GB867884A - Liquid fuel compositions - Google Patents

Abstract

Improved engine efficiency and knock resistance in internal combustion engines are obtained by the use of a leaded or unleaded hydrocarbon fuel of the gasoline boiling range having an original performance number of at least 90 and containing a lithium salt of a carboxylic acid of 5-18 carbon atoms the carboxylic acid group being attached to a methylene group and the acid molecule containing at least one carboxylic ring. The performance number of at least 90 (97 octane number) is that measured by the F-1 Research Method (A.S.T.M. D-908-51). Acids from which the lithium salts are derived are exemplified by the cyclo-propyl, -butyl, -pentyl, 3,3,4 - trimethyl - cyclopentyl, 1 - acenaphthyl and 4-tert. butylphenyl derivatives of acetic acid; 3-cyclopentyl- and 3-(11-decahydronaphthyl)-propionic acid; 3-phenyl-, 3-phenyl-3-methyl-, 3-cyclohexyl-3-methyl-, and 3-cyclohexyl-3-ethyl-butanoic acid; and napthenic acids derived from petroleum. Mixtures of salts may be employed. The fuel and additive may be introduced separately into the combustion chamber of the engine cylinder, the additive being in powder form or in a supplementary antiknock solution, e.g. the water/alcohol and tetraethyllead/alcohol mixtures used in aircraft and automotive engines. The lithium salts, which may be added to clear fuels or fuels containing up to 6.0 ml. of tetraethyllead per U.S. gallon, are used in amounts corresponding to 0.01 gram to 2.0 grams of lithium metal per U.S. gallon. They may be used in conjunction with conventional fuel additives such as scavenging agents, dyes, antioxidants &c. Their solubility in the fuel is enhanced by the use of blending agents such as alcohols, glycols, esters, ketones, and amides. In examples specified blending agents are ethanol and isopropanol. Specification 668,341 is referred to.