GB409901A - Improvements in or relating to the refining of hydrocarbon oil distillates - Google Patents

Abstract

Hydrocarbons especially cracked distillates are freed from colour, gum-forming and sulphur compounds by treating in the liquid phase under elevated temperature and pressure with hydrochloric acid and a metal or metal compound as catalyst. Metals and metal compounds specified are:--iron, nickel, cobalt, zinc, copper, tin, aluminium or mechanical mixtures or alloys such as brass or bronze, ores of zinc, copper, tin, iron or lead such as Willemite, Calamine or Troostite (zinc silicates), Smithsonite (zinc carbonate), or aurichalcite (hydrated carbonate <PICT:0409901/III/1> of zinc and copper). The gangue present in such minerals may be removed by flotation, electrical separation &c. or may be retained as an inert spacing material. Cracked gasoline passes through a pipe coil 6 mounted in a furnace 7 and the oil emerges at a temperature of 260--345 DEG C. and under a pressure of 27--34 atmospheres through a pipe 8 where it is mixed with a small amount of 20 per cent hydrochloric acid admitted from a pipe 19. The mixture enters the treating tower 12 containing brass turnings or a mixture of iron and copper oxides deposited on an inert adsorbent such as crushed firebrick, pumice, sand, clay, fuller's earth or diatomaceous earth. The mixture rises through the tower and passes to a fractionator 23 which is maintained at a lower pressure of from 3 to 7 atmospheres. Heavy flux oils are removed through a valve 25 and the vapours pass through a condenser 28 to a receiver 31. Finished gasoline is drawn off through a pipe 34 aqueous deposits through a pipe 36 and gases through a pipe 32. In the case of oils of high sulphur content, a series of treating towers may be used, and the sulphuretted hydrogen formed is vented at each stage whereby the formation of metal sulphides and mercaptans is prevented. The vented gases may be passed through a bed of granulated metal and the chlorides and sulphides recovered. Hydrochloric acid may be supplied as an aqueous solution, or hydrochloric acid gas and water or steam may be admitted separately.