Combined dehydrogenation reaction system

Abstract

The present invention relates to a combined dehydrogenation reaction system, which comprises: an acidic aqueous solution tank, an exothermic dehydrogenation reactor, an LOHC tank and an endothermic dehydrogenation reactor, wherein the acidic aqueous solution tank has an acidic aqueous solution; the exothermic dehydrogenation reactor comprises a solid chemical hydride and receives the acidic aqueous solution from the acidic aqueous solution tank, and is used to make the chemical hydride and the acidic aqueous solution undergo an exothermic dehydrogenation reaction to generate hydrogen; the LOHC tank comprises a liquid organic hydrogen carrier (LOHC); the endothermic dehydrogenation reactor receives the liquid organic hydrogen carrier from the LOHC tank, and generates hydrogen by making the liquid organic hydrogen carrier undergo an endothermic dehydrogenation reaction using the heat generated by the exothermic dehydrogenation reactor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0017386, filed on February 8, 2021, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to a combined dehydrogenation reaction system for supplying hydrogen to a fuel cell stack. Background Art

[0004] Due to the depletion of fossil energy and environmental pollution problems, there is an increasing demand for renewable energy and alternative energy, and hydrogen as one of such alternative energy sources is attracting attention.

[0005] Fuel cells and hydrogen combustion devices use hydrogen as a reaction gas, and in order to apply fuel cells and hydrogen combustion devices to vehicles and various electronic products, for example, a stable and continuous hydrogen supply technology is required.

[0006] In order to supply hydrogen to the device using hydrogen, a method of receiving hydrogen from a separately installed hydrogen supply source can be used. In this way, compressed hydrogen or liquefied hydrogen can be used for hydrogen storage.

[0007] An alternative method is to generate hydrogen by reaction of the corresponding materials and supply it to the device using hydrogen after loading the material storing hydrogen into the device using hydrogen. For this method, for example, a method using a liquid organic hydrogen carrier (LOHC), an adsorption method, a desorption / carbon (adsorbent / carbon) method, and chemical hydrogen storage have been proposed.

[0008] However, the dehydrogenation of the liquid organic hydrogen carrier is an endothermic reaction, and therefore requires a heat source to provide the reaction heat. A system is known that generates heat by burning some of the generated hydrogen to provide the heat required for the dehydrogenation reaction of the liquid organic hydrogen carrier.

[0009] However, when a hydrogen burner is used to provide the dehydrogenation heat of a liquid organic hydrogen carrier, compared to conventional compressed hydrogen (CGH 2 ) system, the hydrogen storage efficiency of the dehydrogenation system is reduced by about 40%. In addition, in order to meet the reaction temperature conditions of 200°C or higher, it may take 10 minutes or more to generate hydrogen during the operation of the system.

[0010] Therefore, a system having high thermal efficiency and operational responsiveness is desired compared with conventional methods.

[0011] The above information disclosed in this Background Technology section is only for enhancement of understanding of the background technology of the present application and therefore it may contain information that does not constitute the prior art that is already known in this country to a person skilled in the art. Summary of the invention

[0012] One embodiment provides a combined dehydrogenation reaction system, in which during operation, hydrogen can be stably produced within a few minutes, thereby resulting in excellent operational responsiveness and improved thermal efficiency to ensure high hydrogen storage capacity, and stable thermal treatment and increased hydrogen production rate can be achieved through the combination of the two systems.

[0013] According to the embodiment, the combined dehydrogenation reaction system includes: an acidic aqueous solution tank, an exothermic dehydrogenation reactor, a LOHC tank and an endothermic dehydrogenation reactor, wherein the acidic aqueous solution tank includes an acidic aqueous solution, the exothermic dehydrogenation reactor includes a solid chemical hydride and receives the acidic aqueous solution from the acidic aqueous solution tank for subjecting the chemical hydride and the acidic aqueous solution to an exothermic dehydrogenation reaction to produce hydrogen, the LOHC tank includes a liquid organic hydrogen carrier (LOHC), the endothermic dehydrogenation reactor receives the liquid organic hydrogen carrier from the LOHC tank and produces hydrogen by subjecting the liquid organic hydrogen carrier to an endothermic dehydrogenation reaction using heat generated by the exothermic dehydrogenation reactor.

[0014] Chemical hydrides may include sodium borohydride (NaBH 4 ), lithium borohydride (LiBH 4 ), potassium borohydride (KBH 4 ), ammonium borohydride (NH 4 BH 4 ), borane ammonia (NH 3 BH 3 ), tetramethylammonium borohydride ((CH 3 ) 4 NH 4 BH 4 ), sodium aluminum hydride (NaAlH 4 ), lithium aluminum hydride (LiAlH 4 ), potassium aluminum hydride (KAlH 4 ), calcium borohydride (Ca(BH 4 ) 2 ), magnesium borohydride (Mg(BH 4 ) 2 ), sodium gallium hydride (NaGaH 4 ), LiGaH 4 ), potassium gallium hydride (KGaH 4 ), lithium hydride (LiH), calcium hydride (CaH 2 ), magnesium hydride (MgH 2 ) or a mixture thereof.

