Method and catalyst for oxidation of the sulfur catalytic method h2s contained in low concentrations in the gas

 

(57) Abstract:

The invention is intended for direct oxidation at sulfur catalytic method H2S contained in the gas in low concentrations. The gas containing H2S, is treated with a gas containing free oxygen, in contact with a catalyst for selective oxidation of N2S to sulfur. The gas contains free oxygen in an amount to provide a receipt molar ratio of O2:H2S from 0.05 to 10. The catalyst is formed of a catalytically active phase, which is connected with the carrier. During this active phase contains a metal in the form of metal joining and/or basic condition, and the carrier is silicon carbide and is at least 40 wt.% the weight of the catalyst. The invention allows obeserving gas with improved selectivity for sulfur. 2 C. and 18 h.p. f-crystals.

The invention relates to a method for direct oxidation at sulfur, catalytic method H2S contained in the gas in low concentrations, and catalyst for the application of this method.

To recover H2S contained in small concentrations, namely at a concentration below 20 vol.% and especially between 0.001 and 20%, benefits the nternet catalytic oxidation of H2S to sulfur by the reaction of H2S + 1/2O2---> S + H2O.

In such ways the processed gas containing H2S in a mixture with the corresponding quantity of gas containing free oxygen, such as air, oxygen or enriched oxygen air, is brought into contact with the oxidation catalyst H2S in sulfur, making contact at temperatures above the dew point of the formed sulfur. In this case, the sulfur in the form of vapour is present in the reaction medium formed from the reaction. Contact can be made at temperatures below the dew point of the formed sulfur. In this case, this sulfur deposited on the catalyst, which requires periodic regeneration of the loaded sulfur catalyst purge using a non-oxidizing gas having a temperature between 200oC and 500oC.

In particular, the oxidation of H2S to sulfur at temperatures above the dew point of sulfur, i.e., at temperatures above approximately 180oC, may be effected by contact with a catalyst consisting of titanium dioxide (European application EP-A-0078690), titanium dioxide containing sulfate of alkaline earth metal (international application WO-A-8302068), OK is ICI-type titanium oxide, zirconium oxide or silicon connected with one or more compounds of transition metals selected among Fe, Cu, Zn, Cd, Cr, Mo, W, Co and Ni, preferably Fe, and, if necessary, with one or more compounds of precious metals, chosen among Pd, Pt, Ir and Rh, preferably Pd (FR-A-2511663), or aluminum oxide, is thermally stable and is connected with one or more compounds of the above-mentioned transition metals, especially Fe, and, if necessary, with one or more compounds of precious metals, chosen among Pd, Pt, Ir and Rh (FR-A-2540092).

Oxidation of H2S to sulfur, held at such temperature that the sulfur is formed on the catalyst, can be carried out in contact with a catalyst consisting, for example of one or more of compounds such as salts, oxides or sulfates of transition metals such as Fe, Cu, Cr, Mo, W, V, Co, Ni, Ag and Mn, in combination with a carrier-type activated alumina, bauxite, silica/alumina or zeolite (FR-A-2277877). In addition, it is possible to carry out this oxidation of H2S with the deposition of sulfur on the catalyst by contact of the catalyst consisting of the catalytic phase, chosen among oxides, salts of linzie N 9302996 from 16.03.1993).

Used for the catalytic oxidation of H2S to sulfur catalysts similar to the above, formed from the catalytic phase based on at least the oxide, salt, or transition metal sulfide connected with the carrier, consisting at least of a material selected among aluminum oxide, titanium oxide, zirconium oxide, silicon dioxide, zeolites, and mixtures of silicon dioxide/aluminum oxide, mixtures of silicon dioxide/titanium dioxide and activated carbon, during prolonged use have some drawbacks. In particular, the catalysts, the bearer of which is formed on the aluminum oxide, is able to make evolution as a result of sulfation. As for the catalysts, the bearer of which consists of activated carbon, in their application to be taken precautions to avoid burning media. In addition, for these various catalysts catalytic phase, impregnating the media has a tendency to migrate into the chain link media, making it difficult or even impossible the recovery of metal from the catalyst phase in a worn-out catalyst. Finally, the above catalysts are mediocre conductivity, ctlaopram coolant.

Now found that it is possible to eliminate the drawbacks of the above-mentioned catalysts of the type used for the catalytic oxidation of H2S to sulfur, and create a way that leads to improved selectivity of sulfur, maintaining its strength over time and forming the carrier of these catalysts on the basis of silicon carbide.

Media with silicon carbide as opposed to media alumina is not a reason for sulfation and unlike media with activated carbon is non-flammable. Additionally, you do not see the migration of the catalytic phase in the circuit carrier with silicon carbide, which makes possible the recovery of metals from catalytic phase, when the catalyst is worn. This possibility is of particular importance in the case of catalytic phase contains harmful substances such as compounds of Nickel. Finally, the media silicon carbide has good thermal conductivity, which allows, in particular when using the catalyst in a chilled catalytic layers, to obtain a smoother front temperature inside the catalytic layer and, hence, the best selectivity of sulfur.

