Catalyst for the selective oxidation of sulphur compounds and process for the selective oxidation of sulfur compounds to elemental sulfur

 

(57) Abstract:

The invention concerns a catalyst and method of selective oxidation of sulfur compounds to elemental sulfur, comprising at least one catalytically active component selected from the group of oxides: iron, chromium, manganese, cobalt and/or Nickel, and the carrier is silica, the catalyst has a specific surface area of more than 20 m2/g and the average radius of the pores is at least 25 , and this catalyst does not show significant activity in relation to the Claus reaction. 2 S. and 2 C.p. f-crystals, 13 tables.

This invention relates to the field of heterogeneous catalyst and relates to a catalyst and method of selective oxidation of sulfur compounds to elemental sulfur.

In U.S. patent N 4.818.740 disclosed a catalyst for selective oxidation of hydrogen sulfide to elemental sulfur, which prevents adverse effects to a large extent, while the main reaction

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passes with a sufficient degree of conversion and selectivity.

The catalyst according to this patent includes a carrier, the surface of which is available for the gas phase, not proyavlyeniya specific surface area of the catalyst is less than 20 m2/g and less than 10% of the total pore volume of the pores of the catalyst has a radius in the range of 5 to 500 .

Also known catalyst for oxidation of serosoderjaschei compounds, particularly hydrogen sulfide containing oxides of chromium and iron on silicon dioxide as a carrier (see application for French patent N 2481254).

Although these catalysts represent significant progress in the field of removal of sulfur compounds from gas mixtures, it was found that desirable and possible further improvements.

Due to the limitations regarding the amount of specific surface area and distribution of the pores, which plays an important role in achieving the desired results, limiting thus spread on the amount of active material that can be deposited on the carrier. As a result, the output of sulfur, which can be obtained with the catalyst at a specified U.S. patent, is somewhat limited. Due to what is described in this patent, the catalyst has a relatively high temperature of initiation, we have to work with low speed and use a number of the catalyst, or the end-gas temperature and the catalyst layer will be so high that the selective oxidation of sulfur compounds to elemental sulfur, which has a higher value of specific surface area, but which does not have the disadvantages arising from the catalyst with a large specific surface, described in the mentioned U.S. patent.

The invention concerns a catalyst for the selective oxidation of serosoderjaschei compounds, particularly hydrogen sulfide to elemental sulfur-containing catalytically active substance selected from the group of oxides: iron, chromium, manganese, cobalt and/or Nickel, on the media of silicon dioxide; the catalyst differs in that it has a specific surface according to BET of 20.1 350 m2/g, the average radius of the pores is equal to 32 1980 angstroms and contains from 1 to 10 wt. the specified active substance, the rest of the media.

The catalyst according to the invention may additionally contain as a promoter from 0.05 to 1 wt. phosphorus compounds and/or sodium.

It has been unexpectedly discovered that such a very specific catalyst at a relatively large value of the surface has good activity along with good selectivity. Indeed, given the fact that disclosed in the mentioned U.S. patent, the expected improvement activity, but also that the selectivity of elemental sulfur will be significantly lower. Oka is the radius of the pores and minimal activity in the Claus reaction.

This last requirement is very strict, and when the specific surface area exceeds 20 m2/g, satisfies this requirement limited number of substances. In General, substances used in examples in the mentioned U.S. patent N 4.818.740 do not satisfy this requirement if their specific surface area exceeds 20 m2/, Used mainly aluminum oxide, which always contains a certain amount of oxide of aluminum, which is very active against the Claus reaction in the case of this specific surface.

Therefore, the present invention allows a serious problem, making it possible to use a catalyst which has the advantages of the catalyst according to U.S. patent N 4.818.740, and at the same time can have a significant specific surface area. Particularly surprising is that when using the features of the invention, namely, with minimal or zero Klaus-activity", in combination with the average radius of the pores at least get a catalyst having good activity along with good selectivity.

One of the advantages of the catalyst according to the invention is that it results in a significant improvement in activity per unit volume of catalyst">

The present invention is based on a thorough investigation of the mechanism of oxidation of hydrogen sulfide. It is established that elemental sulfur is not significantly oxidized to sulfur dioxide in the presence of hydrogen sulfide. It is known that elemental sulfur is present mainly in the form of eight-membered or six-membered rings at temperatures of from 180 to 300oC, however, the oxidation of the sulfide sulfur atoms present in the catalyst and the catalyst surface in the form of components containing less sulfur atoms.

