WO1992020621A1 - Catalyseur et procede d'extraction de composes de soufre et d'oxydes azotes a partir de courants de fluides - Google Patents

Catalyseur et procede d'extraction de composes de soufre et d'oxydes azotes a partir de courants de fluides Download PDF

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Publication number
WO1992020621A1
WO1992020621A1 PCT/CA1991/000160 CA9100160W WO9220621A1 WO 1992020621 A1 WO1992020621 A1 WO 1992020621A1 CA 9100160 W CA9100160 W CA 9100160W WO 9220621 A1 WO9220621 A1 WO 9220621A1
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Prior art keywords
sulphur
support
oxygen
catalyst
oxide
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PCT/CA1991/000160
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English (en)
Inventor
Kalabeerappa N. Mahadev
Jamsheed Phiroze Irani
Harry E. Gunning
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Budra Research Ltd.
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Priority to PCT/CA1991/000160 priority Critical patent/WO1992020621A1/fr
Priority to CA002087265A priority patent/CA2087265C/fr
Publication of WO1992020621A1 publication Critical patent/WO1992020621A1/fr

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    • 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
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
    • B01J27/04—Sulfides
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8603—Removing sulfur compounds
    • B01D53/8612—Hydrogen sulfide
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8637—Simultaneously removing sulfur oxides and nitrogen oxides
    • 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
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
    • B01J27/057—Selenium or tellurium; Compounds thereof
    • B01J27/0573—Selenium; Compounds thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/02—Preparation of sulfur; Purification
    • C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
    • C01B17/0404—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process
    • C01B17/046—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process without intermediate formation of sulfur dioxide
    • C01B17/0469—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process without intermediate formation of sulfur dioxide at least one catalyst bed operating below the dew-point of sulfur
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/02—Preparation of sulfur; Purification
    • C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
    • C01B17/0473—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by reaction of sulfur dioxide or sulfur trioxide containing gases with reducing agents other than hydrogen sulfide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/24—Nitric oxide (NO)
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

Definitions

  • This invention comprises a novel method and catalyst for effecting such removal and the subsequent treatment of such sulphur compounds to produce elemental sulphur. More particularly this invention is applicable to the removal of hydrogen sulphide and other sulphur compounds from sour natural gas, and other fluid streams, and the conversion of the sulphur therein to elemental sulphur.
  • the invention may be used to remove certain oxygen compounds from gas streams, and particularly to remove sulphur dioxide, sulphur trioxide, nitrogen trioxide, nitrogen peroxide, nitrogen pentoxide and carbon dioxide from flue gases.
  • Sulphur compounds are often considered to be undesirable compounds in gas mixtures and other fluid streams.
  • the most common example of this is that of natural gas containing hydrogen sulphide.
  • Natural gas may also contain as undesirable sulphur compounds, quantities of carbonyl sulphide, carbon disulphide, mono and dialkyl sulphides, alkyl-type disulphides and thiophenes.
  • the Claus process is a complex multi-stage system involving the absorption of the hydrogen sulphide in an amine absorbent, flashing off H 2 S from the amine, followed by the burning of part of the hydrogen sulphide to sulfur dioxide, and subsequently reacting the hydrogen sulphide with the sulfur dioxide to produce sulphur as the final product as elemental sulphur.
  • Flue gases generally include appreciable quantities of oxides of sulphur, nitrogen peroxide and carbon dioxide. It would be desireable to have a process which effectively removes such compounds from flue gas, and allows for their separation and subsequent utilization.
  • a further object of the invention is to remove sulphur dioxide, nitrogen trioxide, nitrogen peroxide nitrogen pentoxide and carbon dioxide, separately or collectively from a gas stream, and then to convert the sulphur dioxide to sulphur, convert the nitrogen peroxide and other oxides to nitric oxide, and separately release the carbon dioxide, nitric oxide and sulphur so produced for subsequent utilization.
  • this invention comprises a regeneratable catalytic composition
  • a regeneratable catalytic composition comprising a support having associated therewith a non-gaseous, non- fluid substance capable of retaining and providing reactive oxygen for reaction with oxidizable substances brought into contact with such composition, and thereafter capable of being replenished with reactive oxygen y exposure to a source of oxygen.
  • the inver?- ion may be characterized as a "regeneratable solid peroxi ⁇ e" - type of composition, and includes methods by which such composition may be employed
  • this invention comprises a specially prepared bed for absorbing sulphur compounds, and particularly hydrogen sulphide or oxides of sulphur from a fluid stream and subsequently decomposing such compounds into elemental sulphur.
