Structurally improved, urea-templated, K2CO3-based sorbent pellets for CO2 capture

Abstract The development of K 2 CO 3 -based sorbents with desirable CO 2 capture capacity and mechanical property is highly necessary for its large-scale application. In this work, a range of extruded-spheronized K 2 CO 3 -based pellets containing different K 2 CO 3 loading (30–70 wt%) and Al 2 O 3 -based supports (i.e., activated alumina, Bayer aluminum hydroxide, kaolinite clay and calcium aluminate cement) were prepared for CO 2 capture. It is found that the distinct textural properties of different supports result in the obvious diversities in CO 2 uptake and mechanical property of K 2 CO 3 -based pellets. The activated alumina-supported sorbent pellets loaded with 50 wt% of K 2 CO 3 possess the highest CO 2 adsorption capacity of 2.29 mmol/g. It is mainly attributed to the moderate amounts of active component contributing to good textural properties and abundant CO 2 -philic sites, whereas excessive K 2 CO 3 loading will cause the destruction of porous structure, consequently the inferior CO 2 uptake. Moreover, the addition of 15 wt% of urea can furher enhace CO 2 uptake of the activated alumina-supported sorbent pellets loaded with 50 wt% of K 2 CO 3 , ∼3.10 mmol CO 2 /g. The improved CO 2 uptake is due to the significantly enhanced porosity of sorbent pellets as a result of urea decomposition. In addition, the urea-templated sorbent pellets still maintain the high compressive strength (18.96 MPa) and good attrition resistance (a weight loss of 0.59% after 4000 rotations).