Study On The Reactive Adsorption Of Sulfide From Model Compound And FCC Gasoline On Supported Metal Oxide

With the development of economy, industry of vehicle developed quickly, the requirement of transportation fuels increased, meanwhile, air pollution caused by automobile exhaust gas become more seriously. Production of clean fuels was needed in order to solve the problem of pollution caused by automobile exhaust gas. Although the conventional hydrodesulfurization (HDS) could effectively remove the majority of sulfur-containing compounds, it was difficult to remove DBT and derivatives, further more, investment of facility was high. Adsorption of sulfur compounds was the common method for removal of these sulfur compounds because of its high performance and low operational costs. It was proved that reaction adsorption had high efficiency in desulfurization. Adsorption desulfurization had been reported to be a complementary and alternative technique for HDS.In this article, NiO, ZnO, CuO, NiO-ZnO and CuO-ZnO were respectively loaded onγ-Al₂O₃ by wet impregnated method. Reaction adsorption desulfurization properties of supported adsorbents on TH, 3-MT, BT and FCC gasoline were investigated. S atoms were fixed on adsorbents by the reaction between metal oxide/metal and sulfur compounds, residual hydrocarbon returned to gasoline. Model compound after reaction were detected. The adsorbents before and after reaction were characterized by XRD, SEM-EDS, XPS and nitrogen adsorption techniques. The probable reaction mechanism and deactivation reason of adsorbents were also discussed.X-Ray diffraction results showed that the maximum monolayer dispersion of NiO onγ-Al₂O₃ was 16%, for CuO and ZnO the value was 12%. NiO had higher dispersion property than ZnO and CuO. Crystal NiO was disadvantageous for reaction. Reactive adsorption performance of sulfur compounds from model compound was researched, the results showed that with the increasing of reaction temperature and decreasing of space velocity, desulfurization efficiency of NiO/γ-Al₂O₃ adsorbent increased. When the reaction temperature was 380℃, space velocity was 4h-1, with the increasing of sulfur compound concentration, desulfurization efficiency of NiO/γ-Al₂O₃ adsorbent on TH, 3-MT and BT decreased, the breakthrough sulfur capacity for each sulfur compound was 0.5767%,0.6313%,1.732%, respectively. It was 12.1 times, 7.2 times and 4.78 times of <60℃fraction, 60⁹0℃fraction and >90℃fraction, respectively. The breakthrough sulfur capacity of NiO/γ-Al₂O₃ adsorbent for multi sulfur compound was 1.327%, it was 7.2 times of gasoline. The desulfurization efficiency for FCC gasoline reduced more greatly than that of model compounds.The desulfurization ability of adsorbent decreased in the order of NiO/γ-Al₂O₃> CuO/γ-Al₂O₃>ZnO/γ-Al₂O₃. The breakthrough sulfur capacity of NiO/γ-Al₂O₃ adsorbent decreased in the order of BT>3-MT>TH; for CuO/γ-Al₂O₃ adsorbent the order was BT>3-MT≈TH. ZnO/γ-Al₂O₃ adsorbent couldn't react with TH, 3-MT and BT. The result of the GC-FPD chromatogram showed that NiO/γ-Al₂O₃ adsorbent had high selectivity on removing of BT from model compound and FCC gasoline.There was certain relationship between reactive adsorption performance of sulfur compounds, breakthrough sulfur capacity and electron density of S. That was, with the increase of electron density, the adsorbent had higher reaction performance and higher breakthrough sulfur capacity. There was much more vacancy in d energy band of Ni; there was no cavity in d energy band of Cu, only had a spot of vacancy in s orbit; there was no vacancy in the d and s orbit of Zn. So NiO/Ni/γ-Al₂O₃ adsorbent had high desulfurization performance, CuO/Cu/γ-Al₂O₃ adsorbent took second place, ZnO/γ-Al₂O₃ had no efficiency on desulfurization.After reaction with sulfur compounds in model compounds and FCC gasoline, C and S were detected on the surface of adsorbents. When removing sulfide from model compound, the C deposition amount increased in the order of TH<3-MT2O₃ adsorbent for BT was 66.57%,57.2% and 45.4%, respectively. In the process of regeneration, adsorbents were placed in high-temperature environment, the loaded active particles could grow gradually and active site would reduce, part of micropore channel may be destroyed, it also led to the decrease of regenerated ratio.