Highly robust ZrO2-stabilized CaO nanoadsorbent prepared via a facile one-pot MWCNT-template method for CO2 capture under realistic calcium looping conditions

This research assessed the textural and structural characterizations and CO2 capture activity of novel and highly thermal-resistance ZrO2-stabilized adsorbents templated with MWCNT, prepared via a facile one-pot preparation approach. Various MWCNT contents, 2.5, 5, and 10 wt%, were incorporated into the CaO adsorbent containing 12.8 wt% ZrO2 species. The conducted structural properties revealed that the CaO grain size, surface area, and pore volume of untemplated ZrO2-supported CaO improved by 33.25%, 185%, and 141% through merging with 10 wt% MWCNT, conformed with FESEM images that showed the highly porous structure. Moreover, the TGA analyses under the severe calcium looping conditions, carbonation under 15 vol% CO2 balanced with N2 at 650 °C for 10 min, and calcination under 100 vol% CO2 at 930 °C for 10 min, demonstrated the incorporation of 10 wt% MWCNT into the ZrO2-stabilized CaO adsorbent increased cyclic durability and the ultimate CO2 capture capacity from 29.5% and 0.03 g CO2/g adsorbent to 61.12% and 0.1 g CO2/g adsorbent, indicating 107% and 233.3% enhancement, respectively. In addition to the significant reduction in CaO grain size and the formation of more high-volume pores, the influence of the MWCNT on calcium zirconate distribution into the CaO structure, mitigating CaO sintering and the agglomeration of CaO grains is another potential reason for the discussed multicyclic and textural improvements. The acquired findings indicated the effectiveness of MWCNT-template preparation method on textural, structural, and multicyclic properties of nano-scale ZrO2-promoted CaO adsorbents.