Pelletized SiO2-supported La0.5Ba0.5FeO3 for conversion of CO2 to CO by a reverse water-gas shift chemical looping process

Abstract

Perovskite oxides, such as La0.5Ba0.5FeO3 (LBF), are promising materials for converting CO2 to CO through low-temperature reverse water–gas shift chemical looping (RWGS-CL). To transition toward industrialization, this study focused on forming perovskite-oxide/silica composite pellets (25 wt% LBF) with sufficiently high crushing strength, with materials prepared by extrusion and tableting methods. X-ray fluorescence (XRF) and diffraction (XRD) confirmed that the resulting material is 26.6 wt% LBF on SiO2 with a combined structure of LBF and SiO2 components. Temperature-programmed reduction (TPR) and oxidation (TPO) experiments revealed that CO2 is converted to CO at 550 °C by LBF/SiO2 pellets, higher than LBF by 50 °C. CO2 chemisorption was determined to be 62.2 μmol/gLBF. DRIFTS-MS experiments confirmed that adsorbed CO2 is dissociated to CO. High material stability is proven by long-term RWGL-CL experiments combined with XRD and XPS. The CO2 to CO yields were 2.21, 2.41, and 2.35 mmol/gLBF of 10 mm tableting pellets, 6 mm tableting pellets, and extrusion pellets, respectively. Deactivated pellets are able to be regenerated by air thermal treatment following intentional reduction. 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.