Silica Selection and Properties
Selecting silica for pilot plant
Numerous researchers have attempted to increase surface area and pore and volume of silicas, enhancing pore interconnectivity, to increase PEI loading and thus CO2 uptake than can be achieved with both relatively low-cost commercially available mesoporous silicas and those with defined pore geometries. Macroporous cellular foams have achieved the highest mesopore volumes (ca. 2.5 ml/g) and PEI loadings up to 70 wt.% (e.g. Sun et al. 2018) with CO2 adsorption capacities of 15-20% wt.%. However, challenges exist in preparing these materials with the right particle size range for fluidised beds.
PQ Corporation manufactures mesoporous silicas from sodium silicate with pore volumes up to 2 ml/g and these will be the focus of the investigation into silica properties, due to their potential affordability compared to silicas with larger pore volumes prepared from organic precursors outlined above.
By screening the silicas at lab-scale we will determine whether high PEI loadings (50%) can be achieved by increasing the pore volume slightly while maintaining the control on particle size. Considering cost of the silica as well as performance, the silica for the pilot-scale tests will then be selected.