High-temperature CO2 sorption by Ca-doped Li4SiO4 sorbents

摘要

Ca-doped Li4SiO4 (LiCa) sorbent was synthesized using a solid-state reaction method. The CO2 sorption capacity of the sorbents was thermogravimetrically analyzed in the presence of a pure CO2 flux. The cyclic performances of the sorbents were investigated in a twin fixed-bed reactor with absorption and desorption temperatures of 700 degrees C and 800 degrees C, respectively. The results indicate that the surface area of Li4SiO4 increased from 0.064 m(2) g(-1) to 0.314 m(2) g(-1) as the Ca doping content increased to 32 mol%, which enabled the sufficient contact between CO2 and Li4SiO4, and enhanced its CO2 sorption. The transformation of the Ca species from Ca2SiO4 to Li2CaSiO4 during the absorption process was helpful for the transfer of CO2 to Li4SiO4, and the transformation of Li2CaSiO4 to Ca(2)Sia(4) in the desorption process favors CO2 desorption. Due to the special composition and structure, Li4SiO4 doped with 6 mol% of Ca had a maximum CO2 sorption of 35.1 wt% at 700 degrees C for 1 h and exhibited an excellent cyclic performance for CO2 sorption/desorption. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.