WO2013022189A1 - Method of producing hydrogen by splitting water on solid acid materials - Google Patents

Method of producing hydrogen by splitting water on solid acid materials Download PDF

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WO2013022189A1
WO2013022189A1 PCT/KR2012/005271 KR2012005271W WO2013022189A1 WO 2013022189 A1 WO2013022189 A1 WO 2013022189A1 KR 2012005271 W KR2012005271 W KR 2012005271W WO 2013022189 A1 WO2013022189 A1 WO 2013022189A1
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solid acid
water
metal
reactor
mixture
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PCT/KR2012/005271
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French (fr)
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Young Sang Cho
Jae Ik Kim
Ju Hee Kim
In Hwan Oh
Kyung-Ho Shin
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Korea Institute Of Science And Technology
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Publication of WO2013022189A1 publication Critical patent/WO2013022189A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
    • C01B3/061—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents by reaction of metal oxides with water
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J7/00—Apparatus for generating gases
    • B01J7/02—Apparatus for generating gases by wet methods
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
    • C01B3/10—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents by reaction of water vapour with metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00002—Chemical plants
    • B01J2219/00004—Scale aspects
    • B01J2219/00006—Large-scale industrial plants
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Definitions

  • the present invention relates to a method of producing hydrogen by splitting water.
  • Conventional methods of producing hydrogen using water as a raw material include electrolytic methods, which use electrical energy, and thermal decomposition methods which use thermal energy.
  • the electrolytic methods should employ high-grade energy (electricity) and have low water splitting efficiency.
  • the thermal decomposition methods may be methods which use primary fuel or solar cell and include a one-step direct decomposition method, and a two-step indirect decomposition method of producing hydrogen by thermally decomposing a metal oxide into a metal and oxygen and then allowing the metal to react with water.
  • a reaction temperature of at least 2500 K is required
  • the temperature for decomposing a metal oxide is required to be at least 1500 K.
  • the thermal decomposition methods have problems associated with the material of a reaction system due to high reaction temperatures, in addition to a problem in that thermal efficiency is reduced. Due to such problems, the thermal decomposition methods are not commercially used.
  • Another object of the present invention is to solve the above-described problems while improving the efficiency of hydrogen production. Another object of the present invention is to enable hydrogen to be commercially produced by thermal splitting of water.
  • a method of producing hydrogen by thermal splitting of water comprising the steps of: (a) adding water or steam to a solid acid or a solid acid mixture of the solid acid with at least one material selected from a metal and an electrolyte so as to adsorb water on the solid acid or the solid acid mixture; (b) introducing the water-adsorbed solid acid or solid acid mixture into a reactor made of a heat-resistant and pressure-resistant material, and splitting the water on the introduced solid acid or solid acid mixture to produce hydrogen; and (c) discharging the solid acid or solid acid mixture, used in the splitting of the water, from the reactor.
  • the production method may comprise repeating steps (a) to (c).
  • the production method may comprise cooling the solid acid or solid acid mixture discharged in step (c) to a temperature of 273 ⁇ 373 K, adding water or steam thereto to adsorb water on the solid acid or the solid acid mixture, and then repeating steps (b) and (c).
  • the production method may further comprise a step of discharging a hydrogen-containing product from the reactor and measuring the content of hydrogen in the hydrogen-containing product by gas chromatography.
  • step (b) of the production method may comprise maintaining the inside of the reactor in step (b) at a temperature between 500 K to 1500 K and a pressure between 0.5 atm and 100 atm.
  • step (b) may further comprise, before step (b), a step of injecting carrier gas into the reactor, and after step (b), a step of discharging a gas product from the reactor in a mixture with the carrier gas.
  • the carrier gas may be selected from the group consisting of hydrogen, nitrogen, argon, carbon dioxide, and steam.
  • the solid acid or solid acid mixture used in the splitting of the water may be discharged from the reactor at a specific rate from 5 minutes to 5 hours after introduction thereof.
  • the solid acid may be any one or a mixture of two or more selected from the group consisting of basalt, granite, limestone, sandstone, kaolinite, attapulgite, bentonite, montmorillonite, zinc oxide (ZnO), aluminum oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), cesium oxide (CeO 2 ), vanadium oxide (V 2 O 5 ), silicon oxide (SiO 2 ), chromium oxide (Cr 2 O 3 ), calcium sulfate (CaSO 4 ), manganese sulfate (MnSO 4 ), nickel sulfate (NiSO 4 ), copper sulfate (CuSO 4 ), cobalt sulfate (CoSO 4 ), cadmium sulfate (CdSO 4 ), magnesium sulfate (MgSO 4 ), iron (II) sulfate (FeSO 4 ), aluminum sulfate (Al)
  • the metal may be any one or a mixture of two or more selected from the group consisting of aluminum, zinc, iron, cobalt, manganese, chromium and nickel.
  • the electrolyte may be any one or a mixture of two or more selected from the group consisting of sodium chloride (NaCl), potassium chloride (KCl), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), sodium sulfate (Na 2 SO 4 ), potassium sulfate (K 2 SO 4 ), lithium carbonate (Li 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium dihydrogen phosphate (NaH 2 PO 4 ), sodium monohydrogen phosphate (Na 2 HPO 4 ), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium chloride (CaCl 2 ), magnesium chloride (MgCl 2 ), calcium nitrate (Ca(NO 3 ) 2 ), magnesium nitrate (Mg(NO 3 ) 2 ), calcium sulfate (CaSO 4 ), magnesium sulfate (Mg
  • each of the solid acid, the metal and the electrolyte may be in the form of powder and may have a particle size of 20-500 mesh.
  • the solid acid mixture of the solid acid with the metal may comprise metal particles deposited in the pores of solid acid powder, in which the metal particles have a diameter of 10 ⁇ m or less.
  • the solid acid mixture of the solid acid with the metal may comprise either metal powder coated on the surface of solid acid powder or solid acid powder coated on the surface of metal powder, in which the metal powder or the solid acid powder may be coated to a thickness more than 10 nm and 10 ⁇ m or less.
  • the solid acid mixture of the solid acid with the metal may comprise 60 wt% or more of the solid acid and 40 wt% or less of the metal.
  • the solid acid mixture of the solid acid with the metal and the electrolyte may comprise electrolyte particles deposited in the pores of a mixture of solid acid and metal, in which the electrolyte particles may have a diameter of 10 ⁇ m or less.
  • the solid acid mixture of the solid acid with the metal and the electrolyte may comprise either electrolyte powder coated on the surfaces of solid acid and metal powders or solid acid powder coated on the surface of metal and electrolyte powders, in which the electrolyte powder or the solid acid film powder may be coated to a thickness more than 10 nm and 10 ⁇ m or less.
  • the solid acid mixture of the solid acid with the metal and the electrolyte may comprise 70 wt% or more of the solid acid/metal mixture and 30 wt% or less of the metal.
  • the reactor may be made of SUS (stainless steel), carbon steel, or a mixture thereof, which has an iron content of 70% or more.
  • a solid acid adsorbed with a maximum amount of water is continuously introduced into a reactor which is maintained at a specific temperature and a specific pressure, whereby continuous splitting of water in the reactor is possible, thereby increasing the production of hydrogen. Accordingly, the economic efficiency of producing hydrogen by thermal splitting of water can be increased, and thus the production of hydrogen by thermal splitting of water can be commercialized.
  • FIG. 1 is a schematic diagram showing an apparatus for testing of water splitting reactions used in the test examples of the present invention.
  • FIG. 2 is a schematic diagram showing a testing apparatus used in Comparative Example 2.
  • 70 liquid flow controller
  • 80 gas flow controller
  • 150 sampling container
  • 160 temperature controller
  • a method of producing hydrogen by splitting of water according to the present invention is as follows. Step (a): a solid acid, a metal/solid acid mixture, an electrolyte/solid acid mixture or a metal/electrolyte/solid acid mixture is placed in a water adsorbing container 12, and a desired amount of water or steam is introduced into the water adsorbing container 12 so that liquid-state water is adsorbed on the solid acid or the solid acid mixture. Step (b): the solid acid or solid acid mixture adsorbed with water is continuously introduced into a reactor 6 made of a heat-resistant and pressure-resistant material.
  • the solid acid or solid acid mixture used in the water splitting reaction may be discharged from the reactor through a solid acid discharge controller 8 at a specific rate from 5 minutes to 5 hours after introduction thereof.
  • steps (a) to (c) may be repeatedly carried out, whereby hydrogen can be continuously produced in the reactor.
  • the production method of the present invention may comprise cooling the solid acid or solid acid mixture discharged in step (c) to a temperature of 273 ⁇ 373 K, adding water or steam thereto to adsorb water, and then repeating steps (b) and (c) to introduce the solid acid or the solid acid mixture again into the reactor.
  • the solid acid maintained in the reactor for 5 minutes to 5 hours is discharged from the reactor and cooled by a solid acid cooler 9.
  • the cooled solid acid is adsorbed again with water in the water adsorbing container 12 and introduced again into the reactor. These processes are repeated, whereby hydrogen is continuously produced in the reactor.
  • the production method of the present invention may further comprise a step of discharging a hydrogen gas product from the reactor and measuring the hydrogen content of the discharged hydrogen gas product by a gas chromatography device 16.
  • the method of the present invention may further comprise, before step (b), a step of injecting carrier gas into the reactor, and after step (b), a step of discharging a gas product from the reactor in a mixture with the carrier gas.
  • the carrier gas can be introduced from a gas supply container 3 through a gas flow meter 5 into the reactor 6.
  • the carrier gas can be discharged from the reactor 6 through a pressure controller 15.
  • hydrogen, oxygen and steam which are produced in the reactor, can be smoothly moved to the outside of the reactor.
  • the carrier gas may be selected from the group consisting of hydrogen, nitrogen, argon, carbon dioxide, and steam.
  • Reaction scheme 1 schematically shows a water splitting reaction on the solid acid.
  • reaction scheme 1 water is adsorbed on the Lewis acid site of the solid acid by a coordinate bond to form a Bronsted acid site which then forms a hydrogen bond with the oxygen of the solid acid, whereby water is adsorbed on the solid acid by the two types of bonds (coordinate bond and hydrogen bond).
