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

Abstract CaO-based CO 2 sorbents play a significant role in sorption enhanced methane steam reforming process for hydrogen production and CO 2 emission reduction. In this work, pretreatment of CaO/Ca 3 Al 2 O 6 sorbents in CO 2 atmosphere at different temperatures was investigated for its influence on CO 2 sorption capacity and cyclic stability. The sorbents were synthesized to contain a CaO to Al 2 O 3 mass ratios of 9:1, and then subjected to cycling tests with repeated carbonation and calcination process. Results showed that the sorbents pretreated by CO 2 at 650 oC 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 CO 2 sorption capacity, up to 7.60 mmol CO 2 ·g -1 sorbent. After 50 cycles, the CO 2 sorption capacity decreased, but still remained 10% above those for the original (no pretreatment) sample. The mechanism about the improved CO 2 sorption performance of the pretreated sorbents was also postulated.