Preparation and Application of the SGCS-Made CaO/ZrO₂ Sorbent for Cyclic CO₂ Capture

Abstract

Calcium looping method was considered as one of the efficient and cost-effective options to mitigate CO₂ emission from coal combustion and gasification processes. The decay of CO₂ capture capacity for the CaO-based sorbent over multiple carbonation/calcination cycles is of a great concern and hinder its application in the realistic CO₂ capture process. A CaO-ZrO₂ sorbent was synthesized using the novel sol-gel combustion synthesis (SGCS) method and its reaction characteristics were further evaluated under the realistic condition, where the calcination temperature was set as 950°C and the clacination atmosphere adopted was pure CO₂. The experimental results over 18 looping cycles for the synthetic CaO-ZrO₂ sorbents indicated that the decay of CO₂ capture and conversion under the realistic calcination condition was not avoided due to the severe sintering, and Ca8Zr2 should be preferred in the realistic CO₂ capture process with regard to its reaction characteristics (including its CO₂ capture capacity, conversion and deactivation constant) and economical factor. Finally, observation of the Ca8Zr2 sorbent over 18 cycles by FSEM (field emission scanning electron microscopy) revealed that the decaying of its CO₂ capture capacity was mainly resulted from the closure of mesopores present in the targeted sorbents.