RU2359741C2 - Method of hydrogenous gas mixture cleaning from carbon oxide (versions) - Google Patents

Abstract

FIELD: treatment facilities.

SUBSTANCE: invention may be used for cleaning hydrogen-rich gas mixtures from carbon oxide. The process is divided into two stages, i.e at temperature no less than 90°C and pressure no less than 1 atm. At the first stage cleaning is performed by selective oxidation of carbon oxide by oxygen and/or air. At the second stage cleaning is performed by selective methanation of carbon oxide. According to the other version of invention, selective methanation may be conducted first, and selective oxidation of the residual carbon oxide may be conducted at the end. Copper and cerium oxide system is used as an active component of selective oxidation catalyst, whereas nickel and cerium oxide system is used an active component of selective methanation catalyst.

EFFECT: invention allows for improving effectiveness of hydrogenous gas mixtures cleaning from carbon oxide.

22 cl, 1 tbl, 8 ex

Description

The invention relates to a process for a catalytic method for purification of carbon monoxide from hydrogen-containing gas mixtures.

Hydrogen is one of the most important industrial gases and is widely used in the metallurgical, chemical, petrochemical and food industries. It is also supposed to be used in hydrogen energy, for example, as fuel for fuel cells. In this case, hydrogen can be obtained in a catalytic chemical process, for example, from various hydrocarbon feedstocks (gasoline, natural gas, alcohols, dimethyl ether, etc.). This hydrocarbon feedstock is converted into a hydrogen-containing gas mixture by steam and / or oxygen conversion and subsequent steam conversion of CO. Such a mixture usually consists of H ₂ , CO ₂ , N ₂ , H ₂ O and ~ 1 vol.% CO. It is known that carbon monoxide at a concentration of more than 0.001 vol.% (10 ppm) is a poison for the fuel electrode. Therefore, such a hydrogen-containing gas mixture must be cleaned of carbon monoxide before it is fed to the fuel cell.

One of the purification methods is purification by oxidation of carbon monoxide.

When carrying out such cleaning, the following reactions are possible:

2CO + O ₂ → 2CO ₂

2Н ₂ + О ₂ → 2Н ₂ О (gas)

In this case, the indicators of the efficiency of purification of hydrogen-containing gas mixtures from CO are the concentration of CO at the outlet of the reactor and oxygen selectivity, which is defined as the ratio of the amount of oxygen spent on the oxidation of CO to the amount of oxygen consumed by both reactions:

A known method (prototype) for the purification of hydrogen-containing gas mixtures from CO by oxidation with oxygen and / or air in two stages, and at least one catalyst layer can be used in both the first and second stages (RF No. 2211081, B01D 53 / 62, 08.27.2003).

In the first stage, highly selective catalysts based on copper and / or manganese are used, in which CuO-CeO ₂ and / or MnO ₂ -CeO ₂ with a content of CuO or MnO _{2 of} 1-10 wt.% Are used as an active component, and deposited on oxides of aluminum, zirconium, silicon, and / or compounds based on them, or on graphite-like carbon material.

In the second stage, noble metal catalysts are used that contain platinum, palladium, ruthenium, rhodium, iridium, mainly ruthenium and platinum supported on aluminum, zirconium, cerium, silicon and / or compounds based on them, or but on a graphite-like carbon carrier in an amount of not less than 0.01 wt.%, mainly 0.05-5.0 wt.%, as well as catalysts, the active component of which consists of mixtures, compounds or metal alloys (platinum, palladium, ruthenium, rhodium, rhenium, iridium koba ice, gold, copper, manganese, iron, etc.) containing two or more metals deposited on oxides of aluminum, zirconium, cerium, silicon and / or compounds based on them, as well as on graphite-like carbon material with a total metal content of at least 0.01 wt.%.

Each catalyst bed in both the first and second stages operates at different temperatures. Oxygen and / or air is fed into the reaction zone only in the first stage. The process is carried out at a molar ratio of oxygen to carbon monoxide present in the hydrogen-enriched gas mixture, from 0.5 to 3, at a temperature of at least 20 ° C, a pressure of at least 0.1 atm. The purified hydrogen-containing gas mixture contains at least 0.1 vol.% Carbon dioxide and at least 0.1 vol.% Water vapor.

The disadvantage of this method is the need to use noble metal catalysts in the second stage, as well as the fact that when air is used to conduct a selective CO oxidation reaction, a substantial dilution of the hydrogen-containing mixture with nitrogen occurs.

