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为了探讨α-羟基酸酯化反应机理,制备了一种稀土固体超强酸催化剂SO42-/TiO2-CeO2,并对其催化合成乳酸丙酯的最适宜反应条件和催化反应动力学进行了研究.实验表明:Ce4+改性的钛系固体超强酸催化剂与单纯使用稀土硫酸盐或钛系固体超强酸相比,具有更高的催化活性;以苯为带水剂,在酸醇摩尔比为n(乳酸)∶n(正丙醇)=1∶2.0的条件下,催化剂用量为1.0 g.0.1 mol-1(乳酸),反应温度为120℃,反应时间120 min,酯化率达到了96.5%.
In order to investigate the mechanism of α-hydroxy acid esterification reaction, a rare earth solid superacid catalyst SO42- / TiO2-CeO2 was prepared and the optimum reaction conditions and catalytic kinetics for the synthesis of propyl lactate were studied. The results show that Ce4 + modified titanium solid superacid catalyst has higher catalytic activity than the pure superacid or titanium solid superacid. When benzene is used as a water-carrying agent and the mole ratio of acid to alcohol is n ): N (n-propanol) = 1: 2.0, the amount of catalyst was 1.0 g mol·L -1 (lactic acid), the reaction temperature was 120 ℃, the reaction time was 120 min, and the esterification rate reached 96.5%.