Study Of Catalytic Materials For Hydrotreating Of Heavy Oil

Active alumina is playing an important part in the field of hydrogenation process due to its perfect surface area as well as its pore structure and surface acidity. As the worldwide supply of light crude oil decreases, more attention is being paid to heavy oil hydroprocessing technique.For the purpose of long-life and highly activity hydrotreating catalysts ,theγ-alumina support should have large pore volume,suitable pore distribution.In this research, the pseudo-boehmite has been prepared by Al₂(SO₄)₃ method .The nitrogen adsorption, XRD etc. technique were used to determine the influences of the preparation condition on pore structure such as crystallography, average pore diameter, pore volume and specific surface area.The result indicates that: The crystallography is decided by the pH value in the preparation; pseudo-boehmite with high purity is obtained when the pH value is in the range of 6.5⁸.5;Under high temperature and high pH,the product with large pore diameter can be gained; with the increasement of temperature and pH,the specific surface of pseudo-boehmite decreased; In aging step, pronging aging time and increasing temperature are propitious to improve crystallinity and pore volume;But if the pseudo- boehmite were prepared at high temperature and high pH, the influence of aging is little.On the base of preparation pseudo-boehmite with the Al₂(SO₄)₃ method. the modified alumine were prepared by adding promoter compound including phosphoric acid, sodium silicate and boric acid, to study the effects of different additives on the properties of Al₂O₃. Several conclusions arrived below.The crystallinity of alumina decreases with the increase of phosphorus content. The addition of a little phosphate could effectively improve the specific surface area and pore volume. When the phosphorus is excessive, the specific surface area and pore volume decreases obviously. But the average pore diameter persistent enlarge with the increase of phosphorus content. The style of surface acidity was unchanged with the addition of phosphoric acid, but the total acid decreased. The proportion of weak acid decreases while the strong acid medium acid proportion increases.The addition of Si and B into the alumina has little effect on the crystal phase, the Si made specific surface area increases obviously at the same time average pore diameter decreases obviously; the surface acidity has little change. Small amount of boron resultes in a slight increases in both pore diameter and pore volume. Further incorporation of boron into the alumina resultes in a decrease in pore diameter and pore volume, the surface area change with boron content was irrespective. Boron also improves the gross of surface acidity of alumina.We choose the P and Si modified pseudo-boehmite as the carrier materials followed the request of hydrotreating catalysts for heavy oil. Then prepared Ni-Mo-W/Al₂O₃ catalyst for FCC feedstocks. The catalyst was evaluated using the SINOPEC Qingdao Company VGO as feedstock. The results show that HDS and HDN of FCC diesel oil is 96.8% and 92.0% respectively, at the condition of 380℃, 10Mpa, LHSV 1.5h^-1, H2/oil 700/1(V/V).