An Innovative, Unorthodox, and General Strategy for the Synthesis of Zeolitic-Imidazolate Framework (ZIF) Membranes for Olefin/Paraffin Separations

用于合成用于烯烃/石蜡分离的沸石-咪唑酯框架 (ZIF) 膜的创新、非正统和通用策略

• 批准号: 1132157
• 负责人: Hae-Kwon Jeong
• 金额: $ 28.04万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1132157&HistoricalAwards=false
• 关键词: Innovative; Unorthodox; General; Strategy; Synthesis

1132157JeongThe goal of the proposed work is to develop an innovative, unorthodox, and general strategy to synthesize metal-organic framework (specifically zeolitic-imidazolate framework) membranes in a commercially viable manner for high resolution separations of olefin/paraffin mixtures such as propene/propane and ethene/ethane. Zeolitic imidazolate frameworks (ZIFs), a subclass of metal-organic frameworks (MOFs), offer unique opportunities in gas separations due to their ultra-micropores (pores smaller than 5 Å), their unique thermal/chemical stabilities, and their unparalleled framework flexibilities. For example, in ZIFs, the fundamental separation mechanism based on the differences in the solubilities and the diffusivities of gases can be controlled due to a so called gate-opening effect (more broadly known as a breathing effect) in which the adsorption and diffusion of specific molecules can be regulated by threshold pressures (i.e., flexible frameworks). Since these threshold pressures vary for different gas molecules, ZIFs possess tremendous flexibility for separation applications. However, many of the fundamental challenges hindering zeolite membranes from being more widely used in commercial applications still remain for ZIF membranes. These challenges include slow batch crystallization, grain boundary defects, and expensive porous supports. Additionally, zeolite membranes of different topology are often synthesized by trial-and-error approaches and reproducibility is still a major problem. A fundamentally different strategy needs to be developed in order to fully harvest the potential of this emerging class of nanoporous framework materials for membrane-based gas separations. Many researchers working on MOF membranes come from a zeolite membrane background and thus try to apply the same techniques and experiences that they have used in the past. In contrast, the PI proposes to take a unique perspective on the synthesis of ZIF membranes that breaks away from conventional thought. The key hypothesis is that a radically different transformative approach to synthesizing MOF membranes can be developed due to the fact that the chemistry of these materials are fundamentally different from zeolite chemistry. The proposed work will be built upon the rapid thermal deposition (RTD) technique developed in the PI's group. The proposed plan has three main objectives: 1) development of an innovative, unorthodox, and general synthesis strategy based on the RTD technique, 2) characterization and control of ZIF membrane microstructure, and 3) testing of membrane performance. The innovative strategy proposed here will be applicable for the large-scale synthesis of any MOF membrane in an unprecedented manner, thereby potentially rendering their practical applications a reality. This work will enable the PI to determine if a transformative synthesis strategy based on rapid thermal deposition can be successfully developed for ZIF membranes. The proposed fundamental research will lead to a set of design rules for the rapid synthesis of any ZIF membrane with a unique microstructure. ZIF membrane microstructures (in particular, grain boundary defects) will be characterized for the first time and then controlled to maximize separation performance. The effects of the ZIFs' framework flexibility on the pore and grain boundary structures will be determined which will in turn determine the performance of the ZIF membranes. The development of membranes capable of performing olefin/paraffin separations will lead to a technology that consumes less energy than the current practice of distillation, thereby leaving a much smaller carbon footprint. While the focus of this work is olefin/paraffin separations, the materials and their membranes investigated here will be relevant to other difficult separations facing the chemical and petrochemical industries. The interdisciplinary nature of the work, spanning material design and synthesis, characterization, and membrane fabrication and testing, will lead to a truly multidisciplinary research experience for the students (one graduate and one REU undergraduate) involved. The educational outreach activity development of science videos based on the proposed research will positively impact K-12 education by increasing public interest in science and engineering.

1132157 Jeong所提出的工作的目标是开发一种创新的、非正统的和通用的策略，以商业上可行的方式合成金属-有机骨架（特别是沸石-咪唑酯骨架）膜，用于烯烃/链烷烃混合物如丙烯/丙烷和乙烯/乙烷的高分辨率分离。沸石咪唑骨架（ZIF）是金属有机骨架（MOF）的一个子类，由于其超微孔（小于5 μ m的孔）、其独特的热/化学稳定性以及其无与伦比的骨架柔性，其在气体分离中提供了独特的机会。例如，在ZIF中，基于气体的溶解度和扩散率的差异的基本分离机制可以由于所谓的开门效应（更广泛地称为呼吸效应）而被控制，其中特定分子的吸附和扩散可以通过阈值压力（即，灵活的框架）。由于这些阈值压力对于不同的气体分子而变化，ZIF对于分离应用具有巨大的灵活性。然而，阻碍沸石膜在商业应用中更广泛使用的许多基本挑战仍然存在于ZIF膜中。这些挑战包括缓慢批量结晶、晶界缺陷和昂贵的多孔载体。此外，不同拓扑结构的沸石膜通常通过试错法合成，并且再现性仍然是一个主要问题。需要开发一种根本不同的策略，以充分挖掘这类新兴的纳米多孔框架材料用于膜基气体分离的潜力。许多从事MOF膜研究的研究人员来自沸石膜背景，因此试图应用他们过去使用的相同技术和经验。相比之下，PI建议对ZIF膜的合成采取独特的观点，打破传统思想。关键的假设是，由于这些材料的化学性质与沸石化学性质根本不同，因此可以开发出一种完全不同的合成MOF膜的变革方法。拟议的工作将建立在快速热沉积（RTD）技术开发的PI的小组。提出的计划有三个主要目标：1）基于RTD技术开发创新的、非正统的和通用的合成策略，2）ZIF膜微观结构的表征和控制，以及3）膜性能的测试。本文提出的创新策略将以前所未有的方式适用于任何MOF膜的大规模合成，从而可能使其实际应用成为现实。这项工作将使PI能够确定是否可以成功开发基于快速热沉积的ZIF膜的变革性合成策略。拟议的基础研究将导致一套设计规则，用于快速合成具有独特微结构的任何ZIF膜。 ZIF膜微结构（特别是晶界缺陷）将首次得到表征，然后进行控制以最大限度地提高分离性能。将确定ZIF的骨架柔性对孔和晶界结构的影响，这反过来将决定ZIF膜的性能。开发能够进行烯烃/烷烃分离的膜将导致一种比目前的蒸馏实践消耗更少能量的技术，从而留下更小的碳足迹。虽然这项工作的重点是烯烃/石蜡分离，但这里研究的材料及其膜将与化学和石化工业面临的其他困难分离相关。工作的跨学科性质，跨越材料设计和合成，表征，膜制造和测试，将导致一个真正的多学科研究经验的学生（一个研究生和一个REU本科生）参与。基于拟议研究的科学视频的教育推广活动开发将通过增加公众对科学和工程的兴趣对K-12教育产生积极影响。