类水滑石催化尿素与1,2-丙二醇合成碳酸丙烯酯

制备并表征了几种不同阳离子组合的类水滑石,研究了它们对尿素与1,2-丙二醇醇解合成碳酸丙烯酯反应的催化性能。实验结果表明,类水滑石对尿素与1,2-丙二醇的醇解反应有一定的催化活性,焙烧后类水滑石的催化活性明显提高;类水滑石中二价阳离子和三价阳离子的种类对类水滑石的催化性能具有同样重要的影响;催化剂的酸碱性可能是影响催化活性的关键因素。考察了原料配比、反应温度、反应时间和催化剂用量对反应的影响,当反应温度为170℃、1,2-丙二醇与尿素的摩尔比为4、催化剂用量为原料质量的0.25%、反应时间为5h时,Zn-A l类水滑石的焙烧产物的催化活性最高,碳酸丙烯酯的收率为98.7%。

Synthesis of Propylene Carbonate from Urea and 1,2-Propanediol Catalyzed by Hydrotalcite-Like Compounds

Several samples of hydrotalcite-like compounds(HTLcs)with different cation combinations were prepared and characterized.Their catalytic activities were studied by alcoholysis of urea and 1,2-propylene glycol to propylene carbonate(PC).The results indicated that all kinds of HTLcs possessed certain catalytic activity in alcoholysis and activities obviously increased after HTLcs was calcined at 500℃ for 6h.The species of divalent and trivalent cations on HTLcs had the same important influence on its catalytic performance.The acidity and basicity of catalyst might be the key factors that influenced the catalytic activities.The influences of mole ratio of reactant,reaction temperature,reaction time and catalyst dosage were also investigated.Under optimal reaction conditions:reaction temperature 170℃,mole ratio of 1,2-propenne glycol to urea 4,mass fraction of catalyst to total reactant 0.25% and reaction time 5h,catalytic activity of calcined Zn-Al HTLcs was the highest and yield of propylene carbonate could reach 98.7%.