Integrated Experimental and Theoretical Endeavor for Fundamental Understanding of Processes in Methane Dehydroaromatization

The West Texas Permian Basin holds trillions of cubic feet of natural gas resources predominantly comprised of methane, which constitutes an economic opportunity in the billions of dollars to upgrade this low-carbon fossil fuel to higher-value fuels and chemicals. The project advances catalytic processing technology that upgrades methane to higher-value chemicals in small plants located at or near the production wells, thus avoiding flaring or costly gas pipeline transport. The catalysts currently employed in this process do not fulfill the activity and stability requirements necessary to make the process economically viable. The study integrates experimental and theoretical methods to better understand the factors limiting current catalyst performance, and uses that knowledge to guide the design of improved catalysts and processing schemes. The project also promotes training of graduate and undergraduate students in technologies related to efficient, cost-effective, and low environmental impact utilization of hydrocarbon resources, while promoting outreach to predominantly minority schools to attract K-12 students to STEM fields. This project targets methane dehydroaromatization (MDA) which constitutes a path for the direct conversion of methane to benzene and hydrogen. Specifically, the project focuses on ZSM-5-supported molybdenum (Mo) catalysts. Previous work by the investigators has revealed that the specific processes by which a ZSM-5-supported Mo oxide precursor is activated to form Mo carbide species strongly affects the catalytic behavior. Thus, Mo-C-support interactions play a pivotal role in achieving the stable formation of aromatics. To further investigate those interactions, model catalysts, with active metals existing only on either the outer surface or within the zeolite channels, will be prepared and evaluated by a suite of experimental and computational tools. The structure, location, and evolution of the Mo species will be monitored by in situ and operando experiments using advanced characterization techniques, including X-ray absorption and high-resolution powder diffraction. The experimental data will be combined with density functional theory calculations to advance knowledge with respect to the structure-activity relationship of the catalysts and the reaction pathways involved in the complete MDA catalytic cycle (activation, reaction, deactivation, regeneration). The combination of kinetic tests, in situ structural characterization, and theoretical calculations will result in the determination of the reaction and deactivation pathways of MDA and will provide the basis for the rational design of catalysts. Beyond the research efforts, the investigators will develop a novel virtual reality (VR) technology module that will allow K-12 students to immerse themselves into a catalyst structure and allow them to directly interact with dynamic 3-D images of the molecules involved in a catalytic process. 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.