Hydrogen production method and hydrogen production catalyst

Abstract

A hydrogen production method of the present invention comprises: (a) a catalyst preparation step for preparing a hydrogen production catalyst, including crystalline carbon, as a positive catalyst for a hydrogen production reaction based on hydrocarbon pyrolysis; and (b) a hydrogen generation step for generating hydrogen by pyrolyzing hydrocarbon gas on the catalyst prepared in the step (a). The pyrolysis is performed at 900°C or higher. The hydrogen production catalyst of the present invention can be used in the hydrogen production method of the present invention. According to the present invention, hydrogen can be effectively produced and resources can be utilized.

Description

Hydrogen production method and catalyst for hydrogen production

[0001] The present invention relates to a method for producing hydrogen and a catalyst for producing hydrogen, and more particularly, to a method for producing hydrogen that can effectively produce hydrogen and recycle resources, and a catalyst usable in the method.

[0002] Hydrogen can be used as an environmentally friendly fuel, and its production technology is being developed. However, conventional methods for producing hydrogen from fossil fuels (e.g., natural gas steam reforming, coal gasification) have the problem of generating carbon dioxide. To address this issue, technologies for producing hydrogen by decomposing hydrocarbons using catalysts are also being developed. However, these catalyst-based technologies also face the challenge of handling the carbon (byproduct carbon) produced along with hydrogen. To address this issue, a technology has been developed that converts hydrocarbon gas into hydrogen and graphitic carbon using an iron oxide catalyst (see International Patent Publication No. WO 2016 / 154666 A1). However, this method requires a relatively complex process.

[0003] Therefore, there was a need to develop technologies for more efficient hydrogen production. Furthermore, there was a need to develop technologies for more effective resource utilization.

[0004] Meanwhile, technology for producing hydrogen using carbon materials as catalysts is also being developed, but carbon materials such as crystalline carbon are known to have negligibly low catalytic activity (see Catalysis Today 102-103 (2005) 225-233).

[0005] [Prior Art Literature]

[0006] [Patent Document]

[0007] (Patent Document 1) International Patent Publication WO 2016 / 154666 A1, (October 6, 2016), specification

[0008] [Non-patent literature]

[0009] (Non-patent Document 1) Nazim Muradov, Franklyn Smith, Ali T-Raissi, Catalytic activity of carbons for methane decomposition reaction, Catalysis Today 102-103 (2005) 225-233

[0010] One problem that the present invention seeks to solve is to provide a hydrogen production method that can effectively produce hydrogen and utilize resources.

[0011] In addition, another problem that the present invention seeks to solve is to provide a catalyst for hydrogen production that can be used in a hydrogen production method that can effectively produce hydrogen and utilize resources.

[0012] The technical problems of the present invention are not limited to the problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0013] The inventors of the present invention have completed the present invention by conducting research on a catalyst for hydrogen production, which is contrary to the conventional wisdom that crystalline carbon has negligibly low catalytic activity for hydrogen production.

[0014] A hydrogen production method according to one embodiment of the present invention comprises: (A) a catalyst preparation step of preparing a hydrogen production catalyst including crystalline carbon as a positive catalyst for a hydrogen production reaction by hydrocarbon thermal decomposition; and (B) a hydrogen generation step of generating hydrogen by thermal decomposition of hydrocarbon gas over the catalyst prepared in step (A), wherein the thermal decomposition is performed at 900 degrees Celsius or higher.

[0015] In addition, a catalyst for hydrogen production according to one embodiment of the present invention includes crystalline carbon as a positive catalyst for a hydrogen production reaction by hydrocarbon thermal decomposition, wherein the crystalline carbon has a carbon purity of 95% or more, a hydrocarbon conversion rate of 10% or more, and a hydrogen selectivity of 20% or more, and the hydrocarbon conversion rate and the hydrogen selectivity are based on thermal decomposition conditions including a temperature condition of 900 degrees Celsius or more.

[0016] The present invention has the effect of effectively producing hydrogen and utilizing resources.

[0017] Figure 1 is a flowchart for explaining one embodiment of the present invention.

[0018] Figure 2 is a spectrum showing the results of Raman spectrum measurement before formation of deposited carbon in one experimental example of the present invention.

[0019] Figure 3 is a spectrum showing the results of Raman spectrum measurement after formation of deposited carbon in one experimental example of the present invention.

[0020] The advantages and features of the present invention and the methods for achieving them will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the claims. Like reference numerals refer to like elements throughout the specification.

[0021] A hydrogen production method according to one embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a flowchart illustrating one embodiment of the present invention. As illustrated in FIG. 1, the hydrogen production method according to one embodiment of the present invention includes (A) a catalyst preparation step and (B) a hydrogen generation step.

[0022] (A) The catalyst preparation step is a step of preparing a hydrogen production catalyst containing crystalline carbon as a positive catalyst for the hydrogen production reaction by hydrocarbon thermal decomposition.

[0023] As confirmed by the experimental results, crystalline carbon acts as a positive catalyst for the hydrogen production reaction by hydrocarbon pyrolysis, so hydrogen can be produced by hydrocarbon pyrolysis.