  • the solid acid adsorbed with water by the two bonds is heated, electrons are exchanged through the two bonds while the water adsorbed on the solid acid is electrolyzed into hydrogen and a hydroxyl radical.
  • the efficiency of water splitting can be maximized by adsorbing liquid-state liquid on the solid acid.
  • the solid acid that is used in the present invention may be any one or a mixture of two or more selected from the group consisting of basalt, granite, limestone, sandstone, kaolinite, attapulgite, bentonite, montmorillonite, zinc oxide (ZnO), aluminum oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), cesium oxide (CeO 2 ), vanadium oxide (V 2 O 5 ), silicon oxide (SiO 2 ), chromium oxide (Cr 2 O 3 ), calcium sulfate (CaSO 4 ), manganese sulfate (MnSO 4 ), nickel sulfate (NiSO 4 ), copper sulfate (CuSO 4 ), cobalt sulfate (CoSO 4 ), cadmium sulfate (CdSO 4 ), magnesium sulfate (MgSO 4 ), iron (II) oxide (FeSO 4 ), aluminum sulfate (Al 2 (SO 4
  • the solid acid may be used in a mixture with a metal.
  • the metal can increase the efficiency of water splitting at a reaction temperature of 1500 K or lower. This is because electron transfer is more activated by the metal in a process in which the surface electrons of the solid acid move to the hydrogen ions of water.
  • the metal that is used in the present invention may be any one or a mixture or alloy of two or more selected from the group consisting of aluminum, zinc, iron, cobalt, manganese, chromium and nickel.
  • Each of the solid acid and the metal which are used in the present invention, may be in the form of powder and may have a particle size of 20-500 mesh.
  • the particle sizes of the solid acid powder and the metal power become smaller, the surface areas thereof become larger.
  • the efficiency of the water splitting reaction becomes higher.
  • the sizes of the particles are larger than 500 mesh, the particles can be lost from the reactor by the flow of the carrier gas, and if the particle size is smaller than 20 mesh, the reaction efficiency can greatly decrease.
  • the sizes of the solid acid power and the metal powder are preferably 20-500 mesh in view of reactivity and process maintenance.
  • the metal/solid acid mixture which is used in the present invention may be composed of metal particles deposited in the pores of the solid acid powder.
  • the diameter of the metal particles is 10 ⁇ m or less, because the reaction efficiency decreases as the size of the metal particles increases.
  • the metal/solid acid mixture that is used in the present invention may comprise either metal powder coated on the surface of solid acid powder or solid acid powder coated on the surface of metal powder, in which the metal powder or the solid acid powder may be coated to a thickness more than 10 nm and 10 ⁇ m or less. When the metal powder or the solid acid powder is coated to a thickness more than 10 nm and 10 ⁇ m or less, good reaction efficiency will be ensured.
  • the metal/solid acid mixture that is used in the present invention may comprise 60 wt% or more of the solid acid and 40 wt% or less of the metal. If the metal powder is contained in an amount of more than 40 wt%, a reaction between the metal powder and water will predominantly occur, and thus splitting of water by the solid acid will significantly decrease. Accordingly, more preferably, the content of the metal powder is maintained at 20 wt% or less, and in this case, the best efficiency can be obtained.
  • the solid acid/metal mixture may be used in a mixture with an electrolyte, and in this case, the efficiency of water splitting can be increased by the electrolyte. This is because electron transfer is more activated by the electrolyte in a process in which the surface electrons of the solid acid move to the hydrogen ions of water.
  • the electrolyte that is used in the present invention may be any one or a mixture of two or more selected from the group consisting of sodium chloride (NaCl), potassium chloride (KCl), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), sodium sulfate (Na 2 SO 4 ), potassium sulfate (K 2 SO 4 ), lithium carbonate (Li 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium dihydrogen phosphate (NaH 2 PO 4 ), sodium monohydrogen phosphate (Na 2 HPO 4 ), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium chloride (CaCl 2 ), magnesium chloride (MgCl 2 ), calcium nitrate (Ca(NO 3 ) 2 ), magnesium nitrate (Mg(NO 3 ) 2 ), calcium phosphate (CaSO 4 ), magnesium sulfate (MgSO 4
  • Each of the solid acid, the metal and the electrolyte which are used in the present invention may be in the form of powder and may have a particle size of 20-500 mesh.
  • the particle sizes of the solid acid powder, the metal powder and the electrolyte powder become smaller, the surface areas thereof become larger.
  • the efficiency of the water splitting reaction becomes higher.
  • the size of the particles is larger than 500 mesh, the particles can be lost from the reactor can be lost from the reactor by the flow of the carrier gas, and if the particle size is smaller than 20 mesh, the efficiency of the water splitting reaction can greatly decrease. Therefore, the sizes of the solid acid powder and the metal powder are preferably 20-500 mesh in view of reactivity and process maintenance.
  • the metal/electrolyte/solid acid mixture that is used in the present invention may comprise electrolyte particles deposited in the pores of a solid acid/metal mixture.
  • the electrolyte particles deposited in the pores of the solid acid and metal powders preferably have a diameter of 10 ⁇ m, because the efficiency of the water splitting reaction increases as the size of the electrolyte particles decreases.
  • the metal/electrolyte/solid acid mixture that is used in the present invention may comprise either electrolyte powder coated on the surfaces of solid acid and metal powders or solid acid powder coated on the surfaces of metal and electrolyte powders, in which the electrolyte powder or the solid acid powder may be coated to a thickness more than 10 nm and 10 ⁇ m or less.
  • the electrolyte powder or the solid acid powder is coated to a thickness more than 10 nm and 10 ⁇ m or less, good reaction efficiency will be ensured.
  • the metal/electrolyte/solid acid mixture that is used in the present invention may comprise 70 wt% or more of the solid acid/metal mixture and 30 wt% or less of the electrolyte. If the electrolyte powder is contained in an amount of more than 30 wt%, the electrolyte will significantly interfere with the movement of electrons, and thus the efficiency of water splitting by the solid acid will significantly decrease. Thus, the content of the electrolyte powder is more preferably maintained at 15 wt% or less, and in this case, the best efficiency can be obtained.
  • the reactor is preferably maintained at an internal temperature between 500 K and 1500 K and a pressure between 0.5 atm and 100 atm in view of reaction efficiency and economic efficiency.
  • the water splitting reaction may be carried out at a temperature of 373 K or higher, but when the reaction temperature is lower than 500 K, the efficiency of water splitting will decrease.
  • the reaction temperature is preferably between 500 K and 1500 K.
  • the pressure of the water splitting reaction is preferably between 0.5 atm and 100 atm.
  • a reactor made of a heat-resistant and pressure-resistant is used.
  • the reactor In the water splitting reaction, the reactor is maintained at a temperature of 500 ⁇ 1500 K and a pressure of 100 atm or lower.
  • a reactor made of a heat-resistant and pressure-resistant material is used such that the water splitting reaction is stably carried out in the above temperature and pressure ranges.
  • the heat-resistant and pressure-resistant material has an iron content of 70% or higher, and examples thereof include SUS (stainless steel), carbon steel, or a mixture thereof. If the reactor is made of a material which is not iron, the material can be rusted at high temperature and high pressure, because it has low melting temperature, or the reactor itself can influence chemical reactions. Accordingly, when a reactor made of a material having a melting temperature of 1700 ? or higher and an iron content of 70% or higher is used, it will not influence reactions even at high temperature and high pressure.
  • FIG. 1 is a schematic diagram showing an apparatus for testing of water splitting reactions used in tests of the present invention.
  • a solid acid adsorbed with water is supplied from a solid acid supply container 13 through a supply controller 14 to a reactor 6 made of a heat-resistant and pressure-resistant material such as SUS steel.
  • a reactor 6 made of a heat-resistant and pressure-resistant material such as SUS steel.
  • the reactor 6 is provided with a heater 7 such as a heating wire 180 or is placed in a heating furnace such as a coal burning furnace which is maintained at a temperature of 500 K or higher.
  • the solid acid adsorbed with the water supplied to the reactor 6 splits the water in the reactor 6 which is maintained at a temperature of 500 K or higher, thereby producing hydrogen.
  • the solid acid used in the water splitting reaction is discharged from the reactor through a solid discharge controller 8 and introduced into a solid acid cooler 9.
  • the high-temperature solid acid introduced into the cooler 9 is cooled to 373 K or lower by water or air, and then transferred to a water adsorbing container 12.
  • the solid acid adsorbs water supplied from a water supply container 10 through a water supply controller, and it is transferred to a solid acid supply container 13.
  • the testing apparatus used in the test of the present invention also comprises a steam supply container 1 and a carrier gas supply container 3 for supplying carrier gas.
  • a steam meter 2 is provided at the outlet of the steam supply container 1, and a gas meter 4 is provided at the outlet of the carrier gas supply container 3.
  • the steam or carrier gas is introduced from the steam supply container 1 or the carrier gas supply container 3 through a gas flow controller 5 into the reactor 6. Meanwhile, the pressure inside the reactor 6 is controlled by a pressure controller collected to the reactor 6.
  • the concentration of hydrogen in a gas mixture discharged from the reactor 6 is measured in a gas chromatography device 16.
  • the reactor 6 (internal volume: 120 ml) in FIG. 1 was heated to an internal temperature of 1000 K by a heater 7, and in this state, argon was injected into a reactor at a rate of 2 ml/min.
  • Each of the solid acids shown in Table 1 below was ground to an average size of about 100 mesh and then placed in the water adsorbing container 12, and water supplied from the water supply container 10 was adsorbed on each solid acid in an amount of 25 wt% based on the total weight of the solid acid adsorbed with water. Then, each solid acid adsorbed with water was transferred into the solid acid supply container 13.
  • the water-adsorbed solid acid transferred into the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at atmospheric pressure (1 atm). From 2 hours after introduction of the water-adsorbed solid acid, the solid acid was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was cooled to 373 K or lower. Then, the solid acid was transferred into the water adsorbing container 12. Meanwhile, in the reactor 6, hydrogen produced by the water splitting reaction on the solid acid was mixed with the carrier gas argon, and the gas mixture was discharged to the outside through the pressure controller 15.
  • the volume content of the hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 1 below.
  • the time shown in Table 1 means the period elapsed after the water-adsorbed solid acid started to be introduced into the reactor.
