Study Of Preparation Of Large Pore Volume Pseudo-boehmite

Hydrogenation is an important process in oil refining.Hydrogenation Catalysts carrier mainly used y-Al2O3,the precursor of which is mostly Pseudo-boehmite.As light oil demand increasing and crude oil becoming heavier,more attention is being paid to heavy oil hydrogenation technique and residuum hydrogenation technique.γ-Al2O3 with large pore volume provides an effective solution to the large diffusion resistance of the heavy oil component in the catalyst pore,and the deposition and coking of heavy metals in the catalyst pore.Therefore,the development of the preparation of large pore volume pseudo-boehmite technology has broad application prospects.After capacity expansion revamping of PB in the Changling branch of Sinopec Catalyst Company,the defects which were low pore coincidence rate,low production yield and poor stability of product quality appeared.On the basis of analysis of the defects,the paper mainly studied the pore structure of PB in each process,the colloid forming conditions of preparing PB and the property of sodium meta-aluminate.In the research of the PB pore structure of each step,the structure of PB in gel forming also was fairly loose.Its pore volume and specific surface area were lower.More stable structure of the primary particles was formed after a certain time of the aging and the slurry process.The hole volume and specific surface rapidly increased.Extended aging and slurry total time contributes to the PB structural stability and pore volume increase.The optimum total time for aging and slurry process is 10～12h.In this research,the pseudo-boehmite has been prepared by NaAlO2-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,specific surface area and the filtration performance of the PB serous fluid.The result indicated that:(1)With the increase of pH,the filtration performance of the PB serous fluid increased,and then decreased.The PB serous fluid at pH of 8.0 had highest filtration performance.PB crystallinity become better at first and further becomes worse with the increase of pH.The surface area and the pore volume of γ-Al2O3 increased significantly.When the pH of PB serous fluid was about 10.0,the surface area decreased significantly and the pore volume decreased slightly.(2)With the increase of gelation temperature,the filtration performance,the crystallinity and the pore volume increased significantly.(3)Higher gelation temperature,higher the aging temperature and higher the washing temperature of the slurry had a higher filtration performance.The UV absorption spectrum of the sodium meta-aluminate indicated that:the property of sodium meta-aluminate was related to concentration,caustic ratio outside,preparation method,storage time,and the degree of hydrolysis.With the decrease of the sodium meta-aluminate temperature,the Al2O3 concentration continued to decrease and the caustic ratio continued to rise.When the temperature dropped to 65 degree,small white particles precipitated and the sodium meta-aluminate solution was turbid.This innovation of partial sodium high temperature storage,low temperature using was feasible.Aluminum trihydroxide content was controlled.The pore volume was improved.Through the research,the changes of the PB pore structure in each process was understood,the poor stability of PB quality was solved,and the productivity of PB was increased.The research laid a solid foundation for the production of 460 tons Qilu residue hydrotreating catalyst and 580 tons Hainan residue hydrotreating catalyst.