Advanced High-Temperature CO Sorbents with Improved Long-Term Cycling Stability.

Developing novel sorbents with maximum carbonation efficiency and good cycling stability for CO capture is a promising route to sequester anthropogenic CO. In this work, we have employed a green synthesis method to synthesize CaO-based sorbents suitably stabilized by MgO and supported by generated carbon under inert atmosphere. The varied amounts (10-30 wt %) of MgO were used to stabilize the CaO. The supported mixed metal oxide (MMO) sorbents were screened for high-temperature CO capture under CO rich (86% CO) and lean (14% CO) gas streams at 650 °C and atmospheric pressure. The MMO sorbents captured 53-63 wt % of CO per gram of sorbent under 86 and 14% CO, accounting for about 98% carbonation efficiency, which outperforms the CO capture capacity of limestone derived CaO (L-CaO) sorbents (22.8 wt %). All of the synthetic MMO sorbents showed greater capture capacity and cyclic stability when compared to benchmark L-CaO. Because of the high carbonation efficiency and cycling stability of g-CaMgO sorbent, it was tested for 100 carbonation/regeneration cycles of 5 min each under CO lean conditions. The g-CaMgO sorbent showed exceptional CO capture capacity and cycling stability and retained about 65% of its initial capture capacity after 100 cycles.