GB744159A - Improvements in the desulphurisation of crude petroleum oils and their residues - Google Patents

Abstract

Crude petroleum oils or their residues are desulphurized by passing them, together with hydrogen, first over large-surfaced material at a temperature of 300 DEG -500 DEG C. and under increased pressure, and then over one or more synthetically-prepared silicates of metals of the 8th group of the periodic system at raised temperature and under increased pressure. The hydrogen may be employed as such or in the form of a hydrogen-containing gas such as illuminating gas, water gas, cracking gas, coke oven gas or low temperature carbonization gas. The large-surfaced materials either have a great porosity or have a special large-surfaced shape, as in the case of rings, hemispheres, or angular structures such as cubes, cones, truncated cones or pyramids which are open on at least one side and which may contain partitions in the hollow spaces. The large-surfaced materials may consist of ceramic materials, such as porcelain or clay, metals such as steel, pumice, bleaching earths or synthetic silicates. The Group VIII silicate employed in the second stage may be a silicate of iron, nickel, cobalt platinum or ruthenium and contains 0 to about 8 per cent of aluminium and magnesium. A compound, preferably an oxide, of a Group VI metal such as molybdenum or tungsten, may be incorporated with this silicate catalyst. In the first stage, organic ash-producing constituents of the feed oil are decomposed with deposition of the ash, thereby allowing the reduction of sulphur compounds to hydrogen sulphide in the second stage to be carried out for long periods without regeneration of the silicate catalyst. The ash separated in the first stage may be removed by blowing it out, or running it off or by sifting the large-surfaced material, while the silicate catalyst employed in the second stage may be regenerated, when necessary, with the aid of oxygen-containing gases. In the example, crude petroleum, together with hydrogen, at 395 DEG C. and a pressure of 50 atmospheres, is led through a vessel packed with clay Raschig rings. The effluent oil and hydrogen is passed through a preheater and then over a catalyst consisting of molybdenum trioxide on nickel silicate, the preheater being so adjusted that the temperature of this catalyst is initially 365 DEG C. but rises gradually to about 440 DEG C. Preparation of catalysts. The Group VIII metal silicate catalyst may be prepared by mixing a waterglass solution with a solution of a compound of a Group VIII metal and then (a) adjusting the pH of the mixture to a value between 2 and 7 by the addition of acid and then standing, (b) adding a precipitant such as ammonia or an ammonium compound, for example ammonium carbonate or sulphate or by dropping the mixture at a pH of about 5-9 into an oil such as a gas oil fraction so that a catalyst in the form of pellets is produced. In the example, nickel carbonate is dissolved in aqueous sulphuric acid and the solution mixed with waterglass solution. The mixture is brought to a pH of 9-10 by addition of sodium carbonate solution and the precipitate which separates is washed, dried, pelleted and heated above 400 DEG C. It is then impregnated with ammonium molybdate solution and again heated above 400 DEG C., so that the final catalyst contains molybdenum trioxide.