Synthesis and Optimization of NixMn۱-xFe۲O۴ Catalyst in Chemical Looping Steam Methane Reforming Process

The NixMn۱-xFe۲O۴ oxygen carrier is synthesized through the chemical precipitation method to be applied in the Chemical Looping Steam Methane Reforming (CL-SMR) process. 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 (۵۵۰-۷۵۰°C), Oxygen Carrier (OC) loading rate (۰.۱-۰.۹), steam per methane ratio (S/C) (۱.۵-۳.۵), oxidation-reduction cycles’ count (۱-۹), and the responses consisting of CH۴ conversion percentage, CO/CO۲ molar ratio, and H۲ 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 CH۴ conversion percentage and H۲ production yield. By implementing the optimized results in laboratory conditions, it is revealed that the Ni۰.۶Mn۰.۴Fe۲O۴ OC at operating conditions at ۶۵۰°C, S/C=۲.۵, and ۹ redox cycles, the best response to the CH۴ conversion percentage, CO/CO۲ molar ratio, and, H۲ production yield with ۹۹.۶, ۱۵.۷, and ۷۷.۶, respectively. The improved stability and functionality of the OC reveal that during the ۲۴ redox cycle the self-supported Ni۰.۶Mn۰.۴Fe۲O۴ OC is of high stability, high CH۴ conversion percentage means, and high H۲ production yield. The OCs samples are characterized by applying FT-IR, XRD, FESEM with X-ray spectroscopy EDX, BET, and TGA.

کلیدواژه ها:

Oxygen carrier ، NixMn۱-xFe۲O۴ nano-powder ، CL-SMR process ، Response surface method ، H۲ production