Ceramic-Carbonate Dual-Phase Membranes for High Temperature Carbon Dioxide Separation

[au:]二氧化碳在许多工业过程中大量产生，例如燃煤发电。在许多情况下，在高温下从工业气体流中分离二氧化碳是非常理想的。膜法通常比其他分离法更节能，也更容易操作。大量的微孔无机膜在低温下对二氧化碳具有过选择性，但这些膜在高温下对二氧化碳的选择性不高。本项目主要研究一种新型无孔陶瓷-碳酸盐双相膜的合成和性能研究，该膜与以往用于二氧化碳分离的多孔无机膜有本质上的区别。该膜由碳酸盐离子导电熔融碳酸盐相组成，分散在氧离子导电陶瓷相中作为支撑。陶瓷相提供了氧离子传导的途径，允许二氧化碳通过双相膜渗透。陶瓷相还为熔融碳酸盐提供了物理亲和力，确保了双相膜的良好机械稳定性。该研究旨在了解和优化新型二氧化碳半透无机膜的合成和性能，以在高温下有效地从各种气流中分离二氧化碳。将进行合成和表征实验，以优化双相膜的支撑材料、合成条件和结构，以最大限度地提高膜的稳定性、二氧化碳渗透率和选择性。本文将合成四种不同晶体结构和离子转移数的氧离子导电金属氧化物的粉末和膜，并对其在熔融碳酸盐中的化学稳定性、氧渗透性、部分电导率和表面性能进行实验研究。将合成具有不同支撑的对称厚双相膜，并对其进行表征，以确定具有最佳性能的离子导电陶瓷作为双相膜的支撑。主要的实验工作将集中在合成和表征一种不对称膜载体，它由厚而大的孔底和薄而小的孔顶层组成，两者都由相同的离子导电陶瓷制成。然后用直接渗透法将熔融碳酸盐填充到顶层，得到二氧化碳渗透率约为10-6 mol/m2.s.Pa的不对称双相膜。通过实验和模型研究二氧化碳通过不对称双相膜的渗透，以了解二氧化碳通过新双相膜的传输机制。陶瓷-碳酸盐双相膜代表了无机膜的新概念，可以推广到其他材料的双相膜，在高温下对其他气体有选择性。这项工作将对二氧化碳封存和无机膜科学产生重大影响。从事这项研究的本科生和研究生将在膜科学、分离过程、纳米结构材料和环境科学方面接受广泛的教育和培训。该项目将努力吸引亚利桑那州立大学的少数族裔本科生和女性人才库作为研究学生加入该项目。本计划所取得的成果，将透过期刊出版及会议报告，向科学界传播，并将纳入课程教材及工作坊讲座，以供研究生及其他对膜科学感兴趣的科学家及工程师使用。为高中生举办的二氧化碳捕获技术研讨会将提高年轻一代对全球变暖和环境保护的认识，并激发他们将科学技术作为职业道路的兴趣。

CBET-0828146LinCarbon dioxide is produced in large quantities in many industrial processes such as generation of electricity by burning coal. In many cases, it is highly desirable to separate carbon dioxide from industrial gas streams at high temperatures. A membrane process is generally more energy efficient and easier to operate than other separation processes. A large number of microporous inorganic membranes permselective for carbon dioxide at low temperatures have been reported, but these membranes do not offer high selectivity for carbon dioxide at high temperatures. This project is focused on the synthesis and property study of a new non-porous ceramic-carbonate dual-phase membrane fundamentally different from previous porous inorganic membranes used for carbon dioxide separation. The membrane consists of a carbonate ion conducting molten carbonate phase dispersed in an oxygen ion conducting ceramic phase as the support. The ceramic phase provides a pathway for oxygen ion conduction allowing permeation of carbon dioxide through the dual-phase membrane. The ceramic phase also offers physical affinity for the molten carbonate, ensuring good mechanical stability of the dual-phase membrane. The research is aimed at understanding and optimizing the synthesis and properties of the new carbon dioxide semi-permeable inorganic membrane for effective separation of carbon dioxide from various gas streams at high temperatures. Synthesis and characterization experiments will be performed to optimize the support materials, synthesis conditions, and structure of the dual-phase membranes in order to maximize membrane stability, carbon dioxide permeance, and selectivity. Powders and membranes of four oxygen ionic conducting metal oxides with different crystal structure and ionic transference number will be synthesized, and their chemical stability, oxygen permeability, partial electrical conductivity and surface properties with respect to molten carbonate will be studied experimentally. Symmetrical, thick dual-phase membranes with different supports will be synthesized and characterized to identify the ionic conducting ceramic with the best properties as the support for the dual-phase membranes. The main experimental efforts will be focused on synthesis and characterization of an asymmetric membrane support consisting of a thick, large pore base and a thin, small pore top-layer, both being made of the same ionic conducting ceramic. The top-layer will be subsequently filled with the molten carbonate by a direct infiltration method to give an asymmetric dual-phase membrane with carbon dioxide permeance of about 10-6 mol/m2.s.Pa. Carbon dioxide permeation through the asymmetric dual phase membranes will be studied both experimentally and by modeling to understand the carbon dioxide transport mechanism through the new dual-phase membranes. The ceramic-carbonate dual phase membrane represents a new concept of inorganic membranes which can be extended to other materials for dual-phase membranes perm-selective for other gases at high temperatures. The work will have a significant impact on carbon dioxide sequestration and inorganic membrane science. Undergraduate and graduate students working on the research will receive broad education and training in membrane science, separation processes, nanostructured materials, and environmental science. The PI will strive to target the large ASU undergraduate minority and women talent pool to join the project as research students. The results obtained in this project will be disseminated to the scientific community through journal publication and conference presentations and will be included in course materials and workshop lectures to benefit graduates students and other scientists and engineers with interest in membrane science. A workshop on carbon dioxide capture technology for high school students will improve the awareness of the young generation on global warming and environmental protection, and motivate their interest in pursuing science and technology as a career path.