GB669981A - Bleaching process for mineral oils and paraffins - Google Patents

Abstract

A process for decolourising mineral oils for medicinal use by treatment in the liquid phase with hydrogen under conditions of high temperature and pressure and in the presence of a hydrogenation catalyst is characterised in that the oil, without preliminary treatment for removal of constituents inimical to the catalyst, is submitted to hydrogenation in the presence of a non-activated catalyst consisting of a metal of the 8th group or an oxide thereof, alone or in the presence of alumina, under a pressure of between 200 and 300 atmospheres and at a temperature between 80 and 450 DEG C., the conditions being such as to avoid appreciable decomposition of the oil. The hydrogenation may be followed by a refining treatment with sulphuric acid, oleum, bleaching earth or activated carbon. In an example, a white technical oil was produced from an unrefined distillate of the spindle oil type by forcing it through a continuous hydrogenation plant at the rate of 1 kg. per hour per litre of reaction chamber under 250 atmospheres at 350 DEG C. with 2 cub. metres of hydrogen per kg. of oil charged and in the presence of 3 per cent (by weight of oil charged) of a mixture of iron and aluminium oxides. The product was again hydrogenated under similar conditions but using a catalyst of freshly-reduced nickel oxide, giving a yield of 95 per cent of a colourless oil. In another example the final hydrogenation product was treated with 2 per cent of 98 per cent sulphuric acid followed by two further treatments with 5 per cent of oleum and then with bleaching earth yielding a 70 per cent yield of a white odourless and tasteless oil.