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  • 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
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8603—Removing sulfur compounds
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  • B01D53/8606—Removing sulfur compounds only one sulfur compound other than sulfur oxides or hydrogen sulfide
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  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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  • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
  • B01J23/42—Platinum
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  • B01J23/44—Palladium
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  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/74—Iron group metals
  • B01J23/75—Cobalt
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  • B01J23/74—Iron group metals
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  • 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
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/88—Molybdenum
  • B01J23/882—Molybdenum and cobalt
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  • 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
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/88—Molybdenum
  • B01J23/883—Molybdenum and nickel
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  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/19—Catalysts containing parts with different compositions
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
  • C10K1/00—Purifying combustible gases containing carbon monoxide
  • C10K1/34—Purifying combustible gases containing carbon monoxide by catalytic conversion of impurities to more readily removable materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2251/00—Reactants
  • B01D2251/20—Reductants
  • B01D2251/202—Hydrogen
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  • B01D2255/10—Noble metals or compounds thereof
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  • B01D2255/1023—Palladium
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  • B01D2255/20746—Cobalt
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2255/20753—Nickel
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  • B01D2255/20769—Molybdenum
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  • B01D2255/20776—Tungsten
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/209—Other metals
  • B01D2255/2092—Aluminium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/80—Type of catalytic reaction
  • B01D2255/808—Hydrolytic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/30—Sulfur compounds
  • B01D2257/306—Organic sulfur compounds, e.g. mercaptans
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/30—Sulfur compounds
  • B01D2257/308—Carbonoxysulfide COS
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
  • B01D2257/702—Hydrocarbons

Definitions

• the invention relates to a gas treatment process which comprises in particular as impurities to eliminate sulfur compounds.
• the method applies to the treatment of effluent gas from furnaces of coal black production unit.
• Sulfur encountered in industrial waste gases for example in gases from gasification units of coal or petcoke or biomass or in the gases from calcining furnaces of carbon black production units, are generally found in the form of sulfur dioxide, hydrogen sulphide and carbon disulfide, such as carbon disulfide (CS 2 ) and carbonyl sulphide (COS).
• Carbon sulfides are relatively inert compounds and thus remain difficult to remove from the effluent effectively.
• document US Pat. No. 5,466,427 discloses a process for treating a sulfur-containing waste gas, in particular in the form of carbon disulphide, which comprises bringing said gas into contact with a catalyst in order to carry out a hydrolysis of carbon disulphide ( CS 2 ) and carbonyl sulphide (COS) to hydrogen sulphide.
• the catalyst described in this document comprises:
• the process of the prior art works properly provided that the gas to be treated comprises a relatively small amount of unsaturated hydrocarbon products (in particular compounds of the alkyne and diene type), that is to say a maximum concentration of 50 ppm, or even 30 ppm by volume.
• unsaturated hydrocarbon products in particular compounds of the alkyne and diene type
• EP 2 662 127 of the applicant discloses a gas treatment process for converting the sulfur compounds present in said gas, especially in the form of CS2 and / or COS, which comprises the following steps:
• a catalytic hydrolysis in the presence of water of the COS and / or CS2 present in the effluent from step a) so as to provide an effluent rich in H 2 S, by contacting the effluent from step a) with a hydrolysis catalyst, the hydrolysis catalyst comprising alumina or titania.
• This document gives as an example a catalyst comprising nickel (2.5% by weight of NiO), molybdenum (9% by weight of MoO 3 ) deposited on a titanium oxide support (TiO 2 ).
• An object of the invention is to provide a method for treating a gas containing sulfur compounds present in said gas, especially in the form of CS 2 and / or COS alternative and which implements in particular a Hydrolysis-Hydrogenation step. more efficient.
