The recent advancements in fracking technology has led to an abundance of shale gas availability at low cost which has made methane conversion to value added chemicals a huge topic of interest. However, the high molecular stability of methane is a significant challenge to direct conversion of methane to chemicals and fuels. The conventional process for methane conversion is to first convert it to syngas which is used as a building block for other chemicals. This indirect approach requires multiple processing steps which are both energy and cost intensive. Oxidative Coupling of Methane (OCM), on the other hand, is a one step process towards producing higher hydrocarbons from methane. Traditionally, OCM has been carried out by co-feeding molecular oxygen with methane over a catalyst. The chemical looping method, however, utilizes the lattice oxygen in a catalytic oxygen carrier (COC) for methane oxidation. A Mg6MnO8-based COC was studied to gain mechanical insights into OCM carried out using the chemical looping method. Density functional theory (DFT) calculations were used to determine the mechanism where lattice oxygen diffusion and vacancy formation were particularly focused upon. These calculations were corroborated with multiple reduction and oxidation (redox) cycles with methane and air, respectively, conducted in a fixed bed reactor. COC characterization for both the oxidized and reduced forms was done using X-ray diffraction (XRD), X-ray spectroscopy (XPS) and Scanning Electron Microscopy (SEM). Computational screening of dopants for Mg6MnO8-based COC using DFT was done with the objective of increasing the selectivity towards higher hydrocarbons.

Role of oxygen vacancies in oxidative coupling of methane over Mg6MnO8-based catalytic oxygen carriers in a chemical looping system

255th National Meeting (2018)

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