[0015] The acid may include sulfuric acid, nitric acid, phosphoric acid, hydrochloric acid, boric acid, a heteropoly acid, acetic acid, formic acid, malic acid, citric acid, tartaric acid, ascorbic acid, lactic acid, oxalic acid, succinic acid, taurine, or mixtures thereof.

[0016] In the exothermic dehydrogenation reactor, the exothermic dehydrogenation reaction may be performed by reacting 1 mole of hydrogen atoms of the chemical hydride with an acid and water in a molar ratio of 0.5 to 2.

[0017] In the exothermic dehydrogenation reactor, the temperature of the exothermic dehydrogenation reaction may be 10° C. to 400° C., and the pressure may be 1 bar to 100 bar.

[0018] The liquid organic hydrogen carrier may include decalin (decalin), tetralin (1,2,3,4-tetralin), cyclohexane, dicyclohexyl, methylcyclohexane (MCH), N-ethylcarbazole (NEC), perhydro-N-ethylcarbazole, dibenzyltoluene (DBT), a mixture of biphenyl and biphenylmethane (BPDM), or a combination thereof.

[0019] In the endothermic dehydrogenation reactor, the endothermic dehydrogenation reaction can be carried out in the presence of a catalyst, wherein the catalyst comprises platinum / alumina (Pt / Al 2 O 3 ), platinum / carbon (Pt / C), palladium / alumina (Pd / Al 2 O 3 ), palladium / carbon (Pd / C), platinum-tin / alumina (Pt-Sn / Al 2 O 3 ), platinum-palladium / alumina (Pt-Pd / Al 2 O 3 ), platinum-rhodium / alumina (Pt-Rh / Al 2 O 3 ), platinum-ruthenium / alumina (Pt-Ru / Al 2 O 3 ), platinum-iridium / alumina (Pt-Ir / Al 2 O 3 ) or a combination thereof.

[0020] The catalyst may contain 0.1 wt % to 5.0 wt % of the noble metal relative to the total catalyst.

[0021] In the endothermic dehydrogenation reactor, the endothermic dehydrogenation reaction may be performed at 150°C to 350°C.

[0022] The combined dehydrogenation reaction system may also include a heat source for providing heat to the endothermic dehydrogenation reactor.

[0023] A fuel cell stack that generates electricity and water by receiving hydrogen and oxygen generated by an exothermic dehydrogenation reactor, an endothermic dehydrogenation reactor, or both an exothermic dehydrogenation reactor and an endothermic dehydrogenation reactor may also be included.

[0024] The endothermic dehydrogenation reactor can also use the heat generated by the fuel cell stack to perform the endothermic dehydrogenation reaction of the liquid organic hydrogen carrier.

[0025] The combined dehydrogenation reaction system may further include a hydrogen separator for separating hydrogen from the reaction product produced by the endothermic dehydrogenation reactor.

[0026] The combined dehydrogenation reaction system may further include a buffer tank for storing hydrogen produced by the exothermic dehydrogenation reactor and the endothermic dehydrogenation reactor.

[0027] The combined dehydrogenation reaction system may further comprise a pressure regulator located between the exothermic dehydrogenation reactor and the buffer tank or a pressure regulator located between the endothermic dehydrogenation reactor and the buffer tank, or both of the pressure regulators.

[0028] The combined dehydrogenation reaction system may further include a pump for supplying the acidic aqueous solution from the acidic aqueous solution tank to the exothermic dehydrogenation reactor, a pump for supplying the liquid organic hydrogen carrier from the LOHC tank to the endothermic dehydrogenation reactor, or both pumps.

[0029] In the combined dehydrogenation reaction system according to the embodiment, hydrogen can be stably generated within a few minutes during operation, resulting in excellent operational responsiveness and improved thermal efficiency to ensure high hydrogen storage capacity, and stable heat treatment and increased hydrogen production rate can be achieved through the combination of the two systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a view schematically showing a combined dehydrogenation reaction system according to an embodiment.

[0031] Figure 2 This is a graph showing the measurement results of the hydrogen storage capacity of the exothermic dehydrogenation reactor of Embodiment 1.

[0032] Figure 3 This is a graph showing the measurement results of the hydrogen storage capacity of the exothermic dehydrogenation reactor of Embodiment 2.

[0033] Figure 4 This is a graph showing the measurement results of the hydrogen storage capacity of the exothermic dehydrogenation reactor of Embodiment 3.

[0034] Figure 5 This is a graph showing the measurement results of the hydrogen storage capacity of the exothermic dehydrogenation reactor of Embodiment 4.

[0035] Figure 6It is a graph showing the measurement results of the reaction starting temperature of the endothermic dehydrogenation reactor of Embodiment 5 changing according to the reaction pressure.

[0036] Figure 7 It is a graph showing the comparison results of the hydrogen storage efficiency of each LOHC type of the combined dehydrogenation reaction system of Embodiment 6.