• the invention therefore relates to a process for treating a gas comprising from 10 ppm by volume to 0.5% by volume of at least one of the COS and CS 2 compounds and from 30 ppm by volume to 5% by volume of compounds. unsaturated hydrocarbons, said process comprising the following steps:
• the hydrogenation catalyst comprising at least one metal chosen from palladium, platinum, nickel and cobalt deposited on a porous support,
• a catalytic hydrolysis-hydrogenation, in the presence of water and hydrogen, of the COS and / or CS 2 present in the effluent resulting from step a) is carried out so as to provide an effluent rich in H 2;
• S by contacting the effluent from step a) with a hydrolysis-hydrogenation catalyst, the hydrolysis-hydrogenation catalyst comprising a support consisting essentially of alumina, at least one Group VIII metal selected by nickel and cobalt, at least one Group VIB metal selected from molybdenum and tungsten and in which the content of group VI II metal, expressed as oxide, is between 1% and 10% by weight relative to the total weight of catalyst, in which the content of group VIB metal, expressed as oxide, is included between 3% and 20% by weight relative to the total weight of catalyst and in which the molar ratio (Group VI II metal) / (Group VIB metal) is between 0.4 and 2 (mol / mol).
• step a) of hydrogenation of the feedstock makes it possible to prevent the gradual deactivation or even clogging of the hydrolysis-hydrogenation catalyst of step b), especially following the formation of polymerization gums. on the surface of the catalysts.
• the unsaturated hydrocarbon compounds are converted by hydrogenation into compounds which are not capable of polymerizing and thus of causing poisoning, coking or clogging of the pores of the catalyst.
• hydrolysis-hydrogenation in the subsequent step b) resulting in an improved efficiency of the treatment process compared to the prior art.
• unsaturated hydrocarbon compounds includes in particular alkenes, alkynes and polyunsaturated compounds of the diene type.
• step b) improves the hydrolysis-hydrogenation yield of the sulfur compounds still present in the effluent generated. in step a).
• the hydrogenation catalyst comprises a platinum content, expressed as metal, of between 0.2% by weight and 4% by weight relative to the weight of catalyst.
• the hydrogenation catalyst comprises a palladium content, expressed as metal, of between 0.05% by weight and 5% by weight relative to the weight of catalyst.
• the hydrogenation catalyst comprises a nickel content, expressed as oxide, of between 0.5% by weight and 15% by weight relative to the weight of catalyst.
• the hydrogenation catalyst comprises cobalt
• the cobalt content expressed as oxide, is between 0.5% by weight and 15% by weight relative to the weight of catalyst.
• the hydrogenation catalyst further comprises molybdenum
• the molybdenum content, expressed as oxide, is between 1% and 20% by weight relative to the weight of catalyst.
• the hydrolysis-hydrogenation catalyst has a content of Group VI II metal, expressed as oxide, of between 1% and 8% by weight relative to total weight of catalyst. More preferably, the group VIII metal content, expressed as oxide, is between 3% and 7% by weight relative to the total weight of catalyst.
• the hydrolysis-hydrogenation catalyst has a content of Group VIB metal, expressed as oxide, of between 5% and 18% by weight relative to the total weight of catalyst. More preferably, the group VIB metal content is between 6% and 15% by weight relative to the total weight of catalyst.
• the hydrolysis-hydrogenation catalyst comprises cobalt and molybdenum.
• the support of the hydrolysis-hydrogenation catalyst consists essentially of alumina, that is to say that the Al 2 O 3 content is at least 98% by weight with respect to total weight of the support.
• the molar ratio (Group VIII metal) / (Group VIB metal) is between 0.4 and 1.5 (mol / mol).
• steps a) and b) are carried out in the same reactor in which two catalyst beds, namely a hydrogenation catalyst and a hydrolysis-hydrogenation catalyst, are successively arranged.
• the beds are arranged relative to each other in the reactor so that the feed to be treated meets the hydrogenation catalyst bed before the hydrolysis-hydrogenation catalyst bed.
• the method uses two reactors (ie a hydrogenation reactor and a hydrolysis-hydrogenation reactor) and in which the hydrogenation reactor is installed downstream of the hydrolysis reactor. -hydrogénation.
• steps a) and b) are carried out with catalysts of identical formulation comprising a support consisting essentially of alumina, at least one metal of group VIII chosen by nickel and cobalt, at least a Group VIB metal selected from molybdenum and tungsten, preferably a nickel or cobalt catalyst. More preferably, the catalysts are based on cobalt and molybdenum.
• step a) is carried out at a pressure of between 0.1 and 5 MPa and a VVH of between 1000 and 4000 h -1 .
