CHARACTERIZATION OF POROUS ALUMINUM SILICATES FOR CO₂ ADSORPTION

Abstract

Enhancement of CO₂ removal using adsorbent agents is a promising technique to reduce the atmospheric CO₂ levels. The objectives of this study were to develop novel porous aluminum silicates with different Si/Al molar ratios and to investigate their properties for CO₂ adsorption and recovery with the pressure swing adsorption (PSA) process. At a pressure less than 5 kPa, the amount of CO₂ adsorption by the porous aluminum silicates at each pressure increased with decreasing the Si/Al molar ratios from 2.0 to 1.1. Adsorption of CO₂ by the porous aluminum silicates is closely related to the number of ultra-micropores at a pressure less than 5 kPa and the specific surface area at a pressure greater than 8 kPa. At a CO₂ partial pressure less than 18 kPa, Zeolite-13X has a greater CO₂ recovery than any other porous aluminum silicates. Contrarily, the porous aluminum silicates have a greater CO₂ recovery than Zeolite-13X at a CO₂ partial pressure greater than 18 kPa. The efficient CO₂ recovery by porous aluminum silicates at a pressure greater than 8 kPa requires a large number of pores with 1.3 to 2.9 nm in diameter and a large specific surface area.