Preparation of corncob-templated carbide slag sorbent pellets by agar method for CO2 capture: One-step synthesis and cyclic performance

•Agar method is used for one-step synthesis of carbide slag sorbent pellets.•Adding corncob powder as template in extra can provide rich porous structure.•The initial CO2 capture capacity for the sorbent is 0.534 gCO2/g.•After 15 cycles, the best CO2 capture capacity for the sorbent is 0.336 gCO2/g. Calcium-based sorbents are considered as one of the most promising sorbents for high-temperature CO2 capture. However, calcium-based sorbents are facing elution and sintering problems in fluidized bed reactors. In this work, corncob-templated carbide slag sorbent (C-CS) pellets were prepared by agar method. Then, the effects of template contents and calcination conditions on the CO2 capture performance of sorbent pellets were investigated. Adding corncob powder as template in extra during the synthesis sorbent pellets could further improve CO2 capture performance. With the template weight was extra 15 wt% to carbide slag (CS), the capture capacity had the most significant increase compared with the pure CS (about 17 %), and after 15 cycles, the highest capture capacity of 0.336 gCO2/g was observed. In terms of the effects of calcination conditions, after 15 cycles, the capture capacity of C-CS (with extra 15 wt% template) under moderate (850 ℃, 50 % CO2) and severe calcination (950 ℃, 100 % CO2) dropped from 0.455 gCO2/g to 0.242 gCO2/g, and from 0.320 gCO2/g to 0.180 gCO2/g, respectively. Further, in TGA, the highest capture rate of CCS-15cp reached 0.016 gCO2/g/s, with a CO2 capture capacity of 0.283 gCO2/g within the first minute. It indicated that the addition of corncob powder as template and the application of agar method could successfully improve the cyclic performance of C-CS sorbent pellets, as rich porous structure was generated during one-step synthesis.