• step b) is carried out at a pressure of between 0.1 and 5 MPa and a VVH between 1000 and 4000 h -1 .
• the process according to the invention comprises a step of treating the gas resulting from the hydrolysis-hydrogenation step which consists, for example, of trapping the H 2 S formed or of converting the H 2 S in elemental sulfur.
• the gas that can be treated by the process according to the invention may be derived from coal or petcoke gasification units or from biomass or calcination furnaces of carbon black production units.
• the gas to be treated may comprise COS and / or CS 2 at a content of between 10 ppm by volume and 0.5% by volume.
• the gas thus comprises COS at a content most often between 10 ppm by volume and 0.3% by volume, CS 2 at a content of between 10 ppm volume and 0.3% volume and optionally HCN at a concentration of content between 20 ppm by volume and 0.2% by volume.
• the gas may also include hydrogen, CO, SO 2 , CO 2 , H 2 S and water.
• the gas generally comprises unsaturated hydrocarbons at a content of between 30 ppm by volume and 5% by volume, preferably between 0.05 and 3% by volume.
• the unsaturated hydrocarbon compounds essentially comprise short-chain hydrocarbon products, typically C2, C3 or C4, of the alkenes, alkynes and polyunsaturates family, such as, for example, ethylene, acetylene, butadiene.
• the hydrogenation can be selective, that is to say only concern alkynes and polyunsaturated dienes type but not mono-olefins.
• total hydrogenation i.e., hydrogenating all unsaturated compounds, including mono-olefins to paraffins.
• the hydrogenation catalyst used in step a) comprises a metal chosen from platinum, palladium, nickel and cobalt alone or as a mixture and deposited on a porous support.
• the hydrogenation catalyst comprises platinum, and the platinum content, expressed in metal, is typically between 0.02% by weight and 4% by weight relative to the total weight of catalyst.
• the platinum content is between 0.05% and 3% by weight, more preferably between 0.1% and 2.5% by weight relative to the total weight of catalyst.
• the hydrogenation catalyst comprises palladium and the content of palladium, expressed in metal, is between 0.05% by weight and 5% by weight relative to the total weight of catalyst.
• the palladium content is between 0.05 and 3% by weight, and more preferably between 0.1% by weight and 1% by weight relative to the total weight of catalyst.
• the hydrogenation catalyst comprises nickel and the nickel content is generally between 0.5% by weight and 15% by weight of nickel oxide relative to the total weight of catalyst.
• the nickel oxide content is between 4% and 12% by weight, more preferably between 6% and 10% by weight relative to the total weight of catalyst.
• the hydrogenation catalyst comprises cobalt and the cobalt content is generally between 0.5% by weight and 15% by weight of cobalt oxide relative to the total weight of catalyst.
• the content of cobalt oxide is between 1% and 10% by weight, more preferably between 2% and 4% by weight relative to the total weight of catalyst.
• the hydrogenation catalyst contains either platinum, palladium, nickel or cobalt and may further comprise molybdenum.
• the content, expressed as molybdenum oxide, of said catalyst is between 1% by weight and 20% by weight relative to the total weight of catalyst, preferably between 6% and 18% by weight, and more preferably between 8% by weight. and 15% by weight.
• the catalyst of step a) is a catalyst which further comprises a porous support on which are deposited the metal (s) or precursors of the active metals or oxides in hydrogenation.
• the support may be chosen from aluminas, silicas, titanium oxide, silicon carbide or their mixtures.
• the porous support is preferably chosen from alumina, nickel or cobalt aluminate, silica, silica-aluminas, silicon carbide, titanium oxide, or mixtures thereof. Pure alumina or titanium oxide is preferably used.
• the support consists essentially of cubic gamma alumina or delta alumina.
• the hydrogenation catalyst used in step a) comprises palladium. In another more preferred embodiment, it comprises nickel and molybdenum. Alternatively, the hydrogenation catalyst comprises cobalt and molybdenum.
• the catalyst according to the invention can be prepared using any technique known to those skilled in the art, and in particular by impregnation of the metal elements on the selected support. This impregnation may, for example, be carried out according to the method known to those skilled in the art in the dry-impregnation terminology, in which the quantity of desired elements in the form of soluble salts in the chosen solvent, for example demineralized water, so as to fill the porosity of the support as exactly as possible.
