DFT-based Design and Experimental Testing of Catalytic Metallic Membranes for Selective N2-

技术影响目前世界人口刚刚超过70亿，如果没有氨合成过程，其中30 - 35亿人将不复存在。然而，这一过程约占世界能源消耗的2.5%。据联合国估计，到本世纪末，世界人口预计将达到100亿，这将不可避免地导致进一步依赖世界有限的能源来生产氨肥。二氧化碳排放量也会相应增加，因为能源很可能来自碳氢化合物氧化。在最近发布的《化学工业能源和温室气体减排技术路线图》（IEA、ICCA和Dechema， 2013年）中，用改进的工艺技术替代这种工艺技术已被确定为最优先事项之一。该奖项由美国国家科学基金会催化与生物催化项目和化学与生物分离项目联合颁发给斯坦福大学的Jennifer Wilcox教授，以研究一种显著降低能量需求的氨合成替代策略。该技术涉及到催化膜反应器的设计和测试，该反应器将用于从进料流（膜的前部）中解离N2，从而导致原子N通过金属膜的整体晶体结构传输。在渗透流（膜的背面）中，H2将被用作扫气，理想情况下导致N-H偶联反应和随后的氨合成。这项技术允许地球上丰富的元素，如钒和铌（而不是贵金属）被用作氮解离和运输的主要金属。Wilcox通过早期NSF EAGER项目展示了一些分离和反应的初步数据。剩下的很大的技术风险是设计膜和反应器系统，以有效的速率进行分离和催化所有的反应。更广泛的影响拟议工作结果的更广泛影响是多方面的。这项技术为在常压下进行氨合成过程提供了一条途径，为农业化学工业节省了大量资金。化肥是确保全球粮食生产充足的最重要因素之一。需求肯定会增加，因为它与世界人口的增长成正比。与传统的高压Haber-Bosch工艺相比，采用选择性n2膜技术可以以更低的能源成本生产氨。除了基于科学和技术的更广泛的影响外，PI计划将这项研究的结果纳入她在斯坦福大学能源工程系开发的碳捕获课程中。威尔科克斯是科学领域女性的榜样，她所指导的大量女性本科生和研究生都证明了这一点。这个项目令人兴奋的潜力应该会进一步吸引更多的女性进入工程学科。工作成果的进一步传播将通过私人调查团进行。他参加了由美国能源部化石能源办公室支持、南方公司每年主办的暑期学校项目“碳封存研究经验”。暑期学校为学生提供有关二氧化碳捕获和储存的实践经验，其他主办单位包括阿拉巴马州电力公司和国家碳捕获中心，该中心支持在试点规模上测试早期捕获技术。在整个奖项期间，PI将通过每年的暑期学校项目提供的课程展示调查结果。

Technical ImpactsThe current world population is just above 7 billion, of which 3-3.5 billion would not exist without the ammonia synthesis process. However, this process constitutes approximately 2.5% of the world's energy consumption. The United Nations estimate that world population is forecasted to reach 10 billion by the end of the century, which will inevitably lead to further reliance on the world's limited energy resources to produce ammonia fertilizer. There will be a corresponding increase in CO2 emissions, since the energy will likely be sourced from hydrocarbon oxidation. Replacement of this process technology with an improved process has been identified as one of the highest priorities in the recently published Technology Roadmap for Energy and GHG Reductions in the Chemical Industry (IEA, ICCA and Dechema, 2013). This award made jointly from the National Science Foundation Catalysis & Biocatalysis Program and the Chemical & Biological Separations Program is made to Professor Jennifer Wilcox of Stanford University to investigate an alternative strategy for ammonia synthesis with significantly reduced energy requirements. The technology involves the design and testing of a catalytic membrane reactor that will be used to dissociate N2 from the feed stream (front side of the membrane), leading to atomic N transport through the bulk crystal structure of the metallic membrane. In the permeate stream (backside of the membrane), H2 will be used as a sweep gas, ideally resulting in N-H coupling reactions and subsequent ammonia synthesis. This technology allows for the Earth-abundant elements such as vanadium and niobium (and not precious metals) to be used as the primary metals for nitrogen dissociation and transport. Wilcox has demonstrated preliminary data for some of the separations and reactions through an earlier NSF EAGER project. The remaining large technical risk is in devising the membrane and reactor system which performs the separations and catalyzes all the reactions together at a useful rate. Broader Impacts Broader impacts of the results of the proposed work are many. This technology offers a route to carry out the ammonia synthesis process at atmospheric pressures, adding huge savings to the agricultural chemical industry. Fertilizers are one of the most important factors in securing sufficient global food production. Demand is guaranteed to increase, as it is directly proportional to world population increase. Through the application of selective-N2 membrane technology, ammonia could be produced at a lower energy cost than the traditional high-pressure Haber-Bosch process. In addition to the science- and technology-based broader impacts, the PI plans to incorporate results from this research into a Carbon Capture course she developed in the Energy Resources Engineering department at Stanford University. Wilcox serves as a female role model for women in science, exhibited by the high number of female undergraduate and graduate students she has mentored. The exciting potential in this project should serve as a further attraction to increase females in engineering disciplines. Further dissemination of the results of the work will take place through the PI?s participation in the summer school program, Research Experience for Carbon Sequestration, which is supported by the Office of Fossil Energy of DOE and hosted annually by Southern Company. The summer school provides students with hands-on experience regarding CO2 capture and storage, with additional hosts including Alabama Power and the National Carbon Capture Center, which supports the testing of early capture technologies at the pilot scale. The PI will present findings through a course offered in the summer school program each year throughout the duration of the award.