JP2002273225A - Method for manufacturing co removing catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a CO removing catalyst having the lessened halogen content and enhanced catalytic activity by depositing ruthenium component on a titania-alumina carrier. SOLUTION: This method for manufacturing the CO removing catalyst comprises a step to deposit ruthenium component on the titania-alumina carrier and a succeeding step for heat treating the ruthenium component-deposited carrier in the presence of steam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a CO removal catalyst for selectively oxidizing and removing CO in a hydrogen-containing gas. More specifically, the present invention relates to a method for efficiently producing a CO removal catalyst in which a ruthenium component is supported on a titania-alumina carrier, the content of halogen is small, and the catalytic activity is improved.

[0002]

2. Description of the Related Art In recent years, new energy technologies have been spotlighted due to environmental problems, and fuel cells have attracted attention as one of the new energy technologies. This fuel cell converts chemical energy into electric energy by electrochemically reacting hydrogen and oxygen, and has the feature of high energy use efficiency.
Practical research is being actively conducted for industrial or automotive use. As the fuel cell, types such as a phosphoric acid type, a molten carbonate type, a solid oxide type, and a solid polymer type are known according to the type of electrolyte used. on the other hand,
Hydrogen sources include liquefied natural gas mainly composed of methanol and methane; city gas mainly composed of natural gas; synthetic liquid fuel composed of natural gas as raw material; and petroleum-based carbon such as petroleum-based naphtha and kerosene. The use of hydrogen oil has been studied. When hydrogen is produced from these materials, generally,
A method of performing steam reforming or partial oxidation reforming treatment in the presence of a reforming catalyst is used. The hydrogen-containing gas obtained in these reactions usually contains CO together with the intended hydrogen gas.

[0003] Such a CO gas is liable to poison platinum (platinum catalyst) used as an electrode in a fuel cell, particularly in a low-temperature operation type fuel cell such as the above-mentioned polymer electrolyte fuel cell. If it is contained at a certain level or more, there is a serious problem that the power generation performance is reduced or power cannot be generated at all depending on the concentration. Accordingly, pure hydrogen is preferable as a fuel for a fuel cell using such a platinum-based electrocatalyst. However, as described above, a significant concentration of CO in addition to hydrogen is generally contained in the reformed gas.
Therefore, there is a strong demand for the development of a technology for converting this CO into CO ₂ or the like harmless to the platinum-based electrode catalyst and reducing the CO concentration in the fuel of the fuel cell. At that time, CO
It is said that it is desirable to reduce the concentration to a low concentration of usually 100 ppm or less, and even 10 ppm or less. Technology using a shift reaction (water gas shift reaction) represented by the following formula (1) as one of means for reducing the concentration of CO in a fuel gas (a hydrogen-containing gas in a reformed gas) of a fuel cell. 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 in reducing the CO concentration due to restrictions on chemical equilibrium. In general, the CO concentration is reduced to 1% or less. It is difficult.

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 a fuel gas to convert CO into CO ₂ . However, in this case, since a large amount of hydrogen is present in the fuel gas, when oxidizing CO, the hydrogen is also oxidized, and the CO concentration may not be sufficiently reduced. In order to solve this problem, when introducing oxygen or an oxygen-containing gas into the fuel gas to oxidize CO into CO ₂ , a method using a catalyst that selectively oxidizes only CO can be considered. JP-A-5-201702 discloses that
A method for producing a CO-free hydrogen-containing gas for selectively removing CO from a hydrogen-enriched CO-containing gas and supplying the CO to an automotive fuel cell system is disclosed. Here, a catalyst in which Rh or Ru is supported on an alumina carrier is used as a catalyst, but there is a problem that it can be applied only to a low CO concentration. Further, Japanese Patent Application Laid-Open No. 9-131531 discloses a catalyst for removing CO in a hydrogen-containing gas comprising ruthenium and an alkali metal compound and / or an alkaline earth metal compound supported on a titania carrier.

[0005]

However, in the case of the above-mentioned noble metal catalyst such as ruthenium, when preparing the catalyst,
Usually, a halide or a compound containing a halogen is often used as a raw material. While such a halogen-containing compound is easily soluble in water and easily supported,
Halogen remains in the catalyst even after the production of the catalyst, which has a disadvantage that it causes corrosion of metal members such as peripheral devices and piping systems. Further, when the above ruthenium-based catalyst in which halogen remains is used as a catalyst for removing CO from a hydrogen-containing gas, its catalytic activity is not practically sufficient, and a catalyst having a higher activity has been desired. As a method for removing the halogen in the catalyst, a reduction removal method using hydrogen or an oxidation removal method using an oxygen-containing gas is generally used. However, in the above-described reduction and removal method using hydrogen, an operation at a high temperature is required to completely remove halogen. As a result, in the case of a ruthenium-based catalyst, ruthenium sintering may be caused. Also, in the oxidation removal method using an oxidation-containing gas, there is a problem that ruthenium sintering easily occurs in the case of a ruthenium-based catalyst.

