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    反应-脱挥耦合制备丙交酯技术及影响因素探究

    Reaction-Devolatilization Coupling for Lactide Synthesis: Process Development and Influence Factor Analysis

    • 摘要: 针对乳酸低聚物解聚制备丙交酯过程中存在的反应效率低、产品收率低、消旋化严重等问题,本文提出了一种高效传热传质的刮膜式解聚专有设备及以循环解聚工艺。该反应器可将关键控制反应与脱挥过程进行高效耦合,并通过将未反应乳酸低聚物通过循环系统继续参与反应,结果表明,该过程可在降低温度下实现快速解聚,进而达到降低消旋化程度和提高产品收率的双重目标,丙交酯收率可达85.0%及以上,消旋化丙交酯含量可控制在6.0%以内。另外,针对连续循环解聚过程,探究了反应温度、乳酸低聚物分子量、压力及催化剂含量四个关键参数对解聚过程产品收率和品质的影响,确定了最优工艺操作条件,并通过调控催化剂添加方案,有效减少催化剂循环累积速率,提高产品收率,丙交酯产品收率最高可达89.5%,且装置操作弹性相较传统釜式解聚工艺得到有效提升,这也为丙交酯制备技术的连续、稳定化生产提供了技术支撑。

       

      Abstract: To address the challenges of low reaction efficiency, poor product yield, and severe racemization during the depolymerization of lactic acid oligomers to lactide, this study proposes a proprietary wiped-film depolymerization reactor featuring enhanced heat and mass transfer, coupled with a cyclic depolymerization process. The reactor enables efficient integration of the critical control reaction with the devolatilization step. Results demonstrate that rapid depolymerization can be achieved at reduced temperatures, thereby simultaneously minimizing racemization and enhancing product yield, with lactide yields reaching 85.0% or above and meso-lactide content controlled within 6.0%. Furthermore, for the continuous cyclic depolymerization process, the effects of four key parameters—reaction temperature, molecular weight of lactic acid oligomers, vacuum degree, and catalyst concentration—on product yield and quality were systematically investigated to determine the optimal operating conditions. By modulating the catalyst addition protocol, the accumulation rate of the catalyst in the recycle loop was effectively reduced, and the maximum lactide yield reached 89.5%. The operational flexibility of the unit was significantly improved compared to conventional stirred-tank depolymerization processes, providing technical support for the continuous and stable production of lactide.

       

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