Attrition Study of Cement-Supported Biomass-Activated Calcium Sorbents for CO₂ Capture

An enhanced CO₂ capacity was reported recently for biomass-modified Ca-based sorbent, but undesired attrition resistance was also observed. In this study, cement was used as a support for biomass-activated calcium sorbent during the granulation process to improve the poor mechanical resistance. Attrition tests were carried out in an apparatus focused on impact breakage to evaluate how the biomass addition and cement support influence the particle strength during Ca looping. The results showed that biomass addition impairs the mechanical strength and that a cement support can improve it, as reflected in the breakage probability and size change after impact of pellets that had experienced calcination and multiple calcination/carbonation cycles. Larger-sized particles suffered more intense attrition. The mechanical strength of the sorbents declined significantly after higher-temperature calcination but increased after carbonation. After multiple cycles, the mechanical strength of particles was greatly enhanced, but more cracks emerged. A semiempirical formula for calculating the average diameter after attrition based on Rittinger's surface theory was developed. Observations of the morphology of the particles indicated that particles with more porosity and more cracks were more prone to breakage.