Formulation, adsorption performance, and mechanical integrity of triamine grafted binder-based mesoporous silica pellets for CO2 capture

Abstract

This work explored the formation of mesoporous silicas pellets using a range of bentonite and colloidal silica (LUDOX) fractions, aiming to optimise the binder composition that minimises any deteriorating effects on adsorption performance, while providing adequate mechanical integrity. Thermogravimetric analysis, scanning electron microscopy, and dynamic mechanical analysis were used to structurally characterise the pellets. Further, CO 2 adsorption isotherms of synthesised pellets, pre and post triamine grafting, were measured. Bentonite was found to be an effective single binder that forms mechanically strong pellets and retains up to 85% of CO 2 capacity of the base adsorbent. In the presence of LUDOX, pellet hardness was lower, and led to the largest decrease in CO 2 capacity. Formulation with 25% bentonite was found to provide pellets with post triamine functionalisation CO 2 capacity equivalent to powder SBA-15, at an amine efficiency of 0.41 mol CO 2/mol, while minimising pore blockage and maintaining a compressive strength of 1.5 MPa.