Novel perovskite ceramics for chemical looping combustion application

New modified calcium manganese (CM) perovskite structures applicable in chemical looping combustion were synthesized in this study. These modifications were applied by doping the A-site with lanthanum and strontium and B-site by iron and zirconium (CLMF, CLMZ, CSMF, and CSMZ). TGA, XRD, SEM and BET techniques have been used to characterize the prepared structures. According to the results obtained from TGA analysis, the oxygen capacity of the samples ranged between 1.2 for CLMZ and 1.75 for CSMF. All prepared samples showed to possess a porous surface and the perovskites phase formation was confirmed by XRD results. Iodometric titration experiments were also conducted for evaluating the manganese ion charge and its variability in association with different doping elements. Reactivity and oxygen uncoupling behaviors of the prepared samples were also evaluated using a fluidized bed chemical looping reactor using methane as the fuel at four different temperatures (800, 850, 900, 950 degrees C). All of the oxygen carriers showed oxygen uncoupling behavior and they were able to capture and release oxygen. Mass-based conversion of the perovskites was calculated and temperature increase proved to increase the mass-based conversion rate in all of the samples under study. Gas yield was calculated at 950 degrees C as well, and results showed that CLMZ, CM and CSMF showed 100% gas yields and CLMF and CSMZ showed approximately 85% yield in fluidized bed reactor, which is a high and acceptable quantity. (C) 2016 Elsevier Ltd. All rights reserved.