On the other hand, a method for removing halogen from a ruthenium-based catalyst by using an alkali agent has been disclosed (Japanese Patent Application Laid-Open No. HEI 10-1998).
-29803). In this method, as an alkali agent, an oxide of an alkali metal or an alkaline earth metal,
Hydroxide, carbonate, ammonia, organic bases such as amines, base-type ion exchange resins, etc., for example, after supporting ruthenium on a carrier, or reducing ruthenium on a carrier with hydrogen, etc. Thereafter, a dehalogenation treatment is performed. However, this method requires a post-process such as a washing process, and has a problem that the operation is complicated. Under such circumstances, the present invention selectively oxidizes and removes CO in a hydrogen-containing gas in which a ruthenium component is supported on a titania-alumina carrier, the content of halogen is small, and the catalytic activity is improved. It is an object of the present invention to provide a method for efficiently producing a CO removal catalyst by simple means.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, after supporting a ruthenium component on a carrier, heat-treating the ruthenium component in the presence of steam, It has been found that the purpose can be achieved. The present invention has been completed based on such findings. That is, the present invention provides a CO removal catalyst in which a ruthenium component is supported on a titania-alumina carrier.In this case, the ruthenium component is supported on a carrier and then heat-treated in the presence of water vapor. It is intended to provide a method for producing a catalyst.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The catalyst obtained by the production method of the present invention is a catalyst obtained by supporting a ruthenium component on a titania-alumina carrier and selectively oxidizing and removing CO in a hydrogen-containing gas. There is no particular limitation on the titania-alumina carrier in the above catalyst, and the titania
Any one of those commonly used as alumina carriers can be appropriately selected and used. As the shape of the carrier, any shape such as a spherical shape or a columnar shape, or a different shape such as a honeycomb can be used, but a granular shape is preferably used.

[0009] As a metal component supported on the carrier,
Requires a ruthenium component. Ruthenium source
Is, for example, RuCl_Three, RuCl_FourRuthenium chloride, etc.
, RuCl_Three・ NH_TwoO, Ru_Two(OH)_TwoCl_Four・
7NH_Three・ 3H_TwoO, K_Two(RuCl_Five(H_TwoO)),
(NH_Four)_Two(RuCl_Five(H_TwoO)), K_Two(RuC
l_Five(NO)), RuBr_Three・ NH_TwoO, Na_TwoRuO
_Four, Ru (NO) (NO _Three)_Three, (Ru_ThreeO (OAc)
₆(H_TwoO)_Three) OAc ・ nH_TwoO, K_Four(Ru (C
N)₆) · NH_TwoO, K_Two(Ru (NO_Two)_Four(OH)
(NO)), (Ru (NH)_Three)₆) Cl_Three, (Ru (N
H_Three)₆) Br_Three, (Ru (NH_Three)₆) Cl_Two, (R
u (NH_Three)₆) Br_Two, (Ru_ThreeO_Two(NH_Three)₁₄)
Cl₆・ H_TwoO, (Ru (NO) (NH_Three)_Five) C
l_Three, (Ru (OH) (NO) (NH_Three) _Four) (N
O_Three)_Two, RuCl_Two(PPh_Three)_Three, RuCl_Two(P
Ph_Three)_Four, (RuClH (PPh_Three)_Three) ・ C
₇H₈, RuH_Two(PPh_Three)_Four, RuClH (CO)
(PPh_Three)_Three, RuH_Two(CO) (PPh_Three)_Three,
(RuCl_Two(Cod)) n, Ru (CO)₁₂, Ru
(Acac)_Three, (Ru (HCOO) (CO)_Two) N,
Ru_TwoI_Four(P-cymene)_TwoRuthenium salts such as
These are dissolved in water, ethanol, etc.
Ruthenium component on a carrier using the prepared catalyst preparation solution
can do. Of the above ruthenium salts, preferred
Is RuCl in terms of handling._Three, RuCl_Three・ NH_TwoO
Ruthenium chloride is used.

The loading of the ruthenium component on the titania-alumina carrier can be carried out using the catalyst preparation liquid by a usual impregnation method, coprecipitation method, competitive adsorption method or the like. At this time, the treatment conditions may be appropriately selected according to various methods, and are usually at room temperature to 90 ° C. for 1 minute to 10 hours.
What is necessary is just to contact a support with a catalyst preparation liquid. The loading amount of the ruthenium component is not particularly limited, but usually, Ru is preferably 0.05 to 10% by weight relative to the titania-alumina carrier, and most preferably 0.3 to 3% by weight. If the ruthenium content is less than 0.05% by weight, C
The selective oxidation activity of O may be insufficient, while
If it exceeds 10% by weight, the amount of the ruthenium component used becomes excessively large, and the cost of the catalyst increases. In the present invention, it is preferable to use an alkali metal and / or alkaline earth metal component as a carrier component together with the ruthenium component in the CO removal catalyst. As the alkali metal component, potassium, sodium, lithium, cesium, or rubidium is preferably used. These can be used alone or in combination of two or more.

