GB692488A - Improvements in or relating to the refining of petroleum oils - Google Patents

Abstract

Finely divided metallic lithium, sodium or potassium is contacted with petroleum oil in the presence of an activator comprising an ether, a ketone or an alcohol, and the treated oil is filtered at a temperature below about 50 DEG C. The treatment removes gum-forming substances, improves the colour and sweetens the oils. The process is applicable to gasolines, heating oils, Diesel fuels and to petroleum oils in general, but in particular to thermally or catalytically cracked gasolines. Sodium is the preferred alkali metal, and it may be used in the form of particles of size less than 50 microns in diameter or smaller (30 or even 2-10 microns). It may be used in suspension in a high-boiling hydrocarbon oil free from olefines such as a virgin naphtha of B.P. 300-400 DEG F. Dispersing agents such as sodium oleate or a resinous polymer may be added to maintain the suspension. The preferred ethers are secondary aliphatic ethers containing 4-10 carbon atoms such as isopropyl ether or secondary butyl ether, but other ethers such as ethyl ether, normal propyl ether, isobutyl ether, benzyl ether and mixed ethers may also be used. Acetone is the preferred ketone, but methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone may also be used. The alcohols may be monohydric or polyhydric, the secondary and tertiary monohydric alcohols being preferred, and it is desirable that they should contain less than seven carbon atoms per molecule. The time of treatment may be from 10 minutes to 2 hours. The temperature may be above 40 DEG C and preferably from 200-250 DEG C. When using a secondary or tertiary alcohol as activator, the preferred temperature range is from 70 DEG -250 DEG C, with ketones from 200-225 DEG C and with ethers from 200-250 DEG C. The concentration of sodium is from 0.25-2.0 per cent (preferably 0.5 to 1.0 per cent) by weight, based on the oil to be treated. Its concentration in the vehicle may be 50 per cent by weight or higher. The quantity of activator may be 5-30 molar per cent (preferably 5-10 molar per cent) based on the weight of sodium used. After filtration, oils containing acid materials may be washed with water or an acid wash to remove oil soluble sodium salts. In the examples there are reported the results of tests carried out on thermally cracked and catalytically cracked naphthas, crude gasoline, and thermally cracked gasoline purified according to the process of the invention using finely divided metal sodium and various activators.