JP2003012303A - Hydrogen refining unit, hydrogen refining catalyst and its carrier, and production method of the carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen refining unit which converts CO in a hydrogen rich gas obtained by steam reforming of hydrocarbons into hydrogen at a high conversion rate by steam and oxygen, and to provide a catalyst built-in the unit, and its catalyst carrier and its production method. SOLUTION: The hydrogen refining unit which reduces CO by using a carbon monoxide reforming and hydrogen refining catalyst, receiving a supply of a reformed gas containing hydrogen gas, carbon monoxide and steam, is provided. The hydrogen refining catalyst is composed of loading a catalyst material on an extrusion integrated molding whose main component is a transition alumina containing a hydroxy group. A carrier for hydrogen refining catalyst is the extrusion integrated molding. The carrier is produced through drying and firing process after extruding the mixture of powder containing re-hydrated alumina and combustible materials as raw materials, and then retaining in a wet atmosphere or water of more than 110 deg.C and re-hydrating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen purifying apparatus, a hydrogen purifying catalyst, and a carrier thereof for purifying a reformed gas containing hydrogen as a main component and containing CO to provide a hydrogen rich gas having a low CO content. The present invention relates to a method for producing the carrier.

[0002]

2. Description of the Related Art As a hydrogen source for a fuel cell or the like, a hydrogen-rich reformed gas obtained by reforming a hydrocarbon or a fuel amount such as alcohol or ether is used. In the case of a polymer electrolyte fuel cell, the platinum catalyst used for the electrode may be poisoned by CO contained in the reformed gas. When the platinum electrode catalyst of the fuel cell is poisoned, the electrochemical reaction of hydrogen that occurs in the fuel cell is hindered and the power generation efficiency of the fuel cell is significantly reduced. Therefore, it is necessary to remove CO in the reformed gas.

In order to explain the reason why CO is present in the reformed gas, a steam reaction when methanol is used as a fuel will be shown below.

[Chemical 1] The steam reforming reaction of methanol is performed by the methanol-reforming reaction represented by the formula (1).
It is considered that the hydrogen decomposition gas and the CO conversion reaction represented by the formula (2) proceed at the same time, and the reaction represented by the formula (3) occurs as a whole to generate a hydrogen-rich gas containing carbon dioxide. If these reactions are carried out completely, no CO will eventually be produced. When actually proceeding the reforming reaction, it is difficult to completely carry out the reaction of the above formula (2), so CO is a by-product in the reformed gas reformed by the fuel reformer. Included in trace amounts.

Usually, in order to remove CO, CO and steam are subjected to a shift reaction in a CO shift section equipped with a CO shift catalyst to convert them into carbon dioxide and hydrogen to reduce the CO concentration,
After that, a small amount of air is introduced to selectively oxidize CO to remove CO. Conventionally, a copper-zinc catalyst or a copper-chromium catalyst has been used as a CO conversion catalyst, and it has been carried out at a reaction temperature of 200 to 230 ° C.
In recent years, a copper oxide-aluminum oxide spinel structure type catalyst (JP-A-56-158147) and a catalyst in which Pt is supported on a metal oxide (JP-A-2000-302410) are also known.

However, these catalysts are used in the form of pellets or coated on a ceramic base or a metal base. When used in the form of pellets or packed in a column or the like, a gas supply device having a large capacity is required because the pressure loss during the reaction is large. It is also used in a form coated on a ceramic base or a metal base. However, in this case, the amount of catalyst charged in the reactor is reduced and a predetermined reaction rate is obtained, so that the device becomes large. Further, there is a problem that the catalyst layer falls off from the base.

[0006] Further, in Japanese Patent Laid-Open No. 2000-302410, it has been proposed to form an oxide carrier into a honeycomb shape to be used as a catalyst, but α-alumina which is a perfect oxide has a specific surface area of 50.
m ² / g or more things there is a limit to the high activation not obtained.

[0007]

As described above, in the prior art, it was not possible to make the shift conversion section of the hydrogen purification apparatus compact and the apparatus became large, and satisfactory performance could not be obtained. Further, cooling of the gas was necessary to improve the reaction activity.

The present invention is directed to downsizing of a hydrogen purifier,
We have found a highly active catalyst with a small CO shifter and a small pressure loss, and have been able to convert CO gas in hydrogen-rich gas obtained by steam reforming of hydrocarbons into high-conversion hydrogen by steam and oxygen. The purpose of the present invention is to provide a device, a catalyst incorporated in the device, a catalyst carrier and a method for producing the same.

