CA1125731A - Process for the catalytic incineration of hydrogen sulphide-containing waste gases and a catalyst composition therefor - Google Patents
Process for the catalytic incineration of hydrogen sulphide-containing waste gases and a catalyst composition thereforInfo
- Publication number
- CA1125731A CA1125731A CA294,517A CA294517A CA1125731A CA 1125731 A CA1125731 A CA 1125731A CA 294517 A CA294517 A CA 294517A CA 1125731 A CA1125731 A CA 1125731A
- Authority
- CA
- Canada
- Prior art keywords
- weight
- catalyst
- copper
- bismuth
- hydrogen sulphide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/843—Arsenic, antimony or bismuth
- B01J23/8437—Bismuth
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/52—Hydrogen sulfide
Abstract
ABSTRACT OF THE DISCLOSURE
A process for reducing the total sulphur content of Claus process off-gas is described. The reduction is achieved by using in the oxydation step a catalyst comprising 0.6% to 10 by weight bismuth, and 0.5 to 5% by weight copper, based on the total weight of the catalyst in which catalyst the weight percent-age of bismuth exceeds the weight percentage of copper. Conveni-ently the catalyst is used on a support, such as alumina or silica.
A process for reducing the total sulphur content of Claus process off-gas is described. The reduction is achieved by using in the oxydation step a catalyst comprising 0.6% to 10 by weight bismuth, and 0.5 to 5% by weight copper, based on the total weight of the catalyst in which catalyst the weight percent-age of bismuth exceeds the weight percentage of copper. Conveni-ently the catalyst is used on a support, such as alumina or silica.
Description
llfA,'5 7ff~
L~ L` f ` .l ~lt;.~ o ~ :L' O C f ~ ., .[ ( ) f" t, lf l f ` ' ~ t~llJ~
i~C.i~ iiOII o.L` hydrogcn u:lp~-l;d~-contain:in~ wast- frascs i~ cont~cii.nf, s~.i.d wastl^ ga.;es wi.~h a scoichiometr c excess o 1' OXygf n Wi tn recpect to the containf_d hydrogen sulphide in the presence of a catalyst. It also relates to a eatalyst comp.)si.tion which can suitabl.y be applifd in such a process.
Viewed i.n the light of increasingly stringent re-quirements with respect to air pollution abateme.nt, various procedures have been developed to remove hydrogen sulphide (H2S) from proeess off-gases, and even reeover, if possible, H2S or reaetion products of H2S contained therein. For example, the well-known Claus process produees an effluent normally eontaining up to 2% or even 3% by weight sulphur eompounds, a substantial proportion thereof being H2S.
To remove this eoneentration of sulphur eompounds, seleetive absorption by eontaeting the Claus off-gases with a suitable absorption solvent, after a hydrogen-ation treatment of the off-gases, has been practised.
In this proeedure, the bulk of the desorbed H2S after regeneration of the absorption solvent, is returned to the Claus unit, and the final off-gas or tail gas, eontaining nitrogen, C02 and quite minor amounts of H2S is incinerated. During incineration, H2S is con-ver~ced to sulphur dioxide (S02), a material which ~1~S731 as rig;~d ;lS those apr)l-ic(l to ll2~. IIowcver, ;ncirIcratic)n is costly because of the necQssary heat input. Again, al.houg'l some work has been done with regard to catalytic conversion of H2S in the off-gas or tail gas to S02, concomi-tant formation of sulphur trioxide (S03) has been a problem.
A process is known for the purification of gases contaminated with hydrogen sulphide by oxidizing said hydrogen sulphide in the presence of catalysts which contain as the main constituents metals, such as niekel, iron, cobalt, manganese, zine and eopper, or their eompounds, either alone or together with metals or metalloids of Groups 4, 5 and 6 of the Periodie System of Elements and in addition thereto, small quantities of an aetivating material, such as lead or bismuth or their compounds, or alkali metal or alkaline earth metal compounds. The amount of the aetivating material employed is up to about 10%, based on the weight of the total amount of metals present.
Said known eatalysts have a disadvantage in that their aetivity deereases rapidly~ requiring a temperature raise of about 5C every three days. Moreover, about 10~ of the hydrogen sulphide present is eonvertc-d to S03~ whieh is a highly objectionable compound from an air pollution-abatement point of view.
~1~25731 Accoriingly, there still exists a need for an economical method for the purificatioll of i-12S-containing streams, particularly off-gas streams of the type mentioncd, which method would provide substantial conversion of the H~S values in the off-gas, and concomitantly provide low SO3 emissions.
The method should be economical in that the necessary heat input should be as low as possible as evidenced by relatively low process temperatures.
~breover, the catalysts to be applied should show an activity which remains constant over a long period.
The present invention has as its object to satisfy that need.
The present invention accordingly relates to a process for the catalytic incineration of hydrogen sulphide-containing waste gases by con-tacting said waste gases with a stoichiometric excess of oxygen with respect to the contained hydrogen sulphide in the presence of a catalyst in which process the hydrogen sulphide-containing waste gases are contacted with oxygen at a temperature in the range of from 150 to 450C in the presence of a catalyst comprising as the catalytically active components bismuth in an amount of from 0.6 to 10% by weight and copper in an amount of from 0.5 to 5% by weight, based on the total weight of the catalyst.