Thus, the subject invention is a method for direct agilents the filing of the above-mentioned gas, containing H2S with a gas containing free oxygen in an amount suitable to maintain the molar ratio of O2: H2S from 0.05 to 10, with the contact of the catalyst for selective oxidation of H2S to sulfur formed catalytically active phase, which is connected with the carrier; called the active phase contains at least the metal present in the form of metal joining and/or in the elemental state, and the media is different in that it consists of silicon carbide.

In particular, the active phase, coupled with the media on the basis of silicon carbide for the formation of the oxidation catalyst according to the invention consists mainly of at least such a transition metal, such as Nickel, cobalt, iron, copper, silver, manganese, molybdenum, chromium, titanium, tungsten and vanadium, the said metal is present in the form of oxide, sulfide, or salt and/or in the elemental state. Called the active phase, in terms of weight of metal, is usually from 0.1 to 20%, in particular from 0.2 to 15% and preferably from 0.2 to 7 wt.% oxidation catalyst. Media silicon carbide is usually at least 40% and especially at least 50 wt.% oxidation catalyst.

Deiseroth from the application of the oxidation method. Mostly called the specific surface area, determined by the method of WET-adsorption of nitrogen at liquid nitrogen temperature (norm NF X 11-621) may be 2 m2/g - 600 m2/g and preferably from 10 m2/g to 300 m2/,

The oxidation catalyst can be prepared by various methods known to include one or more compounds of the metal in a separate solid body constituting the catalyst carrier. In particular, it is possible to act by impregnation of the carrier of silicon carbide, having the form of powder, tablets, granules, extrusion products or other forms agglomerates, solution or colloidal solution in such a solvent as water, one or more desired compounds of the metal, and then drying the impregnated carrier, and calcining the dried product at temperatures that can reach 250oC to 500oC, using inert atmosphere or without it. The calcined catalyst can be subjected to processing recovery under the action of hydrogen, for example between 200oC and 500oC to move in the elementary state of the metal of the metal compounds present in the active phase. You can still provide for the preparation of the catalyst PU is and silicon.

The silicon carbide used for production of catalyst carrier oxidation of H2S to sulfur, may consist of any well-known carbides of silicon, provided that it has the required characteristics of the specific surface, namely, the specific surface area determined by the method of WET-adsorption of nitrogen reaching 2 m2/g to 600 m2/year, mainly from 10 m2/g to 300 m2/,

In particular, the above-mentioned silicon carbide can do, resorting to any of the methods described in the references EP-A-0313480 (corresponding to US-A-4914070), EP-A-0440569, EP-A-0511919, EP-A-0543751 and EP-A-0543752.

The gas containing free oxygen used for oxidation of the sulfur H2S contained in the treated gas is usually air. You can also use pure oxygen, oxygen-enriched air or mixtures of oxygen and inert gas, except for nitrogen in variable proportions. The gas containing free oxygen, and a treated gas containing H2S, can be brought separately in contact with the oxidation catalyst. However, to obtain a very homogeneous gas reaction medium in contact with the catalyst, it is preferable to mix the first processed gas,congestion oxidation.

As mentioned above, the gas containing free oxygen, are used in amounts suitable to obtain a molar ratio of O2: H2S, reaching from 0.05 to 10, especially from 0.1 to 7 and preferably from 0.2 to 4, in the reaction medium coming into contact with the oxidation catalyst H2S to sulfur.

The duration of contact of the gas reaction medium with the oxidation catalyst can be from 0.5 seconds to 20 seconds, preferably 1 second to 12 seconds; these values are given for normal conditions of pressure and temperature.

Method for the catalytic oxidation of H2S to sulfur according to the invention can be applied at temperatures above the dew point of the sulphur formed during the oxidation of H2S; in this case, the aforementioned sulfur is present in the form of steam in the reaction medium, which is in contact with the catalyst and which is collected at the outlet of the catalytic oxidation zone. You can use the oxidation method according to the invention, operating at temperatures below the dew point of the sulphur formed during the oxidation reaction; in this case, the aforementioned sulfur is placed on the catalyst, and the gaseous effluent, collected at the outlet of the oxidation zone is essentially StC and 1000oC. For the application of the method at temperatures above the dew point of the formed sulfur is chosen temperature between 180oC and 1000oC, mainly between 200oC and 900oC. For the application of the method at temperatures below the dew point of the formed sulfur is chosen temperature in the range of 30oC to 180oC and especially in the range from 80oC to 160oC, which includes the area of solidification of sulfur of about 120oC.

Previously in the phase of application of the oxidation reaction, the oxidation catalyst according to the invention and especially the oxidation catalyst active phase which contains Nickel, can be activated by bringing the above catalyst in contact with elemental sulfur in amount, representing a slight excess, for example up to 300 mole%, with respect to the stoichiometric quantity corresponding to the maximum sulphurization of the metal of the active phase of the catalyst; the above-mentioned contacting is carried out in an inert atmosphere, for example in an atmosphere of helium or argon, at temperatures between 250oC and 400oC and for a sufficient time, usually between 1 hour and 4 hours, to obtain the maximum sulphurization of the metal of the active phase toearly as indicated above, allows to obtain the degree of conversion of H2S to sulfur, equal to 100%, since the beginning of the oxidation of H2S into sulfur, oxygen gas containing free oxygen.

