JP2007254177A - Methanation process of carbon monoxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient process for removing carbon monoxide, which is easy to control its reaction temperature and does not generate a run away reaction. <P>SOLUTION: A methanation process of carbon monoxide comprises bringing a catalyst for carbon monoxide methanation into contact with a hydrogen gas containing carbon monoxide gas, wherein a first reactor is connected with a second reactor, the reaction temperature (T<SB>1</SB>) of the first reactor is in the range of 170-250°C, the reaction temperature (T<SB>2</SB>) of the second reactor is in the range of 100-170°C and the reaction temperature difference (T<SB>1</SB>)-(T<SB>2</SB>) is in the range of 20-150°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for removing carbon monoxide in a hydrogen-containing gas. More specifically, a first reactor in which a high-temperature hydrogen-containing gas generated by the shift reaction is filled with a catalyst having a high activity at a relatively high temperature and a second reactor filled with a catalyst having a high activity at a relatively low temperature are connected in series. The present invention relates to an efficient method for removing carbon monoxide using a reaction apparatus connected to a reactor.

In recent years, power generation using fuel cells has been attracting attention because of its low pollution and low energy loss, and research and development for practical use is being promoted.
Various types of fuel cells are known, depending on the type of fuel and electrolyte, operating temperature, etc. Among them, hydrogen-oxygen using hydrogen as a reducing agent (active material) and oxygen or air or the like as an oxidizing agent. The development of fuel cells (low temperature operation type fuel cells) is the most advanced.

  There are various types of hydrogen-oxygen fuel cells depending on the type of electrolyte, the type of electrodes, and the like, and typical examples include phosphoric acid fuel cells and solid polymer fuel cells. In such fuel cells, platinum catalysts are often used for electrodes. However, platinum used in the electrode is easily poisoned by carbon monoxide (hereinafter also referred to as CO). Therefore, if the fuel contains more than a certain level of CO, the power generation performance may be reduced or depending on the concentration. There is a serious problem that power generation becomes impossible.

The deterioration of the activity of the catalyst due to CO poisoning is particularly remarkable at low temperatures, and this problem becomes particularly serious in the case of a low temperature operation type fuel cell.
Therefore, pure hydrogen is preferable as a fuel for a fuel cell using such a platinum-based electrode catalyst. However, from a practical point of view, it is inexpensive and has excellent storage properties or is already equipped with a public supply system. Fuel, for example, methane, natural gas (LNG), petroleum gas (LPG) such as propane, butane, various hydrocarbon fuels such as naphtha, gasoline, kerosene, light oil, alcohol fuel such as methanol, city gas, It has become common to use hydrogen-containing gas obtained by steam reforming of other fuels for hydrogen production or the like, and fuel cell power generation systems incorporating such reforming equipment are being promoted. However, since these reformed gases generally contain a considerable concentration of CO in addition to hydrogen, this CO is converted into a harmless to the platinum-based electrode catalyst, and the CO concentration in the fuel is reduced. There is a strong demand for the development of technologies that can be used.

For example, in a polymer electrolyte fuel cell, it is desirable to reduce the CO concentration to a low concentration of usually 100 ppm by volume or less, preferably 50 ppm by volume or less, more preferably 10 ppm by volume or less. In order to solve the above problem, as one of means for reducing the concentration of CO in the fuel gas (hydrogen-containing gas in the reformed gas), a shift reaction represented by the following formula (1) (water gas shift) A technique using reaction) has been proposed.
_{CO + H 2 O = CO 2} + H 2 (1)
However, in the reaction using only this shift reaction, there is a limit to the reduction of the CO concentration due to restrictions on chemical equilibrium, and it is generally difficult to reduce the CO concentration to 1% or less. Therefore, as a means for reducing the CO concentration to a lower concentration, a method has been proposed in which oxygen or an oxygen-containing gas (air or the like) is introduced into the reformed gas and CO is converted to CO ₂ . However, in this case, since a large amount of hydrogen is present in the reformed gas, hydrogen is also oxidized when attempting to oxidize CO, resulting in loss of hydrogen and insufficient removal of CO.

Recently, a method of converting CO to methane by methanation with hydrogen (hereinafter also referred to as methanation) has been reviewed. For example, in JP-A-3-93602 (Patent Document 1) and JP-A-11-86892 (Patent Document 2), a catalyst (Ru / γ-alumina catalyst) in which Ru is supported on a γ-alumina carrier, A method of contacting hydrogen gas containing CO is disclosed. However, if the hydrogen gas contains carbon dioxide (CO ₂ ),
Carbon dioxide methanation, which is a side reaction, also occurs and hydrogen is consumed, which is undesirable. Therefore, it is desired to develop a catalyst having a high CO methanation reaction, which is the main reaction, and a high selectivity (less carbon dioxide methanation reaction).

In order to solve the above problems, a catalyst in which a Ru compound and an alkali metal compound and / or an alkaline earth metal compound are supported on an inorganic oxide carrier has been proposed (see JP 2002-068707 A and Patent Document 3). .
Japanese Patent Laid-Open No. 3-93602 JP-A-11-86892 JP 2002-068707 A

  However, the above-mentioned conventional catalysts, particularly in the case of a low temperature operation type fuel cell electrode catalyst, have problems such as insufficient activity and sometimes a rapid increase in reaction temperature due to runaway reaction.

