JP2010094664A - Catalyst for selectively removing carbon monoxide and method of selectively removing carbon monoxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of selectively removing carbon monoxide, in particular, selectively removing carbon monoxide at 100°C or less, from a gas containing hydrogen and carbon monoxide less than the hydrogen. <P>SOLUTION: The method of selectively removing carbon monoxide comprises a process of allowing a mixed gas obtained by mixing gas containing oxygen to the gas containing hydrogen and carbon monoxide less than the hydrogen to contact with a catalyst which carries three components of a noble metal (1), at least one kind (2) selected from a group consisting of nickel, cobalt and iron and at least one kind (3) selected from a group of magnesium, calcium, barium and rare earth metal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a catalyst for selectively removing carbon monoxide from a gas containing hydrogen and carbon monoxide and a method thereof. In particular, the present invention relates to a catalyst for selectively removing carbon monoxide from a reformed gas containing hydrogen monoxide as a main component obtained from various hydrogen production fuels by steam reforming and the like, and a method thereof.

  The fuel cell is expected as a next-generation power generation system that obtains clean energy. Fuel cells have excellent characteristics such as high power generation efficiency, no generation of harmful substances, low noise and vibration, and the ability to produce hydrogen as fuel from various raw materials.

  Among fuel cells, solid polymer fuel cells that use a solid polymer membrane as an electrolyte operate at a low temperature of 100 ° C. or lower and are relatively small, so that they can be used in distributed household power supplies, fuel cell vehicles, and portable devices. It is particularly expected as a power source.

  Hydrogen used as fuel for fuel cells is separated from the hydrogen-containing by-product gas discharged from the industry, various hydrocarbons such as methane, natural gas, liquefied natural gas, naphtha, kerosene and light oil, and alcohol such as methanol. It can be produced by a method that is chemically obtained from a kind, a method by decomposition of water, or the like. At present, hydrogen can be obtained by a method of steam reforming fossil fuels, mainly natural gas, because they can be easily manufactured at low cost.

  In the polymer electrolyte fuel cell, a platinum-containing catalyst is used for the electrode. It is known that the platinum-based electrode catalyst is easily poisoned with carbon monoxide, and in particular, it is very small at low temperatures and the power generation efficiency is greatly reduced. In order to take advantage of the low temperature operability of the polymer electrolyte fuel cell, it is necessary to reduce the concentration of carbon monoxide in hydrogen as a fuel to 100 ppm or less, preferably 10 ppm or less.

  Steam reforming of natural gas such as methane produces carbon monoxide along with hydrogen. Furthermore, carbon monoxide reacts with water vapor (water shift reaction; equilibrium reaction) to generate carbon dioxide and hydrogen. The resulting reformed gas contains hydrogen at a high ratio, but also contains about 1 to 10% of carbon monoxide. Thus, in order to make the reformed gas usable as a fuel for the polymer electrolyte fuel cell, a technique for further reducing the carbon monoxide concentration has been studied. Among them, a technique for oxidation to carbon dioxide (particularly, carbon monoxide selective oxidation that consumes as little hydrogen as fuel) has become effective, and it has been adopted in some polymer electrolyte fuel cells that are commercially available.

  Oxidation of carbon monoxide is an exothermic reaction and requires a cooling device to adjust the temperature. On the other hand, if a high temperature (eg, 120 ° C or higher) is required to obtain a sufficient oxidation reaction rate, a heating device must be provided. I must. Therefore, it is preferable that the selective oxidation catalyst for carbon monoxide in the hydrogen-containing gas has a low-temperature activity (for example, 100 ° C. or less) such that selective oxidation proceeds spontaneously by the heat of oxidation reaction.

  In order to achieve the above-described problems, a catalyst in which a noble metal such as platinum, ruthenium, or rhodium is supported on a support mainly made of an inorganic oxide has been studied.

  Patent Document 1 discloses that when carbon monoxide is selectively oxidized from a gas containing about 20 to 98% by volume of hydrogen, about 0.01 to 2% by volume of carbon monoxide, and the balance containing nitrogen. A method for selectively removing carbon monoxide is disclosed, wherein oxygen having a molar ratio to carbon of 1 to 3 is supplied and contacted with a catalyst supporting platinum at about 100 to 200 ° C.

