Utilizing silica fume and synthetically produced mesoporous silicas for simulated flue gas CO₂ adsorption

ABSTRACT

Carbon capture and storage (CCS) is crucial in mitigating greenhouse gas emissions. Solid adsorbents, notable for their reusability and corrosion resistance, are gaining attention in CO₂ gas separation. This study uses Silica fume as an adsorbent and silica source for SiO₂ and MCM-41 silica-based adsorbents. Silica was extracted via an alkaline dissolution method, and adsorbents were synthesized using a CO₂-induced precipitation method, chosen for its shorter synthesis time and CO₂ utilization. The effects of pore volume, average pore diameter, and specific surface area on amine loading and CO₂ adsorption capacity were investigated using CTAB surfactant in SiO₂ synthesis, resulting in MCM-41. The synthesized adsorbents were modified with TEPA and DEA amines due to their high affinity for CO₂. After determining optimal amine loading, the impact of combining TEPA with DEA was examined. The highest CO₂ adsorption capacity under simulated flue gas conditions (15% volume CO₂ and 85% volume N₂) was 198 milligrams per gram of adsorbent for the SiO₂ adsorbent functionalized with 50% by weight amine (28% TEPA and 22% DEA). Variations in CO₂ adsorption over time, the influence of adsorbent quantity on adsorption capacity, the affinity of the adsorbent for N₂ adsorption, and the adsorption–desorption cycle were investigated. The 28%TEPA-22%DEA-SiO₂ adsorbent emerged as the optimal choice due to its large total volume and average pore diameter, absence of a template in its structure, excellent performance in CO₂ adsorption, lack of affinity for N₂, and robust adsorption–desorption stability.

GRAPHICAL ABSTRACT

KEYWORDS:

• Silica fume
• CO₂ adsorption
• SiO₂ synthesis
• MCM-41 synthesis
• amine

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Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article. Raw data that supports the findings of this study will be available upon a reasonable request.

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Funding

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