KR20150103738A - Process for the production of synthesis gas from hard coal - Google Patents

Abstract

(a) dry pyrolyzing the alumina to produce a gas mixture containing hydrogen, methane, nitrogen and carbon monoxide as main components and carbon sulfide as a subcomponent, and (b) reacting the gas mixture with sulfur cobalt molybdenum (C) separating the hydrogen sulphide obtained from the hydrogenation from the gaseous mixture on the catalyst at a temperature in the range of 200 ° C to 280 ° C, and c) producing a synthesis gas from the coke.

Description

PROCESS FOR THE PRODUCTION OF SYNTHESIS GAS FROM HARD COAL [0002]

The present invention belongs to the technical field of making coke, and relates to a new method for removing carbon sulfide from coke oven gas and a new catalyst and its application.

The coke oven gas (synonym: coking gas) is obtained from the carburization of the wonder in a coke oven plant. As a major component, the gas typically comprises about 55 wt% hydrogen, 25 wt% methane, 10 wt% nitrogen, and 5 wt% carbon monoxide. Thus, although coke oven gas is generally qualified as a syngas for chemical reactions, it disadvantageously comprises carbonyl sulfide and carbon disulfide, for example, the carbonyl sulfide and disulfide carbon act as catalyst poisons in subsequent reactions It must be removed in advance. As a result, the catalysts often have to be cleaned or even exchanged, which involves direct effort and expense, and is also undesirable due to the turnaround of the plant.

One way to remove unwanted carbon sulphide from the coke oven gas is to catalytically hydrogenate the gas and convert the sulfur compound to hydrogen sulfide. These gases are also unwanted, but can easily be washed away by aqueous lye, for example ammonia solution.

Related methods are already known in the prior art. For example, German Patent Application DE 1545470 A1 (Pichler) suggests hydrogenating carbon sulfide on cobalt molybdenum, nickel molybdenum or nickel cobalt molybdenum catalyst with hydrogen sulphide, followed by separation of the hydrogen sulphide. In embodiments, the reaction temperature is above 550 < 0 > C.

The use of nickel, cobalt, molybdenum or palladium phase catalysts based on the hydrodesulfurization of coke oven gas is also known from various old Japanese patent applications such as JP 59 119 582 A2 (Shinnittetsu) or JP 59 230092 A1 (Hitachi) . These methods also

A similar method is also known from German Patent Application DE 2647690 A1 (Parsons), which discloses a catalyst-based sulfur-based catalyst system based on cobalt, molybdenum, iron, chromium, vanadium, thorium, nickel, tungsten and / Hydrogenating the retained carbon compound, and removing the hydrogen sulfide obtained in the extraction column with an alkali hydroxide solution. The sulfide of the metal is proposed as a concrete catalyst. However, also the disadvantage associated with this case is that the catalyst requires a temperature of at least 260 캜, and the hydrogenation preferably should be carried out at a significantly higher temperature, in part even above 400 캜. This is particularly undesirable for reasons of energy cost, and additionally such a temperature will change the composition of the gas, i.e. the methanation will already take place.

The prior art process has the practical disadvantage of converting the carbon sulfide into hydrogen sulfide in high yield and thus converting the coke oven gas into sufficiently high quality syngas, but all of these methods have to occur at very high temperatures, , Because otherwise an appropriate conversion rate would not be obtained.

It is therefore an object of the present invention to improve the existing process, if present, as long as the carbon sulphide and organosulfur compounds (e.g., thiophene) are converted at substantially lower temperatures, but substantially quantitatively to hydrogen sulfide. In addition, the process is intended to ensure that the mass ratio of carbon dioxide to methane is unchanged, i. E., To prevent methanation.

The subject of the present invention is

(a) The pyrolysis is dry-pyrolyzed to produce a gas mixture containing hydrogen, methane, nitrogen and carbon monoxide as main components and carbon sulfide as a sub ingredient,

(b) Gas mixture is hydrogenated over a sulfur cobalt molybdenum catalyst provided on an aluminum oxide carrier material at a temperature in the range of 200 ° C to 280 ° C,

(c) Separating hydrogen sulfide from hydrogenation from the gaseous mixture,

It is a method of producing synthesis gas from coke.