[0037] Figure 8 It is a graph showing the measurement results of the change in hydrogen conversion rate over time of the combined dehydrogenation reaction system of Embodiment 6. DETAILED DESCRIPTION

[0038] By referring to the following description of the embodiments of the accompanying drawings described later, the advantages, features and aspects described later will become apparent. However, the present application is not limited to the embodiments described herein. Although not specifically limited, all terms including technical terms and scientific terms used herein have the meanings understood by those skilled in the art. These terms have specific meanings and lexical meanings consistent with the relevant technical references and this specification. In other words, these terms cannot be interpreted as having idealized or overly formal meanings. In the following description and claims, unless explicitly described to the contrary, the term "comprise / include" or, for example, "comprises / includes" or "comprising / including" changes should be understood to mean including the elements, but not excluding any other elements.

[0039] Unless otherwise specified, terms in the singular may include plural forms.

[0040] In the drawings, the thickness of layers, films, plates, regions, etc., are exaggerated for clarity. Throughout the specification, the same reference numerals refer to the same elements.

[0041] Figure 1 FIG. 2 is a diagram schematically showing a combined dehydrogenation reaction system according to an embodiment of the present invention. Figure 1 The combined dehydrogenation reaction system is described in detail.

[0042] refer to Figure 1 The combined dehydrogenation reaction system 10 includes an acidic aqueous solution tank 110, an exothermic dehydrogenation reactor 210, a LOHC tank 120, and an endothermic dehydrogenation reactor 220. In other words, the combined dehydrogenation reaction system 10 is a combined system including the exothermic dehydrogenation reactor 210 and the endothermic dehydrogenation reactor 220.

[0043] Acidic aqueous solution tank 110 comprises acidic aqueous solution. Acidic aqueous solution provides proton and water for the hydrolysis reaction of solid chemical hydride, thereby promoting exothermic dehydrogenation reaction. Acid can be inorganic acid (for example, sulfuric acid, nitric acid, phosphoric acid, boric acid or hydrochloric acid), organic acid (for example, heteropoly acid, acetic acid, formic acid, malic acid, citric acid, tartaric acid, ascorbic acid, lactic acid, oxalic acid, succinic acid and taurine) or its mixture, and because molecular weight is small compared with hydrogen ion, so that system weight can be reduced, and formic acid (HCOOH) can be used, because formic acid is safer than hydrochloric acid under high concentration state. In the case of formic acid (which is a weak acid), in one embodiment, under the conditions described in the present application, pH is maintained at about 2, so formic acid can be used relatively safely. In addition, captured carbon dioxide can be obtained by hydrogenation, so it is an important material in terms of recovery / recycling of carbon dioxide. In addition, formate is converted into bicarbonate by dehydrogenation reaction, so that additional hydrogen can be obtained. Acidic aqueous solution tank 110 supplies acidic aqueous solution to exothermic dehydrogenation reactor 210. Between the acidic aqueous solution tank 110 and the exothermic dehydrogenation reactor 210 , a pump 620 for supplying the acidic aqueous solution to the exothermic dehydrogenation reactor 210 may be included.

[0044] The exothermic dehydrogenation reactor 210 contains a solid state chemical hydride.

[0045] For example, the solid chemical hydride may be in the form of any one of powder, granules, beads, microcapsules, and pellets. When the chemical hydride is stored in the form of an aqueous solution (e.g., a chemical hydride having a concentration of about 20%), a large amount of chemical hydride 111 cannot be stored, but when the chemical hydride is stored in a solid state, large-capacity storage can be achieved.

[0046] The chemical hydride may be any compound that can be hydrolyzed to produce hydrogen and a hydrolysis product, for example, it may include NaBH 4 , LiBH 4 KBH 4 NH 4 BH 4 NH 3 BH 3 , (CH 3 ) 4 NH 4 BH 4 、NaAlH 4 、LiAlH 4 , KAlH 4 , Ca(BH 4 ) 2 Mg(BH 4 ) 2 、NaGaH 4 、LiGaH 4 , KGaH4 , LiH, CaH 2 MgH 2 or a mixture thereof, in particular, it may be NaBH 4 .

[0047] In the exothermic dehydrogenation reactor 210, an exothermic dehydrogenation reaction is performed in which hydrogen is produced by a hydrolysis reaction of an acidic aqueous solution with a chemical hydride.

[0048] For example, when the chemical hydride is NaBH 4 When the acid is HCOOH, an exothermic dehydrogenation reaction is carried out according to the following reaction formula 1.

[0049] [Reaction 1]

[0050] NaBH 4 +HCOOH+4H 2 O→HCOONa+H 3 BO 3 +H 2 O+4H 2 →HCO 3 Na+H 3 BO 3 +5H 2

[0051] At this time, in the exothermic dehydrogenation reactor 210, an exothermic dehydrogenation reaction may be performed by reacting 1 mole of hydrogen atoms of the chemical hydride with an acid and water in a molar ratio of 0.5 to 2. If the molar ratio of the acid and water is less than 0.5, the chemical hydride may not react sufficiently, and if it is greater than 2, the system weight and the reactor volume may increase. At the same time, the reaction heat generated by the exothermic dehydrogenation reactor 210 is transferred to the endothermic dehydrogenation reactor 220 and used to drive the dehydrogenation reaction of the liquid organic hydrogen carrier.