  An object of the present invention is to provide an efficient method for removing carbon monoxide, which can easily adjust the reaction temperature and does not cause a runaway reaction.

  For this reason, as a result of intensive studies to solve the above problems, the present inventors have used a reaction apparatus in which a first reactor and a second reactor are connected in series, and the first reactor is active at a relatively high temperature. Using a reactor filled with a high catalyst and filled with a highly active catalyst at a relatively low temperature in the second reactor, the reaction temperature can be easily adjusted, and no runaway reaction occurs. The inventors have found that it can be removed and have completed the present invention.

The configuration of the present invention is as follows.
[1] In a carbon monoxide methanation method in which a catalyst for carbon monoxide methanation and a hydrogen gas containing carbon monoxide gas are brought into contact with each other, a reactor is connected to the first reactor and to the second reactor. Consisting of a vessel,
The reaction temperature (T ₁ ) of the first reactor is in the range of 170 to 250 ° C., the reaction temperature (T ₂ ) of the second reactor is in the range of 100 to 170 ° C.,
A carbon monoxide methanation method in which the reaction temperature difference (T ₁ ) − (T ₂ ) with the reaction temperature (T ₂ ) of the second reactor is in the range of 20 to 150 ° C.
[2] The CO concentration (CF _{2 CO 3} ) in the carbon monoxide gas-containing hydrogen gas supplied to the first reactor is in the range of 0.3 to 1.0 Vol%, and the _{CO in} the outlet gas of the first reactor CO concentration (C1 _CO ) is 5
Is in the range 00Ppm, methanation process of carbon monoxide CO concentration in the outlet gas of the second reactor (C2 _CO) is 10ppm or less [1].
[3] The carbon monoxide methanation catalyst used in the first reactor has the highest CO removal rate at a reaction temperature (T ₁ ) of 190 to 210 ° C., and the carbon monoxide methanation catalyst used in the second reactor Is a catalyst having the highest CO removal rate at a reaction temperature (T ₂ ) of 120 to 140 ° C. [1] or [2] carbon monoxide methanation method.
[4] The CO removal rate of the carbon monoxide methanation catalyst used in the first reactor is 95% or more, and the CO removal rate of the carbon monoxide methanation catalyst used in the second reactor is 98% or more. [1] to [3] Carbon monoxide methanation method.
[5] The carbon monoxide methanation catalyst used in the first reactor is a carbon monoxide methanation catalyst used in the first reactor is ZrO ₂ , CeO ₂ , NiO, CoO, Co ₃ O ₄ , It consists of one or more oxides or composite oxides selected from Fe ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , and SiO ₂ , and at least of alkali metal oxides, alkaline earth metal oxides, and rare earth metal oxides 1 type is included, and one or more metals selected from 4B group, 6A group, 7A group and 8 group are supported as required.
The carbon monoxide methanation catalyst used in the second reactor is one or more oxides selected from NiO, CoO, Co ₃ O ₄ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , TiO ₂ , and SiO ₂ , or [1] to [4] carbon monoxide methanation method in which one or more metals selected from Group 4B, Group 6A, Group 7A and Group 8 are supported on the composite oxide support.
[6] The group 4B metal is Sn, the group 6A metal is Mo, W, and the group 7A metal is M.
[1] to [5] carbon monoxide methanation method in which n, Re, and Group 8 metal are Ru, Pt, Pd, Ni, Fe, and Co.
[7] The amount of metal supported in the catalyst for carbon monoxide methanation used in the second reactor is 0.5.
[1] to [6] carbon monoxide methanation catalyst in the range of ˜15 wt%.
[8] The carbon monoxide methanation method according to [1] to [7], wherein Ru is contained as the metal, and the ratio of Ru in the supported metal is in the range of 20 to 90% by weight.
[9] The carbon monoxide methanation method of [1] to [8], wherein a CO adsorption tower filled with a CO adsorbent is connected to the second reactor.
[10] The CO adsorbent is made of zeolite on which one or more metals selected from Group 4B, Group 6A, Group 7A and Group 8 are supported, and the content of metal in the CO adsorbent is 0.5. [1] to [9] carbon monoxide methanation method in the range of ˜15 wt%.
[11] The carbon monoxide methanation method, wherein the zeolite is at least one selected from ZSM-5 type zeolite, mordenite type zeolite, faujasite type zeolite, and β zeolite.

  According to the present invention, a high temperature hydrogen-containing gas generated by the shift reaction is filled with a catalyst having a high activity at a relatively high temperature, and a second reactor is charged with a catalyst having a high activity at a relatively low temperature. An efficient method for removing carbon monoxide using a reactor connected in series can be provided.

Hereinafter, modes for carrying out the present invention will be described.
The carbon monoxide methanation method according to the present invention is a carbon monoxide methanation method in which a carbon monoxide methanation catalyst and a carbon monoxide gas-containing hydrogen gas are brought into contact with each other. A second reactor connected to one reactor, and a reaction temperature difference (T ₁ ) − (T between the reaction temperature (T ₁ ) of the first reactor and the reaction temperature (T ₂ ) of the second reactor. ₂ ) is in the range of 20 to 150 ° C.

