DE2530674A1 - PROCESS FOR DESULFURIZATION OF GASES CONTAINING HYDROGEN SULFUR - Google Patents

Description

Process for the desulphurisation of hydrogen sulphide containing gas

Priority: July 11, 1974, France, no.74 24176

The present invention relates to desulfurization of containing low concentrations of hydrogen sulfide Gases by oxidation of the above hydrogen sulfide in sulfur,

A satisfactory process according to this reaction requires the highest possible degree of conversion of hydrogen sulfide, the greatest possible selection in order to avoid SO ^ formation ·, as well as a considerable Life of the catalytic converter,

The oxidation of H_S in S on Metallsulf is known iden at temperatures below 80 C, which is impossible is to treat gases containing large amounts of water vapor.

Oxidation of H_S on nickel, cobalt, molybdenum catalysts is also known, but freely higher

Temperatures that allow the conversion of H_S into S0 ".

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There is also the use of · activated carbon as a catalyst been proposed, however, this catalyst requires increased regeneration tempera doors, which additional Incurs costs (special steels).

The process according to the present invention has the advantage that gaseous mixtures with a high Content of water vapor at a sufficiently low Temperature (- / 200 C) can treat so that the resulting Sulfur remains absorbed on the porous catalyst in liquid or solid form; there is a shift of the thermodynamic equilibrium in the reactive Sense on. The catalyst fills up more and more with sulfur, which is why it is necessary to periodically use it To regenerate periods of time, i.e. to free it from sulfur and to isolate the latter.

The process according to the present invention for the desulfurization of low concentrations of hydrogen sulfide-containing gases consists in that, during a first period of time, the above-mentioned gases, mixed with oxygen, are passed over a catalyst, followed by a second period of time with the aid of a gas other than oxygen - At temperatures between 200 ° C and 500 ° C above mentioned catalyst, enriched with sulfur, rinses and is characterized in that the catalyst has a support with a large specific surface and a large effective pore volume and an active part consisting of an oxide and / or of salts, especially metal sulfides, wherein the temperature at which the gases coat the catalyst, between 8O ⁰ C and 200 C, preferably between 100 ° C and 170 ⁰ C, fluctuates.

The metals, the oxides and salts of which, in particular the sulfides, form the active part of the catalyst

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, Vanadium, chromium, iron, cobalt, nickel, copper, Molybdenum, silver and manganese.

In the preferred method according to the present invention the gases used have a weak concentration of hydrogen sulfide, in particular 0.2 l Vol .- / ö, similar to the effluent products of the defrosting systems of residual gases in which the CLAUS reaction occurs at a temperature between "room temperature and 180 ° C on a catalyst, such as activated aluminum oxide or Silica gel clay takes place.

With the different variants of the realization of the Process are the substances forming the carrier of the catalyst with a large specific surface and a large effective pore volume selected from the following products: alumina, alumina-silica gel, bauxite and zeolites.

In the different variants of the implementation of the process, the regeneration gas, such as nitrogen, methane, noble gases, water vapor, CO, SO ₂ , CS, COS (apart from oxygen) contains a reducing gas such as hydrogen sulfide, hydrogen or carbon monoxide.

In a preferred variant, the generation gas is formed by the gas to be treated.

In another variant, the regeneration gas is formed from the gas to be treated, mixed with 5 - 20 ⁰ Jo H "S".

In a special variant of the process, the active part of the catalyst contains 15-85% by weight of oxide and Manganese sulfide, with the remaining amount of the mentioned active Partly of salts but above all oxides and sulfides of transition metal, in particular of iron, nickel and Copper is formed.

This method is particularly good in the treatment of gaseous mixtures with a low content of HpS applicable because reaction is extremely exotic, and

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a sharp rise in temperature would, on the one hand, result in partial evaporation of the sulfur formed during the reaction, on the other hand a less selective oxidation of H_S for Consequence: one would produce much larger amounts of SO ,, obtain.

^{The following examples of the desulfurization 1} of gases containing hydrogen sulfide, which in no way limit the invention, give results which are obtained using various kinds of. . Catalysts were obtained under the conditions according to the invention.

EXAMPLE 1

A gas mixture of the following composition is passed over active alumina: 30% water vapor, 18% CO _p , 0.8% HS, 0.4% oxygen; the solid forms nitrogen. The contact time measured at 20 ° C and atmospheric pressure is 4 seconds. The temperature of the catalyst is in the range of 125-1 ^ 0 C, under these conditions the conversion of HgS into sulfur is only JOfo _t, whereby after a first regeneration by a gas mixture (10? O HS, 5 ^c / o CO, 3Ofo water vapor, the rest - nitrogen) at 300 ° the catalyst largely loses its activity: in a second purification the conversion of H _? It's only $ 30.

