INVESTIGATING THE POTENTIAL OF AMINE-GRAFTED SILICA MATERIALS FOR SIMULTANEOUS REMOVAL OF CARBON DIOXIDE, WATER VAPOR, AND HYDROGEN SULFIDE FROM LANDFILL GAS

Amine-grafted silica (i.e., aminosilicas) was investigated for single-stage landfill gas purification via simultaneous removal of CO2, H2S, and water vapor. Aminosilica materials were synthesized by covalent triamine grafting onto mesoporous silica with custom amounts of water and amine. Screening adsorption experiments were completed in dry 30 vol.% CO2 in N2 at 40 °C and assessed using thermogravimetric analysis. Materials with equilibrium CO2 uptakes greater than 1.5 mmol/g were chosen for CO2 adsorption kinetics assessments. The highest-performing aminosilica achieved fast CO2 adsorption by reaching 80% of its equilibrium uptake in one minute. This material also maintained 100% of its initial CO2 uptake when subjected to rigorous 100-cycle testing. It 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 that aminosilicas can purify landfill gas in a single stage.