JP2013212477A - Catalyst and method for producing hydrogen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst for producing hydrogen, which is more inexpensive than a noble metal and has sulfur resistance and to provide a method for producing hydrogen by using the catalyst for producing hydrogen.SOLUTION: A catalyst for producing hydrogen contains barium titanate or strontium titanate. It does not matter if Fe and/or Sr are deposited on a barium titanate particle or a strontium titanate particle. Hydrogen is produced by reacting sulfur-containing fuel with steam by using the catalyst for producing hydrogen. The catalyst for producing hydrogen is not poisoned by a sulfur compound but allows hydrogen production efficiency, when the sulfur compound exists in the fuel, to be made higher than that when the fuel does not exist therein. As a result, hydrogen can efficiently be produced from the sulfur compound-containing fuel.

Description

  The present invention relates to a hydrogen production catalyst for producing hydrogen by reacting a fuel gas composed of lower hydrocarbons such as city gas and LPG with water vapor, and a hydrogen production method using the hydrogen production catalyst.

  In recent years, it has been known that a large amount of low-quality natural gas (sub-quality natural gas) such as some shale gas containing a large amount of impurities such as hydrogen sulfide and carbon dioxide exists all over the world. . However, despite the low cost, refining (especially desulfurization) is difficult and expensive, so that it is not effectively used. In particular, in order to produce hydrogen from these low-quality natural gases, sulfur poisoning by hydrogen sulfide as a reforming catalyst becomes a big problem. If it is possible to produce hydrogen from the above-mentioned low-quality natural gas without sulfur poisoning, it will be possible to produce hydrogen at a low cost, which can greatly contribute to the future hydrogen society.

  Patent Documents 1 and 2 describe the use of a noble metal made of Ir, Pt, or Pd that is resistant to sulfur.

Patent Documents 3 and 4 describe that the tar content in the biomass gasification gas is decomposed with a BaTiO ₃ catalyst, but does not describe that lower hydrocarbons are decomposed with BaTiO ₃ .

Special table 2007-532305 Special table 2009-543750 JP 2010-229271 A JP2011-245426

  The noble metal catalyst is expensive and may increase the cost of hydrogen production.

  An object of the present invention is to provide a hydrogen production catalyst having sulfur resistance that is cheaper than a noble metal and a hydrogen production method using the hydrogen production catalyst.

  The hydrogen production catalyst according to the first aspect of the present invention is a catalyst for producing hydrogen by reacting a fuel containing sulfur and water vapor, characterized by containing barium titanate.

  The hydrogen production catalyst of the second invention is a catalyst for producing hydrogen by reacting a fuel containing sulfur and water vapor, characterized in that it contains strontium titanate.

  Each hydrogen production catalyst is preferably granular.

  Granular barium titanate may carry Fe and / or Sr.

  Granular strontium titanate may carry Fe and / or Ba.

  In the hydrogen production method of the present invention, hydrogen is produced by reacting a fuel containing sulfur with water vapor in the presence of the hydrogen production catalyst of the present invention.

The hydrogen production catalyst of the present invention is suitably used as a catalyst for reforming a fuel containing sulfur, for example, a lower hydrocarbon containing a sulfur compound and steam. According to the results of the inventor's research, the catalyst of the present invention not only is not poisoned by sulfur compounds, but when sulfur compounds are present in lower hydrocarbons, it produces more hydrogen than lower hydrocarbons that do not contain sulfur compounds. It was observed that efficiency was improved. The present invention is based on such knowledge. According to the present invention, hydrogen can be efficiently produced from a fuel containing sulfur, for example, a lower hydrocarbon containing a sulfur compound.
In particular, the present invention can efficiently obtain hydrogen without desulfurization treatment from low-quality natural gas (such as some shale gas) having a high sulfur concentration, LPG, coal reformed gas, or the like.

It is a graph which shows a hydrogen production experiment result. It is a graph which shows a hydrogen production experiment result. It is a graph which shows a hydrogen production experiment result. It is a graph which shows a hydrogen production experiment result. It is a graph which shows a hydrogen production experiment result. It is a graph which shows a hydrogen production experiment result. It is a TEM photograph of barium titanate particles. 2 is an X-ray diffraction chart of barium titanate.

  Hereinafter, the present invention will be described in more detail.

