Cracking catalyst

Claim 1

METHOD FOR RENDERING CRACKING CATALYST MORE RESISTANT TO ATTRIBUTION WHILE EMPLOYING THE CATALYST IN THE CRACKING OF HYDROCARBON OIL, WITH SUBSEQUENT REGENERATION OF THE CATALYST BY BURNING CARBON DEPOSITS THEREFROM, WHICH COMPRISES CONTACTING GRANULAR SOLID CRACKING CATALYST SELECTED FROM THE GROUP CONSISTING OF SYNTHETIC SILICIAALUMINA, SILICA-MAGNESIA, SILICA-ZIRCONIA, SILICA-ALUMINAMAGNESIA AND SILICA-VANADIA CRACKNG CATALYST AND ACTIVATED CLAY CRACKING CATALYST WITH A SLURRY OF COMMINUTED LIMESTONE CONTAINING AT LEAST 50% CALCIUM CARBONATE AND AT LEAST 10% MAGNESIUM CARBONATE IN HYDROCARBON OIL AT A TEMPERATURE IN THE RANGE FROM 400 TO 550*C. IN A CRACKING ZONE TO PRODUCE GASOLINE, THE AMOUNT OF LIMESTONE BEING IN THE RANGE FROM 0.2 TO 1 POUND PER TON OF CATALYST PER DAY, AND SUBSEQUENTLY BURNING CARBON DEPOSITS FROM THE CATALYST PARTICLES IN A REGENERATING ZONE TO OBTAIN REGENERATIED CATALYST PARTICLES HAVING A GLAZE ON 10 TO 60% OF THE TOTAL EXTERIOR SURFACE AREA OF THE PARTICLES.