[0024] Crystalline carbon may be carbon that is crystalline in its raw state, as well as carbon that has been at least partially crystalline through processing. Such crystalline carbon is not limited to graphite as long as it is crystalline. In addition, the graphite may be one or more selected from natural graphite or artificial graphite. Artificial graphite includes graphite that has optionally undergone a graphitization process, and also includes carbon materials such as graphitized needle coke. In addition, the crystalline carbon may be expressed as a degree of crystallinity by the interplanar spacing of the carbon hexagonal planes. For example, the crystalline carbon may have an interplanar spacing of the carbon hexagonal planes of less than 0.3400 nm (e.g., 0.3354 to 0.3399 nm). The crystalline carbon may preferably have a carbon purity of 95% or more, more preferably a carbon purity of 99% or more. In addition, the crystalline carbon may more preferably have an impurity content of 100 ppm or less.

[0025] To control purity in this way, the crystalline carbon can undergo a purification process, and through primary purification (e.g., flotation, etc.), the carbon purity can be increased to 95% or more, or through secondary purification (e.g., physical purification, chemical purification, and / or thermal purification, etc.), the impurity content can be controlled to 100 ppm or less, or the carbon purity can be controlled to 99% or more.

[0026] In addition, the crystalline carbon may be subjected to a grinding process (e.g., grinding for preferably 10 hours or less under an inert gas, air, oxygen, or a mixed atmosphere thereof) to control the particle size or specific surface area, and may be subjected to a spheroidization process together with or additionally after the grinding process.

[0027] Additionally, the crystalline carbon may be crystalline carbon coated with amorphous carbon.

[0028] Such crystalline carbon can be purchased commercially or manufactured using a well-known method.

[0029] In addition, the catalyst for hydrogen production is not limited as long as it contains crystalline carbon as a positive catalyst for the hydrogen production reaction by hydrocarbon thermal decomposition, and it is of course not excluded that the catalyst for hydrogen production is composed only of crystalline carbon.

[0030] (B) The hydrogen generation step is a step of generating hydrogen by thermally decomposing hydrocarbon gas over a catalyst prepared in step (A).

[0031] The hydrocarbon is not limited as long as it is thermally decomposed by the catalyst, but is preferably methane. Furthermore, the hydrocarbon gas may preferably be a methane-containing gas or natural gas. Thermal decomposition is preferably performed at 900°C or higher, more preferably between 950°C and 1,100°C. Below this range, thermal decomposition may be insufficient, and above this range, the need for catalyst application may diminish.

[0032] In addition, pyrolysis is preferably performed at a gas space velocity of 8000 hr. -1 Below (0hr) -1 Excluding, more preferably 200hr -1 8,000hr -1 ) can be implemented. Exceeding this range (8000hr) -1 There is a concern that thermal decomposition may be insufficient in excess of this range (200 hr) and below this range (200 hr) -1There is concern that the increase in efficiency compared to the catalyst used (below) will not be significant.

[0033] The generated hydrogen can be collected by a known hydrogen collection method.

[0034] In addition, the hydrogen production method according to one embodiment of the present invention may further include a (C) negative electrode material collection step for a lithium ion secondary battery.

[0035] The negative electrode material collection step for lithium-ion secondary batteries is a step for collecting crystalline carbon formed on the surface of carbon generated by pyrolysis in step (B) through vapor deposition, in order to utilize it as a negative electrode material for lithium-ion secondary batteries. In step (B), carbon generated by pyrolysis vapor-deposits on the surface of the crystalline carbon to form deposited carbon, and thus, in step (C), the crystalline carbon with the deposited carbon formed on the surface can be collected for utilization as a negative electrode material for lithium-ion secondary batteries. Collection can be performed by a widely known method, for example, a method of removing foreign substances after pyrolysis is completed and selecting the crystalline carbon with the deposited carbon formed on the surface. As confirmed from the experimental results, the crystalline carbon with the deposited carbon formed on the surface has improved rate characteristics, which are lacking in the crystalline carbon, and thus can be utilized as a superior negative electrode material for lithium-ion secondary batteries. That is, since crystalline carbon can be used as a catalyst in hydrocarbon pyrolysis and then recycled as an anode material for lithium-ion secondary batteries, it can be seen that the present invention is very effective in terms of resource recycling. In addition, according to the present invention, since an anode material for lithium-ion secondary batteries can be obtained by vapor deposition in the process of producing hydrogen by hydrocarbon pyrolysis without a separate heat treatment or coating process, it is possible to manufacture an anode material for lithium-ion secondary batteries more simply. In addition, since the deposited carbon is formed more uniformly on the surface of the crystalline carbon by vapor deposition, it is more stable than the case where carbon is formed unevenly on the surface of the crystalline carbon, and can also exhibit the desired effect both technically and economically. Meanwhile, it was difficult to find a suitable use for by-product carbon generated together with hydrogen during conventional hydrocarbon pyrolysis, and an additional treatment process for recycling may have been required. However, according to the present invention, it can be seen that by-product carbon can be utilized very usefully both technically and economically without an additional treatment process.

[0036] Deposited carbon is formed by vapor deposition of carbon generated by the thermal decomposition of hydrocarbon gas on the surface of crystalline carbon. This vapor deposition carbon is generally amorphous carbon with a plane distance of 0.3400 nm or more between the hexagonal carbon planes, and may be amorphous carbon with a relatively low crystallinity compared to crystalline carbon. As confirmed by the experimental results, the deposited carbon is non-graphitizable carbon (hard carbon) different from crystalline carbon or graphitizable carbon (soft carbon). This is because the crystalline carbon on which the deposited carbon is deposited exhibits improved rate characteristics (power characteristics) that are lacking in crystalline carbon.