[0052] Therefore, since it is not necessary to supply heat to the endothermic dehydrogenation reactor 220 after a portion of the generated hydrogen is combusted to generate heat, thermal efficiency can be improved and a high hydrogen storage capacity can be ensured.

[0053] In addition, when acid and water are used to generate hydrogen from chemical hydrides, water is easily evaporated (water evaporation temperature: 175° C. at 10 bar, 260° C. at 50 bar) due to an exothermic reaction, and the amount of hydrogen generated (i.e., hydrogen storage capacity) may be reduced. However, by transferring the reaction heat to the endothermic dehydrogenation reactor 220, the evaporation of water can be prevented, and the amount of hydrogen generated can be maximized by reducing the amount of water used.

[0054] There is no particular limitation on the method of transferring the reaction heat of the exothermic dehydrogenation reactor 210 to the endothermic dehydrogenation reactor 220. For example, a method of directly transferring heat by bringing the exothermic dehydrogenation reactor 210 into contact with the endothermic dehydrogenation reactor 220, a method of indirectly transferring heat by generating steam or a heat source using the reaction heat generated by the exothermic dehydrogenation reactor 210 and then transferring it to the endothermic dehydrogenation reactor 220, or a method of indirectly transferring heat by providing a heat exchanger between the exothermic dehydrogenation reactor 210 and the endothermic dehydrogenation reactor 220 may be used.

[0055] On the other hand, the exothermic dehydrogenation reaction can be carried out under conditions of high temperature and high pressure.

[0056] In this way, hydrogen can be stably generated within a few minutes (for example, within 2 minutes from the start of system operation), so the operation responsiveness is excellent, and the amount of hydrogen generated is maximized due to the prevention of water evaporation and the reduction of water consumption. In addition, CO can be suppressed by the pressurized operation of the exothermic dehydrogenation reactor 210. 2 The production of.

[0057] In addition, if the hydrogen contains an excess of water after the dehydrogenation reaction, a separate gas-liquid separator may be used, but this may increase the volume and weight of the entire system, resulting in a decrease in hydrogen storage capacity. However, by operating the exothermic dehydrogenation reactor 210 at a high temperature and high pressure, the hydrogen storage capacity can be increased and the system cost and weight can be reduced.

[0058] For example, the temperature of the exothermic dehydrogenation reaction may be 10° C. to 400° C., or 100° C. to 250° C. When the temperature of the exothermic dehydrogenation reaction is lower than 10° C., the acid or acidic aqueous solution may condense or separate, and when the temperature is higher than 400° C., carbon monoxide may be generated and secondary reactions may increase.

[0059] The pressure of the exothermic dehydrogenation reaction may be 1 bar to 100 bar, or 5 bar to 50 bar. If the pressure of the exothermic dehydrogenation reaction is less than 1 bar, a pressure reducing pump may be used, which may increase the weight of the system. If the pressure is greater than 100 bar, the exothermic dehydrogenation reaction is inhibited, and the weight and volume of the high temperature / high pressure vessel may increase.

[0060] The hydrogen generation rate in the exothermic dehydrogenation reactor 210 can be controlled by changing the injection rate of the acidic aqueous solution or by fixing the injection rate and changing the injection time (valve opening time). Therefore, since a separate pump is not required, the cost and weight of the system can be reduced.

[0061] The LOHC tank 120 contains a liquid organic hydrogen carrier (LOHC).

[0062] The liquid organic hydrogen carrier may be a monocyclic hydrogenated aromatic compound, a bicyclic hydrogenated aromatic compound or a tricyclic hydrogenated aromatic compound, for example, it may include decalin (decahydronaphthalene), tetralin (1,2,3,4-tetrahydronaphthalene), cyclohexane, dicyclohexyl, methylcyclohexane (MCH), N-ethylcarbazole (NEC), perhydro-N-ethylcarbazole, dibenzyltoluene (DBT), a mixture of biphenyl and biphenylmethane (BPDM), or a combination thereof.

[0063] The LOHC tank 120 supplies the liquid organic hydrogen carrier to the endothermic dehydrogenation reactor 220. Between the LOHC tank 120 and the endothermic dehydrogenation reactor 220, a pump 610 for supplying the liquid organic hydrogen carrier to the endothermic dehydrogenation reactor 220 may be included.

[0064] The endothermic dehydrogenation reactor 220 generates hydrogen through an endothermic dehydrogenation reaction of a liquid organic hydrogen carrier.

[0065] For example, in the endothermic dehydrogenation reaction, hydrogen atoms on the periphery of the aliphatic ring of the hydrogenated LOHC are abstracted, and thus the aliphatic ring is converted into an aromatic ring. The reaction temperature ranges from 150°C to 350°C.

[0066] As described above, the endothermic dehydrogenation reactor 220 receives the reaction heat generated by the exothermic dehydrogenation reactor 210 and causes the liquid organic hydrogen carrier to undergo an endothermic dehydrogenation reaction. Therefore, since it is not necessary to provide heat to the endothermic dehydrogenation reactor 220 after a portion of the generated hydrogen is burned, thermal efficiency can be improved and a high hydrogen storage capacity can be ensured.