  Patent Document 2 discloses that a feed gas rich in hydrogen compared to carbon monoxide is 120 ° C. or lower, preferably 100 ° C. or lower in the presence of a catalyst in which at least one selected from rhodium and ruthenium is dispersed on a support. And a method for selectively removing carbon monoxide, characterized by reacting with oxygen. On the other hand, when a catalyst in which platinum is supported on alumina is used, the conversion rate of carbon monoxide at 100 ° C. or lower is low compared to a catalyst in which rhodium or ruthenium is supported (see Comparative Example A, FIG. 3). Furthermore, it is described that the production of water by oxidation of hydrogen is large and the selectivity of the oxidation reaction is low (see Comparative Example I, FIG. 5).

  In order to solve the above-described problems caused when an attempt is made to selectively oxidize and remove carbon monoxide in a mixed gas containing hydrogen and carbon monoxide less than hydrogen in the presence of a platinum-supported catalyst at 100 ° C. or lower. Various studies have been made.

  Patent Document 3 discloses a CO selective catalyst containing platinum and at least one transition metal other than platinum, wherein the transition metal exists in a plurality of oxidation states.

  Patent Document 4 discloses a CO selective oxidation catalyst in which a catalyst layer containing an active oxygen supply material capable of oxidizing CO such as a noble metal and an alkali metal compound, an alkaline earth metal compound, or a rare earth metal compound is coated. .

  Claim 5 of Patent Document 5 includes a CO selective oxidation catalyst in which at least one selected from platinum and alkali metals, alkaline earth metals, rare earth metals, manganese, iron, cobalt, nickel or copper is supported on an inorganic carrier. It is disclosed.

  However, all of these were insufficient as catalysts for selective removal of carbon monoxide used at 100 ° C. or lower.

US Pat. No. 3,216,783 Japanese Patent Laid-Open No. 5-201702 JP 2004-049961 A JP 2003-154266 A JP 2003-284948 A

  The problem to be solved by the present invention is a method of selectively oxidizing and removing carbon monoxide from hydrogen and a gas containing less carbon monoxide than hydrogen, and in particular, selectively carbon monoxide at 100 ° C. or lower. It is to provide a catalyst for removal and a method thereof.

  As a result of intensive studies to solve the above problems, the present inventor has, as a carbonaceous support, at least one selected from the group consisting of (1) noble metal, (2) nickel, cobalt and iron, and ( 3) The present inventors have found that a catalyst supporting at least one three component selected from the group consisting of magnesium, calcium, barium and rare earth metals is extremely useful, and based on this finding, the present invention has been completed.

  That is, the first invention related to the catalyst for selective removal of carbon monoxide includes: (1) a noble metal, (2) at least one selected from the group consisting of nickel, cobalt and iron, and (3) magnesium. Further, at least one three component selected from the group consisting of calcium, barium and rare earth metals is supported.

  A second invention relating to a catalyst for selectively removing carbon monoxide is characterized in that the carbonaceous carrier is at least one selected from the group consisting of carbon nanotubes, carbon nanofibers and fullerenes.

  A third invention relating to a catalyst for selective removal of carbon monoxide is characterized in that the carbonaceous support is a carbon nanotube.

  A fourth invention relating to a catalyst for selectively removing carbon monoxide is characterized in that the noble metal is at least one selected from the group consisting of platinum, ruthenium, rhodium and gold.

  A fifth invention relating to a catalyst for selective removal of carbon monoxide is characterized in that the noble metal is platinum.

  A sixth invention relating to a catalyst for selectively removing carbon monoxide is characterized in that a noble metal, nickel and magnesium are supported on a carbonaceous support.

  According to a seventh invention relating to a method for selectively removing carbon monoxide, in the first to sixth inventions, a mixed gas obtained by mixing oxygen and a gas containing hydrogen and a gas containing less carbon monoxide than hydrogen is used. It is made to contact with the catalyst for selective removal of carbon monoxide.

  An eighth invention relating to a method for selectively removing carbon monoxide is characterized in that the content of carbon monoxide in the gas containing hydrogen and carbon monoxide less than hydrogen is 10% by volume or less. It is.

  According to a ninth aspect of the method for selectively removing carbon monoxide, the temperature at which the mixed gas and the catalyst are brought into contact with each other is 20 to 100 ° C.