The catalyst according to the invention and especially the catalyst with Nickel may be additionally subject to the initial activation, the equivalent activation in elemental sulfur, as described above, by contacting the above-mentioned catalyst with a gas mixture of H2S and inert gas at temperatures between 250oC and 400oC for a sufficient time, usually between 1 hour and 15 hours to achieve maximum sulphurization of the metal of the active phase of the catalyst; the above gas mixture may contain in particular from 0.2 vol.% up to 30 vol.% or above H2S. in particular, containing H2S gas mixture used for the initial activation of the oxidation catalyst, can be obtained from the processed gas, when this latter does not contain, in addition to H2S, components, capable of reacting at temperatures of activation, with the active phase of the catalyst.

The gas containing H2S in small concentrations, which is treated by the method according to the invention, may soderzhanie H2S or gas produced from the gasification of coal or heavy oils, and even gas, resulting from the hydrogenation of sedimentary gas, such as sedimentary gas sulfur plant containing such sulfur compounds as SO2, mercaptans, COS, CS2into H2S under the action of hydrogen or water vapor, or gas, resulting from the processing, in contact with the CLAUS catalyst capable of reaction of formation of sulfur between the H2S and SO2gas effluent containing H2S and SO2in a molar ratio of H2S : O2above 2: 1. The resulting gas contains mainly H2S and does not contain or contains very little SO2as sulfur compounds. The method according to the invention can be used for processing gas containing H2S at a concentration of between about 0.001 vol.% and 25 vol.% and preferably from 0.01 to 20 vol.%. The treated gas may optionally contain such organic sulfur compounds like mercaptans, COS, CS2in total concentration, which can reach approximately 1 vol.%.

Using the method according to the invention, it is possible to process gas containing. H2's in concentrations above 25 vol.%, however, in this SS="ptx2">

The gas containing H2S, which is subjected to oxidation by contact of the catalyst carrier, silicon carbide, can be free from water or essentially free from water or, alternatively, may contain more or less large quantities of water. Thus, the claimed method can be used to treat a gas containing H2S, which has a water content, reaching from 0 vol.% approximately 50 vol.%. Advantageously, when the oxidation reaction gas containing H2S, in contact with a catalyst according to the invention, especially with the Nickel catalyst with a native silicon carbide, apply at temperatures below the dew point of the sulphur formed by oxidation, and particularly at temperatures below the melting point of sulfur; the presence in the processed gas containing H2S, the amount of water reaching from 10 vol.% up to 50 volume. % and preferably from 15 volume. % to 30 vol.%, can significantly increase the time during which the efficiency of the catalyst is maintained at optimum level.

When carrying out the method according to the invention at temperatures between 180oC and 1000oC and especially between 200oC and 900oC, contacting the treated gas with the oxidation catalyst with the nose is awnym way when the content of H2S in the processed gas is not higher than about 5 vol.%, or in most oxidized zones arranged in a row, each containing the oxidation catalyst, mainly when the contents of the H2S in the processed gas is higher than about 5 vol.%; in the above-mentioned one oxidation zone or in each of the most oxidized zones operate at temperatures in the above ranges. In each of the zones of oxidation operate in the temperature region corresponding to the quite optimum selectivity of the catalyst for the formation of sulphur.

The output from one oxidation zone or from each of the most oxidized zones arranged in a row, select the effluent gas, steamy sulfur; named effluent gas before any subsequent processing to remove the H2S, is sent to the separation zone of sulphur, which by condensation released from the greater part of the sulphur which it contains. When the gas containing H2's handle passing through the most located in a number of zones of oxidation, containing the oxidation catalyst with a native silicon carbide, is the oxidation of sulfur in each of the above areas only fractions of H2S contained the zoom, filed in this zone, the corresponding quantity of gas containing free oxygen, the oxidation of the sulfur. The number of H2S subjected to oxidation to sulfur in each of the zones, which is part of the total number of H2S contained in the treated gas is mostly between 2 vol.%, and 5 vol.% the treated gas, and the number of zones catalytic oxidation is chosen so that the treated gas from the last catalytic zone, contained a maximum of 5 vol.% H2S.

If necessary, the gaseous effluent, which is collected at the outlet from one oxidation zone or at the outlet of the last zone of the majority are located in a number of zones of oxidation when applied at temperatures above the dew point of the formed sulfur, can be subjected to additional processing to clean after separation of the sulphur, which he in certain cases contains; the above processing depends on the nature of the gaseous sulfur compounds remaining in affluence.

