Synthesis And Catalytic Application Of Modified Mesoporous Alumina Sol

Alumina sol is widely used as catalytic cracking catalysts binder because of its low cost,high thermal stability.After roasting only Lewis acid is in the presence of alumina,so catalysts are very easy to be deactivated because of strong catalytic performance.Br?nsted acid should be introduced into alumina to maintain a good cracking performance.It needs to find new methods to prepare mesoporous alumina sol with Br?nsted acid sites and improve B/L ratio,then improve the overall performance of the cracking catalyst.In this paper,using pseudo-boehmite as the aluminum source,and sol-gel method is used to in the synthesis of alumina sol.In order to prepare alumina sol with Br?nsted acid sites,we researched several modifiers like NH4BF4,Y zeolite structure directing agent,Ti,Zr.Using NH4BF4 as modifier,we can get alumina sol with rich Br?nsted acid sites,the surface area and pore volume of alumina is 233m2/g,0.65cm3/g,respectively.Catalyst prepared with alumina sol modified by NH4BF4 as binder shows better anti-coking performance than those using conventional alumina sol and silicon sol as binder,and the yields of liquefied petroleum gas,propylene and butylene were higher.The surface area and pore volume of alumina modified by Y zeolite structure directing agent is 320m2/g,0.72cm3/g,respectively.Optimization of conditions was carried out through single factor experiment: reaction time 6h,reaction temperature 80?,roast temperature 600?,roast time 4h,age time 8h.Ti,Zr and silica sol shows moderation of the alumina acidity,due to excess modifier the crystal phase of alumina will change.