Tailored Macroporous Hydrogels With Catalytic Nanoparticles for Chemical Engineering Processes

过渡金属(金、银等)在过去的20年里，用于多相催化的纳米颗粒(NPs)揭示了一系列的可能性。从水处理应用(例如偶氮染料和硝基化合物的降解)，到“更绿色”的过程(例如醇类的氧化，通常涉及有毒化合物)和新的合成途径(例如制药工业的芳香胺)，NPs在温和的条件下(T和p室，水介质)提供了巨大的化学过程潜力。NPs有不同的形状、大小和组成，即可调的反应性，并且很容易合成。NPs在化工过程中的成功集成需要(1)防止它们的团聚和聚合以保持反应性，(2)设计一种允许重复使用和容易分离的高效工艺。 水凝胶可以帮助实现这些目标，因为它们可以有效地捕获和抑制纳米颗粒的团聚，同时由于其类似液体的扩散特性，允许反应物和产物扩散到纳米颗粒表面和从纳米颗粒表面扩散。然而，由于扩散受限的传质，凝胶-纳米颗粒杂化材料的反应性通常很低。显著增强传质的一种方法是使用大孔水凝胶，它包含相互连接的孔网络(DIAM)。&gt；50 nm，IUPAC)-主要挑战是实现对孔大小、分布和互连性的精确控制，并有可能扩大制造工艺。 最近，我们开发了一种可扩展的方法来从共混聚合物中合成大孔凝胶，该方法可以很好地控制孔隙率特征，并显示出增强的传质性能。该计划的总体目标是开发形态定制、机械坚固的大孔凝胶，其中含有可控负载和反应水平的催化纳米粒子，如金。提出了三个具体目标：(1)量化聚合物共混物、多孔聚合物模具和凝胶形态对NP负载的大孔凝胶的催化和力学性能的影响，并增强其力学性能；(2)控制纳米粒子在多孔凝胶中的成核和生长，将其性能与反应性和微观结构相关联，并将合成扩展到多组分/各向异性纳米粒子；(3)作为微结构的函数，量化连续流动条件下的流动性能和反应产率。为了实现这一计划，将聘请3名博士和5名本科生实习生，从事聚合物/凝胶加工、纳米材料合成和催化工艺项目的工作，这些项目涵盖了化学工程的多个方面。长期目标是将这些材料集成到连续流动和膜反应器中，以开发新的催化、高性能化学工程工艺。

Transition metal (gold, silver, etc.) nanoparticles (NPs) for heterogeneous catalysis have revealed a wide array of possibilities in the last 20 years. From water treatment applications (e.g. degradation of azo dyes and nitro compounds), to “greener” processes (e.g. the oxidation of alcohols, classically involving toxic compounds), and new synthesis pathways (e.g. aromatic amines for the pharmaceutical industry), NPs offer significant potential for chemical processes at mild conditions (room T and p, aqueous media). NPs come in various shapes, sizes, and compositions i.e. tunable reactivity , and are easy to synthesize. The successful integration of NPs in chemical engineering processes requires (1) preventing their agglomeration and coalescence to maintain reactivity, and (2) to design an efficient process allowing reuse and easy NPs separation. Hydrogels can help achieve these goals since they efficiently entrap and inhibit NPs agglomeration, while allowing reactants and products diffusion to and from NPs surface due to their liquid-like diffusivity properties. However, the reactivity of hybrid gel-NPs materials is typically low due to diffusion-limited mass transfer. One way to significantly enhance mass transfer is to use macroporous hydrogels, which contain networks of interconnected pores (diam. > 50 nm, IUPAC) - the main challenges being to achieve precise control over pore size, distribution and interconnectivity, with the possibility of scaling up the fabrication process. Recently, we have developed a scalable method to synthesize macroporous gels from cocontinuous polymer blends, with a high level of control over the porosity features, and displaying enhanced mass transfer properties. The general goal of this program is to develop morphologically tailored, mechanically robust macroporous gels containing catalytic NPs, such as gold, at controlled loading and reactivity levels. Three specific objectives are proposed : (1) To quantify the impacts of polymer blend, porous polymer mold, and gel morphologies, on the catalytic and mechanical properties of NP-loaded macroporous gels, and to strengthen their mechanical properties; (2) to control the nucleation and growth of NPs in porous gels, to correlate their properties to reactivity and microstructure, and to extend synthesis to multicomponent/anisotropic NPs; (3) To quantify the flow properties and reaction yield in continuous flow conditions, as a function of microstructure. To realize this program, 3 PhD and 5 undergraduate student interns will be hired, working at the interface of polymer/gel processing, nanomaterials synthesis, and catalytic processes projects encompassing multiple aspects of chemical engineering. The long-term objective is to integrate these materials in continuous-flow and membrane reactors for the development of new catalytic, high performance chemical engineering processes.