锌基催化剂制备及其催化合成碳酸丙烯酯

The synthesis of propylene carbonate over zinc base catalysts

摘要:

通过尿素沉淀法制备了以锌基为主要活性组分的不同的复合型氧化物催化剂，考察了尿素与1,2-丙二醇（PG）合成碳酸丙烯酯（PC）反应的催化性能。用XRD,SEM,BET,CO2-TPD等技术对催化剂进行了表征。结果表明，催化剂的强碱性位数量可能是影响催化活性的关键因素, 在此基础上推出碱催化机理：较强的碱强度有利于降低中间产物羟丙基氨基甲酸酯（HPC）转化为PC的活化能。在反应温度170℃，反应时间1h, PG/尿素摩尔比1.5, 0.6g催化剂(尿素质量的2%)，反应压力300mmHg的条件下, PC收率高达99.8%.锌/镁1:4催化剂经过五次再生，PC收率降低了2.2%。

Abstract:

A series of zinc-based mixed oxides catalysts were prepared by urea precipitation. The catalysts were characterized by XRD, SEM, BET and CO2 -TPD and then studied for the synthesis of propylene carbonate(PC) from urea and 1, 2 - propylene glycol. The results showed the amount of alkali may be the main factors that affect the catalytic activity e.g. the strong basic sites may promote to reduce the activation energy of the reaction between PC and HPC. The yield of propylene carbonate could reach as high as 99.8% under the optimum reaction conditions:170℃，1h, PG: Urea=1.5, 300mmHg, 0.6g catalyst (quality of urea).Zn/Mg 1:4 catalyst after five times regeneration, PC yield was reduced by 2.2%.