FCC catalysts for feeds containing nickel and vanadium

Abstract

A fluid catalytic cracking catalyst made from microspheres that initially contain kaolin, a dispersible boehmite alumina and a sodium silicate or silica sol binder. The kaolin portion contains hydrous kaolin and optionally kaolin which has been calcined through its characteristic exotherm. Calcination of the hydrous clay to metakaolin and formation of in-situ zeolite by treatment with sodium silicate yields a catalyst containing Y-faujasite and transforms the dispersible boehmite into a transitional alumina which contains a gamma alumina phase. The transitional alumina may contain a delta alumina phase as well. The catalyst can be used to crack resid or resid-containing feeds as the alumina phase formed from the dispersible boehmite passivates nickel and vanadium contaminants.

We claim:  
     
         1 . A zeolitic fluid catalytic cracking catalyst which passivates nickel and vanadium during catalytic cracking comprising: 
 (a) at least about 15% by weight Y-faujasite crystallized in-situ from a metakaolin-containing calcined microsphere; and    (b) alumina obtained by the calcination of a dispersible boehmite contained in said microsphere.    
     
     
         2 . The fluid catalytic cracking catalyst of  claim 1 , wherein said alumina comprises a transitional gamma phase.  
     
     
         3 . The fluid catalytic cracking catalyst of  claim 1 , wherein said alumina comprises a combination of transitional gamma and delta phases.  
     
     
         4 . The fluid catalytic cracking catalyst of  claim 1 , wherein said dispersible boehmite is characterized by having at least 90% of said boehmite disperse into particles less than about 1 micron in an acidic media of pH less than about 3.5.  
     
     
         5 . The fluid catalytic cracking catalyst of  claim 1 , wherein said microsphere further contains kaolin calcined through its characteristic exotherm.  
     
     
         6 . The fluid catalytic cracking catalyst of  claim 5 , wherein said kaolin calcined through its characteristic exotherm is spinel.  
     
     
         7 . The fluid catalytic cracking catalyst of  claim 5 , wherein said kaolin calcined through its characteristic exotherm comprises mullite.  
     
     
         8 . The fluid catalytic cracking catalyst of  claim 5 , wherein said kaolin calcined through its characteristic exotherm comprises both spinel and mullite.  
     
     
         9 . The fluid catalytic cracking catalyst of  claim 1 , wherein said Y-faujasite comprises at least about 40% by weight of said catalyst.  
     
     
         10 . The fluid catalytic cracking catalyst of  claim 1 , wherein said Y-faujasite is ion-exchanged to reduce the sodium content of said catalyst to less than 0.7% by weight Na 2 O.  
     
     
         11 . The fluid catalytic cracking catalyst of  claim 1 , wherein said Y-faujasite is ion-exchanged to reduce the sodium content of said catalyst to less than 0.5% by weight Na 2 O.  
     
     
         12 . The fluid catalytic cracking catalyst of  claim 10 , wherein said Y-faujasite is the product of ammonium exchange.  
     
     
         13 . The fluid catalytic cracking catalyst of  claim 10 , wherein said Y-faujasite is exchanged with rare earth cations to provide a rare earth level as REO of 0.1 to 12 wt. %.  
     
     
         14 . The fluid catalytic cracking catalyst of  claim 10 , comprising rare earth levels, expressed as rare earth oxide, REO of 0.5 to 9 wt. %.  
     
     
         15 . The fluid catalytic cracking catalyst of  claim 1 , wherein said Y-faujasite has a crystalline unit cell size of less than 24.7 Å.  
     
     
         16 . The fluid catalytic cracking catalyst of  claim 5 , wherein said calcined microspheres comprise 15 to 85% by weight metakaolin, 5-70% by weight kaolin calcined through its characteristic exotherm and 10-40% by weight of said alumina.  
     
     
         17 . The fluid catalytic cracking catalyst of  claim 16 , wherein said alumina comprises a transitional gamma phase.  
     