As the alkali metal source, K_TwoB_TenO₁₆,
KBr, KBrO_Three, KCN, K_TwoCO_Three, KCl, K
ClO_Three, KCLO_Four, KF, KHCO_Three, KHF_Two,
KH _TwoPO_Four, KH_Five(PO_Four)_Two, KHSO_Four, K
I, KIO_Three, KIO_Four, K_FourI_TwoO₉, KN_Three, KN
O_Two, KNO_Three, KOH, KPF₆, K_ThreePO_Four, KS
CN, K_TwoSO_Three, K_TwoSO_Four, K_TwoS_TwoO_Three, K_TwoS
_TwoO_Five, K_TwoS_TwoO₆, K_TwoS_TwoO₈, K (CH_ThreeCO
K) salts such as O); CsCl, CsClO_Three, CsCl
O_Four, CsHCO_Three, CsI, CsNO_Three, Cs_TwoSO
_Four, Cs (CH_ThreeCOO), Cs_TwoCO_Three, CsF etc.
Cs salt; Rb_TwoB_TenO₁₆, RbBr, RbBrO_Three, R
bCl, RbClO_Three, PbCLO_Four, RbI, RbN
O_Three, Rb_TwoSO_Four, Rb (CH_ThreeCOO)_Two, Rb_Two
CO_ThreeRb salt; Na_TwoB_FourO₇, NaB_TenO₁₆, N
aBr, NaBrO_Three, NaCN, Na_TwoCO_Three, Na
Cl, NaClO, NaClO_Three, NaClO_Four, Na
F, NaHCO_Three, NaHPO_Three, Na_TwoHPO_Three, N
a_TwoHPO_Four, NaH_TwoPO_Four, Na_ThreeHP_Two0₆, N
a _TwoH_TwoP_TwoO₇, NaI, NaIO_Three, NaIO_Four,
NaN_Three, NaNO_Two, NaNO_Three, NaOH, Na_Two
PO_Three, Na_ThreePO_Four, Na_FourP_TwoO₇, Na_TwoS, N
aSCN, Na_TwoSO_Three, Na_TwoSO_Four, Na_TwoS_TwoO
_Five, Na_TwoS_TwoO₆, Na (CH_ThreeNa such as COO)
Salt; LiBO_Two, Li_TwoB_FourO₇, LiBr, LiBr
O_Three, Li_TwoCO_Three, LiCl, LiClO_Three, LiC
10_Four, LiHCO_Three, Li_TwoHPO_Three, LiI, Li
N_Three, LiNH_FourSO_Four, LiNO_Two, LiNO_Three, L
iOH, LiSCN, Li_TwoSO_Four, Li_ThreeVO_FourEtc.
Li salts are used and these are dissolved in water, ethanol, etc.
The above alkali metal component using the catalyst preparation solution obtained by
Can be carried on a carrier.

The alkaline earth metal component includes
Lium, calcium, magnesium and strontium
Is preferably used. These can be used alone
Can be used in combination of two or more
You. BaBr is used as an alkaline earth metal source._Two, Ba
(BrO_Three)_Two, BaCl_Two, Ba (ClO_Two)_Two, B
a (CLO_Three)_Two, Ba (ClO_Four)_Two, BaI_Two, B
a (N_Three)_Two, Ba (NO_Two)_Two, Ba (NO_Three)_Two,
Ba (OH)_Two, BaS, BaS_TwoO₆, BaS
_FourO₆, Ba (SO_ThreeNH_Two)_TwoSuch as Ba salt; CaBr
_Two, CaI_Two, CaCl_Two, Ca (ClO_Three)_Two, Ca
(IO_Three)_Two, Ca (NO_Two)_Two, Ca (NO_Three)_Two,
CaSO_Four, CaS_TwoO_Three, CaS_TwoO₆, Ca (SO
_ThreeNH_Two)_Two, Ca (CH_ThreeCOO)_Two, Ca (H_TwoP
O_Four)_TwoCa salt, etc .; MgBr_Two, MgCO_Three, MgC
l_Two, Mg (ClO_Three)_Two, MgI_Two, Mg (IO_Three)
_Two, Mg (NO_Two)_Two, Mg (NO_Three)_Two, MgS
O_Three, MgSO_Four, MgS_TwoO₆, Mg (CH_ThreeCO
O)_Two, Mg (OH)_Two, Mg (ClO _Four)_TwoMg such as
Salt; SrBr_Two, SrCl_Two, SrI_Two, Sr (N
O_Three)_Two, SrO, SrS_TwoO_Three, SrS_TwoO₆, Sr
S_FourO₆, Sr (CH_ThreeCOO)_Two, Sr (OH)_Twoetc
Are used, and these are dissolved in water, ethanol, etc.
Alkaline earth metals using the catalyst preparation solution
The components can be supported on a carrier.

