Preparation And Reactivity Investigation Of Iron-based Oxygen Carriers For Hydrogen Production Via Biomass Derived Syngas Chemical Looping Process

With Chemical looping combustion technology is a new type of combustion,which has high energy efficiency, inherent CO2separation characteristics and lowNOXgeneration. For the purpose of transferring the low value biomass waste to highvalue green energy, the chemical looping combustion of pyrolysis gas from biomasswaste to production hydrogen can achieve the utilization of biomass waste, and thelow energy consumption of separation and capture process of CO2. Fe-based oxygencarrier is the key factor in the process of chemical looping to produce hydrogen frombiomass waste. In this paper, mechanical mixing grinding ball method andimpregnation grinding ball method were applied to prepare Fe-based oxygen carriersamples, and accuracy and yielding testing of these two methods were done. Specificsurface area and porosity analyzer and X-ray diffractometer were applied to characterthe physical and chemical structure of Fe-based oxygen carriers, and the reductionreaction performance and hydrogen production performance were tested on TGA andfixed-bed reactor.Results showed that the yielding of Fe-based oxygen carriers synthesized byboth mechanical mixing grinding ball method and impregnation grinding ball methodcan reach95%, and actual components of Fe-based oxygen carriers were consistentwith the theoretical design, indicating that these two methods can be applied tolarge-scale sample preparing. The BET surface area of samples was1~3m2/g, whichwas close to the samples prepared by sol-gel method previously. The oxygen transferactivity of Fe2O3in Fe-based oxygen carriers was consistent with the theoretical value.After calcination under1100oC, the BET surface area and reactivity of Fe-basedoxygen carriers decreased, and950oC was chose to be the appropriate calcinationtemperature.Both the reaction conversion and reaction rate of Fe-based oxygen carriersincreased with the reaction temperature when reacting with H2and CO. The reductionrate of H2is higher than that of CO. As the reaction proceeding, the reaction rate ofH2increased, while the reaction of CO decreased. The nucleation and nuclei growth model and unreacted shrinking core model were applied to study the reaction kineticsof Fe-based oxygen carriers reacting with H2and CO, respectively.The fixed-bed reactor was used to test the reaction performance of Fe-basedoxygen carriers. The solid conversion of samples prepared by both methods rangedfrom22%~30%and maintained stable in10cycles. Results of10-cycles hydrogenproduction tests showed that the hydrogen production efficiency of Fe-based oxygencarriers prepared by mechanical mixing grinding ball method ranged from0.45~0.75,and the hydrogen production efficiency of Fe-based oxygen carriers prepared byimpregnation grinding ball method ranged from0.35~0.65. The average hydrogenproduction efficiency of Fe-based oxygen carriers prepared by impregnation grindingball method was lower than samples prepared by the other method.