  • Table 1 Example Name of compound (solid acid) Hydrogen concentration (PPM) 1 hr 2 hr 3 hr 4 hr 5 hr 6 hr 1 Bentonite 2500 3700 4900 4800 4700 4800 2 Alumina 33000 60000 95000 98000 95000 95000 3 Silica 17000 38000 70000 75000 75000 70000 4 Zinc oxide 25000 40000 50000 49000 49000 50000 5 Titanium oxide 36000 55000 60000 58000 60000 59000
  • the production of hydrogen was compared between hydrogen production methods using alumina as a solid acid.
  • the solid acid alumina was ground to an average size of about 100 mesh, and then water was adsorbed on the solid acid in an amount of 25 wt% (based on the total weight).
  • the water-adsorbed solid acid alumina was continuously introduced according to the method of Test Example 1 into the reactor maintained at atmospheric pressure and 1000 K, and the content of a hydrogen product in a gas discharged from the reactor 6 up to 120 hours after the start of the water splitting reaction was measured using the gas chromatography device 16.
  • the cumulative production of hydrogen is shown in Table 2 below.
  • the solid acid alumina was ground to an average size of about 100 mesh, and then 60 g of the alumina powder was taken and placed in the reactor 6 of FIG. 1. Then, steam from the steam supply container was introduced into the reactor 6 maintained at 323 K or lower so that 20 g of water was adsorbed on the solid acid. Then, the temperature of the reactor 6 was increased to and maintained at 1000 K, while a hydrogen production reaction by water splitting was carried out at atmospheric pressure (1 atm) for 5 hours. Then, the temperature of the reactor 6 was decreased to 323 K over 4 hours, and water adsorption, the hydrogen production reaction by water splitting, and reducing the temperature of the reactor were repeated at 12-hr intervals. The content of a hydrogen product in a gas discharged from the reactor 6 was measured using the gas chromatography device 16 up to 120 hours after the start of the reaction, and the cumulative production of hydrogen is shown in Table 2 below (Comparative Example 1).
  • FIG. 2 shows the testing apparatus used in Comparative Example 2. Specifically, a mixer/evaporator 60 and a temperature control zone 90 were maintained at a temperature of 573 K, and a water splitting reactor 100 was maintained at a temperature of 1000 K.
  • a heating wire 180 is an apparatus for heating the reactor.
  • Argon was injected into the reaction system at a flow rate of 50 ml/min, and the internal pressure of the reaction system was controlled to 5 atm by a pressure controller 130, after which the flow rate of the argon was reduced to 2 ml/min. Then, water was injected into the mixer/evaporator at a rate of 1 g/hr while a hydrogen production reaction by water splitting was started. The content of a hydrogen product in the gas discharged from the reactor 100 was measured up to 120 hours after the start of the reaction using a gas chromatography device 170, and the cumulative production of hydrogen is shown in Table 2 below (Comparative Example 2).
  • the difference of hydrogen production between the inventive method of producing hydrogen by splitting of water and the methods of Comparative Examples 1 and 2 increased as the reaction time increased.
  • the water splitting reaction could not be carried out during the process of cooling the reactor and the process of adsorbing water on the solid acid placed in the reactor.
  • the process of adsorbing water on the solid acid and the process of splitting water were carried out at the same high temperature, and for this reason, high reaction pressure was required to adsorb water on the solid acid, and the amount of water adsorbed on the solid acid could also not be controlled.
  • the characteristics of the water splitting reaction as a function of reaction temperature were examined using the solid acid silica.
  • the reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to the internal temperatures shown in Table 3 below, and in this state, argon was injected into the reactor at a rate of 2 ml/min.
  • the solid acid silica was ground to an average size of about 100 mesh and placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the solid acid silica in an amount of 25 wt% based on the total weight.
  • the solid acid silica adsorbed with water was transferred to the solid acid supply container.
  • the water-adsorbed solid acid silica transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at atmospheric pressure (1 atm). From 2 hours after introduction of the water-adsorbed solid acid silica, the solid acid silica was discharged from the reactor 6 at a rate of 0.4 g/min to the solid acid cooler 9, and it was cooled to a temperature of 373 K or lower and then transferred again to the water adsorbing container 12. Meanwhile, in the reactor, hydrogen produced by the water splitting reaction on the solid acid silica was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor.
  • the volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 3 below.
  • the time in Table 3 means the period elapsed after the solid acid silica started to be introduced into the reactor 6.
  • the characteristics of the water splitting reaction were examined at various reaction pressures using the solid acid titanium oxide.
  • the reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate 2 ml/min.
  • the solid acid titanium oxide was ground to an average size of about 100 mesh and placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the solid acid titanium oxide in an amount of 25 wt% based on the total weight. Then, the solid acid titanium oxide adsorbed with water was transferred to the solid acid supply container.
  • the water-adsorbed solid acid titanium dioxide transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at the pressures shown in Table 4 below. From 2 hours after introduction of the solid acid titanium oxide, the solid acid was discharged from the reactor at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled solid acid titanium oxide was transferred again to the water adsorbing container 12. Meanwhile, in the reactor, hydrogen produced by the water splitting reaction on the solid acid titanium oxide was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor through the pressure controller.
  • the volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 4 below.
  • the time in Table 4 means the period elapsed after the water-adsorbed solid acid titanium oxide started to be introduced into the reactor.
  • the characteristics of the water splitting reaction were examined using mixtures of solid acid and various metal powders.
  • the reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate of 2 ml/min.
  • 100-mesh zinc oxide was taken and each of the 100-mesh metal powders shown in Table 5 was added thereto in an amount of 5 wt% based on the weight of the zinc oxide.
  • each mixture was placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the zinc oxide/metal mixture in an amount of 25 wt% based on the total weight. Then, the water-adsorbed zinc oxide/metal oxide was transferred to the solid acid supply container 13.
  • the water-adsorbed zinc oxide/metal mixture transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at atmospheric pressure (1 atm). From 2 hours after introduction of water-adsorbed zinc oxide/metal mixture, the mixture was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled mixture was transferred again to the water adsorbing container 12. Meanwhile, in the reactor 6, hydrogen produced by the water splitting reaction on the solid acid zinc oxide/metal mixture was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor through the pressure controller 15.
  • the volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 5 below.
  • the time in Table 5 means the period elapsed after the water-adsorbed solid acid zinc oxide/metal mixture started to be introduced into the reactor.
  • the reactor 6 (internal volume: 120 ml) of FIG. 7 was heated by the heater to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate of 2 ml/min.
  • the 100-mesh solid acid alumina was taken and 100-mesh iron powder was added in an amount of 5-30 wt% based on the weight of the solid acid alumina.
  • the mixture was placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the solid acid/iron powder mixture in an amount of 25 wt% based on the total weight.
  • the solid acid alumina/iron powder mixture adsorbed with water was transferred to the solid acid supply container 13.
  • the water-adsorbed solid acid alumina/iron powder mixture transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor maintained at atmospheric pressure (1 atm). From 2 hours after introduction of the solid acid, the solid acid/iron mixture was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled mixture was transferred again to the water adsorbing container 12. Meanwhile, in the reactor 6, hydrogen produced by the water splitting reaction on the solid acid alumina/iron powder mixture was mixed with the carrier gas argon, and the mixed gas discharged from the reactor through the pressure controller 15.
  • the volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 6 below.
  • the time in Table 6 means the period elapsed after the water-adsorbed solid acid started to be introduced into the reactor.
  • the characteristics of the water splitting reaction were examined using a solid acid coated with a metal.
  • the reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate of 2 ml/min. 100-mesh solid acid zinc oxide was taken and 100-mesh electrolyte powder was added in an amount of 5 wt% based on the weight of solid acid zinc oxide. Then, the mixture was placed in the water adsorbing container 12, and water from the water supply container 10 was coated on the solid acid zinc oxide/electrolyte mixture in an amount of 25 wt% based on the total weight. Then, the solid acid zinc oxide/electrolyte mixture adsorbed with water was transferred to the solid acid supply container 13.
  • the water-adsorbed solid acid zinc oxide/electrolyte mixture transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor maintained at atmospheric pressure (1 atm). From 2 hours from introduction of the water-adsorbed solid acid zinc oxide/electrolyte mixture, the mixture was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled mixture was transferred again to the water adsorbing container 12.
  • hydrogen produced by the water splitting reaction on the zinc oxide/electrolyte mixture was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor through the pressure controller 15.
  • the volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 8 below.
  • the time in Table 8 means the period elapsed after the solid acid zinc oxide/electrolyte mixture started to be introduced into the reactor.
  • 100-mesh iron powder was added to 100-mesh solid acid alumina in an amount of 20 wt% based on the weight of the solid acid alumina, KOH was deposited on the mixture in an amount of 5-20 wt% based on the weight of the mixture, in which the amount of KOH deposited was increased at a rate of 5 wt%.
  • a test was carried out under the same conditions as Test Example 7, and the results of the test are shown in Table 10 below.
  • the economic efficiency of producing hydrogen by thermal splitting of water can be increased, and thus the production of hydrogen by thermal splitting of water can be commercialized.

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Abstract

The present invention relates to a method of producing hydrogen by splitting water on a solid acid material. Specifically, the method comprises: continuously introducing a water-adsorbed solid acid into a reactor made of a heat-resistant and pressure-resistant material in a state in which the internal temperature of the reactor is maintained at 500~1500 K; splitting the water adsorbed on the solid acid to produce hydrogen; discharging the solid acid used in the splitting of the water from the reactor; adsorbing water on the discharged solid acid; and introducing the water-adsorbed solid acid again into the reactor. According to the invention, the amount of hydrogen produced by splitting of water can be increased by adsorbing a desired amount of water on a solid acid and continuously introducing the water-adsorbed solid acid into a reactor.

Description

METHOD OF PRODUCING HYDROGEN BY SPLITTING WATER ON SOLID ACID MATERIALS
The present invention relates to a method of producing hydrogen by splitting water.
