DE2457909A1 - METHOD FOR THE SELECTIVE REMOVAL OF HYDROGEN SULFUR FROM HOT GASES - Google Patents

Description

PATENT ADVERTISER D-1 BERLIN 33 December 3, 1974

MANFREDMIEHE FALKENRIED 4

Telephone: (030) 8 3119 50;

Chemist Telegrams: Indusprop Berlin

Telex: 0185443

US / 52/2199 FD 3985

FOSTER WHEELER CORPORATION 110 South Orange Avenue, Livingston, New Jersey ' UNITED STATES

Process for the selective removal of hydrogen sulfide from

hot gases

It becomes a continuous process for the selective removal of hydrogen sulfide from a mixture created hot gases containing hydrogen sulfide by such a mixture in a reaction or a desulfurization zone in contact with a nickel-containing material at an elevated temperature is brought, wherein the nickel with the hydrogen sulfide to form solid bonds converts, from which the nickel content is regenerated by means of oxidation and returned to the reaction zone can be and thereby in an effective manner hydrogen sulfide from the hot gas mixture removed. .

Since the relevant regulations on air pollution came into effect it has become necessary to remove sulfur-containing gaseous pollutants from exhaust gases, some of which, e.g. SO2, have so far been released into the atmosphere. More sulfur containing gaseous pollutants, such as hydrogen sulfide and other sulfides, such as CS2, the more common heretofore Manner in exhaust gases, e.g. those that resulted from coal or oil gasification, had to be removed as well, and not just because of the resulting corrosion

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sion problems, but also because those during the combustion sulfur oxides formed would be a nuisance for fuel gas consumers.

So far, hot gas mixtures containing H2S are due to the coal or oil gasification resulting, has been purified by the fact that their H2S content by means of conventional washing removed, which can be wet or dry washing such as alkali washing. The dry washing process, which has now been largely displaced by the wet process, consisted in the removal of sulphides, such as H2S, by means of contact with dry iron oxide or hydroxide and then extracting the spent hydroxide and reactivating it the same using carbon disulfide for the purpose of recovering the sulfur. On the other hand, wet washing has essential simplifies the entire process of fuel gas cleaning, whereby washing of the fuel gas is carried out with various liquids, for example an alkali solution such as a dilute 3% Sodium carbonate solution. For other wet processes, diluted, 1-2% sodium carbonate solutions with iron (III) hydroxide suspended in them, aqueous arsenic oxide solution in sodium carbonate, cold solutions of organic amines, such as a 50% aqueous solution of Diethanolamine; Sodium phenolate in the form of a fairly concentrated one Solution of phenol in sodium hydroxide; etc. have been applied. The wet washing, however, has not been found to be entirely satisfactory proven, since there is often a need for expensive special equipment, such as absorbers, e.g. working with a bell jar or packed absorption towers, heat exchangers and the like. A major advantage of the subject matter of the invention is its ability to purify the fuel gas by means of removal the H2S in a much simpler way than this has been done by the various previously used washing processes was possible. Thus, according to the invention, the H2S contamination of fuel gases can easily be eliminated by the fact that at increased

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th temperatures a nickel catalyst is used, whereby the Requirement for expensive heat exchange equipment in Eliminate, which was required in the prior art along with the washing process, and this catalyst can easily regenerate through oxidation, e.g. air oxidation.

The invention relates to a method for the selective removal of hydrogen sulfide from a mixture of hydrogen sulfide containing hot gases and in particular a method for selective removal of hydrogen sulfide from a mixture of H2S containing hot gases, such as those resulting from coal gasification Exhaust gases by reacting such a mixture with a nickel-containing material, the nickel with the hydrogen sulfide to form solid compounds converts, from which the nickel content by means of oxidation and recycling of the nickel in the reaction zone for the purpose of further Recovered reaction with more hot gas mixture containing H2S can be.

According to a preferred embodiment of the invention, a suitable exhaust gas, such as the usual gas coming from a conventional oil or coal gasifier, over a nickel catalyst at increased Temperature performed in a suitable reaction vessel or reaction zone. The gaseous fuel usually represents represent a mixture containing hydrogen and carbon monoxide in a ratio of 0.7 to 1.3 volumes of hydrogen per volume of carbon monoxide contains, and also has a small amount of carbon dioxide, water vapor, methane and hydrogen sulfide, wherein the sulfur content is about 0.3 to 6.0%.

