Zeolites for adsorptive desulfurization from fuels: A review

Removal of aliphatic and aromatic sulfur compounds from fuel by adsorption on zeolites, has been reviewed. Zeolites can be loaded with different metal ions such as Fe2+, K+, Ag+, Cu+, Ni2+, Zn2+, and Ce4+ and Pd2+ via ion exchange or impregnation methods. Modified zeolites with these metal ions increase their adsorption capacity and selectivity. Specially, Ce4+ and Pd2+ shows a selectivity towards the sulfur compounds in the presence of the other compounds such as aromatics, O-containing fuel additives and nitrogen compounds. Three types of adsorptive desulfurization include reactive adsorption, selective adsorption, and pi-complexation have been used by zeolites for the removal of sulfur compounds. Thermal and solvent regeneration of zeolites in adsorptive desulfurization process have been discussed in detail. Adsorption methods of the sulfur compounds on the zeolite, the charge of metal cations, texture properties of the zeolite, the numbers of active sites on the frameworks of zeolite, acid properties of zeolites, SiO2/Al2O3 ratio and the pore size have a significant impact on the adsorption of sulfur compounds. X and Y zeolites have been widely studied for adsorption of sulfur compounds, due to their tuneable selectivity regarding polar molecules and pore size. Zeolites have been shown good sulfur loading capacity, good regenerability and stable structure for removal of sulfur compounds. (C) 2017 Elsevier B.V. All rights reserved.