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As mentioned, the sulfur atoms in the oxidation of hydrogen sulfide, react, forming a ring-shaped molecules. Ring-shaped molecules are in equilibrium with biradicals chains of sulfur atoms. Six - and eight-membered rings are fairly stable, so the equilibrium is shifted almost completely to the left. Small rings are less stable, so the equilibrium shifts to the right. Radicals are very reactive, and they are in the absence of hydrogen sulfide will quickly react with oxygen (which is always present in excess) to form sulfur dioxide. Therefore, you can expect considerable extent, forming sulfur dioxide.

However, when hydrogen sulfide is present, it reacts with radicals to form polysulfides according to the following reactions:

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When the hydrogen sulfide reacts with radicals present at the ends of the chains of sulfur atoms, the oxidation leads to the destruction of mostly hydrogen atoms from the ends, and therefore, oxidation to sulfur dioxide will not occur.

We conducted an experiment in which hydrogen sulfide is oxidized in the catalyst bed contained within a vertical tubular reactor with a diameter of 2 cm Inside the small catalyst layer temperature was uniform. It was found that the selectivity remains above 90% until then, until you reach 100% conversion and until there is hydrogen sulfide. Without the presence of hydrogen sulfide are oxidized to sulfur dioxide, as a result, the selectivity decreases.

Therefore, to achieve high selectivity, it is important to maintain a significant concentration of hydrogen sulfide in the entire catalyst bed.

In the layer of catalyst used in this experiment was observed pulse period. In horizontal cross-section of the layer of catalystsa gaseous components, present in the gas stream, was also the same. Because of the porous catalyst particles were small, the length of the pores inside the mass of catalyst was limited. Therefore, the concentration of hydrogen sulfide has not changed significantly within the catalyst particles. The fact that the decrease in selectivity is not simply a consequence of the high temperature required to achieve full conversion, confirmed by the results of experiments conducted with native speakers of silicon dioxide having different specific surface area. The recovery of sulphur, which is the target product of conversion and selectivity were measured for catalyst having a specific surface area of 20 m2/, Small active specific surface area indicates that to achieve full conversion of hydrogen sulfide requires a relatively high temperature. The catalysts used in the other experiments, had a specific surface area of more than 45 m2/, Found that the higher the active specific surface area leads to higher activity, which indicates that the hydrogen sulfide is completely reacts at a lower temperature and that the recovery of sulfur begins sniatia essentially uniform concentration within the particles. However, in industrial reactors with a fixed layer of small particles of the catalyst cannot be used, because it would be a too high pressure drop in the catalyst bed of small particles.

In large pores present within the larger catalyst particles, it is much harder to maintain essentially uniform concentration of hydrogen sulfide. When the concentration of hydrogen sulfide in the centre of mass of the catalyst particles decreases to very low levels, oxidation occurs before formation of the sulfur dioxide, excess oxygen, which is used in accordance with the present invention.

In the application of industrial reactors prerequisite for achieving high selectivity elemental sulfur in the oxidation of hydrogen sulfide is the use of catalyst particles having a wide pores, to ensure a sufficiently rapid transfer of hydrogen sulfide inside the pores of the catalyst. When using large particles of catalyst concentration is significantly reduced from the outer edge to the center of the mass of the catalyst, on the other hand, the concentration is essentially uniform in the application of small particles.

Thus the invention is based is stationary catalyst in industrial reactors. The catalyst can be obtained from the particle carrier having the desired shape and dimensions, as well as a wide pores, as required in accordance with this invention. There are a wide variety of media from silicon dioxide, making it easy to choose the media required to achieve high selectivity.

The active ingredient must be evenly distributed on the surface of the carrier in the form of a thin layer or isolated small particles.

However, the active component should not precipitate inside the particles of the medium in the form of clusters of small particles, closing the narrow pores, as in this case, the hydrogen sulfide will not be able to enter the porous active material fast enough. The media should also not react with the catalytically active precursor with the formation of a rigid body with a high porosity and a narrow pore.

When the precursor compound of the active metal is applied on the pre-molded carrier particles in accordance with the method commonly used in the industrial production of catalysts, that is, by impregnation with a solution of nitrate, drying and calcination, observed the formation of small clusters of castio metal is absorbed by the porous particle system media. During the drying process, small particles of the active component first crystallize on the outer edges of the surface of the particles of the carrier and inside the holes then. The result of capillary forces transferred the remaining liquid in narrow pores, and the pores inside the particles of the carrier are emptied. Finally, the active precursor is deposited mostly completely on the outer surface of the carrier particles in the form of small clusters, covering a narrow pores.