  • This same bed may be used to absorb oxides of nitrogen, and particuarly nitrogen peroxide but excluding nitrous oxide, and absorb as well carbon dioxide from a gas stream for subsequent separate recovery.
  • a suitable bed for treating non-oxide compounds of sulphur comprises a support adapted to accommodate or absorb such non-oxide sulphur compounds therein, and particularly hydrogen sulphide, which support contains an alkali metal sulphide or selenide together with a sulphide or sulphides, (or selenide/s) of metals showing polyvalent and/or amphoteric character deposited therein, and has been rendered thereby capable of providing internally available "reactive oxygen", e.g. having peroxide-like characteristics, after exposure to a source of oxygen.
  • "and/or" in the above discussion, and throughout this disclosure is to be taken in its non- exclusory sense.
  • a mixture of both amphoteric and polyvalent compounds may be used in place of either alone, and a metal which is both amphoteric and polyvalent is intended to be included by this expression.
  • reactive oxygen is intended to refer to oxygen in an elevated energy state whereby the oxygen is available to react with the non-sulphur component of the compounds being treated in some cases even at ambient temperatures so as to release sulphur.
  • Amphoteric metals are those metals which show a capacity to react both with acids and bases.
  • amphoteric or polyvalent metal sulphides or selenides suitable for use in this invention include, amongst others, sulphides or selenides of metals from the group consisting of zinc, manganese, iron, copper, cobalt, aluminum, vanadium, molybdenum, tin and nickel as well as mixtures thereof.
  • alkali metals suitable for use in this invention include lithium, potassium, sodium, rubidium and cesium, as well as mixtures thereof.
  • a bed so constituted and suitably conditioned according to this invention is also adapted to remove and decompose sulphur compounds such as carbonyl sulphide, carbon disulphide, mono and dialkyl sulphides, alkyl-type disulphides, and thiophenes from a gas or liquid stream by contacting such a stream with the aforesaid bed, at ambient temperatures.
  • This same bed is capable of absorbing oxygen-containing compounds to provide reactive oxygen.
  • Suitable compounds for this effect are sulphur dioxide, sulphur trioxide and nitrogen oxides, including nitrogen trioxide, nitrogen peroxide and nitrogen pentoxide but excluding nitrous oxide, i.e. the "higher" oxides of nitrogen.
  • One method of preparing the bed is by:
  • This invention further comprises the production of elemental sulphur by the method of exposing, at a temperature below the vaporization point of sulphur, a gas stream containing non-oxide compounds of sulphur, and particularly for example hydrogen sulphide, to the oxygenated bed and then regenerating the bed.
  • the bed is regenerated by first applying heat at a predetermined elevated temperature or temperatures (such as in the range of 250°C to 600°C) bed in the presence of a substantially non-reactive sweep gas. This will drive off any residues of the oxidized non-sulphur component of the sulphur compound, this being in the case of hydrogen sulphide water, and elemental sulphur thus purging the bed of these substances.
  • the regeneration process is then completed and the bed reconditioned by exposure of such bed to an unreactive sweep gas containing a source of oxygen.
  • a source of oxygen may also be provided during the initial purging step either as an alternative to subsequent treatment with oxygen, or in addition.
  • the amount of oxygen provided with the sweep gas in the final step may range from a stoichiometric amount necessary to oxidize the sulphur compound to be subsequently treated and release elemental sulphur, up to a concentration of about 25%, although this is not necessarily limiting in all cases. In certain cases excess oxygen and highly oxidizing agents such as hydrogen peroxide must be avoided to prevent damage to the bed.
  • This invention further comprises the method by which the oxides of sulphur, particularly sulphur dioxide and the oxides of nitrogen, particularly nitrogen peroxide but excluding nitrous oxide, are removed from a gas stream.
  • a reducing gas such as to a stream of hydrogen sulphide, whereby the absorbed sulphur dioxide and hydrogen sulphide are converted to water and elemental sulphur, and the nitrogen peroxide and other nitrogen oxides are converted to nitric oxide.
  • the bed containing the above referenced activating ingredients when depleted of internally available reactive oxygen, is capable of absorbing at ambient temperatures quantities of carbon dioxide.
  • the absorption of carbon dioxide can be carried-out either separately or in conjunction with the absorption of the other referenced oxides. Once carbon dioxide has been absorbed, it can be released and recovered by heating the bed.