The alkali metal component and the alkaline earth metal component can be prepared by the usual impregnation method, coprecipitation method,
It can be supported on a carrier by a competitive adsorption method. At this time, the treatment conditions may be appropriately selected according to various methods, but usually, the treatment can be performed by bringing the carrier into contact with the catalyst preparation solution at a temperature of room temperature to 90 ° C. for 1 minute to 10 hours. The loading amounts of the alkali metal and the alkaline earth metal are not particularly limited, but each is usually preferably 0.01 to 10% by weight as a metal with respect to the titania-alumina carrier, and particularly preferably in the range of 0.03 to 3% by weight. Is optimal. If the content of these metals is less than 0.01% by weight, the selective oxidation activity of CO may not be sufficiently exhibited.
If the content exceeds 0% by weight, the selective oxidation activity of CO may be insufficient, and the amount of metal used may be unnecessarily excessive to increase the catalyst cost. The loading of ruthenium, alkali metal and alkaline earth metal may be carried out in any order, and if they can be carried out simultaneously, they may be carried out simultaneously.

After the above ruthenium, alkali metal and alkaline earth metal are supported on the titania-alumina carrier, drying is performed. Drying is preferably performed at a temperature of about 50 to 200 ° C. under reduced pressure or in an inert gas atmosphere. For example, natural drying, evaporation to dryness, drying using a rotary evaporator or a blow dryer can be performed.
The catalyst according to the present invention may be formed, for example, by extruding the catalyst itself or by a method of attaching the catalyst to a substrate such as a honeycomb or a ring. The method is not particularly limited.

In the method of the present invention, the support obtained by supporting the ruthenium component and, if necessary, the alkali metal and / or alkaline earth metal components on the titania-alumina support is converted into a halogen in the catalyst. Heat treatment is performed in the presence of water vapor in order to reduce the content. The heat treatment is preferably performed at a temperature of 200 to 800 ° C. for 15 minutes to 12 hours. If the heat treatment temperature is less than 200 ° C., the effect of reducing the halogen content in the catalyst may not be sufficiently exhibited, while if it exceeds 800 ° C., ruthenium tends to cause sintering. For these reasons, a more preferred heat treatment temperature is in the range of 300 to 600C. When the heat treatment time is less than 15 minutes at the temperature in the above range, the effect of reducing the halogen content in the catalyst may not be sufficiently exerted. On the other hand, when the heat treatment time exceeds 12 hours, the dehalogenation effect is improved for the treatment time. And the processing time is too long to be practical. For these reasons, a more preferred treatment time is between 30 minutes and 5 hours.

In the present invention, the heat treatment may be performed in the presence of steam alone, or in the presence of at least one gas selected from oxygen, nitrogen, hydrogen, carbon monoxide and carbon dioxide together with steam. May go. In this case, from the viewpoint of the dehalogenation effect, the water vapor concentration is 10% by volume.
As described above, the content is preferably 10 to 100% by volume. In the present invention, such a heat treatment in the presence of steam can reduce the halogen content in the catalyst to 0.2% by weight or less, and more preferably 0.1% by weight or less.
When the halogen content in the catalyst is more than 0.2% by weight,
The catalyst activity becomes insufficient, and it is difficult to sufficiently remove CO in the hydrogen-containing gas. In addition, it causes corrosion of metal members such as peripheral devices and piping systems. Next, a method for producing a hydrogen-containing gas with reduced carbon monoxide by oxidizing and removing carbon monoxide in a gas containing hydrogen as a main component using oxygen using a catalyst obtained by the production method of the present invention. Will be described.

The catalyst obtained as described above is generally reduced with hydrogen before use. This reduction treatment is usually performed at 250 to 600 ° C., preferably 380
The reaction is performed at a temperature of ５550 ° C. for 1 to 5 hours, preferably for 1 to 2 hours. With the catalyst obtained in this manner, oxygen is added to a hydrogen-containing gas containing hydrogen as a main component and containing at least CO to perform a selective oxidation reaction of CO with oxygen. The CO removal catalyst is suitable for selectively removing CO in a gas containing hydrogen as a main component (hereinafter, referred to as a reformed gas or the like) obtained by reforming or partially oxidizing a raw material for hydrogen production. It is used for the production of hydrogen-containing gas for fuel cells.

1. Reforming or Partial Oxidation Step of Hydrogen Production Raw Material The step for obtaining a reformed gas or the like containing hydrogen as a main component is performed in a conventional hydrogen production step, particularly in a hydrogen production step in a fuel cell system, as shown below. Any method such as a conventionally practiced or proposed method can be used. Therefore, in a fuel cell system provided with a reformer or the like in advance, a reformed gas or the like may be prepared by using the reformer as it is. Hydrogen production raw materials are hydrocarbons that can produce gas rich in hydrogen by steam reforming or partial oxidation, that is, hydrocarbons such as methane, ethane, propane, and butane, or natural gas (LNG), naphtha, gasoline, Hydrocarbon materials such as kerosene, light oil, heavy oil and asphalt; alcohols such as methanol, ethanol, propanol and butanol; oxygenated compounds such as methyl formate, methyl tertiary butyl ether and dimethyl ether; and various city gases and LPG , Synthesis gas, coal and the like. Among these, what kind of raw material for hydrogen production is used may be determined in consideration of various conditions such as the scale of the fuel cell system and the circumstances of supply of the raw material, but usually, methanol, methane, LNG, propane, etc. , LPG, naphtha, gasoline, kerosene, lower saturated hydrocarbons, city gas and the like are preferably used.

