Fischer-Tropsch synthesis (FTS) is a widely employed chemical manufacturing process, primarily used to convert steam-reformed natural gas to long-chain hydrocarbons or organic molecules suitable for fuels, lubricants, and other chemical products. The FTS reaction is typically run at high pressures where the catalyzed reaction between carbon monoxide (CO) and hydrogen (H2) is favored. Such high pressures demand extremely large reactors and associated chemical plants to achieve the economies of scale needed for cost-effective manufacturing. The project investigates an alternative approach to FTS in which the catalyst properties are tuned to promote reaction at lower pressures. The lower pressures, in turn, potentially open the door to cost-effective FTS in smaller scale plants that can be located close to remote or stranded sources of natural gas or distributed sources of renewable biomass. A key benefit of low-pressure, distributed FTS resides in its capability to ensure security in chemical manufacturing as our nation transitions to net-zero carbon emission technologies for manufacturing fuels and chemicals.

The project explores Electronic Metal-Support Interactions (EMSI) through the central hypothesis that a basic support will inject electron density into the metal clusters supported on them, and this electron donation will, in turn, result in stronger binding of CO onto the surface of the metal. Specifically, the investigators will synthesize and evaluate ruthenium (Ru) and cobalt (Co) catalysts supported on mixed metal oxides of the general formula MgxAlyO. The Mg:Al ratio will control the basicity of the supports and, in turn, the extent of electron donation into the supported Co and Ru. Changes in the electronic structure of the metals will be monitored by L-edge X-ray absorption spectroscopy (XAS). The experimental data (including direct assessment of CO binding strength via Fourier Transform Infrared Spectroscopy (FTIR) and CO temperature-programmed desorption (TPD)) will be validated with density functional theory (DFT) calculations and Bader analysis to confirm metal/support and adsorbate effects on the electron structure and charge transfer. The characterization and computational analyses will be followed by kinetic studies of the FT reaction under realistic operating conditions in a laboratory reactor. More broadly, the project will potentially lead to economic benefits for the U.S. by reducing capital and operating expenses for stranded natural gas upgrading to liquid fuels. The project will also train graduate, undergraduate, and high-school students in aspects of catalysis as related to chemical process engineering.

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.