Performance Of Hds Catalyst And Preparation Of Zn₂TiO₄ As Additive Of Catalyst

Nowadays, protection of environment has received more attention. So sulfur content in fuels is required lower and lower. Only demanding the operating conditions deeper can remove more refractory sulphide, but this will inevitably lead to increase the costs. Therefore, starting with the catalyst and optimizing the operating condition, to achieve deep HDS process under low temperature and pressure, becomes a hot spot now. In addition, the catalyst which Zn₂TiO₄ is added exhibits substantial activity for hydrodesulfurization. The difficult point is to invent a simple and efficient method to prepare pure Zn₂TiO₄ nano-particles.The pore volume ofγ-Al₂O₃ used in the experiment was 0.552 ml/g. Catalysts, in which the contents of ZnO、NiO and MoO₃ were different,were prepared by step-impregnation. Under different operating temperature, pressure, feed flow and initial concentration, thiophene-hexane system was used to simulate practical fuels to test the activity of catalysts in the high pressure hydrogen device. Also, the catalysts were characterized by BET, XRD, SEM, TEM and EDS. The catalyst which contained 15 % ZnO、1.5 % NiO and 3.5 % MoO₃ exhibited highest stability and activity. When the operating condition was 320℃, 1.5 MPa, feed flow 1.0 ml/min, the catalyst removed the sulfur content from 2400 ppmv to 8.7 ppmv which has already achieved EuropeⅤstandard. Under the same condition, industry catalyst A only removed the sulfur content to 61.3 ppmv.Zn₂TiO₄ was prepared by precipitation method in membrane dispersion mini-reactor using zinc nitrate and titanium sulfate as materials, ammonia or ammonium bicarbonate as precipitant. Ti⁴⁺ would be precipitated as titanic acid while pH value was 2.33. After increasing pH value to 4.08⁵.03, the precipitation of Zn²⁺ would be generated and reacted with titanic acid to product zinc titanate. High pH value would make zinc titanate tending to be ZnTiO₃ irreversibly. Using ammonium bicarbonate as dispersion phase and premixing process could effectively avoid the formation of ZnTiO₃. This process could prepare pure Zn₂TiO₄ after washing with dilute sulfuric acid and the control range became wider. When the sum of the feed flows of two phases was 20 ml/min, the particle size was 25.21 nm and the surface area was 54.83 m²/g.In this study, we achieved deep HDS process under low temperature and pressure. In addition, we invented a simple and efficient method to prepare pure Zn₂TiO₄ nano-particles.