3I,Br and K_2CO_3 was 12 ∶2.3 ∶1.6 ∶1.