Another way to clean the gas mixture from carbon monoxide is the process of selective methanation of CO (US 2006/0111456 A1, C07C 27/06, 05/25/2006). Such purification proceeds by the reaction:

СО + 3Н ₂ → СН ₄ + Н ₂ О

Since three hydrogen molecules are consumed during CO methanation, it is advisable to carry out this process at low concentrations of carbon monoxide.

In addition, since carbon dioxide is also present in the mixture, it can also undergo methanation:

CO ₂ + 4H ₂ → CH ₄ + 2H ₂ O

CO ₂ in the mixture is present in a significantly higher concentration (~ 20-25 vol.% Than CO, therefore, in the event of this undesirable reaction, large losses of hydrogen are possible. The selectivity of the CO methanation process in the presence of CO ₂ in hydrogen-containing mixtures is equal to the ratio of the amount of CO converted in CH ₄ , to the total amount of methane formed in the methanation reactions of CO and CO ₂ :

Nevertheless, in comparison with the process of purification by selective oxidation of CO, the process of selective methanation is much simpler, since it does not require the introduction of oxygen / air into the reaction mixture (there is no significant dilution of the hydrogen-containing gas with nitrogen) and when using sufficiently selective and active catalysts, purify hydrogen-containing gas to a CO level below 10 ppm over a wider temperature range.

The problem to which the present invention is directed is to increase the efficiency of the process of purification of hydrogen-containing gas mixtures from CO to a level of less than 10 ppm: increase the selectivity of the process (or, which is the same, reduce the amount of hydrogen expended during the purification); a decrease in the amount of supplied air (oxygen), and, consequently, less dilution of the hydrogen-containing mixture with nitrogen; and the absence of noble metals in the catalysts to reduce their cost.

The problem is solved due to the process of purification of a hydrogen-containing gas mixture from carbon monoxide in two stages, and at least one catalyst layer can be used in both the first and second stages. At one stage, selective oxidation with oxygen and / or air is carried out, and at the other stage, selective methanation is carried out.

In this case, the first stage can be the stage of selective oxidation of carbon monoxide with oxygen and / or air, and the second stage can be selective methanation of carbon monoxide (the first option), or the first stage can be the stage of selective methanation of carbon monoxide, and the second stage can be selective oxidation of carbon monoxide and / or air (second option).

First option

The method of purification of a hydrogen-containing gas mixture from carbon monoxide is carried out in two stages at a temperature of at least 90 ° C and a pressure of at least 1 atm, purification in the first of the stages is carried out by selective oxidation of carbon monoxide with oxygen and / or air, and in the second stage by selective carbon monoxide methanation, a copper-cerium oxide system is used as an active component of a selective carbon monoxide oxidation catalyst, and p imenyayut nikeltserievuyu oxide system.

The process of selective CO oxidation is carried out using highly selective copper-based catalysts in which the copper-cerium oxide system with a copper content of at least 0.001 wt.%, Mainly 0.1-20 wt.% Both in bulk and applied, is used as the active component on various media and substrates. Ceramics, plastics, metals, composite materials, transition metal oxides, carbon material, etc. can be used as such carriers and substrates.

The process of selective CO methanation is carried out using highly selective nickel-based catalysts in which the nickel-cerium oxide system with a nickel content of at least 0.001 wt.%, Mainly 0.1-50 wt.% Both in bulk and applied is used as the active component on various media and substrates. Ceramics, plastics, metals, composite materials, transition metal oxides, carbon material, etc. can be used as such carriers and substrates.

The catalysts contain active components in an amount of not less than 0.01 wt.%.

Each catalyst bed in both the first and second stages can operate at different temperatures.

Oxygen and / or air in the reaction zone is fed to the stage of selective oxidation of carbon monoxide.

The purified hydrogen-containing gas mixture contains at least 0.001 vol.% Carbon dioxide.

The purified hydrogen-containing gas mixture may contain at least 0.001 vol.% Water vapor, at least 0.001 vol.% Nitrogen.

In the first and / or second stage, at least one catalyst bed may be used.

The process is carried out at a molar ratio of oxygen to carbon monoxide present in the hydrogen-rich gas mixture, close to the stoichiometric (O _{2 /} CO ~ 0.5-1), but not less than 0.01.