[0037] Crystalline carbon with deposited carbon formed on the surface has high-rate properties. High-rate properties may be a capacity retention ratio in which the discharge capacity at 5.0 C-rate is 80% or more of the discharge capacity at 0.2 C-rate when charge and discharge are performed in a half-cell test method. Such discharge capacity may be based on the charge and discharge capacity evaluation of a half-cell formed with a cathode material as the cathode and lithium metal as the counter electrode. Unlike crystalline carbon, the interplanar distance of the carbon hexagonal network of deposited carbon may be 0.3400 nm or more.

[0038] Considering its usability as a negative electrode material, the crystalline carbon may be powdered carbon in the form of powder. This is because, in order to be utilized as a negative electrode material, a powder state suitable for the particle size or specific surface area required for the negative electrode material is desirable. Therefore, when considering its usability as a negative electrode material, the crystalline carbon preferably has an average particle size of 25㎛ or less (excluding the average particle size of 0㎛, more preferably 0.5㎛ to 25㎛). If this range is exceeded, there is a concern that the electrode charging rate may decrease, resulting in a decrease in charge / discharge capacity, and if it is below this range, there is a concern that the internal resistance of the electrode may increase due to the formation of excessive interfaces between particles. In addition, the crystalline carbon may preferably have a specific surface area of ​​30㎡ / g or less (excluding the specific surface area of ​​0㎡ / g, more preferably 3㎡ / g to 30㎡ / g). If this range is exceeded, there is a concern that the initial charge / discharge efficiency may decrease due to the formation of excessive surface SEI (solid electrolyte interface), and if it is below this range, the electrode charging rate may be inhibited due to excessive particle size, and the input / output characteristics (charge / discharge characteristics) may decrease due to the reduction in the reaction area required for lithium ion intercalation and deintercalation. In addition, from the perspective of the catalyst, if this range is exceeded, there is a concern that the methane thermal decomposition efficiency may decrease, and if it is below this range, there are difficulties in handling, such as catalyst installation and filter attachment in the reactor, and there is a concern that plugging may increase during the fluidization reaction.

[0039] In addition, the crystalline carbon formed on the surface of the deposited carbon preferably has an average particle diameter of 30㎛ or less (excluding an average particle diameter of 0㎛, more preferably 0.6㎛ to 30㎛). If this range is exceeded, there is a concern that the charge / discharge capacity may decrease due to excessive surface formation of deposited carbon, and at the same time, the discharge capacity and initial charge / discharge efficiency may decrease due to excessive surface formation of amorphous carbon. If this range is less than this range, there is a concern that the effect of improving the rate characteristics may decrease due to the small amount of surface formation of amorphous deposited carbon.

[0040] In addition, the crystalline carbon formed on the surface of the deposited carbon may have a specific surface area of ​​30 m2 / g or less (excluding a specific surface area of ​​0 m2 / g, preferably 3 m2 / g to 30 m2 / g). If this range is exceeded, there is a concern that the initial charge / discharge efficiency may decrease due to excessive SEI formation, and if this range is lowered, there is a concern that the electrode charging rate may decrease due to excessive particle size, resulting in a decrease in the discharge capacity.

[0041] In addition, with respect to 100 parts by weight of crystalline carbon, the amount of deposited carbon may be preferably 5 to 50 parts by weight (more preferably 5 to 25 parts by weight). Below this range, the amount of amorphous carbon deposited may decrease, which may not significantly contribute to improving the rate characteristics for discharging a large current in a short period of time, and there is a concern that the deposition may not be evenly distributed on the surface of the crystalline carbon. In addition, above this range, there is a concern that the amount of amorphous carbon formed on the surface of the crystalline carbon may be excessive, which may lower the discharge capacity and initial charge / discharge efficiency.

[0042] The hydrogen production method according to one embodiment of the present invention can be implemented using the hydrogen production catalyst according to one embodiment of the present invention. Specifically, the hydrogen production catalyst according to one embodiment of the present invention may be the hydrogen production catalyst mentioned in the hydrogen production method according to one embodiment of the present invention. To avoid unnecessary duplication, in the description of the hydrogen production catalyst according to one embodiment of the present invention, the matters mentioned in the hydrogen production method according to one embodiment of the present invention may not be separately mentioned. However, the matters mentioned in the hydrogen production method according to one embodiment of the present invention and the hydrogen production catalyst according to one embodiment of the present invention are equally applicable to each other unless they are contradictory.

