Preparation Of Nanorod Alumina By Seeding Method And Its Application In Hydrodemetallization

Because of the complexity of heavy oil feed-stocks,there are stricter requirements for the performances of residue demetallization(HDM)catalysts and the corresponding carriers.The traditional alumina with inkbottle-like pore has not been satisfactory when used as the carrier of the HDM catalyst for residue.Compared with traditional method,the addition of seed is used as a simple and effective way to improve the progress of the preparation of the alumina nanorod.It has more uniform arrangement and regular morphology.The surface area and pore dimeter become larger.The nanorod aluminum is prepared via hydrothermal method at 200 ~oC for 18hours,and 2 M of aluminum chloride and 1 M ammonia or sodium hydroxide are used as an aluminum source and a base,respectively.The obtained nanorod aluminum has a long rod-shaped morphology(200 nm),size uniform(diameter:30 nm)and larger average pore size(21 nm).And after calcination at 500 ~oC,the surface area and the pore volume of the sample were about 109 m~2/g and 0.43 cm~3/g,respectively.Meanwhile,the surface area and pore structure of the stable alumina rod can be controlled with the different reaction time.NiMo catalyst using nanorod alumina prepared by seeding method as the support showed better catalytic performance for residue HDM than those using nanorod alumina prepared by conversion hydrothermal synthesis and commercial alumina as the support.Under the same reaction conditions,in contrast to the industrial reference agents,residual metal removal rate is higher than 5 percentage points.The results of XRD,BET,H2-TPR,HRTEM and pyridine adsorption IR spectroscopic characterization showed that the acidity and dispersion of Mo S2 over the Ni Mo catalyst prepared by seeding method were similar with those prepared by conversion method and the commercial catalysts.The better HDM performance was ascribed to the rod-shaped morphology,which remained a good pore permeability and uniform size.The larger pore size facilitates the diffusion of the metal porphyrins and other macromolecules in the mass transfer.So the high HDM catalytic activity and stability were obtained over the catalyst.