Comparative study on low-temperature CO2 adsorption performance of metal oxide-supported, graphite-casted K2CO3 pellets

K 2 CO 3 -based adsorbent pellets produced by graphite-casting method are promising alkali metal-based solid CO 2 adsorbents. The incorporation of porous metal oxide supports is an effective to enhance CO 2 adsorption capacity of K 2 CO 3 -based adsorbent pellets. In this work, graphite-casted K 2 CO 3 -based adsorbent pellets incorporated with different porous supports (i.e., TiO 2 , ZrO 2 , and SiO 2 ) were prepared for CO 2 capture. Comparatively, the ZrO 2 -supported, K 2 CO 3 pellets loaded with 30 wt% of K 2 CO 3 exhibit the highest CO 2 adsorption capacity, approximately 0.93 mmol/g. For the SiO 2 -supported K 2 CO 3 adsorbent pellets, the high calcination temperature (>700 °C) required to remove the graphite layer covering the pellet surface will cause the formation of new eutectics (i.e., K 2 Si 2 O 5 and K 2 Si 4 O 9 ), which leads to the collapse of the adsorbent pellets. Low calcination temperature of 500 °C can avoid the collapse of the SiO 2 -supported K 2 CO 3 adsorbent pellets and remove most of the graphite on the surface. Moreover, the CO 2 adsorption capacity can be further increased to 1.30 mmol/g by adding 20 wt% of microcrystalline cellulose to the SiO 2 -supported K 2 CO 3 adsorbent pellet. Although the adsorption capacity of structurally improved, SiO 2 -supported K 2 CO 3 pellets is still inferior to that of structurally improved, ZrO 2 -supported K 2 CO 3 pellets, they exhibit great cost advantage. Therefore, SiO 2 -supported K 2 CO 3 pellets with 20 wt% of microcrystalline cellulose have industrial application prospects.