[0043] Specifically, a catalyst for hydrogen production according to one embodiment of the present invention includes crystalline carbon as a positive catalyst for hydrogen production reaction by hydrocarbon pyrolysis, wherein the crystalline carbon has a carbon purity of 95% or more, a hydrocarbon conversion rate of 10% or more, and a hydrogen selectivity of 20% or more, and the hydrocarbon conversion rate and hydrogen selectivity can be calculated under pyrolysis conditions including a temperature condition of 900 degrees Celsius or more. As confirmed by the experimental results, such a catalyst can produce hydrogen more effectively. The temperature condition may preferably be 950 degrees Celsius to 1,100 degrees Celsius. Below this range, there is a concern that pyrolysis may be insufficient, and above this range, there is a concern that the need for catalyst application may decrease. At this time, the pyrolysis condition is preferably a gas space velocity of 8000 hr. -1 Below (0hr) -1 Excluding, more preferably 200hr -1 8,000hr -1 ) can further include the gas space velocity condition. Exceeding this range (8000 hr -1 There is a concern that thermal decomposition may be insufficient in excess of this range (200 hr) and below this range (200 hr) -1There is concern that the efficiency increase compared to the catalyst used may not be significant in the case of (less than) crystalline carbon. In addition, the volume of crystalline carbon is 8000 hr when the gas space velocity of the hydrocarbon-containing gas is -1 Below (0hr) -1 Excluding, more preferably 200hr -1 8,000hr -1 ) can respond.

[0044] In addition, as previously discussed, when considering the usability as a cathode material, it is desirable for the crystalline carbon to have a deposition surface on which the deposited carbon is deposited.

[0045] Hereinafter, with reference to experimental examples and working examples, one embodiment of the present invention will be described in more detail. The reagents used in the experimental examples were of the highest quality commercially available, purchased from Sigma and others.

[0046] <Experimental Example 1> Experiment to confirm the hydrogen production effect of crystalline carbon (natural graphite)

[0047] An experiment was conducted to confirm the hydrogen production effect by applying crystalline carbon (natural graphite) as a catalyst.

[0048] The crystalline carbon (natural graphite) sample was a sieved sample (Korea Mining and Resources Corporation, carbon content 95.7%, specific surface area 2.45 m2 / g, average particle size D50 84 μm) obtained by flotation and primary grinding. Natural graphite was placed in a prepared planetary mill (Retsch, PM200) equipped with a safety lock and a vented lid to allow for gas atmosphere control, and the mixture ratio of inert gas and oxygen was varied while grinding for 1 to 10 hours (see Table 1). Afterwards, particle size classification was performed using standard mesh sieves of 38 μm, 45 μm, 75 μm, 90 μm, and 125 μm.

[0049] Planetary Mill, PM2001×Planetary machine, 100-240V, 50 / 60Hz2×Grinding stations for jars for 125ml with safety closure device and aeration lidMax speed 650rpm

[0050] The classified samples were measured for particle size distribution separately. First, samples with particle sizes of 38 μm or less and larger than 38 μm were separated using a vacuum suction type sieve classifier (Retsch, AS200 Jet) equipped with a 38 μm standard mesh screen. Approximately 50-100 g of natural graphite sample per time was placed on the 38 μm standard mesh screen and maintained under conditions of rotation (nozzle rotation speed 15 rpm) and reduced pressure (industrial vacuum cleaner, GM80) for 1 minute and 30 seconds. After that, natural graphite samples with particle sizes of 38 μm or less were collected into a 500 mL sample bottle (see Table 2).

[0051] Reduced pressure suction type sieve classifier, AS200 Jet1×Air jet machine, 100-240V, 50 / 60Hz1×Cyclone with holder and collecting receptacle, 500mL sample bottle1×Industrial vacuum cleaner GM80, 230V, 50 / 60 Hz1×Test Sieve, ASTM E11, 8"(203mm)x1", stainless stell, with compliance certificate acc. EN 10204 2.1

[0052] The above process was repeated, and the sample remaining on the top of the 38㎛ standard mesh screen (>38㎛) was collected for the next crushing and classified using a 3D vibrating sifter (Retsch, AS200 Control) equipped with each standard mesh screen. The AS200 Control was equipped with a collecting pan, 38㎛, 45㎛, 75㎛, 90㎛, and 125㎛ standard mesh screens in that order. About 100 g of the collected sample exceeding 38㎛ was placed on the top of the 125㎛ standard mesh screen at each time, and classification was performed while maintaining the vibration intensity at 1.3 mm (see Table 3).

[0053] 3D Vibratory Sieve Shaker (AS200 Control)1×Vibratory Sieve Shaker(AS200 Control), 100-240V, 50 / 60Hz1×Clamping Device “Comport” for Test Sieves 200 / 203Φ1×Test Sieve, ISO 3301 / 1, 200x50mm, 38㎛, 45㎛ and 75㎛ and 90㎛ and 125㎛, stainless steel, with compliance certificate acc. EN10240 2.11×Collecting pand, stainless steel, Φ200x50mm

[0054] The sample remaining on the top of the 38㎛ standard mesh sieve (>38㎛) was placed in a planetary mill and ground for 1-10 hours with various mixing ratios of inert gas and oxygen. The average particle size was evaluated through surface area evaluation and particle size analysis. The results of particle size analysis were compared, and samples with smaller particle sizes and smaller specific surface areas were ground using a jet mill (Hosokawa, MICRON JET-MJQ) (see Table 4).

[0055] MICORON JET-MJQ-LABMill Compressed air[Nm 3 / min] : 1Classifier motor [kW] : 1.5Dimensions[mm] : H×W×D=280×480×280

[0056] The average particle size was analyzed using a Particle Size and Shape Analyzer (Model: MICROTRAC, CAMSIZER X2). Using the dynamic image analysis (Dynamic Image Analysis-ISO 13322-2) measurement principle, 5 g of each of the above-mentioned classified samples was injected into the X-jet Module, and if equipment capable of air pressure dispersion was used to disperse any clumped samples, it was measured using a dry method (see Table 5).