The application of the method according to the invention at temperatures above the dew point of the formed sulfur may be present, in particular, the stage of oxidation of H2S for ways to remove sulfur seeable acid gas, described in FR-A-2589140. The above application can also show the stage of oxidation of H2S to sulfur in CLAUS stoichiometry on, used in the methods of the type described in FR-A-2511663 or in FR-A-2540092; these methods include contacting the gas having a content of H2S below 25 volume. %, at elevated temperature, i.e. between 200oC and 1000oC and especially between 350oC and 900oC and in the presence of the oxidation catalyst H2S with a controlled quantity of gas containing free oxygen, to obtain a gas effluent containing H2S and SO2in a molar ratio of H2S : SO2equal to 2 : 1, and a quantity of sulphur; then in bringing the above-mentioned gas effluent after cooling and, if necessary, separating the contained sulfur in contact with the CLAUS catalyst to form a new quantity of sulphur; the above catalyst CLAUS is located in one catalytic Converter or catalytic converters, for example two or three, arranged in a row.

When using the method according to the invention at temperatures below the dew point of the sulphur formed during the oxidation of H2S, i.e., at temperatures in the " gas which in this form of administration contains preferably less than 5 vol.% H2S and especially less than 2 vol.% H2S, with the oxidation catalyst with a native silicon carbide leads to the formation of sulfur that is deposited on the catalyst.

If the concentration of H2S and/or the temperature of the processed gas containing H2S provided in contact with the oxidation catalyst, such that, due to strong ekzotermicheskie reaction H2S + 1/2O2---> S + H2O, the temperature of the reaction medium exiting the stage of oxidation, may exceed the temperature limit above which the reaction is not more than the desired selectivity, remove calories, released as a result of the above reaction, subjecting the catalyst cooled by any known method. It is possible, for example to perform this cooling using a cold fluid circulating in indirect heat exchange with the above catalyst within this latter. You can also work by placing the catalyst in a tubular reactor, formed located in the calender tubes, for example with a catalyst present in the pipes, and cold fluid circulating between the tubes from the side of the calender. You can also osprey between successive layers indirect heat exchange with a cold fluid, or heat transfer occurring inside or outside the reactor oxidation.

If the processing gas contains in addition to the H2's a significant amount of water, for example above 10 volume. % temperature oxidation of H2S to sulfur below the dew point of the sulphur formed during the oxidation, choose mostly above the dew point of the water contained in the treated gas.

During the oxidation of H2S to sulfur at temperatures below the dew point of the formed sulfur oxidation catalyst is gradually saturated with sulphur. Periodically produce regeneration of the catalyst is saturated with sulfur, blowing using a non-oxidizing gas at temperatures between 200oC and 500oC and preferably between 230oC and 450oC for evaporation of sulphur, was arrested on the catalyst, then cooled regenerated catalyst to a temperature below the dew point of sulfur for the new application of the oxidation reaction, this cooling is carried out using a gas having an appropriate temperature below 180oC.

The flushing gas used for the regeneration of the saturated sulfur catalyst may be methane, nitrogen, CO2or a mixture of these gases, or may consist of a fraction of the gas stream which has been created for regeneration, may if necessary contain some amount of gaseous reducing compounds, such as H2, CO, or H2S, at least in the last phase of regeneration, i.e., after evaporation of most of the sulphur deposited on the catalyst oxidation.

The use of the oxidation reaction according to the method according to the invention at temperatures below the dew point of the formed sulfur can be carried out in a single oxidation zone containing an oxidation catalyst with a carrier of silicon carbide, which operates alternately in phase oxidation and in the recovery phase/cooling. This application occurs when the treated gas contains little H2S and therefore the regeneration of the catalyst a bit not too rapid. It is advantageous to carry out the catalytic reaction in most oxidized zones, each containing the oxidation catalyst with a carrier of silicon carbide, which operate in such a way that at least one of the above areas of work in phase regeneration/cooling, while other zones are in-phase catalytic oxidation. You can also conduct a process having one or more zones in the phase oxidation reaction, at least one zone in the phase of risutora oxidation, circulates mainly in a closed circuit, starting with zone heating, passing successively through the catalytic zone during regeneration, and through the cooling zone in which the greater part of the sulphur in the above-mentioned gas is separated by condensation to return to the zone of heating. Of course, the regeneration gas may also circulate in the circuit open.

The gas used for cooling the regenerated catalyst oxidation, is a gas of the type used for the regeneration of the saturated sulfur catalyst. The above gas, if necessary, may contain oxygen in a quantity less than or equal to the number used in the phase catalytic oxidation. Chain gas and regeneration gas cooling can be independent from each other. However, one variant of implementation, the circuit gas recovery, defined above, may also include the branch connecting the output of the cooling zone input zone during regeneration, with bypass zone heating, which allows to avoid the above-mentioned zone heating and use the regeneration gas as gas cooling.

Possible application of the method according to the invention for the oxidation of H22S, which follows the stage of the CLAUS reaction at temperatures below 180oC method of desulfurization of gas containing H2S described in FR-A-2277877.

The invention is illustrated by the following examples without limiting method according to the invention.

Example 1.

Processed gas consisting of 1 vol.% H2S, 5 vol.% H2O and 94 vol.% CO2at temperatures above the dew point of the formed sulfur, using a catalyst consisting of a carrier of silicon carbide impregnated compound of iron and chromium compound and containing a given weight of metal relative to the weight of the catalyst, 3.2% of iron and 0.35% of chromium.

