Silica-Alumina Cracking Catalyst, 85 % Silica and 15 % Alumina: Water Glass Gelled with Acid, Alumina Precipitated on It (Thomas & Ahlberg, UOP, US 2,285,314)

A catalyst for catalytic cracking: a porous gel of about 85 % silica and 15 % alumina. Water glass is set to a silica gel with acid, washed free of sodium, and alumina is precipitated onto it with ammonia; then it is dried, broken into granules and calcined. Result: a hard granular catalyst. In the patent's test a gas oil passed over it at 932 °F gave 26.4 % of gasoline with a motor octane of 80.7. Burning off the carbon at up to 1400-1600 °F restores it. Source: Thomas & Ahlberg, US 2,285,314 (UOP, 1942), Example I. Not given: ammonia strength, drying temperature. Danger: hydrochloric acid burns. Picture drawn by Youblob.