Sulfur Compounds Adsorption from Diesel Fuel by Zeolitic Tuff

The removal of organosulphur compounds (ORS) from diesel fuel is an important aspect of Jordanian's effort to reduce air pollution. Currently, the total sulphur content in Jordanian diesel fuel is 12000ppmw (1.2%, wt/wt), but Jordanian government has recently introduced new restrictions that will reduce this level gradually to internationally acceptable levels. The zeolitic tuff (ZT), from Tlul Al-Shahba region, was characterised using various analytical techniques. It was found that the Freundlich model fitted the adsorption isotherms more accurately than the Langmuir model; indicating that the ZT had a heterogeneous surface. The Langmuir adsorption capacity values for the three particle size ranges (100-200), (300-400), and (500-600) _mwere 7.15, 6.32, and 5.52 mg/g and the column capacities were 4.45, 2.57, and 1.92 mg/g, respectively. The spent ZT was regenerated by washing with n-heptane with an efficiency of 81.5%. Two adsorption mechanisms were investigated. One is that the interaction of thiophene with the Brnsted site of the ZT through S atoms; the other is via C-S bond cleavage in thiophene-derived carbocations to form unsaturated fragments on the Brnsted acid sites.