GB742912A - Improvements relating to catalytical removal of free oxygen from gases containing free hydrogen and hydrogen sulphide - Google Patents

Abstract

In a process for removing, by means of a catalyst accelerating the reaction of oxygen with hydrogen, free oxygen from a gas, e.g. shale distillation gas, containing free hydrogen and hydrogen sulphide in addition to oxygen in a concentration greater <PICT:0742912/III/1> than the critical concentration for the catalyst, i.e. that concentration of oxygen at which the amount of sulphur formed per unit of time by the oxidation of hydrogen sulphide with oxygen is equal to the amount of sulphur removed by evaporation and by reduction with hydrogen, the gas is diluted with a quantity of a gas of little or no oxygen content such that the oxygen concentration of the gas mixture will be below the critical concentration and the gas mixture is passed over the catalyst at a temperature between 150 DEG and 350 DEG C. Suitable gases for the dilution are steam, natural gas, gas obtained by cracking mineral oil or mixtures thereof or gas freed from oxygen in the process. The catalyst mass comprises a catalyst component containing at least one of the metals molybdenum and tungsten as a sulphide and/or oxide, a promoter component containing at least one of the metals iron, cobalt, nickel, chromium, vanadium and uranium in the form of a sulphide and/or oxide, and a carrier component based on alumina, silica gel, magnesium oxide, aluminium silicate or mixtures thereof. The atomic ratio between the metals in the catalyst and promoter components and the positive element of the carrier component should be 1-10 : 1-10 : 10-100, being preferably within the limits 0.5-1.5 : 0.5-1.5 : 10 and the amounts of catalyst and promoter components being of the same order. In one embodiment for treating a gas containing about 2 per cent oxygen four reactors R1, R2, R3 and R4 are employed. Preheated untreated gas is introduced by line 1 into the reactors by lines 2, 7, 9 and 11, 7 per cent, 14 per cent, 28 per cent and 51 per cent of the untreated gas being fed respectively into reactors R1, R2, R3 and R4. Treated gas is recycled from reactor R4 by line 3 into reactor R1 and in a quantity equal to 7 per cent of the untreated gas. The gases from reactor R1 pass by line 6 into reactor R2, the gases from reactor R2 pass by line 8 into reactor R3 and the gases from reactor R3 pass by line 10 into reactor R4. Some of the untreated gas introduced into each reactor may be unpreheated, the proportion for a particular reactor being chosen to obtain the desired temperature in the reactor. Some of the oxygen free gas introduced by line 3 into reactor R1 may be replaced by another gas of low oxygen content introduced through line 5. In a modification the four reactors are arranged one above the other in a vertical column. Specification 719,791 is referred to.