The preparation of the catalyst was carried out as follows. First I soaked the grains of silicon carbide having a grain size distribution between 0.8 mm and 1 mm and a specific surface area of WET 78 m2/g, a solution of compounds of iron and chromium compounds in concentrations suitable to obtain the desired quantities of iron and chromium in the resulting catalyst. The obtained impregnated product was dried at room temperature for 40 hours, then at 120oC for 50 hours and then subjected to calcination at 500oC for 20 hours to Rome and had a specific surface area BET 77 m2/,

Processing gas containing H2S, was carried out in a catalytic reactor with a porous layer containing 1.1 m3catalyst; the above reactor was equipped with, first, the intake manifold for the processing of gas and, secondly, the pipeline for removal of formed gases at the outlet of the reactor. Intake pipe for gases has a hole for injection of air as a gas containing free oxygen, and is provided with, in addition, an indirect heat exchanger, working with the heater mounted between the hole for injection of air and the inlet of the reactor. Outlet piping for gas supplied by a sulfur condenser, cooled by circulation of water vapor. The passage of inlet gas at the reactor exit is produced through the catalyst bed.

In the processing gas introduced through the inlet pipe for gas at a flow rate of 1000 nm3per hour and at a temperature of 40oC add through the air hole, respectively, at a flow rate of 29 nm3per hour, the air is injected at room temperature. The processed mixture of gas and air, in which the molar ratio of O2: H2S was equal to 0.6, introduced at a temperature of 180oC is Noah mixture with the catalyst, contained in the reactor was 4 seconds. The gaseous effluent leaving the reactor through a pipeline to remove gases contained no free oxygen or H2S and had a temperature of 240oC. This effluent was cooled to approximately 130oC in the condenser for separating sulphur which it contains.

The transformation of H2S was full and selectivity of sulfur was equal to 92%.

Example 2.

Processed sedimentary gas effluent containing 0.8 vol.% H2S as one sulfur compound was obtained by hydrogenation/hydrolysis sedimentary gas plant sulfur according to the method CLAUS, which was treated with acid gas containing 70 vol.% H2S.

The processing of the above-mentioned gas effluent carried out at a temperature below the dew point of sulfur, formed by oxidation of the above-mentioned H2S using a catalyst consisting of silicon carbide, impregnated with a compound of Nickel and containing 4 wt.% Nickel; the above catalyst has a specific surface area BET of 220 m2/,

The above catalyst was obtained by impregnation of microporous grains of silicon carbide appropriate amount of Nickel acetate is that if 300oC for 3 hours. Grains of silicon carbide with an average diameter of 1 mm had a specific surface area BET of 240 m2/,

Worked on the installation formed of two reactors for catalytic oxidation, mounted in parallel. Each reactor has an inlet and outlet separated by a porous layer of the above-mentioned catalyst. Above the reactors were also installed so as to alternately using switchable clockwork valves, one of the reactors worked during the reaction phase, i.e., had an input connected to the intake manifold for gas, on which is mounted an indirect heat exchanger and below the heat exchanger has a hole for injection of air, and the output associated with the pipeline to remove gases and other reactor worked in phase regeneration/cooling, i.e., was located in the circuit of regeneration/cooling provided with means to circulate gas blowing through the oxidation reactor from the heater to the sulfur condenser and return to the specified heater and circulation then cold gas having the same composition as the regeneration gas through the reactor after regeneration.

The treated effluent gas flowing through Antonovna on the above pipeline, then added through the hole 44 KMOL/hour ambient air. The resulting mixture enters the reactor in the phase oxidation with temperature equal to the 90oC. the contact Time of the gas mixture entering the reactor during the reaction phase oxidation with a catalyst bed contained in the above reactor was equal to 10 seconds. The degree of transformation of H2S in the reactor during the reaction phase oxidation was equal to 100%. The output from the specified reactor remove gas stream having a temperature of approximately 140oC and containing 160 v.p.'m SO2, the above-mentioned gas stream is directed into the furnace for burning waste before it is released into the atmosphere.

In a reactor operating in the regeneration phase/cooling, injected purge gas for regeneration of the oxidation catalyst saturated with grey; the aforementioned purge gas comprised of nitrogen and injected into the specified reactor temperature between 250oC and 350oC and with a flow rate of 10000 nm3/hour. At the end of the regeneration phase of the catalyst reduces the temperature of the purge gas to approximately 125oC and kept blowing the purge gas is cooled to a until a layer of regenerated catalyst does not reach the above temperature. Prinia worked alternately for 30 hours during the reaction phase and within 30 hours, of which 10 hours were cooling, phase regeneration/cooling.

Plant for the production of sulfur, comprising the method according to the invention for processing the resulting sedimentary gases, hydrogenated pre-processing according to the invention, had an overall sulfur recovery of 99.9 % in a few months.

Example 3.