[0057] Particle size analyzer (MICROTRAC, CAMSIZER X2) 1xModule "X-Dry" with "X-Jet" plug-in cartridge 1㎛ to 1.5㎜Measuring time: 2 minutesMeasuring principle: Dynamic Digital Image Processing (ISO 13322-2)Measuring speed: >275 images / sec. each with approx. 1.3 MPixel

[0058] The evaluation of hydrocarbon (methane) pyrolysis using natural graphite powder as crystalline carbon with controlled particle size and specific surface area was carried out according to the following procedure. At this time, the specific surface area was measured by the nitrogen BET method according to the known method (AV Neimark, Y. Lin, PI Ravikovitch, M. Thommes, Quenched solid density functional theory and pore size analysis of micro-mesoporous carbons, Carbon 47 (7) (2009) 1617-1628.). Specifically, about 0.1 g of the sample was evacuated and heated at 300 degrees Celsius for 12 hours to remove moisture and impurities, and then cooled to room temperature. The weight of the dried sample was recorded and the sample cell was mounted on the equipment (see Table 6). The nitrogen pressure applied to the sample was sequentially increased from 0 to 1 atm, and the amount of nitrogen adsorbed by the sample was measured as cm3 / g is measured, and the volume of nitrogen adsorbed per 1.0g of sample is obtained. Afterwards, the acquired data is substituted into the BET theory for the nitrogen adsorption amount according to pressure, and the slope and Y-intercept of the graph converted by the BET equation are used to calculate the specific surface area of ​​the sample in units of m2 / g. The nitrogen adsorption amount according to pressure is substituted into the BJH and NLDFT theory equations, respectively, to obtain a pore size distribution graph to confirm the pore size.

[0059] BELSORP-MAX, Microtrac BELAnalysis and Degas Manifold System (independently)- 1×analysis manifold (turbo molecular pump + Oil vacuum pump)- 1×degas manifold (Oil vacuum pump)Sample Port; 3 ports (Simultaneously measurement)- Low pressure measurement - 1 samples- High accuracy measurement - 2 samples- Standard measurement - 3 samplesPressure Sensor ; 7 ea (Standard)- 5×133 kPa (1000 torr); accuracy ±0.25% FS- 1×13.3 kPa (10 torr) ; accuracy ±0.5% R- 1×0.133 kPa (1 torr) ; accuracy ±0.15% R

[0060] The evaluation of catalytic pyrolysis and hydrogen production of methane-containing gas is conducted as follows. A tubular quartz reactor (outer diameter 1.0 in, inner diameter 23 mm) is installed in a heating furnace capable of heating to the pyrolysis temperature under atmospheric pressure (1 atm), and crystalline carbon is installed between the upper and lower filters of the tubular reactor to prevent leakage during the pyrolysis process. The temperature maintenance section (±10℃, 800 mm) of the heating furnace is confirmed and set through a temperature profile before the experiment to set the gas space velocity (GHSV). Nitrogen gas is flowed up to the target heating temperature, and when the target pyrolysis temperature is reached, nitrogen gas (99.99%) and methane gas (99.95%, N35) are switched to flow only methane gas. The gas flow rate is controlled by an MFC (ATOVAC GMC1200) to maintain a constant space velocity. The temperature of the reactor is controlled by the PID (YOKOGAWA UP35A) in the controller. The components of the gas generated after pyrolysis are evaluated using a gas chromatograph equipped with a thermal conductivity detector (TCD), a flame ionization detector (FID), a metanizer, and a mass spectrometer. If the total proportion of unreacted methane and gases other than hydrogen generated after pyrolysis is less than 0.1%, it is ignored, and the hydrocarbon conversion (based on methane) and hydrogen selectivity are evaluated using the following equation.

[0061] [Formula 1]

[0062]

[0063] In Equation 1, CH 4.전환 is the concentration (volume %) of injected methane gas converted to other gases, CH 4,주입 Silver represents the concentration of injected methane gas (volume %), H2 (%) represents the concentration of hydrogen gas (volume %) generated during pyrolysis, and CH4 (%) represents the concentration of methane gas (volume %) remaining after pyrolysis.

[0064] [Formula 2]

[0065]

[0066] In Equation 2, the amount of hydrogen generated and the amount of total generated gas represent the content (volume%) of hydrogen gas in the total pyrolysis gas after pyrolysis and the total amount (volume%) of the total pyrolysis gas, respectively. Here, the total pyrolysis gas includes unreacted methane gas.

[0067] The ratio of the amount of catalyst and the methane-containing gas, which is the target gas for thermal cracking, is based on the weight hourly space velocity or gas hourly space velocity.

[0068] [Formula 3]

[0069]

[0070] In Equation 3, Q feed gas represents the amount of gas injected per hour, and m catalyst represents the catalyst mass.

[0071] [Formula 4]

[0072]

[0073] In Equation 4, Q feed gas represents the amount of gas injected per hour, and V catalyst represents the catalyst volume.

