Zn supported on Zr modified mesoporous SBA-15 as sorbents of pollutant precursors contained in fossil fuels: Si/Zr ratio effect

The adsorption processes have become an additional alternative to hydrotreatment processes of oil-derived middle distillates. The crucial point is the type of adsorbent employed. SBA-15 mesoporous materials were used to adsorb quinoline (Q) and dibenzothiophene (DBT) as N- and S-containing model species, respectively, contained in a model mixture mimicking middle distillates. Q and DBT in dodecane solutions (50–250 ppm and 500 ppm, respectively) were used to that end. In order to improve the adsorption properties, SBA-15 was modified, incorporating zirconium at Si/Zr weight ratios of 5, 16, 60, and 150. At those ratios, Q was adsorbed preferably, whereas DBT was removed only below 10%. To increase the amount of S adsorbed, Zn was incorporated at 2 wt. %. At 250 ppm (sol. concentration) of N, the amount adsorbed of Q and DBT on the material without Zn (Si/Zr = 5) was 1.51 and 0.02 mmolg_ads⁻¹, respectively. The results were notably different when Zn was incorporated in adsorbents. In these case, amounts of adsorbed Q and DBT were 2.2 and 1.3 mmolg_ads⁻¹, respectively, showing that metal sites are essential to adsorb DBT.