[0067] The endothermic dehydrogenation reaction may be performed in the presence of a catalyst, and the endothermic dehydrogenation reactor 220 may include a catalyst. For example, the catalyst for the endothermic dehydrogenation reaction may include Pt / Al 2 O 3 、Pt / C、Pd / Al 2 O 3 、Pd / C、Pt-Sn / Al 2 O 3 、Pt-Pd / Al 2 O 3 、Pt-Rh / Al 2 O 3 、Pt-Ru / Al 2 O 3 、Pt-Ir / Al 2 O 3 or a combination thereof.

[0068] The catalyst may contain 0.1 wt % to 5.0 wt %, such as 0.3 wt % to 3.0 wt %, of a noble metal such as Pt, Pd, Rh, Ru, and Ir, relative to the entire catalyst. If the content of the noble metal in the catalyst is less than 0.1 wt %, the catalytic reaction rate may be too slow, and if it is greater than 5.0 wt %, it may be difficult to commercialize in terms of its cost.

[0069] If necessary, the combined dehydrogenation reaction system 10 may further include a separate heat source 230 for providing heat to the endothermic dehydrogenation reactor 220. When the heat transferred from the exothermic dehydrogenation reactor 210 is insufficient for the endothermic dehydrogenation reaction, the separate heat source 230 may provide insufficient reaction energy.

[0070] The type of the heat source 230 is not particularly limited, and as an example, a hydrogen burner that generates heat by partially burning generated hydrogen, or an electric heater composed of a heating wire, etc. may be used.

[0071] Meanwhile, when the endothermic dehydrogenation reaction in the endothermic dehydrogenation reactor 220 is a gas phase reaction, the combined dehydrogenation reaction system 10 may further include a hydrogen separator 300 for separating hydrogen and dehydrogenated LOHC from the reaction product generated in the endothermic dehydrogenation reactor 220 .

[0072] For example, when LOHC reacts in a gaseous state (such as MCH, BPDM, etc.), LOHC may pass through the hydrogen separator 300 to separate the generated hydrogen and dehydrogenated LOHC, and when LOHC reacts in a liquid state (such as NEC or DBT), LOHC may not pass through the hydrogen separator 300.

[0073] The hydrogen generated by the exothermic dehydrogenation reactor 210 and the endothermic dehydrogenation reactor 220 is transferred to the buffer tank 400. The buffer tank 400 receives and stores a certain amount of hydrogen.

[0074] If necessary, hydrogen can be compressed to 1 bar to 200 bar by pressure regulators 710 and 720 and stored in the buffer tank 400. To this end, the combined dehydrogenation reaction system 10 may include a pressure regulator 720 located between the exothermic dehydrogenation reactor 210 and the buffer tank 400, or may include a pressure regulator 710 located between the endothermic dehydrogenation reactor 220 and the buffer tank 400.

[0075] The fuel cell stack 500 is located downstream of the buffer tank 400 to receive hydrogen from the buffer tank 400. For example, the hydrogen may be received from the buffer tank 400 through an inlet hole (eg, a valve).

[0076] The fuel cell stack 500 generates water through the reaction of supplied hydrogen and oxygen, and simultaneously generates electric energy. The water generated by the fuel cell stack 500 is discharged through a discharge device (eg, a valve).

[0077] At this time, the water exhausted from the fuel cell stack 500 is recycled to the acidic aqueous solution tank 110, the exothermic dehydrogenation reactor 210, a separate water tank, or all of these devices, thereby increasing the hydrogen storage capacity based on the material.

[0078] In addition, the heat generated by the fuel cell stack 500 is transferred to the endothermic dehydrogenation reactor 220 as needed, so that insufficient heat for the endothermic dehydrogenation reaction can be compensated.

[0079] The fuel cell stack 500 can be any device capable of converting hydrogen into usable electrical energy, such as a proton exchange membrane fuel cell (PEMFC), an alkaline fuel cell (AFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), or a solid oxide fuel cell (SOFC), etc., but the present application is not limited thereto.

[0080] For example, the electric energy generated by the fuel cell stack 500 can be passed through a power converter, such as a DC converter, an inverter, or a charge controller. The power converter outputs a portion of the electric energy to the electrical load through a load interconnector, and another portion of the electric energy can be delivered back to the energy storage device through a recharging interconnector. The remaining portion of the electric energy can be used to power the control unit.

[0081] If desired, the combined dehydrogenation reaction system 10 may also include additional pumps, filters, or both, and may further include control equipment to control the operation of the combined dehydrogenation reaction system 10 .

[0082] As described above, the acidic aqueous solution of the acidic aqueous solution tank 110 may be supplied to the exothermic dehydrogenation reactor 210, or the liquid organic hydrogen carrier of the LOHC tank 120 may be supplied to the endothermic dehydrogenation reactor 220 using the pumps 610 and 620. In addition, an additional pump may be included to supply hydrogen generated in the exothermic dehydrogenation reactor 210 and the endothermic dehydrogenation reactor 220 to the buffer tank 400 or the fuel cell stack 500.

[0083] The filter can substantially remove unwanted particles contained in the hydrogen by filtering the generated hydrogen. The filter can be located between the exothermic dehydrogenation reactor 210, the endothermic dehydrogenation reactor 220, the hydrogen separator 300, the buffer tank 400, and the fuel cell stack 500, and in particular between the buffer tank 400 and the fuel cell stack 500.