  • Figure 1 is a graph showing the effect of temperature on the rate of desorption of hydrogen sulphide from a series of sample catalytic beds which have been saturated with hydrogen sulphide.
  • Figure 2 shows the capacity of a bed according to the invention to become loaded with hydrogen sulphide and sulphur dioxide as a function of pressure.
  • the active catalyst within the bed that provides reactive oxygen is believed to be characterized by a chemical having as its constituents a complex containing the combination of an amphoteric and/or polyvalent metal (hereinafter referred to as the "metal"), an alkali metal, (hereinafter referred to as the "alkali”), sulphur or selenium and the capacity to retain an active oxygen- containing moiety that contains an available reactive oxygen group.
  • This complex should preferably be formed within a microporous support having a relatively high surface area and a microporosity adapted to receive the sulphur or oxide compound to be decomposed.
  • Alumina is considered a preferred support because of its high surface area.
  • alkali metal incorporated into the support to form the active complex will react with alumina to form an alkali alu inate and facilitate bonding of the active complex to the carrier.
  • Alumina may thereby provide an etchable substrate upon which active sites may be more readily formed.
  • the catalyst is capable of decomposing a small portion of absorbed hydrogen sulphide without the addition of oxygen during the decomposition heating phase.
  • the activity of the catalyst under such conditions declines rapidly. It is believed that the catalyst is intrinsically capable of supplying small amounts of oxygen, but that this capacity is rapidly depleted. This belief is supported by the observation that exposure of the catalyst to a reducing atmosphere causes catalytic decompositional activity to drop to virtually zero.
  • a bed prepared in accordance with the invention, will absorb not only molecular oxygen, but also sulphur dioxide, sulphur trioxide and nitrogen oxides, excluding nitric oxide. All of these compounds are capable of producing the reactive oxygen which is characteristic of the invention.
  • This ability of the catalyst to become oxygen- activated with such compounds allows a catalytic bed, prepared in accordance with the invention, to be used to absorb such compounds from flue gas.
  • the bed once saturated, may then be purged of such compounds by exposure to hydrogen sulphide, followed by heating in the presence of a sweep gas.
  • hydrogen sulphide In the case of sulphur dioxide, this compound is decomposed into water and elemental sulphur.
  • Catalytic beds were prepared by two alternate methods.
  • the first method commenced by dissolving a predetermined amount of the alkali sulphide (sodium or potassium) in water sufficient to form the ultimate desired loading on the support and optionally boiling the solution.
  • a molar equivalent amount of an amphoteric and/or polyvalent metal sulphide was added and the solution was boiled again until the volume was reduced to a point short of saturation.
  • the support generally in the form of Alcoa alumina spheres, #S-100 which had been dried by being heated to 250°C for 4 hours was added to the hot solution and mixed until all the solution was absorbed into the support.
  • the partially prepared catalytic bed was then dried (using a nitrogen gas flow at 400°C) and cooled.
  • the catalytic bed was then sulphided by exposure to a stream of 10% hydrogen sulphide in nitrogen or methane at ambient conditions until hydrogen sulphide was detected in the effluent and for at least one hour thereafter. It was then purged of excess sulphur by heating in a nitrogen gas flow at 400-500°C for a period of 0.5 to 1.0 hours to drive off free sulphur.
  • the partially prepared catalytic bed can also be sulphided by exposure first to a stream of 10% hydrogen sulphide in nitrogen or methane at 400°-500°C for 4 hours and then to a stream of nitrogen or methane at 400°-500°c to remove any excess sulphur.
  • a second method of preparing the catalytic bed was as follows. A sulphate, chloride or nitrate of a polyvalent and/or amphoteric metal was dissolved in an aqueous solution. The mixture was then heated to ensure rapid dissolution. (This, as above, is considered an optional step.)
  • the solution was then impregnated on a previously dried alumina support (Alcoa S-100, 1/4 in. spheres) and the impregnated support dried.
  • a molar equivalent or greater amount of an alkali metal sulphide was then prepared in an aqueous solution and impregnated on the support. Again, heating was optionally employed to effect rapid dissolution.
  • the impregnated support was then heated to a temperature of 125°C for a period of 2 hours in order to fix the active ingredients within the support. This was followed by a washing of the impregnated support with water until all available alkali sulphate, chloride or nitrate had been flushed from the support. The impregnated support was then dried at 125°C.
