CAREER: In-situ Capture and Conversion of CO2 to Hydrocarbons

University Of California-Riverside, Riverside CA

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Over the past decades, global emissions of greenhouse gases, carbon dioxide (CO2) and methane (CH4), have risen steadily, thus creating an urgent need for technology capable of capturing and/or converting those molecules to higher-value chemicals. The project investigates the effectiveness of perovskite materials to serve the dual function of capturing CO2 and catalyzing its conversion to hydrocarbons by reaction with CH4. Specifically, the aim is to tune the perovskite composition to promote efficient capture of CO2, followed by reaction with CH4, to produce syngas, ethane, and ethylene - all of value as essential platform chemicals that can be readily converted to polymers and fuels. Thus, the project explores a novel approach to achieving the simultaneous goals of mitigating greenhouse gas emissions while securing future supplies of energy and chemical raw materials. The project integrates the research with an education and outreach plan introducing students to sustainable engineering precepts, while broadening and diversifying the future science and engineering workforce. The project investigates structure-composition-function properties of sorption-enhanced perovskite oxide catalysts for hydrocarbon synthesis via either dry methane reforming (DRM) or CO2-mediated oxidative coupling of methane (CO2-OCM). Specifically, the project focuses on SrTiO3 and CaTiO3 given their inherent basicity (which promotes the adsorption of CO2), combined with their capability to activate CO2 and CH4 using oxygen vacancies. Preliminary studies by the investigator have determined that the SrTiO3-based multifunctional catalysts, doped with Ni, can capture CO2 and convert it to syngas, ethane, and ethylene. The project will use SrTi1-xMxO3/SrO or CaTi1-xMxO3/CaO (with M=Ce, Mn and x = 0 – 0.1) systems to selectivity adsorb CO2 from simulated ideal or flue gas mixtures. Specific goals include: (1) elucidating the transport and reaction kinetics for CO2 capture and release in air and flue streams, (2) evaluating the effects of dopant metals on the kinetics, selectivity, and stability of the multifunctional catalysts under reaction conditions, and (3) enhancing the surface area of the perovskite-based catalysts by synthesizing them on monolith supports, and 4) ensuring the stability of the catalysts by investigating cyclic operation to periodically regenerate the catalysts due to metal-dopant exsolution, and/or perovskite structure destabilization under reaction conditions. The project utilizes a broad range of characterization and evaluation techniques, highlighted by in situ and operando high-pressure/high-temperature FTIR and Raman spectroscopic characterization of adsorbed surface species (FTIR) and oxygen vacancies (Raman), the latter in collaboration with Dr. T. J. Kim at Stony Brook University. Integration of the research with educational and outreach initiatives focuses on sustainable engineering concepts related to chemical engineering, particularly with respect to improving the inclusiveness of women in the chemical engineering field. Efforts along those lines will be incorporated into well-established education and outreach programs for underrepresented students at the investigator’s institution. Specifically, the investigator plans to 1) start an annual graduate preparation retreat program for first-year graduate women in engineering, 2) develop research experience for undergraduate women and transfer students, 3) develop hands-on engineering activities for K-8 girls to solve environmental problems, and 4) expand undergraduate and graduate chemical engineering course curricula. 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.