活化碱式碳酸锌催化尿素与1,2-丙二醇合成碳酸丙烯酯

摘要

在不同条件下对碱式碳酸锌进行焙烧活化,得到活化碱式碳酸锌(AZCH)催化剂,将其用于尿素与1,2-丙二醇(PG)合成碳酸丙烯酯(PC)的反应;考察了活化条件对催化剂活性的影响,并对合成PC的反应条件进行了优化.实验结果表明,在焙烧温度220℃、焙烧时间2h条件下活化的AZCH催化剂活性最高;优化的反应条件为:反应温度170℃、反应时间2h、n(PG)∶n(尿素)=2.50、催化剂用量为原料质量的1.00％、真空度0.04 MPa,在此条件下,PC收率达到94.5％. XRD表征结果显示,AZCH催化剂中存在ZnO和Zn4CO3(OH)6· H2O两种晶相,其中ZnO为主活性组分,两种晶相的协同作用促进了催化剂活件的提高.%The activated basic zinc carbonate catalysts(AZCH) for synthesis of propylene carbonate(PC) from urea and 1, 2-propylene glycol(PG) were prepared under different calcination conditions. The effects of the calcination conditions on AZCH catalyst activity in the synthesis were studied. The experimental results showed that the activity of AZCH catalyst calcined at 220 ℃ for 2 h was the highest. Under the optimal reaction conditions of reaction temperature 170 ℃, reaction time 2 h, n(PG) : n(urea) 2.5, the catalyst dosage 1%(based on the total mass of the reactants) and 0.04 MPa of vacuum, PC yield reached 94.5%. XRD result showed that there were two crystal phases, ZnO and Zn4CO3(OH)6 · H2O in the catalysts where ZnO acted as the main active component, and the synergistic effect of ZnO and Zn4CO3(OH)6 · H2O promoted the catalytic activity of the catalysts.