~1~57;~1 Z -i slZ~ r~ ~ ~)( rl ~:c,~ cl tilat ~ o r a catalyst contain;n~r both bismuth (Bi) anc1 copper (Cu), in spt?cifit-d proportions and amounts, givr-s resultc not att?illablt? by use of comparable arnounts of Cu or Bi alone. The une~pected aspect of the process of the invent:ion resides in the ability to utiliz? temper-atures of reaction not attainable, on a weight basis, with catalysts of Cu or Bi alone. Additionally, any combustibles, e.g., H2, C0, CH4, present in the streams to be treated appear unaffected or substantially unaffected by the catalyst of the invention. The S02 r^ormed may be vented or recovered in a manner known to those skilled in the art.
Although the invention is apparently applicable to any H2S-containing stream of low to moderate H2S
concentration, the invention is ideally suited to the treatment of H2S-containing off-gases fronZ various processes from which no further or little recovery of other materials is made. The invention is eminently suited, as indicated, to the treatment of the effluent from a Claus plant. The Claus process is normally itself a "clean-up" process, wherein elemental sulphur is prepared by partial oxidation of H2S, using an oxygen-containing gas (including pure oxygen) to form S02, followed by the reaction of S02 produced with the remaining part of the H2S, in the presence of a catalyst.
11~5731 i'`l~` `~)I~C `.: iS fI~ IIen'C~.y used clt rei irleri . ~ind al; o ior t;~-1e ioric-ul) oi`ll2S recovered from various gas Stl'eamS, such as natural gas. Since the yield of elem-ental sulpl1ur, relative to the hydrogen sulphide introduced, is not quantitative, a minor amount of unreacted H2S, COS, CS2, and S02 remains in the Claus off-gases. To some extent, the amount of elemental sulp}1ur recovered depends on the number of catalyst beds employed in the Claus process. In lQ principle, about ~% of the total sulphur available can be recovered when three catalyst beds are used.
The invention is eminently suited to the removal of H2S from Claus plant effluents.
Additionally, as indicated, Claus plant effluents or Claus off-gases may previously have been processed by a Claus tail gas treating process. Such a process may comprise the steps of reducing S02, COS, CS2, and S03 contained in the gas under suitable conditions to H2S in the presence of a catalyst, absorbing the H2S, followed by desorption of the H2S and recycle of the desorbed H2S to the Claus plant. Where this procedure is practised, the invention provides for the oxidation of the quite miinor or reduced ~mounts of H2S, and the like, remaining -in the final off-gas by contacting said off-gas with oxygen under the conditions indicated.
~125731 'ih~ talyst e~ loycd :in tl,c pro~es. jf th~ :in-v lltiOIl ~ )c a sol;cl mattrial containing copper alld bismutrl as the catalytically active components.
The particular form ~.Aiherein the catalytically acti-~e components are present in the catalyst, i.e., whether as compounds or the elements or compounds combined in a carrier material, does not appear to be critical.
Where a carrier is employed, the only apparent re-quirement concerning the sources of the copper and bismuth is that the copper and bismuth be in a form adapted to solution, either as an ordinary solution (both aqueous and organic solvents) or as a solution of a liquid or complex of copper or bismuth. Certain salts and the oxide and hydroxide of copper and bismuth may change cduring the preparation of the catalyst, during heating in a reactor prior to use in the process of -this invention, or may be converted to another form under the described reaction conditions, but such materials still function as effective catalysts in the defined process. For example, the nitrates, nitrites, carbonates, hydroxides, citrates and acetates may be converted to the corresponding oxide and then to the sulphide under the reaction conditions defined herein. Such salts as the phosphate, sulphate, halides, and the li~e, which are stable or partially stable at the defined reaction temperature, are 1~573~
similarly effective under the conditions of the described reaction, as well as such compounds which are converted to another stable form in the reactor.
Copper nitrate and bismuth nitrate are, however, preferred materials, since they are inexpensive and are readily soluble in water and can easily be deposited on carriers. The catalysts of this invention are solid at room temperature or are essentially solid under the conditions of reaction (although some volatilization may occur).
To achieve meaningful lowering of the reaction temperature with concomitant COS conversion the presence of minimum amounts of Cu and Bi is essential. In general, concentrations of at least 0.5% Cu and 0.6% Bi (all by weight) are required in the reaction zone, with concentrations of at least 0.8% Bi being preferred. Dramatic improvement over the Cu and Bi alone occurs when the concentration of Cu is at least about 1.0% and the con-centration of Bi is at least about 2.0% (all by weight). Where a carrier is employed, for example, the Cu will normally be present in an amount of up to about 5% by weight, based on the total weight of the catalyst material.
Preferably, the amount of Cu will not exceed about 3% by weight and the amount of Bi, preferably, does not exceed 5% by weight. It is preferred, however, that the amount of bismuth 112573~
p~.ent in th~` c;.t,alyst; :iS a]W~ly.. 'UlCIl t,h'lt, t,l-l''`
ce t;;',l~''it COIIlpI'i '>~`S cl major amc~urlt of bismllth and a IllillOr ;lr.lOUnt of copper.
If solid compouncls of Cu and Bi are employed, or if heavy concentrations of Cu and Bi on a carrier are employed, the catalytically active materials will normally be diluted with inert rnaterials so that activity may be regulated. Proper dilution to the concentrations specified is within the skill of the art, and need not be detailed herein.