[0074] The efficiency of conversion of hydrocarbons into hydrogen by a catalyst is evaluated through the following process.

[0075] (1) After installing a certain amount of catalyst in the central part of the vertical tube, fix the position by installing filters on the upper and lower parts of the catalyst layer, and take care to prevent leakage of reactants and products during the reaction process after installing the catalyst.

[0076] (2) The temperature of the reaction section including the catalyst is raised to the reaction temperature, and when the temperature stabilizes, injection of methane gas at a certain concentration is started.

[0077] (3) To determine the type and amount of products generated during the thermal decomposition process, a gas chromatograph (GC) equipped with a valve is connected to the rear end of the reactor (product gas outlet) and analyzed at regular time intervals.

[0078] (4) In the product analysis process, GC / MS analysis is first performed for qualitative analysis, and then GC / TCD / Methanizer-FID analysis is additionally performed for accurate quantitative analysis. The operating conditions of GC / MS and GC / TCD / Methanizer-FID applied for analysis are as follows (see Table 7).

[0079] GC(TCD), Agilent 6890NGC(TCD / FID), GC(TCD), Agilent 6890NGC-MS, Agilent 6890N Column Carboxen TM 1010 PLOT FUSED SILICA Capillary Column,LxI.D., Avg. thickness: 30m×0.53mm×30㎛80 / 100 Porapak QL×Avg. thickness: (6ft×1 / 8in×2.1mm SS)19091P-K15 HP-AL / KCL L×Avg. thickness: 50m×0.320mm×8.00㎛)Operating conditionsOven50℃(2min hold)-250℃(3min hold), 20℃ / minTCD: 200℃Inlet: 200℃Oven50℃(1.5min hold)-200℃(1.0min hold), 20℃ / minTCD: 250℃FID: 250℃Inlet: 200℃Methanizer: 375℃Oven40℃(4.8min hold)-50℃(3.0min hold), 2℃ / min,50℃-150℃(10min hold)25℃ / min

[0080] (5) From the analysis results, the result value is calculated using the above formula.

[0081] The methane-containing gas components are as shown in Table 8 below, and the methane conversion rate and hydrogen selectivity by particle size (temperature 950 degrees Celsius, space velocity 400 hr) -1 The standard) is as shown in Table 9 below.

[0082] Methane-containing gas component concentration CH4≥99.95% N2≤130 ppm O2≤30 ppm C2H6≤300 ppm H2≤20 ppm H2O≤20 ppm

[0083] Example particle size (D50) [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -10.5hr1.0hr2.0hr3.0hr4.0hr5.0hr1-1>125(145.25)2.43Methane conversion rate[%]36.6834.9934.2034.0534.0534.0934.68Hydrogen selectivity[%]53.8652.2251.2451.0751.0651.0951.761-2>90,≤125(99.98)2.52Methane conversion rate[%]36. 5934.7133.9133.5933.4333.3434.26 Hydrogen selectivity [%] 52.2950.3749.6449.5449.6249.8250.211-3 >75,≤90 (65.41) 2.46 Methane conversion [%] 35.0733.8233.3733.2333.1233.0833.62 Hydrogen selectivity [%] 51.9150.8350.5350.595 0.6150.6450.851-4>45,≤75(56.67)2.48Methane conversion[%]38.1836.5235.3834.9534.6834.4635.70Hydrogen selectivity[%]55.6054.1052.7352.2952.1051.9853.131-5>38,≤45(35.05)2.44Methane conversion[%]36.9538.9036.9935. 9935.3735.0436.54Hydrogen selectivity [%]55.7558.5156.3555.0854.2653.8455.631-6≤38(25.35)2.44Methane conversion [%]38.1938.2037.4136.9136.6636.5137.31Hydrogen selectivity [%]59.1459.1157.8357.0256.6956.5657.731-7Above Mixed sample of particle size (84.0) 2.45 Methane conversion [%] 41.84 40.00 37.04 35.77 35.00 34.66 37.39 Hydrogen selectivity [%] 59.09 57.31 54.16 52.77 51.93 51.57 54.47 1-8 (D50) 16.5 16.2 Methane conversion [%] 37.48 37.50 36.94 36.54 36.14 35.97 36.78 Hydrogen selectivity [%] 53.16 54.16 53.8 353.54 53.36 53.29 53.58

[0084] As shown in Table 9, it can be seen that hydrocarbons can be effectively thermally decomposed to produce hydrogen using natural graphite (carbon purity of 95% or more).

[0085] Meanwhile, in Table 9, Example 1-8 is a sample prepared by grinding the sample (>38 ㎛) remaining on the top of the 38 ㎛ standard mesh sieve using a jet mill (HOSOKAWA, MICRON JET-MJQ), unlike Examples 1-1 to 1-7. This is because, compared to Examples 1-1 to 1-7, the specific surface area is large (30 m 2 / g or less) also effectively removes hydrocarbons (950 degrees Celsius, 400 hr) -1 It indicates that hydrogen can be produced by thermal decomposition with a methane decomposition rate of 30% or higher and a hydrogen selectivity of 50% or higher.

[0086] Thus, from the catalytic action of natural graphite, which thermally decomposes hydrocarbons to produce hydrogen, we can see that the carbon generated during the thermal decomposition process is deposited on the surface of natural graphite. This is because the carbon generated during the thermal decomposition process is amorphous carbon, deposited on the surface of natural graphite through vapor deposition. This fact can also be confirmed by the experimental results below.