In general, when a sulfur content is present in these raw material hydrocarbons, it is preferable to perform desulfurization through the desulfurization step until the sulfur content is generally 1 ppm or less, preferably about 0.1 ppm or less. When the sulfur content in the raw material hydrocarbon is more than 1 ppm, it may cause the reforming catalyst to be deactivated. The desulfurization method is not particularly limited,
Hydrodesulfurization, adsorption desulfurization and the like can be used as appropriate. Technologies belonging to reforming or partial oxidation (hereinafter referred to as reforming reaction, etc.) include steam reforming, partial oxidation, combined steam reforming and partial oxidation, autothermal reforming, and other reforming. And the like. Usually, steam reforming (steam reforming) is the most common reforming reaction, but depending on the raw material, partial oxidation or other reforming reactions (for example, thermal reforming reaction such as thermal decomposition, contact reforming) Various catalytic reforming reactions such as decomposition and shift reactions)
Can also be applied as appropriate. At this time, different types of reforming reactions may be used in appropriate combination.

Hereinafter, steam reforming will be mainly described as a typical reforming reaction. In such a reforming reaction, catalysts and reaction conditions are generally selected so that the yield of hydrogen is as large as possible. However, it is difficult to completely suppress CO by-products. Even if it is used, there is a limit to the reduction of the CO concentration in the reformed gas. In fact, for the steam reforming reaction of hydrocarbons such as kerosene, the hydrogen yield and CO
The following formula (2) or formula (3) is used to suppress the by-product of: CH ₄ + 2H ₂ O → 4H ₂ + CO ₂ (2) Cn Hm + 2nH ₂ O → (2n + m / 2) H ₂ It is preferable to select various conditions so that the reaction represented by + nCO ₂ (3) occurs with as high selectivity as possible.

Further, CO may be modified and modified by utilizing the shift reaction represented by the above formula (1). However, since this shift reaction is an equilibrium reaction, a considerable concentration of CO remains. Therefore, the reformed gas or the like resulting from such a reaction usually contains a large amount of hydrogen, CO ₂ , unreacted water vapor, and a small amount of CO. A wide variety of catalysts are known as effective catalysts for the reforming reaction according to the type of raw materials, the type of reaction, the reaction conditions, and the like. Specific examples of some of them include catalysts effective for catalytic reforming reaction and partial oxidation of hydrocarbons, for example, supported Ru-based catalyst, supported Pt-based catalyst, supported Ni-based catalyst, and the like. it can. The conditions for the reforming reaction are:
Since it differs depending on conditions such as a reforming reaction, a catalyst, a type of a reaction apparatus, and a reaction method, it may be appropriately determined. In any case, it is desirable to select various conditions so that the conversion of the raw material is sufficiently increased (preferably to 100% or nearly 100%) and the yield of hydrogen is as large as possible. If necessary, a method of separating and recycling unreacted hydrocarbons and alcohols may be adopted.
Also, if necessary, the produced or unreacted CO ₂
And moisture or the like may be removed as appropriate.

2. Selective oxidation (conversion) removal process of CO A process in which oxygen is added to a raw material gas (reformed gas, etc.) containing hydrogen as a main component and a small amount of CO to selectively oxidize (convert) CO to CO _2. Therefore, it is necessary to suppress oxidation of hydrogen as much as possible. It is also necessary to suppress the conversion reaction of CO ₂ present in the raw material gas into CO (there is a possibility that a reverse shift reaction occurs because hydrogen is present in the raw material gas). Since the CO removal catalyst according to the present invention is usually used in a reduced state, it is preferable to perform a reduction treatment with hydrogen when the CO removal catalyst has not reached the reduced state. By using the catalyst according to the present invention, shows good results in CO selective oxidation removal for low feed gas of CO ₂ content, of course, good results in CO ₂ content is high condition can get. Usually, general C in a fuel cell system
The O ₂ concentration depends on the species of the raw material for hydrogen production on the upstream side, the reforming reaction conditions, the shift reaction conditions, and the like, and is usually about 5 to 40% by volume.