Surprisingly, the known sulfurous cobalt molybdenum catalysts for the hydrogenation of carbon sulfides exhibit characteristics that have high activity and selectivity even at less than 280 ° C, preferably less than 260 ° C, if the catalyst is deposited on the aluminum oxide carrier material . The carbon sulphide is actually hydrogenated with hydrogen sulphide to at least 95 vol.%, Without being affected by the hydrogenation to the ratio of carbon dioxide to methane. Considering the experience according to document DE 2647690 A1 cited in the introduction, it is believed that catalysts containing predominantly cobalt and molybdenum predominantly in the form of sulfides, particularly if the reaction is carried out under normal pressure, also promote ignorable methanation This is an unexpected result.

Creation of caulking gas by pyrolysis of wonder

During the carburization or pyrolysis of the wax occurring at 900 ° C to 1400 ° C, the volatile components of coal are released to form porous cokes, which now contain essentially only carbon. By fractional condensation, the raw gas is decomposed into tar, sulfuric acid, ammonia, naphthalene, benzene and so-called caulking gas. The caulking gas consists of hydrogen, methane, nitrogen and carbon oxide and can be used for further chemical reactions after appropriate treatment to obtain synthesis gas.

Hydrogenation process

Hydrogenation of the pyrolysis gas can be done in a customary manner, mainly fixed bed reactors have proved to be the most suitable because the catalyst is provided in the form of lumps as bulk layers or fixed packings. An embodiment is preferred in which the catalyst is arranged in the inner packings of the reactor, since the bulk material more easily results in channeling and therefore non-homogeneous flow distribution.

However, the advantage of hydrogenation in a fixed-bed reactor is that a high space / time yield can be obtained, which means that the process according to the invention is also advantageous in the range of about 500 l / h to about 1500 l / h, preferably about 1000 l / Gt; < RTI ID = 0.0 > l / h. ≪ / RTI > Preferably, the reactants, i. E. Pyrolysis gas and hydrogen, are co-introduced at the bottom of the reactor and pass through the catalyst bed leading to hydrogenation and leaving the reactor as product at the top, Advantages are provided.

As already mentioned in the introduction, a particular advantage of the process is that the sulfur compound is hydrogenated over the catalyst used according to the invention, allowing the reaction to be carried out under considerably milder conditions and the complete conversion of the carbon sulphide without any sign of methanation . The reaction temperature is in the range of 200 占 폚 to 280 占 폚, and preferably in the range of 240 占 폚 to 260 占 폚 with respect to the appropriate reaction rate. The reactor can be heated from the outside, resulting from higher energy consumption, or it can be heated before the reaction components are introduced into the reactor, where the mixing can take place, for example, in a nozzle operated by the Venturi principle have.

In addition, the reaction can occur in the range of 1 bar to 15 bar, i.e. at atmospheric pressure or below atmospheric pressure. Embodiments using pressures in the range of about 5 bar to about 10 bar are preferred because such pressures are advantageous for yield and reaction rate.

catalyst

Sulfur Cobalt Molybdenum Catalyst

The term " sulfur cobalt molybdenum catalyst " refers to a catalyst mainly containing molybdenum sulfide as an active catalyst and containing cobalt as a promoter. This type of catalyst is produced in a known manner by the simultaneous sulfidation of reactive oxides, where MoO3 is completely converted to MoS2. When MoS2 is applied to an aluminum oxide carrier, it is flatly bonded to the surface ('base bond') or bonded to only one edge ('edge bond'). After sulphiding, cobalt is available in three forms: Co9S8 crystals deposited first on the support, as Co2 + ions ('CoMo phase') on the edges of MoS2 plates and as Co2 + ions on tetrahedral sites in the aluminum oxide lattice. The preferred catalyst therefore consists predominantly of molybdenum sulphide, i.e. more than 50 mol%, preferably more than 70 mol%, most preferably more than 90 mol% of molybdenum sulfide and contains cobalt in the form of a sulfur as a promoter, The amount (unit: mol%) is given as a difference of 100. From this it is concluded that in a similar preferred embodiment the catalyst does not contain any other metals, and in particular does not contain any other transition metals.

Aluminum oxide carrier

Particularly high specific surface area aluminum oxide is considered as a suitable carrier for the sulfurous cobalt molybdenum catalyst and aluminum oxide preferably has the following characteristics:

- Minimum V37A: 75 ml / 100 g, preferably 80 ml / 100 g, most preferably 85 ml / 100 g;

- Maximum V0.1 μm: 31 ml / 100 g, preferably 25 ml / 100 g, most preferably 15 ml / 100 gM;

- Maximum V0.2 μm: 20 ml / 100 g, preferably 15 ml / 100 g, most preferably 10 ml / 100 g; And

- Ratio of V0.1 μm to V0.2 μm: at least 1.5.