For the preparation of the catalyst in accordance with the invention were applied, for example, the method of "dry" impregnation or impregnation with a "capacity" using solutions of the corresponding complex iron compounds, the pH value of which must be adjusted to the desired level. Thus, in accordance with the present invention the required distribution of small particles of iron oxide on the surface of the carrier is achieved by impregnation bad kristalltherme complex compounds of iron, which greatly moisten silicon dioxide, for example, complexes with ethylenediaminetetraacetic acid with a pH value above about 7 or citric acid. The micrograph showed that the impregnated and dried media ablauts on the surface of the carrier, and with a uniform distribution of the active substance.

The problems associated with the conventional method of impregnation and drying, gave the author the present invention to develop a deposition method in which the precursor of the active substance is uniformly precipitated on the surface of the carrier being suspended in the solution of the precursor of the active substance. Typically, the deposition method is used, the powder carrier, and after deposition of the precursor of the active substance rich media filtered, washed and dried and, finally, the process for making the particles forms required for use in reactors with a fixed layer. It is clear that control over the distribution of the final pore size required is much less than in the known method.

However, when the deposition of the precursor of the catalytically active substances are usually reacts with the carrier, forming a highly porous solid having narrow pores. The precursor of the active substance precipitated from homogeneous solution, reacts with the carrier. Typically, this reaction is preferred because getting the catalyst with high specific surface area and the following is ay restore to metal. Especially silicon dioxide is very prone to intense reactions with ions of divalent metal as precursors during deposition.

The diatomaceous earth with a specific surface area of 10 to 15 m2/g reacts during the deposition of copper (II) obtaining a solid substance having a specific surface area of 100 to 150 m2/, Thus it is clear that this method cannot be applied to obtain catalysts with enough controlled distribution of pore size, which contain a wide pores in accordance with the present invention.

The reaction medium can be easily assessed by an increase sensible surface (measured, for example, by the BET method) after deposition of the precursor of the active substance.

It should be noted that in this application the lack of "Klaus-activity" is defined as the lack of influence of water on the selectivity of the oxidation reaction of hydrogen sulfide to sulfur in the presence of the minimum stoichiometric amount of O2if 250oC. More specifically, this means that in the presence of about 30. water selectivity of the reaction towards the elemental sulfur is not more than 15% lower than the selectivity in the absence of water. This definition of "Klaus-activity" core is but the Claus reaction, when reactions taking place in the direction of hydrogen sulfide and sulfur dioxide to elemental sulfur, the presence of water leads to the fact that part of the sulfur is again converted into hydrogen sulfide and sulfur dioxide. Hydrogen sulfide is then oxidized to the audience oxygen to sulfur and water vapor, then the "Klaus-active catalyst converts sulfur forth in its dioxide. As a result of these reactions, the catalyst exhibiting "Klaus-activity results in the presence of water to a sharp decrease in selectivity.

In the sense of the invention, the expression "the value of specific surface area" means the surface on BET. For the so-called measurement at three points used adsorption of nitrogen at 77 K. In the calculation of the surface area of the nitrogen molecule was taken as equal to 16.2 .

The average radius of the pores was determined based on a cylindrical model of the pores using the following formula:

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The value of pore volume, used in this formula, determined gravimetrically by saturating the pore water under vacuum.

The specific pore volume can also be determined by a mercury porosimetry at pressures up to 2000 bar. Data obtained by these two methods show good sooty little then too much that is, the risk of continued oxidation of sulfur to sulfur dioxide due to the fact that the sulfur remains in the pores too long, which is undesirable. However, the optimal radius then also depends on the size of catalyst particles. According to the invention requires the pore radius of at least 25 . This pore can be used, in particular, in cases when the size of the catalyst particles is quite small. An example of such cases is the use of powdered catalyst in a fluidized catalytic layer with a particle size in the range of 10 to 1 mm, or the use of a catalyst which caused such a layer on a carrier material, for example, of sintered metal or material with a honeycomb structure. In such cases, in General use a catalyst with a maximum pore 150 . The length of the pores in these cases can be kept small, for example, below the maximum of 100 .