Second option

The method of purification of a hydrogen-containing gas mixture from carbon monoxide is carried out in two stages at a temperature of at least 90 ° C and a pressure of at least 1 atm, purification in the first of the stages is carried out by selective methanation of carbon monoxide, and in the second stage by selective oxidation of carbon monoxide with oxygen and / or air, a nickel cerium oxide system is used as an active component of a selective carbon monoxide catalyst, and as an active component of a selective carbon monoxide catalyst rimenyayut copper-cerium oxide system.

The process of selective CO methanation is carried out using highly selective nickel-based catalysts in which the nickel-cerium oxide system with a nickel content of at least 0.001 wt.%, Mainly 0.1-50 wt.% Both in bulk and applied is used as the active component on various media and substrates. Ceramics, plastics, metals, composite materials, transition metal oxides, carbon material, etc. can be used as such carriers and substrates.

The process of selective CO oxidation is carried out using highly selective copper-based catalysts in which the copper-cerium oxide system with a copper content of at least 0.001 wt.%, Mainly 0.1-20 wt.% Both in bulk and applied, is used as the active component on various media and substrates. As such carriers and substrates, ceramics, plastic, metals, composite materials, transition metal oxides, carbon material, etc. can be used.

The catalysts contain active components in an amount of not less than 0.01 wt.%.

The process is carried out at a molar ratio of oxygen to carbon monoxide present in the hydrogen-rich gas mixture, close to the stoichiometric (O _{2 /} CO ~ 0.5-1), but not less than 0.01.

Oxygen or air is fed into the reaction zone in a first step.

Oxygen or air in the reaction zone is fed to the stage of selective oxidation of carbon monoxide.

The purified hydrogen-containing gas mixture contains at least 0.001 vol.% Carbon dioxide.

The purified hydrogen-containing gas mixture may contain at least 0.001 vol.% Water vapor, at least 0.001 vol.% Nitrogen.

In the first and / or second stage, at least one catalyst bed may be used.

The essence of the invention is illustrated by the following examples.

The process of purification of hydrogen-containing gas mixtures from carbon monoxide is carried out in a flow reactor in two stages, each stage contains at least one catalyst layer. The reactor is a quartz tube with an inner diameter of 3 mm. Each catalyst bed contains from 0.3 to 1 g of catalyst. As catalysts for selective oxidation, copper-cerium oxide systems are used, massive or supported on a carrier. Nickel-cerium oxide systems, solid or supported on a support, are taken as selective methanation catalysts. The space velocity varies in the range of 1000-150000 h ^-1 , the temperature of the catalyst layers in the range of 90-400 ° C. The reaction is carried out in the pressure range of 1-10 atm. The reaction gas mixture has a composition, vol.%: 10 - 99.984 N ₂ , 0.001 - 50 CO ₂ , 0.01-2 CO, 0.005 - 1 O ₂ , 0 - 30 N ₂ O, 0 - 90 N ₂ .

Example 1

The purification of hydrogen-containing gas mixtures from carbon monoxide is carried out in a reactor in two stages with two catalyst layers. In the first stage with a single layer at a temperature of 210 ° C is an oxide copper-cerium catalyst containing 5 wt.% Cu. In the second stage with a single layer at a temperature of 290 ° C there is an oxide nickel-cerium catalyst containing 2.0 wt.% Ni. The reaction gas mixture consists of 1 vol.% CO, 0.5 vol.% O ₂ , 2 vol.% N ₂ , 66.5 vol.% H ₂ , 10 vol.% H ₂ O and 20 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 60,000 h ^-1 , to the second layer 30,000 h ^-1 ; the process is carried out at atmospheric pressure. The results are shown in the table.

Example 2

The purification of hydrogen-containing gas mixtures from carbon monoxide is carried out in a reactor in two stages with two catalyst layers. In the first stage with a single layer at a temperature of 180 ° C is deposited on Al ₂ About ₃ oxide copper-cerium catalyst containing 5 wt.% Cu. In the second stage with a single layer at a temperature of 280 ° C, a nickel-cerium oxide catalyst containing 2.0 wt.% Ni is deposited on a metal substrate. The reaction gas mixture consists of 1 vol.% CO, 0.5 vol.% O ₂ , 2 vol.% N ₂ , 73.5 vol.% H ₂ , 3 vol.% H ₂ O and 20 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 18000 h ^-1 , to the second layer 18000 h ^-1 ; the process is carried out at atmospheric pressure. The results are shown in the table.