[Catalyst for barium titanate-based hydrogen production]
The hydrogen production catalyst of the first invention contains barium titanate. As this barium titanate, what is represented by (BaO) _X · TiO ₂ (0.9 ≦ X ≦ 1.1) is preferable. A part of Ba of barium titanate may be substituted with at least one other element such as La, Sr, and Ca. Moreover, a part of Ti of barium titanate may be substituted with at least one of other metal elements such as Cr, Mn, Fe, Co, Ni, Al, Zr, Nb, Sn, and Ce.

  The barium titanate is preferably composed of particles having an average particle diameter of 50 to 200 nm, particularly about 30 to 50 nm (measurement method is TEM method), but is not limited thereto.

  In order to produce barium titanate, titanium oxide and / or a titanium compound that becomes titanium oxide by firing (for example, carbonate, hydroxide, etc.) and barium oxide and / or a barium compound that becomes barium oxide by firing are produced. (For example, carbonate, hydroxide, etc.) may be mixed, fired, and pulverized.

  The barium titanate particles may carry Fe and / or Sr. In this case, Fe is preferably iron oxide, and Sr is preferably SrO. In order to support Fe and / or Sr, iron oxide, SrO, Fe compound that becomes iron oxide by firing (for example, iron carbonate, iron nitrate, iron chloride, iron sulfide, etc.), and Sr compound that becomes SrO by firing (for example, carbonic acid) Strontium, strontium nitrate, strontium chloride, etc.) are mixed with barium titanate particles and preferably fired at 600 to 750 ° C., but not limited thereto.

  In addition, a solution in which Fe salt and / or Sr salt is dissolved in a solvent such as water is attached to barium titanate particles, dried, and then fired under the same firing conditions as described above to carry Fe and / or Sr. May be. Examples of suitable water-soluble Fe salts include iron nitrate and iron chloride, and examples of Sr salts include strontium nitrate and strontium chloride.

  The amount of Fe and / or Sr supported on the barium titanate particles is preferably 10 wt% or less, for example, about 0.5 to 5 wt% of the barium titanate particles as the metal weight of Fe and / or Sr.

[Strontium titanate-based hydrogen production catalyst]
The hydrogen production catalyst of the second invention contains strontium titanate. The strontium titanate is preferably represented by (SrO) _X · TiO ₂ (0.9 ≦ X ≦ 1.1). A part of Sr in strontium titanate may be substituted with at least one other element such as La, Ba, and Ca. Further, a part of Ti of strontium titanate may be substituted with at least one of other metal elements such as Cr, Mn, Fe, Co, Ni, Al, Zr, Nb, Sn, and Ce.

  The strontium titanate is preferably composed of particles having an average particle diameter of about 50 to 200 nm, but is not limited thereto.

  In order to produce strontium titanate, titanium oxide and / or a titanium compound that becomes titanium oxide by firing (for example, carbonate, hydroxide, etc.) and strontium oxide and / or a strontium compound that becomes strontium oxide by firing (For example, carbonate, hydroxide, etc.) may be mixed, baked, and pulverized.

  The strontium titanate particles may carry Fe and / or Ba. Fe in this case is preferably iron oxide, and Ba is preferably BaO. In order to carry Fe and / or Ba, iron oxide, BaO, an Fe compound that becomes iron oxide by firing (for example, iron carbonate, iron nitrate, iron chloride, iron sulfide, etc.), and a Ba compound that becomes BaO by firing (for example, carbonic acid). Barium, barium nitrate, and barium chloride) are preferably mixed with strontium titanate particles and fired at 600 to 750 ° C., but are not limited thereto.

  Further, a solution in which Fe salt and / or Ba salt is dissolved in a solvent such as water is attached to strontium titanate particles, dried, and then fired under the same firing conditions as described above to carry Fe and / or Ba. May be. Examples of suitable water-soluble Fe salts include iron nitrate and iron chloride, and examples of the Ba salt include barium nitrate and barium chloride.

  The amount of Fe and / or Ba supported on the strontium titanate particles is preferably 10 wt% or less, for example, about 0.5 to 5 wt% of the strontium titanate particles as the metal weight of Fe and / or Ba.

  The above barium titanate particles and strontium titanate particles may be used alone or in combination. Barium titanate particles and / or strontium titanate particles may be granulated or formed by various methods. The granulated particle shape may be any shape such as a spherical shape, a pellet shape, a ring shape, or a rod shape, and may be a uniform shape or a non-uniform shape.