     
         18 . The fluid catalytic cracking catalyst of  claim 16 , wherein said alumina comprises a combination of transitional gamma and delta phases.  
     
     
         19 . The fluid catalytic cracking catalyst of  claim 17 , wherein said dispersible boehmite is characterized by having at least 90% of said boehmite disperse into particles less than about 1 micron in an acidic media of pH less than about 3.5.  
     
     
         20 . A method of making a zeolitic fluid catalytic cracking catalyst comprising the steps of: 
 (a) forming an aqueous slurry containing on a dry basis about 15 to 85 parts by weight hydrated kaolin, metakaolin or mixtures thereof, about 5 to 50 parts by weight dispersible boehmite, about 0-85 parts by weight kaolin that has been calcined through its characteristic exotherm, and 5-35% silicate binder;    (b) spray drying the aqueous slurry to obtain microspheres;    (c) calcining the microspheres obtained in step (b) at a temperature and for a time sufficient to convert the hydrated kaolin in the microspheres substantially to metakaolin, but insufficient to cause metakaolin or hydrated kaolin to undergo the characteristic kaolin exotherm;    (d) mixing the microspheres obtained in step (c) with sodium silicate, sodium hydroxide and water to obtain an alkaline slurry; and    (e) heating the alkaline slurry of calcined microspheres to a temperature and for a time sufficient to crystallize at least about 15% by weight Y-faujasite in the microspheres, said Y-faujasite being in the sodium form.    
     
     
         21 . The method of  claim 20 , wherein at least 40% by weight Y-faujasite is crystallized in the microspheres in step (e).  
     
     
         22 . The method of  claim 20 , wherein Y-faujasite seeds are added to the mix of step (d).  
     
     
         23 . A method of  claim 20  including the steps of: 
 (f) separating the micropsheres containing at least 15% by weight Y-faujasite from at least a major portion of its mother liquor;  
 (g) replacing sodium cations in the microspheres separated in step (e) with ammonium ions or ammonium ions and thereafter rare earth ions;  
 (h) calcining the microspheres from step (g) to facilitate release of sodium ions;  
 (i) further exchanging the microspheres with ammonium ions to reduce Na 2 O content to below 1%; and  
 (j) further calcining the microspheres to reduce the unit cell size of the zeolite.  
 
     
     
         24 . The method of  claim 23  in which the rare earth content expressed as rare earth oxide, REO, is between 0.1 wt. % and 12 wt. %.  
     
     
         25 . The method of  claim 24  in which the rare earth content expressed as rare earth oxide, REO, is between 0.5 wt. % and 9 wt. %.  
     
     
         26 . The method of  claim 23  in which the sodium content expressed as Na 2 O is less than 0.7 wt. %.  
     
     
         27 . The method of  claim 23  in which the sodium content expressed as Na 2 O is less than 0.4 wt. %.  
     
     
         28 . The method of  claim 23  in which the sodium content expressed as Na 2 O is less than 0.3 wt. %.  
     
     
         29 . The method of  claim 20 , wherein said dispersible boehmite is characterized by having at least 90% of said boehmite disperse into particles less than about 1 micron.  
     
     
         30 . The method of  claim 20 , wherein said aqueous slurry in step (a) is formed from a first slurry of said kaolin and binder and a second slurry of said dispersible boehmite.  
     
     
         31 . The method of  claim 30 , wherein said second slurry comprises said dispersible boehmite peptized in acid.  
     
     
         32 . The method of  claim 20 , wherein said aqueous slurry in step (a) contains 5-60 wt. % kaolin calcined through the exotherm.  
     
     
         33 . The method of  claim 20 , wherein said binder in step (a) is sodium silicate.  
     
     
         34 . The method of  claim 20 , wherein said binder in step (a) is silica sol.  
     
     
         35 . A method of cracking a resid containing at least 2000 ppm of Ni and V metals comprising contacting said resid with the catalyst of  claim 1 .  
     
     
         36 . A method of cracking a resid containing at least 2000 ppm of Ni and V metals comprising contacting said resid with the catalyst of  claim 5.