JP2010195651A - Method for producing hydrogen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing hydrogen with few carbon dioxide emission and excellent energy efficiency. <P>SOLUTION: The water existing in a gas phase and the water-soluble hydrocarbon existing in a liquid phase and having at least two carbon atoms and at least two oxygen-carbon bonds are allowed to react under the presence of a metal-containing catalyst. For example, the water-soluble hydrocarbon is glycerol, glyceraldehyde, glucose, sorbitol or sucrose, and the reaction temperature is ≥100°C and ≤600°C, and the metal is palladium, platinum, nickel, ruthenium, rhodium, cobalt, iron, zinc or rhenium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention, for example, as an energy source for fuel cells, hydrogen engine automobiles, etc., as a raw material used for synthesis of ammonia, methanol, hydrogen peroxide, etc., and further as a material used in semiconductor manufacturing, metallurgy, etc. The present invention relates to a method for producing hydrogen useful for various applications.

  In recent years, with the progress of global warming, development of a technology for reducing global warming gas such as carbon dioxide is desired. Among them, hydrogen is attracting attention as clean energy with low environmental impact. For example, in a fuel cell system using hydrogen or a hydrogen engine vehicle, the byproduct is only water and carbon dioxide is not emitted. However, in practice, hydrogen production generally requires large energy, and there is a problem that a large amount of carbon dioxide is discharged during hydrogen production. For example, in the production of hydrogen by steam reforming reaction of hydrocarbons such as methane, the reaction is a large endothermic reaction, and a high reaction temperature (430 to 880 ° C.) is required to increase the equilibrium conversion rate. Heat is supplied to the reactor. Furthermore, since a catalyst such as Ni / alumina used in the reaction is significantly poisoned by sulfur contained in the raw material hydrocarbon, it is necessary to provide a desulfurization step before carrying out the steam reforming reaction. It has a complicated process.

  On the other hand, a method for producing hydrogen by a reforming reaction of methanol is also known. Although this reaction proceeds at a relatively low temperature of about 300 ° C., the copper / zinc catalyst used at that time is poor in durability, and further, since methanol as a raw material is synthesized from carbon monoxide and hydrogen, it has an environmental impact. This is not a hydrogen production method with reduced hydrogen.

  In recent years, it has been reported that hydrogen is generated by a steam reforming reaction of water-soluble hydrocarbons. Since this reaction uses plant-derived raw materials, the reaction proceeds under relatively mild conditions, and the reaction heat is not large, it is attracting attention as a method for producing hydrogen with reduced environmental burden. Wang et al. Have reported that hydrogen can be obtained in a high yield by performing a steam reforming reaction of acetic acid and hydroxyacetaldehyde at a temperature of 350 ° C. or higher in the presence of a nickel catalyst, but the catalytic activity decreases in a short time. (Non-Patent Document 1).

  In addition, the steam reforming reaction using water-soluble hydrocarbons such as glycerol as raw materials under low-temperature and high-pressure conditions where both water and hydrocarbons exist in the liquid phase, or both water and hydrocarbons exist in the gas phase. It is reported that the process proceeds under high temperature and low pressure conditions (Patent Document 1, Non-Patent Document 2).

As an example of a reaction under high temperature and low pressure conditions in which both water and hydrocarbon are present in the gas phase, a reforming reaction using sorbitol in the presence of a 1% by mass Rh / SiO ₂ catalyst is performed at 425 ° C. and 1 atm. It can be mentioned that hydrogen and carbon dioxide can be obtained in a high yield. However, if hydrogen is not added to the reaction system, there is a problem that the activity deterioration of the catalyst becomes extremely fast.

Examples of the reaction under low temperature and high pressure conditions in which both water and hydrocarbon are present in the liquid phase include a reaction using glucose, sorbitol, glycerol or ethylene glycol in the presence of a Pt / Al ₂ O ₃ catalyst. The reaction pressures at reaction temperatures of 225 ° C. and 265 ° C. are 27 atm and 54 atm, respectively. The reaction at high pressure is not desirable because of loss of compression energy and high equipment costs.