Excellent results have been obtained by packing the reactor with the defined catalyst particles as the method of introducing the catalytic surface. The size of the catalyst particles may vary widely, but generally the maximum particle size will at least pass through a Tyler standard screen which has an opening of 2 inches, and the largest particles of catalyst will pass through a Tyler screen with one inch openings. Very small particle size carriers may be utilized, the only practical objection being that extremely small particles cause excessive pressure drops across the reactor. In order to avoid high pressure drops across the reactor, at least 50% by weight of the catalyst should be retained by a 4 to 5 rnesh Tyler standard screen. However, if a fluid bed reactor is utilized, catalyst particles may be quite small, such as from about 10 to 300 microns. Those skilled in the art can readily determine appropriate particle slze depending on reactor configuration and size, and gas velocity to be applied.
If a carrier is used, the catalytically active compon-ents may be deposited on the carrier by methods known in the art, such as by preparing in aqueous solution or dispersion of the des-cribed catalyst, and mixing the carrier particles with the solu-tion or dispersion until the active ingredients are deposited in or on the carrier. The coated particles may then be dried, for example, in an oven at about 110C. Various other methods of catalyst preparation known to those skilled in the art may be used. Very useful carriers (and dilutants) are fused aluminas (Alundum*), silica, silicon carbide (Carborundum*), pumice, kiesel-guhr, asbestos, zeolites, and the like. The fused aluminas or other alumina carriers and silica are particularly preferred.
The carriers may be of any shape, including irregular shapes.
Another method for introducing the required surface is to utilize as a reactor a small diameter tube wherein the tube wall is catalytic or is coated with catalytic material. If the tube wall is the only source of catalyst, the tube wall will generally be of an internal diameter of no greater than one inch, * Trademarks 57~1 SUCIl as le~, than 3/4 inch in diaineter, or prefer~bly will be no greater than about 1/2 inch in diameter.
Othel methods may be utilized to introduce the catalytic surface. For example, the techniqlle of a fluidized bed may be used.
The concentration of H2S in the streams treated may vary widely. Thus, the concentrations may range from trace quantities to quite significant amounts, and it will be recognized by those skilled in the art that H2S concentrations are not generally a limiting factor of the invention. For example, con-centrations of H2S in the gases treated may range from 0.005% to 5.0%, or even 10.0% (molar basis).
Concentrations of COS and CS2 present in Claus effluents are normally also minor~ and will range for example from about 0.01% to about 0.5% (molar basisj.
Reaction conditions ernployed may vary con-siderably. While the temperatures at which the re-action is carried out are not critical, it is an advantage of the invention that lower or more moder-ate temperatures may be employed. Temperatures of 150C to 450C are quite satisfactory, while temper-atures of 250C to 420C are preferred.
Similarly, the pressures employed are not critical, and a wide range of pressures may be used.
~1~5731 tll~ t~t~ ss~lre i~l t~ ,y~t~i.l Or th~
invelltiOIl normally will be at or in excess of~ at-mospllei~ic pressure, altllo-lgh in some embodimen~,s, a partial vacuum may be used. Preferably, pressures will range from atmospheric to higher pressures, such as 5 or even 10 atmospheres. Steam may be present in the system, and in some instances, is preferred.
The flow rates of the H2S-containing gas and the oxygen are largely a matter of choice. However, as will be recognized by those skilled in the art, lower space velocities improve conversion levels. Generally, gaseous flow rates of from about 1,000 GHSV to about 50,000 GHSV may be used, with rates of from 2,000 GHSV
to about 25,000 GHSV being preferred. Good results have been obtained with space velocities of 2,000 to 10,000 GHSV. Contact times, accordingly, are widely variable, and may range from 0.07 seconds to about 4.0 seconds, with contact times of from about 0.14 seconds to about
L~ L` f ` .l ~lt;.~ o ~ :L' O C f ~ ., .[ ( ) f" t, lf l f ` ' ~ t~llJ~
i~C.i~ iiOII o.L` hydrogcn u:lp~-l;d~-contain:in~ wast- frascs i~ cont~cii.nf, s~.i.d wastl^ ga.;es wi.~h a scoichiometr c excess o 1' OXygf n Wi tn recpect to the containf_d hydrogen sulphide in the presence of a catalyst. It also relates to a eatalyst comp.)si.tion which can suitabl.y be applifd in such a process.
Viewed i.n the light of increasingly stringent re-quirements with respect to air pollution abateme.nt, various procedures have been developed to remove hydrogen sulphide (H2S) from proeess off-gases, and even reeover, if possible, H2S or reaetion products of H2S contained therein. For example, the well-known Claus process produees an effluent normally eontaining up to 2% or even 3% by weight sulphur eompounds, a substantial proportion thereof being H2S.
To remove this eoneentration of sulphur eompounds, seleetive absorption by eontaeting the Claus off-gases with a suitable absorption solvent, after a hydrogen-ation treatment of the off-gases, has been practised.
In this proeedure, the bulk of the desorbed H2S after regeneration of the absorption solvent, is returned to the Claus unit, and the final off-gas or tail gas, eontaining nitrogen, C02 and quite minor amounts of H2S is incinerated. During incineration, H2S is con-ver~ced to sulphur dioxide (S02), a material which ~1~S731 as rig;~d ;lS those apr)l-ic(l to ll2~. IIowcver, ;ncirIcratic)n is costly because of the necQssary heat input. Again, al.houg'l some work has been done with regard to catalytic conversion of H2S in the off-gas or tail gas to S02, concomi-tant formation of sulphur trioxide (S03) has been a problem.