EXAMPLE 2 '

Purification is carried out analogously to the conditions of Example 1 on an alumina catalyst containing 19 ^c / ° tungsten and ^ ⁰ % nickel, but with an oxygen content of the treated gases of 0.6 %; the h_s is completely converted and the yield of sulfur is t 93f ° ^{to S0} 2 'Tf ⁰ * ^In contrast to ^the use of alumina no aging gene rat ion cycles occurs in the given case of the catalyst after 35 Tteinigungs- Re.

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EXAMPLE 3

When using an alumina-silica gel catalyst which contains 19 ^c / o V and 5 ^c / o Ni, results analogous to Example 2 are obtained.

EXAMPLE 4

Under the conditions of Example 1, but with an acid content of 0.5 / 0, an alumina catalyst containing 5% Ni is used. 92.fo HpS is converted into elemental sulfur. No aging of the catalyst can be observed after 19 cleaning regeneration cycles,

EXAMPLE 5

Under the conditions of Example 1, but with one Oxygen content of 2 ^, one works using a catalyst containing 5 / ό Co. One converts 9O / O of the HoS to sulfur. - *

EXAMPLE 6

Proceed as in the example above, but change the contact time, which is 1 second here. After 23 cleaning / regeneration cycles, the sulfur yield is 90o.

EXAMPLE 7

Under the conditions of Example 1, but with an oxygen content of 0.6% in the treated gases, an alumina catalyst containing ifo Ni is subjected to a treatment of 14 lieinic-xing regeneration cycles. After these 14 cycles, the conversion rate of H ₂ S is a sulfur 935ε at _a usbeute of 86.5 $.

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When using higher temperatures (18O C) the conversion of HpS $ 80, however, the sulfur yield exceeds 60 $ not, whereby 20 $ HpS are converted into S0 ".

EXAMPLE 8

The above example is followed, but with an oxygen content of $ 1 and a higher temperature (to 205 ° C), with the conversion of H_S 72 $ and the Seizure on S0 "makes 60 $.

EXAMPLE 9

Maintaining the conditions of Example 1, an active metal-based substance is used, containing $ 25 manganese, $ 10 iron, $ 1 nickel, $ 1 copper; the conversion of HpS is $ 82, the yield of Sulfur $ 80.

The inventive method is more accurate, however not described in a limiting sense using examples from the enclosed figures, with

in Fig. 1 a desulphurisation plant for industrial gas en with an extremely low content of HpS in only one step using the method according to the invention and

in Fig. 2 a desulfurization system from the same time Gas containing HpS and SOp shown in two stages is; in the first stage the wiping of active alumina gas · in the second stage the application of the method according to the invention.

In Fig. 1 is a system for desulphurization schematically a gas mixture with a low content of HpS shown.

The plant contains three columns ^1, 2 and 31 i 1 * those

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there is a catalyst consisting of metal oxide or salts with a porous substance as a carrier. The columns mentioned are regenerated as part of an uninterrupted permutation. In the following Description assumes that the columns 1 and are in the cleaning phase, the slide 4a, 4b, 5a, 5b, open, the slides 8a, 8b, 9a and 9b are closed while the column 3 ″ is in the regeneration phase, the slides 4c and 5c closed and the slides 8c and 9c are open.

The gas to be desulphurized reaches the system via a line 4 and penetrates columns 1 or 2, via the slides 4a and 4b. The gas to be desulphurized brushes the catalyst after it has been mixed with oxygen via the connecting pipes 20a and 20b, if necessary dissolved in an inert gas. thus pi ^ alctiscli in air, enriched by the exhaust gas flowing back via line 5 _; In columns 1 and 2, an economical oxidation of H ₂ S is carried out.

2 H ₀ S + O ₀ \ 2 S +2 H_0

2 2 • * - * ■ η 2

The sulfur formed is obtained as a precipitate on the catalyst, the purified gas leaves columns 1 and 2 through the line via slides 5a and 5h, respectively.

The line 5 contains a junction 21 through which a Part of the exhaust gas is sent back into columns 1 and 2 via the fan 22. Into the junction is a cooler 23, which reduces the temperature of the exhaust gas discharged in this way, interposed. A line 24 from the glass opens into the branch 21 25 incoming air. The lines 26, a, 26b and 26 c lead the gas from the discharge line 21 to the supply lines

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20a, 20b and 20c in each of the columns 1, 2 and 3.