Like this invention, it consists of a 1st reactor and the 2nd reactor connected in series with this 1st reactor, and adjustment of reaction temperature becomes easy by making both into different reaction temperature. At this time, the reaction temperature (T ₁ ) of the first reactor is preferably 170 to 250 ° C., more preferably 190 to 210 ° C., and the reaction temperature (T ₂ ) of the second reactor is 100 to 170. It is preferable that it exists in the range of 120 degreeC and 120-150 degreeC.

When the reaction temperature (T ₁ ) of the first reactor is low, sufficient performance cannot be obtained depending on the catalyst used in the first reactor, and a high concentration of CO is supplied to the second reactor. Reaction temperature (T ₁
) Is too high, CO ₂ methanation occurs simultaneously, hydrogen consumption is significant, and it is difficult to achieve the desired purpose.

Further, the reaction temperature of the reaction temperature (T ₁ ) of the first reactor and the reaction temperature (T ₂ ) of the _second reactor may be the same, but the reaction temperature difference (T ₁ ) − (T ₂ ). Is preferably in the range of 20 to 150 ° C, more preferably 40 to 80 ° C.

If the reaction temperature difference (T ₁ ) − (T ₂ ) is small, the CO concentration at the outlet of the second reactor may not be lowered sufficiently. Even if the reaction temperature difference (T ₁ ) − (T ₂ ) is too large, CO ₂ methanation is likely to occur in the first reactor, and the reaction temperature in the second reactor is too low to sufficiently reduce the CO concentration. There may not be.

  As the carbon monoxide gas-containing hydrogen gas supplied to the first reactor, a shift reaction product gas is usually used. The shift reaction product gas contains hydrogen gas, carbon monoxide gas, carbon dioxide gas, water vapor, and the like, and may contain methane.

The hydrogen gas concentration in the shift reaction product gas is approximately 71 to 89 vol%, the carbon monoxide gas concentration is 0.3 to 1.0 vol%, the carbon dioxide gas concentration is 10 to 25 vol%, and the methane gas concentration is 0 to 3.0 vol%. (Gas composition). Furthermore, it contains water vapor at a ratio of 20 vol% to 70 vol% with respect to the shift reaction product gas.

The temperature of the shift reaction product gas is 180 to 250 ° C., and the CO concentration (CF _{2 CO 3} ) in the gas is preferably in the range of 0.5 Vol% or less. When the CO concentration (CF _{2 CO 3} ) in the gas is too large, the amount of hydrogen consumed in association with the CO methanation reaction increases, and the amount of hydrogen consumed to supply the fuel cell increases.

The CO concentration (C1 _CO ) in the outlet gas of the first reactor is preferably 500 ppm or less, more preferably in the range of 100 ppm. If the CO concentration (C1 _{CO 2} ) in the outlet gas of the first reactor is too large, the CO concentration may not be sufficiently lowered due to the reaction in the second reactor.

Moreover, CO concentration in the outlet gas of the second reactor (C2 _CO) is 10ppm or less, and further preferably not 5ppm or less. When the CO concentration (C 2 _{CO 2} ) in the outlet gas of the second reactor is large, when the fuel cell is supplied, the CO concentration is high, and therefore there is a problem that the electrodes of the fuel cell are poisoned with CO in a short time.

The carbon monoxide methanation catalyst used in the first reactor in the present invention is a reaction temperature (T ₁ ) 190.
The catalyst has the highest CO removal rate at ˜210 ° C., and the CO removal rate at this time is preferably 95% or more. When such a catalyst is used in the first reactor, the CO concentration can be easily reduced to approximately 10 ppm or less in the second reactor.

In addition, the carbon monoxide methanation catalyst used in the second reactor is a reaction temperature (T ₂ ) of 120˜
The catalyst has the highest CO removal rate at 140 ° C., and the CO removal rate at this time is preferably 98% or more. When such a catalyst is used in the second reactor, the CO concentration can be easily reduced to approximately 10 ppm or less.

Incidentally, CO removal rate at this time, SV: 500~25,000h ^-1, feed gas composition: H ₂ concentration 75~80vol%, CO concentration 0.3~1.0vol%, CO ₂ concentration 10～25Vol% , C
It is a value obtained by changing the reaction temperature under the condition that the H ₄ concentration is 0 to 3.0 vol% and further the water vapor is contained in the raw material gas in an amount of 20 vol% to 70 vol%.

[Catalyst for carbon monoxide methanation used in the first reactor]
As a catalyst for carbon monoxide methanation used in the first reactor, one selected from ZrO ₂ , CeO ₂ , NiO, CoO, Co ₃ O ₄ , Fe ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , and SiO _2. It consists of the above oxide or composite oxide. In particular, a catalyst composed of a composite oxide can selectively perform a CO methanation reaction at a reaction temperature of 170 ° C. or higher. In particular, those having the highest CO removal rate at 190 to 210 ° C. as described above are preferable.

Such a catalyst composition includes alkali (earth) metal oxides and rare earth metal oxides. Examples of such metal oxides include Na ₂ O, K ₂ O, Li ₂ O, BeO, MgO,
Examples thereof include CaO, BaO, La ₂ O _{3 and the} like, and mixtures or composite oxides thereof. The content of the alkali metal oxide or the like in the catalyst is preferably 0.05 to 3% by weight, more preferably 0.1 to 2% by weight.

