Aviation Gasoline by Catalytic Cracking over Silica-Alumina Gel at 750 °F (Voorhies, US 2,230,552)

Oil vapour passed over a hot silica-alumina gel cracks into gasoline of relatively high octane number. Voorhies (Standard Oil Development, 1941) showed that a light feed cracked at a low temperature, about 750 °F, gives aviation gasoline that needs little or no further refining. Best result in the patent (Ex. 1, a light crude cut boiling 336-540 °F): 25.9 % of the feed as aviation gasoline (the table says 25.0 %), ASTM octane 81.0 clear and 91.7 with 3 cc of tetraethyl lead per gallon. Variables: the feed, the temperature and the feed rate. Hotter and faster gives less gasoline and more unsaturates. Source: A. Voorhies Jr., US 2,230,552 (1941). Not given: reactor design, how the catalyst is regenerated, catalyst amounts. Highly flammable vapours. Picture: catalytic cracking units in Louisiana, about 1944 (FSA, public domain).