Remarkable adsorptive removal of nitrogen-containing compounds from hydrotreated fuel by molecularly imprinted poly-2-(1H-imidazol-2-yl)-4-phenol nanofibers

Perspectives on strategies for improving ultra-deep desulfurization of liquid fuels through hydrotreatment: Catalyst improvement and feedstock pre-treatment

Reliance on crude oil remains high while the transition to green and renewable sources of fuel is still slow. Developing and strengthening strategies for reducing sulfur emissions from crude oil is therefore imperative and makes it possible to sustainably meet stringent regulatory sulfur level legislations in end-user liquid fuels (mostly less than 10 ppm). The burden of achieving these ultra-low sulfur levels has been passed to fuel refiners who are battling to achieve ultra-deep desulfurization through conventional hydroprocessing technologies. Removal of refractory sulfur-containing compounds has been cited as the main challenge due to several limitations with the current hydroprocessing catalysts. The inhibitory effects of nitrogen-containing compounds (especially the basic ones) is one of the major concerns. Several advances have been made to develop better strategies for achieving ultra-deep desulfurization and these include: improving hydroprocessing infrastructure, improving hydroprocessing catalysts, having additional steps for removing refractory sulfur-containing compounds and improving the quality of feedstocks. Herein, we provide perspectives that emphasize the importance of further developing hydroprocessing catalysts and pre-treating feedstocks to remove nitrogen-containing compounds prior to hydroprocessing as promising strategies for sustainably achieving ultra-deep hydroprocessing.

Methylcellulose/tannic acid complex particles coated on alginate hydrogel scaffold via Pickering for removal of methylene blue from aqueous and quinoline from non-aqueous media

Adsorbents reported for liquid phase decontamination under both aqueous and non-aqueous media are all dispersed phase sorbents that further require a tedious separation step post adsorption. Herein, a monolith, highly porous, and mechanically robust scaffold was synthesized for the adsorption of pollutants from both aqueous and non-aqueous media with facile separation and regeneration. Methylcellulose-tannic acid complex particles were prepared and systematically decorated on the surface of interpenetrating polymer network (IPN) scaffold via Pickering emulsion. Due to the surface coating of the particles, plausible amphiphilic adsorption of quinoline (QUI) and methylene blue (MB) was achieved from fuel and water, respectively. The hydroxyl (OH-) and carboxyl (COOH-) groups of tannic acid, alginate, and polyacrylic acid created hydrogen bonding, electrostatic interaction, acid-base interaction, and π-π stacking. Maximum adsorption capacity of 791.17 mg/g MB and 460.92 mg/g QUI was recorded with facile separation, excellent adsorbent regeneration, and reusability. Although both followed the pseudo-second-order adsorption kinetic model, a different mechanism was identified to govern the adsorption under aqueous and non-aqueous environment i.e. only the surface particles were active for QUI adsorption while the scaffold was also involved for MB adsorption.

Adsorptive denitrogenation of fuel over molecularly imprinted poly-2-(1H-imidazol-2-yl)-4-phenol microspheres

Molecularly imprinted poly 2-(1H-imidazol-2-yl)-4-phenol prepared by suspension polymerization of 2-(1H-imidazol-2-yl)-4-vinylphenol in the presence of selected nitrogen containing compounds showed adsorption selectivity for target nitrogen-containing compounds in fuel oil.