Pelletization and attrition of CaO-based adsorbent for CO2 capture

CaO-based adsorbent pellets from limestone and carbide slag powder were prepared by an extrusion-spheronization method. Three types of binder and peptizer materials were introduced to improve the adsorption performance and mechanical properties of adsorbent pellets. Weibull statistics was employed to analyze the compressive stress of adsorbent pellets. The results revealed that pseudo-boehmite and nitric acid were the favorable choice of binder and peptizer for preparing CaO-based adsorbent pellets with enhanced chemical and mechanical properties. The addition of pseudo-boehmite (PB) improved the pore distribution characteristics by increasing the pores within 10-100 nm, and the addition of nitric acid brought favorable mechanical reliability by providing a large amount of H+, thereby interacting with multiple PB particles to form a network structure. It was shown that when 3 wt.% pseudo-boehmite and 15 wt.% nitric acid were used, the favorable performance of the molding pellets could be obtained (carbonation conversion: 36%, compressive stress: 25.3 MPa; attrition rate: 0.46 wt.%/hr), which had promising prospects for practical CO2 removal.