Bifunctionality of Intermetallic Pd-In/Indium-Oxide Catalysts for CO2 Hydrogenation to Methanol

University Of Florida, Gainesville FL

Investigators

Abstract

Developing catalytic processes to efficiently convert carbon dioxide (CO2) to chemicals and fuels is essential for mitigating CO2 emissions and enabling technologies that utilize renewable energy. The direct conversion of CO2 to methanol is particularly attractive because methanol can serve as a fuel in existing power generation systems and is used as a feedstock in the commercial-scale synthesis of a wide-range of important chemicals. Currently, however, catalytic processes to directly hydrogenate CO2 to methanol are unsuitable for commercial use. The major difficulty is that most catalytic materials lack the stability and activity to operate at the low temperatures needed for CO2-based methanol synthesis. In this project, the investigators are developing a fundamental understanding of the selective hydrogenation of CO2 to methanol using bifunctional metal/metal-oxide catalysts. Exploiting the distinct chemical functionality of the metallic and oxide components of these catalysts is necessary for efficiently and selectively converting CO2 to methanol. The investigators are providing opportunities for high school and undergraduate students to participate in their research and are focused on recruiting students from underrepresented groups to engage in these activities. These outreach activities seek to promote the science, technology, engineering and math (STEM) disciplines. The project aims to develop a fundamental understanding of Pd-promoted In2O3 (indium oxide) catalysts and determine how the chemical bifunctionality of these surfaces can be exploited to enhance the selective hydrogenation of CO2 to methanol. The key idea is that coexisting In2O3 and intermetallic PdxIny phases will act cooperatively to enhance the hydrogenation of CO2 to methanol by exchanging reaction intermediates and providing interfacial surface sites with unique chemical properties, and that the catalytic behavior can be modified by the PdxIny structure and stoichiometry. This research involves investigations of the structural and chemical properties of Pd-modified In2O3 prepared as planar crystalline surfaces as well as nanocrystalline powders. These materials are investigated using a combination of experimental and theoretical methods including ultrahigh vacuum surface science and catalyst characterization, reactor studies and operando surface spectroscopy, as well as density functional theory and microkinetic modeling. A primary aim of the project is to establish fundamental structure-function relationships to guide the design of Pd-In2O3 catalysts for the selective hydrogenation of CO2 to methanol. The project involves stringent comparisons of the results of first-principles modeling with experimental results obtained from planar crystalline surfaces and more complex nanoparticles to develop a robust understanding of the direct hydrogenation of CO2 to methanol. 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.