反应条件对气相催化酯交换合成碳酸甲丙酯的影响

在连续流动气固相反应条件下,对碳酸二甲酯(DMC)与正丙醇酯交换合成碳酸甲丙酯(MPC)的反应进行了研究。研究结果表明,使用负载型氧化物TiO2/Al2O3为催化剂,在反应温度130℃、反应压力1.1MPa、原料配比n(DMC)∶n(正丙醇)=0.5、气态空速360h-1的条件下,DMC的转化率为57.27%,目标产物MPC的选择性为88.07%,收率为50.43%。随着反应温度的升高,DMC的转化率增加,但同时由于甲醚、甲丙醚和丙醚等副产物的生成,使目标产物MPC的选择性降低;反应压力的改变对合成反应的影响不显著;催化剂颗粒控制在20~40目。当气态空速为360h-1时,外扩散影响已基本消除,可获得最高的MPC收率,但是随着空速的继续增加,由于接触时间缩短,DMC的转化率和MPC的收率趋于减小。

Synthesis of Methyl Propyl Carbonate via Heterogeneous Gas - Phase Transesterification

Effect of reaction conditions on synthesis of methyl propyl carbonate(MPC)via heterogeneous gas-phase transesterification of dimethyl carbonate(DMC)and propanol had been investigated,using 5%(mass fraction)TiO2/Al2O3 as catalyst.Under optimized reaction conditions:130℃,1.1MPa,n(DMC)∶n(propanol)=0.5,GHSV=360h-1,conversion of DMC,selectivity and yield of MPC were 57.27%,88.07% and 50.43% respectively.Conversion of DMC increased along with reaction temperature while selectivity of MPC decreased due to formation of undesired ether byproducts.Change of reaction pressure showed small effect on present transesterification.Higher GHSV would favor the synthesis owing to overcoming external diffusion but conversion of DMC and selectivity of MPC decreased because of shortened residence time.Appropriate mole ratio of DMC to propanol was 0.5.