Ca/Al doped lanthanum manganite perovskite coated porous SiC for CO₂ conversion

Abstract

Reticulated porous ceramics (RPCs) have promising potentials as substrates in catalytic reactions where higher surface area is favorable. In this paper, we investigate the CO2 conversion efficiency of calcium and aluminum doped lanthanum manganite – LCMA (La₀.₆Ca₀.₄Mn₀.₆Al₀.₄O₃±δ) perovskite. The LCMA perovskite coats the surface of an RPC to maximize available reactive surface in reduction-oxidation (redox) reactions. We provide a robust approach in synthesis and characterization of the LCMA, RPC and the coating process through x-ray micro computed tomography (XCT), x-ray diffraction (XRD) and scanning electron microscopy (SEM) imaging. Our results show the presence of a dual pore size distribution in the RPC with the larger pores forming a connected network and smaller ones within struts. We show that the LCMA coated RPC is capable of converting CO2 to carbon monoxide ([CO%] = 3.2) when exposed to 10 vol% CO₂ feed gas (at 1050 °C) after ~1.5 h of reduction reaction at 1240 °C. The XCT characterization shows that the redox conditions affect the RPC in two ways: i. distortion of the RPC structure and the removal of smaller pores. ii. the LCMA layer migration into the RPC framework resulting in the reduction of the specific surface area between coating and porous network.