(225l) Triamine-Grafted Mesoporous Silica Materials for Landfill Gas Purification

The challenge, however, is to develop adsorbent materials that combine high uptakes, fast adsorption kinetics, and favorable stability during cyclic adsorption-desorption. The potential of amine-grafted silica (i.e., aminosilicas) was investigated for single-stage landfill gas purification via simultaneous removal of CO₂, H₂S, and water vapor. Custom aminosilicas were synthesized by covalent grafting of triamines onto mesoporous silica in the presence of different water and amine amounts. Screening adsorption experiments were completed at 40 °C in the presence of dry 30 vol.% CO₂ in N₂, and performance was measured using thermogravimetric analysis. Selected materials with equilibrium CO₂ uptakes greater than 1.5 mmol/g were chosen for further assessments in terms of CO₂ adsorption kinetics. The highest-performing aminosilica achieved fast CO₂ adsorption by reaching 80% of its equilibrium uptake in one minute. This material was subjected to rigorous 100-cycle testing and maintained 100% of its initial CO₂ uptake throughout cycling. The final candidate also underwent column-breakthrough tests in the presence of different dry and humid gas streams containing CO₂, H₂S, and water vapor, and achieved concurrent and complete (100%) removal of all target impurities. The results suggest promising potential of aminosilicas as a viable adsorbent material for biogas purification.