Fe-based oxygen carrier for the chemical looping combustion of CO, H2, and CH4 syngas in fluidized bed reactor under interruption of H2S

Abstract

Chemical looping combustion (CLC) reduces the CO2 capturing cost, elevates combustion efficiency, and prevents NOx formation. This study applied Fe2O3/SiO2 and Fe2O3/Al2O3 oxygen carriers to react with H2, CO and CH4 under different operating setup and examined the interference of H2S. Examination was also conducted on the reaction kinetics, cycle test, and characterization of oxygen carriers. Reduction of oxygen carrier from Fe2O3 to between FeO and Fe occurred during the reaction. The higher syngas concentration led to higher diffusion capacity and promoted utilization of oxygen carriers. Carbon deposition was enhanced by excess concentration of CO and CH4. Involvement of H2S led to declining of performance due to the presence of carbonyl sulfide (COS) and FeS. With Fe2O3/SiO2, application of multiple redox cycles reduced the utilization value to 43 % due to formation of Fe2SiO4. Analysis of exhausted gas after reaction was applied in study of proposed reaction mechanism. Study of reaction kinetics using Type I deactivation test indicated a well fitted result with experimental data with R2 in the range of 0.9605–0.9976. Thus, compared to other studies with discussion only on CO, H2, or CH4 in CLC, this study offered a comprehensive research on interruption of H2S, characterization, and reaction kinetics.