On the other hand, steam is usually present in the source gas obtained by steam reforming or the like, but the lower the steam concentration in the source gas, the better. Usually, it is contained in an amount of about 5 to 30%. Further, when the catalyst according to the present invention is used, the CO concentration in the raw material gas having a low CO concentration (0.6% by volume or less) can be effectively reduced, and the C concentration can be reduced.
The CO concentration in the source gas having a relatively high O concentration (0.6 to 2.0% by volume) can also be suitably reduced. By using the catalyst according to the present invention, CO ₂ can be contained in the raw material gas.
Even under the condition where the volume is 5% or more, the selective oxidation and removal of CO can be efficiently performed in a temperature range including a relatively high temperature of 60 to 300 ° C. In addition, the CO conversion removal reaction is an exothermic reaction, as is the simultaneous oxidation of hydrogen, which is a side reaction, and recovering the generated heat and utilizing it in the fuel cell is effective in improving the power generation efficiency. is there.

When oxygen gas is added to the reformed gas or the like, usually, pure oxygen (O ₂ ), air or oxygen-enriched air is suitably used. The added amount of the oxygen gas is preferably oxygen / CO (molar ratio) of 0.5 to 5, more preferably 1 to 5.
It is appropriate to adjust to be 4. If this ratio is small, the removal rate of CO is low, and if it is large, the consumption of hydrogen is too large, which is not preferable. The reaction pressure is not particularly limited, but in the case of a fuel cell, it is usually from normal pressure to 1 MPa.
G, preferably in a pressure range from normal pressure to 0.5 MPa · G. If the reaction pressure is set too high, the power for pressurization must be increased accordingly, which is economically disadvantageous. In particular, if it exceeds 1 MPa · G, it is subject to the regulations of the High Pressure Gas Control Law, As the explosion limit is widened, there is also the problem of reduced safety.

The reaction is usually carried out in a very wide temperature range of 60 ° C. or more, preferably 60 to 300 ° C.
The reaction can be suitably performed while stably maintaining the selectivity for the conversion reaction. If the reaction temperature is lower than 60 ° C., the reaction rate becomes slow, so that the CO removal rate (conversion rate) tends to be insufficient within a practical range of GHSV (gas volume space velocity). In addition, the above reaction is usually carried out at a GHSV of 5000
It is preferable to select a ^value within a range of 100000 hr ^-1 . Here, when the GHSV is reduced, a large amount of the catalyst is required. On the other hand, when the GHSV is excessively increased, the CO removal rate is reduced. For this reason, GHSV is preferably selected in the range of 6000 to 60,000 hr ^-1 . Since the CO conversion reaction in the CO conversion removal step is an exothermic reaction, the reaction raises the temperature of the catalyst layer.
If the temperature of the catalyst layer is too high, the selectivity of the catalyst for CO conversion removal usually deteriorates. For this reason, it is not preferable to react too much CO on a small amount of catalyst in a short time. In this sense, it is sometimes better not to make the GHSV too small.

There is no particular limitation on the reactor used for the conversion and removal of CO, and various types can be applied as long as the above reaction conditions can be satisfied. However, this conversion is an exothermic reaction. Therefore, in order to facilitate temperature control, it is desirable to use a reaction apparatus or a reactor having good removability of reaction heat. Specifically, for example, a heat exchange type reactor such as a multitube type or a plate fin type is suitably used. Depending on the case, a method of circulating the cooling medium in the catalyst layer or circulating the cooling medium outside the catalyst layer can be adopted.

Since the hydrogen-containing gas thus produced has a sufficiently reduced CO concentration as described above, the poisoning and deterioration of the platinum electrode catalyst of the fuel cell can be sufficiently reduced. Lifetime, power generation efficiency and power generation performance can be greatly improved. It is also possible to recover the heat generated by the CO conversion reaction. Further, the CO concentration in the hydrogen-containing gas containing a relatively high concentration of CO can be sufficiently reduced. The CO concentration in the hydrogen-containing gas for the fuel cell is 100 ppm by weight or less, preferably 50 ppm by weight.
It is desirable that it be less than or equal to 10 ppm by weight, more preferably less than or equal to 10 ppm by weight, but it is quite possible according to the process of the present invention to achieve this under a wide range of reaction conditions. The hydrogen-containing gas thus obtained can be suitably used as a fuel for various types of H ₂ -combustion fuel cells. In particular, a type using platinum (platinum catalyst) for at least the fuel electrode (negative electrode) is used. it can be advantageously utilized in various types of H ₂ combustion fuel cell as the supply fuel (phosphoric acid fuel cell, KOH-type fuel cell, such as low temperature operation type fuel cell including a polymer electrolyte fuel cell) to .

[0028]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, the chlorine content in the catalyst obtained in each example was measured by the following method. <Measurement of chlorine concentration> After thermal hydrolysis of the catalyst, chlorine atoms collected with water were analyzed by ion chromatography.