  If the content of alkali metal oxide or the like is small, the activity at a relatively high temperature becomes insufficient, and it is not suitable as a catalyst used in the first reactor. If the content of the alkali metal oxide or the like is too large, it becomes active at a high temperature, but the alkali metal oxide or the like tends to aggregate during use and the catalyst life is shortened.

The catalyst used in the first reactor may carry one or more metals selected from Group 4B, Group 6A, Group 7A, and Group 8 as necessary. The amount of supported metal is 2% by weight or less, preferably 1% by weight or less. .

[Catalyst for carbon monoxide methanation used in the second reactor]
The carbon monoxide methanation catalyst used in the second reactor is preferably formed by supporting one or more metals selected from Group 4B, Group 6A, Group 7A and Group 8 on a metal oxide support. Specifically, as the metal component, Sn as the group 4B metal, Mo, W as the group 6A metal, Re as the group 7A metal, Ru, Pt, Pd, Rh, Ni, Co as the group 8 metal And one or more metals selected from Ir and Ir are preferably used. The reason why each of the above metals is preferable is not clear, but in the case of Sn, it is conceivable to improve the activity by promoting the elimination of the carbon species adsorbed on Sn or another metal. In the case of Mo and W, it is considered that active hydrogen is generated by dissociative adsorption of H ₂ and promotes hydrogenation to improve the activity. In the case of Re, it is considered that the activity is improved by promoting the adsorption and desorption of carbon species to Re or other metals. In the case of Ru, Pt, Pd, Rh, Ni, and Co, it is considered that the activity is improved by dissociating and adsorbing CO and H ₂ .

Especially, it is preferable that a metal component is 1 or more types of metals chosen from 8 groups, and specifically, Ru, Pt, Pd, Rh, Ni, Co, Ir etc. are mentioned.
In particular, when Ru is contained as a metal component, the activity and selectivity at low temperatures are improved, and it is suitable as a component for the catalyst used in the second reactor.

At this time, the ratio of Ru in the metal component is preferably 20% by weight or more, more preferably 25% by weight or more as a metal.
When the ratio of Ru in the metal component is less than 20% by weight as a metal, the activity at the low temperature is low and the heat generated by the reaction is small, so the reactivity in the second reactor is lowered, and as a result, the CO concentration is sufficiently high. May not be reduced.

The supported amount of such a metal component is preferably in the range of 0.5 to 15% by weight, more preferably 1 to 10% by weight as a metal in the catalyst used in the second reactor.
When the supported amount of the metal component is less than 0.5% by weight in the catalyst, the activity and selectivity may be insufficient.
When the supported amount of the metal component exceeds 15% by weight in the catalyst, although the activity is high, the CO ₂ methanation reaction takes place, the selectivity is lowered, and as a result, the effect of removing CO becomes insufficient.

Examples of the metal oxide support component include NiO, CoO, Co ₃ O ₄ , ZrO ₂ , CeO ₂ , Al _2.
It is preferably made of one or more oxides selected from O ₃ , TiO ₂ , and SiO ₂ , particularly complex oxides. Specifically, ZrO ₂ —CoO, ZrO ₂ —NiO, ZrO ₂ —CeO ₂ , ZrO ₂ —
CoO—NiO, NiO—CoO, CoO—CeO ₂ , NiO—CoO—CeO ₂ , ZrO ₂ —N
iO—CoO—CeO ₂ , Al ₂ O ₃ —Co ₃ O ₄ , Al ₂ O ₃ —CeO ₂ —CoO, Al ₂ O ₃ —NiO, TiO ₂ —CoO, TiO ₂ —NiO, TiO ₂ —SiO ₂ — Examples thereof include Co ₃ O ₄ .

  Furthermore, when the composite oxide contains at least one of Ni and Co oxides in an amount of approximately 10% by weight or more, preferably 30% by weight or more, the activity and selectivity at a low temperature can be improved.

The content of the oxide and / or composite oxide in the catalyst used in the second reactor is preferably 85 to 99.5% by weight, more preferably 90 to 99% by weight.
CO Adsorbent In the carbon monoxide methanation method according to the present invention, a CO adsorption tower filled with a CO adsorbent is preferably connected to the second reactor.

The CO adsorbent is not particularly limited as long as it can adsorb CO in a gas containing H ₂ , H ₂ O, CO _{2 and the} like generated in the second reactor, but in the present invention, the CO adsorbent is not limited. The adsorbent is made of zeolite on which one or more metals selected from Group 4B, Group 6A, Group 7A and Group 8 are supported, and the content of metal in the CO adsorbent is 0.5 to 15% by weight. It is preferable to be in the range.

As the zeolite used for the CO adsorbent, one or more zeolites selected from ZSM-5 type zeolite, mordenite type zeolite, faujasite type zeolite, and β zeolite are preferably used. When faujasite type zeolite is used, the molar ratio of SiO ₂ to Al ₂ O ₃ constituting the framework (SiO ₂ / Al ₂ O ₃ ) is preferably 10 or more, more preferably 15 or more.

  Such a zeolite has a higher specific surface area than other inorganic oxides or composite oxides, and a metal-supported zeolite catalyst can be obtained by supporting metal ions by an ion exchange method and performing a reduction treatment. At this time, since the supported active ingredient is fine metal fine particles, the CO adsorption capacity is high and can be suitably used.