Treated acid gas, poor H2S. the Specified gas consisted of 95,5 volume.% CO2, volume 4. % H2O and 0.5 vol.% H2S.

The processing of sour gas is carried out at a temperature below the dew point of the sulphur formed by the oxidation of H2S the sour gas, working on the installation, such used in example 2, and using a catalyst consisting of silicon carbide containing 4 wt.% Nickel and having a specific surface area BET of 210 m2/, This catalyst was prepared as described in example 2, and after calcinations he underwent restoration in the stream of hydrogen at 400oC for 10 hours.

The treated acid gas, poor H2S, was admitted through the inlet pipe for gas at a flow rate 2241 nm3per hour and at a temperature of about 30oC brought to a temperature of 80oC in the heat exchanger, Montero is about 80oC. the resulting mixture into the reactor in phase oxidation at a temperature of 80oC. the contact Time of the gas mixture entering the reactor during the reaction phase oxidation with a catalyst bed contained in the above-mentioned reactor was equal to 10 seconds. The degree of transformation of H2S in the reactor during the reaction phase oxidation was equal to 100%. The output of the above reactor was removed gas stream having a temperature of approximately 105oC and containing less than 100 v.p.'m SO2gas flow was directed into the furnace for burning waste before it is released into the atmosphere.

In a reactor operating in the regeneration phase/cooling, injected purge consisting of nitrogen gas, in order to regenerate the oxidation catalyst saturated with sulfur, then cooled regenerated catalyst, working as described in example 2. When regeneration of a nitrogen atmosphere Recuperat all sulfur deposited on the catalyst.

The oxidation reactors worked alternately for 30 hours during the reaction phase and within 30 hours, of which 10 hours were cooling, phase regeneration/cooling.

Example 4.

Handle sour gas containing 20 vol.% H2S, 8 vol.% water and 72 volume. % CO2on Spasojevi in two successive stages: first, above the dew point of the formed sulfur and the other below the above the dew point.

Worked on the installation, including the following elements:

the oxidation reactor with a fixed bed containing an oxidation catalyst according to the invention, provided with an inlet pipe for the mixture of acid gas and air and pipeline removal effluent oxidation;

- heat exchanger for indirect heat exchange gas/gas, one of the circuits of the heat exchange which is mounted in series in the intake manifold of the mixture of acid gas and air, and the other circuit of the heat exchange is in line with the pipeline to remove effluent oxidation;

- primary catalytic Converter with a fixed layer, which contains a CLAUS catalyst in the form of extrudates with a diameter of 3 mm, consisting of titanium dioxide, containing 10 wt.% calcium sulphate; the input to the Converter is connected with tubing to remove effluent oxidation through the corresponding circuit of the heat exchanger;

battery - catalytic conversion, including two secondary catalytic Converter and one sulfur condenser, cooled with water vapor. In the battery, first, each of the above-mentioned secondary Converter contains a catalyst for the e converters and sulfur condenser are thus the output of the primary Converter can be switched alternately to the input of one or the other of the above secondary converters, so that these latter are connected in series through a capacitor sulfur; and

- bake for catalytic combustion of waste, the entrance to which is connected to the output from the battery, catalytic conversion, and the output is connected to open into the atmosphere by an exhaust pipe, the furnace for combustion contains a catalyst consisting of silica impregnated with sulphate of iron, and palladium oxide.

The oxidation catalyst used in stage oxidation stoichiometry on KLAUS, consisted of media silicon carbide, impregnated with a compound containing iron and 4.6 wt.% iron relative to the total weight of the catalyst.

The preparation of the catalyst was carried out as follows. First I soaked the grains of silicon carbide having a grain size distribution between 0.8 mm and 1 mm and a BET specific surface 78 m2/g, using an aqueous solution of ferrous sulfate at a concentration suitable for the desired amount of iron in the resulting catalyst. The obtained impregnated product was dried and progulivali as described in example 1.

The resulting catalyst contained, as is the at the rate of 1000 nm3/h (standard conditions) was added 285,6 nm3/h of air and the resulting gas mixture is pre-heated to a temperature of 200oC passing through the heat exchanger, and then injected into the oxidation reactor. The contact time between the gas mixture and the oxidation catalyst was equal to 2 seconds (standard conditions), and the temperature inside the catalyst bed was increased to 800oC.

Effluent from the oxidation reactor contains H2S and SO2in a molar ratio of H2S : SO2equal to 2:1, and 6 v.p.m. free oxygen and the amount of vaporous sulfur which corresponds to the transformation of H2S to sulfur 59%.

This effluent was cooled to 150oC in a heat exchanger to condense the sulphur which it contains, and to use some calories above effluent for pre-heating a mixture of acid gas and air. Then the cooled effluent was re-heated to 250oC and sent to the primary catalytic Converter CLAUS. The contact time between the catalyst based on titanium dioxide and a gas effluent in the above-mentioned Converter was approximately 3 seconds and the temperature inside the catalytic layer was 300ooC with a contact time of gas/catalyst for approximately 6 seconds. Gas, saturated with sulfur, resulting from the Converter during regeneration, is then in the sulfur condenser, cooled with water vapor, which is called the gas was cooled to a temperature of approximately 150oC and freed from sulphur which it contains, by condensation. The resulting cooled gas containing H2S and SO2and a very small amount of vaporous sulfur was passed to the catalytic Converter in the phase "reaction CLAUS" batteries and catalytic conversion, operating at a temperature of 150oC, the contact time of the gas/catalyst approximately 6 seconds to produce sulphur by reaction between H2S and SO2. The formed sulfur deposited on the catalyst.