Aluminum oxide supports of the type mentioned are well known from the state of the art. For example, European Patent Publication Nos. 1385786 B1 and EP 1385787 B1 (Axens) describe a process for preparing the above carrier wherein the hydrazilite type aluminum oxide is pulverized and treated with an aqueous solution of aluminum nitrate and formic acid in an amount of 200 After hydrothermal treatment for 6 hours at < RTI ID = 0.0 > 0 C, < / RTI > the resulting product is calcined at 400-1300. The carrier material is then extruded and ready for loading. As far as the nature and preparation of the catalyst carrier is concerned, the two mentioned references are incorporated by reference.

refine

The hydrogenation product leaving the reactor, particularly the fixed bed reactor, now contains the sulfur compound in the form of hydrogen sulphide, and the content is typically in the range of 50 ppm to 300 ppm. The presence of H 2 S is not as desirable as the presence of carbon sulfide alone, but in contrast to carbon sulfide, hydrogen sulfide can be cleaned relatively easily, most of all, by quantitative cleaning. For this purpose, the hydrogen gas preferably passes through the absorption column, where it is treated, for example, in a countercurrent with an aqueous base such as caustic soda or ammonia. Alternatively, other devices may be used for purifying the gas, for example as a venturi scrubber.

When the H2S moiety is separated, the purified product is available without restriction as a high quality syngas for further chemical reaction.

Industrial availability

Another subject of the present invention is the use of a sulfur cobalt molybdenum catalyst provided on an aluminum oxide carrier for the hydrogenation of carbon sulfide to hydrogen sulfide. To this end, such a cobalt molybdenum catalyst, which consists primarily of molybdenum sulphide and contains cobalt sulphide as the sole promoter, is preferably used for the metal component.

In addition, as the carrier for the cobalt molybdenum catalyst, aluminum oxide having a high specific surface area and having the following characteristics is preferable:

(i) Minimum V37A: 75 ml / 100 g, preferably 80 ml / 100 g, most preferably 85 ml / 100 g;

(ii) Maximum V0.1 μm: 31 ml / 100 g, preferably 25 ml / 100 g, most preferably 15 ml / 100 gM;

(iii)  Maximum V0.2 μm: 20 ml / 100 g, preferably 15 ml / 100 g, most preferably 10 ml / 100 g; And

(iv) Ratio of V0.1 μm to V0.2 μm: at least 1.5.

The present invention also encompasses a process for preparing hydrogen sulphide, wherein the hydrogen sulphide is hydrogenated in the presence of the amount of action of the sulfur cobalt molybdenum catalyst provided on the aluminum oxide carrier.

Preferably, the metal sulfide is hydrogenated in the presence of a cobalt molybdenum catalyst, predominantly consisting of molybdenum sulphide and containing cobalt sulphide as the only promoter. Also preferred are aluminum oxide supports which satisfy the following characteristics:

(i) Minimum V37A: at least 75 ml / 100 g, preferably 80 ml / 100 g, most preferably 85 ml / 100 g;

(ii) Maximum V0.1 μm: 31 ml / 100 g, preferably 25 ml / 100 g, most preferably 15 ml / 100 gM;

(iii) Maximum V0.2 μm: 20 ml / 100 g, preferably 15 ml / 100 g, most preferably 10 ml / 100 g; And

(iv) Ratio of V0.1 μm to V0.2 μm: at least 1.5.

Example

Example 1

A pilot plant for a fixed bed hydrogenation was equipped with a bulk layer of a commercially available massive cobalt molybdenum catalyst on an aluminum oxide carrier. A different coking gas was then introduced into the bottom of the column. The only difference between these so-called feed gases was the amount of carbon sulphide, in particular carbon disulphide. The hydrogenation was carried out at a temperature of 220 ° C and a pressure of 10 bar. The GHSV was about 1200 l / h.

The product gas was analyzed by gas chromatography with respect to sulfur, and the fraction of hydrogen sulfide and carbon sulfide was determined by the residence time. Table 1 summarizes the results. The conversion rate represents the hydrogenation of the CS2 fraction.

Hydrogenation results (weight, expressed in vol%, unless otherwise indicated)

The test results indicate that the fraction of carbon sulfide is at least 95% converted to hydrogen sulfide. At the same time, the proportion of other components in the coke oven gas remained constant and no specific methanation was observed.