• the support thus filled with the solution is preferably dried.
• the preferred support is alumina or titania which can be prepared from any type of precursors and shaping tools known to those skilled in the art.
• a heat treatment which comprises a drying step followed by calcination.
• the drying is generally carried out under air between 20 ° C and 200 ° C, preferably between 40 ° C and 180 ° C.
• the calcination is generally carried out under air or with dilute oxygen, and the treatment temperature is generally between 200 ° C. and 550 ° C., preferably between 300 ° C. and 500 ° C.
• the hydrogenation step a) is carried out in the presence of hydrogen under the following operating conditions:
• step a) the amount of hydrogen added in step a) is such that the molar ratio between hydrogen and unsaturated hydrocarbon compounds to be hydrogenated or greater than stoichiometry and preferably between 1, 1 and 3000 moles per mole and preferably between 300 and 2000 moles per mole.
• the hydrolysis-hydrogenation catalyst implemented in step b) is a catalyst which comprises a support consisting essentially of alumina (that is to say that the Al 2 O 3 content is at least 98 % by weight relative to the total weight of the support) and at least one Group VIII metal selected from nickel and cobalt and at least one Group VIB metal selected from molybdenum and tungsten.
• the metal content of group VIII is between 1% and 10% by weight relative to the total weight of catalyst.
• the metal content of group VIB, expressed as oxide is between 3% and 20% by weight relative to the weight total of catalyst.
• the molar ratio (Group VIII metal) / (Group VIB metal) is between 0.4 and 2 (mol / mol).
• the hydrolysis-hydrogenation catalyst has a group VIII metal content, expressed as oxide, of between 1% and 8% by weight relative to the total weight of catalyst. More preferably, the group VIII metal content, expressed as oxide, is between 3% and 7% by weight relative to the total weight of catalyst.
• the hydrolysis-hydrogenation catalyst has a content of Group VIB metal, expressed as oxide, of between 5% and 18% by weight relative to the total weight of catalyst. More preferably, the group VIB metal content is between 6% and 15% by weight relative to the total weight of catalyst.
• the hydrolysis-hydrogenation catalyst comprises cobalt and molybdenum.
• the molar ratio (Group VIII metal) / (Group VIB metal) is between 0.4 and 1.5 (mol / mol).
• the alumina of the support is a cubic gamma alumina or a delta alumina.
• the catalyst may be prepared using any technique known to those skilled in the art, and in particular by impregnation of nickel precursors, cobalt, molybdenum, on the support which has been previously shaped.
• This impregnation may, for example, be carried out according to the method known to those skilled in the art in the terminology "dry impregnation", in which the quantity of desired elements in the form of soluble salts in the chosen solvent is introduced just by example of the demineralized water, so as to fill as accurately as possible the porosity of the support.
• the impregnated support may then be dried, preferably at a temperature of between 20 ° C and 200 ° C, more preferably between 40 ° C and 180 ° C. Calcination is then generally carried out under air or with dilute oxygen, and the calcination temperature is generally between 200 ° C. and 550 ° C., preferably between 300 ° C. and 500 ° C.
• the hydrolysis-hydrogenation catalyst is prepared by using a single impregnation to deposit each of the metals of the groups.
• the catalyst is prepared using a single step of co-impregnation of Group VIII metals and Group VIB.
• the hydrolysis-hydrogenation step is typically carried out at a pressure of between 0.1 and 5 MPa, preferably between 0.5 and 3 MPa, at a temperature of between 100 and 400 ° C., preferably of between 150 and 400 ° C. ° C and 250 ° C, and a volume of catalyst in relation to the amount of gas to be treated of 1 m 3 of catalyst per 1000 to 4000 Nm 3 / h of gas to be treated, a VVH between 1000 and 4000 h "1 .
• the operation is carried out in the presence of an excess of water relative to the molecules to be hydrolysed-hydrogenated.
• an excess of water relative to the molecules to be hydrolysed-hydrogenated.
• one operates with a hydrolysable water / hydrolysable product molar ratio of between 5 and 1000 moles per mole and more preferably between 10 and 500 moles per mole.