  The shape of the molded body is also arbitrary such as a honeycomb shape. Alternatively, a sponge-like porous molded body having communication holes may be used.

[Fuel containing sulfur]
Examples of the fuel containing sulfur include low-quality natural gas (such as some shale gas) having a high sulfur concentration, LPG, coal reformed gas, and the like, and lower hydrocarbon gas containing a sulfur compound. Examples of the lower hydrocarbon gas include one or more of lower hydrocarbons having 4 or less carbon atoms such as methane, ethane, ethylene, propane, and butane, or natural gas, city gas, LP gas, and the like containing these. Thus, those containing a sulfur compound are preferably used. Examples of sulfur compounds include sulfides such as dimethyl sulfide, ethyl methyl sulfide, and diethyl sulfide, thiophenes such as tetrahydrothiophene, mercaptans such as butyl mercaptan, isopropyl mercaptan, normal propyl mercaptan, amyl mercaptan, heptyl mercaptan, methyl mercaptan, and ethyl mercaptan. H ₂ S contained in a large amount in odorants such as odors and low-quality natural gas.

[Method for producing hydrogen]
In order to produce hydrogen using the catalyst, fuel gas and water vapor may be supplied and reacted in a reactor having the catalyst.

The gas flowing out from the reactor contains H ₂ , CO, CO ₂ , unreacted H ₂ O, lower hydrocarbons, and the like. This reaction gas is introduced into a high-temperature shift converter, and CO and water vapor are reacted to convert into H ₂ and CO ₂ . Thereafter, hydrogen is separated and removed by a hydrogen separator through a heat exchanger, a water separation tank, and the like. As the hydrogen separator, various devices such as those using a separation membrane or an adsorbent can be used.

[Example 1 (BaTiO ₃ catalyst)]
A commercially available product for producing a ceramic capacitor was used as BaTiO ₃ . The BaTiO _{3 had} a BaO / TiO ₂ ratio of 0.99 / 1.01, and a BET specific surface area of 20 to 22 m ² / g. The particle size of this BaTiO ₃ by TEM method was 30 to 50 nm.

<Hydrogen production experiment 1>
A quartz tube having a diameter of 10 mm and a length of 500 mm was passed through an electric furnace, and a catalyst bed made of 3 g of the catalyst was formed at the center in the longitudinal direction of the quartz tube. The quartz tube is heated so that the temperature of the central portion is 700, 750, 800, or 850 ° C., and the source gas having the following composition is set to 250 mL / min (SV = 5000 / Hr) at atmospheric pressure in the quartz tube. The methane reforming reaction was carried out.
CH ₄ 20% by volume
20% by volume of H ₂ O
H ₂ S 0 ppm or 500 ppm
N ₂ balance

The product gas composition was analyzed and the hydrogen yield was measured. The result is shown in FIG. The hydrogen yield was calculated by [H ₂ ] _out / 3 [CH ₄ ] _in × 100 (%). “[H ₂ ] _out ” represents the H ₂ molar concentration in the product gas (quartz tube outflow gas), and “[CH ₄ ] _in ” represents the CH ₄ molar concentration in the source gas (quartz tube inflow gas). Represent.

As shown in FIG. 1, at any reaction temperature of 700 to 850 ° C., the case where H ₂ S containing H ₂ S = 500 ppm is higher than the case where H ₂ S does not contain H ₂ S = 0 ppm. Hydrogen yield is high.

<Hydrogen production experiment 2>
In the experiment 1, the reaction temperature was 650 ° C. And, it was the same except that the raw material gas was H ₂ S = 0 ppm for ₂ hours from the start of the experiment, and the raw material gas was H ₂ S = 500 ppm after the passage of ₂ hours. The change over time in the hydrogen yield is shown in FIG. As shown in FIG. 6, by adding H ₂ S, the hydrogen yield is increased about twice or more.

[Example 2 (Fe · Sr / BaTiO ₃ catalyst)]
<Catalyst synthesis>
The same commercially available product as used in Example 1 was used as BaTiO ₃ . 100 parts by weight of BaTiO _3, 1 part by weight of reagent-grade Fe ₂ O _{3 and} 1 part by weight of SrCO ₃ were mixed in a mortar for 20 hours, and then calcined at 750 ° C. in an air atmosphere for 1 hour.