[0009]

In order to solve the above-mentioned problems, the inventors of the present invention used a CO
As a result of intensive research to find a highly active catalyst with a compact converter and low pressure loss, a catalyst formed by supporting a catalytic substance on an extruded integrally formed body whose main component is a transition alumina having a hydroxyl group is a hydrogen-rich gas. They have found that they are suitable for the conversion of CO in steam and oxygen, and have completed the present invention.

That is, the gist of the present invention is as follows. (1) A hydrogen purification apparatus that receives hydrogen gas and a reformed gas containing carbon monoxide and steam and reduces carbon monoxide by using a carbon monoxide shift / hydrogen purification catalyst, The catalyst for metamorphic / hydrogen purification is a hydrogen purification apparatus characterized in that a catalyst substance is supported on an extruded integrally molded body whose main component is a transition alumina material having a hydroxyl group. (2) A catalyst for hydrogen purification, characterized in that a catalyst substance is supported on an extruded integrally molded body whose main component is a transition alumina having hydroxyl groups. (3) A carrier for a catalyst for hydrogen purification, which is an extrusion-integrated molded body whose main component is a transition alumina having hydroxyl groups. (4) A mixture of powder containing rehydratable alumina and a combustion substance is extruded as a raw material, then held in a wet atmosphere at 110 ° C or higher or in water for rehydration, followed by a drying and firing step. A method for producing a carrier for a catalyst for hydrogen purification, which is characterized in that

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The present invention provides a hydrogen purifier that purifies a reformed gas containing hydrogen as a main component and CO to provide a hydrogen-rich gas having a low CO content. In the present invention, it is essential that the hydrogen purifying apparatus be loaded with a catalyst having a catalytic substance supported on an extruded integrally formed body whose main component is a transition alumina material having a hydroxyl group. It is essential that the hydrogen purifier be equipped with a raw material supply unit, a shift catalyst reaction chamber, and a purified gas outlet. The shift conversion catalyst reaction chamber may have a heating unit to keep the reaction temperature at a constant temperature, or may have a heat exchanger. Further, a small amount of air may be supplied to the inside of the hydrogen purifier to simultaneously carry out the CO partial oxidation reaction. The fuel used to generate the reformed gas containing hydrogen as a main component and containing CO is supplied to the hydrogen purifier, but is not particularly limited, and there are natural gas, methanol, gasoline and the like, and the reforming method is steam adding steam. There are reforming and partial oxidation reforming performed by adding air to steam.

Next, the carrier and catalyst of the present invention and the method for producing the same will be described. The catalyst carrier of the present invention is characterized in that the main component is a transition alumina having a hydroxyl group. Transition alumina is in the form of ρ, η, γ, χ, θ by X-ray analysis,
The amount of water of crystallization is usually 0.02 to 0 per mol of surface hydroxyl groups.
Have 5 mol. The amount of surface hydroxyl groups is calculated from the loss on ignition. The α-alumina form, which is an oxide having no surface hydroxyl group, or the amount of hydroxyl group was less than 1% (corresponding to 0.06 mol) as the loss on ignition, the shift reaction activity was low for unknown reasons. It is considered that the hydroxyl groups on the surface of the carrier improve the affinity of the shift reaction with water vapor.

The transitional alumina-based carrier is characterized in that it is an extruded integrally molded body. The shape includes a so-called honeycomb structure having 50 to 1000 openings per square inch, a nuddle shape obtained by bundling thread-like extruded products, a sponge shape that is a porous extruded product, etc. It is recommended because the body has a rectification mechanism for the reaction gas. The cross-sectional shape of the openings of the honeycomb structure is not particularly limited and may be circular, hexagonal, quadrangular or the like.

In the present invention, the transition alumina carrier is extruded from a powder containing rehydratable alumina as a raw material, and then is extruded and kept in a wet atmosphere at 110 ° C. or higher or in water for rehydration, followed by a drying and firing step. It is characterized by performing. Rehydratable alumina is ρ-alumina or amorphous alumina that reacts with water to form alumina hydrate.In industrial use, gibbsite crystal aluminum hydroxide, which is aluminum trihydroxide obtained from the Bayer process, is temporarily used. Obtained by baking. The instantaneous calcination is typically a firing atmosphere temperature of about 500 ° C. to 1200 ° C. and a linear velocity of about 5 m / sec.
Contact time of about 0.1 when entrained in an air flow of about 50 m / sec.
It is carried out by firing up to 3 to 10% by weight of ignition loss under the condition of seconds to about 10 seconds. The powder calcined in an air stream is usually separated and collected from the air stream by a known method such as a cyclone, a bag filter and an electrostatic precipitator. Simultaneously with separation and recovery, or after cooling, a rehydratable alumina is obtained.