JP 2005-510437 Gazette

Appl. Catal. A, 1996, 143, 245-270. Nature, 2002, 418, 964-967.

  An object of the present invention is to provide a method for producing hydrogen with excellent energy efficiency, in which the reaction proceeds under low temperature and low pressure conditions, and without adding hydrogen, the catalyst has a long life.

As a result of intensive investigations to achieve the above object, the present inventors have found that water present in the gas phase and water solution present in the liquid phase and having at least two carbon atoms and at least two oxygen-carbon bonds. As a result of the steam reforming reaction of water-soluble hydrocarbons that react with reactive hydrocarbons, hydrogen was obtained with high efficiency and the catalyst deterioration rate was suppressed, and the present invention was completed.
That is, this invention is the method shown below.

[1] A feature of reacting water present in a gas phase with a water-soluble hydrocarbon having at least two carbon atoms and at least two oxygen-carbon bonds in the presence of a metal-containing catalyst. To produce hydrogen.
[2] The method for producing hydrogen according to the above [1], wherein the water-soluble hydrocarbon is a compound having 2 to 12 carbon atoms.

[3] The method for producing hydrogen according to the above [1], wherein the water-soluble hydrocarbon is glycerol, glyceraldehyde, glucose, sorbitol or sucrose.
[4] The method for producing hydrogen according to the above [1], wherein the carbon of the water-soluble hydrocarbon is glycerol.
[5] The method for producing hydrogen according to [1], wherein the reaction temperature is 100 ° C. or higher and 600 ° C. or lower.
[6] The method for producing hydrogen as described in [1] above, wherein the reaction temperature is from 100 ° C. to 400 ° C.
[7] The method for producing hydrogen as described in [1] above, wherein the reaction temperature is 150 ° C. or higher and 300 ° C. or lower.

[8] The metal-containing catalyst contains a metal of any of Group VIA, Group VIIA, Group VIII, Group IB, or Group IIB, an alloy of these metals, or a mixture of these metals. [1] The method for producing hydrogen according to [1].
[9] The method for producing hydrogen according to the above [8], wherein the metal-containing catalyst is from the group consisting of palladium, platinum, nickel, ruthenium, rhodium, cobalt, iron, zinc and rhenium.
[10] The metal-containing catalyst has at least one metal of Group VIA, Group VIIA, Group VIII, Group IB, and Group IIB, and the metal is at least one of Group IIIB, Group IVB, Group VB The method for producing hydrogen according to the above [8], wherein the method is alloyed or mixed with an element.
[11] The method for producing hydrogen as described in [10] above, wherein at least one element of Group IIIB, Group IVB, or Group VB is boron, tin, germanium, or bismuth.

[12] The method for producing hydrogen as described in [1] above, wherein the metal-containing catalyst is supported on a support of either oxide or activated carbon.
[13] The method for producing hydrogen according to [12], wherein the oxide is composed of at least one of silica, alumina, zirconia, zeolite, titania, ceria, and silica-alumina.
[14] The method for producing hydrogen as described in [12] above, wherein the metal content is 0.1 to 30% by mass with respect to the carrier.

  According to the present invention, the reaction proceeds under mild low-temperature and low-pressure conditions, and the life of the catalyst can be extended without adding hydrogen. It is possible to construct a hydrogen production process with low equipment costs and excellent energy efficiency.

  In the present invention, a water-soluble hydrocarbon having at least two carbon atoms and at least two oxygen-carbon bonds is used as a raw material. The oxygen-carbon bond is either a single bond or a double bond, and both may be mixed. As such a compound, a water-soluble hydrocarbon having 2 to 12 carbon atoms is preferable. Examples thereof include ethanediol, ethanedione, glycerol, glyceraldehyde, glucose, aldetetulose, aldopentose, aldohexose, hetotetrose, ketopentose, ketohexose, sucrose and other polysaccharides, and cellulose, fructose, starch and other polysaccharides. Is mentioned.