According to another variant implementation of the invention, the catalyst consists of a flat, elongated or spherical particles with a diameter in the range of 1/32 to 1/2 inch (0.8 to 12.7 mm). Such catalysts are used preferably in reactors with a fixed layer, where the particle size is an important factor affecting the pressure drop in the reactor. That is at least 150 .

The average radius of the pores is preferably at least 50 to obtain the desired selectivity, more specifically, at least 200 , and when they use relatively large particles of catalyst, at least 325 , while 2000 is the upper limit. In General no additional benefits in excess of this limit is not achieved, while on the other hand may experience difficulties with the preparation of a carrier. More specifically, preferred is the average radius of pores of not more than 500 .

The catalyst according to the invention usually contain 0.1 to 10 wt. (of the total mass) of material which is catalytically active in the selective oxidation of hydrogen sulfide to elemental sulfur.

It should be emphasized that we are talking about the active material, which is available reaction gases. Indeed, during sintering or other methods of manufacture, the portion of the active material, in particular a metal oxide, may be encapsulated, for example, due to sintering of the narrow pores in the media. However, the difference between the encapsulated metal oxide and the metal oxide present on the media, can be easily installed Posada metal, present in the catalyst and is available for gas.

As an effective catalytically active material is used as a compound of a metal or mixture of metal compounds, possibly in combination with one or more compounds of nonmetals.

As catalytically active material is preferably used as a compound of iron or a compound of iron and chromium. Practically choose the molar ratio of Chromium/Iron less than 0.5 and preferably in the range of 0.02 to 0.3.

The catalyst according to the invention may contain promoters. Suitable promoters according to the invention are phosphorus compounds. These compounds can be applied, in particular by impregnation of the catalyst soluble compound of phosphorus.

Typically, the catalyst comprises a carrier material which is catalytically active material. It is also possible, however, the manufacture of a catalyst which does not contain a single material carrier, but the total mass which mainly consists of a catalytically active material. Preferably, however, use the carrier material which is catalytically active material.

The active component is present is utilizator.

Usually as a carrier used ceramic material, which under the reaction conditions does not show "Klaus-activity" or that was previously deactivated for this reaction. It is also possible, however, use as a carrier for other materials that exhibit zero or weak Klaus-activity meet the requirements of the average radius of the pores, and thermostable. Examples are thermostable ceramidase materials, such as structure type metal grid and the surface of the (imperfectly) sintered materials. Very suitable cell structure, which has a high thermal conductivity. Suitable materials for such media are different alloys of metals which are stable under the reaction conditions. Examples are metals such as iron, chromium, Nickel or alloys which include one or more of these metals.

The use of sintered metals or cellular structures as a structural material in the reactor, or as a material carrier, has advantages in that it enables you to effectively regulate the heat in the reactor. The fact that such materials make it easy to transfer heat that pozvoliavam layer. Can be used for applying only the catalytically active material or a catalytically active material together with the material carrier. In the latter case preferably applied a thin layer of catalyst. Then, the catalyst preferably has a relatively small radius of the pores, to obtain a sufficient quantity of the active surface. The specific surface of the catalyst should preferably be greater than 100 m2/, In this case, it is preferable to use a catalyst with a relatively short time, along with the length of the pores, for example, less than 100 m

As explained above, the aluminum oxide is generally unsuitable as a carrier. Found, however, that silicon dioxide, in which the pore radius and the specific surface satisfy the requirements set, gives good results when it is used as a carrier, so its use is preferred.

In principle, the catalysts according to the invention can be manufactured by the known methods of preparation of catalysts (applied).

Applied catalysts are preferably prepared (co) precipitation of the active component or components. When using more than one active components is to birati reaction conditions so that to the resulting material had the desired structure and properties or could be turned into such material.

Because the catalyst is preferably used with a material carrier, it is desirable to start with the fact that the media already had a suitable average radius of the pores and showed zero or minimal "Klaus-activity".

In order to bring the catalyst carrier in a suitable form, it can be previously subjected to processing by sintering.

If necessary, processing, sintering can be achieved on the finished catalyst, creating thus the micropores.

In the preparation of supported catalysts of the special care required by the operation of a homogeneous coating of catalytically active material on the carrier material, and in addition, must be provided for maintaining homogeneity during and after drying and calcination.

To meet these requirements very effectively prepare such catalysts "dry" impregnation of the material of the carrier with a solution of a precursor of the active component or components. This method is known under the name "method of pre-wetting". Good results organisations, increasing the viscosity, such as gidroxiatilzelluloza. By impregnation of the material of the carrier thus using the method of pre-wetting, obtain a catalyst in which an active material is applied very evenly.

