Removal of Non-Hydrocarbon Natural Gas Impurities over Gas Hydrate Membranes

全球每年使用近100万亿标准立方英尺的天然气，使天然气加工成为最大的工业气体分离技术。天然气主要由甲烷、二氧化碳、氮气、硫化氢和其他碳氢燃料组成。从天然气中脱除非燃料杂质以提高其热含量是非常必要的。这些杂质可以用选择性膜去除，这种膜允许一个组分通过，同时保留其他组分。与需要在低温下压缩或液化气体的分离技术相比，膜可以节省能源。本工作的主要目的是合理设计用于天然气净化的新型天然气水合物膜。这项研究可能会带来一种可行的节能方法，潜在地降低与天然气净化相关的成本。这一提议的核心是合理设计一种由气体水合物组成的新型膜家族，它为天然气净化提供了展示高分离性能的可能性。这项工作的具体目标包括：(I)开发用于从甲烷中分离二氧化碳、氮气和硫醇的气体水合物膜；(Ii)了解和调节水合物形成和解离的动力学；(Iii)展示用于从甲烷中分离二氧化碳、氮气和硫醇的气体水合物膜的性能；以及(Iv)建立用于从非烃天然气杂质中分离甲烷的气体水合物膜的基本结构/分离关系。具体地说，我们提出了一种分离过程，其中将使用气体水合物膜来捕获天然气杂质，如二氧化碳、氮气和硫醇作为硫化氢的替代品。从根本上说，预计拟议的分离可能会得到动态置换的推动或支持，在动态置换中，原料气中的天然气杂质分子将与最初形成的天然气水合物中的客体分子进行交换。这种分离机制将与聚合物或无机膜材料中观察到的传统机制非常不同。最后，这项建议旨在了解与天然气水合物膜有关的基本问题、形成和解离动力学以及稳定性，这些都是开发坚固的天然气水合物膜的关键方面。制造用于工业气体分离的气体水合物膜的能力构成了膜科学的一个新的和独特的方向，最终目标是实现天然气净化的渗透性和选择性的更高组合。拟议计划的教育推广范围包括暑期研讨会和REU项目，将未被充分代表的群体纳入本科教育，以及招募少数族裔进入研究生学习。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Every year close to 100 trillion standard cubic feet of natural gas are used worldwide, making natural gas processing the largest industrial gas separation technology. Natural gas consists primarily of methane, carbon dioxide, nitrogen, hydrogen sulfide, and other hydrocarbon fuels. It is highly desirable to remove non-fuel impurities from natural gas to improve its heat content. These impurities may be removed with selective membranes, which allow one component to pass while retaining other components. Membranes can save energy relative to separation techniques that require compression or liquefaction of the gas at cryogenic temperatures. The main objective of this work is the rational design of novel gas hydrate membranes for natural gas purification. This research may result in a viable energy-saving approach to potentially reduce the costs associated with natural gas purification. The central thrust of this proposal is the rational design of a novel family of membranes, composed of gas hydrates which offer the possibility of demonstrating high separation performance for natural gas purification. The specific objectives of this work include: (i) Development of gas hydrate membranes for the separation of CO2, N2, and mercaptans from methane; (ii) Understanding and tuning the kinetics of hydrate formation and dissociation; (iii) Demonstration of gas hydrate membrane performance for the separation of CO2, N2, and mercaptans from methane, and (iv) Establish the basic structure/separation relationships of gas hydrates membranes for the separation of CH4 from non-hydrocarbon natural gas impurities. Specifically, we propose a separation process in which gas hydrate membranes will be employed to capture natural gas impurities, such as CO2, N2, and mercaptans as H2S substitutes. Fundamentally, it is expected that the proposed separation may be promoted or favored by a dynamic replacement in which there will be an exchange of natural gas impurity molecules from the feed gas with the guest molecules in the initially formed natural gas hydrate. This separation mechanism would be very distinctive from traditional mechanisms observed in polymeric or inorganic membrane materials. Finally, this proposal aims at understanding fundamental questions related to gas hydrate membrane, kinetics of formation and dissociation, and stability, which are key aspects for developing robust gas hydrate membranes. The ability to fabricate gas hydrate membranes for industrially relevant gas separations constitutes a new and distinctive direction in membrane science, with the ultimate goal of achieving higher combinations of permeability and selectivity for natural gas purification. The educational outreach of the proposed plan spans from summer workshops and REU programs, inclusion of underrepresented groups in undergraduate education, and recruitment of minorities for graduate studies.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.