(546y) CO2 Utilization in a Chemical Looping System for Methane Conversion to High Purity Syngas Using an Iron Based Composite Metal Oxide

Carbon management strategies such as CO₂ utilization to value added products is proving to be a key technology. Chemical looping technology for complete combustion of fuels has been well known in literature for producing CO₂ which is sequestration ready. On the other hand, high purity syngas can be produced by employing a novel co-current moving bed configuration in the chemical looping system which has been well understood on iron-titanium composite metal oxide (ITCMO). Due to ITCMO’s inherent thermodynamic capabilities, it can process CO₂ as a feedstock for methane reforming, thus converting it to an easily disposable product, syngas. This system has been previously investigated from a thermodynamic and process design standpoint, but the reaction mechanism for CO₂ utilization over ITCMO is yet to be explored.

Thermodynamically, the solid phase of FeTiO₃ is calculated to be in equilibrium with high purity syngas, thus making this solid phase the primary metal oxide for this study. Experiments on thermogravimetric analyzer (TGA) gave insights on the metal oxide conversion under reduction with methane co-fed with CO₂. Differential fixed bed experiments were also performed to understand the gas phase composition which was measured using a micro-gas chromatography analyzer. Solid characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to understand the changes in the solid phase. These experimental results will help guide the computational analysis in developing the mechanism. Oxygen vacancy interaction mechanism was carefully analyzed using atomistic thermodynamic methods and DFT calculations and compared against the experimental data. The mechanism thus developed will give a better understanding of CO₂ utilization in this novel process, thus providing a pathway to improve the utility of this technology.