A process is known for the purification of gases contaminated with hydrogen sulphide by oxidizing said hydrogen sulphide in the presence of catalysts which contain as the main constituents metals, such as niekel, iron, cobalt, manganese, zine and eopper, or their eompounds, either alone or together with metals or metalloids of Groups 4, 5 and 6 of the Periodie System of Elements and in addition thereto, small quantities of an aetivating material, such as lead or bismuth or their compounds, or alkali metal or alkaline earth metal compounds. The amount of the aetivating material employed is up to about 10%, based on the weight of the total amount of metals present.
Said known eatalysts have a disadvantage in that their aetivity deereases rapidly~ requiring a temperature raise of about 5C every three days. Moreover, about 10~ of the hydrogen sulphide present is eonvertc-d to S03~ whieh is a highly objectionable compound from an air pollution-abatement point of view.
~1~25731 Accoriingly, there still exists a need for an economical method for the purificatioll of i-12S-containing streams, particularly off-gas streams of the type mentioncd, which method would provide substantial conversion of the H~S values in the off-gas, and concomitantly provide low SO3 emissions.
The method should be economical in that the necessary heat input should be as low as possible as evidenced by relatively low process temperatures.
~breover, the catalysts to be applied should show an activity which remains constant over a long period.
The present invention has as its object to satisfy that need.
The present invention accordingly relates to a process for the catalytic incineration of hydrogen sulphide-containing waste gases by con-tacting said waste gases with a stoichiometric excess of oxygen with respect to the contained hydrogen sulphide in the presence of a catalyst in which process the hydrogen sulphide-containing waste gases are contacted with oxygen at a temperature in the range of from 150 to 450C in the presence of a catalyst comprising as the catalytically active components bismuth in an amount of from 0.6 to 10% by weight and copper in an amount of from 0.5 to 5% by weight, based on the total weight of the catalyst.
~1~57;~1 Z -i slZ~ r~ ~ ~)( rl ~:c,~ cl tilat ~ o r a catalyst contain;n~r both bismuth (Bi) anc1 copper (Cu), in spt?cifit-d proportions and amounts, givr-s resultc not att?illablt? by use of comparable arnounts of Cu or Bi alone. The une~pected aspect of the process of the invent:ion resides in the ability to utiliz? temper-atures of reaction not attainable, on a weight basis, with catalysts of Cu or Bi alone. Additionally, any combustibles, e.g., H2, C0, CH4, present in the streams to be treated appear unaffected or substantially unaffected by the catalyst of the invention. The S02 r^ormed may be vented or recovered in a manner known to those skilled in the art.
Although the invention is apparently applicable to any H2S-containing stream of low to moderate H2S
concentration, the invention is ideally suited to the treatment of H2S-containing off-gases fronZ various processes from which no further or little recovery of other materials is made. The invention is eminently suited, as indicated, to the treatment of the effluent from a Claus plant. The Claus process is normally itself a "clean-up" process, wherein elemental sulphur is prepared by partial oxidation of H2S, using an oxygen-containing gas (including pure oxygen) to form S02, followed by the reaction of S02 produced with the remaining part of the H2S, in the presence of a catalyst.
11~5731 i'`l~` `~)I~C `.: iS fI~ IIen'C~.y used clt rei irleri . ~ind al; o ior t;~-1e ioric-ul) oi`ll2S recovered from various gas Stl'eamS, such as natural gas. Since the yield of elem-ental sulpl1ur, relative to the hydrogen sulphide introduced, is not quantitative, a minor amount of unreacted H2S, COS, CS2, and S02 remains in the Claus off-gases. To some extent, the amount of elemental sulp}1ur recovered depends on the number of catalyst beds employed in the Claus process. In lQ principle, about ~% of the total sulphur available can be recovered when three catalyst beds are used.
The invention is eminently suited to the removal of H2S from Claus plant effluents.
Additionally, as indicated, Claus plant effluents or Claus off-gases may previously have been processed by a Claus tail gas treating process. Such a process may comprise the steps of reducing S02, COS, CS2, and S03 contained in the gas under suitable conditions to H2S in the presence of a catalyst, absorbing the H2S, followed by desorption of the H2S and recycle of the desorbed H2S to the Claus plant. Where this procedure is practised, the invention provides for the oxidation of the quite miinor or reduced ~mounts of H2S, and the like, remaining -in the final off-gas by contacting said off-gas with oxygen under the conditions indicated.
~125731 'ih~ talyst e~ loycd :in tl,c pro~es. jf th~ :in-v lltiOIl ~ )c a sol;cl mattrial containing copper alld bismutrl as the catalytically active components.
The particular form ~.Aiherein the catalytically acti-~e components are present in the catalyst, i.e., whether as compounds or the elements or compounds combined in a carrier material, does not appear to be critical.
