Computational Study of C-C Coupling Reactions on Heterogeneous Catalysts

Author

Md Saeedur Rahman, Louisiana State University and Agricultural and Mechanical CollegeFollow

Degree

Doctor of Philosophy (PhD)

Department

The Gordon A. and Mary Cain Department of Chemical Engineering

Document Type

Dissertation

Abstract

The utilization of carbon dioxide (CO₂) in chemical production has attracted global research interest. Reacting CO₂ with methane (CH₄) removes these greenhouse gases from the atmosphere and turns both compounds into building blocks for organic compound synthesis. A commonly explored pathway involves dry reforming of methane (DRM), which reacts CH₄ and CO₂ to form syngas, a mixture of H₂ and CO. Syngas is a widely used feedstock for synthesizing chemicals ranging from methanol to fuels via the Fischer-Tropsch (FT) process. However, DRM has a large positive ΔGº, which requires the reaction to be carried out at a high temperature (1000~1200 K) to achieve a favorable equilibrium constant. Therefore, DRM requires significant energy input, which contributes to instead of reducing greenhouse gas production. This research is focused on alternative routes for reacting CO₂ with CH₄ to avoid high energetic penalties. The fundamental premise is the formation of acetate (CH₃COO) species on catalyst surfaces as a key intermediate toward producing organic compounds such as vinyl acetate, alkyl acetates, acetic anhydride, and cellulose acetate, all of which are important industrial chemicals. We perform computational modeling based on first-principles density functional theory (DFT) calculations to generate atomic-level insights that guide the design of heterogeneous catalysts for catalyzing methane carboxylation by CO₂ (MCC) to form CH₃COO. We investigate three types of catalytic materials, including ceria, pure metals, and alloys, to identify the factors that determine the effectiveness of these materials. Based on the insights, we propose single-atom alloys (SAAs) by doping a late d-metal (Ni and Cu) with a small amount of a more reactive metal (Zr, Hf, and Co). The catalytic advantage of the SAAs stems from stabilizing the CH_x-CO₂ coupling step at the more oxophilic dopant site while the host metal activates CH₄. We also examine the functionalization of Cu by phenyl phosphonic acid (PPA) molecules to protect the metal surface from oxidation.

Date

1-11-2023

Recommended Citation

Rahman, Md Saeedur, "Computational Study of C-C Coupling Reactions on Heterogeneous Catalysts" (2023). LSU Doctoral Dissertations. 6033.
https://repository.lsu.edu/gradschool_dissertations/6033

Committee Chair

Xu, Ye

DOI

10.31390/gradschool_dissertations.6033