  • amphoteric and/or polyvalent metals in the form of sulphates, chlorides or nitrates and, it is believed, may be carried-out with any soluble salts of such metals including zinc, iron, vanadium, copper, nickel, molybdenum, aluminum and manganese. It is believed that an active catalyst would be produced when these methods are carried out with all amphoteric and/or polyvalent metals. It is further believed that these methods would be effective in producing an active catalyst whether sulphide or selenide salts of all amphoteric and/or polyvalent metals are used. Where less soluble compounds are employed, it may be appropriate to employ a basic aqueous solution in order to facilitate dissolution. A sufficiently basic solution can be created by adding alkali hydroxide to the solution of the amphoteric and/or polyvalent metal salt and boiling this mixture.
  • selenium may be substituted for the sulphur in the alkali sulphide and still produce an active catalyst. Based on sample tests, a satisfactory standard of performance for the catalyst in terms of both absorptive and decomposing capacity can be obtained with an approximate 1:1 molar ratio between the metal and alkali components, and a similar 1:1 molar ratio where an alkali hydroxide is additionally employed.
  • Absorptive capacity for hydrogen sulphide is maximized for various metal sulphides at different levels of impregnation of the support. For example, this occurs between the 0.5% to 2.5% loading (by weight) range for a catalyst incorporating a zinc sulphide/sodium sulphide mixture deposited by Method 1 on the Alcoa carrier (S-100 spheres) .
  • the bed may be activated in conjunction with the sulphiding steps by exposing it, as an optional first step, at ambient or higher temperatures to an unreactive gas containing hydrogen sulphide, followed by heat treatment in an unreactive sweep gas at a temperature of 250°C-700°C containing an amount of oxygen as referenced above. Alternately, after treatment with the sweep gas at elevated temperatures the bed may be exposed to oxygen at temperatures down to ambient conditions.
  • Unreactive is used here and throughout in the sense of a gas that does not substantially react in this system. It is most desirable that the activating gas streams not contain appreciable amounts of compounds or elements, such as hydrogen, which will have a major reductive effect on the activity of the catalyst. It is also important for the treatment- of non-oxide compounds of sulphur that the catalyst be exposed by the conclusion of the conditioning process to suf icient oxygen to ensure that reactive oxygen will be available within the catalyst to render it activated.
  • the source of oxygen may be either atmospheric or molecular oxygen, or may be a compound such as sulphur dioxide or nitrogen peroxide. All three of these sources have been found to produce, within the catalytic bed, the reactive oxygen which is a characteristic of the invention.
  • the length of exposure was either that required to produce an indication of hydrogen sulphide "breakthrough" at the exit end (as measured by the blackening of standardized lead acetate paper, or other standard methods) , or some lesser period of time.
  • a run to breakthrough was said to have saturated the bed.
  • a run carried to a point short of saturation was designated as a "partial run”.
  • the catalytic bed in its tube was then weighed to determine either the saturation loading of the bed, or the partial loading of the bed, in terms of its absorption of hydrogen sulphide.
  • the catalytic beds utilizing molecular sieves or alumina supports showed a capacity in the foregoing sweetening phase of maintaining the hydrogen sulphide level in the out-flowing stream below the measurable threshold Vis, 1 part per million prior to breakthrough.
  • the catalytic bed in its reaction tube was then put through the purging phase by exposing the bed to an unreactive sweep gas (nitrogen or methane) at a specific temperature above the vapourization point for elemental sulphur for a period of time.
  • the bed may then be reactivated by exposing it to a source of oxygen. This may be done, for example, by utilizing a sweep ga ⁇ containing" oxygen at levels of 0.01 to 25%.
  • Oxyge- 1 may also be supplied in the form of sulphur dioxide o_. nitrogen peroxide. Alternately, reactivation by exposure to a source of oxygen may be effected separately, after the purging phase is complete.
  • the sweep gas exiting the catalytic bed was caused to pass through a portion of the reaction tube that was maintained at room temperature.
  • a portion of the reaction tube that was maintained at room temperature.
  • sulphur consistently condensed on the inside walls of a cooler, exit portion of the reaction tube in a condensation zone.
  • Sample tests with glasswool placed downstream of such deposits indicated that further sulphur could not be collected by condensation from the cooled exiting gas stream beyond the condensation zone.
  • Oxygen may be supplied to the bed either in its molecular form, or in a compound such as sulphur dioxide or nitrogen peroxide.
  • Sulphur dioxide has been found to produce a much higher deposition of reactive oxygen within the catalyst.
  • the use of sulphur dioxide also increases the absorptive capacity of the bed with respect to hydrogen sulphide.
  • the exposure of alumina to sulphur dioxide would normally be expected to result in the production of aluminum sulphite. If oxygen is present, as well, then aluminum sulphate will likely form.