Human beings have continuously used fossil fuels such as petroleum and coal. The combustion of fossil fuels has produced large amounts of warming gases such as carbon dioxide to cause the global warming phenomenon, and as a result, global environment disruption has been continued, and eventually reached a stage in which the fall of mankind should be feared. In order to this disaster of the earth and mankind, efforts need to be made to suppress the production of global warming gases such as carbon dioxide by limiting the use of fossil gases. Thus, in recent years, studies on the use of nuclear energy, solar energy, and hydrogen energy produced from water have increased. However, the raw material of nuclear energy will be exhausted in the future. On the other hand, solar energy that is supplied infinitely and hydrogen energy that can be continuously produced by spilling water appear to be highly valuable as future energy. Particularly, in view of the current technical level, hydrogen energy appears to be the only solution for driving systems such as automobiles.
Conventional methods of producing hydrogen using water as a raw material include electrolytic methods, which use electrical energy, and thermal decomposition methods which use thermal energy.
The electrolytic methods should employ high-grade energy (electricity) and have low water splitting efficiency. On the other hand, the thermal decomposition methods may be methods which use primary fuel or solar cell and include a one-step direct decomposition method, and a two-step indirect decomposition method of producing hydrogen by thermally decomposing a metal oxide into a metal and oxygen and then allowing the metal to react with water. However, in the direct decomposition method, a reaction temperature of at least 2500 K is required, and in the indirect decomposition method, the temperature for decomposing a metal oxide is required to be at least 1500 K. Thus, the thermal decomposition methods have problems associated with the material of a reaction system due to high reaction temperatures, in addition to a problem in that thermal efficiency is reduced. Due to such problems, the thermal decomposition methods are not commercially used.
In order to solve these problems associated with high temperature reactions, the applicants previously developed a method of producing hydrogen using a mixture of either solid acids or materials selected from solid acids and metals under the reaction conditions of 5-100 atm and 500-1500 K while continuously injecting water and carrier gas into a reactor (Korean Patent Registration No. 983474). However, in this method, a process of adsorbing on solid acids and a process of splitting water are carried out at high reaction temperatures, and thus there are problems in that high reaction pressure is required to adsorb water on the solid acids and the amount of water adsorbed on the solid acids cannot be controlled.
It is an object of the present invention to solve the above-described problems while improving the efficiency of hydrogen production. Another object of the present invention is to enable hydrogen to be commercially produced by thermal splitting of water.
To achieve the above objects, a method of producing hydrogen by thermal splitting of water, the method comprising the steps of: (a) adding water or steam to a solid acid or a solid acid mixture of the solid acid with at least one material selected from a metal and an electrolyte so as to adsorb water on the solid acid or the solid acid mixture; (b) introducing the water-adsorbed solid acid or solid acid mixture into a reactor made of a heat-resistant and pressure-resistant material, and splitting the water on the introduced solid acid or solid acid mixture to produce hydrogen; and (c) discharging the solid acid or solid acid mixture, used in the splitting of the water, from the reactor.
In one embodiment of the present invention, the production method may comprise repeating steps (a) to (c).
In one embodiment of the present invention, the production method may comprise cooling the solid acid or solid acid mixture discharged in step (c) to a temperature of 273~373 K, adding water or steam thereto to adsorb water on the solid acid or the solid acid mixture, and then repeating steps (b) and (c).
In one embodiment of the present invention, the production method may further comprise a step of discharging a hydrogen-containing product from the reactor and measuring the content of hydrogen in the hydrogen-containing product by gas chromatography.
In one embodiment of the present invention, step (b) of the production method may comprise maintaining the inside of the reactor in step (b) at a temperature between 500 K to 1500 K and a pressure between 0.5 atm and 100 atm.
In one embodiment of the present invention may further comprise, before step (b), a step of injecting carrier gas into the reactor, and after step (b), a step of discharging a gas product from the reactor in a mixture with the carrier gas.
In one embodiment of the present invention, the carrier gas may be selected from the group consisting of hydrogen, nitrogen, argon, carbon dioxide, and steam.
In one embodiment of the present invention, in step (c) of the production step, the solid acid or solid acid mixture used in the splitting of the water may be discharged from the reactor at a specific rate from 5 minutes to 5 hours after introduction thereof.
In another embodiment of the present invention, the solid acid may be any one or a mixture of two or more selected from the group consisting of basalt, granite, limestone, sandstone, kaolinite, attapulgite, bentonite, montmorillonite, zinc oxide (ZnO), aluminum oxide (Al2O3), titanium oxide (TiO2), cesium oxide (CeO2), vanadium oxide (V2O5), silicon oxide (SiO2), chromium oxide (Cr2O3), calcium sulfate (CaSO4), manganese sulfate (MnSO4), nickel sulfate (NiSO4), copper sulfate (CuSO4), cobalt sulfate (CoSO4), cadmium sulfate (CdSO4), magnesium sulfate (MgSO4), iron (II) sulfate (FeSO4), aluminum sulfate (Al2(SO4)3), calcium nitrate (Ca(NO3)2), zinc nitrate (Zn(NO3)2), iron (III) nitrate (Fe(NO3)3), aluminum phosphate (AlPO4), iron (III) phosphate (FePO4), chromium phosphate (CrPO4), copper phosphate (Cu3(PO4)2), zinc phosphate (Zn3(PO4)4), magnesium phosphate (Mg3(PO4)2), aluminum chloride (AlCl3), titanium chloride (TiCl4), calcium chloride (CaCl2), calcium fluoride (CaF2), barium fluoride (BaF2), calcium carbonate (CaCO3) and magnesium carbonate (MgCO3).
In one embodiment of the present invention , the metal may be any one or a mixture of two or more selected from the group consisting of aluminum, zinc, iron, cobalt, manganese, chromium and nickel.
In one embodiment of the present invention, the electrolyte may be any one or a mixture of two or more selected from the group consisting of sodium chloride (NaCl), potassium chloride (KCl), sodium nitrate (NaNO3), potassium nitrate (KNO3), sodium sulfate (Na2SO4), potassium sulfate (K2SO4), lithium carbonate (Li2CO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), sodium dihydrogen phosphate (NaH2PO4), sodium monohydrogen phosphate (Na2HPO4), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium chloride (CaCl2), magnesium chloride (MgCl2), calcium nitrate (Ca(NO3)2), magnesium nitrate (Mg(NO3)2), calcium sulfate (CaSO4), magnesium sulfate (MgSO4), calcium hydroxide (Ca(OH)2) and magnesium hydroxide (Mg(OH)2).
In one embodiment of the present invention, each of the solid acid, the metal and the electrolyte may be in the form of powder and may have a particle size of 20-500 mesh.
In one embodiment of the present invention, the solid acid mixture of the solid acid with the metal may comprise metal particles deposited in the pores of solid acid powder, in which the metal particles have a diameter of 10 ㎛ or less.
In one embodiment of the present invention, the solid acid mixture of the solid acid with the metal may comprise either metal powder coated on the surface of solid acid powder or solid acid powder coated on the surface of metal powder, in which the metal powder or the solid acid powder may be coated to a thickness more than 10 nm and 10 ㎛ or less.
In one embodiment of the present invention, the solid acid mixture of the solid acid with the metal may comprise 60 wt% or more of the solid acid and 40 wt% or less of the metal.
In one embodiment of the present invention, the solid acid mixture of the solid acid with the metal and the electrolyte may comprise electrolyte particles deposited in the pores of a mixture of solid acid and metal, in which the electrolyte particles may have a diameter of 10 ㎛ or less.
In one embodiment of the present invention, the solid acid mixture of the solid acid with the metal and the electrolyte may comprise either electrolyte powder coated on the surfaces of solid acid and metal powders or solid acid powder coated on the surface of metal and electrolyte powders, in which the electrolyte powder or the solid acid film powder may be coated to a thickness more than 10 nm and 10 ㎛ or less.
In one embodiment of the present invention, the solid acid mixture of the solid acid with the metal and the electrolyte may comprise 70 wt% or more of the solid acid/metal mixture and 30 wt% or less of the metal.
In one embodiment of the present invention, the reactor may be made of SUS (stainless steel), carbon steel, or a mixture thereof, which has an iron content of 70% or more.
In the inventive method for producing hydrogen, a solid acid adsorbed with a maximum amount of water is continuously introduced into a reactor which is maintained at a specific temperature and a specific pressure, whereby continuous splitting of water in the reactor is possible, thereby increasing the production of hydrogen. Accordingly, the economic efficiency of producing hydrogen by thermal splitting of water can be increased, and thus the production of hydrogen by thermal splitting of water can be commercialized.
FIG. 1 is a schematic diagram showing an apparatus for testing of water splitting reactions used in the test examples of the present invention.
FIG. 2 is a schematic diagram showing a testing apparatus used in Comparative Example 2.
[Description of reference numerals used in the drawings]
1: water supply container; 2: steam meter;
3: carrier gas supply container; 4: gas flow meter;
5: flow controller; 6: reactor;
7: heater; 8: solid acid discharge controller;
9: solid acid cooler; 10: water supply container;
11: water supply controller;
12: solid acid adsorbing container;
13: solid acid supply container;
14: solid acid supply controller;
15: pressure controller; 16: gas chromatography device;
25: gas supply container; 20: water storage container;
30: flow meter; 40: liquid flow meter;
50: gas flow meter; 60: mixer/evaporator;
70: liquid flow controller; 80: gas flow controller;
90: temperature control zone; 100: reactor;
110: temperature meter; 120: pressure meter;
130: pressure controller; 140: 3-way valve;
150: sampling container; 160: temperature controller;
170: gas chromatography device;
180: heating wire.
Hereinafter, the present invention will be described in detail.
A method of producing hydrogen by splitting of water according to the present invention is as follows. Step (a): a solid acid, a metal/solid acid mixture, an electrolyte/solid acid mixture or a metal/electrolyte/solid acid mixture is placed in a water adsorbing container 12, and a desired amount of water or steam is introduced into the water adsorbing container 12 so that liquid-state water is adsorbed on the solid acid or the solid acid mixture. Step (b): the solid acid or solid acid mixture adsorbed with water is continuously introduced into a reactor 6 made of a heat-resistant and pressure-resistant material. The solid acid or solid acid mixture introduced into the reactor is maintained in the reactor for a time period ranging from 5 minutes to 5 hours while it splits water to generate hydrogen as a reaction product. Step (c): the solid acid or solid acid mixture used in the water splitting reaction is discharged from the reactor. The solid acid or solid acid mixture used in the water splitting reaction may be discharged from the reactor through a solid acid discharge controller 8 at a specific rate from 5 minutes to 5 hours after introduction thereof. In the production method of the present invention, steps (a) to (c) may be repeatedly carried out, whereby hydrogen can be continuously produced in the reactor.
