GB872310A - Liquid fuel compositions - Google Patents

Abstract

Anti-knock performances of leaded or unleaded gasolines having an original performance number of at least 90 (97 octane number) are improved by the addition of one or a mixture of compounds selected from sodium and potassium salts of organic carboxylic acids containing from 4 to 18 carbon atoms. Aliphatic and cycloaliphatic acids with or without aromatic substitution are exemplified by 2-methyl- and 2,2-dimethyl-propionic acids; 3-methyl-3-phenyl-, 2-methyl-, 2,2-dimethyl-, and 3 - methyl - 3 - cyclohexyl - butanoic acids; 2,2,4,4-tetramethyl-, 2,3-dimethyl-, 2-ethyl-4-methyl-, and 2-propyl-4-methyl-pentanoic acids; 1,2,2,3-tetramethyl-cyclopentane carboxylic acid; 3,5,5-trimethyl-, 2-ethyl-, 2,2-diethyl-, 2-methyl-, and 4,5-dimethyl-hexanoic acids; 1-methylcyclohexane-1-carboxylic acid; naphthenic acids derived from petroleum; oleic acid; and undec-10-en-1-oic acid. The compounds are normally introduced with the fuel into the engine cylinder but may be introduced therein separately as a powder or with solvents, e.g. in water/alcohol mixtures for aircraft engines or tetraethyl lead/alcohol mixtures for automotive engines. A fuel of performance number 90 is one whose knock resistance by the F-1 Research Method (ASTM D-908-51) is equal to or greater than the knock resistance of a blend consisting of 97% isooctane and 3% n-heptane. The compounds of the invention, which are used in amounts equivalent to 0.05 gram to 5.0 grams of sodium or potassium metal per U.S. gallon of fuel, are effective in unleaded fuel and in fuels containing up to 6.0 ml. of tetraethyl lead per U.S. gallon. Conventional fuel additives such as dyes, antioxidants, &c., may be incorporated into the fuel. The solubility of the sodium and potassium salts in the fuel is enhanced by the use of blending agents such as alcohols, glycols, esters, ketones, and amides. In examples isopropanol is used as blending agent.