Metal-organic framework-derived NaMO adsorbents for low-temperature SO removal.

This work reported the fabrication of NaMO-type adsorbents from air calcination of (Na, M)-trimesate metal-organic frameworks. NaMnO (NMO) crystallized as disc-shaped microsheets, whereas NaCoO (NCO) crystallized as smooth microsheets with surface deposition of polyhedral nanoparticles. The oxides have a surface area of 1.90-2.56 m g. The synthesized adsorbents were studied for low-temperature SO removal in breakthrough studies. The maximum adsorption capacity of 46.8 mg g was recorded for NMO at 70 °C. The adsorption capacity increased with the increasing temperature due to the chemisorptive nature of the adsorption process. The capacity increased with the increasing bed loading and decreasing flow rate due to the improved SO retention time. The elemental mapping confirmed the uniform distribution of sulfur species over the oxide surface. X-ray diffraction showed the absence of metal sulfate nanoparticles in the SO-exposed samples. The X-ray photoelectron analysis confirmed the formation of surface sulfate and bisulfate. The formation of oxidized sulfur species was mediated by hydroxyl groups over NMO and lattice oxygen over NCO. Thus, the work demonstrated here is the first such report on the use of NaMO-type materials for SO mineralization.