  A tenth aspect of the method for selectively removing carbon monoxide is characterized in that the water vapor content in the mixed gas is less than a saturated water vapor pressure at a temperature at which the mixed gas is brought into contact with the catalyst.

  An eleventh invention relating to a method for selectively removing carbon monoxide is characterized in that the gas containing hydrogen and carbon monoxide less than hydrogen is a fuel gas for a fuel cell.

  According to the method for selectively removing carbon monoxide of the present invention, a gas containing hydrogen and a gas containing less carbon monoxide than hydrogen is selectively oxidized at a low temperature of 100 ° C. or less and substantially without consuming hydrogen. Carbon can be oxidized and removed.

The graph which shows the conversion of Example 1, the relationship of a selectivity, and temperature. The graph which shows the conversion of Example 2, the relationship of a selectivity, and temperature. The graph which shows the conversion of Example 3, the relationship of a selectivity, and temperature. The graph which shows the conversion of the comparative example 1, the relationship of a selectivity, and temperature. The graph which shows the conversion of the comparative example 2, the relationship of a selectivity, and temperature. The graph which shows the conversion of the comparative example 3, the relationship of a selectivity, and temperature. The graph which shows the conversion of the comparative example 4, the relationship of a selectivity, and temperature.

  The catalyst for selective removal of carbon monoxide and the method for selective removal of carbon monoxide of the present invention will be described below.

  First, the catalyst for selective removal of carbon monoxide which is one of the present invention will be described.

  The catalyst for selective removal of carbon monoxide of the present invention comprises (1) a noble metal, (2) at least one selected from the group consisting of nickel, cobalt and iron, and (3) magnesium, calcium, It is a catalyst that carries at least one kind of three components selected from the group consisting of barium and rare earth metals as essential components (hereinafter, the components (1), (2), and (3) may be collectively referred to as catalyst components). ).

  As the noble metal in the component (1), platinum, ruthenium, rhodium, palladium, gold, silver and the like can be listed, and plural kinds of noble metals may be supported. Platinum, ruthenium, rhodium and gold are preferred because of their excellent activity at low temperatures. More preferably, it is platinum.

  As at least one selected from the group consisting of nickel, cobalt and iron in the component (2), nickel is preferable.

  Examples of the rare earth metal in the component (3) include lanthanum, cerium, praseodymium, and samarium. As at least one selected from the group consisting of magnesium, calcium, barium and rare earth metals, it is preferable to contain magnesium.

  Examples of the carbonaceous carrier include activated carbon, carbon black, graphite, carbon nanotube, carbon nanofiber, and fullerene. Preferred are carbon nanotubes, carbon nanofibers and fullerenes, and more preferred are carbon nanotubes.

  The catalyst of the present invention is selected from the group consisting of (1) a noble metal compound, (2) a compound containing at least one selected from the group consisting of nickel, cobalt and iron, and (3) a group consisting of magnesium, calcium, barium and rare earth metals. The compound containing at least one selected from the above is supported on a carrier and can be obtained by a general method for producing a supported catalyst through washing, drying, reduction and the like. The metals (1) to (3) may be supported simultaneously or individually. Moreover, when carrying individually, the order is not ask | required.

In order to support the noble metal in the component (1), the following noble metal compounds may be used. Examples of the noble metal compound include PtCl ₄ , PtCl ₂ , [Pt (NO ₂ ) ₂ (NH ₃ ) ₂ ], [PtCl ₂ (NH ₃ ) ₂ ], [Pt (acac) ₂ ] (acac: acetylacetonato Ligand), H ₂ [PtCl ₆ ], H ₂ [Pt (OH) ₆ ], K ₂ [PtCl ₆ ], (NH ₄ ) ₂ [PtCl ₆ ], K ₂ [PtCl ₄ ], (NH ₄ ) _{2 [PtCl 4], [Pt (} NH 3) 6] Cl 4, [Pt (NH 3) 4] Cl 2, [Pt (NH 3) 4] (OH) a platinum compound, such as _2, H [AuCl _4] · Gold compounds such as 4H ₂ O, RuCl ₃ .nH ₂ O, Ru ₂ (OH) ₂ Cl ₄ .7NH ₃ .3H ₂ O, [Ru (acac) ₃ ], K ₂ [RuCl ₅ (H ₂ O)] , _{(NH 4)} 2 [RuCl _{(H 2 O)], [} Ru (NH 3) 4] ruthenium compound such as _{Cl 3, RhCl 3 · 3H 2} O, Rh (OH) 3 · 3H 2 O, rhodium compounds such as [Rh _{(acac) 3]} Can be illustrated. Among these noble metal compounds, platinum compounds are preferable, and [Pt (NO ₂ ) ₂ (NH ₃ ) ₂ ] and H ₂ [PtCl ₆ ] are particularly preferable.

