Adsorption of Nitrogen-Containing Compounds from Model Fuel over Sulfonated Metal–Organic Framework: Contribution of Hydrogen-Bonding and Acid–Base Interactions in Adsorption

Abstract

Adsorptive denitrogenation (ADN) was carried out by adsorption of indole (IND) and quinoline (QUI) over metal–organic frameworks (MOFs) including acidic UiO-66—SO3H for the first time. The adsorbed amount of IND increased with increasing content of —SO3H in UiO-66. The favorable effect of the —SO3H group on the adsorptive removal of IND could be explained by hydrogen bonding between the O of —SO3H and the H of IND, which was firmly supported by the adsorption of pyrrole and methylpyrrole and by theoretical calculations. The application of an —SO3H group in the adsorptive removal of neutral IND is meaningful since neutral nitrogen-containing compounds are not easy to remove and since UiO-66—SO3H is reusable after simple washing with ethanol. The expected increase in QUI adsorption (due to acid–base interaction) with acidic —SO3H was observed when QUI was present at low concentrations (<∼400 ppmw). This favorable contribution of acidic —SO3H to the adsorption of basic QUI was also supported by calculations ...