Cu-based metal–organic framework/activated carbon composites for sulfur compounds removal

MOF-199 was modified by incorporating activated carbon (AC) during its synthesis under hydrothermal conditions to improve its performance in the removal of hydrogen sulfide (H 2 S) and dimethyl sulfide (CH 3 SCH 3 ). A variety of different characterization techniques including X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, nitrogen adsorption/desorption isotherms, scanning electron microscopy (SEM), pyridine adsorption infrared spectroscopy (Py-IR), thermogravimetric- mass spectroscopy (TG-MS) and X-ray photoelectron spectroscopy (XPS) were used to analyze the fresh and exhausted composites. It was found that the composites, which have an amount of AC of less than 2%, had the same morphology as those of pristine MOF-199, but exhibited a more ordered crystallinity structure as well as higher surface area. The composite with 2% AC incorporation showed highest sulfur capacity of 8.46 and 8.53% for H 2 S and CH 3 SCH 3 , respectively, which increased by 51 and 41% compared to that of MOF-199. This improvement was attributed to the formation of more micropores and especially the increased number of unsaturated copper metal sites, as revealed by Py-IR. It is suggested the chemical reaction was apparent during adsorption of H 2 S, which resulted in the formation of CuS and the collapse of the MOF structure. Whereas reversible chemisorption was found for CH 3 SCH 3 adsorption, as testified by TG-MS and fixed-bed regeneration. Exhausted MAC-2 can be almost totally regenerated by high temperature 180   °C nitrogen purge, indicating a promising adsorbent for CH 3 SCH 3 removal.