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

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, CO2 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 CO2 capacity of the base adsorbent. In the presence of LUDOX, pellet hardness was lower, and led to the largest decrease in CO2 capacity. Formulation with 25% bentonite was found to provide pellets with post triamine functionalisation CO2 capacity equivalent to powder SBA-15, at an amine efficiency of 0.41 mol CO2/mol, while minimising pore blockage and maintaining a compressive strength of 1.5 MPa. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the formation of mesoporous silicas pellets using bentonite and colloidal silica, finding that bentonite was an effective single binder that formed mechanically strong pellets with up to 85% CO2 capacity retention. However, the presence of LUDOX led to lower pellet hardness and the largest decrease in CO2 capacity. Formulating with 25% bentonite provided pellets with post triamine functionalization CO2 capacity equivalent to powder SBA-15, while minimizing pore blockage and maintaining compressive strength.