Comparative Evaluation of Different MOF and Non-MOF Porous Materials for SO2 Adsorption and Separation Showing the Importance of Small Pore Diameters for Low-Pressure Uptake

Abstract

The search for adsorbents for flue gas desulfurization processes is a current interest. For the first time, a comparative experimental study of SO2 adsorption by porous materials including the prototypical metal–organic frameworks NH2-MIL-101(Cr), Basolite F300 (Fe-1,3,5-BTC), HKUST-1 (Cu-BTC), the zeolitic imidazolate frameworks (ZIF)-8, ZIF-67, the alumosilicate Zeolite Y, the silicoaluminumphosphate (SAPO)-34, Silica gel 60, the covalent triazine framework (CTF)-1, and the active carbon Ketjenblack is carried out. Microporous materials with pore sizes in the range of 4–8 Å or with nitrogen heterocycles are found to be optimal for SO2 uptake in the low-pressure range. The SO2 uptake capacity at 1 bar correlates with the Brunauer-Emmett-Teller-surface area and pore volume rather independently of the surface microstructure. Zeolite Y and SAPO-34 are stable toward humid SO2. The materials Zeolite Y and CTF-1(600) show the most promising SO2/CO2 selectivity results with an ideal adsorbed solution theory selectivity in the range of 265–149 and 63–43 with a mole fraction of 0.01–0.5 SO2, respectively, at 293 K and 1 bar.