Example 3. The purification of hydrogen-containing gas mixtures of carbon monoxide is carried out in a reactor in two stages with two catalyst layers. In the first stage with a single layer at a temperature of 180 ° C, there is an oxide copper-cerium catalyst containing 15 wt.% Cu. In the second stage with a single layer at a temperature of 280 ° C is supported on Al ₂ About ₃ oxide nickel-cerium catalyst containing 10.0 wt.% Ni. The reaction gas mixture consists of 1 vol.% CO, 0.5 vol.% O ₂ , 2 vol.% N ₂ , 73.5 vol.% H ₂ , 3 vol.% H ₂ O and 20 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 18000 h ^-1 , to the second layer 18000 h ^-1 ; the process is carried out at atmospheric pressure. The results are shown in the table.

Example 4. The purification of hydrogen-containing gas mixtures of carbon monoxide is carried out in a reactor in two stages with two catalyst layers. At the first stage, with a single layer at a temperature of 180 ° C, there is an oxide copper-cerium catalyst deposited on a metal substrate containing 5 wt.% Cu. In the second stage with a single layer at a temperature of 280 ° C there is an oxide nickel-cerium catalyst containing 5.0 wt.% Ni. The reaction gas mixture consists of 1 vol.% CO, 0.5 vol.% O ₂ , 2 vol.% N ₂ , 73.5 vol.% H ₂ , 3 vol.% H ₂ O and 20 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 18000 h ^-1 , to the second layer 30,000 h ^-1 ; the process is carried out at atmospheric pressure. The results are shown in the table.

Example 5

The purification of hydrogen-containing gas mixtures from carbon monoxide is carried out in a reactor in two stages with two catalyst layers. In the first stage with a single layer at a temperature of 250 ° C there is an oxide nickel-cerium catalyst containing 2.0 wt.% Ni. In the second stage with a single layer at a temperature of 190 ° C is an oxide of copper-cerium catalyst containing 5 wt.% Cu. The reaction gas mixture consists of 1 vol.% CO, 0.9 vol.% O ₂ , 68.1 vol.% H ₂ , 10 vol.% H ₂ O and 20 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 60,000 h ^-1 , to the second layer 6,000 h ^-1 ; the process is carried out at atmospheric pressure. The results are shown in the table.

Example 6

The purification of hydrogen-containing gas mixtures from carbon monoxide is carried out in a reactor in two stages with two catalyst layers. In the first stage with a single layer at a temperature of 90 ° C, there is an oxide copper-cerium catalyst containing 5 wt.% Cu. In the second stage with a single layer at a temperature of 230 ° C is an oxide of Nickel-cerium catalyst containing 10.0 wt.% Ni. The reaction gas mixture consists of 0.5 vol.% CO, 0.25 vol.% O ₂ , 1 vol.% N ₂ , 98.15 vol.% H ₂ and 0.1 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 10,000 h ^-1 , to the second layer 30,000 h ^-1 ; the process is carried out at a pressure of 10 atm. The results are shown in the table.

Example 7

The purification of hydrogen-containing gas mixtures from carbon monoxide is carried out in a reactor in two stages with two catalyst layers. In the first stage with a single layer at a temperature of 220 ° C, there is an oxide nickel-cerium catalyst containing 10.0 wt.% Ni. In the second stage with a single layer at a temperature of 90 ° C there is an oxide copper-cerium catalyst containing 5 wt.% Cu. The reaction gas mixture consists of 0.5 vol.% CO, 0.25 vol.% O ₂ , 1 vol.% N ₂ , 98.15 vol.% H ₂ and 0.1 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 30,000 h ^-1 , to the second layer 6,000 h ^-1 ; the process is carried out at a pressure of 10 atm. The results are shown in the table.

Example 8 (for comparison, the prototype)

The purification of hydrogen-containing gas mixtures from carbon monoxide is carried out in a reactor in two stages with two layers containing only selective CO oxidation catalysts. In the first layer at a temperature of 160 ° C is a catalyst containing 50 wt.% MnO ₂ -CeO ₂ . In the second layer at a temperature of 130 ° C, there is a catalyst containing 0.5 wt.% Ru-Pt / C. The reaction gas mixture consists of 1 vol.% CO, 1.15 vol.% O ₂ , 74.85 vol.% H ₂ , 3 vol.% H ₂ O and 20 vol.% CO ₂ . The volumetric feed rate of the reaction mixture to the first layer is 12000 h ^-1 , to the second layer 18000 h ^-1 ; the process is carried out at atmospheric pressure. The results are shown in the table.

