Flow properties of CO2 sorbent powders modified with nanosilica

•Bulk flow properties of limestone and limestone/nano-silica dry mixtures are studied.•Particle size distribution analyses are performed to assess their mechanical stability.•Experiments are carried out on raw and subjected to calcination/carbonation materials.•Modification of natural limestone with nano-silica improves its fluidizability.•Mechanical and thermal stability of the modified CO2 sorbents is enhanced.

In this work, the flow behavior of a CO2 sorbent precursor (natural limestone) and a modified sorbent precursor, obtained by dry mixing the natural limestone and a silica nanostructured powder, is investigated. After dry mixing, small silica nanoparticle aggregates are seen to coat the limestone particle surface, which serves to decrease interparticle adhesion thus improving powder flowability. The tensile strength of the modified material subjected to small consolidation stresses has been tested before and after calcination. In addition, laser diffraction particle size analysis has been performed to test the mechanical strength of the aggregates as they are pre-dispersed in-situ by high energy processes such as high velocity air jets or ultrasonication in a liquid. The results also indicate that calcination leads to an increase of the average size of the limestone/nanosilica composite aggregates whose mechanical strength is enhanced as compared to that of calcined limestone aggregates.

Graphical abstractModification of natural limestone with nanosilica enhances its mechanical/thermal stability and improves its fluidizability.Figure optionsDownload full-size imageDownload as PowerPoint slide