Session: ENFL General Posters:

CaO-based CO₂ sorbents play a significant role in sorption enhanced methane steam reforming process for hydrogen production and CO₂ emission. However, the CO₂ sorption capacity and cyclic stability of the CaO-based sorbents still remain to be improved for the loss of CO₂ sorption capacity during the repeated carbonation-calcination cycles, which was derived from the sintering of CaO grains. In order to prevent the sorbent grains from sintering during the carbonation-calcination cycles so as to provide higher surface area and proper pore structure, promising strategies have been proposed to improve the cyclic sorption performance of CaO sorbents, involving thermal pretreatment, incorporation of supports or dopants, modification of precursors, and hydration treatment. Considering both the sorption performance and the cost for industrial production, the most promising technology is to modify CaO by inert materials. In this work, a series of CaO-based CO₂ sorbents doped with Al and Zr were prepared via modified sol-gel method. The effects of the dopants type on the structure, morphology and CO₂ sorption performance were investigated to obtain superior CO₂ sorption capacity and stability. Results showed that the sorbents doped with Zr or Al both exhibited optimal cyclic stabilities. The sorbents doped with Zr remained 98% CO₂ sorption capacity after 25 cycles, which was due to the formation of CaZrO₃. CaZrO₃ had high Taman temperature and small volume expansion rate during repeated carbonation-calcination cycles, which provided a certain pore for the diffusion of CO₂ into the particles of sorbents. The sorption capacity of the sorbents doped with Al was 5.43 mmol CO₂/g sorbents, which was higher than that of our previous results. This might be due to the different preparation temperature, which resulted in the formation of amorphous Al₂O₃, not Ca₃Al₂O₆, and finally hindered the sintering of CaO grains and strengthened the mass transfer of CO₂.

Jie Feng

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