The nickel catalyst preferably contains: metal, metal alloy, such as nickel-aluminum or another nickel-containing material, or the oxides thereof. Such a catalyst can naturally

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also loaned an inert carrier to any of the usual ones standing species are borne. Corresponding examples of carrier materials that can be used as solid carrier components of the catalyst can be used, the various aluminum- and silicon-containing materials are natural or of synthetic origin, such as bauxite, aluminum oxide, activated clay, Kieseiguhr, clay gel, silica gel, magnesium oxide gel, mixed gels, magnesium oxide, magnesium silicate, pumice stone, kaolin, clays, carborundum, alundum etc. One of the support materials given here, for example, is activated carbon. The catalyst is preferably nickel or one containing nickel Material.

The gaseous exhaust stream is preferably passed through a bed of the nickel catalyst at a temperature of about 250 to about 1000 C, and preferably from about 350 to about 600 ⁰ C. The exhaust gas is fed into the reaction zone at a temperature close to the desulfurization temperature, thereby maintaining the reaction zone in thermal equilibrium. As soon as the nickel content of the catalyst is depleted by the fact that it has been converted into solid nickel sulfide compounds, these latter compounds are withdrawn from the bed and replaced by regenerated nickel catalyst which is continuously fed to the bed. The spent catalyst solids are transferred to a regeneration zone where they are subjected to controlled oxidation with an oxygen-containing gas, such as air.

According to a preferred embodiment, the spent catalyst regenerated by venting, i.e. by blowing air through the spent catalyst bed. By means of setting the The rate at which the fuel gases are introduced into the reaction vessel or desulfurization or reaction zone, im Relationship to the characteristics of the catalyst solids,

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nen the latter in the form of a fluidized bed or im suspended state in the gases during the treatment period. Regeneration of the catalyst is preferred carried out at a sufficiently high temperature that corresponds to the equilibrium conditions required for both the Regeneration reaction as well as the reaction between Ni and SO2 are decisive.

Since the hydrogen content of the exiting gas is high, is it prefers the treatment of this gas with the nickel catalyst at temperatures at the lower. End of the above Temperature range from 430 to 950 C, preferably from about 480 to about 76O ° C to carry out so as to the slope of the To counteract the formation of hydrogen H2S.

The spent catalyst consisting of solid compounds of nickel sulfide can, after being separated from the fuel gas exhaust gas, be regenerated in a separate regeneration zone in which the NiS compounds can be reacted directly with oxygen from the air by means of ventilation, the air through the spent catalyst is blown at temperatures approaching those in the reaction zone. In the regeneration zone, the solid NiS compounds are reacted with the oxygen in the air to form sulfur dioxide and the free catalyst and are then separated, the catalyst solids being returned to the reaction zone for further contact with the H ₂ S, which is present in the newly introduced exhaust gas.

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Claims (5)

Claims 1. A method for the selective removal of hydrogen sulfide from hot gases, characterized in that a Exhaust gas containing hydrogen sulfide in a reaction zone, which contains a solid nickel material, is brought into contact at an elevated temperature, the nickel material at least is partially sulfided, then the sulfided nickel material is withdrawn from the reaction zone and into a regeneration zone is transferred, as well as the sulfided. Nickel material subjected to the action of an oxygen source at an elevated temperature is, whereby sulfur dioxide and a regenerated nickel material come to the formation. 2. The method according to claim 1, characterized in that that the same is carried out continuously and nickel is used as a solid nickel material, which regenerates Nickel catalyst is returned to the reaction zone. 3. The method according to claim 2, characterized in that that the regenerated nickel catalyst is continuously returned to the reaction zone while maintaining a Nickel and nickel sulfide composition in the same, which for a constant rate of sulfur removal from the exhaust gas in the Reaction zone is kept constant. 4. The method according to claim 2, characterized in that that the exhaust gas enters the reaction zone at a temperature is introduced adjacent to the desulfurization temperature while maintaining the reaction zone in thermal equilibrium. 5. The method according to claim 2, characterized in that that the regeneration of the nickel catalyst is carried out at a temperature sufficient to maintain the equilibrium conditions which determine both the regeneration reaction and the reaction between Ni and SO2. 5 0 9829/0554