[0087] Raman spectroscopy

[0088] Raman spectroscopy was performed on samples before and after pyrolysis, and it was confirmed that carbon was deposited on the surface of the crystalline carbon. Specifically, the same sample as Example 1-6 was divided into samples before and after pyrolysis, and each sample was used as a Raman spectroscopy. D / I G The values ​​were measured. Raman spectroscopy was performed using an NRS-3200 Laser Raman Spectroscope (JASCO, Japan). Measurements were performed on pelletized samples using a 514.5 nm argon ion laser beam in a nitrogen atmosphere.

[0089] The results are shown in Fig. 2 and Fig. 3. Fig. 2 is a spectrum showing the results of Raman spectrum measurement for a sample before the formation of deposited carbon, and Fig. 3 is a spectrum showing the results of Raman spectrum measurement for a sample after the formation of deposited carbon. As shown in Fig. 2 and Fig. 3, the crystalline carbon before the deposition of deposited carbon is I D / I G The value is 0.1857, and the crystalline carbon deposited after pyrolysis is I D / I G It can be seen that the value is 1.478. In the case of carbon materials, 1580 cm is derived from the graphite structure (sp2 bonding). -1 The peak near 1350 cm (hereinafter abbreviated as G band) and the diamond structure (sp3 bonding) -1 It consists of a peak (hereinafter referred to as D band) near the G band. The D band is also thought to be a peak due to defects in the graphite structure. In the case of amorphous carbon materials, both peaks are expressed relatively widely, and in crystalline carbon with a high degree of graphitization, the D band peak is smaller than the G band peak, whereas in amorphous carbon such as activated carbon or carbon black, the D band peak is expressed large. The intensity ratio of the peaks of the G and D bands (I D / I G ) is used as an indicator of the degree of amorphous carbon (see TANSO 1996 [No.175] 304-313, Raman Spectroscopy of Graphite and Carbon Materials and Its Recent Application, Gen Katagiri). In particular, in the case of Raman spectroscopy, unlike XRD diffraction, which expresses the average structure of the entire carbon material through the transmission of a beam, the surface structure of the carbon material can be expressed and analyzed more sensitively. Therefore, from the results of this experiment, it can be reconfirmed that amorphous carbon is deposited on the surface of crystalline carbon by hydrocarbon pyrolysis.

[0090] <Experimental Example 2> Experiment to confirm the hydrogen production effect of crystalline carbon (carbon purity 99%)

[0091] A thermal decomposition experiment was conducted using natural graphite (Korea Institute of Energy Research) with a carbon purity of 99% as crystalline carbon, in the same manner as Experimental Example 1. The results are shown in Table 10.

[0092] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr2(D50)17.35.8Methane conversion [%]38.1838.337.4937.2136.9836.7937.51Hydrogen selectivity [%]53.8654.9554.3954.2254.254.0954.31

[0093] As shown in Table 10, it can be seen that even natural graphite (carbon purity of 99% or more) can effectively thermally decompose hydrocarbons to produce hydrogen.

[0094] <Experimental Example 3> Experiment to confirm the hydrogen production effect of spheroidal crystalline carbon

[0095] A thermal decomposition experiment was conducted using spheroidized natural graphite (Elbs graphite) as crystalline carbon in the same manner as Experimental Example 1. The results are shown in Table 11.

[0096] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr3(D50)16.32.88Methane conversion [%]36.6834.9934.2034.0534.0534.0934.68Hydrogen selectivity [%]53.8652.2251.2451.0751.0651.0951.76

[0097] As shown in Table 11, it can be seen that hydrocarbons can be effectively thermally decomposed and hydrogen can be produced even by spheroidal crystalline carbon.

[0098] <Experimental Example 4> Experiment to confirm the effect of crystalline carbon hydrogen production using amorphous / spheroidal carbon coating.

[0099] A thermal decomposition experiment was conducted using natural graphite (POSCO Chemical, PAS-C3B) coated with crystalline carbon and amorphous carbon in the same manner as in Experimental Example 1. The results are shown in Table 12.

[0100] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr4(D50)17.35.8Methane conversion [%]37.6037.6037.6437.7637.8437.9037.72Hydrogen selectivity [%]52.2452.2552.1852.1452.1252.1452.18

[0101] As shown in Table 12, natural graphite coated with amorphous carbon after spheroidization can also effectively pyrolyze hydrocarbons to produce hydrogen.

[0102] <Experimental Example 5> Experiment to confirm the hydrogen production effect of crystalline carbon (artificial graphite)

[0103] Using artificial graphite (Showa Denko, SCMG-BH) as the crystalline carbon, a thermal decomposition experiment was conducted in the same manner as Experimental Example 1. The results are shown in Table 13.

[0104] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr5(D50)22.02.5Methane conversion [%]36.2735.935.6735.5335.535.4835.73Hydrogen selectivity [%]53.3653.1152.8952.7552.7152.6952.92

[0105] As shown in Table 13, artificial graphite can also effectively thermally decompose hydrocarbons to produce hydrogen.

