Enhanced Cyclic Stability of Composite-Modified Iron-Based Oxygen Carriers in Methane Chemical Looping Combustion: Mechanistic Insights from Chemical Calculations

Chemical Looping Combustion (CLC) technology has emerged as a promising approach for carbon capture owing to its CO2 separation capability, which addresses the pressing challenge of global climate change. Although iron-based oxygen carriers offer economic advantages owing to their abundance and low cost, their limited cyclic stability restricts their industrial deployment. This study focused on optimizing the performance of iron-based oxygen carriers through composite modification with Al2O3 and TiO2. Using Cantera (2.5.0) software and the minimum Gibbs free energy principle, conversion rates and product distributions of Fe2O3, Fe2O3/Al2O3, and Fe2O3/TiO2 were systematically analyzed under varying temperatures (800–950 °C), oxygen carrier-to-fuel molar ratios (O/C = 1–15), and pressures (0.1–1.0 MPa). The optimal conditions were identified as 900 °C, O/C = 8, and 0.1 MPa. After 50 simulation cycles, Fe2O3/Al2O3 and Fe2O3/TiO2 achieved average total reaction counts of 503 and 543, respectively, substantially exceeding 296 cycles for Fe2O3. The results indicated that Al2O3 and TiO2 improved cyclic stability via physical support and structural regulation mechanisms, thereby offering a practical carrier composite modification strategy. This study provides a theoretical basis for the development of high-performance oxygen carriers and supports the industrial application of CLC technology for efficient carbon capture and emission mitigation.