A green and multi-win strategy for coal fly ash disposal by CO2 fixation and mesoporous silica synthesis

Coal combustion provides plenty of energy, along with enormous coal fly ash (CFA) and CO2 emission. CFA could be recycled for mesoporous silica synthesis, but expensive templates are usually needed. In this work, we proposed a multi-win strategy using CO2 as the precipitator and template. Mesoporous silica powders, with a maximum specific surface area of 355.45 m2/g, a pore volume of 0.73 cm3/g, and an average pore size of around 7.67 nm, were synthe-sized. The influences of silicon concentration, CO2 flow rate, and ultrasound were investigated. In addition, the Na2CO3 by-product was produced with a purity of over 92 %. By averagely calculating, 1 ton CFA could generate 285 kg mesoporous silica and 1.02 t crude Na2CO3. Around 433 kg of CO2 could be absorbed. Therefore, multi -goals of CFA disposal, CO2 storage, and valuable silica materials production were realized, and the study could pave the way for large-scale industrial applications.

Automated summary

Coal combustion produces abundant energy, as well as significant amounts of coal fly ash (CFA) and CO2 emissions. This study proposes a multi-win strategy using CO2 as both a precipitator and template for the synthesis of mesoporous silica. The synthesized silica powders had a high specific surface area and pore volume. The study successfully achieved the goals of CFA disposal, CO2 storage, and valuable silica material production, paving the way for large-scale industrial applications.