  • alumina has been treated by the deposition therein of the combination of sulphide or selenide salts of amphoteric or polyvalent metals combined with sulphite or selenide salts of alkali metals, the tendency of the alumina to form aluminum sulphite or sulphate is believed to be significantly reduced. From the foregoing procedures calculations were made to determine the extent to which the hydrogen sulphide was converted to sulphur. The quantity of hydrogen sulphide absorbed in the catalyst bed was calculated based both on the gas flow rate, and on the gain in weight of the bed and tube during the sweetening phase. The quantity of sulphur produced was obtained from the heat-vaporization procedure.
  • the actual quantity of hydrogen sulphide decomposed was also determined by the difference between the volume of hydrogen sulphide absorbed by the catalyst, and the volume of hydrogen sulphide collected by a gas bag during the regeneration. Of these methods, the mass of sulphur vaporized off the interior of the reaction tube was taken as the more reliable measure of the minimum decomposition that had occurred.
  • the procedure of utilizing the bed first to absorb hydrogen sulphide followed by reactivation with sulphur dioxide may be reversed or shifted in order.
  • the bed is first purged of sulphur dioxide by exposure to hydrogen sulphide, then purged of sulphur by heating in the presence of an oxygen-free sweep gas. So prepared, the bed will then readily absorb sulphur dioxide to the limit of saturation. Once the bed has been saturated with sulphur dioxide, it may be again exposed to hydrogen sulphide to purge it of the sulphur and water that is thereby formed.
  • the bed will similarly absorb sulphur trioxide, which can be converted to produce sulphur by the same steps.
  • sulphur dioxide when used as the source for oxygen, it is relatively tenaciously contained within alumina-type supports. This enables an activated bed to be prepared in one location, and then transported to another. Similarly where the bed is only partially saturated with hydrogen sulphide in the sweetening cycle, the bed material is readily transportable.
  • the bed suitably depleted of oxygen has _... affinity to absorb not only the oxides of sulphur, but also nitrogen peroxide and similar higher oxides (but not nitrous oxide) , and carbon dioxide. Further, the bed has the capability of absorbing all of these classes of oxides simultaneously.
  • the source of oxygen may also be nitrogen peroxide. This is a component often found in the products of combustion and in flue gases. When nitrogen peroxide is used as the source of oxygen, subsequent exposure of the bed to hydrogen sulphide results in the production of elemental sulphur, water and nitric oxide - NO. When the catalyst is purged of sulphur by heating, the nitric oxide evolves. This nitric oxide can then be trapped downstream, after air- oxidation to nitrogen peroxide and then used for other chemical reactions, such as the preparaton of nitrates.
  • the advantage of this cycle is that the bed can be employed to first absorb the nitrogen peroxide, separating it from a flue gas stream for subsequent recovery.
  • the catalyst can be activated by mixtures of N0 2 and S0 2 in an air stream, at ambient temperatures.
  • this catalyst is treated with a stream of H S and subsequently heated, sulphur, water and nitric oxide all distill off.
  • Tests based on the activation of a 2(Na S)/ZnS form of catalyst deposited in S-100 Alcoa spheres show a capacity for such a bed to absorb up to 6% by weight of sulphur dioxide, 9.1% by weight of nitrogen peroxide and 6% of carbon dioxide, simultaneously.
  • the gas stream used for this test contained 10-12% of C0 ; 4-6% of 0 2 ; 1000-2000 ppm of S0 2 and 100-400 ppm of N0 2 . These ratios are typical for a flue gas.
  • the absorption capacities for each of these components do not appear to be substantially cross- related.
  • the catalyst will retain 60 kg of C0 2 from the stream at saturation, and continues to absorb S0 2 until 60 kg of this compound has been removed from the stream. The absorption of N0 2 then continues until 91 kg of this oxide had been recovered. To prevent any S0 2 from escaping under these conditions, an additional catalyst bed would be placed downstream to strip out any S0 2 leaving the first catalyst chamber by desorption.
  • this exposed catalyst When this exposed catalyst is treated with hydrogen sulphide, the oxides of sulphur and nitrogen react with the absorbed hydrogen sulphide, and convert the sulphur oxides to sulphur and water. After reaction is complete, the catalyst contains elemental sulphur, nitric oxide, carbon dioxide and water. Heat treatment, at 400°C, drives off the sulphur, nitric oxide, and carbon dioxide. Each may be separately recovered downstream. After the absorption stage is completed and the absorbed components have been treated with hydrogen sulphide, the spent catalyst is heated. Carbon dioxide C0 2 will be the first substance to desorb, and can be trapped by many standard methods. As the temperature rises nitric oxide, NO will next come off, which substance can be converted in air to N0 2 .