  Examples of the nickel compound, cobalt compound, and iron compound used for loading include nitrates, acetates, carbonates, and oxides of each metal. Specifically, nickel nitrate (II), cobalt nitrate (II), iron nitrate (II), nickel acetate (II), cobalt acetate (II), nickel carbonate (II), nickel oxide (II), cobalt oxide ( II). Nitrate is preferred because of its high solubility in water and relatively easy removal of acid radicals.

  Examples of magnesium compounds, calcium compounds, barium compounds, and rare earth metal compounds used for loading include nitrates, acetates, carbonates, and oxides of each metal. Specific examples include magnesium nitrate, calcium nitrate, barium nitrate, lanthanum nitrate (III), cerium nitrate (III), praseodymium nitrate (III), magnesium acetate, calcium acetate, barium acetate, magnesium carbonate, magnesium oxide and the like. . Nitrate is preferred because of its high solubility in water and relatively easy removal of acid radicals.

  The method for supporting the noble metal compound, nickel compound, cobalt compound, iron compound, magnesium compound, calcium compound, barium compound, and rare earth metal compound on the carrier is not particularly limited, but can be supported by a general impregnation method or the like.

  Although the amount of the noble metal supported is not particularly limited, it is usually preferably 0.1 to 20% by weight, particularly preferably 0.3 to 10% by weight as the noble metal with respect to the support. When the amount of noble metal supported is less than 0.1% by weight, the conversion rate of carbon monoxide is low, and even when an amount exceeding 20% by weight is supported, the conversion rate of carbon monoxide and the selectivity of the oxidation reaction are significant. There is no difference and it is not preferable because the catalyst cost only increases.

  The supported amount of nickel, cobalt, and iron is not particularly limited, but usually 0.1 to 20% by weight, preferably 0.3 to 10% by weight, is preferable in combination with nickel, cobalt, and iron with respect to the support. is there. When the combined amount of nickel, cobalt, and iron is less than 0.1% by weight, the conversion rate of carbon monoxide at 100 ° C. or lower is low, and even if an amount exceeding 20% by weight is supported, carbon monoxide There is no significant difference in the conversion rate and selectivity of the oxidation reaction.

  The amount of magnesium, calcium, barium, and rare earth metal supported is not particularly limited, but usually 0.1 to 20% by weight of magnesium, calcium, barium, and rare earth metal is preferably added to the support, and particularly preferably 0.8. 3 to 10% by weight is preferred. In the case where the supported amount of magnesium, calcium, barium, and rare earth metal is less than 0.1% by weight, the conversion rate of carbon monoxide at 100 ° C. or lower is low, and even when an amount exceeding 20% by weight is supported, There is no significant difference in carbon monoxide conversion and oxidation reaction selectivity.

  There are no particular restrictions on the loading conditions, but usually the carbonaceous support and an aqueous solution in which the metal compound containing the catalyst component is dissolved may be brought into contact at room temperature to 90 ° C. for 1 minute to 10 hours.

  After the metal compound containing the catalyst component is supported on the carrier, it is dried at room temperature to 95 ° C. for 30 minutes to 12 hours by natural drying, a rotary evaporator, a blast dryer or the like.

  The method for reducing the catalyst is not particularly limited, but it is usually carried out in a hydrogen stream at room temperature to 400 ° C. for 0.5 to 5 hours.

  The catalyst obtained as described above is brought into contact with a mixed gas obtained by mixing an oxygen-containing gas with a gas containing hydrogen as a main component and containing carbon monoxide to perform a selective oxidation reaction of carbon monoxide. .