The production method of the present invention may comprise cooling the solid acid or solid acid mixture discharged in step (c) to a temperature of 273~373 K, adding water or steam thereto to adsorb water, and then repeating steps (b) and (c) to introduce the solid acid or the solid acid mixture again into the reactor. The solid acid maintained in the reactor for 5 minutes to 5 hours is discharged from the reactor and cooled by a solid acid cooler 9. The cooled solid acid is adsorbed again with water in the water adsorbing container 12 and introduced again into the reactor. These processes are repeated, whereby hydrogen is continuously produced in the reactor.
The production method of the present invention may further comprise a step of discharging a hydrogen gas product from the reactor and measuring the hydrogen content of the discharged hydrogen gas product by a gas chromatography device 16.
The method of the present invention may further comprise, before step (b), a step of injecting carrier gas into the reactor, and after step (b), a step of discharging a gas product from the reactor in a mixture with the carrier gas. The carrier gas can be introduced from a gas supply container 3 through a gas flow meter 5 into the reactor 6. The carrier gas can be discharged from the reactor 6 through a pressure controller 15. When the carrier gas is passed through the reactor, hydrogen, oxygen and steam, which are produced in the reactor, can be smoothly moved to the outside of the reactor. The carrier gas may be selected from the group consisting of hydrogen, nitrogen, argon, carbon dioxide, and steam.
Reaction scheme 1 below schematically shows a water splitting reaction on the solid acid. Referring to reaction scheme 1, water is adsorbed on the Lewis acid site of the solid acid by a coordinate bond to form a Bronsted acid site which then forms a hydrogen bond with the oxygen of the solid acid, whereby water is adsorbed on the solid acid by the two types of bonds (coordinate bond and hydrogen bond). When the solid acid adsorbed with water by the two bonds is heated, electrons are exchanged through the two bonds while the water adsorbed on the solid acid is electrolyzed into hydrogen and a hydroxyl radical.
[Reaction Scheme 1]
[Rectified under Rule 91 11.07.0012]
Figure WO-DOC-MATHS-58
In the water splitting reaction described above, the efficiency of water splitting can be maximized by adsorbing liquid-state liquid on the solid acid.
The solid acid that is used in the present invention may be any one or a mixture of two or more selected from the group consisting of basalt, granite, limestone, sandstone, kaolinite, attapulgite, bentonite, montmorillonite, zinc oxide (ZnO), aluminum oxide (Al2O3), titanium oxide (TiO2), cesium oxide (CeO2), vanadium oxide (V2O5), silicon oxide (SiO2), chromium oxide (Cr2O3), calcium sulfate (CaSO4), manganese sulfate (MnSO4), nickel sulfate (NiSO4), copper sulfate (CuSO4), cobalt sulfate (CoSO4), cadmium sulfate (CdSO4), magnesium sulfate (MgSO4), iron (II) oxide (FeSO4), aluminum sulfate (Al2(SO4)3), calcium nitrate (Ca(NO3)2), zinc nitrate (Zn(NO3)2), iron (III) nitrate (Fe(NO3)3), aluminum phosphate (AlPO4), iron (III) phosphate (FePO4), chromium phosphate (CrPO4), copper phosphate (Cu3(PO4)2), zinc phosphate (Zn3(PO4)4), magnesium phosphate (Mg3(PO4)2), aluminum chloride (AlCl3), titanium chloride (TiCl4), calcium chloride (CaCl2), calcium fluoride (CaF2), barium fluoride (BaF2), calcium carbonate (CaCO3) and magnesium carbonate (MgCO3).
In the present invention, the solid acid may be used in a mixture with a metal. In this case, the metal can increase the efficiency of water splitting at a reaction temperature of 1500 K or lower. This is because electron transfer is more activated by the metal in a process in which the surface electrons of the solid acid move to the hydrogen ions of water. The metal that is used in the present invention may be any one or a mixture or alloy of two or more selected from the group consisting of aluminum, zinc, iron, cobalt, manganese, chromium and nickel.
Each of the solid acid and the metal, which are used in the present invention, may be in the form of powder and may have a particle size of 20-500 mesh. As the particle sizes of the solid acid powder and the metal power become smaller, the surface areas thereof become larger. Thus, as the particle sizes become smaller, the efficiency of the water splitting reaction becomes higher. However, if the sizes of the particles are larger than 500 mesh, the particles can be lost from the reactor by the flow of the carrier gas, and if the particle size is smaller than 20 mesh, the reaction efficiency can greatly decrease. For this reason, the sizes of the solid acid power and the metal powder are preferably 20-500 mesh in view of reactivity and process maintenance.
The metal/solid acid mixture which is used in the present invention may be composed of metal particles deposited in the pores of the solid acid powder. In this case, the diameter of the metal particles is 10 ㎛ or less, because the reaction efficiency decreases as the size of the metal particles increases.
The metal/solid acid mixture that is used in the present invention may comprise either metal powder coated on the surface of solid acid powder or solid acid powder coated on the surface of metal powder, in which the metal powder or the solid acid powder may be coated to a thickness more than 10 nm and 10 ㎛ or less. When the metal powder or the solid acid powder is coated to a thickness more than 10 nm and 10 ㎛ or less, good reaction efficiency will be ensured.
The metal/solid acid mixture that is used in the present invention may comprise 60 wt% or more of the solid acid and 40 wt% or less of the metal. If the metal powder is contained in an amount of more than 40 wt%, a reaction between the metal powder and water will predominantly occur, and thus splitting of water by the solid acid will significantly decrease. Accordingly, more preferably, the content of the metal powder is maintained at 20 wt% or less, and in this case, the best efficiency can be obtained.
In the present invention, the solid acid/metal mixture may be used in a mixture with an electrolyte, and in this case, the efficiency of water splitting can be increased by the electrolyte. This is because electron transfer is more activated by the electrolyte in a process in which the surface electrons of the solid acid move to the hydrogen ions of water.
The electrolyte that is used in the present invention may be any one or a mixture of two or more selected from the group consisting of sodium chloride (NaCl), potassium chloride (KCl), sodium nitrate (NaNO3), potassium nitrate (KNO3), sodium sulfate (Na2SO4), potassium sulfate (K2SO4), lithium carbonate (Li2CO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), sodium dihydrogen phosphate (NaH2PO4), sodium monohydrogen phosphate (Na2HPO4), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium chloride (CaCl2), magnesium chloride (MgCl2), calcium nitrate (Ca(NO3)2), magnesium nitrate (Mg(NO3)2), calcium phosphate (CaSO4), magnesium sulfate (MgSO4), calcium hydroxide (Ca(OH)2) and magnesium hydroxide (Mg(OH)2).
Each of the solid acid, the metal and the electrolyte which are used in the present invention may be in the form of powder and may have a particle size of 20-500 mesh. As the particle sizes of the solid acid powder, the metal powder and the electrolyte powder become smaller, the surface areas thereof become larger. Thus, as the particles sizes become smaller, the efficiency of the water splitting reaction becomes higher. However, if the size of the particles is larger than 500 mesh, the particles can be lost from the reactor can be lost from the reactor by the flow of the carrier gas, and if the particle size is smaller than 20 mesh, the efficiency of the water splitting reaction can greatly decrease. Therefore, the sizes of the solid acid powder and the metal powder are preferably 20-500 mesh in view of reactivity and process maintenance.
The metal/electrolyte/solid acid mixture that is used in the present invention may comprise electrolyte particles deposited in the pores of a solid acid/metal mixture. In this case, the electrolyte particles deposited in the pores of the solid acid and metal powders preferably have a diameter of 10 ㎛, because the efficiency of the water splitting reaction increases as the size of the electrolyte particles decreases.
The metal/electrolyte/solid acid mixture that is used in the present invention may comprise either electrolyte powder coated on the surfaces of solid acid and metal powders or solid acid powder coated on the surfaces of metal and electrolyte powders, in which the electrolyte powder or the solid acid powder may be coated to a thickness more than 10 nm and 10 ㎛ or less. When the electrolyte powder or the solid acid powder is coated to a thickness more than 10 nm and 10 ㎛ or less, good reaction efficiency will be ensured.
The metal/electrolyte/solid acid mixture that is used in the present invention may comprise 70 wt% or more of the solid acid/metal mixture and 30 wt% or less of the electrolyte. If the electrolyte powder is contained in an amount of more than 30 wt%, the electrolyte will significantly interfere with the movement of electrons, and thus the efficiency of water splitting by the solid acid will significantly decrease. Thus, the content of the electrolyte powder is more preferably maintained at 15 wt% or less, and in this case, the best efficiency can be obtained.
In the water splitting reaction in step (b) of the method of the present invention, the reactor is preferably maintained at an internal temperature between 500 K and 1500 K and a pressure between 0.5 atm and 100 atm in view of reaction efficiency and economic efficiency.
The water splitting reaction may be carried out at a temperature of 373 K or higher, but when the reaction temperature is lower than 500 K, the efficiency of water splitting will decrease. As the reaction temperature increase, the efficiency of water splitting increase, but when the reaction temperature is higher than 1500 K, the degree of an increase in the efficiency of water splitting will greatly decrease. Therefore, the reaction temperature is preferably between 500 K and 1500 K.
In the water splitting reaction on the solid acid, the amount of water adsorbed on the solid acid increases as the reaction pressure increases. Thus, as the reaction pressure increases, the production of hydrogen increases. However, as the reaction pressure increases, the rate of the water splitting reaction gradually decreases, and when the reaction pressure is higher than 100 atm, water splitting efficiency per unit time will greatly decrease. In addition, as the reaction pressure decreases, the rate of the water splitting reaction advantageously increases, but the production of hydrogen decreases. Particularly, if the reaction pressure is decreased to lower than 0.5 atm, additional costs will increase, and thus the economic efficiency of producing hydrogen by splitting of water will greatly decrease. Accordingly, the pressure of the water splitting reaction is preferably between 0.5 atm and 100 atm.
