Hydrotalcite/SBA15 composites for pre-combustion CO2 capture: CO2 adsorption characteristics

Hydrotalcite-like compounds (HT) show potential as CO2 adsorbent materials for pre-combustion CO2 capture applications, but require improvements in stability, adsorption capacity and kinetics. In this study, HT/SBA15 hybrids (with different Mg/Al ratios varying from 0.3 to 3) have been synthesised using a two-stage grafting method to coat a mesoporous SBA15 with hydrotalcite layers. The HT/SBA15 hybrids showed significant improvement in intrinsic CO2 uptake (per mass of HT), initial uptake rate, and multicycle stability compared to unsupported HT. Compared to previously reported nanostructured carbon supports (e.g. CNF, MWCNTs), the HT/SBA15 hybrids were found to be more thermally stable and exhibit comparable adsorption uptake and rates. In particular, the use of SBA15 as a support is shown to prevent the gradual loss in weight from thermal decomposition observed for HT/MWCNT or HT/GO composites over extended cycling.