The at least partially rehydratable alumina thus obtained for use in molding is
Loss on ignition 3-10% by weight, BET specific surface area 100 m ²
/ G or more, the crystal form main component is χ, ρ-alumina. The at least partially rehydratable alumina thus obtained is mixed with combustible material and then with water for extrusion.

In the present invention, the aggregate composition other than rehydratable alumina is not particularly limited as long as the catalytic performance is not impaired, and α-alumina, silica, alumina hydrate, clay,
Inorganic substances such as talc, bentonite, clay, diatomaceous earth, zeolite, cordierite, titania, zirconia, silica sol, alumina sol, mullite and glass can be added. Ceramic fibers or whiskers may be added as a strength improver.

In the present invention, it is essential to add a combustible substance in order to secure the pore volume of the transition alumina compact. Examples of combustible substances are wood chips, cork granules, coal dust, activated carbon, charcoal, crystalline cellulose powder, starch, sucrose, gluconic acid, polyethylene glycol, polyvinyl alcohol.
And polyacrylamide, polyethylene, polystyrene and the like, and mixtures thereof. The larger the amount of the above-mentioned combustible substance added, the larger the pore volume and the higher the catalytic activity. However, if too much is added, the strength will decrease.

The mixture of rehydrated alumina and aggregate or combustible substance must be partially or completely coated with a rehydration inhibitor prior to mixing and kneading with water or a water-containing substance. If you do not coat it with a rehydration inhibitor and directly contact water or a water-containing substance, a rehydration reaction of rehydratable alumina will occur, which will cure in the extrusion molding machine and make it impossible to mold, the target extrusion molding I can't body.

As a rehydration inhibitor, during extrusion molding,
It is only necessary to prevent the behavior of water and rehydratable alumina that cause a rehydration reaction and make it impossible to mold.Specifically, a substance that is solid at room temperature and is lost as a liquid by heating, or a surface such as a surfactant Good coating material. More specifically, caproic acid, palmitic acid, oleic acid, gluconic acid, caprylic acid, stearic acid, salicylic acid, trimethylacetic acid,
Examples thereof include fatty acids such as lauric acid and salts thereof, alcohols such as lauryl alcohol and stearyl alcohol, amines, aromatic compounds and natural polymer compounds. An ordinary mixer, a crusher, or a kneader can be used to add the rehydration inhibitor.

In the present invention, a known binder is used as a molding aid. Examples thereof include polyvinyl alcohol, starch, cellulose and the like.

The extrusion raw material to which the rehydration inhibitor is added is kneaded with water or a water-containing substance together with a binder or the like to form a plastic kneaded material, and is subjected to extrusion molding. As the extrusion molding means, an ordinary extrusion molding machine can be used,
The mechanism is not particularly limited. A die having a honeycomb shape can be attached to the extrusion outlet of the extrusion molding machine for extrusion. As the dice, known ones disclosed in JP-A-48-55960 can be used. The outer shape and cell shape of the extruded body may be any geometrical shape such as square, triangle, hexagon, and circle, and the number of cells, cell wall thickness, cell size, and extruded product length The size is arbitrarily determined.

The extruded extrudate is then rehydrated to increase its mechanical strength. The rehydration treatment is carried out by holding in water vapor or a water vapor-containing gas at about 110 to 200 ° C. for rehydration. It is recommended to carry out a rehydration treatment in preliminary water before the rehydration treatment. Pre-water rehydration treatment is 80
By holding in water for a certain time or more, the rehydration inhibitor can be dissolved and separated from the extruded product while rehydrating. The rehydration in preliminary water may be performed for a sufficient time for the rehydration inhibitor to be eluted, and is usually performed for about 1 hour to about 10 hours. After that, it is preferably held in steam or steam-containing gas at 110 ° C to 200 ° C for rehydration. Rehydration is generally about 10 minutes to 1 week, preferably about 1
Time to about 10 hours. During this process, the rehydratable alumina is substantially completely rehydrated to boehmite crystalline aluminum hydroxide. The longer the rehydration time and the higher the temperature, the greater the mechanical strength. However, if the rehydration time is 200 ° C. or higher, expensive pressure resistant equipment is required, which is not economical. When the rehydration temperature is less than about 110 ° C, the mechanical strength of the obtained transition alumina support is low.

The rehydrated molded body is subsequently dried and calcined to remove the attached water in the molded body to obtain a transition alumina carrier having a predetermined hydroxyl group. The firing temperature is usually 300 to 10
The temperature is 00 ° C, preferably 400 to 700 ° C, and the firing temperature may be selected depending on the target loss on ignition of the molded product or the specific surface area. Firing is performed by combustion gas, indirect heating with an electric heater, infrared heating, or the like. It is also possible to remove the attached water by a method such as natural drying, hot air drying, or vacuum drying prior to firing.