Meanwhile, in the method of producing hydrogen by splitting of water according to the present invention, a reactor made of a heat-resistant and pressure-resistant is used. In the water splitting reaction, the reactor is maintained at a temperature of 500~1500 K and a pressure of 100 atm or lower. Thus, a reactor made of a heat-resistant and pressure-resistant material is used such that the water splitting reaction is stably carried out in the above temperature and pressure ranges. The heat-resistant and pressure-resistant material has an iron content of 70% or higher, and examples thereof include SUS (stainless steel), carbon steel, or a mixture thereof. If the reactor is made of a material which is not iron, the material can be rusted at high temperature and high pressure, because it has low melting temperature, or the reactor itself can influence chemical reactions. Accordingly, when a reactor made of a material having a melting temperature of 1700 ? or higher and an iron content of 70% or higher is used, it will not influence reactions even at high temperature and high pressure.
Hereinafter, the present invention will be described in further detail with reference to examples, comparative examples and test examples. However, the scope of the present invention is not limited to these examples, comparative examples and test examples, and the present invention can be embodied in various forms without departing from the scope of the present invention as set forth in the appended claims. These examples, comparative examples and test examples are provided to complete the disclosure of the present invention and to enable those skilled in the art to easily carry out the present invention.
[Testing apparatus]
FIG. 1 is a schematic diagram showing an apparatus for testing of water splitting reactions used in tests of the present invention.
Referring to FIG. 1, a solid acid adsorbed with water is supplied from a solid acid supply container 13 through a supply controller 14 to a reactor 6 made of a heat-resistant and pressure-resistant material such as SUS steel. In order to maintain the inside of the reactor 6 at a temperature of 500 K or higher, the reactor 6 is provided with a heater 7 such as a heating wire 180 or is placed in a heating furnace such as a coal burning furnace which is maintained at a temperature of 500 K or higher.
Thus, the solid acid adsorbed with the water supplied to the reactor 6 splits the water in the reactor 6 which is maintained at a temperature of 500 K or higher, thereby producing hydrogen. Meanwhile, the solid acid used in the water splitting reaction is discharged from the reactor through a solid discharge controller 8 and introduced into a solid acid cooler 9. The high-temperature solid acid introduced into the cooler 9 is cooled to 373 K or lower by water or air, and then transferred to a water adsorbing container 12. In the water adsorbing container, the solid acid adsorbs water supplied from a water supply container 10 through a water supply controller, and it is transferred to a solid acid supply container 13.
The testing apparatus used in the test of the present invention also comprises a steam supply container 1 and a carrier gas supply container 3 for supplying carrier gas. A steam meter 2 is provided at the outlet of the steam supply container 1, and a gas meter 4 is provided at the outlet of the carrier gas supply container 3. The steam or carrier gas is introduced from the steam supply container 1 or the carrier gas supply container 3 through a gas flow controller 5 into the reactor 6. Meanwhile, the pressure inside the reactor 6 is controlled by a pressure controller collected to the reactor 6.
The concentration of hydrogen in a gas mixture discharged from the reactor 6 is measured in a gas chromatography device 16.
[Test Example 1: Examination of reaction characteristics according to the kind of solid acid]
The characteristics of the water splitting reaction according to the kind of solid acid were examined using the testing apparatus of FIG. 1.
The reactor 6 (internal volume: 120 ml) in FIG. 1 was heated to an internal temperature of 1000 K by a heater 7, and in this state, argon was injected into a reactor at a rate of 2 ml/min. Each of the solid acids shown in Table 1 below was ground to an average size of about 100 mesh and then placed in the water adsorbing container 12, and water supplied from the water supply container 10 was adsorbed on each solid acid in an amount of 25 wt% based on the total weight of the solid acid adsorbed with water. Then, each solid acid adsorbed with water was transferred into the solid acid supply container 13. The water-adsorbed solid acid transferred into the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at atmospheric pressure (1 atm). From 2 hours after introduction of the water-adsorbed solid acid, the solid acid was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was cooled to 373 K or lower. Then, the solid acid was transferred into the water adsorbing container 12. Meanwhile, in the reactor 6, hydrogen produced by the water splitting reaction on the solid acid was mixed with the carrier gas argon, and the gas mixture was discharged to the outside through the pressure controller 15. The volume content of the hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 1 below. The time shown in Table 1 means the period elapsed after the water-adsorbed solid acid started to be introduced into the reactor.
Table 1
Example Name of compound (solid acid) Hydrogen concentration (PPM)
1 hr 2 hr 3 hr 4 hr 5 hr 6 hr
1 Bentonite 2500 3700 4900 4800 4700 4800
2 Alumina 33000 60000 95000 98000 95000 95000
3 Silica 17000 38000 70000 75000 75000 70000
4 Zinc oxide 25000 40000 50000 49000 49000 50000
5 Titanium oxide 36000 55000 60000 58000 60000 59000
As can be seen in Table, the production of hydrogen did differ between the solid acids used in this test, but all the solid acids split water to generate considerable amounts of hydrogen. In addition, it can be seen that the concentration of hydrogen was maintained at a constant level from 3 hours after the start of the reaction.
[Comparative Test Example 1: Comparison of hydrogen production]
The production of hydrogen was compared between hydrogen production methods using alumina as a solid acid.
The solid acid alumina was ground to an average size of about 100 mesh, and then water was adsorbed on the solid acid in an amount of 25 wt% (based on the total weight). The water-adsorbed solid acid alumina was continuously introduced according to the method of Test Example 1 into the reactor maintained at atmospheric pressure and 1000 K, and the content of a hydrogen product in a gas discharged from the reactor 6 up to 120 hours after the start of the water splitting reaction was measured using the gas chromatography device 16. The cumulative production of hydrogen is shown in Table 2 below.
Meanwhile, the solid acid alumina was ground to an average size of about 100 mesh, and then 60 g of the alumina powder was taken and placed in the reactor 6 of FIG. 1. Then, steam from the steam supply container was introduced into the reactor 6 maintained at 323 K or lower so that 20 g of water was adsorbed on the solid acid. Then, the temperature of the reactor 6 was increased to and maintained at 1000 K, while a hydrogen production reaction by water splitting was carried out at atmospheric pressure (1 atm) for 5 hours. Then, the temperature of the reactor 6 was decreased to 323 K over 4 hours, and water adsorption, the hydrogen production reaction by water splitting, and reducing the temperature of the reactor were repeated at 12-hr intervals. The content of a hydrogen product in a gas discharged from the reactor 6 was measured using the gas chromatography device 16 up to 120 hours after the start of the reaction, and the cumulative production of hydrogen is shown in Table 2 below (Comparative Example 1).
In addition, the solid acid alumina was ground to an average size of about 100 mesh, and 60 g of the alumina powder was taken and placed in the water splitting reactor 100 shown in FIG. 2 and was subjected to a continuous water splitting reaction at high pressure (Comparative Example 2). FIG. 2 shows the testing apparatus used in Comparative Example 2. Specifically, a mixer/evaporator 60 and a temperature control zone 90 were maintained at a temperature of 573 K, and a water splitting reactor 100 was maintained at a temperature of 1000 K. A heating wire 180 is an apparatus for heating the reactor. Argon was injected into the reaction system at a flow rate of 50 ml/min, and the internal pressure of the reaction system was controlled to 5 atm by a pressure controller 130, after which the flow rate of the argon was reduced to 2 ml/min. Then, water was injected into the mixer/evaporator at a rate of 1 g/hr while a hydrogen production reaction by water splitting was started. The content of a hydrogen product in the gas discharged from the reactor 100 was measured up to 120 hours after the start of the reaction using a gas chromatography device 170, and the cumulative production of hydrogen is shown in Table 2 below (Comparative Example 2).
Table 2
Comparative Test Cumulative hydrogen production (㎖)
Example 24 hr 48 hr 72 hr 96 hr 120 hr
Example 2 265.2 538.8 812.0 1085 1358
Comparative Example 1 74.16 148.32 222.48 296.64 370.80
Comparative Example 2 15.84 43.06 62.79 77.19 77.19
As can be seen in Table 2, the difference of hydrogen production between the inventive method of producing hydrogen by splitting of water and the methods of Comparative Examples 1 and 2 increased as the reaction time increased. In the method of Comparative Example 1, the water splitting reaction could not be carried out during the process of cooling the reactor and the process of adsorbing water on the solid acid placed in the reactor. In the method of Comparative Example 2, the process of adsorbing water on the solid acid and the process of splitting water were carried out at the same high temperature, and for this reason, high reaction pressure was required to adsorb water on the solid acid, and the amount of water adsorbed on the solid acid could also not be controlled.
[Test Example 2: Characteristics of water splitting reaction as a function of reaction temperature]
The characteristics of the water splitting reaction as a function of reaction temperature were examined using the solid acid silica. The reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to the internal temperatures shown in Table 3 below, and in this state, argon was injected into the reactor at a rate of 2 ml/min. The solid acid silica was ground to an average size of about 100 mesh and placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the solid acid silica in an amount of 25 wt% based on the total weight. The solid acid silica adsorbed with water was transferred to the solid acid supply container. The water-adsorbed solid acid silica transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at atmospheric pressure (1 atm). From 2 hours after introduction of the water-adsorbed solid acid silica, the solid acid silica was discharged from the reactor 6 at a rate of 0.4 g/min to the solid acid cooler 9, and it was cooled to a temperature of 373 K or lower and then transferred again to the water adsorbing container 12. Meanwhile, in the reactor, hydrogen produced by the water splitting reaction on the solid acid silica was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor. The volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 3 below. The time in Table 3 means the period elapsed after the solid acid silica started to be introduced into the reactor 6.
Table 3
Example Reaction temperature (K) Hydrogen concentration (PPM)
1 hr 2 hr 3 hr 4 hr 5 hr 6 hr
6 600 110 530 950 970 960 960
7 700 850 4200 6300 6500 6300 6400
8 800 3200 14000 26000 27000 29000 27000
9 900 5100 29000 53000 53000 55000 54000
3 1000 17000 38000 70000 75000 75000 70000
As can be seen in Table 3, in the temperature range inside the reactor 10, set in this test, the production of hydrogen increased as the reaction temperature increased.