[0084] The control device may be arranged to control the operation of a plurality of pumps, regulators, needle valves, check valves, ball valves and multi-way valves via control lines.

[0085] Therefore, since the combined dehydrogenation reaction system 10 can stably generate hydrogen within 2 minutes after the system operation starts through the high temperature and high pressure reaction of the exothermic dehydrogenation reactor 210, it has excellent responsiveness. The thermal efficiency can be maximized by using the heat H generated by the exothermic dehydrogenation reactor 210 as a heat source for the endothermic dehydrogenation reaction of the endothermic dehydrogenation reactor 220. Therefore, through the parallel hydrogen production of the exothermic dehydrogenation reactor 210 and the endothermic dehydrogenation reactor 220, high hydrogen storage capacity, stable heat treatment and improved hydrogen production rate can be achieved.

[0086] The specific embodiments of the present application are shown below. However, the embodiments described below are only intended to specifically illustrate or describe the present application, and do not limit the scope of the present application.

[0087] (Exothermic dehydrogenation reaction evaluation method)

[0088] The solid chemical hydride is loaded into the high temperature and high pressure exothermic dehydrogenation reactor 210. The acidic aqueous solution mixed in a predetermined molar ratio is injected using a syringe or an HPLC pump. At this time, the injection speed can be adjusted from 0.01 mL / min to 20 mL / min, and it can be changed according to the amount of the chemical hydride.

[0089] The pressure and temperature are measured and maintained by valve control and cooling. In some cases, H2 can be injected first. 2 O, and then the acid can be injected.

[0090] The hydrogen conversion rate can be calculated by the following Equation 1, and the flow rate and purity are measured using a mass flow meter and a gas chromatograph (GC).

[0091] [Equation 1]

[0092] Hydrogen conversion rate = (amount of hydrogen discharged from the reactor by mass flow meter + (pressure at room temperature after reaction) × (reactor volume)) / (theoretical amount of hydrogen produced)

[0093] (Implementation 1)

[0094] By using an exothermic dehydrogenation reactor, at room temperature and atmospheric pressure, the chemical hydride NaBH 4 and acid HCOOH to undergo dehydrogenation reaction. At this time, NaBH 4 :αHCOOH:βH 2 The hydrogen storage capacity (H) is measured by the reaction molar ratio of O (where 0≤α≤1, 3≤β≤4 and α+β=4). 2 Storage capacity, weight %). The results are shown in Figure 2 middle.

[0095] refer to Figure 2 In Embodiment 1, the reaction is carried out at room temperature / atmospheric conditions according to the following reaction formula 2, HCOOH and H 2 The total reaction mole of O was maintained at 4 (for example, to minimize the amount of water used), and as a result of the reaction, it was confirmed that hydrogen was generated under the conditions of 0.25 mol to 1 mol of HCOOH, and particularly, hydrogen close to the theoretical storage amount was generated at 0.5 mol.

[0096] [Reaction 2]

[0097]

[0098] (Implementation 2)

[0099] By using an exothermic dehydrogenation reactor, NaBH 4 :αHCOOH:βH 2 The reaction molar ratio of O was fixed at α=0.5 and β=3.5, and the hydrogen storage capacity was measured while changing the temperature from 25°C to 300°C and the pressure from 1 bar to 50 bar. The results are shown in Figure 3 middle.

[0100] refer to Figure 3 , the reaction temperature and pressure were increased to prevent water evaporation, and the same amount of hydrogen production as the theoretical value was obtained, and as a result of determining the optimal reaction conditions, it was confirmed that the hydrogen storage capacity was 6 wt % or more at a temperature of 100° C. to 250° C. and a pressure of 5 bar to 50 bar, and in particular, a conversion rate of 97% was achieved in the range of 100° C. to 250° C. and 30 bar to 50 bar.

[0101] (Implementation 3)

[0102] By using an exothermic dehydrogenation reactor at 180 °C and 30 bar, NaBH 4 :αHCOOH:βH 2 The reaction molar ratio of O was changed to α = 0.5 and 2 ≤ β ≤ 4, and the hydrogen storage capacity was measured. The results are shown in Figure 4 middle.

[0103] refer to Figure 4 As a result of determining the conditions for minimizing the amount of water used under high temperature / high pressure conditions, when HCOOH is 0.5 mol, H 2 O can be reduced to 2 mol, resulting in a hydrogen storage capacity of 8.3 wt% in theory and 7.0 wt% in experiments (room temperature / atmospheric pressure conditions: 5.5 wt%).

[0104] (Implementation 4)

[0105] By using an exothermic dehydrogenation reactor at 180 °C and 30 bar, NaBH 4 :αHCOOH:βH 2 The reaction molar ratio of O was changed to 0≤α≤0.7, 1.8≤β≤2.5 and α+β=2.5, and the hydrogen storage capacity was measured. The results are shown in Figure 5 middle.

