JP2002273222A - Catalyst for removing co - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CO-removing catalyst whose halogen content can be decreased without deteriorating the catalytic performance, by which subsequently CO in hydrogen-containing gas can efficiently be removed selectively by oxidation and which does not corrode a manufacturing apparatus such as surrounding equipment and pipeline systems, and to provide a method for manufacturing the hydrogen-containing gas, particularly the hydrogen-containing gas applied suitably in a fuel cell, by removing CO in the hydrogen-containing gas by using the CO removing catalyst. SOLUTION: This CO removing catalyst is obtained by depositing at least ruthenium component on a titania-alumina carrier and has <=0.2 wt.% halogen content and >=10 μmol/g CO amount to be adsorbed on it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for selectively oxidizing and removing CO from a hydrogen-containing gas.
The present invention relates to a CO removal catalyst for improving the selective oxidation activity of O, and a method for producing a hydrogen-containing gas using the catalyst.

[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. In addition, the present inventors have found that 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 with higher activity is desired. Was rare.

The present invention has been made under such circumstances, and the content of halogen in the catalyst is reduced without deterioration of the catalyst. As a result, the dispersibility of the metal component is improved, and the hydrogen-containing gas is improved. Removal catalyst capable of efficiently and selectively oxidizing and removing CO in the gas and preventing corrosion of production equipment such as peripheral equipment and piping systems, and a hydrogen-containing gas using the same, particularly a fuel cell It is an object of the present invention to provide a CO removal catalyst for removing CO in a hydrogen-containing gas, which can be suitably applied for use.

[0007]

Means for Solving the Problems The present inventors have intensively studied to solve the above-mentioned problems. As a result, in a ruthenium-based catalyst, by reducing the halogen mixed during the preparation of the catalyst to a certain concentration or less, and using a catalyst having a CO adsorption amount of a specific amount or more as a catalyst for removing CO in a hydrogen-containing gas, It has been found that the object of the present invention can be effectively achieved. The present invention has been completed based on such findings. That is, the present invention relates to a CO removal catalyst comprising at least a ruthenium component supported on a titania-alumina carrier, wherein the halogen content is 0.2% by weight or less and the CO adsorption amount is 10 μmol / g or more. An object of the present invention is to provide a CO removal catalyst for removing CO in a hydrogen-containing gas.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The CO removal catalyst of the present invention has a halogen content of
It is characterized in that it is not more than 0.2% by weight and the amount of adsorbed CO is not less than 10 μmol / g. Halogen content 0.2% by weight
When it exceeds, the removal of CO in the hydrogen-containing gas becomes insufficient. From this viewpoint, the halogen content in the catalyst is more preferably 0.1% by weight or less. Examples of the halogen include chlorine. In addition, the CO adsorption amount is 10
If it is less than μmol / g, the degree of dispersion of ruthenium is not sufficient, so that the removal of CO becomes insufficient. The halogen content in the catalyst can be achieved by heat-treating and / or washing the catalyst after supporting and drying the metal component. That is,
The CO removal catalyst of the present invention is a titania-alumina carrier,
It is obtained by impregnating with an impregnating liquid containing a metal component containing at least a ruthenium component, drying the impregnating liquid, and then performing water washing with a water washing liquid or heat treatment. Examples of the rinsing liquid that can be used for rinsing include water, an alkaline aqueous solution having a pH of 8 or more, a combination thereof, and the like. Further, water may coexist at the time of the heat treatment.

In the present invention, the washing of the CO removal catalyst with water is preferably performed at a temperature of 30 ° C. or higher, more preferably at a temperature of 50 ° C. or higher. If the washing temperature is lower than the above temperature,
A long time is required for removing halogen, which is not preferable in some cases. Such washing with water can be performed after the catalyst is impregnated with the impregnation liquid in the catalyst preparation step and dried.
After the drying, it may be performed after a heat treatment described below is performed. The halogen content in the catalyst of the present invention can be reduced by performing a heat treatment after the impregnation and drying of the metal component. As such a heat treatment, 250 to 6
A method of heating the catalyst at a temperature of 00 ° C. is preferred. When the heat treatment temperature is lower than 250 ° C., the halogen reduction effect and the CO removal efficiency are not sufficient, and when the heat treatment temperature is higher than 600 ° C., ruthenium metal may be undesirably aggregated. In this respect, the heat treatment temperature is more preferably 380 to 550 ° C.