  As the metal component supported on the zeolite, Sn as the group 4B metal, Mo, W as the group 6A metal, Mn, Re as the group 7A metal, Ru, Pt, Rh, Pd as the group 8 metal One or more metals selected from Fe, Ni, Co and Ir are preferably used.

  The amount of the metal component supported is preferably in the range of 0.5 to 15% by weight, more preferably 1.0 to 10% by weight as a metal in the adsorbent. If the amount of supported metal is small, the CO adsorption capacity is small, the amount of supported metal is large, and the CO adsorption capacity does not increase further. Depending on the type of metal, the particle size of the supported metal may increase. The amount may decrease.

When a CO adsorption tower filled with such a CO adsorbent is connected, the CO gas remaining in the gas generated in the second reactor can be adsorbed, and therefore substantially does not contain CO gas. Hydrogen gas can be produced, and when such hydrogen gas is used in a fuel cell, poisoning of the electrode of the fuel cell can be suppressed, so that the fuel cell can be used for a long time.

  The adsorption tower used by connecting to the second reactor can also be used by connecting a plurality of adsorption towers in parallel. In this case, at least one adsorption tower is used for adsorption, and the other adsorption tower is regenerated and repeatedly used. Can be used continuously. A schematic diagram of such a reactor of the present invention is shown in FIG.

  Further, a water removing device may be provided between the second reactor and the adsorption tower. For example, by exchanging heat at the outlet gas of the second reactor at a temperature of −20 ° C. or less, trapping moisture, and suppressing the supply of moisture to the adsorption tower, the amount of CO adsorption increases, Can be used for a long time.

The metal-supported zeolite that can be suitably used for such an adsorbent is preferably prepared by the following production method.
A carbon monoxide adsorbent is obtained by absorbing the metal salt aqueous solution used as an active ingredient in the zeolite powder described above so that the metal content in the obtained adsorbent is within the above range, and then drying and reducing. Can do.

Alternatively, the zeolite powder may be dispersed in water, and a metal salt or a metal salt aqueous solution used as an active ingredient may be added to the zeolite powder, followed by heating and ion exchange as necessary. The amount of the metal salt used at this time is preferably in the range of 0.1 to 5 moles of metal salt when the number of moles of Al ₂ O _{3 in} the zeolite is 1. When the amount of metal salt used is less than 0.1 mol, the amount of metal ions ion-exchanged to zeolite is small, and sufficient adsorption performance may not be obtained. If the amount of metal salt used exceeds 5 moles, it is difficult to further increase the amount of metal ions that can be supported by ion exchange, and the economic efficiency decreases because the number of metal ions and metal complex ions that are not ion-exchanged increases. There's a problem.

The temperature at the time of ion exchange is usually from room temperature to 98 ° C., and the time is from 0.5 hours to 12 hours.
As the metal salt, the aforementioned metal salt is used.

A carbon monoxide adsorbent can be obtained by absorption after metal salt absorption or ion exchange, filtration, washing, drying, and reduction.
The drying conditions are not particularly limited, but are usually dried at 80 to 200 ° C. After drying, the catalyst for carbon monoxide methanation can be obtained by reducing at 100 to 700 ° C., preferably 150 to 600 ° C. in a reducing gas atmosphere.

As the reducing atmosphere gas, hydrogen gas or a mixed gas of hydrogen gas and inert gas such as nitrogen gas is usually used.
If the reduction temperature is low, the reduction is insufficient and sufficient adsorption performance may not be obtained. If the reduction temperature is high, the particle size of the supported metal may be too large, resulting in insufficient adsorption performance, or metal sintering may occur, resulting in insufficient adsorption performance.

Although the time for reduction varies depending on the temperature, it is usually 0.5 to 12 hours.
The adsorbent thus obtained can be used directly as a powder as an adsorbent, but is usually pulverized if necessary and molded as it is with a tablet molding machine, or a binder such as silica sol or alumina sol. Can be mixed and, if necessary, a molding aid can be mixed and molded by an extrusion molding machine. Further, an adsorbent layer may be formed on the honeycomb substrate.
[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.
[Example 1]
Preparation of methanation catalyst (1-1) for the first reactor 46.6 g of cobalt nitrate hexahydrate, aqueous zirconyl nitrate solution (ZrO ₂ concentration: 25%)
232.0 g and 109.0 g of nickel nitrate hexahydrate were added to 1240.5 g of water to prepare a mixed aqueous solution (1-1).
80.5 g of sodium hydroxide was dissolved in 1519.5 g of water, and a mixed aqueous solution (1-1) was added thereto while stirring to prepare a hydrogel, followed by aging at 80 ° C. for 2 hours.