[0106] refer to Figure 5 In order to minimize water consumption, HCOOH and H 2 After the total reaction molar ratio of O was fixed to 2.5, the amount of hydrogen generated according to the HCOOH molar ratio was measured, and it was confirmed that the hydrogen storage capacity was 6 wt % or more in the range of 0.3 mol to 0.5 mol of HCOOH.

[0107] (Implementation 5)

[0108] In order to determine the reaction temperature range of the endothermic dehydrogenation reactor, methylcyclohexane (MCH) was dehydrogenated to calculate the reaction starting temperature based on the reaction pressure. The results are shown in Figure 6 middle.

[0109] refer to Figure 6 It can be seen that the lower the reaction pressure, the lower the reaction starting temperature of methylcyclohexane. It is expected that other types of LOHC also have the effect of reducing the reaction temperature due to reduced pressure. Due to this decompression effect, it is expected that the reaction temperature of LOHC is generally 250°C or lower.

[0110] (Implementation 6)

[0111] Figure 7 To show the use of a hydrogen combustion device (hydrogen burner) to provide heat to the endothermic dehydrogenation reaction of the endothermic dehydrogenation reactor (case 1, LOHC only) and the NaBH system consisting of an exothermic dehydrogenation reactor and an endothermic dehydrogenation reactor but without a separate heat source 4 - Graph showing the comparison results of the hydrogen storage efficiency of various LOHC types for a LOHC combination system (Case 2, combination).

[0112] exist Figure 7 In the figure, as LOHC, CGH2 represents a conventional compressed gas (compressed hydrogen) system, MCH represents methylcyclohexane, DBT represents dibenzyltoluene, NEC represents N-ethylcarbazole, Decalin represents decalin, and BPDM represents a mixture of biphenyl and biphenylmethane.

[0113] refer to Figure 7 , when using an internal heat source (LOHC only), the hydrogen storage capacity does not reach the level of conventional compressed gas CGH2, while in NaBH 4In the case of the -LOHC combined system (combination), it was confirmed that the hydrogen storage capacity could be increased to a level of 6.8 wt %, while the hydrogen storage efficiency was increased to more than 93%.

[0114] Figure 8 The present invention shows the case 1 using a hydrogen combustion device (hydrogen burner) and the case 2 using a NaBH2O3 reactor composed of an exothermic dehydrogenation reactor and an endothermic dehydrogenation reactor but without a separate heat source. 4 - Variation of hydrogen conversion with time when 1 kg of hydrogen is produced in case 2 of the LOHC combined system (combined).

[0115] refer to Figure 8 In the case of the conventional LOHC system (LOHC only), in one embodiment, hydrogen generation starts about 12 minutes after the temperature required for the reaction (e.g., 300° C.) is reached, while in the case of the combined system (combined), it can be determined that hydrogen can be generated quickly because the pressure can be increased to more than 30 bar within 2 minutes. In addition, since hydrogen generation starts in the endothermic dehydrogenation reactor that is sufficiently heated by the reaction heat generated in the exothermic dehydrogenation reactor, it can be determined that hydrogen is generated simultaneously in the two reactors, thereby observing an increase in the hydrogen generation rate.

[0116] As described above, the combined dehydrogenation reaction system according to the embodiment can generate hydrogen without a separate heat source by combining the exothermic dehydrogenation reactor and the endothermic dehydrogenation reactor, thereby improving the thermal efficiency of the endothermic dehydrogenation reactor.

[0117] It has been determined that the combined dehydrogenation reaction system has excellent operational responsiveness and hydrogen production rate, and has improved hydrogen storage capacity due to improved thermal efficiency. Specifically, compared to a separate endothermic dehydrogenation reactor system, in one embodiment, it was determined that the combined dehydrogenation reaction system improves hydrogen storage efficiency by about 40% by removing a separate heat source, and substantially meets the DOE commercial standard of 6.5 weight %.

[0118] In addition, compared with a separate endothermic dehydrogenation reactor system (which requires more than 10 minutes from system start-up to hydrogen production), it was determined that the combined dehydrogenation reaction system can quickly and stably produce hydrogen within 2 minutes through the low reaction temperature conditions and rapid pressure increase technology of the exothermic dehydrogenation reactor.

[0119] When the endothermic dehydrogenation reactor is sufficiently heated by the reaction heat of the exothermic dehydrogenation reactor, hydrogen can be generated from both the exothermic dehydrogenation reactor and the endothermic dehydrogenation reactor, thereby contributing to an increase in the hydrogen generation rate of the combined dehydrogenation reaction system. The combined dehydrogenation reaction system is expected to make an important contribution to the commercially available single endothermic dehydrogenation reactor system due to its high hydrogen storage capacity, fast operation responsiveness and hydrogen generation rate.