Comparative Example 1 Rutile type titania powder [trade name: CR-, manufactured by Ishihara Sangyo Co., Ltd.]
EL] 160 g and pseudo-boehmite alumina powder [manufactured by Catalyst Chemical Industry Co., Ltd., trade name: Cataloid-AP] 59.7
g was mixed well in a beaker and then charged into a kneader. After adding ion-exchanged water and kneading thoroughly,
Heating was performed, and the amount of water was adjusted so as to have a hardness suitable for extrusion molding. Next, this was extruded into a cylindrical shape having a diameter of about 2 mm by an extruder. Next, after heating and drying this molded body at 120 ° C. for 24 hours,
Calcination was performed at 4 ° C. for 4 hours. It contained 80% by weight of TiO ₂ and 20% by weight of Al ₂ O ₃ . Next, the molded body was adjusted to a length of 5 to 10 mm to form a titania-alumina carrier, on which ruthenium and potassium were supported by the following method. Ruthenium chloride (38.
0.263 g and potassium nitrate 0.0
26 g was dissolved in 2.0 ml of water to prepare an impregnating liquid. Next, 10 g of the above impregnated titania-alumina carrier was impregnated with the impregnated liquid, heated at 60 ° C., dried, and calcined in air at 500 ° C. for 4 hours to obtain a catalyst A. The chlorine content in this catalyst A was 0.1.
38% by weight.

Example 1 In the same manner as in Comparative Example 1, 10 g of a titania-alumina carrier was used.
Is impregnated with an impregnating solution containing ruthenium chloride and potassium nitrate, and the dried product is put into a rotary kiln and
At 0 ° C., water was supplied at 0.7 ml / min (in terms of liquid), and rotary steam treatment was performed for 1 hour in a 100% steam atmosphere to obtain a catalyst B. The chlorine content in this catalyst B was 0.1.
08% by weight. Example 2 In Example 1, instead of treating in a 100% steam atmosphere, air containing 60% by volume of steam was supplied at a rate of 1.4 liter / minute, and a rotary steam treatment was performed at 500 ° C. for 1 hour to obtain a catalyst C. I got The chlorine content in this catalyst C was 0.1
It was 5% by weight.

Example 3 1 g of the catalyst A obtained in Comparative Example 1 was charged into a reactor, and
Water was supplied at 0.03 ml / min (in terms of liquid) while flowing hydrogen gas at 148 ml / min at 0 ° C., and steam treatment was performed for 15 minutes to obtain Catalyst D. The chlorine content in this catalyst D was 0.12% by weight. In addition,
This catalyst was not subjected to a hydrogen reduction treatment in the performance evaluation described below.

Example 4 A catalyst E was obtained in the same manner as in Example 3 except that the steam treatment time was changed to 30 minutes. The chlorine content in this catalyst E was 0.08% by weight. In addition, this catalyst was not subjected to the hydrogen reduction treatment in the performance evaluation as in Example 3. Example 5 A catalyst F was obtained in the same manner as in Example 3, except that the steam treatment time was changed to 1 hour. This catalyst F
The chlorine content therein was less than 0.05% by weight. In addition,
This catalyst was not subjected to the hydrogen reduction treatment in the performance evaluation as in Example 3.

Example 6 An aqueous solution obtained by dissolving 115.1 g of ruthenium chloride (containing 38% by weight as Ru metal) in 340 g of distilled water and an aqueous solution obtained by dissolving 19.4 g of potassium nitrate in 150 g of distilled water were mixed. The mixture was stirred for 20 minutes to prepare a uniform impregnation liquid. Next, a titania-alumina carrier [pore volume 0.
2 ml / g, 3 mmφ bead, manufactured by Sekiyu Kasei Kogyo Co., Ltd.] 360 g is placed in a 10 liter container with vacuum degassing, and subjected to vacuum degassing treatment for 20 minutes.
90 g was gradually charged. Further, the impregnating liquid adhering to the container was washed off with 122 g of water, and the impregnating liquid was poured into the above-mentioned container with vacuum degassing so that the impregnating liquid was uniformly distributed on the carrier. Then, after leaving to stand at room temperature for 30 minutes,
The temperature was raised to 120 ° C. at a rate of ° C./min, and the temperature was maintained at 120 ° C. for 1 hour, followed by spin drying to obtain Sample X. This sample X was calcined at 500 ° C. for 4 hours to obtain a sample Y. Next, 200 g of the sample X was put into a rotary kiln,
After the temperature was raised to 500 ° C. at a rate of ° C./min, a rotary steam treatment was performed at 500 ° C. for 1 hour. Water from 300 ℃ to 5
Introduced at a rate of 2.3 g / min during baking for 1 hour at 00 ° C. Thus, catalyst G was obtained. The chlorine content in this catalyst G was 0.17% by weight.

Example 7 200 g of the sample Y in Example 6 was put into a rotary kiln, and the temperature was raised to 500 ° C. at a rate of 4 ° C./min. went. Water is heated from 300 ° C to 500 ° C for 1 hour,
It was introduced at a rate of 2.3 g / min. Thus, the catalyst H
I got The chlorine content in this catalyst H was 0.15% by weight. Example 8 200 g of the sample X in Example 6 was put into a rotary kiln, and the temperature was raised to 500 ° C. at a rate of 4 ° C./min while blowing air at a rate of 2 L / min.
Rotary steam treatment was performed at 00 ° C. for 1 hour. Water is 300
Introduced at a rate of 2.3 g / min during 1 hour baking from 500C to 500C. Thus, catalyst I was obtained. The chlorine content in this catalyst I was 0.18% by weight.