The aged hydrogel was filtered, washed with sufficient warm water, and dried at 120 ° C. overnight. Further, a solution obtained by dissolving 12.7 g of magnesium nitrate hexahydrate in 48.0 g of water was absorbed into the dried product, dried at 120 ° C. for 5 hours, and then at 550 ° C. for 1 hour in the air. Firing is carried out at 400 ° C. under a hydrogen-nitrogen mixed gas (H ₂ concentration of 10 vol%) for 1 hour, and then the reduced composite oxide powder is filled into a tablet molding machine, and 50 kg / cm. The first reactor methanation catalyst (1-1) was prepared by press molding at ² , then pulverizing, and adjusting the particle size to 20 to 42 mesh. The active component, the content of each carrier component, the specific surface area and the pore volume were measured, and the results are shown in the table.
Preparation of catalyst for methanation (1-2) for second reactor 166.9 g of cobalt nitrate hexahydrate, zirconyl nitrate aqueous solution (ZrO ₂ concentration: 25%)
) 204.0 g and nickel nitrate hexahydrate 23.4 g were added to 1421.4 g of water to prepare a mixed aqueous solution (1-2). A hydrogel was prepared by dissolving 86.51 g of sodium hydroxide in 1489.4 g of water and adding the mixed aqueous solution (1-2) to this while stirring, and then aging at 80 ° C. for 2 hours. The aged hydrogel is filtered, washed with sufficient warm water, dried at 120 ° C. for one day, and then baked in the air at 550 ° C. for 1 hour, from cobalt oxide, nickel oxide, and zirconium oxide. A composite oxide powder was obtained.

The obtained complex oxide powder is filled into a tablet molding machine, pressure molded at 50 kg / cm ² , then pulverized, and the particle size is adjusted to 20 to 42 mesh to obtain a methanation catalyst carrier for the second reactor. It was.

50 g of the prepared methanation catalyst support for the second reactor absorbs 52.6 g of the impregnation solution in which ruthenium chloride is dissolved so that the metal concentration becomes 10% by weight, and is allowed to stand for 1 hour. Dry for 2 hours, then disperse in 2 L of sodium bicarbonate solution adjusted to pH 10-11, stir, then wash with sufficient warm water, dry at 120 ° C. for 5 hours, and at 550 ° C. Calcination in the atmosphere for 1 hour, and reduction treatment for 1 hour under the flow of hydrogen-nitrogen mixed gas (H ₂ concentration 10Vol%) at 400 ° C for the second reactor methanation catalyst (1-2)
Was prepared.

Preparation of adsorbent (1) 100 g of Y-type zeolite (SiO ₂ / Al ₂ O ₃ = 5 molar ratio) was suspended in 1900 g of water, and then heated to 60 ° C. to obtain an aqueous chloroplatinic acid solution (Pt concentration 2%). While stirring, 1120.0 g was added, and further maintained at 60 ° C. for 2 hours. Thereafter, it is filtered, washed with sufficient warm water, dried at 120 ° C. for one day and night, baked in the atmosphere at 450 ° C. for 3 hours, and mixed with hydrogen-nitrogen gas (H ₂ concentration 10 Vol% at 400 ° C.). ) Under the flow of 1), then filled into a tablet molding machine, pressure-molded at 50 Kg / cm ² , then pulverized, adjusted the particle size to 20-42 mesh, and adsorbent (1) Prepared.

Reaction test 4.2 ml of methanation catalyst (1-1) was charged into a stainless steel reaction tube (first reactor) having an inner diameter of 12 mm, and a hydrogen-nitrogen mixed gas (H) at a catalyst layer temperature of 400C. Then, after reducing again for 1 hour under the flow of ₂ concentration 10Vol%), the catalyst layer temperature was set to the reaction temperature of 210 ° C, and then the reaction mixed gas (carbon monoxide 0.6Vol%, carbon dioxide 20.0Vol%) , Methane 2.0 vol%, hydrogen 5
1.37 Vol% and water vapor 33.3 Vol%) are distributed so that SV = 2,000 h ^-1, and the product gas in a steady state after about 1 hour is analyzed by gas chromatography and an infrared spectroscopic gas concentration meter. The results of measuring the reaction tube outlet CO concentration are shown in the table.

Furthermore, 4.2 ml of methanation catalyst (1-2) was added to a stainless steel reaction tube (inner diameter of 12 mm).
The second reactor is charged and reduced again for 1 hour at a catalyst layer temperature of 400 ° C. under a hydrogen-nitrogen mixed gas (H ₂ concentration of 10 Vol%), and then the catalyst layer temperature is set to a reaction temperature of 130 ° C. After that, the gas produced in the first reactor was circulated so that SV = 2,000 h ^−1, and the produced gas in a steady state after about 1 hour was obtained by gas chromatography and an infrared spectroscopic gas concentration meter. The results of analysis and measurement of the reaction tube outlet CO concentration, CO ₂ concentration, and CH ₄ concentration are shown in the table. As the selectivity, the increase / decrease in CO ₂ from 20.0 Vol% of carbon dioxide in the reaction gas is shown in the table, and the case where the increase / decrease in CO ₂ is small is evaluated as being excellent in selectivity.

Furthermore, 8.4 ml of the adsorbent (1) was filled into a stainless steel reaction tube (adsorption tower) having an inner diameter of 12 mm, and again under a flow of hydrogen-nitrogen mixed gas (H ₂ concentration 10 Vol%) at an adsorbent layer temperature of 300 ° C. After reducing for 1 hour, and then setting the adsorbent layer temperature to 120 ° C., the gas produced in the second reactor was circulated so that SV = 1,000 h ^−1, and the outlet CO concentration after about 1 hour Table 1 shows the results of analyzing the CO concentration with an infrared spectroscopic gas concentration meter and measuring the CO concentration.
[Example 2]
In Reaction Test Example 1, the reaction was performed in the same manner except that the SV of the reaction in the first reactor was 4,000 h ⁻¹ , and the results are shown in the table.
[Example 3]
In Example 1, it carried out similarly except having performed the reaction temperature in a 1st reactor at 190 degreeC, and a result is shown to a table | surface.
[Example 4]
Preparation of methanation catalyst (2-1) for first reactor 204.0 g of aqueous zirconyl nitrate solution (ZrO ₂ concentration: 25%) and nickel nitrate 6
A mixed aqueous solution (2-1) was prepared by adding 116.8 g of hydrate, 3.56 g of lanthanum nitrate hexahydrate and 60.5 g of iron nitrate nonahydrate to 1300.0 g of water.
A hydrogel was prepared by dissolving 91.6 g of sodium hydroxide in 1621.5 g of water and adding the mixed aqueous solution (4) thereto while stirring, and then aging at 80 ° C. for 2 hours.

