Method of making co-precipitated silica-alumina catalyst

Claim 1

A PROCESS FOR CONVERTING HIGHER BOILING HYDROCARBONS TO GASOLINE HYDROCARBONS WHICH COMPRISES CONTACTING A HIGHER BOILING HYDROCARBON OIL UNDER CONVERSION CONDITIONS OF TEMPERATURE AND PRESSURE TO EFFECT THE DESIRED EXTENT OF CONVERSION WITH A SILICA ALUMINA CATALYST CONTAINING BETWEEN ABOUT 20% AND 50% ALUMINA AND THE REST SUBSTANTIALLY SILICA PREPARED BY FORMING A SILICA HYDROSOL HAVING A PH BETWEEN ABOUT 3,5 AND 5.5, EFFECTING ONLY LIMITED POLYMERIZATION OF SAID SILICA HYDROSOL WITHOUT CAUSING GELATION THEREOF AND MAINTAINING SAID SILICA HYDROSOL AS A CLEAR SOL BY HOLDING IT AT A PH BETWEEN ABOUT 3.5 AND 5.5 FOR A PEROOD OF TIME EQUAL TO ABOUT ONE-HALF THE SETTING TIME OF SIAD SILICA HYDROSOL, THEN SUBSTANTIALLY REDUCING FURTHER POLYMERIZATION OF SAID SILICA HYDROSOL BY ADDING AN ACIDIC AQUEOUS SOLUTION OF ALUMINUM SULFATE THERETO TO REDUCE THE PH OF THE RESULTING SOLUTION TO BETWEEN ABOUT 1.0 AND 3.0 AND THEN ADDING TO SAID SOLUTION AN AQUEOUS AMMONIA SOLUTION WHILE AGITATING THE RESULTING SOLUTION TO RAISE THE PH THEREOF TO ABOUT 7.0 TO EFFECT FORMATION OF HYDROGEL PARTICLES FROM THE POLYMERIZED SILICA HYDROSOL AND PRECIPITATION OF ALUMINA AND COMBINATION OF THE ALUMINA AN SILICA WHILE CONTINUILNG THE AGITATION TO FORM AN AQUEOUS SLURRY OF HYDROGEL PARTICLES OF SILICA-ALUMINA COMPOSITE, DEWATERING THE SLURRY TO RECOVER SILICA-ALUMINA COMPOSITE PARTICLES AND DRYING, WASHILNG AND REDRYING SAID RECOVERED SILICA ALUMINA COMPOSITE PARTICLES TO PRODUCE SAID SILICA-ALUMINA CATALYST.