Study on thiophene desulfurization mechanism over vanadium oxides under FCC condition

The reaction mechanism of thiophene on vanadium oxides under FCC operating conditions was studied using TPSR-MS method and continuous fixed-bed reaction, followed by characterization via IR pyridine adsorption-TPD method and XPS spectra. Conversion of thiophene on V₂O₅ at 500°C, a space velocity of 33.43/hr, and a catalyst/oil ratio of 1.54:1 could reach 15.9 wt %, including 12.4 wt % of sulfur converted into H₂S. Conversion of thiophene during its reaction on single Lewis acid centers was very low. At 500°C, thiophene could enter into redox reaction with V₂O₅ and V₂O₄, which after losing some crystal lattices could be reduced into products with lower valence state such as V₂₃, while thiophene was oxidized into CO, CO₂, and SO₂. The SO₂ yield resulted from reaction of thiophene on V₂O₅ was much higher, because V₂O₅ had a stronger oxidizing ability. A few Bronsted acid sites existing on the surface of V₂O₅ resulted in a significant increase of H₂S yield among the products derived from the reaction of thiophene. This is an abstract of a paper presented at the 231st ACS National Meeting (Atlanta, GA 3/26-30/2006).