[Test Example 3: Characteristics of water splitting reaction as a function of reaction pressure]
The characteristics of the water splitting reaction were examined at various reaction pressures using the solid acid titanium oxide. The reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate 2 ml/min. The solid acid titanium oxide was ground to an average size of about 100 mesh and placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the solid acid titanium oxide in an amount of 25 wt% based on the total weight. Then, the solid acid titanium oxide adsorbed with water was transferred to the solid acid supply container. The water-adsorbed solid acid titanium dioxide transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at the pressures shown in Table 4 below. From 2 hours after introduction of the solid acid titanium oxide, the solid acid was discharged from the reactor at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled solid acid titanium oxide was transferred again to the water adsorbing container 12. Meanwhile, in the reactor, hydrogen produced by the water splitting reaction on the solid acid titanium oxide was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor through the pressure controller. The volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 4 below. The time in Table 4 means the period elapsed after the water-adsorbed solid acid titanium oxide started to be introduced into the reactor.
Table 4
Example Reaction pressure (atm) Hydrogen concentration (PPM)
0 hr 1 hr 2 hr 3 hr 4 hr 5 hr
5 1 36000 55000 60000 58000 60000 59000
10 3 32000 45000 75000 76000 7400 75000
11 5 27000 38000 67000 85000 87000 86000
12 7 24000 34000 64000 90000 91000 90000
13 9 22000 32000 62000 83000 93000 92000
As can be seen in Table 4 above, the peak hydrogen concentration increased as the reaction increased, but the reaction time required to reach the peak hydrogen concentration became longer. In addition, after the peak hydrogen concentration appeared, the hydrogen concentration was maintained at a level similar to the peak hydrogen concentration even with the passage of reaction time.
[Test Example 4: Characteristics of reaction according to addition of metal]
The characteristics of the water splitting reaction were examined using mixtures of solid acid and various metal powders.
The reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate of 2 ml/min. 100-mesh zinc oxide was taken and each of the 100-mesh metal powders shown in Table 5 was added thereto in an amount of 5 wt% based on the weight of the zinc oxide. Then, each mixture was placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the zinc oxide/metal mixture in an amount of 25 wt% based on the total weight. Then, the water-adsorbed zinc oxide/metal oxide was transferred to the solid acid supply container 13. The water-adsorbed zinc oxide/metal mixture transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor 6 maintained at atmospheric pressure (1 atm). From 2 hours after introduction of water-adsorbed zinc oxide/metal mixture, the mixture was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled mixture was transferred again to the water adsorbing container 12. Meanwhile, in the reactor 6, hydrogen produced by the water splitting reaction on the solid acid zinc oxide/metal mixture was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor through the pressure controller 15. The volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 5 below. The time in Table 5 means the period elapsed after the water-adsorbed solid acid zinc oxide/metal mixture started to be introduced into the reactor.
Table 5
Example Name of metal Hydrogen concentration (PPM)
1 hr 2 hr 3 hr 4 hr 5 hr 6 hr
14 Aluminum 42000 85000 110000 120000 110000 110000
15 Zinc 45000 91000 120000 120000 120000 120000
16 Iron 54000 110000 140000 150000 140000 140000
17 Cobalt 49000 99000 130000 130000 130000 130000
18 Nickel 48000 87000 110000 120000 110000 110000
19 Manganese 36000 73000 90000 93000 91000 90000
As can be seen in Table 5 above, in the case in which the water splitting reaction was carried out using the solid acid zinc oxide/metal oxide powder mixtures in the reactor 6, the production of hydrogen increased compared to that in the case in which the water splitting reaction was carried out using the solid acid zinc oxide alone.
[Test Example 5: Characteristics of water splitting reaction as a function of the amount of metal added]
The reactor 6 (internal volume: 120 ml) of FIG. 7 was heated by the heater to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate of 2 ml/min. The 100-mesh solid acid alumina was taken and 100-mesh iron powder was added in an amount of 5-30 wt% based on the weight of the solid acid alumina. Then, the mixture was placed in the water adsorbing container 12, and water from the water supply container 10 was adsorbed on the solid acid/iron powder mixture in an amount of 25 wt% based on the total weight. Then, the solid acid alumina/iron powder mixture adsorbed with water was transferred to the solid acid supply container 13. The water-adsorbed solid acid alumina/iron powder mixture transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor maintained at atmospheric pressure (1 atm). From 2 hours after introduction of the solid acid, the solid acid/iron mixture was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled mixture was transferred again to the water adsorbing container 12. Meanwhile, in the reactor 6, hydrogen produced by the water splitting reaction on the solid acid alumina/iron powder mixture was mixed with the carrier gas argon, and the mixed gas discharged from the reactor through the pressure controller 15. The volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 6 below. The time in Table 6 means the period elapsed after the water-adsorbed solid acid started to be introduced into the reactor.
Table 6
Example Metal amount (wt%) Hydrogen concentration (PPM)
1 hr 2 hr 3 hr 4 hr 5 hr 6 hr
20 5 3800 34000 110000 120000 110000 110000
21 10 4200 39000 120000 130000 120000 120000
22 15 5100 43000 140000 140000 140000 140000
23 20 4000 31000 130000 120000 120000 120000
24 25 4900 36000 90000 90000 88000 90000
25 30 5700 33000 70000 73000 71000 70000
As can be seen in Table 6 above, in the case in which iron powder was added, the amount of hydrogen produced was larger than that in the case in which the test was carried out using the solid acid alumina alone. However, it can be seen that, when the amount of metal powder added was excessively large, the production of hydrogen decreased rather than increased.
[Test Example 6: Examination of characteristics of reaction using solid acid coated with metal]
The characteristics of the water splitting reaction were examined using a solid acid coated with a metal.
The solid acid alumina coated with 100-mesh iron was taken, and a test was carried using the coated material under the same conditions as Test Example 5. The results of the test are shown in Table 7.
Table 7
Example Metal film thickness (㎚) Hydrogen concentration (PPM)
1 hr 2 hr 3 hr 4 hr 5 hr 6 hr
26 100 3800 30000 130000 140000 130000 130000
27 500 4200 35000 150000 160000 150000 150000
28 1000 5100 38000 160000 160000 160000 160000
29 5000 3900 26000 140000 130000 130000 130000
[Test Example 7: Examination of characteristics of reaction using solid acid/electrolyte mixture]
The characteristics of the water splitting reaction were examined using mixtures of solid acid with various electrolytes.
The reactor 6 (internal volume: 120 ml) of FIG. 1 was heated by the heater 7 to an internal temperature of 1000 K, and in this state, argon was injected into the reactor at a rate of 2 ml/min. 100-mesh solid acid zinc oxide was taken and 100-mesh electrolyte powder was added in an amount of 5 wt% based on the weight of solid acid zinc oxide. Then, the mixture was placed in the water adsorbing container 12, and water from the water supply container 10 was coated on the solid acid zinc oxide/electrolyte mixture in an amount of 25 wt% based on the total weight. Then, the solid acid zinc oxide/electrolyte mixture adsorbed with water was transferred to the solid acid supply container 13. The water-adsorbed solid acid zinc oxide/electrolyte mixture transferred to the solid acid supply container was introduced at a rate of 0.5 g/min into the reactor maintained at atmospheric pressure (1 atm). From 2 hours from introduction of the water-adsorbed solid acid zinc oxide/electrolyte mixture, the mixture was discharged from the reactor 6 at a rate of 0.4 g/min and transferred to the solid acid cooler 9 in which it was then cooled to 373 K or lower. The cooled mixture was transferred again to the water adsorbing container 12. In the reactor 6, hydrogen produced by the water splitting reaction on the zinc oxide/electrolyte mixture was mixed with the carrier gas argon, and the mixed gas was discharged from the reactor through the pressure controller 15. The volume content of a hydrogen product in the gas discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 8 below. The time in Table 8 means the period elapsed after the solid acid zinc oxide/electrolyte mixture started to be introduced into the reactor.
Table 8
Example Name of electrolyte Hydrogen concentration (PPM)
1 hr 2 hr 3 hr 4 hr 5 hr 6 hr
30 K2SO4 8000 41000 81000 84000 82000 82000
31 Li2CO3 6500 44000 72000 74000 73000 73000
32 MgCl2 5500 43000 63000 65000 64000 63000
33 Ca(OH)2 6000 38000 66000 68000 67000 67000
As can be seen in FIG. 8, in the case in which the water splitting reaction was carried out using the solid acid zinc oxide/electrolyte powder mixture in the reactor 6, the production of hydrogen increased compared to that in the case in which the reaction was carried out using the solid acid alone.
[Test Example 8: Characteristics of water splitting reaction as a function of the amount of electrolyte added]
100-mesh solid acid alumina was taken and 100-mesh potassium sulfate (K2SO4) powder was added in an amount of 5-30 wt% based on the weight of the solid acid alumina. Then, a test was carried out using the mixture under the same conditions as Example 7. The volume content of a hydrogen product discharged from the reactor 6 was measured using the gas chromatography device 16, and the results of the measurement are shown in Table 9 below.
Table 9
Example Electrolyte amount (wt%) Hydrogen concentration (PPM)
1 hr 2 hr 3 hr 4 hr 5 hr 6 hr
30 5 8000 41000 81000 84000 82000 82000
34 10 9100 49000 89000 91000 90000 90000
35 15 12000 64000 110000 110000 110000 110000
36 20 8500 42000 73000 75000 74000 73000
37 25 7300 31000 57000 56000 55000 55000
38 30 4800 23000 45000 46000 44000 44000
As can be seen in Table 9 above, in the case in which the water splitting reaction was carried out using the mixture containing the potassium sulfate powder, the amount of hydrogen produced was larger than that in the case in which the reaction was carried out using the solid acid alone. However, when the amount of potassium sulfate added was excessively large, the amount of hydrogen produced decreased rather than increased.
[Test Example 9: Examination of characteristics of reaction using a solid acid/metal mixture having an electrolyte deposited thereon]
100-mesh iron powder was added to 100-mesh solid acid alumina in an amount of 20 wt% based on the weight of the solid acid alumina, KOH was deposited on the mixture in an amount of 5-20 wt% based on the weight of the mixture, in which the amount of KOH deposited was increased at a rate of 5 wt%. Using the solid acid alumina/iron powder mixture having 5-25 wt% of KOH deposited thereon, a test was carried out under the same conditions as Test Example 7, and the results of the test are shown in Table 10 below.