Sedimentary gases flowing from the Converter in the phase "the CLAUS reaction", filed in the furnace for catalytic combustion of waste, and flue gases resulting from the furnace for combustion, which contained SO2in PTS who>Sedimentary gases leaving the battery catalytic conversion, did not contain more than 800 v.p.m. all sulfur, namely H2S, SO2, vaporous and/or bubble sulfur, equivalent to the total output of conversion of H2S to sulfur, equal to 99.6%.

After time over 800 hours in the above-mentioned conditions, the effluent of the reactor for the catalytic oxidation in CLAUS stoichiometry contained H2S and SO2in a molar ratio of H2S : SO2equal 2,02 and when the amount of gaseous sulfur corresponding to the degree of conversion of H2S 56%, the total yield of the conversion of H2S to sulfur was 99.4%.

Example 5.

Processed gas consisting of 1 vol.% H2S, 5 vol.% H2O and 94 vol.% CO2at temperatures above the dew point of the formed sulfur, using a catalyst consisting of a carrier of silicon carbide impregnated compound of iron and chromium compound and containing a given weight of metal relative to the weight of the catalyst, 3.2% of iron and 0.35% of chromium. The catalyst was activated by direct sulfonation.

The preparation of the catalyst was carried out as follows.

First I soaked the grains of silicon carbide having a grain size distribution between 0.8 tion, suitable for obtaining the desired quantities of iron and chromium in the resulting catalyst. The obtained impregnated product was dried at room temperature for 40 hours, then at 120oC for 50 hours and then subjected to calcination at 500oC for 20 hours. The obtained calcined product containing the elements iron and chromium in the form of oxides, deposited on silicon carbide, treated then or with the help of H2S, diluted at a concentration of 1 vol.% in a stream of helium or solid grey, mechanically mixed with the catalyst, the amount of sulfur amounted to 6.2 wt.% the weight of the catalyst. The above processing was carried out at 300oC for two hours, to convert the iron and chromium in the form of sulfur compounds forming the active phase of the catalyst.

The obtained sulfur catalyst contained, as indicated above, 3.2 wt.% iron and 0.35 wt.% chromium and had a BET specific surface 76 m2/,

Processing gas containing H2S, was performed using sulfur catalyst, working as described in example 1.

The transformation of H2's been full since the beginning of the treatment containing H2's gas and sulfur selectivity was 93%.

About 0.5 vol.% H2S.

The processing of sour gas was carried out at a temperature of 100oFrom below the dew point of sulfur, obtained by the oxidation of H2S the sour gas, working on the installation, which is similar to used in example 2, and using a catalyst consisting of silicon carbide containing 4 wt.% Nickel and having a specific surface area BET of 210 m2/, This catalyst prepared as described in example 2, and after annealing was subjected to restoration in the stream of hydrogen at 400oC for 10 hours.

Processed, poor H2S sour gas received through the inlet pipe for gas at a flow rate 2241 nm3per hour and at a temperature of about 30oC; it was brought to a temperature of 80oC in the heat exchanger, mounted above the pipe, then mixed through the hole with 89,6 nm3/h of air and 1000 nm3/h of inert gas saturated with 55 vol.% water vapor, and brought up to 100oC. the Amount of water vapor contained in the final mixture, was equal to about 20 vol.%. The resulting mixture was supplied to the reactor in phase oxidation with a temperature of 86oC. the contact Time of the gas mixture entering the reactor in the phase of realeastate in phase oxidation reaction was 100%. The output of the above reactor was removed gas stream having a temperature of approximately 110oC and containing at least 100 v.p.'m SO2. This gas stream was directed into the furnace for burning waste before it is released into the atmosphere.

In a reactor operating in the regeneration phase/cooling, injected purge gas consisting of nitrogen, for regeneration of the oxidation catalyst saturated with sulfur, then cooled regenerated catalyst, working as described in example 2. When regeneration of a nitrogen atmosphere Recuperat all sulfur deposited on the catalyst.

The presence of the above-mentioned amount of water vapor in the reaction mixture is usually in amounts of between 10 vol.% and 50 volume. %, especially between 15 volume. % and 30 vol.%, can significantly lengthen the time maintaining the optimum activity of the desulfurization catalyst. Water vapor plays a role dispersant sulfur deposited on the catalyst, and, therefore, prevents the access of reactants to the active centers of the catalyst.

