(2ay) Sustainable Catalysis for Carbon Waste Valorization: Integrating System and Molecular-Level Approaches

Since the discovery of fossil fuels, the dependency of our industrialized world on fossil fuels has been increasing which brings up the challenges in energy and environment including environmental pollution, resource depletion, and energy insecurity. Converting carbon waste to renewable fuels and chemicals can potentially address the urgent sustainability challenges. My future research group will focus on catalytic technologies that upgrade carbon waste including waste plastics, biomass, and CO₂-based feedstocks to value-added, renewable products combining fundamentals and applications of sustainable catalysis. To evaluate and develop such technologies, we will characterize the substrates and products, validate the proposed technology, and assess their economic and environmental impacts. In selected routes, fundamental insights will be provided through the integration of advanced materials synthesis, catalysts characterization, and elucidation of the reaction mechanisms using kinetic and spectroscopic measurements, enabling the development of catalysts that exhibit enhanced efficiency and selectivity. A comprehensive understanding from both the system and molecular-level will facilitate the development of the catalytic processes tackling challenges in carbon waste upgrading.

Doctoral research (Washington State University; Advisor: Yong Wang)

My doctoral research centered around elucidating reaction mechanisms and site requirements in the production of olefins from biomass-derived feedstocks. I revealed how metal-support interfaces mediate the reaction pathway of ethanol-to-butadiene conversion [1]. Using an in-operando Diffuse Reflectance Infrared Fourier Transmission Spectroscopy-Mass Spectroscopy system, I investigated the reaction pathway of acetone C-C coupling as well as the decomposition of acetone oligomers, producing olefins [2-3]. The crucial roles of water in the biomass upgrading were uncovered with in-situ characterization, isotopic labeling, reaction kinetics, and density functional theory [4]. The investigation of the reaction mechanism unraveled the precise molecular-level site requirements concerning Lewis acid-base pairs on faceted metal oxides [5], paved the way for the development of a novel material with desirable stability [6].

Postdoctoral Research (University of Wisconsin-Madison; Advisor: George Huber)

My postdoctoral research focuses on recycling and upcycling of waste plastics at the Chemical Upcycling of Waste Plastics (CUWP, www.cuwp.org) center. I summarized the entire life cycle of plastics [7] and led a study that showcased the potential of upgrading pyrolysis oils derived from post-consumer recycled polyolefins to yield high-value chemicals with a substantial market value ranging from $1600 to $5000 per ton. This route has proven to be a promising platform technology, achieving a 60% reduction in greenhouse gas emissions compared to their production via petroleum feedstocks, and has been recently recognized in Science [8]. By adopting a system-level mindset, I thoroughly characterized challenging substrates and products and analyzed the pyrolysis oil upgrading system.

Teaching Interests

My primary objective as an educator is to empower students to not only acquire knowledge but also to effectively apply that knowledge in practical problem-solving scenarios. To me, mentoring is able to motivate students in all streams to improve their engagement, enjoyment, achievement levels, and their attitude towards lifelong learning. With my background in chemistry, chemical engineering, and heterogeneous catalysis, I am prepared to teach core chemical engineering courses. I am particularly interested in teaching courses in reaction engineering, kinetics, thermodynamics, as well as process design. I am also excited to develop elective courses focused on waste plastics recycling/upcycling, building upon the research and insights gathered in my review paper [7]. This paper details the current state of the plastics recycling industry and includes other emerging technologies that could serve as a comprehensive textbook on the subject. I have numerous teaching and mentoring experiences during my doctoral and postdoctoral study including serving as a teaching assistant for both undergraduate and graduate level courses, as well as providing guidance and mentorship to over 10 researchers spanning the undergraduate, graduate, and postdoctoral levels.

I am deeply committed to fostering diversity, equity, and inclusion in both my teaching and mentorship roles. Presently, I am actively engaged with multiple students and principal investigators from underrepresented groups within the CUWP center. Additionally, I had the privilege of co-chairing the 7th University of Wisconsin-Madison Postdoctoral Research Symposium, which provided me with invaluable opportunities to collaborate with individuals from diverse backgrounds. Going forward, I am determined to encourage, embrace, and support individuals with diverse backgrounds to join my group. I strive to create an inclusive environment where every member of my team and each class participant feels heard, respected, and valued.

References

(Complete publications at https://scholar.google.com/citations?user=I4fuGN8AAAAJ&hl=en&oi=ao)

[1] Li, H.^✝, Pang, J.^✝, Jaegers, N. R., Kovarik, L., Engelhard, M., Savoy, A.W., Hu, J., Sun, J., Wang, Y. “Conversion of Ethanol to 1, 3–Butadiene over Ag–ZrO2/SiO2 Catalysts: The Role of Surface Interfaces.” Journal of Energy Chemistry, 54 (2021), 7-15. ^✝Equal contributions.

[2] Li, H., Sun, J., Wang, Y. “Surface Acetone Reactions on ZnxZryOz: A DRIFTS-MS Study.” Applied Catalysis A: General, 573 (2019): 22-31.

[3] Li, H., Sun, J., Li, G., Wu, D., Wang, Y. “Real-Time Monitoring of Surface Acetone Enolization and Aldolization.” Catalysis Science & Technology, 10(4) (2020), 935-939.

[4] Li, H., Guo, D., Ulumuddin, N., Jaegers, N. R., Sun, J., Peng, B., McEwen, J.S., Hu, J., Wang, Y. “Elucidating the Cooperative Roles of Water and Lewis Acid–Base Pairs in Cascade C–C Coupling and Self-Deoxygenation Reactions.” JACS Au, 1(9) (2021), 1471-1487.

[5] Li, H., Hurlock, M. J., Sudduth, B., Li, J., Sun, J., Zhang, Q., Wang, Y. “Acetone to Isobutene Conversion on ZnxTiyOz: Effects of TiO2 Facet.” Journal of Catalysis, 410 (2022), 236-245.

[6] Li, H., Hu, W., Pang, J., Cabalera, V., Sun, J., Kovarik, L., Hu, J., Ni, Y., Wang, Y. “Confined Dual Lewis Acid Centers for Selective Cascade C-C Coupling and Deoxygenation.” Submitted

[7] Li, H., Aguirre-Villegas, H. A., Allen, R. D., Bai, X., Benson, C. H., Beckham, G. T., ... Huber, G. W. “Expanding Plastics Recycling Technologies: Chemical Aspects, Technology Status and Challenges.” Green Chemistry, 24 (2022), 8899-9002.

[8] Li, H., Wu, J., Jiang, Z., Ma, J., Zavala, V. M., Landis, C. R., Mavrikakis, M., Huber, G. W., “Hydroformylation of pyrolysis oils to aldehydes and alcohols from polyolefin waste.” Science, Accepted.