Study of H* spillover effect on a metal oxide support using both H2-TPR and FTIR spectroscopy
Research Poster Engineering 2025 Graduate ExhibitionPresentation by Mohammad Hamidizirasefi
Exhibition Number 132
Abstract
Hydrogen (H2) is crucial in chemical industries, making its activation on metal-oxide catalysts highly significant. Hydrogen spillover, where activated hydrogen species (H*) migrate from a hydrogen-rich active site to the support surface, is important in catalytic processes like hydrogenation and dehydrogenation. However, its practical application is limited due to challenges in characterization and quantification. Our recent studies on Au/TiO2 catalysts demonstrated that in situ FTIR spectroscopy combined with volumetric chemisorption can detect H* transport. Building on this, we investigated the Au-MnOx/TiO2 catalyst system using H2-TPR and in situ H2-FTIR spectroscopy to examine H* supply and MnOx reduction kinetics via hydrogen spillover. Metal-oxide reduction using H* spillover involves three step H2 dissociation, spillover, and H2O formation. MnOx typically exhibits low H activation at low temperatures by itself, while our findings show that H* spillover from the Au-TiO2 interface enhances MnOx reduction, significantly lowering the reduction temperature to room temperature and decreasing the apparent activation energy. The data suggests that H* is readily available on the Au/TiO2 surface at room temperature, with its presence dependent on the Au-to-MnOx ratio. These findings, confirmed through in situ FTIR spectroscopy, provide insights into the role of hydrogen spillover in catalytic systems and its potential for improving metal-oxide reduction processes.
Importance
Understanding hydrogen spillover on metal-oxide catalysts is crucial for enhancing catalytic reactions. This phenomenon can overcome kinetic and thermodynamic limitations, yet its practical application remains limited due to challenges in characterization. Our study on the Au-MnOx/TiO2 catalyst system reveals that H* spillover significantly lowers MnOx reduction temperature and activation energy, demonstrating its role in improving catalyst efficiency. Additionally, we confirm that H* is available on Au/TiO at room temperature, offering new possibilities for catalyst optimization. These findings contribute to the development of energy-efficient catalytic systems, with implications for sustainable chemical production, catalyst design, and hydrogen storage. By advancing the understanding of hydrogen spillover, this work helps drive the design of more effective catalysts for industrial applications.