• the catalyst used is generally active in the carbon monoxide conversion reaction, which makes it possible to generate hydrogen according to the reaction: CO + H 2 O + CO 2 + H 2
• Fig.1 shows a first embodiment of the method according to the invention.
• Fig. 2 shows a second embodiment of the method according to the invention.
• Fig. 3 shows a third embodiment of the method according to the invention.
• the figures are not drawn to scale. Generally, similar elements are denoted by identical references in the figures.
• the process uses a first reactor 1 in which a catalyst for hydrogenation of the unsaturated compounds, preferably a selective hydrogenation catalyst, is present.
• a catalyst for hydrogenation of the unsaturated compounds preferably a selective hydrogenation catalyst. Any hydrogenation catalyst described above can be used in this embodiment.
• the gaseous feedstock to be treated is introduced into the reactor 1 via the line 3 while an additional quantity of hydrogen, in addition to the hydrogen initially present in the gas to be treated, may optionally be introduced into the reactor 1 through in line 4.
• the quantity of total hydrogen present in the gas to be treated and optionally added is such that the molar ratio between the hydrogen and the unsaturated hydrocarbon compounds to be hydrogenated is greater than the stoichiometry and preferably between 1, 1 and 3,000 moles per mole. and preferably between 300 and 2000 moles per mole.
• the hydrogenation step is generally conducted at a pressure of between
• the effluent from the hydrogenation reactor is then sent to the hydrolysis-hydrogenation reactor 2, via the line 5, in which is carried out the conversion of the sulfur compounds COS and CS 2 to H 2 S on a specific catalyst in the presence of water and hydrogen.
• water or hydrogen content of the feed is not sufficient, additional water or hydrogen may be introduced via line 6, in order to carry out the hydrolysis-hydrogenation with an excess of water relative to hydrolysable molecules (COS, CS 2 , HCN).
• the reactions involved during this step can be represented by the following reactions:
• the hydrolysis-hydrogenation step is typically carried out at a pressure of between 0.1 and 5 MPa, preferably between 0.5 and 3 MPa, at a temperature of between 100 and 400 ° C., preferably of between 150 and 400 ° C. ° C and 250 ° C, and a volume of catalyst in relation to the amount of gas to be treated of 1 m 3 of catalyst per 1000 to 4000 Nm 3 / h of gas to be treated, or a VVH between 1000 and 4000 h " 1 .
• the operation is carried out in the presence of an excess of water relative to the hydrolyzable-hydrogenatable molecule molecules.
• a hydrolysable water / hydrolysable product molar ratio of between 5 and 1000 moles per mole and more preferably between 10 and 500 moles per mole.
• the gaseous effluent treated in the hydrolysis-hydrogenation reactor 2 is then extracted and led via line 7 to a heat exchanger 8, for example an air cooler, of to cool the treated gas.
• the treated and cooled gas is transferred via line 9 into a liquid / gas separator 10.
• the liquid condensation water is recovered at the bottom of the separator 10, whereas the gas depleted in H 2 0 and containing the H 2 S is fed through the line 1 1 to a processing unit 1 2 which can be for example an H 2 S trapping unit or an H 2 S conversion unit which performs for example the oxidation of the H 2 S H 2 S to form elemental sulfur:
• the two hydrogenation and hydrolysis-hydrogenation reactions of the feedstock to be treated can be carried out in the same reactor comprising a first bed of hydrogenation catalysts and a second bed of hydrolysis-hydrogenation catalyst, the beds being arranged relative to each other in the reactor so that the gaseous feedstock to be treated meets the hydrogenation catalyst bed before the hydrolysis-hydrogenation catalyst bed, as shown in FIG.
• the second embodiment involves a single reactor 1 in which the hydrogenation and catalytic hydrolysis-hydrogenation reactions are carried out.
• the reactor comprises two beds of catalysts 13 and 14 respectively of hydrogenation and hydrolysis-hydrogenation. These two beds can be separated from one another by an internal space or on the contrary be consecutive without any intermediate space.
• the catalyst beds 1 3 and 14 are arranged in the reactor 1 so that the feedstock to be treated first encounters the catalytic hydrogenation bed 1 3 and then the catalytic hydrolysis-hydrogenation bed.