  Of these, glycerol, glyceraldehyde, glucose, sorbitol and sucrose are preferable, glycerol, glucose and sorbitol are more preferable, and glycerol is most preferable.

  In the present invention, the reaction is carried out at a pressure at which water is present in the gas phase and water-soluble hydrocarbons are present in the liquid phase. As reaction temperature, 100 degreeC or more and 600 degrees C or less are preferable, 100 degreeC or more and 400 degrees C or less are more preferable, 150 degreeC or more and 300 degrees C or less are especially preferable. When the reaction temperature is too high, the catalyst life is shortened due to coking and sintering of metal components. Moreover, it is not preferable that the reaction temperature is too high from the viewpoint of loss of heat energy. However, if the reaction temperature is too low, a sufficient reaction rate cannot be obtained.

  The reaction pressure is appropriately selected depending on the boiling point of the water-soluble hydrocarbon of the raw material, but it is preferable to carry out the reaction at a pressure as low as possible from the viewpoint of reducing the energy required for pressurization and further reducing the equipment cost. .

  The concentration of the water-soluble hydrocarbon is preferably 1 to 90% by mass, more preferably 5 to 50% by mass, particularly preferably 10 to 40% by mass, and most preferably 20 to 30% by mass. When the concentration of water-soluble hydrocarbons is low, the energy for heating water increases, and when the concentration of water-soluble hydrocarbons is high, the selectivity of hydrogen decreases and the amount of by-products of hydrocarbons such as methane increases. To do.

  In the present invention, a metal-containing catalyst is used as the catalyst. The catalyst contains at least one metal selected from Group VIA, Group VIIA, Group VIII, Group IB, and Group IIB. Two or more of these metals can be contained and used as an alloy or a mixture. Examples of metals of Group VIA, Group VIIA, Group VIII, Group IB, and Group IIB include palladium, platinum, nickel, ruthenium, rhodium, cobalt, iron, zinc, and rhenium. An element of group IIIB, group IVB, or group VB can be added to a metal of group VIA, group VIIA, group VIII, group IB, or group IIB, and used as an alloy or a mixture. Examples of suitable elements of Group IIB, Group IIIB, Group IVB, and Group VB include boron, tin, germanium, and bismuth.

  The metal-containing catalyst can be supported on oxide or activated carbon as required. In particular, it is preferable to use a catalyst carrier in order to impart heat resistance in a state where the metal component is highly dispersed. Examples of the oxide carrier include silica, alumina, zirconia, zeolite, titania, ceria, and silica-alumina, and these can be used alone or as a mixture.

  The method for supporting the metal-containing catalyst on the catalyst carrier is not particularly limited and can be prepared by a general method. Dissolve the raw material such as metal salt in the solvent, suspend the catalyst carrier, evaporate to dryness with heating, or volume fraction of the metal salt solution equal to the pore volume of the carrier. The impregnating Incipient Wetness method, a method in which metal ions are ion-exchanged at the acid point or base point of the catalyst carrier, and the like can be used. After the metal-containing catalyst is supported on the catalyst carrier, it is appropriately dried and calcined as necessary.

The activation of the catalyst may be carried out by passing hydrogen gas through a dried or calcined catalyst containing metal ions, or may be reduced with a raw material containing a hydroxyl group.
The content of the metal-containing catalyst with respect to the catalyst carrier is preferably 0.1 to 30% by mass, more preferably 0.3 to 20% by mass, and particularly preferably 0.5 to 10% by mass. Preferably, it is 0.5 to 5% by mass. When the content is too large, the catalyst activity per unit mass of the metal-containing catalyst is lowered, and the sintering of the catalyst tends to occur. Further, when the content is low, the catalyst activity per unit mass of the catalyst is lowered.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