The object of the invention is also a method of selective oxidation of serosoderjaschei compounds, in particular of hydrogen sulfide to elemental sulfur, using the catalyst according to the invention.

According to this method, hydrogen sulfide is oxidized directly to elemental sulfur by passing a gas containing hydrogen sulfide, together with a gas containing oxygen over a catalyst at elevated temperature.

It is noted that not only the structure of the catalyst, but also the process parameters determine the achievement of optimal results. The selected temperature and duration of contact for oxidation are of particular importance. With this in mind, the application of this catalyst allows tolerant of the excess oxygen and/or to the presence of water in the treated gas.

The oxidation process is carried out by adding such amount of oxygen or oxygen-containing gases, coderre oxygen to sulphur hydrogen must be between 0.5 and 5.0 and preferably between 0.5 and 1.5.

The method according to the invention is particularly suitable for the oxidation gas, which contains not more than 1.5% of hydrogen sulfide, because then can be used the normal adiabatic operating reactors.

When the oxidation temperature at the inlet to the catalytic layer is selected above 150oC and preferably above 170oC. This temperature is partly conditioned by the requirement that the temperature of the catalyst layer should be above the dew point temperature of the formed sulfur.

If you use fixed bed of catalyst particles, the particles preferably have a diameter in the range of 0.8 to 12.7 mm and the pore radius of at least 150 . For use in a fixed bed can also be used catalyst particles in the form of rings, discs, makaronipudding structures, hollow grains, etc., the Advantage is that they can be achieved with less pressure drop at the same height of the layer.

On the other hand, if you use a reactor with a fluidized bed, using the catalyst particles, which preferably have a diameter in the range from 10 m to 1 mm and the pore radius in the range of 25 to 150 .

One of the benefits generated by the use of the invention, prod sulfur. The invention also allows to significantly reduce the temperature of the reaction gases, because this catalyst has a lower temperature of initiation. Due to the exothermic nature of the oxidation reaction and the fact that too high a temperature may occur non-selective thermal oxidation of sulfur compounds, reducing the temperature of initiation is of great importance to increase the output of sulfur.

The temperature of the catalytic layer is usually kept lower than 330oC and preferably below 300oC known on its own activities.

If the content of hydrogen sulfide is higher than 1.5 on. it may be necessary to take measures to prevent excessive rise of temperature in the oxidation reactor, through the release of reaction heat. Such measures include, for example, the use of a cooled reactor, for example, a tubular reactor in which the catalyst is located within the tube is surrounded by a cooling agent. Such a reactor is known from the description of EPO N 91551. The reactor containing the cooling element can also be used for this purpose. In addition, you can return the processed gas to the inlet of the reactor after cooling. Thus doctorampicillin for many oxidation reactor, while simultaneously oxidizing the air is distributed over the various reactors.

In accordance with the private implementation of the method according to the invention, the catalyst used in the fluid in the reactor with a fluidized bed. Thus can be obtained optimum heat transfer.

According to another variant implementation, the catalyst is used in the form of a fixed layer, such as cell structures with high thermal conductivity, which is also well-prevents unwanted temperature rise of the catalyst.

The method according to the invention may be used with particular success for the selective oxidation of residual gases containing hydrogen sulfide, which are waste Klaus-plants".

In addition to the very high selectivity of the catalyst according to the invention, are a very important additional advantage in that it no longer requires removal of water prior to the oxidation process.

If method according to the invention is used for oxidation of the aforementioned residual gases, these gases are preferably first passed through a hydrogenation reactor which contains a catalyst is to of hydrogen sulfide.

According to a variant of the method according to the invention phase selective oxidation, which is used as a catalyst according to the invention, combined with the subsequent stage of hydrogenation, followed by the stage of absorption of hydrogen sulfide, as described in the application EPO N 71983. 98% of attendees sulfur compounds thus are removed in stages, prior to hydrogenation, so that the phase hydrogenation and absorption mass is not loaded excessively. Thus, it can be achieved percentage of sulfur recovery up to 100% Under option this way after stage hydrogenation may reapply selective oxidation according to the invention instead of using absorption is the percentage of the total recovery between sulfur and 99,5 99,8%

Further, the method according to the invention is particularly suitable for desulfurization, such as fuel gas, sewage gas, biogas, gas coke ovens, volatile substances from chemical enterprises, such as factories, and rayon gases burned in the gas and oil refineries.