  Gases containing hydrogen and less carbon monoxide than hydrogen include methane, natural gas, liquefied natural gas, various hydrocarbons such as naphtha, kerosene and light oil, reformed gas obtained from alcohols such as methanol, ammonia synthesis A gas etc. can be illustrated. When carbon monoxide is to be reduced to 10 ppm or less using the method of the present invention, the concentration of carbon monoxide in the gas to be supplied and the gas containing less carbon monoxide than hydrogen is preferably 10% by volume or less. .

  As the oxygen-containing gas, pure oxygen, air, or oxygen-enriched air is preferably used. It is appropriate to adjust the amount of oxygen-containing gas added so that oxygen / carbon monoxide (molar ratio) is preferably 0.5 to 5, more preferably 1 to 3. When the oxygen / carbon monoxide (molar ratio) is less than 0.5, the conversion rate of carbon monoxide is low, and when it exceeds 5, the oxidation of hydrogen increases, which is not preferable.

  The water vapor content in a mixed gas obtained by mixing an oxygen-containing gas with a gas containing hydrogen as a main component and containing carbon monoxide affects the activity and durability of the catalyst. The water vapor content in the mixed gas is preferably less than the saturated vapor pressure at the temperature in contact with the catalyst. When water vapor exceeding the saturated vapor pressure is contained, water is condensed on the catalyst surface and the conversion of carbon monoxide is lowered, which is not preferable. Specifically, it can be achieved by bringing the mixed gas into contact with the dehydrating agent, or setting the temperature of the outlet where the mixed gas and the catalyst are in contact with each other to be higher than the dew point of the water vapor content in the mixed gas.

  The contact temperature between the mixed gas and the catalyst is preferably 20 to 100 ° C. Most preferably, it is 40-90 degreeC. If it is less than 20 ° C., the conversion rate of carbon monoxide is low, and if it exceeds 100 ° C., oxidation of hydrogen increases, which is not preferable.

  The reaction pressure is usually from normal pressure to 1 MPa, preferably from normal pressure to 0.4 MPa. Even if it is set to exceed 1 MPa, there is no significant difference in the reaction result, which is economically disadvantageous in terms of equipment, and further, the explosion limit is widened and the safety is lowered.

As GHSV (supply volume velocity in the standard state of the mixed gas to be supplied and apparent volume-based space velocity of the catalyst layer to be used), a range of 1000 to 50000 h ⁻¹ is preferable. In less than 1000h ^-1 is economically disadvantageous requires large reactor, because the conversion of carbon monoxide is reduced if it exceeds 50000h ^-1 undesirable.

  The hydrogen-containing gas from which carbon monoxide has been sufficiently removed by the method of the present invention can be suitably used as a fuel for a fuel cell, and can be advantageously used particularly as a fuel for a polymer electrolyte fuel cell.

  Next, examples will be shown and described in more detail, but the present invention is not limited to these examples.

Multi-walled carbon nanotubes (manufactured by Xiamen University) that are Ni-Mg-Pt / CNT (carbon nanotubes) catalyst supports were degassed at room temperature. Carbon nanotubes were added to a dinitrodiaminoplatinum (II) nitric acid aqueous solution containing platinum corresponding to a supported amount of 5% by weight, and stirred at room temperature for about 0.5 hour. To this carbon nanotube dispersion, a nickel nitrate (II) aqueous solution containing nickel corresponding to a supported amount of 3% by weight, and a magnesium nitrate aqueous solution containing magnesium corresponding to a supported amount of 2% by weight are further added at room temperature. Stir for about 10 hours. The solvent was removed by evaporation with a nitrogen stream at 40 ° C., and the mixture was dried by raising the temperature to 200 ° C. in a nitrogen stream.

After 0.8 g of the prepared catalyst was filled in the reaction tube, it was reduced at 200 ° C. for 1 hour in a hydrogen stream. Next, a mixed gas having the following composition was passed through the catalyst layer at a GHSV of about 1600 h ⁻¹ and contacted with the catalyst at 50 to 120 ° C. to carry out an oxidation reaction.

Mixed gas composition CO: 3.0, H ₂ : 20, O ₂ : 1.95, N ₂ : balance (volume%)
The oxygen conversion rate, the carbon monoxide conversion rate, and the carbon monoxide oxidation reaction selectivity (calculated by dividing the carbon monoxide conversion rate by the oxygen conversion rate) are shown in FIG.

