Theoretical approaches in hot CO2 capture using modified CaO-based sorbents: Review

CO2 capture at high temperature using CaO-based sorbent is increasingly being implemented at pilot scales for post- and pre-combustion technologies worldwide. The key issue in these technologies is the sorbent degradation under repeated cycles due to sintering-induced agglomeration that adversely impacts the solid inventory and plant operation. Sorbent modifications to inhibit sintering primarily include applying suitable synthetic techniques to enhance morphological properties and infusing stabilizers to disperse CaO. Given the wide range of material options (inert/stabilisers), the theoretical prediction of plant-level performance becomes indispensable for design upscale. Plant modelling subsumes sorbent-level kinetics, occurring at the microscopic scale, into the column-level transport occurring at macroscopic scales. This review emphasizes different theoretical approaches in CaO-based high-temperature CO2 capture. These encompass (I) thermodynamics addressing the equilibrium characteristics, modes of operation and integrated calcium looping technologies; (II) sorbent-level kinetic models describing sorbent morphology evolution and underlying physico-chemical phenomena; (III) column-level hydrodynamic models coupling chemical kinetics to reactor hydrodynamics for predicting the breakthrough characteristics and capture efficiencies. Overall, the review provides a comprehensive theoretical perspective for plant-level operation.

Automated summary

This review discusses theoretical approaches in high-temperature CO2 capture using CaO-based sorbent, including thermodynamics, sorbent-level kinetic models, and column-level hydrodynamic models. The theoretical prediction of plant-level performance is crucial for design upscale.