If in the method according to the invention, a gas containing sulfur vapors coming from the stage selective oxidation, and preferably, after to the regular adsorption, the percentage recovery of sulfur limit increases to 100%

The invention is illustrated in the following examples. Values of the surface by BET and the average radius of the pores, referred to in these examples is defined by the methods defined above.

Example 1A.

100 g of silica (Degussa OH-50, C. E. T. 42 m2/g) is mixed with 147 g of water and 1.5 g SCE (hydroxyethylcellulose) and ekstragiruyut. The extrudate is dried at 100oC. To obtain a sufficient mechanical strength of the calcined extrudate at 700oC. Pre-formed carrier thus obtained has a surface according to BET of 45.5 m2/g, pore volume 0.8 cm3/g and average pore 350 A.

Example 1B.

0,44 g add (ethylenediaminetetraacetic acid) dissolved in 10% solution of ammonia to form a solution with pH 7. Then to this solution was added 0.52 g of Cr(NO3)39H2O and 2,05 g NH3Fe(edtc)1.5 H2O. the resulting slurry was adjusted to pH 6 25% ammonia solution and up to a volume of 8 ml with demineralised water. The result is a red solution.

10 g of extrudate obtained according to example 1A, impregnate then 8 ml of this solution. The extrudate is then dried for 5 hours UP>C in air for 5 hours generated phase of iron oxide/chromium oxide. The catalyst thus obtained has the largest surface 45,9 m2/g, pore volume 0.75 cm3/g and average pore 325 . The content of iron oxide is 4 wt. and chromium oxide to 1 wt. in the calculation of total weight of the catalyst.

Example 2.

2.58 g NH3Fe(edtc)1,5 H2dissolved in 3 ml of demineralized water. the pH of this solution is then 25% ammonia solution was adjusted to 6. In this solution, dissolve 0.10 g of diammoniumphosphate.

To the solution add demineralized water to a total volume of 8 ml Get red solution.

10 g of extrudate obtained according to example 1A, impregnated with 8 ml of this solution. The extrudate is dried for 5 hours at room temperature and 5 hours at 120oC. by Heating the sample for 5 hours in air to generate the phase of the iron oxide-oxygastra. The resulting catalyst has a value of the surface by BET 40,12 m2/g, pore volume to 0.72 cm3/g and average pore 350 .

The catalyst contains 5 wt. iron oxide, the phosphorus content is 0.5 wt. the rest of the media.

Examples 3 and 4.

Of the catalyst, Predoctoral tube diameter 8 mm fill 1 ml of this catalyst. Through the catalyst from the top down let the gas mixture with the following molar ratio: 4% O2, 1% H2S, 30% H2O in Not. Speed (N ml gas per ml of catalyst per hour) gas is 12,000 hours-1. The temperature was raised stepwise, 20oC 200oC to 300oC, and then reduced to 200oC. the Generated vapors condense sulfur to lower the output from the reactor at 130oC. remove Water vapor permeable membrane (Permapen"). The composition of the gas at the input and the output is determined by gas chromatography.

The experimental results are summarized in tables 1 to 3. These tables also present a comparison with the catalyst of example 1 from the description of U.S. patent N 4.818.740 (Sample A, table 1).

Examples 5 and 6.

Al203with a low value of the surface produced by the calcination of the extrudate g Al203at 1200oC. Specific surface area is 10 m2/g, pore volume of 0.6 cm3/g and average pore 1200 . SiO2with a low value of the surface prepared in example 1. for example, 1.

From this material the carrier receives the sieved fraction with a particle size between 0.4 and 0.6 mm Mini-reactor in the form of a quartz tube with a diameter of 8 m is: 0,5% SO2, 1% H2's Not. The rate of passage of gas is 12000 h-1and the temperature increase step, 20oC, from 200 to 300oC and back. Generated sulfur vapor condense on leaving the reactor at 130oC. the Composition of the incoming and outgoing gas determined by gas chromatography.

In table 4 the conversion of H2S (activity) expressed as a function of temperature.

Example 7.

2.58 g NH3Fe(edtc)1,5 H2O is dissolved in 3 ml of demineralized water. The solution is brought to pH 6 25% ammonia solution. In this solution, dissolve 0.10 g of diammoniumphosphate. To a total volume of 9 ml of the solution add demineralized water.