The above examples demonstrate the high activity and selectivity of the proposed catalysts, which allows to effectively reduce the CO content in hydrogen-rich gas mixtures to a level below 10 ppm. The proposed catalysts have a wide possibility of varying their chemical composition. The proposed method and the use of the proposed catalysts can significantly increase the selectivity of the process, to avoid significant dilution of hydrogen-containing mixtures with nitrogen, and also to carry out the process without the use of noble metals in the catalysts.

Claims (22)

1. The method of purification of a hydrogen-containing gas mixture from carbon monoxide, which consists in carrying out the process in two stages at a temperature of at least 90 ° C and a pressure of at least 1 atm, characterized in that the purification in the first of the stages is carried out by selective oxidation of carbon monoxide with oxygen and / or air, and in the second stage by selective methanation of carbon monoxide, the copper-cerium oxide system is used as the active component of the catalyst for selective oxidation of carbon monoxide, and as the active component of catalysis To selectively carbonate methane, a nickel cerium oxide system is used. 2. The method according to claim 1, characterized in that the copper content in the active component of the catalysts for the selective oxidation of carbon monoxide is not less than 0.001 wt.%. 3. The method according to claim 1, characterized in that the nickel content in the active component of the catalysts for selective methanation of carbon monoxide is not less than 0.001 wt.%. 4. The method according to claim 1, characterized in that the active components of the catalysts of the first and / or second stage can be additionally deposited on a carrier. 5. The method according to claim 4, characterized in that the catalysts contain active components in an amount of not less than 0.01 wt.%. 6. The method according to claim 1, characterized in that the process is carried out at a molar ratio of oxygen to carbon monoxide present in the hydrogen-containing gas mixture, not less than 0.01. 7. The method according to claim 1, characterized in that oxygen or air in the reaction zone is fed to the stage of selective oxidation of carbon monoxide. 8. The method according to claim 1, characterized in that the hydrogen-containing gas mixture to be purified contains at least 0.001 vol.% Carbon dioxide. 9. The method according to claim 1, characterized in that the purified hydrogen-containing gas mixture may contain at least 0.001 vol.% Water vapor. 10. The method according to claim 1, characterized in that the purified hydrogen-containing gas mixture may contain at least 0.001% vol. Nitrogen. 11. The method according to claim 1, characterized in that at least one catalyst bed can be used in the first and / or second stage. 12. The method of purification of a hydrogen-containing gas mixture from carbon monoxide, which consists in carrying out the process in two stages at a temperature of at least 90 ° C and a pressure of at least 1 atm, characterized in that the purification in the first of the stages is carried out by selective methanation of carbon monoxide, and of the second stage by selective oxidation of carbon monoxide with oxygen and / or air, the nickel cerium oxide system is used as the active component of the catalyst for selective methanation of carbon monoxide, and the active component is cat A selective cerium oxide oxidation analyzer employs a copper-cerium oxide system. 13. The method according to p. 12, characterized in that the nickel content in the active component of the catalysts for selective methanation of carbon monoxide is not less than 0.001 wt.%. 14. The method according to p. 12, characterized in that the copper content in the active component of the catalysts for the selective oxidation of carbon monoxide is not less than 0.001 wt.%. 15. The method according to p. 12, characterized in that the active components of the catalysts of the first and / or second stage can be additionally deposited on a carrier. 16. The method according to clause 15, wherein the catalysts contain active components in an amount of not less than 0.01 wt.%. 17. The method according to p. 12, characterized in that the process is carried out at a molar ratio of oxygen to carbon monoxide present in the hydrogen-containing gas mixture, not less than 0.01. 18. The method according to item 12, wherein the oxygen or air in the reaction zone is fed to the stage of selective oxidation of carbon monoxide. 19. The method according to p. 12, characterized in that the purified hydrogen-containing gas mixture contains at least 0.001 vol.% Carbon dioxide. 20. The method according to p. 12, characterized in that the purified hydrogen-containing gas mixture may contain at least 0.001 vol.% Water vapor. 21. The method according to p. 12, characterized in that the purified hydrogen-containing gas mixture may contain at least 0.001 vol.% Nitrogen. 22. The method according to p. 12, characterized in that at least one catalyst bed may be used in the first and / or second stage.