Where a carrier is employed, the only apparent re-quirement concerning the sources of the copper and bismuth is that the copper and bismuth be in a form adapted to solution, either as an ordinary solution (both aqueous and organic solvents) or as a solution of a liquid or complex of copper or bismuth. Certain salts and the oxide and hydroxide of copper and bismuth may change cduring the preparation of the catalyst, during heating in a reactor prior to use in the process of -this invention, or may be converted to another form under the described reaction conditions, but such materials still function as effective catalysts in the defined process. For example, the nitrates, nitrites, carbonates, hydroxides, citrates and acetates may be converted to the corresponding oxide and then to the sulphide under the reaction conditions defined herein. Such salts as the phosphate, sulphate, halides, and the li~e, which are stable or partially stable at the defined reaction temperature, are 1~573~
similarly effective under the conditions of the described reaction, as well as such compounds which are converted to another stable form in the reactor.
Copper nitrate and bismuth nitrate are, however, preferred materials, since they are inexpensive and are readily soluble in water and can easily be deposited on carriers. The catalysts of this invention are solid at room temperature or are essentially solid under the conditions of reaction (although some volatilization may occur).
To achieve meaningful lowering of the reaction temperature with concomitant COS conversion the presence of minimum amounts of Cu and Bi is essential. In general, concentrations of at least 0.5% Cu and 0.6% Bi (all by weight) are required in the reaction zone, with concentrations of at least 0.8% Bi being preferred. Dramatic improvement over the Cu and Bi alone occurs when the concentration of Cu is at least about 1.0% and the con-centration of Bi is at least about 2.0% (all by weight). Where a carrier is employed, for example, the Cu will normally be present in an amount of up to about 5% by weight, based on the total weight of the catalyst material.
Preferably, the amount of Cu will not exceed about 3% by weight and the amount of Bi, preferably, does not exceed 5% by weight. It is preferred, however, that the amount of bismuth 112573~
p~.ent in th~` c;.t,alyst; :iS a]W~ly.. 'UlCIl t,h'lt, t,l-l''`
ce t;;',l~''it COIIlpI'i '>~`S cl major amc~urlt of bismllth and a IllillOr ;lr.lOUnt of copper.
If solid compouncls of Cu and Bi are employed, or if heavy concentrations of Cu and Bi on a carrier are employed, the catalytically active materials will normally be diluted with inert rnaterials so that activity may be regulated. Proper dilution to the concentrations specified is within the skill of the art, and need not be detailed herein.
Excellent results have been obtained by packing the reactor with the defined catalyst particles as the method of introducing the catalytic surface. The size of the catalyst particles may vary widely, but generally the maximum particle size will at least pass through a Tyler standard screen which has an opening of 2 inches, and the largest particles of catalyst will pass through a Tyler screen with one inch openings. Very small particle size carriers may be utilized, the only practical objection being that extremely small particles cause excessive pressure drops across the reactor. In order to avoid high pressure drops across the reactor, at least 50% by weight of the catalyst should be retained by a 4 to 5 rnesh Tyler standard screen. However, if a fluid bed reactor is utilized, catalyst particles may be quite small, such as from about 10 to 300 microns. Those skilled in the art can readily determine appropriate particle slze depending on reactor configuration and size, and gas velocity to be applied.
If a carrier is used, the catalytically active compon-ents may be deposited on the carrier by methods known in the art, such as by preparing in aqueous solution or dispersion of the des-cribed catalyst, and mixing the carrier particles with the solu-tion or dispersion until the active ingredients are deposited in or on the carrier. The coated particles may then be dried, for example, in an oven at about 110C. Various other methods of catalyst preparation known to those skilled in the art may be used. Very useful carriers (and dilutants) are fused aluminas (Alundum*), silica, silicon carbide (Carborundum*), pumice, kiesel-guhr, asbestos, zeolites, and the like. The fused aluminas or other alumina carriers and silica are particularly preferred.
The carriers may be of any shape, including irregular shapes.
Another method for introducing the required surface is to utilize as a reactor a small diameter tube wherein the tube wall is catalytic or is coated with catalytic material. If the tube wall is the only source of catalyst, the tube wall will generally be of an internal diameter of no greater than one inch, * Trademarks 57~1 SUCIl as le~, than 3/4 inch in diaineter, or prefer~bly will be no greater than about 1/2 inch in diameter.
Othel methods may be utilized to introduce the catalytic surface. For example, the techniqlle of a fluidized bed may be used.
The concentration of H2S in the streams treated may vary widely. Thus, the concentrations may range from trace quantities to quite significant amounts, and it will be recognized by those skilled in the art that H2S concentrations are not generally a limiting factor of the invention. For example, con-centrations of H2S in the gases treated may range from 0.005% to 5.0%, or even 10.0% (molar basis).
Concentrations of COS and CS2 present in Claus effluents are normally also minor~ and will range for example from about 0.01% to about 0.5% (molar basisj.
Reaction conditions ernployed may vary con-siderably. While the temperatures at which the re-action is carried out are not critical, it is an advantage of the invention that lower or more moder-ate temperatures may be employed. Temperatures of 150C to 450C are quite satisfactory, while temper-atures of 250C to 420C are preferred.
Similarly, the pressures employed are not critical, and a wide range of pressures may be used.
~1~5731 tll~ t~t~ ss~lre i~l t~ ,y~t~i.l Or th~
invelltiOIl normally will be at or in excess of~ at-mospllei~ic pressure, altllo-lgh in some embodimen~,s, a partial vacuum may be used. Preferably, pressures will range from atmospheric to higher pressures, such as 5 or even 10 atmospheres. Steam may be present in the system, and in some instances, is preferred.
