ZnO-PbO催化剂上酯交换法合成碳酸二甲酯

Synthesis of Dimethyl Carbonate by Transesterification over ZnO-PbO Catalyst

采用共沉淀法制备了ZnO-PbO催化剂,并对该催化剂在碳酸丙烯酯(PC)与甲醇酯交换合成碳酸二甲酯(DMC)反应中的催化性能进行了研究。探讨了催化剂制备条件对ZnO-PbO催化剂性能的影响,得出最佳制备条件为:Pb(CH3COO)2.3H2O和Zn(NO3)2.6H2O为前体、m(Zn)∶m(Pb)=3.46、以n(NaOH)∶n(Na2CO3)=3∶1的混合溶液为沉淀剂、焙烧温度500℃。优化了ZnO-PbO催化剂上PC与甲醇酯交换合成DMC反应的条件,即反应温度110℃、反应时间2h、n(CH3OH)∶n(PC)=8.4、催化剂占体系的质量分数为3.0%。在此条件下,PC转化率为63.8%,DMC选择性为97.8%,产率为62.4%。此外还考察了催化剂重复使用的效果,并对其失活原因进行了分析。

A heterogeneous catalyst, zinc -lead oxide, was prepared by coprecipitation method. Its catalytic performance in synthesis of dimethyl carbonate (DMC) by transesterification of propylene carbonate (PC) and methanol was studied. Different conditions in preparation of zinc-lead oxide, such as precursors of Zn and Pb, precipitants, mass ratio of Zn and Pb, and calcination temperature were investigated. Optimal preparation conditions were as follows: Zn(NO3)2 · 6H2O and Pb(CH3COO)2 · 3H2O as precursors, m(Zn):m(Pb) =3.46, n(NaOH):n(Na2CO3) =3:1 as precipitant ,and calcination temperature 500°C. Effects of reaction conditions on performance of ZnO-PbO catalyst were also studied. When reaction temperature 110 °C, reaction time 2 h, mole ratio of methanol to PC, 8.4 and mass fraction of catalyst, 3.0%,conversion of PC, selectivity of DMC and yield of DMC could reach 63.8%, 97.8%, and 62.4%, respectively. Reusability of catalyst was examined and cause of deactivation was analyzed.