Example 9 200 g of the sample Y in Example 6 was put into a rotary kiln, and air was blown into the rotary kiln at a rate of 4 ° C./min to 500 ° C. while blowing air at a rate of 2 L / min. After warming, rotary steam treatment was performed at 500 ° C. for 1 hour. Water is heated from 300 ° C to 500 ° C for 1 hour,
It was introduced at a rate of 2.3 g / min. Thus, the catalyst J
I got The chlorine content in this catalyst J was 0.15% by weight. Example 10 200 g of the sample X in Example 6 was charged into a rotary kiln, heated to 500 ° C. at a rate of 4 ° C./min, and then subjected to rotary steam treatment at 500 ° C. for 1 hour, as in Example 6. Water is heated from 300 ° C to 500 ° C for 1 hour,
It was introduced at a rate of 20 g / min. Thus, catalyst K was obtained. The chlorine content in this catalyst K was 0.07% by weight.

Example 11 200 g of the sample X in Example 6 was put into a rotary kiln, and the temperature was raised to 500 ° C. at a rate of 4 ° C./min while blowing nitrogen at a rate of 2 L / min.
Rotary steam treatment was performed at 00 ° C. for 1 hour. Water is 300
Introduced at a rate of 2.3 g / min during 1 hour baking from 500C to 500C. Thus, catalyst L was obtained. The chlorine content in this catalyst L was 0.15% by weight. Comparative Example 2 200 g of the sample X in Example 6 was put into a rotary kiln, and the temperature was raised to 500 ° C. at a rate of 4 ° C./min.
Rotary firing treatment was performed at 00 ° C. for 1 hour to obtain a catalyst M.
The chlorine content in this catalyst M was 0.34% by weight.

<Evaluation of Catalyst> Each of the catalysts prepared in Examples 1 to 11 and Comparative Examples 1 and 2 was sized to 16 to 32 mesh, and 1 g was filled in a reaction tube having an inner diameter of 6 mm, and hydrogen gas was introduced. While heating up to 500 ° C in 1 hour,
The mixture was kept at 500 ° C. for 1 hour and subjected to a hydrogen reduction treatment. Next, hydrogen containing CO / O ₂ / CO ₂ / H ₂ O / N ₂ / H ₂ in a volume ratio of 0.6 / 1.5 / 15/20 / 6.0 / balance is added to the reaction tube. The contained gas was supplied at an inlet temperature of 150 ° C and GH
Introduced under the condition of SV40,000h ^-1 , selective oxidation treatment of CO was performed. The hydrogen-containing gas at the outlet of the reactor was sampled, and the CO concentration was measured by gas chromatography. The results are shown in Table 1.

[0038]

[Table 1]

[0039]

According to the present invention, the ruthenium component is supported on the titania-alumina carrier, the content of halogen is small, and the catalytic activity is improved. A CO removal catalyst can be efficiently produced by simple means. By using the catalyst obtained by the method of the present invention, it is possible to sufficiently reduce the CO concentration in the hydrogen-containing gas used as a fuel for the fuel cell, and to corrode metal members such as peripheral devices and piping systems. There are few things.

Continued on the front page F-term (reference) 4G040 EA02 EA03 EA06 EB31 4G069 AA03 AA08 BA01A BA01B BA04A BA04B BA20A BA20B BB02A BB02B BC01A BC02A BC03A BC04A BC05A BC06A BC08A BC09A BC10A BC12 BC30 EBA BC13 BCBC EA03 EA06 EB31 5H027 AA06 BA01 BA16

Claims (5)

[Claims] 1. A method for producing a CO removal catalyst comprising a ruthenium component supported on a titania-alumina carrier, wherein the ruthenium component is supported on a carrier and then heat-treated in the presence of steam. Manufacturing method. 2. The method for producing a CO removal catalyst according to claim 1, wherein the CO removal catalyst further supports an alkali metal and / or alkaline earth metal component. 3. A heat treatment in the presence of steam is performed for 200 hours.
2. The method according to claim 1, wherein the heat treatment is performed at a temperature of from about 800 DEG C. to about 15 minutes to 12 hours.
Or a method for producing a CO removal catalyst according to item 2. 4. The heat treatment according to claim 1, wherein the heat treatment in the presence of steam is performed in the presence of at least one gas selected from oxygen, nitrogen, hydrogen, carbon monoxide and carbon dioxide together with steam. A method for producing the CO removal catalyst according to the above. 5. The method for producing a CO removal catalyst according to claim 1, wherein the heat treatment in the presence of steam is performed in an atmosphere having a steam concentration of 10 to 100% by volume.