Improving CO2 sorption performance of CaO/Ca3Al2O6 sorbents by thermally pretreated in CO2 atmosphere

CaO-based CO2 sorbents play a significant role in sorption enhanced methane steam reforming process for hydrogen production and CO2 emission reduction. In this work, pretreatment of CaO/Ca3Al2O6 sorbents in CO2 atmosphere at different temperatures was investigated for its influence on CO2 sorption capacity and cyclic stability. The sorbents were synthesized to contain a CaO to Al2O3 mass ratios of 9:1, and then subjected to cycling tests with repeated carbonation and calcination process. Results showed that the sorbents pretreated by CO2 at 650 degrees C obtained a minimum CaO grain size of 40.7 nm and a maximum surface area of 13.1 m(2). g(-1). This resulted in an increase in CO2 sorption capacity, up to 7.60 mmol CO2. g(-1) sorbent. After 50 cycles, the CO2 sorption capacity decreased, but still remained 10% above those for the original (no pretreatment) sample. The mechanism about the improved CO2 sorption performance of the pretreated sorbents was also postulated. (C) 2017 The Authors. Published by Elsevier Ltd.