GB716009A - Improvements in or relating to aviation fuel - Google Patents

Abstract

An aviation gasoline comprises not more than 10 per cent. by volume of C4-C8 branched chain alkyl ethers and not more than 22 per cent. by volume of C7-C10 aromatic hydrocarbons, there being 0.5.2-5 volumes of the aromatic hydrocarbons to each volume of the ethers. Branched chain alkyl ethers mentioned are di-isopropyl ether, methyl tertiary butyl ether and ethyl tertiary butyl ethel. C7-C10 aromatic hydrocarbons mentioned are o-, m- and p -xylene, ethyl benzene, n- and iso-propyl benzene, o-, m-and p-ethyl toluene, pseudocumene, mesitylene, toluene, hemimellitene, sec-butyl benzene and triethyl benzene. The gasolene may comprise paraffins, isoparaffins, and naphthenes and, in particular, alkylate (prepared by the alkylation of isobutane with butenes and/or pentenes), virgin naphtha and isopentane. The gasoline may also contain oxidation and corrosion dyes and tetraethyl lead. A preferred composition (in which the percentages are by volume) is di-isopropyl ether 5 per cent.; butenes alkylate 45.6 per cent.; virgin naphtha 25.8 per cent.; xylene 5.4 per cent.; toluene 5.4 per cent.; and isopentane 12.8 per cent. To this composition there may be added tetraethyl lead, 2, 6-di-tert.-butyl-p-cresol and red dye. Small amounts of water, which have become dissolved in the aviation gasolines of the invention, separate as ice only at extremely low temperatures. Tests are described in which (1) alkylate containing methyl tertiary butyl ether or ethyl tertiary butyl ether, with or without toluene, is saturated with water and cooled until a solid phase separates, (2) butenes alkylate containing toluene, xylenes, ethyl benzene, isopropyl benzone, trimethyl benzenes, sec.-butyl benzene or triethyl benzene is saturated with water, cooled to -50 DEG F. and the time taken for the composition to plug a 10 micron filter measured and (3) butenes alkylate containing virgin naphtha and di-isopropyl ether, with or without mixed C7 and C8 aromatic hydrocarbons, is saturated with water, cooled to -20 DEG F. and the time taken for the composition to plug a 10 micron filter is measured.