If columns 1 and 2 are working on desulphurization, the slide 27a and 27b are open, the slide 27c closed. A controllable slide 28 makes it possible to determine the extraction of the exhaust gas coming from the fan 22, which is entrained by the air flow caused by the fan 25 will.

The inert regeneration grass moves in a closed circle. It is kept at an appropriate temperature between 200 ° and 35 ° ^C by indirect heat exchange in a furnace 6; it gets into the column via the slide 8c. The inert cold regeneration gas arriving in the column 3 causes desorption of the sulfur present as precipitate on the catalyst, as well as its transition to the vapor state by the inert gas mentioned above. At the outlet of the column 3, a gaseous product, consisting of a mixture of inert regeneration gas and sulfur vapor, flowing out through the line 9 via the slide valve 9c is captured. This effluent product is passed to a condenser 10, "which is kept at a temperature of approximately 125-135 ° C., with the aid of appropriate means, for example by circulating warm water or air, the sulfur condensing in the liquid state. The Liquid sulfur flows from the condenser through a line 12 into a container 14, where it is discharged if necessary and as required This gas then flows into a bubble separation system 13, where the bubble sulfur is separated, whereupon it is passed through line 15 via a fan 16 to a heating furnace 6 in order to be returned to the circuit.

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The regeneration of the adsorbent in the column 3 is completed by purging it to ensure that it is cooled. In addition, the slider ^{1 will be} yes. and 7 ^ closed, and the inert gas which was cooled during the condensation of the sulfur contained in it j is pressed by the fan 16 into the column 3 through the lines 17 and 8 via the slides 17a and 8c, which are then opened. At the end of the removal process, the slide 17a is closed, while the slide 7a and Jh are opened again; The subsequent fie generator ratio is then switched over via the regeneration gas circuit passed through the furnace, while the column to be regenerated is switched over via the gas circuit 4, 5 to be desulphurized.

One carries part of the inert one continuously Regeneration gas with the aid of a throttle valve 19a provided in the discharge line 19, wherein one at the same time a corresponding amount of generation gas initiates; this initiation is carried out by means of the throttle valve 18a, which is connected to the line 18 is accomplished. The line 18 can be used as a discharge to the column 4, which carries the gas to be desulfurized leads to be switched when the latter does not have oxygen contains.

In Fig. 2, a system for cleaning a gas mixture is shown schematically, which H "S and SO" in a molar ratio of H "s / SO over 2 contains. This system is particularly suitable for the treatment of residual sulfur gases in ¥ recognize working according to the CLAUS process suitable.

In this case, columns 1, 2 and 3 contain two catalyst beds arranged one above the other, which with

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1 ·, 2 ', 3' 1 ", 2" and 3 "are designated. In the first stages 1 ^J , 2 ', and 3'» one realizes the CLAUS ¹ reaction during the cleaning phase:

2 H ₂ S + SO ₂ ^ ₁ S _n + 2 H ₂ O

The resulting sulfur settles on -

the catalyst. The one from the first catalyst bed escaping gas only contains traces of SOp, but H_S in excess. It penetrates into the second Catalyst bed 1 ", 2" and 3 "after it has been enriched with oxygen through the feed lines 20a, 20b and 20c, which is diluted with an inert gas, i.e. in fact in air, enriched with exhaust gas via line 5 · With the _second Catalyst beds 1 ", 2" and 3 "are used to carry out the economical oxidation of hydrogen sulfide,

2 SH ₂ + O _{2 >} 2 S _n + 2 H ₂ O

¥ As stated above, the columns are in the frame regenerated according to a permutation sequence: two columns, e.g. columns 1 and 2 are working on purging operation, while the third column, e.g. column 3, is on regeneration is switched.

In this system, the regeneration gas consists partly of an effluent to be cleaned. This gas is introduced into the regeneration cycle through line 18. In this regeneration gas is hydrogen sulfide with initiated, the content of H "S in the regeneration gas being in the range of $ 5-20. How it works this system is identical to the one described above.

To complete the description of the invention The method follows a non-limiting example of the invention on an industrial scale. In this

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On a large-scale industrial plant, products flowing out from a sulfur factory are treated, as shown schematically in FIG. Each column has two beds ^: the first from 135 tons of activated alumina, the second 108 tons of alumina - containing 1 $ Nicke'l, two columns are connected to desulphurization, during runs in the third de ^r Me rat gene ionsvorhang.

