In situ formation of a multiporous MOF(Al)@γ-AlOOH composite material: A versatile adsorbent for both N- and S-heterocyclic fuel contaminants with high selectivity

Abstract We report here for the first time an in situ green synthetic approach for the formation of a multiporous (mesoporous) composite, Al(OH)(1,4-NDC)@γ-AlOOH, via a direct hydrothermal reaction between 1,4-H 2 NDC (1,4-naphthalene dicarboxylic acid) and millimeter-sized porous γ-Al 2 O 3 beads. This composite material has been well characterized using various analytical techniques. It has been used for the stationary solid phase adsorption of sulfur-containing (SCCs) and nitrogen-containing compounds (NCCs) from both a model oil and a real fluid cracking (FCC) oil. The adsorption capacities decreased in the order of benzothiophene > dibenzothiophene > 4,6-dimethyldibenzothiophene > thiophene for the SCCs and pyridine > quinoline > indole > acridine for the NCCs. The composite material exhibited chemical stability, mechanical strength and recyclability for both the model oil and the real FCC oil. It is an active heterogeneous adsorbent for heterocyclic SCCs and NCCs with a high selectivity for aromatics. By using 2 g of this material, 97.4% (C i  = 77 ppmw N ) and 58.3% (C i  = 350 ppmw S ) for NCCs and SCCs, respectively, were removed from 20 g of real FCC oil in 2 h at ambient conditions. The main factors accountable for this excellent adsorption are the multiporous structure of the material with its enhanced surface area and porosity, its unique structural interactions, specific pore size and the presence of unsaturated Lewis acid metal (Al) sites.