固定化全细胞催化可再生油脂合成生物柴油的稳定性

Stability of whole cell biocatalyst for biodiesel production from renewable oils

摘要:

酶法合成生物柴油具有反应条件温和、醇用量小、无污染物排放、产物易分离回收等优点, 越来越得到关注。全细胞催化剂, 无需酶的提取和纯化, 减少了酶活损失, 有望大幅降低生产成本; Rhizopus oryzae IFO4697全细胞可以有效催化植物油脂合成生物柴油, 进一步提高全细胞在催化植物油脂甲醇解制备生物柴油过程中的稳定性, 对于工业放大具有重要意义。本实验对固定化全细胞Rhizopus oryzae IFO4697催化植物油脂合成生物柴油的稳定性进行了系统地研究, 结果表明: 反应体系水含量对于全细胞催化剂的反应活性和催化稳定性有重要影响, 5%~15%含水量适宜; 研究范围内, 载体粒度及干燥方式对稳定性影响不显著; 经过戊二醛交联后, 全细胞催化油脂甲醇解反应的稳定性显著提高, 1200 h反应后, 仍然可以保持75%的生物柴油得率; 真空抽滤直接回用的方式有利于稳定性的保持。在优化条件下, 回用20个批次, 生物柴油得率可维持在80%。

Abstract:

Lipase-mediated biodiesel production becomes increasingly important because of mild reaction conditions, pollution free during the process and easy product separation. Compared with traditional immobilized lipase, whole cell biocatalyst is promising for biodiesel production because it is easy to prepare and has higher enzyme activity recovery. Rhizopus oryzae IFO4697 can be used as the catalyst for biodiesel production. To further study the stability of the whole cell biocatalyst is extremely important for its further application on large scale. This paper focuses on the stability study of Rhizopus oryzae IFO4697 when used for the methanolysis of renewable oils for biodiesel production. The results showed that water content was important for achieving high catalytic activity and good stability of the biocatalyst. The optimum water content was found to be 5%-15%. Both particle size and desiccation methods showed no obvious effect on the stability of the biocatalyst. With GA cross-linking pretreatment, the stability of the biocatalyst could be improved significantly. When Rhizopus oryzae IFO4697 repeatedly used for next batch reaction, direct vacuum filtration was found to be a good way for the maintenance of good stability of the biocatalyst. Under the optimum reaction conditions, the methyl ester yield could keep over 80% during 20 repeated reaction batches.