Degree
Doctor of Philosophy (PhD)
Department
Chemical Engineering
Document Type
Dissertation
Abstract
Methane is the smallest hydrocarbon and the most abundant component in natural gas. Despite its availability, its chemical utilization has remained limited due to the challenges associated with direct methane activation and conversion. Most of the methane oxidation and oxidative carbonylation reactions in literature have been carried out at high-pressure using batch reactors or at ambient pressure using flow reactors. While batch reactors have been shown to have higher product yields, they are limited in their capability to provide real-time kinetic insights and comprehensive mechanistic understanding of the reactions involved due to the long residence time. This limits rationalization of catalyst designs for improving catalytic performance and possible process commercialization.
In contrast, continuous flow reactors allow for variable residence times and reactant partial pressures and thus offer a more robust platform for understanding reaction pathways in real-time. While continuous flow reactors have been employed to investigate methane partial oxidation reaction, most of these studies have been limited to near-ambient pressure operation. As a result, there exists a knowledge gap between high-pressure batch reactors and ambient-pressure flow reactors.
This dissertation describes our efforts to bridge this knowledge gap and investigates the conversion of methane into value-added oxygenates and products under high-pressure and relatively mild temperatures using continuous flow reactors. Chapter 2 demonstrates the conversion of CH4 and CO2 with C2H4 and O2 over Pd-Au/CeO2 at 200°C, producing propene, acetone, and methyl acetate. In situ DRIFTS confirmed the formation of methoxy adspecies on Pd-Au/CeO2 from CH4 and CO2, which is believed to be a reaction intermediate to methyl acetate.
Chapter 3 explores methane oxidative carbonylation over Rh/ZSM-5 catalysts with CH4, CO, O2, and steam cofeeding. Acetic acid and methanol are the major oxygenate products, with kinetic and methanol cofeed experiments indicating that the CH3 moiety of acetic acid originates from methane and the CO of the carboxyl group originates from carbon monoxide, with no evidence for methanol carbonylation.
In chapter 4, catalyst testing on Au/ZSM-5 catalysts synthesized using different methods revealed that larger Au nanoparticles favor the formation of oxygenates. Collectively, these studies provide evidence for low temperature methane activation and coupling and provide mechanistic insights for methane valorization catalyst design.
Date
7-12-2025
Recommended Citation
Aurnob, A K M Kazi F.M., "Low Temperature Methane Coupling with CO and CO2" (2025). LSU Doctoral Dissertations. 6858.
https://repository.lsu.edu/gradschool_dissertations/6858
Committee Chair
Ding, Kunlun
DOI
10.31390/gradschool_dissertations.6858