  • Figure 1 shows this effect in which a blank Alcoa (S-100) alumina support is compared with catalysts prepared by Method 1 with Zinc and Potassium sulphide; Zinc, Copper and Potassium sulphides, and Copper and Potassium sulphides all on the same type of S-100 support. All beds were loaded to saturation and then treated in the sweetening phase for 90 minutes at various temperatures.
  • Figure 1 shows the percentage of the hydrogen sulphide evolved, as a function of temperature after heating for 90 minutes at various temperatures.
  • Table 1 summarizes the data depicted in Figure 1 and adds the accumulated percent decomposition obtained both after the 90 minute heating at a constant temperature and after the final regeneration at 400°C. These percentages are based in both cases on conversion of sulphur, being the mass of sulphur vaporized divided by the mass of sulphur available in the quantity of hydrogen sulphide originally absorbed.
  • the catalyst when used in association with microporous supports such as alumina or zeolite, rapidly absorbs hydrogen sulphide. It may be that the rapidity with which the hydrogen sulphide is absorbed permits the catalytic bed, at suitable flow rates, to saturate progressively when exposed to a sour gas stream. If the sweetening phase is terminated with only a portion of the bed exposed (and saturated) with hydrogen sulphide, then, as heat is applied to the bed in the presence of a sweep gas absorbed hydrogen sulphide that may be desorbed is swept into a region of the bed containing unexposed catalyst. Consequently, a bed that is partially loaded to saturation along only a portion of its length would be capable, in the separation phase, it is believed, of exposing virtually all of the hydrogen sulphide to chemical-absorption leading to decomposition.
  • Table 3 lists combinations of further ingredients all found to produce non-quantified but definite amounts of elemental sulphur upon the consecutive exposure of the catalytic bed to a 10% hydrogen sulphide/90% nitrogen gas stream at ambient temperature 18°C) , followed by regeneration of the catalyst at temperatures ranging from 350-400°C as previously described. All runs were carried out using as a support the Alcoa alumina carrier No. S- 100. All of the samples listed in Table 3 were prepared from sulphides in accordance with the procedure of Method 1.
  • the column entitled “Absorptive Capacity” indicates the percentage ratio of mass of sulphur absorbed to the mass of catalyst, at the point where the catalyst bed ceased to fully absorb further hydrogen sulphide (as tested by the darkening of lead acetate paper at the column exit) .
  • Iron & Zinc Sodium Sulphide Iron, Copper & Sodium sulphide and Zinc Sodium hydroxide 2.2
  • a two-to-one molar ratio of sodium sulphide to zinc sulphide was deposited on S-100 Alcoa Alumina Spheres.
  • the amount of such components deposited was set, for two different samples, at 1% and 2% by weight of the final loaded support.
  • One hundred grams each of the two classes of catalyzed support, along with pure, crushed S-100 spheres were then progressively loaded with sulphur dioxide at room temperature by exposure to a stream of 18% concentration by volume of S0 2 in nitrogen; and then exposed to a stream of methane containing 10% by volume of hydrogen sulphide.
  • the amounts of sulphur-equivalent absorbed and then converted to sulphur are shown in Table 5 where a comparison to a blank alumina support is also provided.
  • S0 2 and H 2 S loading figures are in grams of Sulphur per 100 g of catalyst.
  • Table 7 shows sulphur conversion ratios that are on the same order as those of Table 5. Further, the increased absorptive capacity of the catalyzed support under pressure is also shown.
  • the activation stage did not produce activated sulphur sites at all possible locations within the micro ⁇ porous support, to the exclusion of sites capable of absorbing hydrogen sulphide. Consequently, during the process of exposing hydrogen sulphide to the catalyst to effect dissociation, considerable quantities of hydrogen sulphide became absorbed without becoming dissociated.
  • the catalyst was cyclically exposed to the steps of being saturated with hydrogen sulphide, then regenerated by purging it of water and elemental sulphur (at 350°C) , and then reactivated by exposure to air (at 200°C) .
  • activation of the catalyst is effected by exposing the micro-porous support to sulphur dioxide. It is believed that this procedure is more efficient in forming active sites that are capable of dissociating hydrogen sulphide. This greatly reduces the amount of hydrogen sulphide that is absorbed and then released without being dissociated. When the catalyst has been activated by sulphur dioxide virtually no hydrogen sulphide appears in the regeneration phase.