• an internal space separates the catalytic beds 1 3 and 14, in order to position in this space of an injection point a supplement of water necessary for the hydrolysis-hydrogenation reaction via line 6.
• the process according to the invention implements for steps a) and b) catalysts which have identical formulations which are arranged in two different reactors (according to FIG. 1) or in one and the same reactor (according to Figure 2).
• the gaseous effluent after the catalytic hydrolysis-hydrogenation step is discharged from reactor 1 and sent via line 5 into a heat exchanger 8 and then into a separator tank 10 via the line 9.
• the separator tank 10 is extracted in the bottom condensing water and at the top a charged gas H 2 S which is transferred to a trapping unit or conversion of H 2 S 12.
• the third embodiment of the method according to the invention is represented in FIG. 3 and differs essentially from the embodiments of FIGS. 1 and 2 in that it comprises a prior gas / liquid separation step performed on the gas to be treated. It is indeed advantageous to essentially remove excess water and / or possibly liquid organic compounds dissolved or not in the gas phase in order to reduce the volume of charge to be treated, while retaining an excess of water to achieve the hydrolysis-hydrogenation reaction.
• the gas to be treated which is generally hot, is sent to a heat exchanger 21 via line 20 where it is cooled, and then sent via line 22 to a separating balloon 23.
• a heat exchanger 21 via line 20 where it is cooled, and then sent via line 22 to a separating balloon 23.
• two phases are separated, namely a gas phase at the head and a liquid phase in the bottom which contains the water of the charge.
• the gas separated from this liquid and possibly a portion of the dissolved water from the separator tank 23 is sent through line 25 into a compressor 26 to be compressed.
• the compressed gas eventually undergoes, as shown in FIG. 3, a heating step through the optional heat exchanger 28 which, when present, is supplied with a hot fluid.
• This hot fluid is, preferably and according to the example of Figure 3, the hot gaseous effluent from the reaction zone 32 of hydrogenation and hydrolysis-hydrogenation.
• the preheated compressed gas may optionally be brought to the operating temperature by means of an optional heating unit 30, for example an exchanger, before being introduced into the reaction zone 32 where the hydrogenation reactions are carried out. hydrolysis-hydrogenation according to the process of the invention.
• the hot effluent from the reaction zone 32 is discharged via line 33 and introduced into the heat exchanger 28 to heat the gas to be treated.
• the treated gas rich in H 2 S may optionally be sent via line 34 into a second optional condenser 35, for example an air cooler and / or optionally into a heat exchanger 36 which is also optional.
• This cooling makes it possible to regulate the flow temperature to a temperature compatible with possible downstream treatments.
• the cooled stream can in particular be treated in a unit (not shown) for trapping H 2 S or for converting H 2 S to elemental sulfur. Examples
• gaseous feed A which corresponds to an effluent from a carbon black production unit and comprises sulfur and nitrogen compounds (COS, CS 2 and HCN) and acetylene.
• the gaseous feedstock to be treated therefore contains a not insignificant quantity of acetylene at a level of 0.3% by volume.
• Step a) Charge A described in Table 1 is first sent to a first reactor according to step a) of the invention.
• the hydrogenation catalyst used in step a) consists of 0.28% by weight of Pd on a support consisting of gamma-alumina agglomerated in the form of beads of 1.7 mm in diameter.
• Step a) is carried out under the following operating conditions:
• composition of the effluent from step a) is analyzed by gas chromatography after 48 hours of operation.
• the composition of the effluent from step a) is given in Table 2.
• the pretreatment of the gas in the charge by hydrogenation thus makes it possible to convert acetylene into ethane and consequently to bring the acetylene content to a value of less than 0.01% by volume.
• the effluent from step a) is then processed in a second reactor (step b) of the invention).
• the catalyst used in step b) has the following composition (expressed with respect to the total weight of the catalyst): 2.5% by weight of nickel oxide (NiO), 9.0% by weight of molybdenum trioxide (MoO 3 ) and 88.5% by weight of titanium oxide.
• the analyzes indicate that the preliminary hydrogenation step in order to saturate the unsaturated organic compounds makes it possible to preserve the catalytic performances of the catalyst, in particular the hydrolysis-hydrogenation activity with respect to the carbon disulphides.