10 g of extrudate of silicon dioxide with a specific surface area of 126 m2/g is impregnated with 9.0 ml of the obtained solution. The extrudate is dried at room temperature for 5 hours and then at 120oC in the next 5 hours. By heating the dry sample in air at 500oC for 5 hours generate phase iron oxide/oxide of phosphorus. The so formed catalyst has the largest surface on BET 128,4 m2/g, pore volume of 0.87 cm3/g and average pore 140 . The catalyst contains 5% (weight is H2O is dissolved in 3 ml of demineralized water. The solution is brought to pH 6 25% ammonia solution. It dissolve 0.10 g of diammoniumphosphate. Demineralized water is added to the solution until the total volume of 7.4 ml.

10 g OF (Degussa) with a specific surface area of 180 m2/g are impregnated with 7.4 ml of this solution. The material is dried at room temperature for 5 hours and then at 120oC for a further 5 hours. By heating the sample at 500oC in air for 5 hours generate phase iron oxide/oxide of phosphorus. The so formed catalyst has a BET surface 182 m2/g, pore volume of 0.71 cm3/g and average pore 80 . The catalyst contains 5 wt. iron oxide, 0.56 wt. phosphorus, in the rest of the media.

The catalyst prepared according to examples 7 and 8, sieved, and the fraction of 0.4 to 0.6 mm in the amount of 1 ml injected into a quartz tube with a diameter of 8 mm

Down through the catalyst pass the mixture gas of the following composition: 0.5% of SO2, 1% H2's Not. The rate of passage of gas 12,000 h-1the temperature increase speed of 20oC 200oC to 300oC and back. The vapors condense sulfur at the outlet of the reactor at 130oC. With the version of H2S (activity) expressed as a function of temperature.

Example 9.

2.58 g NH3Fe(edtc)1,5 H2O is dissolved in 3 ml of demineralized water. the pH of the solution was adjusted to 6 with aqueous ammonia (25%). To this solution add 0,071 g of dihydrate of triacrylate and dissolve. To the solution add demineralized water to a total volume of 8 ml

10 g of extrudate obtained according to example 1A, impregnated with 8 ml of this solution. The extrudate is dried at room temperature for 5 hours, and then another 5 hours at 120oC. by Heating the dried sample at 500oC for 5 hours in air to generate the phase iron oxide-sodium oxide. The resulting catalyst has a value of the surface by BET 40,12 m2/g, pore volume to 0.72 cm3/g and average pore 350 . The catalyst contains 5 wt. iron oxide, 0.56 wt. sodium, the rest of the media.

In the same way as in example 3 determine the degree of conversion and selectivity. This demonstrates the unexpected effect of adding alkali metal to the catalyst according to the invention.

Example 10.

129 g NH4Fe(EDTA)for 1.5 H2O was dissolved in 160 ml of demineralized water. the solution pH was brought to 6 by adding ammonia solution (25%). In recip what emetrol 0.5 inch (1.2 cm) was soaked 510 ml. The paste was dried for seven hours at room temperature and for five hours at 120oC. obtained By heating the samples at 500oC in air for three hours on a medium silica obtained iron oxide. The catalyst had a specific surface area of 21.3 m2/g, pore volume of 1.03 cm3/g and an average pore diameter of 1080 . The content of iron oxide in the catalyst comprised by weight 5%

The quartz tube reactor with a diameter of 10 cm was filled with 510 ml of catalyst extrudates. Through the catalyst missed the gas mixture of the following molar ratios: 4% O2, 1% H2S, 30% H2O in Not. Volumetric gas flow (in NML per ml of catalyst per hour) was 4000 h-1. The temperature gradually at 20oC was increased from 200oC to 300oC, and then reduced to 200oC. a Pair allocated sulfur is condensed at a temperature of 130oC. the water vapor was removed with water-permeable membrane (Permapura). The composition of the incoming and outgoing gas was determined using a gas chromatograph. The results of the experiments are summarized in table.8.

Example 11.

5,16 g NH4Fe(EDTA)for 1.5 H2O was dissolved in 6.4 ml of demineralized water. the solution pH was brought to 6 by adding ammonia solution (2 the solution.

20 g of "Aerosil 380V" (Deggussa) was infused 30 ml. Thus obtained paste was dried for five hours at room temperature and for five hours at a temperature of 120oC. obtained By heating the samples at 500oC in air for three hours, the catalyst of silicon dioxide formed of iron oxide. The powder catalyst was sieved to obtain particles with a radius of 13 mm, the Catalyst had a specific surface area of 350 m2/g, pore volume of 0.6 cm3/g, average pore 32 Angstrom.