Examples of the heat treatment method include baking in air, heat treatment in an atmosphere of an inert gas such as nitrogen, heat treatment in an atmosphere containing a reactive gas such as hydrogen, carbon monoxide, and steam. In the present invention, a method performed in a steam atmosphere is preferred. The time of the heat treatment can be appropriately adjusted according to the treatment temperature, but in the present invention,
From the viewpoint of sufficiently reducing the halogen content, for example, it is preferably performed for 15 minutes to 20 hours, and more preferably for 30 minutes to 10 hours. This heat treatment is performed in the catalyst preparation step.
It can be carried out after impregnating the carrier with the impregnating liquid and drying. The heat treatment may be performed once within the above-mentioned time range, or may be performed a plurality of times, such as once after cooling once. Further, in the present invention, it is also preferable to perform the above-mentioned water washing treatment after the heat treatment, or to carry out this heat treatment after the water washing treatment in order to enhance the effect of the present invention.

As the carrier used in the CO removal catalyst of the present invention, a carrier composed of titania-alumina is used. As a method for producing the titania-alumina carrier, any method may be used as long as a carrier comprising both of them can be formed. For example, a method of mixing titania and alumina, a method of attaching titania to an alumina molded body (including alumina particles and powder), The method is preferably used. As a method for mixing titania and alumina, there is a method in which titania powder and alumina powder or pseudo-boehmite alumina are mixed with water, followed by molding, drying, and firing. Extrusion may be usually used for molding, and at that time, an organic binder can be added to improve moldability. Suitable carriers can also be obtained by mixing titania with an alumina binder. Further, titanium alkoxide and aluminum alkoxide were dissolved in a solvent such as alcohol by adding water to a mixed solution, hydrolyzed, and the coprecipitated precipitate was formed, dried and calcined in the same manner as described above. Is also good. In this case, the obtained titania / alumina mass ratio is 10/90.
It is preferably 90 to 90/10.

On the other hand, the method of adhering titania to the alumina compact may be as follows. In an organic solvent, a titania powder (the titania powder may be a titania powder supporting a metal to be described later), and if necessary, an organic binder and pseudo-boehmite alumina powder are added and dispersed well. The alumina molded body is immersed in the mixed liquid (usually in a slurry form), and the mixed liquid is sufficiently immersed. After the titania powder is adhered to the alumina molded body, the alumina molded body is taken out. The alumina compact may be dried and fired. Alternatively, titanium alkoxide or titanium tetrachloride and an alumina compact are added to alcohol, water is added to this solution to hydrolyze the titanium alkoxide or titanium tetrachloride, and titanium hydroxide is formed on the alumina compact. The precipitate may be dried and fired. As can be seen from these attaching methods, titania may be adhered in a manner of supporting titania on the alumina molded body. In the case of a method in which titania is adhered to an alumina molded body, the obtained titania / alumina mass ratio is 0.1 / 99.9 to 5
0/50, preferably 0.5 / 99.5 to 50/50,
More preferably, the ratio is 1/99 to 50/50. Including both of the above methods, the mass ratio of titania / alumina is 0.1 / 99.9 to 90/10, preferably 0.5 / 99.5 to 90/10, more preferably 1 /.
Desirably, it is 99 to 90/10. If this ratio deviates from the above range, the CO removal performance becomes insufficient, which may be undesirable.

The raw material of alumina used in the above method for producing a carrier may contain aluminum atoms. Examples of commonly used materials include aluminum nitrate, aluminum hydroxide, aluminum alkoxide, pseudoboehmite alumina, α-alumina, γ-alumina and the like. Pseudo-boehmite alumina, α-alumina, γ-alumina and the like can be made from aluminum nitrate, aluminum hydroxide, aluminum alkoxide and the like. What is necessary is just to select these raw materials which are easy to use according to the manufacturing method of a support | carrier etc. As the titania raw material of the carrier, any material containing a titanium atom may be used, and usually, titanium alkoxide, titanium tetrachloride, amorphous titania powder, anatase-type titania powder, rutile-type titania powder and the like can be mentioned. Amorphous titania powder, anatase-type titania powder, rutile-type titania powder and the like can be made of titanium alkoxide, titanium tetrachloride or the like. What is necessary is just to select these raw materials which are easy to use according to the manufacturing method of a support | carrier etc.

