CAREER: Harnessing the Power of Dynamic Magnetic Field to Reimagine Thermocatalytic Ammonia Decomposition

About This Grant

Many of our manufactured chemical products and fuels derive from fossil-based resources such as natural gas and petroleum, which also serve as our primary source of energy via combustion, thereby contributing to greenhouse gas emissions. Natural gas and petroleum consist of molecules with varying amounts of carbon and hydrogen. While this is convenient for chemical manufacturing of hydrocarbon products such as plastics, fibers, and construction materials, it does not fit well with green chemical processing where the products must be built from renewable carbon materials (such as biosources) and hydrogen produced from the splitting of water molecules via renewable energy sources such as solar or wind. While fossil sources come with the carbon and hydrogen already molecularly linked, production of chemicals from biosources or captured carbon often requires transport of hydrogen from small-scale, highly distributed sources. Because of the inherent challenges in transporting gaseous hydrogen, this has created a need for so-called liquid carrier molecules that are rich in hydrogen and can be readily shuttled to distributed chemical plants where the carrier molecules can be decomposed on-demand to generate hydrogen to react with carbon resources. Ammonia (NH3) is one such carrier molecule. The focus of the project is on efficient catalytic decomposition of NH3 to support low-carbon chemicals and fuels production. To that end, a key thrust of the project is to explore the use of magnetic induction heating (MIH) to provide the energy needed for hydrogen release. MIH can be driven by sustainably produced electricity, thus offering a carbon-free alternative to fossil-fuel process energy. The overarching project goal is to understand how operating magnetic induction heater in a dynamic magnetic field (DMF) mode, with varied field strength H and switching frequency f, enables the modulated spin polarization of the catalytic atoms in representative Fe-based ferromagnetic catalysts, thereby achieving overall high reactivity in NH3 decomposition and stability against nitridation. NH3 decomposition kinetics wrestle with the well-known Sabatier limit, which centers around the binding strengths of the *N-based species. Among the elementary reaction steps, the first *N-H bond scission (to produce H2) and the associative desorption of the dehydrogenated *N (to produce N2) are characterized by competing energetics. In a “static” thermal reaction where a catalytic metal has a single spin state, favoring one of the above two steps will inevitably disfavor the other. The study is built on the hypothesis that by leveraging the DMF in the MIH reaction mode, two-state catalytic centers featuring low and high polarized states can be created periodically at high frequencies, thereby becoming kinetically favorable for both *N-H scission (for strong N-atom catalyst binding) and associative *N desorption (for weak N-atom catalyst binding), thus inducing a “dynamic” chemically-enhanced thermal reaction. The research will begin with developing Fe/MgO catalyst platforms for comparative studies in thermal and MIH reaction modes. The findings from the Fe/MgO system will build toward exploring M-Ox-Fe variants (M= Co, Ru, Pd) to probe distinctive outermost d-orbital structures for modulating the spin polarization. The experimental investigations will center around how the catalysts respond to the dynamic magnetic field from kinetics, binding behaviors, and catalytic atom properties - benchmarking to standard thermal reactions. Lab-based kinetic studies will be extended to embrace catalyst synthesis variations (e.g., particle size), MIH studies under static and dynamic conditions, and computational studies conducted by collaborators at Clemson University, Oak Ridge National Laboratory, Argonne National Laboratory, and Tulane University. Through integrated research and educational initiatives, the project entails a suite of “Fail Forward” student training components in the context of electric field enhanced reactions, which build upon standard thermal reaction knowledge and serve as a gateway to encourage students to step outside their knowledge comfort zones to embrace ever-evolving science, and thus develop autonomy for lifelong learning. The project will reach 500+ students annually from grades 6 to the graduate level to accelerate the development of the future engineering workforce in South Carolina and beyond. 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.