CAS: Fundamental Experimental-Theoretical Investigations of New Metal Alloy Nanocatalysts for Natural Gas Repurposing

University Of Texas At Austin, Austin TX

Investigators

Abstract

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Profs. Simon M. Humphrey and Graeme Henkelman at the University of Texas at Austin are leading a highly collaborative research program involving the synthesis and reactivity studies of nano-sized alloys capable of converting methane into stable liquid fuels such as methanol, at the location where the methane is released. Meanwhile, natural gas flaring is an increasingly significant environmental issue worldwide and particularly in the USA. Natural gas (i.e., methane) that is released at oil recovery sites or in refineries is remediated by direct combustion to give carbon dioxide. While methane is a much more powerful greenhouse gas than carbon dioxide, the act of flaring still wastes the methane and adds millions of tones of extra carbon dioxide into the atmosphere each year. This is because compression of methane for transportation and eventual use is not cost-effective. This research project is fundamental and aims to understand how certain compositions of alloys of non-precious metals can perform the target reactions in a controlled and desirable manner. The scientific project is also significantly enhanced through integration with an innovative undergraduate educational program, called the Austin-International Framework (AIF), which provides a fully immersive, scholarship-supported international exchange experience to UT Austin undergraduates. It provides students the unique opportunity to broaden their horizons, while simultaneously earning course credit for their research experiences. This a collaborative experimental-computational research program between the groups of Profs. Simon M. Humphrey and Graeme Henkelman at the University of Texas at Austin. The overarching aims are to leverage expertise in the formation of novel metallic nanoalloys via microwave-assisted heating techniques, and to use theory in silico to guide synthetic studies and to elucidate the resulting reactivity of the nanoparticle catalysts, as a function of surface structure and composition. The specific goals of this project are to prepare new binary and ternary catalysts using combinations of catalytically less valuable and abundant coinage metals along with more highly oxophilic metals such as Ru and Re, to generate systems that can mimic the reactivity of scarcer noble metals. In addition to model gas-phase chemical reaction studies that mimic realistic reaction conditions, structure-function relationships will be elucidated using a palette of spectroscopic techniques (e.g., electron microscopy, total X-ray scattering, extended X-ray fine structure, chemisorption, etc.), to provide realistic theoretical models at the atomic scale. This structural information will then be used to build and refine theoretical models that can identify then most important active site ensembles. Ultimately this enables accurate predictions of reactivity and selectivity, which can be leveraged to inform future synthetic targets, toward the identification of eventual catalysts with desired reactivity: those that are able to selectively activate CH4 to CH3 and H in the presence of atomic oxygen. 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.