(280e) From Powder to Pellet: A Study of La1-XBaxFeO3 for Low-Temperature CO2 to CO Conversion By a Reverse Water-Gas Shift Chemical Looping Process

Reverse water-gas shift chemical looping (RWSG-CL) is a two-step process to convert carbon dioxide to carbon monoxide at a moderate temperature with high selectivity. In this research, perovskite oxides materials, La_1-xBa_xFeO₃ (LBF, x = 0.25 - 0.75), were explored for enhancing CO yield while maintaining stability over multiple cycles. Then, the SiO₂-supported LBF (LBF/SiO₂) was synthesized to further enhance the conversion yield. LBF/SiO₂ pellets formed by tableting and extrusion methods were revealed the conversion properties. Density functional theory (DFT) was utilized to calculate the oxygen vacancy formation energies (E_vac), identifying the E_vac of La_0.5Ba_0.5FeO₃ (3.0 eV) is in the ideal range of 3.4 ± 0.5 eV. Meanwhile, the reaction mechanism was revealed by combined methods of DFT and diffuse reflectance infrared Fourier transform spectroscopy (DRFITS). For all samples, XRD confirmed cubic perovskite structure, and XRF analysis established the precise composition. The reaction temperature, approximately 550^oC, was determined through temperature-programmed experiments. High material stability was proven by long-term RWGL-CL experiments combined with XRD. The CO₂ to CO yields were calculated in these experiments as 2.21, 2.41, and 2.35 mmol/g_LBF of 10 mm tableting, 6 mm tableting, and extrusion pellets, respectively. All pellets showed stable redox properties in 50 cycles of semi-batch reactor experiments, indicating that LBF/SiO₂ pellets are candidate materials for further scale-up evaluation.