Enhancing Adsorption Desulfurization Performance Using Enriched Cu(I) Sites over Microenvironment-Modulated HKUST-1.

High-efficiency adsorption of aromatic sulfur-containing compounds from liquid hydrocarbon fuels over metal-organic frameworks (MOFs) is challenging because of inert metal sites. A new method, the Ce-enhanced modulation of MOFs' microenvironment, is proposed to modulate the -COO···Cu(II)- coordination microenvironment of Hong Kong University of Science and Technology (HKUST-1) using Ce(III) as a molecular scalpel for fabricating abundant high-efficiency Cu(I) and Cu-coordination-unsaturated sites and improving the pore structures around adsorptive sites. The optimal CH-250 thus exhibits adsorptive capacities for 20.2, 28.0, and 58.3 mg S g-1 of thiophene, benzo-thiophene, and dibenzothiophene, respectively, which are superior to most reported MOFs, zeolites, and nanoporous carbons. The constructed Cu(I) sites show stronger affinity for dibenzothiophene (-0.86 eV) than the initial Cu(II) (-0.74 eV) for out-of-plane adsorption. Further, they are far stronger in-plane adsorption interactions in DBT/CH-250 (-0.90 eV) than those in DBT/HKUST-1 (-0.37 eV). Thus, molecular engineering for modulating the coordination microenvironment of MOFs shows great potential for adsorption desulfurization.