The Synthesis Of Mesoporousalumina Sol With Rich Bronsted Acid Sites And Its Application In FCC Catalyst

Fluid catalytic cracking is an important process in crude oil secondary processing as wellas a core technology of refining enterprise. Alumina sol is widely used as catalyst binderbecause of its low cost and high thermal stability. But some problems still exist. First, poorchannel connection of conventional alumina sol affects the mass and heat transfer capability.Second, after the roasting dehydration of Alumina sol, the Bronsted acid center is translatedinto Lewis acid center. Bronsted acid is the cracking center of reaction while Lewis acid is thecoked center. Bronsted acid is the ideal acid center for catalyzing so it is necessary to explorenew prepararion methods to improve the structure and performance of alumina and to ajustthe B/L acid ratio on the surface. Finally we can enhance catalyst overall connectivity, reducethe mass and heat transfer resistance and lower coke selectivity.In this paper, sol-gel method is used in the synthesis of alumina sol.Using boehmite asthe aluminum source, we examined the moderate effect on alumina acidic bits of differentmodifiers like TEOS, ammonium fluoroborate and ammonium fluosilicate. Alumina sol withrich Bronsted bits is prepared and the specific surface area and pore volume are raisedsignificantly. Modifers show more influence on the alumina structure than pH, type anddosage of the template agents do.According to the results, NH₄BF₄shows a better moderationof the alumina acidity and little effect on the colloid binding performance. During theevaluation process, VGO is used as the raw oil. Catalyst prepared with mew aluminum sol asbinder shows higher light oil yield and conversion rate and better anti-coking performancethan those using conventional alumina and silicon sol as binder.