(363x) Regulating COx Thermal Catalytic Conversion through Catalyst Design and Reaction Energy Input

Developing and implementing cost-effective catalytic technologies to lower the chemical industry’s carbon footprints and ultimately empower successful transition to CO_X-free energy sources are the centerpiece of the ongoing industrial decarbonization research efforts. With thermal catalysis as the workhorse of the chemical industry, rational catalyst design strategies (to improve reaction and energy efficiency) and viable alternative heating techniques for thermal reactors are central to mitigating industrial CO_x emissions. With a particular interest in CO_x valorization and clean hydrogen transport and recovery, my Ph.D. research focused on regulating low-temperature thermal catalytic reactivities through rational catalyst design and reaction energy input.

Developing high-performance, low-temperature (< 400 ËšC) catalysts for the conversion of CO₂ to syngas, a versatile building block molecule for the chemical industry, is often challenged by the sluggish CO₂ activation or the overstabilization of CO that frustrates the overall catalysis. Downsizing the supported metal structure can regulate CO adsorption strength to prevent its over-hydrogenation to CH₄, but CO₂ adsorption/activation becomes compromised owing to the so-called Bronsted-Evans-Polanyi (BEP) linear scaling relationship. We developed a dual-site design strategy that overrides these paired constraints to enable low-temperature reverse-water-gas-shift activity via completely decoupled CO₂ and H₂ activation routes - infeasible with traditional metal oxide-based catalysts. Our mechanistic studies show that through the decoupled catalytic functions resulting from the synergistic interaction between Pt and α-MoC, the Pt₁/α-MoC catalyst rendered unusual reactivity via a unique bifunctional mechanism. The facile CO₂ activation and the subsequent desorption of *CO rely heavily on the MoC substrate, while the Pt₁ species is nearly exclusively preserved for H₂ activation. We further found that for typical performance-oriented catalysts where the support is also catalytic active to directly participate in the reaction - as with industrial catalysis -, the per-weight reactivity of single-atom catalysts may not be simply scaled up by arbitrarily increasing the population of the supported metal. Instead, the population of and interatomic distances between supported metal sites would be the critical overall catalytic performance descriptors.

As a recent advancement in reaction engineering, magnetic induction heating (MIH), where ferromagnetic nanoparticles are utilized as self-heating susceptors in the catalyst bed, is viewed merely as a scalable and energy-efficient alternative heating approach for thermal reactions. Specifically, when these magnetic nanoparticles are exposed to an alternating magnetic field (MF_alt), their unpaired electron spin/magnetic moments align in response to the field; when the field is reversed, the aligned electron spin switches direction. This rapid cyclic motion of electron spins converts electromagnetic energy from MF_alt to internal energy gains. However, does the internal energy gain fully translate to apparent heat or part of it can be infused into the intrinsic catalysis, since both the internal energy gain and catalysis originate from electron spin regulations? In our exploration of nominal thermal catalysis via MIH reaction mode, we found that coupled with proper catalysts, MIH can in addition to supplying heat, directly regulate thermal catalytic chemistry. With the typical ferromagnetic Pt/Fe₃O₄ nanocatalysts and CO oxidation reaction as a model system, we found MF_alt to be effective for regulating CO oxidation beyond temperature controls and new catalytic structure creation. Mechanistic studies suggest that MIH-driven thermal catalytic reactions benefit from the periodic electron spin regulations under an alternating magnetic field. This contrasting and beneficial field-enhanced thermal catalytic chemistry was also preliminarily observed for CO₂ reduction and ammonia decomposition reactions, potentially paving the way to launch MIH-triggered thermal catalytic reactions as a new reaction category. Therefore, contrary to the original perception that MIH is merely an alternative heating technique for thermal reactions, our preliminary research findings highlight the opportunity to leverage dynamic magnetic field as a new tuning knob to reimagine the otherwise static thermal catalysis.

Research Interests

With a strong background in heterogeneous thermal catalysis and reaction engineering, my research interests include but are not limited to the investigation and development of catalytic technologies for carbon emissions mitigation, clean energy and chemicals manufacturing as well as plastic upcycling etc. My overall career interest is to help chemical and allied manufacturing businesses develop and implement cost-effective catalytic technologies that foster sustainable chemical and energy manufacturing while maintaining their economic competitiveness.