At a throughput of 210,000 Nm3 / hour, a gas is allowed to flow into this system which, on average, in terms of volume has the following composition:

Hydrogen sulfide: 1

Sulfur anhydride 0 _f 50 $

Water vapor $ 33.00

Nitrogen '50, $ 14

CO ₂ $ 15.00

Bubble sulfur 6.00 g / Nm3

Residual gas from a Claus sulfur unit circulates through the entire column at a throughput of 105,000 Nm3 / hour.

The kest gas has a temperature when it enters the Columns from 130 C; the contact time with the first catalyst bed is 6 seconds TPN and 4 seconds on the second bed.

On the first catalyst bed, the CLAUS · 'see ! Reaction instead, on the second the economic one Oxidation of hydrogen sulphide into sulfur.

The feeding of all columns between the first and second catalyst bed with oxygen is at one Throughput of 1150 Nm3 / hour in air and 21,000 Nm3 / hour involved in exhaust gas.

The columns are switched every 15 hours. Each column is to be treated in one for 30 hours Residual gas flow switched on and 15 hours

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in a regeneration cycle, which is partially dependent on the CLAUS effluents to be cleaned, enriched with H "S, in order to have a content of H-S in the regeneration gas the order of magnitude of 10? £ is formed,

The gas circulates during the regeneration process through the two catalyst beds for about 10 hours at a temperature around 3 ° 0 C and then for 5 hours at 130 »at what temperature it emerges from the fan.

The exhaust gas obtained after passing through the first catalyst bed contains an average of 250 ppm sulfur anhydride and 4.100 ppm hydrogen sulfide,

The gas bed obtained after passing through the second catalyst bed contains an average of 272 ppm Sleeping hydrogen and 412 ppm sulfur anhydride j

The content of bubble sulfur is negligible. Under the operating conditions, the yield from residual gas cleaning remains pleasantly constant for hundreds Cleaning cycles.

When the amount of air pressed in between the two catalyst beds is doubled, the air escapes second catalyst bed only traces of H "S (less than 10 ppm), the SO2 content is 750 ppm.

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Claims (1)

PATENT CLAIMS 1, method of desulfurization of low concentrations of gases containing hydrogen sulfide, after which the above-mentioned in a first period of time passes oxygen-enriched gas over a catalyst and then flushes this sulfur-enriched catalyst in a second section with the aid of a gas other than oxygen> at a temperature between 200 C and 500 ° C.
characterized in that a catalyst is used as a carrier with a large specific surface area and a large effective pore volume, as well as one of an oxide and / or salts, especially metal sulfides. Existing active part disappears / ends, the temperature of the gas when brushing the catalyst being in the range of 80 C to 200 C, 2. The method according to claim 1, characterized in that g e mark e i without t that the metals, their oxides and salts, in particular the sulfides, the active part of the catalyst form especially tungsten, vanadium, chromium, iron, cobalt, nickel, copper, molybdenum, silver and Represent manganese, 3. Method according to claim 1, characterized in that ekennzeich.net, that the gases to be processed 509885/0936 , a low concentration of hydrogen sulfide, in particular of the order of 0.2 to 1 by volume -? o, having, similarly to the flowing products in plants for the desulphurisation of Pestgasen · in which the CLAUS ¹ see reaction at a temperature between. Room temperature 'and 180 on a catalyst, such as active, alumina or aluminum silicate takes place, H. Process according to Claim 1, characterized in that the substances with a large specific surface area and a large effective pore volume, which form the catalyst support, are selected between the following products: alumina, alumina-silica gel, bauxite, zeolites,. 5, method according to claim 1, characterized in that g e mark e.i chne t that the regeneration gas contains, besides oxygen, a reducing gas such as hydrogen sulphide, Hydrogen, CO, 6. The method according to claim 5, characterized in that the regeneration gas is formed by the gas to be treated. 7 »The method according to claim 6, characterized in that the regeneration gas from the gas to be treated. which is set with 5-2O ^c / o H "S, is formed. 509885/0936 8. Procedure according to. Claim 1,. thereby g ekennzei cnet that the active catalyst part
15-85% by weight 6 contains manganese oxide and manganese sulphide, the reading of the active part mentioned consists of salts, above all metal oxides and metal sulphides, in particular of iron, nickel and copper. 9 · method according to one of claims 1 - 8,
characterized in that the temperature of the gas mixed with oxygen is from 100 ° C to 170 ° C when the catalyst is bestx "calibrated. 509 8 8 5/0936