The flow rates of the H2S-containing gas and the oxygen are largely a matter of choice. However, as will be recognized by those skilled in the art, lower space velocities improve conversion levels. Generally, gaseous flow rates of from about 1,000 GHSV to about 50,000 GHSV may be used, with rates of from 2,000 GHSV
to about 25,000 GHSV being preferred. Good results have been obtained with space velocities of 2,000 to 10,000 GHSV. Contact times, accordingly, are widely variable, and may range from 0.07 seconds to about 4.0 seconds, with contact times of from about 0.14 seconds to about
2.0 seconds being preferred.
The amount of oxygen supplied to the reaction zone is important, in that a stoichiometric excess, prefer-ably a large excess, of oxygen is desired in order to react all the H2S and any COS and CS2 present. In general, at least twice, and normaIy up to five times the stoichiometric arnount of oxygen required for the reaction may be supplied. Preferably, an excess of 1~573~
about .'0 to a~out 2~0,' of` the stoichio111et-ric a1-nourlt o, oxy~en, based upon all total combustibles, will be supplied. Amounts as high as lOO or even 20Q times the stoichiometric amount of oxygen may be supplied, if desired. The oxygen may be supplied as relatively pure oxygen, as air, or mixtures of air and oxygen, as well as from other gaseous streams containing significant quantities of oxygen and other com-ponents which do not interfere significantly with the reaction contemplated.
EXA~iPLE I
In order to demonstrate the invention, the following experiments were conducted. In each run, a synthetic tail gas containing H2S and other sulphur compounds is passed into a reactor containing the catalyst. Oxygen, as air, is introduced from a separate line. Temperature is measured by suitable means, and conversion results are obtained by analysis of the effluent stream from the reactor.
Employing this general procedure, samplings were ta~en employing a catalyst containing Bi and Cu deposited on alumina (Kaiser A-201 spherical gamma-alumina, l~ x 6 mesh) in amounts of 3% and 1%
respectively, each by weight, based on the total weight of the catalyst. Copper and bismuth were deposited as a basic solution of the nitrates. The catalyst was then ~573~
dl~ie(l .ln(i c;~ ;nt~d ~t 4dlC for ono to t~o hc,urs b~rore~
use. Con(lition, or operation are shown more speci-fically -in Table I. Significant H2S-removal is ob-tained, and the results for two di.fferent space velocities are shown in Table II.
TABLE I
Composition, %v H2S o.8 S2 0.4 S1 0.15 COS 0 o4 CS2 0.04 C2 5.00 C0 0.50 H2 1.00 Air variable N2 remainder _perating conditions Pressure : 1 atmosphere Temperature : 290-425C
Space velocity: 2500 to 5000 vol./vol./h (basis reactor outlet) Air rate : 20-2c30% excess 2 ~) ~) Based upon all total combustibles, including hydro,,en.
573~
TABl.E II
Catalyst 1% Cu - 3% Bi/A1203 Space velocity, ; vol./vol./h 2500 5000 Temperature, C 370 370 Excess 2' ~ 150 150 Wet chemical analysis Product gas (dry basis) H2S~ ppmv 0.1 0.7 S2~ %v 2.23 1.95 S03, ppm~ 6 14 EXAMPLE II
Employing a procedure similar to Example I, a catalyst containing only 3% by weight (based on the weight of the active material and carrier) bismuth on alumina and a catalyst containing only 1% by weight (based on the weight of the active material and carrier) copper on alumina were prepared and tested.
Results are shown in Table III and compared with those for a catalyst in accordance with the invention.
1~5'7;~1 'l'.~l3rE -[IL
Co~ilparison of cata]yst compositions Catalyst 3%i/Al203 1% Cu/A1203 1% Cu-3,~ Bi/Al20 Space velocity, vol./vol./h -2500 Temperature, C 315 Exeess 2' % 150 Wet chemical analysis Product gas (dry basis) H2S,ppmv 2.1 0.1 0.14 S02, %v 2.18 2.04 2.10 S03, ppmv 22 71 8 The data in Table III demonstrate clearly the superiority of the Cu - Bi catalyst with respect to the reduced S03-concentration in the product gas. The com-bination eatalyst in accordance with the invention also shows a very high conversion for carbonyl sulphide and earbon disulphide. At the reaetion eonditions specified the carbonyl sulphide conversion is better than 50% and the earbon disulphide eonversion is better than 90%.
The amount of oxygen supplied to the reaction zone is important, in that a stoichiometric excess, prefer-ably a large excess, of oxygen is desired in order to react all the H2S and any COS and CS2 present. In general, at least twice, and normaIy up to five times the stoichiometric arnount of oxygen required for the reaction may be supplied. Preferably, an excess of 1~573~
about .'0 to a~out 2~0,' of` the stoichio111et-ric a1-nourlt o, oxy~en, based upon all total combustibles, will be supplied. Amounts as high as lOO or even 20Q times the stoichiometric amount of oxygen may be supplied, if desired. The oxygen may be supplied as relatively pure oxygen, as air, or mixtures of air and oxygen, as well as from other gaseous streams containing significant quantities of oxygen and other com-ponents which do not interfere significantly with the reaction contemplated.
