Carbon Dioxide-Selective Membranes

摘要：从气体中去除二氧化碳的最先进的工艺，包括用于氢气和氨生产的合成气以及用于其净化的天然气，使用的是水胺溶液。最先进的工艺有一定的缺点，因此开发一种既节约资金又节约能源的有效工艺是很重要的。提出的研究旨在使用二氧化碳选择性膜的新方法。这种新颖的方法结合了二氧化碳的吸收和剥离，在商业技术中分两个单独的步骤进行，成为一步膜工艺。这一步分离过程不仅简化了分离过程，而且消除了商业技术的资本密集型设备。这一步法也克服了水胺溶液的热力学溶解度限制。本提案的具体目的是研究空间位阻的影响，通过在聚合物膜中加入空间位阻胺，对二氧化碳的去除。这个PI和他的同事已经证明，立体阻碍胺比无阻碍胺具有更高的CO2和H2S吸收能力（约高60%）。重要的是要看看我们是否可以将这种显著的空间位阻效应从胺水溶液扩展到固体聚合物膜相。这是第一种能够在节能合成气净化所需的相对高温（100 - 180℃）下具有高CO2渗透率和CO2/H2选择性的膜。这项工作不仅具有重大的科学意义，而且可能提供具有重要技术意义的改进膜。该项目潜在的广泛影响是重大的，因为该研究旨在采用新的二氧化碳选择性膜方法来克服商业气体处理技术的许多缺陷。这种新颖的方法结合了二氧化碳的吸收和剥离，在商业技术中分两个单独的步骤进行，成为一步膜工艺。这一步工艺不仅简化了分离过程，而且消除了对吸收塔、再生器、用于负载和再生胺溶液的两个泵的需求，以及吸收塔和再生器之间的泵操作。这一步法也克服了胺水溶液的热力学溶解度限制。因此，这种膜方法将节省大量的资金和能源。该方案衍生的膜具有许多潜在的应用，包括净化合成气以生产用于燃料电池的高纯度氢气，从烟气中捕获二氧化碳并将其封存，以及从沼气、天然气、密闭空间空气和环境空气中去除二氧化碳。

Abstract Proposal Title:Carbon Dioxide-Selective Membranes, Proposal Number: CTS-0625758, Principal Investigator: Winston Ho, Institution: Ohio State UniversityAbstract:The state-of-the-art process for the removal of carbon dioxide from gases, including synthesis gas for hydrogen and ammonia production and natural gas for its purification, uses aqueous amine solutions. The state-of-the-art process has certain draw backs and it therefore is important to develop an effective process with both capital and energy savings. The proposed research is aimed at a novel approach using a CO2-selective membranes. This novel approach combines the absorption and stripping of CO2, carried out in 2 separate steps in the commercial technology, into a one-step membrane process. This one-step process not only simplifies the separation process, but also eliminates the capital-intensive equipment of the commercial technology. This one-step process also overcomes the thermodynamic solubility limit of aqueous amine solutions. The specific objective of this proposal is to study the effect of steric hindrance, via incorporating sterically hindered amines in polymer membranes, on CO2 removal. This PI and his coworkers have shown that sterically hindered amines have much higher CO2 and H2S absorption capacities (about 60% higher) than unhindered amines. It is important to see if we can extend this significant steric effect from the aqueous amine solution to the solid polymeric membrane phase. This is the first of the kind of membranes capable of possessing high CO2 permeability and CO2/H2 selectivity at relatively high temperatures (100 180oC) needed for energy-efficient syngas purification. This proposed work not only is of a great scientific interest but also may provide improved membranes of significant technological importance. Potential broader impacts of the project are significant as this research is aimed at the novel CO2-selective membrane approach to overcome many deficiencies of the commercial gas treatment technology. This novel approach combines the absorption and stripping of CO2, carried out in 2 separate steps in the commercial technology, into a one-step membrane process. This one-step process not only simplifies the separation process, but also eliminates the needs for the absorber, the regenerator, two pumps for the loaded and regenerated amine solutions, and the pumping operations between the absorber and regenerator. This one-step process also overcomes the thermodynamic solubility limit of aqueous amine solution. Thus, this membrane approach will have both significant capital and energy savings. The membranes derived from this proposal have many potential applications including the purification of synthesis gas to produce high purity hydrogen for fuel cells, CO2 capture from flue gas for its sequestration, and CO2 removal from biogas, natural gas, confined space air, and ambient air.