Chemistry of inorganic compounds – Sulfur or compound thereof – Elemental sulfur
Patent
1997-01-22
2000-05-02
Griffin, Steven P.
Chemistry of inorganic compounds
Sulfur or compound thereof
Elemental sulfur
423222, 423230, 42324409, 4232441, 502178, 502302, 502303, 502305, 502325, 502340, 502349, 502354, 502344, B01D 5350, B01D 5352, B01J 2300, C01B 1704
Patent
active
060569360
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for catalytic desulphurization of a gas containing the sulphur compounds H.sub.2 S and SO.sub.2 and possibly COS and/or CS.sub.2, with recovery of the said compounds in the form of sulphur. It further relates to a catalyst for using this process.
It is known that H.sub.2 S reacts with SO.sub.2 in the presence of catalysts, based, for example, on one or several metal oxides such as alumina or titanium oxide, to form sulphur according to the Claus reaction which is written:
Many processes for desulphurization of gases containing H.sub.2 S and SO.sub.2 use the Claus reaction in contact with a catalyst with a view to the recovery of the said compounds H.sub.2 S and SO.sub.2 in the form of sulphur.
In such processes the gas to be desulphurized, containing H.sub.2 S and SO.sub.2, is passed in contact with a catalyst which promotes the Claus reaction given above, this contact being produced at temperatures which are either higher than the dew point of the sulphur formed in the reaction gases, in which case the sulphur formed is present in the form of vapour in the reaction mixture originating from the reaction, or else at temperatures which are lower than the dew point of the sulphur formed, in which case the said sulphur is deposited on the catalyst, which makes it necessary to regenerate the sulphur-laden catalyst at regular intervals by purging with a nonoxidizing gas which is at a temperature of between 200.degree. C. and 500.degree. C.
In particular, the reaction between H.sub.2 S and SO.sub.2 at temperatures which are higher than the dew point of sulphur, that is to say at temperatures higher than approximately 180.degree. C., can be carried out in contact with a catalyst consisting of alumina or bauxite (U.S. Pat. No. 2,403,451), of alumina associated with a zinc, cadmium, calcium or magnesium compound (FR-A-2126257), of activated alumina associated with a cobalt, nickel, iron or uranium oxide or sulphide compound (FR-A-2190517), of alumina associated with a titanium compound (FR-A-2224203), of alumina associated with a compound of yttrium, of lanthanum or of an element of the lanthanide series with atomic numbers ranging from 58 to 71 (FR-A-2242144), of titanium oxide (FR-A-2481145), or else of titanium oxide associated with an alkaline-earth metal sulphate (EP-A-0060741). The catalysts described in citations FR-A-2126257, FR-A-2190517, FR-A-224203, FR-A-2481145 and EP-A-0060741 are very particularly advantageous when the gas to be treated also contains organic sulphur compounds such as COS and/or CS.sub.2, in addition to the sulphur compounds H.sub.2 S and SO.sub.2.
The reaction between H.sub.2 S and SO.sub.2 carried out at temperatures such that the sulphur formed is deposited on the catalyst can be performed, for its part, in contact with a catalyst consisting, for example, of activated alumina, silica, a mixture of silica and alumina or else a natural or synthetic zeolite (FR-A-2180473 and FR-A-2224196), of alumina associated with an iron, nickel, cobalt, copper or zinc compound (FR-A-2327960), of alumina associated with a compound of titanium, yttrium, lanthanum or lanthanide of atomic number ranging from 58 to 71 (WO-A-9112201), of titanium oxide associated with a nickel, iron or cobalt compound (EP-A-0215317 and EP-A-0218302) or else of active carbon (FR-A-1603452).
Catalysts such as the abovementioned, which are employed to promote the sulphur-forming Claus reaction between H.sub.2 S and SO.sub.2 and optionally the hydrolysis of the compounds COS and CS.sub.2 to H.sub.2 S, still present some inadequacies in extended use.
Under the combined effect of temperature and of the presence of water the catalysts based on alumina, silica, titanium oxide or active carbon undergo, in time, transformations which are reflected in a decrease in the specific surface and in the porosity of the said catalysts and which result in a loss of their catalytic activity. In addition, alumina-based catalysts are liable to change in time owing to sulphate formation, and this is an addition
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Copies of the English Translations for WO 91/12201 A1
and EP 0 422 999 A1.
Nougayrede Jean
Philippe Andre
Elf Exploration Production
Griffin Steven P.
Vanoy Timothy C
Weiser Gerard J.
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