<p>Chemical looping combustion (CLC) is an emerging technology with significant potential for achieving highly efficient capture of pure CO₂ during fuel combustion. Biomass, as a fuel source, offers the added advantage of carbon negativity. In this study, a coupled process combining biomass pyrolysis pretreatment and chemical looping combustion (PYR-BCLC) was simulated. Four types of iron-based oxygen carriers (OCs)—Fe₂O₃ (Fe2), Ca₂Fe₂O₅ (Ca2), CaFe₂O₄ (Ca), and CoFe₂O₄ (Co)—were employed in the reactions. This study examined the effects of the OC-to-biomass ratio (O/B) and combustion temperature on the system’s products and overall performance. Furthermore, a CO₂ loop was implemented to evaluate the influence of CO₂ cycling on the system. The results indicated that as the O/B ratio increased, the carbon capture efficiency (CCE) for all four OCs reached 99.95%. Fe2 generated purer CO₂, whereas Ca2, Ca, and Co demonstrated greater selectivity in their performance. Elevated temperatures accelerated the overall reaction rate, favoring the production of H₂ and CO while suppressing the formation of CO₂ and CH₄. CO₂ cycling moderately inhibited CO₂ generation, making the process more suitable for chemical looping gasification. Upon complete reaction, Fe2 and Co exhibited significantly higher consumption rates compared to Ca2 and Ca, although they produced purer CO₂. The study concluded that OCs with more reaction stages tend to experience higher consumption during complete reactions, and increasing the reaction temperature further enhances OC consumption.</p>