• step b) The same charge A whose composition was given in Table 1 is treated in a hydrogenation step under the same conditions as Example 1.
• the effluent from step a) after 48 hours of operation is then treated in a second reactor (step b) of the invention).
• the catalyst used in step b) consists of 3% by weight of cobalt oxide, 14% by weight of molybdenum oxide, supported on gamma alumina.
• the hydrolysis-hydrogenation catalyst used therefore has a molar ratio (Co / Mo) equal to 0.4.
• Step b) is carried out under the following operating conditions:
• the H 2 0 content in the effluent from step a) (see Table 2) is 45% by volume, it is not necessary to add water to the effluent before treating it according to step b).
• composition of the effluent from step b) is given in Table 4.
• the same gaseous feed A is first sent to a first hydrogenation reactor for unsaturates according to step a) of the invention, under the same conditions as those of the example 1.
• step b) The effluent from step a) is then directed to a second reactor (step b) of the invention).
• the catalyst used in step b) consists of 0.65% by weight of cobalt oxide, 14% by weight of molybdenum oxide, supported on gamma alumina.
• the hydrolysis-hydrogenation catalyst used therefore has a molar ratio (Co / Mo) equal to 0.09.
• Step b) is carried out under the following operating conditions:
• the H 2 0 content in the effluent from step a) (see Table 2) is 45% by volume, it is not necessary to add water to the effluent before treating it according to step b).
• composition of the effluent from step b) is given in Table 5.
• Table 5 Composition of the effluent of the hydrolysis-hydrogenation step A lowering of the content of CS 2 which is only of the order of 69% is obtained.
• Example 4 (according to the invention)
• step b) The effluent from step a) is then directed to a second reactor (step b) of the invention).
• the catalyst used in step b) consists of 3.9% by weight of nickel oxide, 28% by weight of tungsten oxide, supported on gamma alumina.
• the hydrolysis-hydrogenation catalyst used therefore has a molar ratio (Ni / W) equal to 0.43.
• Step b) is carried out under the following operating conditions:
• the H 2 0 content in the effluent from step a) (see Table 2) is 45% by volume, it is not necessary to add water to the effluent before treating it according to step b).
• composition of the effluent from step b) is given in Table 6.
• Table 6 Composition of the effluent of the hydrolysis-hydrogenation step A reduction in the CS 2 content of about 90% is obtained.
• Step a) is carried out under the operating conditions and with the catalyst of step a) of Example 1.
• step b) The effluent from step a) is then directed to a second reactor (step b) of the invention).
• the catalyst used in step b) consists of 2.5% by weight of nickel oxide, 9.0% by weight of molybdenum oxide, supported on gamma alumina.
• the hydrolysis-hydrogenation catalyst used therefore has a molar ratio (Ni / Mo) equal to 0.53.
• Step b) is carried out under the following operating conditions:
• the content of H 2 0 in the effluent resulting from stage a) (see Table 2) is 45% by volume, it is not necessary to add water to the effluent before treating it according to step b).
• the composition of the effluent from step b) is given in Table 7.
• Step a) is carried out under the operating conditions and with the catalyst of step a) of Example 1.
• step b) The effluent from step a) is then directed to a second reactor according to step b) of the invention.
• the catalyst used in step b) consists of 17% by weight of cobalt oxide, 14% by weight of molybdenum oxide, supported on a gamma-alumina. During the preparation of this catalyst, all the cobalt and molybdenum were impregnated in a single impregnation step on the support.
• the hydrolysis-hydrogenation catalyst used has a molar ratio (Co / Mo) equal to 2.3.
• Step b) is carried out under the following operating conditions:
• the H 2 0 content in the effluent from step a) (see Table 2) is 45% by volume, it is not necessary to add water to the effluent before treating it according to step b).
• composition of the effluent from step b) is given in Table 7.
• Table 8 Composition of the effluent of the hydrolysis-hydrogenation step
• CS 2 contents of the effluents obtained at the end of the treatment with the catalysts according to the invention are also lower than in the case of Example 1 (comparative) which implements a NiMo catalyst. / Ti0 2 .

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