The obtained Fe and Sr-supported BaTiO ₃ (Fe · Sr / BaTiO ₃ ) had a particle size of 30 to 50 nm by the TEM method (FIG. 7). As a result of energy dispersive X-ray spectroscopy (EDX), it was confirmed that Fe and Sr were present on the surface of BaTiO ₃ particles. According to X-ray diffraction, the crystal structure was a perogskite structure, but a small amount of BaCO ₃ was observed (FIG. 8). The BET specific surface area was 21 m ² / g.

<Hydrogen production experiment (methane reforming)>
A methane reforming reaction was carried out in the same manner as in Example 1 except that this Fe · Sr / BaTiO ₃ was used as a catalyst. The measurement result of the hydrogen yield is shown in FIG.

As Figure 2, 700-850 at any reaction temperature ° C., yield it is hydrogen in the case of raw material gas containing _{H 2} S than in the raw material gas _H 2 S = 0 ppm free of _{H 2} S The rate is high.

<Hydrogen production experiment (ethane reforming)>
Ethane was reformed in the same manner as above except that ethane (C ₂ H ₆ ) was supplied at the same volume flow rate instead of methane (CH ₄ ) in the raw material gas. The measurement results of the hydrogen yield are shown in FIG. In addition, the hydrogen yield in this case was calculated by [H ₂ ] _out / 5 [C ₂ H ₆ ] _in × 100 (%).

As Figure 3, 700-850 at any reaction temperature ° C., yield it is hydrogen in the case of raw material gas containing _{H 2} S than in the raw material gas _H 2 S = 0 ppm free of _{H 2} S The rate is high.

[Example 3 (SrTiO ₃ catalyst)]
Hydrogen was produced in the same manner as in Example 1 except that commercially available SrTiO ₃ was used instead of BaTiO ₃ , and the yield is shown in FIG.

Figure as 4, in any of the reaction temperature of 700-850 ° C., yield it is hydrogen in the case of raw material gas containing _{H 2} S than in the raw material gas _H 2 S = 0 ppm free of _{H 2} S The rate is high.

[Example 4 (Fe · Ba / SrTiO ₃ catalyst)]
<Catalyst synthesis>
The same commercially available SrTiO ₃ as that used in Example 3 was used. 100 parts by weight of SrTiO _{3 is} mixed with 1 part by weight of reagent-grade Fe ₂ O _{3 and} 1 part by weight of BaCO ₃ in a mortar for 20 hours, and then calcined at 750 ° C. in an air atmosphere for 1 hour to obtain Fe and Ba-supported SrTiO ₃ was produced.

As a result of energy dispersive X-ray spectrometry (EDX), it was confirmed that Fe and Ba were present on the surface of SrTiO ₃ particles. According to X-ray diffraction, the crystal structure was a perogskite structure, but a small amount of SrCO ₃ was observed.

<Hydrogen production experiment>
Hydrogen was produced in the same manner as in Example 1 except that this Fe · Ba / SrTiO ₃ was used as a catalyst, and the yield is shown in FIG.

As Figure 5, 700-850 at any reaction temperature ° C., towards hydrogen in the case of the raw material gas containing _{H 2} S than in the raw material gas _H 2 S = 0 ppm free of _{H 2} S yield The rate is high.

Claims (9)

  A catalyst for producing hydrogen by reacting a fuel containing sulfur with water vapor to produce hydrogen, comprising barium titanate.   The catalyst for hydrogen production according to claim 1, wherein barium titanate is particles.   3. The hydrogen production catalyst according to claim 2, wherein the barium titanate particles carry Fe and / or Sr.   A catalyst for producing hydrogen by reacting a fuel containing sulfur with water vapor to produce hydrogen, comprising strontium titanate.   The catalyst for hydrogen production according to claim 4, wherein strontium titanate is particles.   6. The hydrogen production catalyst according to claim 5, wherein the strontium titanate particles carry Fe and / or Ba.   A hydrogen production method comprising a step of reacting a fuel containing sulfur and water vapor in the presence of the hydrogen production catalyst according to any one of claims 1 to 6.   8. The method for producing hydrogen according to claim 7, wherein the fuel containing sulfur is natural gas, LPG, or coal reformed gas.   8. The method for producing hydrogen according to claim 7, wherein the fuel containing sulfur is a lower hydrocarbon gas containing a sulfur compound.

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