The transitional alumina extruded integrally formed body of the present invention thus obtained usually has a BET specific surface area of about 100 m ² / g, a pore volume of about 0.30 cm ³ / g or more, and an ignition loss of 1% or more. And a honeycomb structure having a hydroxyl group.

The hydrogen purification catalyst of the present invention is characterized in that the above-obtained transition alumina molded body is loaded with or contains a catalyst component. As the supporting metal, Ni, Pd, Pt, C
Group 8 elements such as o, Rh, Ir, Fe, Ru, Os, and C
1B group elements such as u, Ag, Au, 2B of Zn, Cd, Hg
At least one metal selected from the group metals and oxides thereof is used. As a method for loading these catalyst components on the catalyst carrier, a known method such as an ordinary impregnation method or a spray method can be used. It is also possible to add a catalyst component to the extrusion molding process.

[0026]

According to the present invention described in detail above, a highly active carrier for a hydrogen purification catalyst for purifying a reformed gas containing hydrogen as a main component and containing CO to provide a hydrogen rich gas having a low CO content. And, the hydrogen purification catalyst, the apparatus and the manufacturing method have been found, and the industrial value thereof is extremely large.

[0027]

The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited by the examples. The BET specific surface area, ignition loss and pore volume were measured by the following methods. BET specific surface area (m ² / g): measured using a direct reading specific surface area measuring device Monosorb manufactured by Cantachrome. Burning loss (%): 110 according to JIS-H1901
It was calculated from the weight loss after heating at 0 ° C. for 2 hours. Pore volume (cm ³ / g): Measured by Hg press-fitting method (Cantachrome, Autoscan 33 type, porosimeter).

Example 1 Dry gibbsite aluminum hydroxide (water content: 1% or less) obtained from the buyer process was put into a hot gas stream at about 700 ° C. and instantaneously calcined. The material that was instantaneously calcined was a rehydrating alumina whose burning material was 7% and whose crystal form was represented by χ and ρ.

2 parts by weight of stearic acid was added to 100 parts by weight of the rehydratable alumina powder, and the mixture was mixed for 2 hours with a crusher to coat the surface of the rehydratable alumina with stearic acid and then 28 parts by weight of cordierite powder. Parts, 14 parts by weight of ceramic fiber, 8.3 parts by weight of methyl cellulose and 51 parts by weight of water, and after kneading with a kneading machine for 30 minutes, it is supplied to a screw-type extruder and has a wall thickness of 0.4 mm and a side of 2 mm. 70mm x 70mm with a square cell unit of about 50mm long
A honeycomb molded body of was obtained.

Next, this extruded body was immersed in warm water at about 90 ° C. for 1 hour to carry out preliminary rehydration for 12 hours. At this time, stearic acid floated on the surface of the hot water and was removed from the honeycomb formed body. Next, the pre-rehydrated honeycomb was placed in a glass beaker and transferred to a stainless steel 5 liter autoclave. Water was separately charged, and the mixture was kept under saturated steam at 130 ° C for 4 hours for rehydration.

This aged product was placed in an electric furnace and heated to 500 ° C. at 100 ° C./hour and held for 2 hours. When the crystal form of the fired product thus obtained was investigated, it was found that the main component was γ-alumina, which is transition alumina. The physical properties of the thus-obtained carrier containing transition alumina as a main component are shown in Table 1.

A hydrorefining catalyst was obtained by the following method using the extruded body containing the transition alumina as a main component as a carrier.
First, 12 mm × so that the carrier honeycomb can be loaded into the reaction tube.
It was cut out to a length of 12 mm and a length of 50 mm (7.2 cm ³ ).
By determining the water absorption rate of the carrier honeycomb in advance and adjusting the concentration so that the supported amount is 1 g per liter of honeycomb as the platinum element, the watch glass is impregnated with the dinitodiamine platinum nitric acid solution for the water absorption rate. Supported platinum. The impregnated product is then dried at 150 ° C for 2 hours and then 20
The temperature was raised to 500 ° C. at a heating rate of 0 ° C./hour, and the temperature was maintained at 500 ° C. for 2 hours to obtain a catalyst.