  • the sulphur dioxide activation process relies upon the formation of a highly reactive sulphite within the micro-porous support. To form this sulphite, a metal must be present within the support. Water must also be present to allow the formation of the sulphite and the subsequent dissociation of hydrogen sulphide.
  • the sulphur dioxide activated process is capable of operating with a pure alumina support.
  • the deposition within this support of an amphoteric or polyvalent metal sulphide, together with an alkali sulphide, enhances both the system's capacity to remove hydrogen sulphide from a gas stream, and its efficiency in converting hydrogen sulphide into sulphur.
  • the catalyst will be active in decomposing organic-sulphur compounds such as carbonyl sulphide, carbon disulphide, mono and dialkyl sulphides, alkyl-type disulphides and thiophene. It is also suitable for removing all of the foregoing from a mixture of more complex natural gas components in gaseous or liquid phase, such as from butane or propane, and including, generally, natural gas liquids.
  • the principal support used in testing has been alumina in the form of Alcoa 1/4 or 3/4 inch spheres (#S- 100) .
  • Other supports tested for absorptive capacity include alumina in the form of Norton 5/16" rings (#6573), Norton spheres (#6576) ; CIL Prox-Svers non-uniform spheres, Davison Chemical molecular sieves (type 13x, 4-8 mesh beads) , silica and char.
  • the Alcoa support was chosen as the preferred carrier due to its high absorptive capacity, which was due, in turn, to its large surface area (325m /gm) .
  • the Alcoa support referenced is essentially alumina that is reported as being in the gamma and amorphous form. It is not believed that the type of crystalline form in which the alumina may be found is of significance to the dissociative capacity of the catalyst.
  • Aluminum-containing supports inherently are capable of providing active centres necessary to support the activity of the catalyst. Such supports also provide an etchable base upon which actively catalytic sites are thought to be more likely to form.
  • the capacity of the support to fully absorb hydrogen sulphide and/or other sulphur compounds is an important feature when it is desired to remove all significant traces of such compounds from a gas stream. This characteristic is believed to be dominated by the support itself.
  • the efficiency of absorption by the carrier is less critical. In such cases supports may be used that do not effect 100% absorption of hydrogen sulphide prior to saturation.
  • metal and alkali sulphides are formed within the alumina of the alumina support, rather than just being deposited on the surface.
  • the prepared catalysts were run through at least 4 cycles of absorption and regeneration before quantified tests were carried out on them. These initial cycles were found appropriate to stabilize the catalyst and obtain relatively consistent results in subsequent tests. Generally, the activity of the catalyst in terms of its decomposing capacity increased following these preliminary recyclings. No significant decline or loss of activity in dissociative capacity of the catalyst has been found despite a number of consecutive absorption and regeneration cycles so long as replacement oxygen f.s available. The absorptive capacity of the catalyse has been shown to remain relatively unchanged through at least 30-40 cycles of absorption and regeneration.
  • the absorptive capacity of the catalyst (in terms of the ratio of the mass of hydrogen sulphide removed in the absorption stage to the mass of the catalyst) is relatively insensitive to the concentration of hydrogen sulphide in the gas stream for concentrations of hydrogen sulphide up to 10%. It rises, however, approximately linearly with total pressure, up to at least 500 psig. At modest flow rates, the rate of removal of hydrogen sulphide by absorption in the case of alumina carriers is relatively high, up to the point where the catalyst bed has been nearly totally saturated with hydrogen sulphide at ambient temperature and pressure. Some tests were done with a 3 minute residence time. Other tests were done with a 0.7 minute residence time.

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Abstract

L'invention se rapporte à un catalyseur pouvant être régénéré et susceptible de produire de l'oxygène réactif pour oxyder partiellement des composés contenant du soufre afin de produire du soufre. L'invention se rapporte aussi à un procédé servant à extraire des composés de soufre comprenant à la fois des oxydes de soufre et de l'acide sulfurique d'un courant de fluide et à décomposer de tels composés pour produire du soufre. Du gaz naturel sulfureux peut être efficacement adouci selon ce procédé, et du soufre peut être ainsi produit. Le catalyseur est de préférence obtenu lorsqu'on imprègne un support de type mocroporeux, (par exemple l'alumine), de sulfure métallique alcalin et de sulfure(s) ou séléniure(s) de métaux du type polyvalent et/ou amphotère tels que Zn etc. Son activité est renforcée lorsqu'on l'expose à une source d'oxygène, telle que l'air, l'oxygène, le dioxyde de soufre ou le peroxyde d'azote ou analogue. On décrit aussi un procédé selon lequel du dioxyde de soufre peut être absorbé à partir d'un gaz de combustion et converti en soufre, alors que des oxydes supérieurs d'azote et du dioxyde de carbone sont absorbés pour être récupéres ultérieurement, à l'aide d'un catalyseur qui a été traité par une exposition antérieure à un gaz réducteur.