EXA~iPLE I
In order to demonstrate the invention, the following experiments were conducted. In each run, a synthetic tail gas containing H2S and other sulphur compounds is passed into a reactor containing the catalyst. Oxygen, as air, is introduced from a separate line. Temperature is measured by suitable means, and conversion results are obtained by analysis of the effluent stream from the reactor.
Employing this general procedure, samplings were ta~en employing a catalyst containing Bi and Cu deposited on alumina (Kaiser A-201 spherical gamma-alumina, l~ x 6 mesh) in amounts of 3% and 1%
respectively, each by weight, based on the total weight of the catalyst. Copper and bismuth were deposited as a basic solution of the nitrates. The catalyst was then ~573~
dl~ie(l .ln(i c;~ ;nt~d ~t 4dlC for ono to t~o hc,urs b~rore~
use. Con(lition, or operation are shown more speci-fically -in Table I. Significant H2S-removal is ob-tained, and the results for two di.fferent space velocities are shown in Table II.
TABLE I
Composition, %v H2S o.8 S2 0.4 S1 0.15 COS 0 o4 CS2 0.04 C2 5.00 C0 0.50 H2 1.00 Air variable N2 remainder _perating conditions Pressure : 1 atmosphere Temperature : 290-425C
Space velocity: 2500 to 5000 vol./vol./h (basis reactor outlet) Air rate : 20-2c30% excess 2 ~) ~) Based upon all total combustibles, including hydro,,en.
573~
TABl.E II
Catalyst 1% Cu - 3% Bi/A1203 Space velocity, ; vol./vol./h 2500 5000 Temperature, C 370 370 Excess 2' ~ 150 150 Wet chemical analysis Product gas (dry basis) H2S~ ppmv 0.1 0.7 S2~ %v 2.23 1.95 S03, ppm~ 6 14 EXAMPLE II
Employing a procedure similar to Example I, a catalyst containing only 3% by weight (based on the weight of the active material and carrier) bismuth on alumina and a catalyst containing only 1% by weight (based on the weight of the active material and carrier) copper on alumina were prepared and tested.
Results are shown in Table III and compared with those for a catalyst in accordance with the invention.
1~5'7;~1 'l'.~l3rE -[IL
Co~ilparison of cata]yst compositions Catalyst 3%i/Al203 1% Cu/A1203 1% Cu-3,~ Bi/Al20 Space velocity, vol./vol./h -2500 Temperature, C 315 Exeess 2' % 150 Wet chemical analysis Product gas (dry basis) H2S,ppmv 2.1 0.1 0.14 S02, %v 2.18 2.04 2.10 S03, ppmv 22 71 8 The data in Table III demonstrate clearly the superiority of the Cu - Bi catalyst with respect to the reduced S03-concentration in the product gas. The com-bination eatalyst in accordance with the invention also shows a very high conversion for carbonyl sulphide and earbon disulphide. At the reaetion eonditions specified the carbonyl sulphide conversion is better than 50% and the earbon disulphide eonversion is better than 90%.
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the catalyst incineration of hydrogen sulphide-containing waste gases by contacting said waste gases with a stoichiometric excess of oxygen with respect to the contained hydrogen sulphide in the presence of a catalyst, in which the hydrogen sulphide-containing waste gases are contacted with oxygen or an oxygen-containing gas at a temperature in the range of from 150 to 450°C in the presence of a catalyst compris-ing as the catalytically active components bismuth in an amount of from 0.6 to 10% by weight and copper in an amount of from 0.5 to 5% by weight, based on the total weight of the catalyst.
2. A process as claimed in claim 1, wherein the catalyst comprises of from 0.8 to 5% by weight of bismuth and of from 0.5 to 3% by weight of copper.
3. A process as claimed in claim 1 or 2 wherein the weight percent of bismuth exceeds the weight percent of copper.
4. A process as claimed in claim 1 wherein the oxygen is supplied in an amount of up to 5 times the stoichiometric amount of oxygen required.
5. A process as claimed in claim 1 or 4 in which the oxy-gen is supplied in an excess of 20% to 280% of the stoichiometric amount of oxygen.
6. A process as claimed in claim 1, wherein the hydrogen sulphide-containing waste gas is a Clause off-gas.
7. A process as claimed in claim 1, wherein the hydrogen sulphide-containing waste gas is an off-gas of a Clause tail gas-treating process.
8. A process as claimed in claim 1 wherein the hydrogen sulphide-containing waste gas comprises of from 0.005 up to 5.0% mol. H2S.
9. A process as claimed in claim 1, wherein the contacting temperature is from 250° to 420°C.
10. A catalyst composition comprising a carrier material and copper and bismuth as the catalytically active components, copper being present in an amount of from 0.5 to 5% by weight and bismuth in an amount of from 0.6 to 10% by weight, based on the total weight of the catalyst composition, and wherein the weight percent of bismuth exceeds the weight percentage of copper.
11. A catalyst composition as claimed in claim 9 wherein the carrier material is chosen from the group comprising fused aluminas, silica and alumina.
12. A catalyst composition as claimed in claim 9 comprising 0.5 to 3.0% by weight of copper and 0.8 to 5.0% by weight of bismuth, the carrier material being alumina.
