| 摘要 |
1370953 Purifying gases INSTITUT FRANCAIS DU PETROLE DES CARBURANTS ET LUBRIFIANTS 31 Jan 1972 [29 Jan 1971] 4491/72 Heading C1A Gases containing as impurities COS and/or CS2 are purified by a process wherein (a) an impure mixture containing CS2 and/or COS together with steam is contacted in a first reaction zone with an alumina-containing catalyst at 250-400‹ C., which converts COS and CS2 to H2S, (b) the resulting mixture is reacted in a second reaction zone with O2 at 300-500‹ C. to bring the molar ratio H2S/SO2 in the mixture to a value between 1À6 and 3 (by oxidation of some of the H2S to SO2), and (c) the resulting mixture is contacted in a third reaction zone at 20-160‹ C. with an organic solvent inert with respect to the gas to be purified, to produce sulphur by interaction of SO2 and H2S contained in the mixture. The process is applicable to gas effluents, e.g. from a Claus unit, comprising 0À01-4% by volume of sulphur compounds (COS and/or CS2 and sometimes additionally H2S and SO2), 5-60% steam, small amounts of H2 and the balance comprising N2 and CO2. The Claus unit effluent may be previously washed with an organic solvent. The alumina catalyst used in step (a) preferably has an alkali metal content below 0À1% and may contain one or metals from Groups VIA and VIII preferably as the sulphide. Oxidation step (b) may be effected in the presence of an oxidation catalyst for example alumina containing one or more oxides of metals from Group VA, VIA or VIII. The solvent used in step (c) may be a glycol or polyglycol or ether and/or ester thereof, a tri-ester of phosphoric acid, a higher alcohol or sulpholane and the solvent preferably contains a catalyst for the SO2-H2S interaction, e.g. salts of'metals of Groups IA and IIA with carboxylic acids or partial esters of polycarboxylic acids (see for example Specification No. 1,331,540) ammonia, amines, alkali and alkaline earth metal hydroxides and alkali metal salts of weak inorganic acids. Examples illustrate the purification of Claus effluents (1) as above and (2) using only step (a) and/or (c), or steps (a), (b) and (c) with an H2S/SO2 ratio in (b) of 1À5. |
