We report the preparation of calcium oxide (CaO)-based sorbents by ultrasonic spray pyrolysis (USP) with both experimental results and modeling of the sorption process. To mitigate CaO deactivation during carbonation/regeneration cycles, metal oxides with high melting temperatures were dispersed into CaO particles in this bottom-up synthetic method (USP), and their performance was experimentally characterized and evaluated over SO cycles. The performance of synthesized sorbents was then compared to those expected from an unreacted shrinking core model. The model was able to predict the experimental results and provide an explanation for the effect of sintering and agglomeration on the performance of the sorbents through a variable effective diffusivity. Moreover, it was used to extrapolate sorbent performance over large numbers of cycles.