School of Chemistry and Chemical Engineering, Institute of Molecular Science, Shanxi University , Taiyuan 030006, China.
Food Colloids Group, School of Food Science and Nutrition, University of Leeds , Leeds LS2 9JT, United Kingdom.
J Am Chem Soc. 2017 Dec 6;139(48):17387-17396. doi: 10.1021/jacs.7b07731. Epub 2017 Nov 17.
We develop a novel strategy to more effectively and controllably process continuous enzymatic or homogeneous catalysis reactions based on nonaqueous Pickering emulsions. A key element of this strategy is "bottom-up" construction of a macroscale continuous flow reaction system through packing catalyst-containing micron-sized ionic liquid (IL) droplet in oil in a column reactor. Due to the continuous influx of reactants into the droplet microreactors and the continuous release of products from the droplet microreactors, catalysis reactions in such a system can take place without limitations arising from establishment of the reaction equilibrium and catalyst separation, inherent in conventional batch reactions. As proof of the concept, enzymatic enantioselective trans-esterification and CuI-catalyzed cycloaddition reactions using this IL droplet-based flow system both exhibit 8 to 25-fold enhancement in catalysis efficiency compared to their batch counterparts, and a durability of at least 4000 h for the enantioselective trans-esterification of 1-phenylethyl alcohol, otherwise unattainable in their batch counterparts. We further establish a theoretical model for such a catalysis system working under nonequilibrium conditions, which not only supports the experimental results but also helps to predict reaction progress at a microscale level. Being operationally simple, efficient, and adaptive, this strategy provides an unprecedented platform for practical applications of enzymes and homogeneous catalysts even at a controllable level.
我们开发了一种新颖的策略，基于非水相 Pickering 乳液，更有效地、更可控地处理连续酶催化或均相催化反应。该策略的一个关键要素是通过在柱式反应器中用油填充载有催化剂的微米级离子液体（IL）液滴，从“底部向上”构建宏观连续流动反应系统。由于反应物不断流入液滴微反应器，产物不断从液滴微反应器中释放，因此这种系统中的催化反应可以不受传统间歇反应中建立反应平衡和催化剂分离的限制。作为概念验证，使用这种基于 IL 液滴的流动系统进行的酶促对映选择性酯交换和 CuI 催化环加成反应，与它们的间歇反应相比，催化效率分别提高了 8 到 25 倍，并且对 1-苯乙醇的对映选择性酯交换的耐久性至少为 4000 小时，这在它们的间歇反应中是无法实现的。我们进一步建立了一个适用于非平衡条件下的这种催化系统的理论模型，该模型不仅支持实验结果，还有助于在微观尺度上预测反应进展。这种策略操作简单、高效且适应性强，为酶和均相催化剂的实际应用提供了一个前所未有的平台，甚至可以实现可控水平。
