Researches In Preparation And Property Of Alumina Sol In FCC Catalysts

In this thesis, aluminum sols are prepared by process AlCl₃and process Al-AlCl₃,whichare transparent, stable and satisfied the requirements of FCC catalyst. The pH, the viscosity,and the content of Al and Cl of the sols which are prepared by the technologies of AlCl₃'sprocess and Al-AlCl₃'process are2.63,5.7mPa·s,10%,10%;2.54,7.4mPa·s,10%,10%,respectively.Compared with the traditional Al-HCl technology, our method of process AlCl₃will notgenerate hydrogen and large amounts of reaction heat. At the same time,this technology caneliminate the hidden danger of security and reduce the corrosion of equipment. The procedureof process Al-AlCl₃can also reduce the production of hydrogen by more than67%, anddecrease reaction heat greatly. The stability of aluminum sols prepared by the two methodsstated above is much higher than the tranditional production.In this study, we describe a non-uniform precipitation method to prepare aluminum solin the library, which use AlC13·6H₂O and NH₃·H₂O as the raw materials. The studysystematically focuses on the effects of the precipitation temperature, aging time, geltemperature, gel time, the aluminum content, the precipitation agent and the inorganicaluminum salt's species and concentration on the viscosity, the pH and the stability of thealuminum sol. The main conclusions are as follows:1. The preparation of the transparent aluminum sol depends on the kinds of precipitationagent and inorganic aluminum salt. The stable and transparent sol can be got when usingNH₃·H₂O and AlCl₃·6H₂O as the precipitation agent and inorganic aluminum salt respectively.2. Controlling precipitation temperature can preparation different aluminum sol duringprecipitation process. Only at the room temperature, we can get the amorphous precipitationof Al(OH)₃and stabable and transparent sols.3. The viscosity of the sol increases with the extension of aging time of theprecipitation. The white translucent gel is prepared after aging12h.4. The gel temperature and gel time of Al(OH)3reacted with AlCl₃solution has a greateffect on the viscosity, pH, stability of the sol. The viscosity of the sol increases with the riseof the gel temperature. When the temperature increases to90℃, the solution boiled, and thesol changes into gel, the pH reduce at the same time. The absolute values of Zeta potential ofthe sol are30mV or so,they are stable sol system, but the stability decreases withtemperature increaseing. In adition, the viscosity increases with the gel time extending, butthe pH, and the stability reduces with the gel time extending. 5. The viscosity, pH and electrochemical properties are depended on the contentof Al. If the aluminum content is very low, the sol won't suit for FCC catalyst. Theviscosity of sol is increasing with the content of aluminum'increasing, while the pHand the stability reduced. It is not suitable for use when the content increases to12%,the viscosity is32mPa·s, which liquidity is bad.