The aged hydrogel was filtered, washed with sufficient warm water, and dried at 120 ° C. overnight. Further, a solution obtained by dissolving 6.4 g of magnesium nitrate hexahydrate in 49.0 g of water was absorbed into the dried product, dried at 120 ° C. for 5 hours, and then at 550 ° C. for 1 hour in the air. Calcination is performed, and reduction treatment is performed for 1 hour at 400 ° C. under the flow of a hydrogen-nitrogen mixed gas (H ₂ concentration: 10 vol%). Then, the reduced composite oxide is filled in a tablet molding machine at 50 kg / cm ² . The first reactor methanation catalyst (2-1) was prepared by pressure molding, then pulverizing, and adjusting the particle size to 20 to 42 mesh. The active component, the content of each carrier component, the specific surface area and the pore volume were measured, and the results are shown in the table.
Preparation of catalyst for methanation (2-2) for second reactor Zirconyl nitrate solution (ZrO ₂ concentration: 25.0%) 168.00 g, cerium nitrate-6
A mixed aqueous solution (2-2) was prepared by dissolving 50.20 g of hydrate, 100.89 g of cobalt nitrate hexahydrate and 46.71 g of nickel nitrate hexahydrate in 2800 g of water.

A hydrogel slurry was prepared by dissolving 86.51 g of sodium hydroxide in 3200 g of water and adding the mixed aqueous solution (2-2) thereto while stirring, and then aging at 80 ° C. for 2 hours.
The aged hydrogel was filtered, washed with sufficient warm water, dried at 120 ° C. for 1 day, and then fired at 550 ° C. for 1 hour in the air to obtain a composite oxide powder. Subsequently, the complex oxide powder was filled in a tablet molding machine, pressure-molded at 50 kg / cm ² , pulverized, and the particle size was adjusted to 20 to 42 mesh to prepare a support for methanation catalyst.

18.13 g of an impregnation solution in which ruthenium chloride and palladium chloride were dissolved in 50 g of the obtained methanation catalyst so that the metal weight ratio was Ru: Pd = 1: 0.4 and the metal concentration was 10% by weight. The sample was allowed to stand for 1 hour, then dried at 120 ° C. for 8 hours, then dispersed in 2 L of sodium bicarbonate solution adjusted to pH 10 to 11 and stirred, and then sufficiently warm water was applied. Washed at 120 ° C. for 5 hours, fired at 550 ° C. for 1 hour in the atmosphere, and reduced at 400 ° C. for 1 hour under a flow of hydrogen-nitrogen mixed gas (H ₂ concentration 10 Vol%). Thus, a methanation catalyst (2-2) for the second reactor was prepared.

The active component, the content of each carrier component, the specific surface area and the pore volume were measured, and the results are shown in the table. Preparation of adsorbent (2) After suspending 100 g of Y-type zeolite (SiO ₂ / Al ₂ O ₃ = 5 mole ratio) in 1900 g of water, the mixture was heated to 60 ° C. to obtain an aqueous copper chloride solution (concentration of 2% by weight as Cu). ) 925.0 g was added and the mixture was further stirred at 60 ° C. for 2 hours. Thereafter, it is filtered, washed with sufficient warm water, dried at 120 ° C. for one day and night, baked in the atmosphere at 450 ° C. for 3 hours, and mixed with hydrogen-nitrogen gas (H ₂ concentration 10 Vol% at 400 ° C.). ) Under the flow of 1), then filled into a tablet molding machine, press-molded at 50 kg / cm ² , then pulverized, adjusted the particle size to 20-42 mesh, and adsorbent (2) Prepared.
In Example 1 of the reaction test , except that the methanation catalyst (2-1) was used in the first reactor, the methanation catalyst (2-2) was used in the second reactor, and the adsorbent (2) was used in the adsorption tower. The results are shown in the table.
[Example 5]
In Example 4, the same procedure was performed except that the SV in the first reactor was 4,000 h ⁻¹ , and the results are shown in the table.
[Example 6]
In Example 4, it carried out similarly except having made reaction temperature in a 1st reactor into 180 degreeC, and a result is shown to a table | surface.
[Example 7]
Preparation of first reactor methanation catalyst (3-1 ) 50 g of first reactor methanation catalyst (1-1) prepared in the same manner as in Example 1 was added to Ru.
After absorbing 25.13 g of an aqueous ruthenium chloride solution having a concentration of 1.0% by weight, the mixture was allowed to stand for 1 hour, dried at 120 ° C. for 8 hours, and then 2 L of a sodium hydrogen carbonate solution adjusted to a pH of 10 to 11 After being dispersed in and stirred, washed with sufficient warm water, dried at 120 ° C. for 5 hours and then reduced in a hydrogen stream at 400 ° C. for 1.5 hours to obtain a methanation catalyst. (3-1) was prepared. The active component, the content of each carrier component, the specific surface area and the pore volume were measured, and the results are shown in the table.
In Reaction Test Example 1, the same procedure was performed except that the methanation catalyst (3-1) was used in the first reactor, and the results are shown in the table.
[Example 8]
In Reaction Test Example 7, the reaction was conducted in the same manner except that the reaction temperature in the first reactor was 190 ° C., and the results are shown in the table.
[Comparative Example 1]
The same procedure as in Example 1 was performed except that the reaction temperature in the first reactor was 280 ° C. and the reaction temperature in the second reactor was 190 ° C.
[Comparative Example 2]
The same procedure as in Example 1 was performed except that the reaction temperature in the first reactor was 150 ° C. and the reaction temperature in the second reactor was 190 ° C.
[Comparative Example 3]
The same procedure as in Example 1 was performed except that the reaction temperature in the second reactor was 190 ° C. [Comparative Example 4]
The same procedure as in Example 1 was performed except that the reaction temperature in the first reactor was 150 ° C. [Comparative Example 5]
The same procedure as in Example 4 was performed except that the reaction temperature in the first reactor was 280 ° C., and the reaction temperature in the second reactor was 190 ° C.
[Comparative Example 6]
In Example 4, the reaction was performed in the same manner except that the reaction temperature in the first reactor was 150 ° C. and the reaction temperature in the second reactor was 190 ° C.