A catalyst was prepared in the same manner as in Example 1 except that the Ni—Mg—Pt / graphite catalyst support was graphite.

After 0.8 g of the prepared catalyst was filled in the reaction tube, it was reduced at 200 ° C. for 1 hour in a hydrogen stream. Next, a mixed gas having the following composition was passed through the catalyst layer at a GHSV of about 1600 h ⁻¹ and contacted with the catalyst at 45 to 120 ° C. to carry out an oxidation reaction.

Mixed gas composition CO: 3.0, H ₂ : 20, O ₂ : 1.5, N ₂ : balance (volume%)
FIG. 2 shows the oxygen conversion rate, the carbon monoxide conversion rate, and the carbon monoxide oxidation reaction selectivity.

After suspending Ni-Mg-Pt / activated carbon activated carbon in an aqueous solution of sodium carbonate, nickel chloride hexahydrate containing nickel corresponding to 1% by weight of support, and similarly containing chloride corresponding to 1% by weight of magnesium After the magnesium hexahydrate was added, chloroplatinic acid (VI) acid hexahydrate corresponding to a supported amount of 5% by weight was further added and stirred overnight at room temperature. After heating to 90 ° C. and cooling, sodium formate was added, and the mixture was again heated to 90 ° C. and reduced, followed by washing with filtered water. It dried by heating up to 200 degreeC in nitrogen stream.

After 8.0 g of the prepared catalyst was charged into the reaction tube, it was reduced in a hydrogen stream at 200 ° C. for 1 hour. Next, a mixed gas having the following composition was passed through the catalyst layer at a GHSV of about 1600 h ⁻¹ and contacted with the catalyst at 50 to 120 ° C. to carry out an oxidation reaction.

Mixed gas composition CO: 3.0, H ₂ : 20, O ₂ : 1.5, N ₂ : balance (volume%)
FIG. 3 shows the oxygen conversion rate, the carbon monoxide conversion rate, and the carbon monoxide oxidation reaction selectivity.

(Comparative Example 1)
A catalyst was prepared in the same manner as in Example 1 except that Pt / CNT catalyst nickel and magnesium were not supported on carbon nanotubes (Xiamen University).

After 0.8 g of the prepared catalyst was filled in the reaction tube, it was reduced at 200 ° C. for 1 hour in a hydrogen stream. Next, a mixed gas having the following composition was passed through the catalyst layer at a GHSV of about 1600 h ⁻¹ and contacted with the catalyst at 30 to 120 ° C. to carry out an oxidation reaction.

Mixed gas composition CO: 3.0, H ₂ : 20, O ₂ : 1.5, N ₂ : balance (volume%)
FIG. 4 shows the oxygen conversion rate, the carbon monoxide conversion rate, and the carbon monoxide oxidation reaction selectivity.

(Comparative Example 2)
A catalyst was prepared in the same manner as in Example 1 except that Mg—Pt / CNT catalyst nickel was not supported on carbon nanotubes (Xiamen University).

After 0.8 g of the prepared catalyst was filled in the reaction tube, it was reduced at 200 ° C. for 1 hour in a hydrogen stream. Next, a mixed gas having the following composition was passed through the catalyst layer at a GHSV of about 1600 h ⁻¹ and contacted with the catalyst at 40 to 200 ° C. to carry out an oxidation reaction.

Mixed gas composition CO: 3.0, H ₂ : 20, O ₂ : 1.5, N ₂ : balance (volume%)
FIG. 5 shows the oxygen conversion rate, the carbon monoxide conversion rate, and the carbon monoxide oxidation reaction selectivity.

(Comparative Example 3)
Pt / graphite catalyst A catalyst was prepared in the same manner as in Example 2 except that nickel and magnesium were not supported on graphite, and the supported amount of platinum was 15% by weight.

After 0.8 g of the prepared catalyst was filled in the reaction tube, it was reduced at 200 ° C. for 1 hour in a hydrogen stream. Next, a mixed gas having the following composition was passed through the catalyst layer at a GHSV of about 1600 h ⁻¹ and contacted with the catalyst at 25 to 200 ° C. to carry out an oxidation reaction.

