Zr‐Induced Kinetic Stabilization and Enhanced Cyclic CO ₂ Capture Performance of CaO‐Based Sorbents

Calcium oxide is a promising high‐temperature CO ₂ sorbent for calcium looping, yet its practical application is limited by rapid capacity decay due to sintering and pore collapse during cyclic carbonation/calcination. Although metal doping has been widely employed to improve structural stability, the quantitative relationship between dopant‐induced phase evolution, reaction kinetics, and long‐term durability remains unclear. Here, seven metal dopants (Zr, Mn, Ce, Ni, Fe, Cr, and Co) were incorporated into CaO to systematically evaluate their influence on multiscale reaction behavior. Among them, Zr‐modified CaO exhibits superior cyclic stability, retaining more than twice the CO ₂ uptake of pristine CaO after 40 cycles. Structural analyses (XRD, BET, SEM) reveal that Zr promotes the formation of a thermally stable CaZrO ₃ phase that acts as a refractory skeletal/spacer phase to mitigate morphological densification and preserve pore connectivity. Isoconversional and pressure‐corrected kinetic analyses show that Zr stabilizes the apparent activation energy across the full conversion range and maintains a consistent phase‐boundary‐controlled mechanism, thereby delaying diffusion limitations during cycling. In contrast, other dopants either reduce initial activation energy without preventing long‐term degradation or introduce unfavorable kinetic effects. These results establish a quantitative structure–energy–stability correlation for designing durable CaO‐based CO ₂ sorbents.