  The results are shown in Table 1.

FIG. 1 shows a simplified schematic of the reactor of the present invention.

Claims (11)

In the carbon monoxide methanation method in which the catalyst for carbon monoxide methanation and the hydrogen gas containing carbon monoxide gas are brought into contact, the reactor includes a first reactor and a second reactor connected to the first reactor. Become
The reaction temperature (T ₁ ) of the first reactor is in the range of 170 to 250 ° C., the reaction temperature (T ₂ ) of the second reactor is in the range of 100 to 170 ° C.,
A carbon monoxide methanation method, wherein a reaction temperature difference (T ₁ ) − (T ₂ ) with a reaction temperature (T ₂ ) of the second reactor is in a range of 20 to 150 ° C. The CO concentration (CF _CO ) in the carbon monoxide gas-containing hydrogen gas supplied to the first reactor is in the range of 0.3 to 1.0 Vol%, and the CO concentration in the outlet gas of the first reactor ( C1 _CO ) is 500
2. The carbon monoxide methanation method according to claim 1, wherein the CO concentration (C 2 _{CO 2} ) in the outlet gas of the second reactor is 10 ppm or less. Carbon monoxide methanation catalyst used in the first reactor is reaction temperature (T ₁ ) 190-210 ° C
The carbon monoxide methanation catalyst used in the second reactor is the catalyst having the highest CO removal rate at a reaction temperature (T ₂ ) of 120 to 140 ° C. The carbon monoxide methanation method according to claim 1 or 2. The carbon removal rate of the carbon monoxide methanation catalyst used in the first reactor is 95% or more, and the CO removal rate of the carbon monoxide methanation catalyst used in the second reactor is 98% or more. The method for methanation of carbon monoxide according to any one of claims 1 to 3. The carbon monoxide methanation catalyst used in the first reactor is selected from ZrO ₂ , CeO ₂ , NiO, CoO, Co ₃ O ₄ , Fe ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , and SiO _2. It comprises at least one kind of oxide or composite oxide, and further contains at least one kind of alkali metal oxide, alkaline earth metal oxide and rare earth metal oxide, and if necessary, 4B group, 6A group, 7A group and One or more metals selected from Group 8 are supported,
The carbon monoxide methanation catalyst used in the second reactor is one or more oxides selected from NiO, CoO, Co ₃ O ₄ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , TiO ₂ , and SiO ₂ , or 5. The carbon monoxide meta compound according to claim 1, wherein at least one metal selected from Group 4B, Group 6A, Group 7A, and Group 8 is supported on the composite oxide support. Nation method. The group 4B metal is Sn, the group 6A metal is Mo, W, the group 7A metal is Mn, Re, and the group 8 metal is Ru, Pt, Pd, Ni, Fe, and Co. The carbon monoxide methanation method according to any one of claims 1 to 5. The amount of metal supported in the catalyst for carbon monoxide methanation used in the second reactor is in the range of 0.5 to 15% by weight. Catalyst for carbon methanation. The carbon monoxide methanation method according to any one of claims 1 to 7, wherein Ru is contained as the metal, and a ratio of Ru in the supported metal is in a range of 20 to 90 wt%. 9. The carbon monoxide methanation method according to claim 1, wherein a CO adsorption tower filled with a CO adsorbent is connected to the second reactor. The CO adsorbent is made of zeolite on which one or more metals selected from Group 4B, Group 6A, Group 7A and Group 8 are supported, and the content of metal in the CO adsorbent is 0.5 to 15 wt. The method of carbon monoxide methanation according to any one of claims 1 to 9, wherein the methanation method is in the range of%. 11. The carbon monoxide methanation method according to claim 10, wherein the zeolite is at least one selected from ZSM-5 type zeolite, mordenite type zeolite, faujasite type zeolite, and β zeolite.

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