Fe2O3/TiO2 oxygen carrier for chemical looping combustion of CO, H2, and CH4 in a fluidized bed reactor

Abstract

The high amount of CO2 has been released to the atmosphere and causes severe environmental issues related to global warming and climate change. Carbon capture and storage (CCS) technology, including chemical looping combustion (CLC), is considered as the promising strategy to reduce the cost of CO2 separation, avoid the NOx increment, and increase the combustion efficiency. In this study, the 40 wt%Fe2O3/TiO2 was prepared using the incipient wetness impregnation method for the application as an oxygen carrier. The oxygen carrier was reacted with coal and biomass gasified syngas composed of H2, CO, and CH4 in a fluidized bed reactor under various operating conditions. A higher reaction rate was achieved by the increment of superficial velocity, operating temperature, and the concentration of CO or H2. With 25% CO, application of 1000 °C operating temperature resulted in a higher utilization value compared to 800 °C operating temperature. When CH4 was applied in the system, the occurrence of hydrogen production and carbon deposition due to the decomposition interrupted the analysis and calculation process. The higher syngas concentration in the CLC test led to a greater reaction rate due to the better diffusion capability. However, the higher reaction rate caused blocking and sintering on the oxygen carrier and reduced the final utilization at the end of reaction. The test under 10 redox cycles, kinetics analysis, and proposed reaction mechanism were also carried out by this study.