Honeycomb Zeolite-Enabled Monolithic K ₂ CO ₃ with Exceptional Cyclic Uptake and SO ₂ Tolerance for Flue Gas CO ₂ Capture

Potassium carbonate represents a highly attractive candidate for low-temperature CO 2 adsorption due to its favorable reaction window, and monolithic structuring stands as a key strategy to advance industrial translation. However, the practical deployment is severely limited by unsatisfactory CO 2 uptake and poor tolerance to SO 2 in flue gas. Herein, we systematically explore CO 2 adsorption–desorption behaviors, reaction kinetics, and sulfur-resistance enhancement of novel monolithic K 2 CO 3 adsorbents to overcome these bottlenecks. The optimized monolithic SZ-K50, constructed by loading 50 wt % K 2 CO 3 onto a honeycomb zeolite support, demonstrates a remarkably stable CO 2 capacity of 3.33 mmol/g and 92% K 2 CO 3 conversion over 20 consecutive cycles. Kinetic analysis via the Avrami fractional model clarifies the reaction mechanism, yielding adsorption and desorption apparent activation energies of 13.23 and 35.15 kJ/mol, respectively. Notably, a facile SO 2 -poisoning mitigation strategy is proposed by introducing an upstream monolithic MnO 2 sacrificial layer, which enables durable and efficient CO 2 capture from impurity-containing flue gas. Economic evaluation confirms that the monolithic adsorbent cuts the preparation costs by approximately 50%, achieving an exceptional balance among CO 2 capacity, cyclic stability, and economic viability.