Table 10
Example Amount of KOH deposited (wt%) Hydrogen concentration (PPM)
0 hr 1 hr 2 hr 3 hr 4 hr 5 hr
39 5 6700 35000 140000 150000 150000 150000
40 10 7100 45000 170000 170000 170000 170000
41 15 5100 28000 130000 140000 130000 130000
42 20 3900 26000 110000 110000 100000 100000
Although the present invention has been described in detail with reference to the specific features, it will be apparent to those skilled in the art that this description is only for a preferred embodiment and does not limit the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.
In the inventive method for producing hydrogen, the economic efficiency of producing hydrogen by thermal splitting of water can be increased, and thus the production of hydrogen by thermal splitting of water can be commercialized.

Claims (19)

  1. A method of producing hydrogen by thermal splitting of water, the method comprising the steps of:
    (a) adding water or steam to a solid acid or a solid acid mixture of the solid acid and at least one material selected from a metal and an electrolyte so as to adsorb water on the solid acid or the solid acid mixture;
    (b) introducing the water-adsorbed solid acid or solid acid mixture into a reactor made of a heat-resistant and pressure-resistant material, and splitting the water on the introduced solid acid or solid acid mixture to produce hydrogen; and
    (c) discharging the solid acid or solid acid mixture, used in the splitting of the water, from the reactor.
  2. The method of claim 1, wherein steps (a) to (c) are repeated.
  3. The method of claim 1, wherein the method comprises cooling the solid acid or solid acid mixture discharged in step (c) to a temperature of 273~373 K, adding water or steam thereto to adsorb water thereon, and then repeating steps (b) and (c).
  4. The method of claim 1, wherein the method further comprises a step of discharging a hydrogen-containing product from the reactor and measuring the content of hydrogen in the hydrogen-containing product.
  5. The method of claim 1, wherein step (b) comprises maintaining the inside of the reactor in step (b) at a temperature between 500 K to 1500 K and a pressure between 0.5 atm and 100 atm.
  6. The method of claim 1, wherein the method further comprises, before step (b), a step of injecting carrier gas into the reactor, and after step (b), a step of discharging a gas product from the reactor in a mixture with the carrier gas.
  7. The method of claim 6, wherein the carrier gas is selected from the group consisting of hydrogen, nitrogen, argon, carbon dioxide, and steam.
  8. The method of claim 1, wherein, in step (c), the solid acid or solid acid mixture used in the splitting of the water is discharged from the reactor at a specific rate from 5 minutes to 5 hours after introduction thereof.
  9. The method of claim 1, wherein the solid acid is any one or a mixture of two or more selected from the group consisting of basalt, granite, limestone, sandstone, kaolinite, attapulgite, bentonite, montmorillonite, zinc oxide (ZnO), aluminum oxide (Al2O3), titanium oxide (TiO2), cesium oxide (CeO2), vanadium oxide (V2O5), silicon oxide (SiO2), chromium oxide (Cr2O3), calcium sulfate (CaSO4), manganese sulfate (MnSO4), nickel sulfate (NiSO4), copper sulfate (CuSO4), cobalt sulfate (CoSO4), cadmium sulfate (CdSO4), magnesium sulfate (MgSO4), iron (II) sulfate (FeSO4), aluminum sulfate (Al2(SO4)3), calcium nitrate (Ca(NO3)2), zinc nitrate (Zn(NO3)2), iron (III) nitrate (Fe(NO3)3), aluminum phosphate (AlPO4), iron (III) phosphate (FePO4), chromium phosphate (CrPO4), copper phosphate (Cu3(PO4)2), zinc phosphate (Zn3(PO4)4), magnesium phosphate (Mg3(PO4)2), aluminum chloride (AlCl3), titanium chloride (TiCl4), calcium chloride (CaCl2), calcium fluoride (CaF2), barium fluoride (BaF2), calcium carbonate (CaCO3) and magnesium carbonate (MgCO3).
  10. The method of claim 1, wherein the metal is any one selected from the group consisting of aluminum, zinc, iron, cobalt, manganese, chromium and nickel, or a mixture thereof , or an alloy thereof .
  11. The method of claim 1, wherein the electrolyte is any one or a mixture of two or more selected from the group consisting of sodium chloride (NaCl), potassium chloride (KCl), sodium nitrate (NaNO3), potassium nitrate (KNO3), sodium sulfate (Na2SO4), potassium sulfate (K2SO4), lithium carbonate (Li2CO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), sodium dihydrogen phosphate (NaH2PO4), sodium monohydrogen phosphate (Na2HPO4), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium chloride (CaCl2), magnesium chloride (MgCl2), calcium nitrate (Ca(NO3)2), magnesium nitrate (Mg(NO3)2), calcium sulfate (CaSO4), magnesium sulfate (MgSO4), calcium hydroxide (Ca(OH)2) and magnesium hydroxide (Mg(OH)2).
  12. The method of claim 1, wherein each of the solid acid, the metal and the electrolyte is in form of powder and has a particle size of 20-500 mesh.
  13. The method of claim 1, wherein the solid acid mixture of the solid acid and the metal comprises metal particles deposited in the pores of solid acid powder, in which the metal particles have a diameter of 10 ㎛ or less.
  14. The method of claim 1, wherein the solid acid mixture of the solid acid and the metal comprises either metal powder coated on the surface of solid acid powder or solid acid powder coated on the surface of metal powder, in which the metal powder or the solid acid powder is coated to a thickness more than 10nm and 10㎛ or less.
  15. The method of claim 1, wherein the solid acid mixture of the solid acid and the metal comprises 60 wt% or more of the solid acid and 40 wt% or less of the metal.
  16. The method of claim 1, wherein the solid acid mixture of the solid acid with the metal and the electrolyte comprises electrolyte particles deposited in the pores of a mixture of solid acid and metal, in which the electrolyte particles have a diameter of 10 ㎛ or less.
  17. The method of claim 1, wherein the solid acid mixture of the solid acid with the metal and the electrolyte comprises either electrolyte powder coated on the surfaces of solid acid and metal powders or solid acid powder coated on the surfaces of metal and electrolyte powders, in which the electrolyte powder or the solid acid powder is coated to a thickness more than 10nm and 10㎛ or less.
  18. The method of claim 1, wherein the solid acid mixture of the solid acid with the metal and the electrolyte comprises 70 wt% or more of the solid acid/metal mixture and 30 wt% or less of the metal.
  19. The method of claim 1, wherein the reactor is made of SUS (stainless steel), carbon steel, or a mixture thereof, which has an iron content of 70% or more.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014186431A1 (en) * 2013-05-17 2014-11-20 Sunpower Technologies Llc Photo-catalytic systems for production of hydrogen
CN106905112A (en) * 2017-03-07 2017-06-30 王亚壮 A kind of method and system of new synthesizing methanol
CN106955715A (en) * 2017-03-09 2017-07-18 盐城复华环保产业开发有限公司 A kind of biomass gasifying hydrogen making catalyst and preparation method thereof
CN108751144A (en) * 2018-07-03 2018-11-06 贵州大学 A kind of technique of ardealite and low product bauxite overfiring-proof coating coproduction acid
EP3593650A3 (en) * 2018-06-19 2020-03-18 Vivere Alcalino S.r.l. Preparations capable of increasing the ph of food by releasing molecular hydrogen
CN113617340A (en) * 2021-08-18 2021-11-09 甘肃融万科技有限公司 Color-changeable bactericidal attapulgite-based deodorizing and dehumidifying agent and preparation method thereof
CN114029072A (en) * 2021-12-01 2022-02-11 万华化学集团股份有限公司 Solid super acidic catalyst and method for preparing isooctyl p-methoxycinnamate by using same

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004109086A2 (en) * 2003-06-05 2004-12-16 Solar Reactor Technologies, Inc. Method for processing stack gas emissions
WO2005123285A1 (en) * 2004-06-17 2005-12-29 Sorain Cecchini Ambiente Sca S.P.A. Method and system for the recycling of municipal solid wastes, and exploitation of the wasted solid recovery fuel

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100644345B1 (en) * 2005-02-07 2006-11-10 한국과학기술연구원 A catalyst for the disintegration of vapor phase organic compounds and for the organic synthesis from carbon dioxide and water
KR100983474B1 (en) * 2008-08-29 2010-09-24 한국과학기술연구원 Method of producing hydrogen by splitting water using solid acid materials

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004109086A2 (en) * 2003-06-05 2004-12-16 Solar Reactor Technologies, Inc. Method for processing stack gas emissions
US20050026008A1 (en) * 2003-06-05 2005-02-03 Solar Reactor Technologies Inc. Method for processing stack gas emissions
WO2005123285A1 (en) * 2004-06-17 2005-12-29 Sorain Cecchini Ambiente Sca S.P.A. Method and system for the recycling of municipal solid wastes, and exploitation of the wasted solid recovery fuel
US20080006034A1 (en) * 2004-06-17 2008-01-10 Manlio Cerroni Method And System For The Recycling Of Municipal Solid Wastes, And Exploitation Of The Wasted Solid Recovery Fuel

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014186431A1 (en) * 2013-05-17 2014-11-20 Sunpower Technologies Llc Photo-catalytic systems for production of hydrogen
CN106905112A (en) * 2017-03-07 2017-06-30 王亚壮 A kind of method and system of new synthesizing methanol
CN106955715A (en) * 2017-03-09 2017-07-18 盐城复华环保产业开发有限公司 A kind of biomass gasifying hydrogen making catalyst and preparation method thereof
CN106955715B (en) * 2017-03-09 2019-09-10 盐城复华环保产业开发有限公司 A kind of biomass gasifying hydrogen making catalyst and preparation method thereof
EP3593650A3 (en) * 2018-06-19 2020-03-18 Vivere Alcalino S.r.l. Preparations capable of increasing the ph of food by releasing molecular hydrogen
CN108751144A (en) * 2018-07-03 2018-11-06 贵州大学 A kind of technique of ardealite and low product bauxite overfiring-proof coating coproduction acid
CN113617340A (en) * 2021-08-18 2021-11-09 甘肃融万科技有限公司 Color-changeable bactericidal attapulgite-based deodorizing and dehumidifying agent and preparation method thereof
CN114029072A (en) * 2021-12-01 2022-02-11 万华化学集团股份有限公司 Solid super acidic catalyst and method for preparing isooctyl p-methoxycinnamate by using same
CN114029072B (en) * 2021-12-01 2023-07-11 万华化学集团股份有限公司 Solid super acid catalyst and method for preparing isooctyl p-methoxycinnamate by using same

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