3841. VOORHIES, A. (Standard Oil Development Co.). Catalytic Improvement of Hydrocarbon Synthesis Product. United States Patent 2,600,452, June 17, 1952; appl. filed July 1, 1947, Serial No. 758,329; 8 claims (Cl. 260-450). Chem. Abs., vol. 46, 1952, p. 8360.

Octane number of synthetic gasoline produced from CO and H₂ over an Fe catalyst is raised by passing the gasoline in the vapor phase at 900°-950° F. and a space velocity of 2-5 vol. of 2-5 vol. of cold oil per vol. of catalyst over a spent SiO₂.-Al₂O₃ cracking catalyst composed of SiO₂ 86-88 and Al₂O₃ 12-14, and containing Fe 0.3-1 part by weight. The catalyst should have an activity index (D+L value) < 20. The activity index is measured by cracking gas oil for 2 hr. at 850° F. over the catalyst at a space velocity of 0.6 vol. of oil per vol. of catalyst per hr., distilling 100 vol. of the product b. up to 400° F.., determining the vol. of overhead distillate (D) and residue (L) and subtracting D+L from 100. Treatment of a synthetic gasoline raised its research octane No. from 80 to 94.1 and the motor octane No. from 80 to 94.1 and the motor octane No. from 68.6 to 81.1. The improvement is due to the isomerization of the olefins present in the synthetic gasoline by shifting their double bond from the 1 position to the center of the molecule.