13. A catalyst composition as claimed in claim 10 or 11, wherein the carrier material is gamma-alumina.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US75753177A | 1977-01-07 | 1977-01-07 | |
| US757,531 | 1977-01-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1125731A true CA1125731A (en) | 1982-06-15 |
Family
ID=25048172
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA294,517A Expired CA1125731A (en) | 1977-01-07 | 1978-01-06 | Process for the catalytic incineration of hydrogen sulphide-containing waste gases and a catalyst composition therefor |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5377873A (en) |
| AR (1) | AR212728A1 (en) |
| AU (1) | AU510872B2 (en) |
| BE (1) | BE862443A (en) |
| BR (1) | BR7800064A (en) |
| CA (1) | CA1125731A (en) |
| DE (1) | DE2754762A1 (en) |
| FR (1) | FR2376686A1 (en) |
| GB (1) | GB1558656A (en) |
| MY (1) | MY8100349A (en) |
| NL (1) | NL190357C (en) |
| RO (1) | RO76367A (en) |
| ZA (1) | ZA7850B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4576814A (en) * | 1979-04-04 | 1986-03-18 | Union Oil Company Of California | Catalyst and process for oxidizing hydrogen sulfide |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0085213B1 (en) * | 1982-02-02 | 1990-02-07 | Union Oil Company Of California | Catalyst and process for oxidizing hydrogen sulfide |
| FR2631854A1 (en) * | 1988-05-26 | 1989-12-01 | Norsolor Sa | PROCESS FOR THE CATALYTIC PURIFICATION OF AN AQUEOUS EFFLUENT |
| JP2000515807A (en) * | 1996-07-26 | 2000-11-28 | シエル・インターナシヨネイル・リサーチ・マーチヤツピイ・ベー・ウイ | Catalyst composition, its preparation and its use in catalytic ashing |
| DE69705525T2 (en) * | 1996-07-26 | 2001-11-29 | Shell Int Research | METHOD FOR CATALYTIC COMBUSTION AND CATALYST COMPOSITION USED THEREFOR |
| WO2002032810A1 (en) | 2000-10-18 | 2002-04-25 | Jgc Corporation | Method and apparatus for removing sulfur compound in gas containing hydrogen sulfide, mercaptan, carbon dioxide and aromatic hydrocarbon |
| IT1403545B1 (en) * | 2011-02-02 | 2013-10-31 | Eonsudenergia Srl | CATALYST FOR WASTE THERMOLYSIS |
| EP3799854A1 (en) | 2019-10-01 | 2021-04-07 | Stefan Johannes Fellner | Extract of organic humified materials |
| CN113117517B (en) * | 2019-12-31 | 2022-10-11 | 中国石油化工股份有限公司 | Treatment method of high-concentration sulfur-containing organic waste gas |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1900751A (en) * | 1928-02-27 | 1933-03-07 | Ig Farbenindustrie Ag | Purification of gases |
| GB319396A (en) * | 1928-06-20 | 1929-09-20 | Ig Farbenindustrie Ag | Improvements relating to the purification of gas containing sulphuretted hydrogen |
| FR1070681A (en) * | 1953-02-06 | 1954-08-05 | Bataafsche Petroleum | Process for preparing sulfur from hydrogen sulfide |
-
1977
- 1977-12-08 DE DE19772754762 patent/DE2754762A1/en active Granted
- 1977-12-29 BE BE1008616A patent/BE862443A/en not_active IP Right Cessation
-
1978
- 1978-01-05 NL NLAANVRAGE7800126,A patent/NL190357C/en not_active IP Right Cessation
- 1978-01-05 AR AR270636A patent/AR212728A1/en active
- 1978-01-05 JP JP5678A patent/JPS5377873A/en active Granted
- 1978-01-05 ZA ZA00780050A patent/ZA7850B/en unknown
- 1978-01-05 GB GB368/78A patent/GB1558656A/en not_active Expired
- 1978-01-05 RO RO7892830A patent/RO76367A/en unknown
- 1978-01-05 BR BR7800064A patent/BR7800064A/en unknown
- 1978-01-05 AU AU32198/78A patent/AU510872B2/en not_active Expired
- 1978-01-05 FR FR7800205A patent/FR2376686A1/en active Granted
- 1978-01-06 CA CA294,517A patent/CA1125731A/en not_active Expired
-
1981
- 1981-12-30 MY MY349/81A patent/MY8100349A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4576814A (en) * | 1979-04-04 | 1986-03-18 | Union Oil Company Of California | Catalyst and process for oxidizing hydrogen sulfide |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6120342B2 (en) | 1986-05-21 |
| RO76367A (en) | 1981-11-04 |
| NL190357B (en) | 1993-09-01 |
| FR2376686B1 (en) | 1982-05-07 |
| AU510872B2 (en) | 1980-07-17 |
| BR7800064A (en) | 1979-01-02 |
| AR212728A1 (en) | 1978-09-15 |
| JPS5377873A (en) | 1978-07-10 |
| NL190357C (en) | 1994-02-01 |
| MY8100349A (en) | 1981-12-31 |
| NL7800126A (en) | 1978-07-11 |
| FR2376686A1 (en) | 1978-08-04 |
| GB1558656A (en) | 1980-01-09 |
| DE2754762A1 (en) | 1978-07-13 |
| AU3219878A (en) | 1979-07-12 |
| BE862443A (en) | 1978-06-29 |
| ZA7850B (en) | 1978-12-27 |
| DE2754762C2 (en) | 1987-02-05 |
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