The carrier may consist of titania and alumina, but may also contain other refractory inorganic oxides. For example, it may contain zirconia, silica, or the like. As the zirconia source, any material containing a zirconium atom may be used, but zirconium hydroxide, zirconium oxychloride, zirconium oxynitrate, zirconium nitrate, zirconium tetrachloride, zirconia powder and the like can be used. The zirconia powder can be made from zirconium hydroxide, zirconium oxychloride, zirconium oxynitrate, zirconium nitrate, zirconium tetrachloride. As the silica raw material, any material containing a silicon atom may be used, but silicon tetrachloride, sodium silicate, ethyl silicate, silica gel, silica sol and the like can be used. Silica gel can be made from silicon tetrachloride, sodium silicate, ethyl silicate, silica sol, and the like.

In the CO removal catalyst of the present invention, titania
-The metal component supported on the alumina support
A nickel component is essential. As a ruthenium source,
For example, RuCl_Three, RuCl_FourRuthenium chloride, Ru
Cl_Three・ NH_TwoO, Ru_Two(OH)_TwoCl_Four・ 7NH_Three
・ 3H_TwoO, K_Two(RuCl_Five(H_TwoO)), (N
H _Four)_Two(RuCl_Five(H_TwoO)), K_Two(RuCl_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 by using the catalyst preparation solution 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 content of ruthenium is less than the lower limit of the above range,
The conversion activity of CO becomes insufficient. On the other hand, if the loading ratio is too high, the amount of the ruthenium component used becomes excessively large and the catalyst cost increases.

In the present invention, the above-mentioned ruthenium component and
Both are alkali metals and / or alkalis as supporting components
Preferably, an earth metal component is used. Alkali metal component
Minutes include potassium, sodium, lithium, cesium
Or rubidium is preferably used. These alone
Can be used in combination, but used in combination of two or more
You can also. As the alkali metal source, K_TwoB_Ten
O₁₆, KBr, KBrO_Three, KCN, K_TwoCO_Three, KC
1, KCLO_Three, KCLO_Four, KF, KHCO_Three, KH
F_Two, KH _TwoPO_Four, KH_Five(PO_Four)_Two, KHS
O_Four, KI, KIO_Three, KIO_Four, K_FourI_TwoO₉, KN
_Three, KNO_Two, KNO_Three, KOH, KPF₆, K_ThreePO
_Four, KSCN, K_TwoSO_Three, K_TwoSO_Four, K_TwoS
_TwoO_Three, K_TwoS_TwoO_Five, K_TwoS_TwoO₆, K_TwoS_TwoO₈,
K (CH_ThreeCO salts such as COO); CsCl, CsCl
O_Three, CsCLO_Four, CsHCO_Three, CsI, CsNO
_Three, Cs_TwoSO_Four, Cs (CH_ThreeCOO), Cs_TwoCO
_Three, CsF and the like; Rb_TwoB_TenO₁₆, RbBr, R
bBrO_Three, RbCl, RbClO_Three, PbCLO_Four,
RbI, RbNO_Three, Rb_TwoSO_Four, Rb (CH_ThreeCO
O)_Two, Rb_TwoCO_ThreeRb salt; Na_TwoB_FourO₇, N
aB_TenO₁₆, NaBr, NaBrO_Three, NaCN, Na
_TwoCO_Three, NaCl, NaClO, NaClO_Three, Na
ClO_Four, NaF, NaHCO_Three, NaHPO_Three, Na
_TwoHPO_Three, Na_TwoHPO_Four, NaH_TwoPO_Four, Na_Three
HP_Two0₆, Na _TwoH_TwoP_TwoO₇, NaI, NaI
O_Three, NaIO_Four, NaN_Three, NaNO_Two, NaN
O_Three, NaOH, Na_TwoPO_Three, Na_ThreePO_Four, Na_Four
P_TwoO₇, Na_TwoS, NaSCN, Na_TwoSO_Three, Na
_TwoSO_Four, Na_TwoS_TwoO_Five, Na_TwoS_TwoO₆, Na (C
H_ThreeNa salt such as COO); LiBO_Two, Li_TwoB
_FourO₇, LiBr, LiBrO_Three, Li_TwoCO_Three, Li
Cl, LiClO_Three, LiClO_Four, LiHCO_Three, L
i_TwoHPO_Three, LiI, LiN_Three, LiNH_FourSO_Four,
LiNO_Two, LiNO_Three, LiOH, LiSCN, Li
_TwoSO_Four, Li_ThreeVO_FourLi salts such as
Is dissolved in water, ethanol, etc.
Can be used to support the alkali metal component on a carrier.
Wear.

