Synergistic effects of MOF-76 on layered double hydroxides with superior activity for extractive catalytic oxidative desulfurization

Abstract

The combination of metal–organic frameworks (MOFs) with layered double hydroxides (LDHs) has been greatly limited by the agglomeration of pure MOFs and the height of the LDH gallery, so there are few reports on the combination of MOFs and LDHs. In this work, for the first time, the combination of MOF-76 with a layered double hydroxide (MOF-76@LDH) was used for desulfurization under room temperature and pressure conditions without the necessity of protecting with nitrogen. The structure of the heterogeneous catalyst was characterized using FT-IR, XRD, TG, BET, SEM, EDX, XPS, fluorescence and ICP-AES. The as-prepared catalyst exhibited superior activity in deep desulfurization of DBT (dibenzothiophene), BT (benzothiophene) and 4,6-DMDBT (4,6-dimethyldibenzothiophene). The above sulfides could be completely converted into their corresponding sulfones and sulfoxides at 60 °C in 25, 40 and 55 minutes, respectively. 49 wt% MOF-76@LDH exhibited a high desulfurization capacity (100%), much higher than that of LDH (16.3%), MOF-76 (48%) and MOF-76 + LDH (50.3%). Because MOF-76@LDH has a special one-dimensional channel on the surface of the material, it can efficiently promote the degradation of H₂O₂ into hydroxyl radicals (˙OH) and further improve the desulfurization effect. The catalyst is easy to recycle and can be reused at least 5 times, and the catalytic effect is not significantly reduced. This provides a completely new route for the synthesis of MOF–LDH advanced functional materials.