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

摘要：由砂状材料（称为二氧化硅）制成的人造膜可能比其他分离过程（如蒸馏（从液体到气体的相变））更节能，因为进行分离不需要相变。此外，存在使用膜反应器将反应和分离组合在单个单元内的机会，从而增加在化学上受限的反应的产率。然而，由于用于制造二氧化硅膜的现有合成方法的固有限制，具有孔径控制和表面化学控制的高质量二氧化硅膜的制造仍然具有挑战性。缅因州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，用于改性介孔二氧化硅膜。反应在表面原子控制，以提供自限孔径减小和介孔基质的官能化。在这个CAREER计划中，缅因州大学将使用新的合成技术，即催化原子层沉积，制备孔径在10-20埃范围内的可控孔径二氧化硅膜，并创造新的混合有机/无机膜。这将使用气相沉积和超临界流体CO2沉积技术来实现。这将提供一类新型二氧化硅材料，可用于分离较高分子量化合物，以及一类新型混合有机/无机二氧化硅基膜，用于气体/蒸气分离。该研究将侧重于了解新材料的化学，微观结构，渗透和分离性能，同时定量地将合成过程与材料性能联系起来。所提出的合成技术在材料制备过程中提供了一种目前尚不清楚的原子控制水平。这些膜的应用多种多样，包括石油加工中重馏分的分离、有机化合物与较轻气体的分离、锂离子电池的分离器和生物分离。这些新的合成技术有望刺激不同类别材料的应用，包括吸附剂甚至不同的无机膜。拟议中的教育活动将影响缅因州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位置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.