As the alkaline earth metal component,
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 using the above-mentioned catalyst preparation solution 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 the lower limit of the above range, the selective oxidation activity of CO may not be sufficiently exhibited.On the other hand, when the loading ratio is too high, the selective oxidation activity of CO is insufficient. In some cases, the amount of metal used becomes unnecessarily excessive and the cost of the catalyst increases. 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 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 with a rotary evaporator or a blow dryer can be performed. The catalyst of the present invention may be formed by, for example, extruding the catalyst itself or by a method of attaching the catalyst to a honeycomb or ring-shaped substrate, and the method is not particularly limited. 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 with oxygen using the catalyst 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 of the present invention selectively removes CO in a hydrogen-based gas (hereinafter, referred to as a reformed gas or the like) obtained by reforming or partially oxidizing a hydrogen production raw material. It is preferably used for producing 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.

When a sulfur content is present in these raw material hydrocarbons, the sulfur content is usually reduced to 1 through the desulfurization step.
It is preferable to perform desulfurization until the amount becomes less than or equal to ppm, 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. Although the desulfurization method is not particularly limited, hydrodesulfurization, adsorption desulfurization and the like can be used as appropriate. Technology belonging to reforming or partial oxidation (hereinafter referred to as reforming reaction, etc.)
Examples include steam reforming, partial oxidation, a combination of steam reforming and partial oxidation, autothermal reforming, and other reforming reactions. 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 reaction) can also be appropriately applied. 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, regarding the steam reforming reaction of hydrocarbons such as kerosene,
In order to suppress the yield of hydrogen and the by-product of CO, the following equation (2) or equation (3): CH ₄ + 2H ₂ O → 4H ₂ + CO ₂ (2) Cn Hm + 2nH ₂ O → ( It is preferable to select various conditions so that the reaction represented by (2n + m / 2) H ₂ + 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 step of CO The method for producing a hydrogen-containing gas of the present invention selectively removes CO by adding oxygen to a raw material gas (reformed gas or the like) containing hydrogen as a main component and a small amount of CO. It is to be oxidized (converted) to CO _2, and it is necessary to suppress the 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). C of the present invention
Since the O-removing catalyst is usually used in a reduced state, it is preferable to perform a reduction treatment with hydrogen when the O-removed catalyst has not reached the reduced state. By using the catalyst of the present invention, CO ₂ shows good results in selective oxidation removal of CO for a low content of the raw material gas of course, CO ₂ performed better in high content conditions to give Can be Generally, the general CO ₂ concentration in a fuel cell system depends on the type 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%. When the catalyst of the present invention is used, the CO concentration is low (0.6% by volume).
Hereinafter, the CO concentration in the source gas can also be effectively reduced, and the CO concentration in the source gas having a relatively high CO concentration (0.6 to 2.0% by volume) can be suitably reduced. Efficient selective conversion and removal of CO in a temperature range including a relatively high temperature of 60 to 300 ° C. even under conditions where CO ₂ is present in the raw material gas by 15% or more by using the catalyst of the present invention. Can be. 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 of reactors can be applied as long as the above reaction conditions can be satisfied. However, this conversion reaction 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, and its life and power generation can be reduced. 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. Although the CO concentration in the hydrogen-containing gas for a fuel cell is desirably 100 ppm by weight or less, preferably 50 ppm by weight or less, and more preferably 10 ppm by weight or less, according to the method of the present invention, under a wide range of reaction conditions, It is quite possible to achieve this.

The hydrogen-containing gas thus obtained is
It can be suitably used as a fuel for various types of H ₂ -combustion fuel cells. In particular, various types of H ₂ -combustion fuel cells (phosphoric acid) of a type using platinum (platinum catalyst) for at least a fuel electrode (anode) Fuel cell, a KOH fuel cell, a polymer electrolyte fuel cell, and other low-temperature operation fuel cells).
The method of the present invention was applied between the fuel cell and the reformer of the conventional fuel cell system (if a reformer is provided after the reformer, the reformer is also considered as a part of the reformer). By incorporating an oxygen introduction device and a reaction device, or by adjusting the reaction conditions as described above using the catalyst as a CO conversion removal catalyst in those already equipped with an oxygen introduction device and a conversion reaction device, It is possible to configure a fuel cell system that is superior to conventional fuel cell systems.

[0030]

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 of the catalyst obtained in each example, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas after the selective oxidation reaction (reactor outlet) were measured by the following methods. <Measurement of chlorine concentration> After thermal hydrolysis of the catalyst, chlorine atoms collected with water were analyzed by ion chromatography.