Claims (18)

(a) dry pyrolysis of the alumina to produce a gas mixture containing hydrogen, methane, nitrogen and carbon monoxide as main components and carbon sulfide as subcomponents,
(b) hydrogenating the gas mixture on a cobalt molybdenum catalyst with a sulfur content on the aluminum oxide carrier material at a temperature in the range from 200 ° C to 280 ° C,
(c) separating hydrogen sulfide from hydrogenation from the gas mixture,
A method for producing syngas from coke. The process according to claim 1, wherein a synthesis gas having a content of carbon sulfide of from 10 ppm to 200 ppm is used. 2. The process of claim 1, wherein the hydrogenation is carried out at a temperature in the range of 240 < 0 > C to 260 < 0 > C. The process according to claim 1, wherein the hydrogenation is carried out at a pressure of from 1 bar to 15 bar. 5. The process according to claim 4, wherein the hydrogenation is carried out at a pressure of from 5 bar to 10 bar. The process according to claim 1, wherein the hydrogenation is carried out at a GHSV of 500 l / h to 1500 l / h. The process according to claim 1, wherein a cobalt molybdenum catalyst free of any other transition metal is used. The process according to claim 1, wherein a cobalt molybdenum catalyst mainly composed of molybdenum sulphide and containing cobalt sulfide as the only promoter is used for the metal component. The method of claim 1, wherein high specific surface area aluminum oxide is used as a carrier for a cobalt molybdenum catalyst, said aluminum oxide having the following characteristics:
(i) minimum V37A: at least 75 ml / 100 g, preferably 80 ml / 100 g, most preferably 85 ml / 100 g;
(ii) a maximum V0.1 μm: 31 ml / 100 g, preferably 25 ml / 100 g, most preferably 15 ml / 100 gM;
(iii) maximum V0.2 μm: 20 ml / 100 g, preferably 15 ml / 100 g, most preferably 10 ml / 100 g; And
(iv) Ratio of V0.1 μm to V0.2 μm: at least 1.5. 10. A process according to any one of claims 1 to 9, characterized in that the hydrogenation is carried out in a fixed-bed reactor. The method of claim 1, wherein the catalyst used in the fixed bed reactor is provided as a bulk layer or packing. 2. The process of claim 1, wherein after removal of the reactor, the hydrogenation product passes through an absorption column, wherein the hydrogen sulfide is washed away by a basic liquid. Use of a sulfur cobalt molybdenum catalyst provided on an aluminum oxide carrier for hydrogenation of carbon sulfide to hydrogen sulfide. 14. The process according to claim 13, wherein the cobalt molybdenum catalyst mainly composed of molybdenum sulphide and containing cobalt sulfide as the only promoter is used for the metal component, 14. Use according to claim 13, wherein the aluminum oxide having a high specific surface area is used as a carrier for a cobalt molybdenum catalyst, said aluminum oxide satisfying the following characteristics:
(i) minimum V37A: at least 75 ml / 100 g, preferably 80 ml / 100 g, most preferably 85 ml / 100 g;
(ii) a maximum V0.1 μm: 31 ml / 100 g, preferably 25 ml / 100 g, most preferably 15 ml / 100 gM;
(iii) maximum V0.2 μm: 20 ml / 100 g, preferably 15 ml / 100 g, most preferably 10 ml / 100 g; And
(iv) Ratio of V0.1 μm to V0.2 μm: at least 1.5. Wherein the hydrogen sulfide is hydrogenated in the presence of an amount of a sulfur cobalt molybdenum catalyst provided on an aluminum oxide support. 17. The process according to claim 16, wherein the metal component is hydrogenated in the presence of a molybdenum cobalt catalyst comprising mainly molybdenum sulphide and containing cobalt sulfide as the only promoter. The method of claim 16, wherein the aluminum oxide carrier satisfies the following characteristics:
(i) minimum V37A: at least 75 ml / 100 g, preferably 80 ml / 100 g, most preferably 85 ml / 100 g;
(ii) a maximum V0.1 μm: 31 ml / 100 g, preferably 25 ml / 100 g, most preferably 15 ml / 100 gM;
(iii) maximum V0.2 μm: 20 ml / 100 g, preferably 15 ml / 100 g, most preferably 10 ml / 100 g; And
(iv) Ratio of V0.1 μm to V0.2 μm: at least 1.5.