Mixed gas composition CO: 3.0, H ₂ : 20, O ₂ : 1.5, N ₂ : balance (volume%)
FIG. 6 shows the oxygen conversion rate, the carbon monoxide conversion rate, and the carbon monoxide oxidation reaction selectivity.

(Comparative Example 4)
A catalyst was prepared in the same manner as in Example 1 except that the support was titanium oxide (anatase type) and the supported amount of platinum was 1% by weight.

After charging 1.0 g of the prepared catalyst into a reaction tube, it was reduced in a hydrogen stream at 200 ° C. for 1 hour. Next, a mixed gas having the following composition was passed through the catalyst layer at about GHSV of about 4200 h ⁻¹ and contacted with the catalyst at 30 to 120 ° C. to carry out an oxidation reaction.

Mixed gas composition CO: 3.0, H ₂ : 20, O ₂ : 1.5, N ₂ : balance (volume%)
FIG. 7 shows the oxygen conversion rate, the carbon monoxide conversion rate, and the carbon monoxide oxidation reaction selectivity.

  From Examples 1, 2, and 3, a mixed gas obtained by mixing oxygen and a gas containing hydrogen and carbon monoxide less than hydrogen is supported, and a carbonaceous support is loaded with platinum, nickel, and magnesium. It can be seen that when contacting with the catalyst, the oxidation activity of carbon monoxide is high from a low temperature of 40 ° C., and at 100 ° C. or less, carbon monoxide is oxidized with a high selectivity and hydrogen is hardly consumed.

  From Comparative Examples 1, 2, and 3, it can be seen that when a catalyst that does not support platinum, nickel, and magnesium is used, the conversion rate of carbon monoxide is not improved unless the temperature exceeds 100 ° C. .

  From Comparative Example 4, when a catalyst supporting platinum, nickel, and magnesium is used for titanium oxide that is not carbonaceous, the conversion rate of carbon monoxide is not improved unless the temperature exceeds 100 ° C. Recognize.

  An apparatus for selectively removing carbon monoxide based on the method of the present invention is useful for a fuel cell, particularly a polymer electrolyte fuel cell operating at a low temperature.

Claims (11)

  The carbonaceous support includes (1) at least one selected from the group consisting of noble metals, (2) nickel, cobalt and iron, and (3) at least one selected from the group consisting of magnesium, calcium, barium and rare earth metals. A catalyst for selective removal of carbon monoxide, wherein three components are supported.   The catalyst for selective removal of carbon monoxide according to claim 1, wherein the carbonaceous support is at least one selected from the group consisting of carbon nanotubes, carbon nanofibers, and fullerenes.   The catalyst for selective removal of carbon monoxide according to claim 2, wherein the carbonaceous support is a carbon nanotube.   The catalyst for selective removal of carbon monoxide according to any one of claims 1 to 3, wherein the noble metal is at least one selected from the group consisting of platinum, ruthenium, rhodium and gold.   The catalyst for selective removal of carbon monoxide according to claim 4, wherein the noble metal is platinum.   6. The catalyst for selective removal of carbon monoxide according to any one of claims 1 to 5, wherein a noble metal, nickel and magnesium are supported on a carbonaceous support.   In a method in which hydrogen and a gas containing carbon monoxide less than hydrogen are mixed with an oxygen-containing gas and brought into contact with the catalyst to selectively oxidize and remove carbon monoxide to carbon dioxide. A selective removal method of carbon monoxide, which is the catalyst for selective removal of carbon monoxide according to any one of claims 1 to 6.   The method for selectively removing carbon monoxide according to claim 7, wherein the content of carbon monoxide in hydrogen and a gas containing less carbon monoxide than hydrogen is 10% by volume or less.   The method for selectively removing carbon monoxide according to claim 7 or 8, wherein the temperature at which the mixed gas and the catalyst are brought into contact is 20 to 100 ° C.   The method for selectively removing carbon monoxide according to any one of claims 7 to 9, wherein the water vapor content in the mixed gas is less than a saturated water vapor pressure at a temperature at which the mixed gas is brought into contact with the catalyst.   The method for selectively removing carbon monoxide according to any one of claims 7 to 10, wherein the gas containing hydrogen and carbon monoxide less than hydrogen is a fuel gas for a fuel cell.