<Example 1>
4.5 g of 5 mass% Pt / Al ₂ O ₃ catalyst (manufactured by N.E. Chemcat), meshed to a particle size of 250 μm to 500 μm, was charged into a SUS tubular reactor. The reactor was connected to a flow reactor, and the temperature was raised under a nitrogen flow. After the internal temperature of the reactor reached 225 ° C., the nitrogen flow was stopped, and a 10% by mass glycerol aqueous solution was passed through the reactor at a rate of 3.6 g / h to initiate the reaction. The reaction was performed under atmospheric pressure conditions. The boiling point of glycerol at 1 atmosphere is 290 ° C., and it is considered that glycerol is naturally present in the liquid phase at the reaction temperature of 225 ° C. and atmospheric pressure. The product gas and the reaction liquid were collected from the product after 5 hours from the start of the reaction using a gas-liquid separator and a gas sampler.
The product gas and the liquid phase part were quantified by an absolute calibration curve method using a gas chromatograph.

The hydrogen gas yield was defined as follows.
Hydrogen gas yield (%) = (moles of hydrogen produced / moles of hydrogen theoretically produced from glycerol fed) × 100

The theoretical reaction formula for synthesizing hydrogen from glycerol is shown below.
Glycerol _{+ 3H 2 O → 7H 2 +} 3CO 2

As a result, hydrocarbons remaining in the product liquid were not detected. The product gas was mainly hydrogen, carbon dioxide and methane, and the yield of hydrogen gas was 20 mol%. Even after 12 hours from the start of the reaction, no deterioration in the activity of the catalyst was observed.

  Hydrogen is useful for various applications such as raw materials such as ammonia, methanol, hydrogen peroxide, semiconductor manufacturing, metallurgy, etc., and is extremely useful as a next-generation clean energy source for fuel cells, hydrogen engine automobiles, etc. It is.

Claims (14)

  In the presence of a metal-containing catalyst, hydrogen present in the gas phase is reacted with a water-soluble hydrocarbon present in the liquid phase and having at least two carbon atoms and at least two oxygen-carbon bonds. Production method.   The method for producing hydrogen according to claim 1, wherein the water-soluble hydrocarbon has 2 to 12 carbon atoms.   The method for producing hydrogen according to claim 1, wherein the water-soluble hydrocarbon is glycerol, glyceraldehyde, glucose, sorbitol, or sucrose.   The method for producing hydrogen according to claim 1, wherein the water-soluble hydrocarbon is glycerol.   The method for producing hydrogen according to claim 1, wherein the reaction temperature is 100 ° C or higher and 600 ° C or lower.   The method for producing hydrogen according to claim 1, wherein the reaction temperature is 100 ° C. or higher and 400 ° C. or lower.   The method for producing hydrogen according to claim 1, wherein the reaction temperature is 150 ° C or higher and 300 ° C or lower.   2. The hydrogen production according to claim 1, wherein the metal-containing catalyst comprises a metal of Group VIA, Group VIIA, Group VIII, Group IB, Group IIB, an alloy of these metals, or a mixture of these metals. Method.   9. The method for producing hydrogen according to claim 8, wherein the metal is palladium, platinum, nickel, ruthenium, rhodium, cobalt, iron, zinc, or rhenium.   The metal-containing catalyst has at least one metal of Group VIA, Group VIIA, Group VIII, Group IB, and Group IIB, and the metal is alloyed with at least one element of Group IIIB, Group IVB, Group VB The method for producing hydrogen according to claim 8, wherein the method is mixed or mixed.   11. The method for producing hydrogen according to claim 10, wherein at least one element of the group IIIB, group IVB, or group VB is boron, tin, germanium, or bismuth.   2. The method for producing hydrogen according to claim 1, wherein the metal-containing catalyst is supported on a support of either oxide or activated carbon.   The method for producing hydrogen according to claim 12, wherein the oxide is composed of at least one of silica, alumina, zirconia, zeolite, titania, ceria, and silica-alumina.   The method for producing hydrogen according to claim 12, wherein the amount of the metal-containing catalyst is 0.1 to 30% by mass with respect to the support.