<Measurement of Amount of CO Adsorption> After about 0.5 g of the catalyst was filled in the adsorption cell, hydrogen reduction was performed at 500 ° C. as a pretreatment. Next, CO gas is pulsed into the catalyst. Of the introduced CO, the non-adsorbed CO flows out of the catalyst and is detected. Therefore, the amount obtained by subtracting the detected CO amount from the introduced CO amount is the amount of CO adsorbed by one CO introduction. CO is introduced several times until the CO outflow reaches a steady value, and the amount of CO adsorbed on the catalyst is determined from the following equation. The amount of CO adsorbed on the catalyst = (the amount of one CO introduction × the number of times of introduction) − (the sum of the detected gas amounts) <Measurement of CO concentration> The obtained catalyst was sized to 16 to 32 mesh and 1 g Was filled in a reaction tube having an inner diameter of 6 mm.
A hydrogen-containing gas was introduced into the reaction tube at an inlet temperature of 150 ° C. under the conditions of GHSV: 40000 h ⁻¹ , and a CO selective oxidation treatment was performed. The obtained 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. Hydrogen-containing gas: CO / O ₂ / CO ₂ / H ₂ O / N ₂ / H ₂ = 0.6 / 1.5 / (volume%) 15/20 / 6.0 / Balance

Comparative Example 1 Rutile type titania powder (Ishihara Sangyo CR-EL) 160 g
And pseudo boehmite alumina powder (Catalyst Chemical, Catalo
id-AP) 59.7 g was mixed well in a beaker,
I put it in a kneader. Ion-exchanged water was added thereto, and the mixture was sufficiently kneaded and heated to adjust the water content to a hardness suitable for extrusion, and then extruded into a column having a diameter of about 2 mm using an extruder. This molded body is placed in a dryer at 120 ° C. for 2 hours.
It was dried for 4 hours to remove moisture, and then calcined at 500 ° C. for 4 hours. The Baked shaped body contained 80 wt% of TiO ₂ and 20 wt% Al ₂ O _3. On the other hand, ruthenium chloride (containing 38.03% by weight as Ru metal) 0.263
g and 0.026 g of potassium nitrate were dissolved in 2.0 cc of water to obtain an impregnation liquid. This impregnating liquid was used to obtain the molded product obtained above with 0.5.
The catalyst A was obtained by impregnating 10 g of a length of about 1 cm, drying at a temperature of 60 ° C., and calcining at 500 ° C. for 4 hours in the air. After reducing the catalyst A1g at 500 ° C. for 1 hour, the reaction was evaluated. Chlorine content of catalyst A, CO adsorption amount and CO in hydrogen-containing gas at reactor outlet
The concentrations are shown in Table 1.

Example 1 The catalyst A obtained in Comparative Example 1 was washed with distilled water at 50 ° C. After washing until no chlorine ions are detected in the washing solution, the washed catalyst is dried at 60 ° C.
It was calcined at a temperature of 00 ° C. for 4 hours to obtain a catalyst B. After 1 g of the catalyst B was reduced at 500 ° C. for 1 hour, the reaction was evaluated. Table 1 shows the chlorine content of catalyst B, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the outlet of the reactor. Example 2 A catalyst C was obtained in the same manner as in Comparative Example 1 except that, instead of being dried and then calcined at a temperature of 500 ° C. for 4 hours, it was calcined at a temperature of 500 ° C. for 8 hours. This catalyst C
After reducing 1 g at 500 ° C. for 1 hour, the reaction was evaluated. Table 1 shows the chlorine content, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the outlet of the reactor of the catalyst C.

Example 3 The catalyst A obtained in Comparative Example 1 was further calcined at a temperature of 500 ° C. for 4 hours to obtain a catalyst D. 1 g of this catalyst D
After reduction treatment at 00 ° C. for 1 hour, the reaction was evaluated. Table 1 shows the chlorine content, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the outlet of the reactor of the catalyst D. Example 4 The catalyst A obtained in Comparative Example 1 was further washed at 80 ° C. using an aqueous solution of ammonium hydroxide having a pH of 9. After washing until no chlorine ions were detected in the washing solution, the solution was dried at 60 ° C., and calcined in air at 500 ° C. for 4 hours to obtain a catalyst E. After 1 g of this catalyst E was reduced at 500 ° C. for 1 hour, the reaction was evaluated. Chlorine content of catalyst E, C
Table 1 shows the O adsorption amount and the CO concentration in the hydrogen-containing gas at the outlet of the reactor.

