CAREER: A new class of modified mesoporous silica membranes with controlled pore size and surface functionalization through unique synthetic approaches

摘要：由被称为二氧化硅的砂状材料制成的人工膜可能比蒸馏（从液体到气体的相变化）等其他分离过程更节能，因为进行分离不需要相变。此外，利用膜反应器可以将反应和分离结合在一个单元内，从而提高热力学受限反应的产率。然而，由于现有合成方法的固有局限性，制备具有孔径控制和表面化学控制的高质量二氧化硅膜仍然具有挑战性。缅因大学的研究人员利用新的合成方法制造二氧化硅膜，在孔径控制和表面化学控制方面取得了有希望的初步结果。这些技术是基于高度控制的催化表面化学反应，用于修饰介孔二氧化硅膜。这些反应在表面被原子控制，以提供一个自我限制的孔径减小和介孔基质的功能化。在这个CAREER计划中，缅因大学将使用新的合成技术，即催化原子层沉积，制备孔径控制在10-20埃范围内的二氧化硅膜，并创造新的有机/无机混合膜。这将通过气相沉积和超临界流体CO2沉积技术来实现。这将提供一种新的二氧化硅材料，可以在高分子量化合物的分离中找到应用，以及一种新的用于气体/蒸汽分离的有机/无机硅基混合膜。研究将集中在了解新材料的化学、微观结构、渗透和分离特性，同时定量地将合成过程与材料性能联系起来。提出的合成技术在材料制备过程中提供了一种目前尚不知道的原子控制水平。这些膜的应用是多种多样的，包括石油加工中重馏分的分离，从较轻的气体中分离有机化合物，锂离子电池的分离器，以及生物分离。这些新的合成技术有望促进不同类别材料的应用，包括吸附剂甚至不同的无机膜。拟议的教育活动将影响缅因大学的所有化学工程本科生和相当数量的高中生，包括缅因州一些最贫穷和地理上最偏远的社区的学生。

Abstract: Artificial membranes made from sand-like materials known as silica are potentially more energy efficient than other separation processes such as distillation (change in phase from liquid to gas) because there is no phase change required to perform the separation. In addition, the opportunity exists for combining reaction and separation within a single unit using membrane reactors, thereby increasing yield on thermodynamically-limited reactions. However, the fabrication of high-quality silica membranes with pore size control and surface chemistry control remains challenging because of the inherent limits of existing synthetic approaches used to fabricate silica membranes. The researchers at the University of Maine have achieved promising preliminary results on pore size control and surface chemistry control using new synthetic approaches toward fabricating silica membranes. These techniques are based on highly controlled catalyzed surface chemistry reactions that are used to modify mesoporous silica membranes. The reactions are atomically controlled at the surface to provide a self-limited pore size reduction and the functionalization of the mesoporous matrix. In this CAREER plan, the university of Maine will use the new synthesis technique, known as catalyzed-atomic layer deposition, to prepare silica membranes with controlled pore sizes in the pore size range of 10-20 angstroms and create new hybrid organic/inorganic membranes. This will be achieved using both vapor phase deposition and supercritical fluid CO2 deposition techniques. This will provide a new class of silica materials that may find application in the separations of higher molecular weight compounds as well as a new class of hybrid organic/inorganic silica-based membranes for gas/vapor separations. The research will focus upon understanding chemical, microstructural, permeation, and separation properties of the new materials while quantitatively linking the synthesis procedure to material performance. The proposed synthesis techniques offer a level of atomic control during the materials preparation that is not known today. The applications for these membranes are diverse and include separations of heavy distillates in petroleum processing, separations of organic compounds from lighter gases, separators for lithium-ion batteries, and bio-separations. These new synthetic techniques are expected to spur application towards different classes of materials, including adsorbents or even different inorganic membranes. The proposed education activities will affect all chemical engineering undergraduates at the University of Maine and a significant number of high school students, including those in some of Maines poorest and most geographically remote communities.