Understanding and predicting the performance of metal exchanged SSZ-13 zeolite in the conversion of methane to methanol

巨大的页岩气储量现在正在全球范围内被开采。页岩气主要是甲烷，运输困难，价值相对较低。将甲烷转化为更高价值的产品，如甲醇，需要新的和改进的催化过程。甲醇是一种平台化学品，现有技术可以将其转化为各种有用的重要产品。金属交换沸石是一类具有广阔应用前景的甲烷合成甲醇催化剂。然而，这些催化剂是如何工作的还没有被很好地理解。此外，它们的催化性能依赖于许多复杂的参数，这些参数很难优化。在这个项目中，威斯康星大学的马夫里卡基斯博士正在通过理论和实验来了解一种特殊的沸石结构SSZ-13在将甲烷转化为甲醇方面的性能。他的工作是建立沸石合成条件和得到的SSZ-13的化学成分之间的关系，以及它的催化性能和反应条件之间的关系。所得结论将用于设计实验合成方案，以生产理想的甲烷转化为甲醇的沸石催化剂和反应条件。在这个项目中，Mavrikakis博士向公众介绍了理论建模在基础和工业研究与实践中的重要性。Mavrikakis博士还在教育本科生向初中生和高中生传授科学知识，并为本科生提供实习机会，让他们在他的团队中进行研究。在化学系化学催化项目的资助下，威斯康星大学麦迪逊分校的Mavrikakis博士正在应用理论和实验相结合的方法，了解使用过渡金属交换的SSZ-13沸石将甲烷转化为甲醇的基本原理。这包括：(I)通过建立合成参数(如模板和存在的离子的一致性)与所获得的沸石结构(如局部Al分布和缺陷密度)之间的相关性，对沸石合成进行第一性原理模拟；(Ii)对不同过渡金属(铜、铁、钴、镍)的相图和各种操作条件下的活性中心类型进行从头算计算；以及(Iii)计算最稳定的活性催化中心的反应路径。在接下来的步骤中，这些信息将被用于制定一项协议，用于实验合成、元素组成和反应条件，以使理想的金属交换SSZ-13沸石在甲烷转化为甲醇的过程中发挥最大性能。与此同时，与威斯康星化学教育研究所合作，马夫里卡基斯博士的团队正在开发模块，向本科生和中学生传授分子层面的思维如何带来新的强大技术。此外，P.I.还参与了威斯康星大学麦迪逊分校的本科生研究体验计划，该计划为本科生研究人员提供实践研究经验，重点是女性学生和来自代表性不足群体的学生。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。

Vast reserves of shale gas are now being accessed around the globe. Shale gas is mostly methane, which is difficult to transport and of relatively low value. The conversion of methane into higher value products, such as methanol, requires new and improved catalytic processes. Methanol is a platform chemical, with existing technologies for transforming it into a variety of useful, important products. Metal exchanged zeolites are a class of materials showing great promise as catalysts for transforming methane to methanol. However, how these catalysts work is not yet well-understood. Further, their catalytic performance depends on many complex parameters which are difficult to optimize. In this project, Dr. Mavrikakis of the University of Wisconsin is using both theory and experiments to understand the performance of one specific zeolite structure, known as SSZ-13, for the conversion of methane to methanol. His work is developing a correlation between zeolite synthesis conditions and the resulting chemical composition of SSZ-13, and between its catalytic performance and reaction conditions. The insights gained are being used to design experimental synthesis protocol to produce the ideal zeolite catalyst and reaction conditions for methane conversion to methanol. During this project Dr. Mavrikakis is informing the public about the importance of theoretical modeling in fundamental and industrial research and practice. Dr. Mavrikakis is also educating undergraduate students about communicating science to middle school and high school students, as well as providing internships to undergraduate students to conduct research in his group.With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Mavrikakis at the University of Wisconsin - Madison is applying a combined theoretical/experimental approach for understanding the fundamentals of converting methane to methanol using transition metal exchanged SSZ-13 zeolite. This includes: (i) first-principles modeling of zeolite synthesis through the development of correlations between synthesis parameters, such as the identity of template and ions present, and the obtained zeolite structure, such as the local Al distribution and defect density; (ii) the ab-initio calculation of phase diagrams for different transition metals (Cu, Fe, Co, Ni) and types of active sites for a wide range of operating conditions, and (iii) the calculation of reaction pathways for the most stable active catalytic sites. In a subsequent step, this information is being used to develop a protocol for the experimental synthesis, elemental composition and reaction conditions for maximized performance of the ideal metal exchanged SSZ-13 zeolite for the conversion of methane to methanol. In parallel, and in collaboration with the Wisconsin Institute for Chemical Education, Dr. Mavrikakis' group is developing modules to teach undergraduate and middle school students how thinking at the molecular level can lead to new powerful technologies. Furthermore, the P.I. is participating in the Research Experience for Undergraduates program at UW Madison, which is providing hands-on research experiences to undergraduate researchers with a focus on female students and students from underrepresented groups.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.