Process Intensification via Bijels for Simultaneous and Continuous Catalytic Reaction and Separation

在社会对可持续制造的需求的推动下，化学工艺强化利用旨在减少能源需求和最大限度地减少环境影响的工艺。连续地同时进行催化反应和分离的膜反应器是该技术的重要示例。当被膜分离的流体相具有不同的极性（例如，油和水），油溶性试剂可以与水溶性产物反应并分离（反之亦然），进一步增加了这些系统的灵活性。膜反应器在制药工业中具有显著的影响，因为其能够将酶作为催化剂在膜内的油/水界面处驱动生物化学反应。由于酶催化反应在温和的条件和pH下进行，它们被认为是药物连续反应分离的绿色加工方法。膜反应器还可以通过去除非活性或有害的化学物质来减少农业肥料和除草剂对环境的影响。这些过程还可能影响植物油的加工，以形成用于消费品的特殊产品，所述消费品包括膳食补充剂、婴儿配方食品、药品、化妆品、食品和饮料。然而，在这些系统中，决定反应速率的界面面积限于膜反应器孔中的油-水界面。该研究计划的目标是通过引入新型高界面面积结构（称为Bijels）作为膜元件来改变基于膜的反应分离领域。这种材料允许在薄层中发生多个关键功能，具有非常高的油-水界面面积，估计比传统膜大100倍。在该项目中，甘油三酯的水解反应将在Bijel膜反应器中进行，以生产脂肪酸和甘油等原材料;这是一种工业上重要的工艺，在美国每年的市场超过250亿美元。Bijels（双连续界面堵塞的乳液凝胶）是通过使可混溶体系通过临界点淬灭以诱导相分离而形成的。这种淬灭发生在纳米颗粒存在的情况下，纳米颗粒在界面处形成堵塞层。由于油和水在Bijel膜中的特殊的双连续排列，使得界面面积随着Bijel膜厚度而增加，因此实现了高界面面积。此外，Bijels具有与蜿蜒的连续水域相邻并交织的蜿蜒的连续油域。该界面是稳定的，并装饰有纳米颗粒，也可以支持固定化酶。该研究小组将建立在他们之前成功制造bijels并通过一种称为溶剂转移诱导相分离（solvent transfer-induced phase separation，CITEPS）的可扩展方法控制其内部微观结构的基础上。研究人员还将建立在与韩国浦项科技大学的合作基础上，在该合作中，使用酶催化的批处理模式反应分离得到了证明。基于这些进展，该项目的目标是开发基于Bijel的膜反应器，以促进不同极性的试剂和产物的非均相酶催化反应，用于连续反应和分离。将使用甘油三酯与水形成甘油和脂肪酸的脂肪酶催化反应评估膜反应器性能。该研究计划的具体目标包括：（1）研究BIPPS加工条件对Bijels的影响;（2）通过数学建模和实验证明酯的连续水解;以及（3）减少膜传输限制，以创造反应速率限制性能。该项目的成功完成将通过使用新型纳米结构液膜实现工艺强化。研究团队将学习如何在具有社会重要性的过程中最佳地使用bijel技术，包括选择性对映体生产，特种化学品生产，药品和脂肪分解。在纳米结构bijels连续酶反应分离可能对对映体药物生产产生变革性影响，这类反应具有显著的经济潜力。该奖项反映了NSF的法定使命，并已被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Chemical process intensification, driven by societal needs for sustainable manufacturing, exploits processes designed to reduce energy demand and minimize environmental impact. Membrane reactors that continuously perform simultaneous catalytic reaction and separation are an important example of this technology. When fluid phases separated by the membrane are of differing polarity (e.g., oil and water), oil-soluble reagents can be reacted and separated from aqueous-soluble products (and vice versa), further adding to the flexibility of these systems. Membrane reactors have had significant impact in the pharmaceutical industry because of the ability to immobilize enzymes as catalysts to drive biochemical reactions at oil/water interfaces within the membrane. Because enzyme-catalyzed reactions operate under mild conditions and pH, they are considered a green processing approach to the continuous reactive separation of pharmaceuticals. Membrane reactors could also reduce the environmental impact of agricultural fertilizers and herbicides by removing inactive or detrimental chemical species. Such processes could also impact the processing of vegetable oils to form specialty products for consumer products ranging from dietary supplements, infant formulas, pharmaceuticals, cosmetics, food, and beverages. In these systems, however, interfacial area, which determines the rate of reaction, is limited to the oil-water interfaces in the membrane reactor pores. The objective of this research program is to transform the field of membrane-based reactive separations by introducing novel high-interfacial area structures with catalyst-laden interface areas (called bijels) as membrane elements. This material allows multiple key functionalities to occur in a thin layer, with remarkably high oil-water interfacial area estimated to be 100 times larger than conventional membranes. In this project, hydrolysis reactions of triglycerides to produce raw materials such as fatty acids and glycerol will be carried out in a bijel membrane reactor; this is an industrially significant process with an annual U.S. market in excess of $25B.Bijels (bicontinuous interfacially jammed emulsion gels) are formed by quenching a miscible system through a critical point to induce phase separation. This quench occurs in the presence of nanoparticles, which form jammed layers trapped at the interface. High interfacial area is achieved because of the special, bicontinuous arrangement of oil and water in bijel membranes that allows interfacial area to increase with bijel membrane thickness. Furthermore, bijels have a sinuous continuous oil domain adjacent and intertwined with a sinuous, continuous water domain. The interface is stabilized and decorated with nanoparticles that can also support immobilized enzymes. The research team will build on their prior success in fabricating bijels and controlling their internal microstructure via a scalable method termed solvent transfer-induced phase separation (STRIPS). The researchers also will build on their collaboration with Pohang University of Science and Technology in South Korea in which batch mode reactive separation using an enzymatic catalysis was demonstrated. Based on these advances, the project objective is to develop bijel-based membrane reactors to facilitate heterogeneous enzyme-catalyzed reactions of reagents and products of differing polarity for continuous reaction and separation. Membrane reactor performance will be assessed using the lipase-catalyzed reaction of triglycerides with water to form glycerol and fatty acids. Specific aims of the research program include (1) studying the effects of STRIPS processing conditions on bijels; (2) demonstrating the continuous hydrolysis of esters through mathematical modeling and experiments; and (3) reduction of membrane transport limitations to create reaction-rate limited performance. The successful completion of this project will enable process intensification through the use of the novel nanostructured liquid films. The research team will learn how to optimally employ the bijel technology in processes of societal importance, including selective enantiomer production, production of specialty chemicals, pharmaceuticals, and fat splitting. Continuous enzymatic reactive separation in nanostructured bijels could have transformative impact on enantiomeric pharmaceutical production, a class of reactions with significant economic potential.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.