Study On Promoted Cryogenic Ni-based Hydrodesulfurization Catalyst Water-poisoning For The Claus Tail Gas

In recent years, we keep more and more attention on energy and environmental issues, so more research is studied in the cryogenic hydrodesulfurization Claus tail gas catalysts.On the basis of previous work about cryogenic hydrodesulfurization Claus tail gas catalysts, this paper probes into the water poisoning mechanism. Through a series of method such as the modification of supporter and doping, they can improve the catalyst and active components of the interaction between the carrier.The following conclusion was obtained through aboving experiments:1. The strong inhibiting effect of steam for Ni/γ-Al2O3 catalyst hydrogenation activity leading to the water poisoning is temporary. According to XRD and IR, the cause of water poisoning is that there is competition adsorption effect for water and reactant in the surface of the catalyst, it formed a intermediate intermediate material carbohydrates AlO(OH) and water occupy the active sites of adsorption of reactant, and block the spread of adsorption reactants in the surface, and reduce the surface adsorption energy, thus decreasing the catalytic activity.2. In anhydrous conditions doped Ni-Fe-Al and Ni-Cu-Al will lead to the decreasing of activity. But in the condition of containing 30% water vapor, activities of Ni-Fe-Al-and Ni-Cu-Al are higher than Ni/y-Al2O3 that doesn't dope. The hydrogenation of SO2 percent conversion of Ni-Fe-Al-4 that has strong water-resisting property can reach 100% at 240℃, and Ni-Cu-Al-4 can also up to 92.3% at the same condition. The activity doped Fe is higher then Cu.3. In vapor or anhydrous conditions, the doping of Co and Mo can enhance the activity of catalyst for the hydrogenation of SO2. With high content of Mo, doping Co can enhance the catalytic activity. In anhydrous conditions and at 190℃, the hydrogenation of SO2 percent conversion of Co-Mo-5 catalyst can reach 100%. Under the gas feed containing 30% water vapor, the hydrogenation of SO2 percent conversion of Co-Mo-4 that has strong water-resisting property can reach 100% at 220℃.4. Using Mg modified Ni/γ-Al2O3 catalyst carrier can effectively enhance the resists water performance of catalyst. When Ni:Al:Mg reach one ratio, the lowest temperature that SO2 was completely conversed was 220℃. MgO effectively enhance the resists water performance of catalyst.5. In anhydrous conditions, the hydrogenation of SO2 percent conversion of Ni-based catalyst which is coated and modified by TiO2 can reach 100% at 190℃.In the condition of containing water,it can reach 10% at 220℃. The results show that Al2O3 in the surface of Ni-based catalyst, which is coated and modified by TiO2, barely react with water vapor under the gas feed containing 30%water vapor. And the pore distributionis of catalyst is mainly micropore.