碳酸丙烯酯的CaMnO3催化尿素醇解合成

Synthesis of Propylene Carbonate from Alcoholysis of Urea Catalyzed by CaMnO3

为研究钙钛矿型催化剂对尿素醇解合成碳酸丙烯酯反应的影响,采用溶胶凝胶法制备了一系列锰基钙钛矿型催化剂,利用X射线衍射和二氧化碳程序升温脱附对催化剂进行表征分析,并考察了其在尿素醇解合成碳酸丙烯酯反应中的活性。结果表明,CaMnO3表面大量的强碱性活性位点使其具有较高的催化活性。以柠檬酸为络合剂,n(柠檬酸)∶n(总金属离子)=1∶1,1100℃焙烧5 h的条件下制备了表面碱中心数最多且结晶度最好的CaMnO3;并以CaMnO3为催化剂,在n(PG)∶n(Urea)=4∶1,催化剂用量质量分数为0.42%,170℃下反应2 h的条件下,碳酸丙烯酯收率达91.1%。

To investigate the effects of perovsikite catalysts on synthesis of propylene carbonate(PC)by urea hydrolysis,a series of Mn-based perovskite catalysts were prepared by sol-gel route and characterized by X-ray diffraction and temperature programmed desorption of CO2.Their activity in synthesis of propylene carbonate from urea and 1,2-propylene glycol were also studied.It was found that CaMnO3 had the highest activity due to the formation of strong basic sites on its surface.CaMnO3 shows the highest basicity and the best crystallinity under the preparation conditions of the molar ratio of citric acid to total metal ion of 1∶1,calcination time of 5 h and calcination temperature of 1100℃.When CaMnO3 is used as the catalyst at molar ratio of urea to 1,2-propylene of 1∶4,the reaction temperature of 170℃,reaction time of 2 h and catalyst amount of 0.42%(based on the mass of urea),the yield rate of PC is 91.1%.