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 emssion 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 synghesized using the novel sol-gel combustion synthesis (SGCS) method and its reaction characteristics were further evaluated under the realistic coniditon, where the calcination temperatue was set as 950°C and the clacination atmosphere adopted was pure CO2. The experimental results over eighteen looping cycles for the synthetic CaO-ZrO2 sorbents indicated that the decay of CO2 capture and conversion under the realistic calicination condition was not avoided due to the severe sintering, and Ca8Zr2 should be preferred in the realistic CO 2 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 eighteen cycles by FSEM (field emission scanning electron microscopy) reavealed that the decaying of its CO2 capture capacity was mainly resulted from the closure of mesore pores present in the targeted sorbents. © Tsinghua University Press, Beijing and Springer-Verlag Berlin Heidelberg 2012.