The influence of water on hydrogen spillover rates and catalytic consequences

The production of fuels, plastics, pharmaceuticals, and many other important chemicals depends on catalysts that activate hydrogen. Improving the catalyst performance is essential for lowering chemical manufacturing costs and strengthening U.S. energy security. When hydrogen reacts on a solid catalyst, it moves across the surface in a process called hydrogen spillover. Hydrogen spillover plays a critical role in many catalytic reactions, but the factors that control spillover are not well understood. This project will combine experiments with computational modeling to understand how hydrogen moves across catalyst surfaces. It will also study how catalyst surface structure and small amounts of water impact spillover. This will guide future catalyst design to take advantage of spillover. These advances will support improved technologies for petroleum refining and energy-related chemical processes. The project will also provide interdisciplinary research training for undergraduate and graduate students to help build a highly skilled U.S. workforce. It will engage high school students with hands-on energy and catalysis outreach activities. The project will establish quantitative relationships between catalyst structure, hydrogen spillover kinetics, and catalytic performance. Two important classes of support materials will be studied: carbon materials and reducible metal oxides. The project will integrate experiments and first-principles theoretical modeling to create model catalyst systems. Well-defined experimental and computational catalytic domains will be spatially separated. Hydrogen transport rates will be measured under controlled reaction conditions and compared to theory. This will allow the researchers to distinguish between hydrogen dissociation on metal surfaces and heterolytic activation at metal-support interfaces. The work will then identify the kinetically relevant elementary spillover steps. This will allow the team to determine how defects, oxygen-containing functional groups, and water influence hydrogen transport. The resulting kinetic framework will then be applied to increasingly complex catalyst architectures. Several representative carbon-carbon and carbon-oxygen bond cleavage reactions will be evaluated. By quantitatively connecting hydrogen migration to catalytic reactivity, the project will establish fundamental design principles for controlling hydrogen spillover. This will advance the broader fields of heterogeneous catalysis, chemical engineering, and surface chemistry. 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.