Synthesis and optimization of NixMn1-xFe2O4 catalyst in chemical looping steam methane reforming process

The NixMn1-xFe2O4 oxygen carrier is synthesized through the chemical precipitation method to be applied in the chemical looping steam methane reforming process (CL-SMR). The response surface method (RSM) is adopted based on the central composite design (CCD) model to evaluate the effect of the independent variables on the responses’ functionality and to predict the best response volume. The variables: reaction temperature (550-750°C), oxygen carrier (OC) loading rate (0.1-0.9), steam per methane ratio (S/C) (1.5-3.5), oxidation-reduction cycles’ count (1-9) and the responses consisting of CH4 conversion percentage, CO/CO2 molar ratio and H2 production yield are assessed. The analysis of variance (ANOVA) results indicates that reaction temperature and the OC type are the most effective, while the oxidation-reduction cycles’ count is the least effective on CH4 conversion percentage and H2 production yield. By implementing the optimized results in laboratory conditions, it is revealed that the Ni0.6Mn0.4Fe2O4 OC at operating conditions at 650°C, S/C=2.5 and 9 redox cycles, the best response to the CH4 conversion percentage, CO/CO2 molar ratio, and H2 production yield with 99.6, 15.7 and 77.6, respectively. The improved stability and functionality of the OC reveal that during the 24 redox cycle the self-supported Ni0.6Mn0.4Fe2O4 OC is of high stability, high CH4 conversion percentage means, and high H2 production yield. The OCs samples are characterized by applying FT-IR, XRD, FESEM with X-ray spectroscopy EDX, BET, and TGA.