首先评价了金属氧化物催化剂对尿素与1,2-丙二醇(PG)合成碳酸丙烯酯(PC)反应的催化性能,其中MgO催化活性最高,PC收率为85.5%.通过正交实验确定最佳反应条件:反应温度为170℃,MgO催化剂与PG的摩尔比为0.032:1,PG与尿素的摩尔比为3:1,反应时间为3h.此时PC收率为91.5%.为利于催化剂与反应体系的分离,又以硝酸镁为前驱体,制备了用于该反应的SiO2负载MgO催化剂,确定了最佳负载量为15‰最佳焙烧温度为550℃,PC收率为86.3%.
The catalytic performances of a series of metal oxide catalysts in the reaction for synthesis ofpropylene carbonate (PC) from urea and 1,2-propylene glycol (PG) had been evaluated. MgO showed the highest activity and PC yield amounted to 85.5%. The optimal reaction conditions had been determined by using orthogonal test design : reaction temperature 170 ℃, molar ratio of MgO to PG 0.032 : 1, and molar ratio of PG to urea 3 : 1, reaction time 3 h. Under the condition mentioned above, PC yield reached 91.5%. Silica-supported MgO catalyst had been prepared to facilitate both recovery of the catalyst and separation of the reaction product. The suitable precursor was magnesium nitrate. The load of MgO and calcinations temperature were 15% and 550℃ respectively. PC yield was 86.3%.