The quartz tube reactor with a diameter of 1.5 cm was filled with 5 ml of catalyst extrudates. Through the catalyst from the bottom up missed gas mixture of the following molar ratios: 4% O2, 1% H2S, 30% H2O in Not. Volumetric gas flow (in NML per ml of gas per hour) was 12000 h-1. With the high volumetric flow of the catalyst bed began to pseudogiants. The temperature was gradually increased to 20oC 200oC to 300oC, and then reduced to 200oC. a Pair allocated sulfur is condensed at a temperature of 130oC. the water vapor was removed with water-permeable membrane (Permapure). The composition of the incoming and outgoing gas was determined using a gas chromatograph. The results of the experience is intralesional water. To the solution add demineralized water to a total volume of 11 ml

10 g of extrudate obtained according to example 1A, is impregnated with this solution. The extrudate is dried at room temperature and at 120oC. and Then heat the sample at 500oC for 3 hours. The catalyst contains 5 wt. oxide of manganese.

Example 12B.

Of the catalyst prepared according to example 13A, prepare sieved fraction with a particle size between 0.4 and 0.6 mm Quartz reactor tube with a diameter of 8 mm fill 1 ml of this catalyst. Through the catalyst from the top down let the gas mixture with the following molar ratio: 5% O2, 1% H2S, 30% H2O in Not. Speed (N ml gas per ml of catalyst per hour) gas is 12,000 h-1. The temperature was raised stepwise, 20oC 200oC to 300oC and then reduced to 200oC. the Generated vapors condense sulfur to lower the output from the reactor at 125oC. the composition of the gas at the input and the output is determined by gas chromatography.

The experimental results are summarized in table 10.

Example 13A.

of 3.07 g Ni-salts of ethylenediaminetetraacetic acid are dissolved in 11 ml of demineralized water.

Example 13B.

The catalyst obtained in example 14a, was tested for catalytic activity.

The results are presented in table 11.

Example 14a.

0.24 g of Na3-citrate.2H2O was dissolved in demineralised water and brought to a volume of 11 ml of 10 g of extrudate silica was impregnated with this solution. The impregnated extrudate was dried at a temperature rising from room temperature from 120oC. Then progulivali at a temperature of 500oC for 3 hours. Thereafter, the calcined mass was infiltrated 11 ml 4,18 g citrate NH4-Fe in demineralised water, was dried and progulivali, as described above. Got a catalyst containing 5 wt. Fe2O3, 1 wt. sodium, the rest of the media.

Example 14b.

Screenings desired fraction of catalyst and test the catalytic activity was carried out as described in example 12B. The results are given in table 12.

Example 15A.

2,01 g add (ethylene-diamine-tetraoxane acid) and 2.00 g of Co(NO3)26H2O is dissolved in demi silicon impregnated with this solution. The impregnated extrudate is dried at a temperature of from room temperature to 120oC. and Then calcined at 500oC for 3 hours.

Get the catalyst containing 5.2 wt. Co3O4.

Example 15B.

Experience on the catalytic activity of the catalyst obtained in example E. the Results are shown in table 13.

1. Catalyst for the selective oxidation of sulfur compounds, particularly hydrogen sulfide containing catalytically active substance selected from the group of oxides of iron, chromium, manganese, cobalt and/or Nickel on a carrier of silica, characterized in that it has a specific surface according to BET of 20.1 350 m2/g, the average radius of the pores is equal to 32 2980 and contains from 1 to 10 wt. the specified active substance, the rest of the media.

2. The catalyst p. 1, characterized in that it further comprises a promoter from 0.05 to 1 wt. phosphorus compounds and/or sodium.

3. Process for the selective oxidation of sulfur compounds to elemental sulfur by contact of the gas mixture containing hydrogen sulfide, and oxygen-containing gas with a catalyst containing a catalytically active substance selected from the group of oxides: iron, chromium, manganese, côte specific surface according to BET of 20.1 350 m2/g, the average radius of the pores is equal to 32 1980 and contains from 1 to 10 wt. the specified active substance, the rest of the media.

4. The method according to p. 3, characterized in that the use of a catalyst which additionally contains as a promoter from 0.05 to 1 wt. phosphorus compounds and/or sodium.

Priority points:

31.10.89 on PP. 1 and 2;

21.07.89 on PP. 3 and 4.

 

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4 dwg, 1 tbl, 2 ex

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