This catalyst was packed in a columnar reactor having a cross section of 13 mm × 13 mm with the catalyst honeycombs stacked in two stages in the flow direction, and after catalyst reduction in hydrogen at 400 ° C. for 30 minutes, the inlet temperature was 4
Carbon monoxide 1.5%, carbon dioxide 12.5% at 00 ° C,
A reforming catalyst model gas consisting of 25% steam, 37.5% hydrogen, and the balance nitrogen was introduced at a space velocity of 1600 [1 / hr],
The carbon monoxide conversion was measured. The results are shown in Table 1.
The carbon monoxide conversion rate is the CO concentration A in the model gas put in the reactor and the CO concentration B in the gas discharged from the reactor.
Was measured and determined by the following formula. Carbon monoxide conversion rate (%) = (A−B) / A × 100

Example 2 An extruded carrier was obtained in the same manner as in Example 1 except that the firing temperature was 700 ° C. When the crystal form of the thus obtained fired product was investigated, the main component was γ-alumina. The physical properties of the thus obtained carrier are shown in Table 1. Further, a catalyst supporting Pt 1 g / l was prepared in the same manner as in Example 1 and the carbon monoxide conversion rate was measured. The results are shown in Table 1.

Comparative Example 1 An extruded carrier was obtained in the same manner as in Example 1 except that the firing temperature was 1100 ° C. When the crystal form of the thus obtained fired product was investigated, the main component was α-alumina. The physical properties of the thus obtained carrier are shown in Table 1. Also, Pt 1 g / l was prepared by the same method as in Example 1.
A supported catalyst was prepared and the carbon monoxide conversion rate was measured. The results are shown in Table 1.

Comparative Example 2 0.5 liter of purified water was placed in a beaker having a volume of 2 liter, and commercially available transition alumina (Puralox manufactured by CONDEA Co., Ltd. was used.
SCFa-250) 300g, nitric acid is added with stirring to adjust the pH to pH 4, and commercially available transition alumina is dispersed into a slurry.
Was produced. A commercially available 600 cel cordierite honeycomb which had been calcined at 500 ° C. for 2 hours was immersed in the slurry and then pulled up. After calcining at 500 ° C. for 2 hours, the weight was measured to determine the coating amount. Soaking and calcination were repeated until the coat amount reached 150 g / liter to obtain a coat carrier. A catalyst supporting Pt 1 g / l was prepared on this carrier in the same manner as in Example 1, and the carbon monoxide conversion rate was measured. The results are shown in Table 1.

Comparative Example 3 Example directly on a commercially available 600cel cordierite honeycomb carrier
A catalyst carrying Pt 1 g / l was prepared in the same manner as in 1, and the carbon monoxide conversion rate was measured. The results are shown in Table 1.

[Table 1]

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 35/04 B01J 35/04 301P B28B 3/20 B28B 3/20 K C04B 35/10 H01M 8/06 G H01M 8 / 06 C04B 35/10 BF term (reference) 4G030 AA36 AA61 AA66 BA34 CA01 CA04 CA10 GA01 GA07 GA08 GA14 GA21 HA18 4G040 EB31 EB32 4G054 AA06 AB09 BD02 BD19 4G069 AA01 AA08 BA01A BA01B CC26 CC40 EC06XXEC03 EC03 EC05 EC02 EC03 EC03 EC02 EC03 EC02 EC03 EC03 EC03 EC02 EC03 EC02 EC03 EC03 EC03 EC03 EC22Y EC30 FA01 FB30 FB67 FC07 5H027 AA06 BA01 BA17

Claims (5)

[Claims] 1. A hydrogen purification apparatus which receives hydrogen gas, a reformed gas containing carbon monoxide and steam, and reduces carbon monoxide by using a carbon monoxide shift / hydrogen purification catalyst. A catalyst for carbon oxide conversion / hydrogen purification is a hydrogen purification apparatus characterized in that a catalyst substance is supported on an extruded integrally formed body whose main component is a transition alumina material having a hydroxyl group. 2. A catalyst for hydrogen purification, characterized in that a catalyst substance is supported on an extruded integrally formed body whose main component is a transition alumina material having a hydroxyl group. 3. A carrier for a catalyst for hydrogen purification, which is an extrusion-integrated molded body whose main component is a transition alumina having hydroxyl groups. 4. A BET specific surface area of 100 m ² / g or more and a pore volume of
4. The carrier for hydrogen purifying catalyst according to claim 3, wherein the main component is a transition alumina containing 0.30 cm ³ / g or more and having a honeycomb-shaped hydroxyl group content of 5% or more as an ignition loss. 5. A mixture of a powder containing rehydratable alumina and a combustible substance is used as a raw material and is extruded, and thereafter, 11
A method for producing a carrier for a catalyst for hydrogen purification, which comprises holding in a moist atmosphere of 0 ° C. or higher or in water and rehydrating, followed by a drying and firing step.