Example 5 After impregnation and drying were carried out in the same manner as in Comparative Example 1,
The mixture was stirred and washed at 50 ° C. for 1 hour using an aqueous ammonia solution of 12.7. Then, after washing with distilled water until no chlorine ions are detected in the washing solution, dried at 120 ℃,
Catalyst F was obtained. After reducing 1 g of the catalyst F at 500 ° C. for 1 hour, the reaction was evaluated. The chlorine content of catalyst F,
Table 1 shows the CO adsorption amount and the CO concentration in the hydrogen-containing gas at the outlet of the reactor. Example 6 A catalyst G was obtained in the same manner as in Example 5 except that a 20% aqueous NaOH solution was used instead of the treatment with an aqueous ammonia solution having a pH of 12.7. After reducing 1 g of this catalyst G at 500 ° C. for 1 hour, the reaction was evaluated. Table 1 shows the chlorine content, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the outlet of the reactor of the catalyst G.

Example 7 Catalyst 10 impregnated and dried in the same manner as in Comparative Example 1
g into a rotary kiln and water at a temperature of 500 ° C.
0.7 ml / min (liquid equivalent)
Steam treatment was performed for 1 hour in an atmosphere of 0% to obtain a catalyst H. After 1 g of the catalyst H was reduced at 500 ° C. for 1 hour, the reaction was evaluated. Table 1 shows the chlorine content of the catalyst H, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the outlet of the reactor. Example 8 In Example 7, instead of performing steam treatment in an atmosphere of 100% moisture, air having a moisture of 60% was replaced with 1.4 liter / air.
Catalyst I was obtained in the same manner as in Example 7, except that the steam treatment was performed by supplying the catalyst in minutes. 1 g of this catalyst I
After the time reduction treatment, the reaction was evaluated. Table 1 shows the chlorine content, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the reactor outlet of the catalyst I.

Example 9 1 g of the catalyst A obtained in Comparative Example 1 was charged into a reactor, and
At 0 ° C, water is passed while flowing hydrogen at 148 ml / min.
The solution was supplied at a rate of 0.03 ml / min (in terms of liquid) and subjected to a steam treatment for 15 minutes to obtain a catalyst J. After the temperature of the catalyst J was lowered to the reaction temperature, the reaction was evaluated. Chlorine content of catalyst J, CO adsorption amount and C in hydrogen-containing gas at reactor outlet
Table 1 shows the O concentration. Example 10 A catalyst K was obtained in the same manner as in Example 9 except that the steam treatment was performed for 30 minutes. After the temperature of the catalyst K was lowered to the reaction temperature, the reaction was evaluated. Table 1 shows the chlorine content of the catalyst K, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the outlet of the reactor.

Example 11 A catalyst L was obtained in the same manner as in Example 9 except that the steam treatment was performed for I hour. After the temperature of the catalyst L was lowered to the reaction temperature, the reaction was evaluated. Table 1 shows the chlorine content of the catalyst L, the CO adsorption amount, and the CO concentration in the hydrogen-containing gas at the outlet of the reactor.

[0039]

[Table 1]

[0040]

According to the present invention, the halogen content in the catalyst can be reduced without deterioration of the catalyst, and as a result, the dispersibility of the metal component can be improved, and the CO in the hydrogen-containing gas can be efficiently reduced. C that can be selectively oxidized and removed and can avoid corrosion of manufacturing equipment such as peripheral equipment and piping systems
O removal catalyst, and CO in hydrogen-containing gas using the same, particularly in a hydrogen-containing gas that can be suitably used for a fuel cell
And a method for producing a hydrogen-containing gas for removing hydrogen.

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Claims (6)

[Claims] 1. A CO removal catalyst comprising at least a ruthenium component supported on a titania-alumina carrier, wherein the halogen content is 0.2% by weight or less and the CO adsorption amount is 10 μmol / g or more. A CO removal catalyst for removing CO in a hydrogen-containing gas. 2. The CO removal catalyst according to claim 1, wherein an alkali metal and / or an alkaline earth metal is further supported on the titania-alumina carrier. 3. The CO removal catalyst according to claim 1, wherein the halogen content is 0.1% by weight or less. 4. The CO removal catalyst according to claim 1, wherein the weight ratio of titania to alumina in the titania-alumina carrier is in the range of 0.1: 99.9 to 90:10. 5. The CO removal catalyst according to claim 1, wherein the halogen is chlorine. 6. The CO removal catalyst according to claim 1, wherein the hydrogen-containing gas is a hydrogen-containing gas for a fuel cell.