PCT/CA1991/000160 1991-05-13 1991-05-13 Catalyseur et procede d'extraction de composes de soufre et d'oxydes azotes a partir de courants de fluides WO1992020621A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/CA1991/000160 WO1992020621A1 (fr) 1991-05-13 1991-05-13 Catalyseur et procede d'extraction de composes de soufre et d'oxydes azotes a partir de courants de fluides
CA002087265A CA2087265C (fr) 1991-05-13 1991-05-13 Catalyseur et procede d'elimination de composes soufres et d'oxydes de liquides en circulation

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PCT/CA1991/000160 WO1992020621A1 (fr) 1991-05-13 1991-05-13 Catalyseur et procede d'extraction de composes de soufre et d'oxydes azotes a partir de courants de fluides

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1111080C (zh) * 2000-08-03 2003-06-11 上海复洁环境科技工程有限公司 活性氧净化处理有机废气和恶臭气体的方法及其装置
WO2004055135A1 (fr) * 2002-12-17 2004-07-01 Shell Internationale Research Maatschappij B.V. Processus d'oxydation selective catalytique de composes de soufre
CN102862962A (zh) * 2012-10-16 2013-01-09 中南大学 单质硒作为催化剂的应用

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105712301B (zh) * 2014-12-04 2017-10-27 中国石油化工股份有限公司 一种天然气中h2s转化为硫磺的工艺

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US3321274A (en) * 1963-12-13 1967-05-23 Shell Oil Co Process for reducing nitric oxide to nitrous oxide
GB1400365A (en) * 1972-06-29 1975-07-16 Rhone Progil Method of removing sulphur from a gas containing one or more compounds thereof
US4039613A (en) * 1973-10-29 1977-08-02 Agency Of Industrial Science & Technology Process for production of hydrogen and sulfur from hydrogen sulfide as raw material
EP0071983A2 (fr) * 1981-08-07 1983-02-16 Veg-Gasinstituut N.V. Procédé pour éliminer des composés de soufre contenus dans des gaz
US4438218A (en) * 1981-07-27 1984-03-20 Alberta Oil Sands Technology And Research Authority Catalyst for sulphur removal from hydrocarbons
EP0324091A2 (fr) * 1987-11-28 1989-07-19 Gastec N.V. Procédé d'élimination du sulfure d'hydrogène de gaz

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Publication number Priority date Publication date Assignee Title
US3321274A (en) * 1963-12-13 1967-05-23 Shell Oil Co Process for reducing nitric oxide to nitrous oxide
GB1400365A (en) * 1972-06-29 1975-07-16 Rhone Progil Method of removing sulphur from a gas containing one or more compounds thereof
US4039613A (en) * 1973-10-29 1977-08-02 Agency Of Industrial Science & Technology Process for production of hydrogen and sulfur from hydrogen sulfide as raw material
US4438218A (en) * 1981-07-27 1984-03-20 Alberta Oil Sands Technology And Research Authority Catalyst for sulphur removal from hydrocarbons
EP0071983A2 (fr) * 1981-08-07 1983-02-16 Veg-Gasinstituut N.V. Procédé pour éliminer des composés de soufre contenus dans des gaz
EP0324091A2 (fr) * 1987-11-28 1989-07-19 Gastec N.V. Procédé d'élimination du sulfure d'hydrogène de gaz

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1111080C (zh) * 2000-08-03 2003-06-11 上海复洁环境科技工程有限公司 活性氧净化处理有机废气和恶臭气体的方法及其装置
WO2004055135A1 (fr) * 2002-12-17 2004-07-01 Shell Internationale Research Maatschappij B.V. Processus d'oxydation selective catalytique de composes de soufre
EA007581B1 (ru) * 2002-12-17 2006-12-29 Шелл Интернэшнл Рисерч Маатсхаппий Б.В. Способ каталитического селективного окисления сернистых соединений
CN102862962A (zh) * 2012-10-16 2013-01-09 中南大学 单质硒作为催化剂的应用

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