[0120] While the present application has been described in connection with what are presently considered to be practical embodiments, it is to be understood that the application is not limited to the disclosed embodiments. On the contrary, the present application is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0121] Description of Reference Numerals

[0122] 10: Combined dehydrogenation reaction system

[0123] 110: Acidic aqueous solution tank

[0124] 120: LOHC tank

[0125] 210: Exothermic dehydrogenation reactor

[0126] 220: Endothermic dehydrogenation reactor

[0127] 230: Heat Source

[0128] 300: Hydrogen separator

[0129] 400: Buffer tank

[0130] 500: Fuel cell stack

[0131] 610, 620: Pump

[0132] 710, 720: Pressure regulator

Claims

1. A combined dehydrogenation reaction system, comprising: an acidic aqueous solution tank, the acidic aqueous solution tank containing an acidic aqueous solution; an exothermic dehydrogenation reactor, the exothermic dehydrogenation reactor containing a solid chemical hydride and receiving an acidic aqueous solution from an acidic aqueous solution tank, for causing the chemical hydride and the acidic aqueous solution to undergo an exothermic dehydrogenation reaction to generate hydrogen; a liquid organic hydrogen carrier tank, the liquid organic hydrogen carrier tank containing a liquid organic hydrogen carrier; and an endothermic dehydrogenation reactor, wherein the endothermic dehydrogenation reactor receives the liquid organic hydrogen carrier from the liquid organic hydrogen carrier tank and generates hydrogen by transferring the reaction heat generated by the exothermic dehydrogenation reactor to the endothermic dehydrogenation reactor to cause the liquid organic hydrogen carrier to undergo an endothermic dehydrogenation reaction, wherein the acid comprises formic acid, The exothermic dehydrogenation reaction is carried out by reacting 1 mole of hydrogen atoms of the chemical hydride with an acid and water in a molar ratio of 0.5 to 2.

2. The combined dehydrogenation reaction system according to claim 1, wherein: The chemical hydride includes NaBH4, LiBH4, KBH4, NH4BH4, NH3BH3, (CH3)4NH4BH4, NaAlH4, LiAlH4, KAlH4, Ca(BH4)2, Mg(BH4)2, NaGaH4, LiGaH4, KGaH4, LiH, CaH2, MgH2 or a mixture thereof.

3. The combined dehydrogenation reaction system according to claim 1, wherein: In the exothermic dehydrogenation reactor, the temperature of the exothermic dehydrogenation reaction is 10° C. to 400° C. and the pressure is 1 bar to 100 bar.

4. The combined dehydrogenation reaction system according to claim 1, wherein: The liquid organic hydrogen carrier includes decalin, tetralin, cyclohexane, dicyclohexyl, methylcyclohexane, N-ethylcarbazole, perhydro-N-ethylcarbazole, dibenzyltoluene, a mixture of biphenyl and biphenylmethane, or a combination thereof.

5. The combined dehydrogenation reaction system according to claim 1, wherein: In the endothermic dehydrogenation reactor, the endothermic dehydrogenation reaction is carried out in the presence of a catalyst, wherein the catalyst includes Pt / Al2O3, Pt / C, Pd / Al2O3, Pd / C, Pt-Sn / Al2O3, Pt-Pd / Al2O3, Pt-Rh / Al2O3, Pt-Ru / Al2O3, Pt-Ir / Al2O3 or a combination thereof.

6. The combined dehydrogenation reaction system according to claim 5, wherein: The catalyst contains 0.1 wt% to 5.0 wt% of a noble metal relative to the total catalyst.

7. The combined dehydrogenation reaction system according to claim 1, wherein: In the endothermic dehydrogenation reactor, the endothermic dehydrogenation reaction is carried out at 150°C to 350°C.

8. The combined dehydrogenation reaction system according to claim 1, wherein: The combined dehydrogenation reaction system also includes a heat source that provides heat to the endothermic dehydrogenation reactor.

9. The combined dehydrogenation reaction system according to claim 1, further comprising: A fuel cell stack generates electric energy and water by receiving hydrogen and oxygen generated by an exothermic dehydrogenation reactor, an endothermic dehydrogenation reactor, or both.

10. The combined dehydrogenation reaction system according to claim 9, wherein: The endothermic dehydrogenation reactor also uses the heat generated by the fuel cell stack to perform an endothermic dehydrogenation reaction of the liquid organic hydrogen carrier.

11. The combined dehydrogenation reaction system according to claim 1, wherein: The combined dehydrogenation reaction system further comprises a hydrogen separator for separating hydrogen from the reaction product produced in the endothermic dehydrogenation reactor.

12. The combined dehydrogenation reaction system according to claim 1, wherein: The combined dehydrogenation reaction system further comprises a buffer tank for storing hydrogen generated by the exothermic dehydrogenation reactor and the endothermic dehydrogenation reactor.

13. The combined dehydrogenation reaction system according to claim 1, wherein: The combined dehydrogenation reaction system further comprises a pressure regulator located between the exothermic dehydrogenation reactor and the buffer tank, or a pressure regulator located between the endothermic dehydrogenation reactor and the buffer tank, or comprises two pressure regulators at the same time.

14. The combined dehydrogenation reaction system according to claim 1, wherein: The combined dehydrogenation reaction system further comprises: a pump for supplying an acidic aqueous solution from an acidic aqueous solution tank to an exothermic dehydrogenation reactor; a pump for supplying liquid organic hydrogen carrier from a liquid organic hydrogen carrier tank to the endothermic dehydrogenation reactor; or It also includes a pump for supplying an acidic aqueous solution and a pump for supplying a liquid organic hydrogen carrier.

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