1. The method of oxidation in the environment of the catalytic method H2S is contained in a small concentration in the gas on which the specified gas containing H2S, process gas, the content is of a catalytically active phase, connected with the carrier, with the active phase contains at least a metal, characterized in that the gas contains free oxygen in an amount providing a molar relationships O2:H2S from 0.05 to 10 contained in the active phase metal is present in the form of metal joining and/or in the elemental state, and the carrier is silicon carbide and is at least 40 wt.% the weight of the catalyst.

2. The method according to p. 1, characterized in that the active phase, coupled with a native silicon carbide for the formation of the oxidation catalyst comprises a transition metal, in particular of such metal as Nickel, cobalt, iron, copper, silver, manganese, molybdenum, chromium, titanium, tungsten and vanadium, with the specified metal is present in the form of an oxide, salt or sulfide and/or in the elemental state.

3. The method according to p. 1 or 2, characterized in that the medium is silicon carbide is at least 50 wt.% by weight of the oxidation catalyst.

4. The method according to one of paragraphs.1 to 3, characterized in that the active phase of the oxidation catalyst, calculated on the weight of the metal is from 0.1 to 20 wt.%, in particular from 0.2 to 15 wt.% and preferably from 0.2 to 7 wt.% the weight is and, determined by the BET method of nitrogen adsorption, has a value of from 2 to 600 m2/,

6. The method according to one of paragraphs.1 to 5, characterized in that the gas containing free oxygen, are used in amounts suitable to obtain a molar ratio of O2:H2S from 0.1 to 7, and particularly from 0.2 to 4.

7. The method according to one of paragraphs.1 - 6, characterized in that the contact time of the gaseous reaction medium with a catalyst for oxidation under normal conditions of pressure and temperature is from 0.5 s to 20 s, and predominantly from 1 to 12 C.

8. The method according to one of paragraphs.1 to 7, characterized in that the oxidation of H2S in contact with the catalyst is carried out at temperatures between 30 and 1000oC.

9. The method according to p. 8, characterized in that the oxidation of H2S in contact with the catalyst is carried out at temperatures between 180 and 1000oC and preferably between 200 and 900oC.

10. The method according to p. 8, characterized in that the oxidation of H2S in contact with the catalyst is carried out at temperatures below the dew point of sulfur formed as a result of oxidation, lying in the range from 30 to 180oC and especially in the range from 80 to 160oC, while the formed sulfur deposited on the catalyst.

oC and preferably between 230 and 450oC, detained on the catalyst sulfur is evaporated, then cooled regenerated catalyst to a temperature below the dew point of sulfur for the new application in order oxidation of H2S, with cooling carried out using a gas having a temperature below 180oC.

12. The method according to one of paragraphs.1 - 11, characterized in that the content of H2S in the processed gas is between 0.001 and 25 vol.% and especially from 0.01 to 20 vol.%.

13. The method according to one of paragraphs.1 - 12, characterized in that the pre-oxidation catalyst with a native silicon carbide activated by contact with sulfur, the amount representing the excess to 300 mol.% the number corresponding to the maximum sulphurization of the metal of the active phase of the oxidation catalyst, the contacting is carried out in an inert atmosphere at a temperature between 250 and 400oC.

14. The method according to one of paragraphs.1 - 12, characterized in that before the application of the oxidation catalyst with a native silicon carbide activated by contacting with a gas mixture of H2S and inert gas at temperatures between 250 and 400oC for a time between 1 and 15 h to achieve a four-s is but from 0.2 to 3% vol. H2S.

15. The method according to one of the FG1 - 9, characterized in that use oxidation reaction H2S in stoichiometry by Klaus contacting the treated gas containing H2S, in the presence of an oxidation catalyst with a carrier of silicon carbide and at temperatures between 200 and 1000oC, in particular between 350 and 900oC, with a controlled quantity of gas containing free oxygen, to obtain a gas effluent containing H2S and SO2in a molar ratio of H2S : SO22 : 1, and some sulphur, and named effluent gas after cooling and, if necessary, separation of the contained sulfur is brought into contact with a Claus catalyst to form a new quantity of sulphur.

16. The catalyst for the direct selective oxidation of H2S to sulfur-containing catalytically active phase, is connected with a carrier consisting of silicon carbide, while the active phase contains at least a metal, wherein the metal is present in the form of metal joining and/or elemental state and the media is at least 40 wt.% the weight of the catalyst.

17. The catalyst according to p. 16, characterized in that the active phase, l, cobalt, iron, copper, silver, manganese, molybdenum, chromium, titanium, tungsten and vanadium, the said metal is present in the form of a salt or oxide sulfide and/or in the elemental state.

18. The catalyst according to p. 16 or 17, characterized in that the active phase of the oxidation catalyst, calculated on the weight of the metal is from 0.1 to 20 wt.%, in particular from 0.2 to 15 wt.% and preferably from 0.2 to 7 wt.% the weight of the catalyst.

19. The catalyst according to one of paragraphs.16 to 18, characterized in that it has a specific surface area determined by BET method of nitrogen adsorption, from 2 m to 600 m2/g and preferably from 10 to 300 m2/,

20. The catalyst according to one of paragraphs.16 to 18, characterized in that the medium comprises at least 50 wt.% the weight of the catalyst.

 

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