复合催化剂催化D,L-丙交酯的合成实验研究

Study on the Catalytic Synthesis of D,L-lactide with Composite Catalyst

D，L-丙交酯（DLLA）是合成聚乳酸的关键中间体，其收率直接影响到聚乳酸的收率。采用氯化亚锡／氧化锌做为复合催化剂，研究合成丙交酯的反应条件，提高了丙交酯的收率。实验结果表明：当采用复合催化剂，氯化亚锡：氧化锌的质量比=4：1，其用量为乳酸质量的1％，在减压条件下（20kPa），130—140℃脱水3．5h，馏出温度为220℃时，可使DLLA收率最大为36．0％。

The key intermediate for synthesizing poly - lactic acid （PLA） is D, L - lactide （ DLLA ）. The yield of D, L - lactide influences that of PLA directly. The reaction conditions for synthesizing DLLA were studied with using SnCl2/ZnO as composite catalyst, and the yield of DLLA was improved. The results show that the yield of D, L - lactide reaches 36% when using SnCl2/ZnO =4：1 as catalyst, and its amount content is 1% （ based on total mass of reactants）, at low pressure （20kPa）, the dehydration time is 3.5h at 130 - 140℃ and the distillation temperature is 220℃.