Quantitative Analysis of Catalytic Oxidation Reactions in Oxygen Carrier Aided Fluidized Bed Combustion

Oxygen carrier aided combustion (OCAC) enhances fluidized bed combustion efficiency by replacing inert bed material with active oxygen carrier (OC), but the catalytic role of OC in the OCAC process has yet to receive sufficient attention. Combining experimental studies and computational analysis, this work quantitatively analyzes the direct oxidation reaction (DOR) and catalytic oxidation reaction (COR) involving OC in a lab-scale bubbling fluidized bed reactor. Three active materials─ilmenite ore, a synthetic catalyst, and a Cu-based OC─were tested under different reaction atmospheres and temperature conditions. Under the conditions of three active bed materials, the conversion ratio of fuel combustion increased. Apparent kinetic studies demonstrate that these active materials lower the activation energy effectively catalyzing the oxidation reaction. The results of reaction decoupling indicate that the COR plays a significant role and cannot be ignored in the OCAC. At 550 °C, COR accounted for 44%, 95%, and 96% of CO combustion with ilmenite ore, synthetic catalyst, and Cu-based OC, respectively; it accounted for 95% with two synthetic materials for CH4 at 700 °C. Furthermore, density functional theory (DFT) calculations reveal the competitive relationship between DOR and COR. These findings are crucial for the practical applications of OCAC technology.