Refractory dopant-incorporated CaO from waste eggshell as sustainable sorbent for CO2 capture: Experimental and kinetic studies

Abstract

This work investigates the development of dopant-stabilized CaO-based sorbents for CO2 capture and studies the kinetics of the carbonation reaction. Eggshell as biogenesis calcium waste was calcined to obtain low cost CaO powder. Several refractory dopants (Ti, Al, Cu and Zi) were then incorporated within the CaO matrix to prepare robust sorbents. The CO2 capture performance of the developed sorbents was assessed in some calcination–carbonation cycles performed in Thermogravimetric analyzer (TGA). Among the developed sorbents, Zr-doped CaO exhibited superior performance and durability, where a conversion of around 88% could be sustained within 20 cycles. To have an insight into the rate controlling mechanism and fundamental concept of activation energy, kinetic study was performed on the carbonation reaction of the Zr-doped CaO sorbent. Kinetic results based on the shrinking core model suggested that the carbonation mechanism was controlled by a combination of resistances arising from diffusion of CO2 through the carbonate layer and its chemical reaction at the CaO–CaCO3 interface. The intrinsic and diffusional activation energies were obtained as 39.4 and 46.5kJ/mol, respectively.