[0106] <Experimental Example 6> Experiment to confirm the hydrogen production effect of crystalline carbon (graphitized needle coke)

[0107] A pyrolysis experiment was conducted in the same manner as Experimental Example 1 using needle coke graphitized with crystalline carbon. The results are shown in Table 15. The graphitized needle coke is an artificial graphite with a carbon hexagonal network plane distance of 0.3394 nm, and needle coke (manufactured by JX) having the specifications described in Table 14 was used after graphitization treatment (2800°C, 10 minutes).

[0108] Item Needle coke Moisture content [%] 0.1 Ash [%] <0.1 True density [g / cm3] 2.13 Apparent density [g / cm3] 1.80 Particle size [%] <5 ㎛ 40 Sulfur content [%] 0.4 Nitrogen content [%] 0.4

[0109] Example: Pyrolysis temperature, space velocity, pyrolysis time, average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr6Methane conversion rate [%]43.244.544.344.744.244.344.2Hydrogen selectivity [%]59.960.761.261.361.361.560.1

[0110] As shown in Table 15, graphitized needle coke can also produce hydrogen by thermally decomposing hydrocarbons.

[0111] <Experimental Example 7> Experiment to confirm the effect of specific surface area of ​​crystalline carbon

[0112] A thermal decomposition experiment was conducted in the same manner as Experimental Example 1 using natural graphite (carbon purity 95%, Korea Mining and Resources Corporation) as described in Table 16 as crystalline carbon. The results are shown in Table 16.

[0113] Example Surface area [㎡ / g] Average particle size [D50, ㎛] Methane conversion rate [%], average hydrogen selectivity [%], average reference 7-1350.01.718.4935.82 Temperature: 950℃, Space velocity: 400hr -1Thermal decomposition time: 5hr7-2240.15.021.4038.747-3131.112.426.7240.577-465.635.728.9144.657-529.665.431.6548.567-62.4583.737.0253.80

[0114] As shown in Table 16, as the specific surface area decreases, hydrogen production tends to be more effective, indicating that thermal decomposition occurs more effectively. Furthermore, it can be seen that hydrogen production can be controlled by adjusting the specific surface area.

[0115] <Experimental Example 8> Experiment to confirm the effect according to pyrolysis temperature

[0116] For the same sample as Example 1-6, the thermal decomposition temperature was changed to the temperature described in Table 17, and the thermal decomposition experiment was conducted in the same manner as Experimental Example 1. The results are shown in Table 17.

[0117] Example Temperature [℃] Space velocity thermal decomposition time Average 400 hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr8-1850Methane conversion rate [%]3.953.913.964.084.224.344.08Hydrogen selectivity [%]7.727.637.727.948.218.437.948-2900Methane conversion rate [%]10.3110.6011.0411.9912.9013.1411.66Hydrogen selectivity [%]19.5219.7020.3421.8723.3224 .7321.588-3950Methane conversion [%]38.1938.2037.4136.9136.6636.5137.31Hydrogen selectivity [%]59.1459.1157.8357.0256.6956.5657.738-41000Methane conversion [%]56.8455.9154.7654.4154.3854.4655.13Hydrogen selectivity [%]73.4072.6071.5771.2471.1771.2071.86

[0118] As shown in Table 17, when the pyrolysis temperature is 900 degrees Celsius or higher, the hydrocarbon conversion rate (based on methane) is 10% or higher, and the hydrogen selectivity is 20% or higher. In addition, when the temperature is 950 degrees Celsius or higher, the hydrocarbon conversion rate (based on methane) is 30% or higher, and the hydrogen selectivity is 50% or higher. From these experimental results, it can be seen that when the pyrolysis temperature is preferably 900 degrees Celsius or higher, and more preferably 950 degrees Celsius or higher, pyrolysis occurs more effectively, and hydrogen production is also more effective.

[0119] Therefore, it can be seen that hydrogen can be effectively produced using the method of the present invention. Furthermore, it can be seen that hydrogen can be effectively produced using the catalyst of the present invention.

[0120] <Experimental Example 9> Experiment to verify the effect according to space velocity

[0121] For the same sample as Example 1-6, the space velocity was changed to the value described in Table 18, and a thermal decomposition experiment was conducted in the same manner as Experimental Example 1. The results are shown in Table 18.

[0122] Example space velocity [hr -1] Temperature Pyrolysis Time Average 950℃ 0.5hr 1.0hr 2.0hr 3.0hr 4.0hr 5.0hr 9-1200 Methane Conversion Rate [%] 38.86 37.60 38.95 39.07 38.79 38.42 38.62 Hydrogen Selectivity [%] 51.10 54.38 56.31 56.62 56.48 56.19 55.18 9-2400 Methane Conversion Rate [% ]38.1938.2037.4136.9136.6636.5137.31Hydrogen selectivity[%]59.1459.1157.8357.0256.6956.5657.739-3500Methane conversion[%]33.0632.6932.3932.2332.2632.2932.49Hydrogen selectivity[%]51.7351.6851.5 051.1351.1951.2251.419-42000Methane conversion rate [%] 27.2227.7128.1828.3528.3628.0127.97Hydrogen selectivity [%] 41.3542.8443.8344.2044.4444.1943.489-54000Methane conversion rate [%] 26.4226.1925.6625.542 5.5125.5225.81 Hydrogen selectivity [%] 45.1844.8243.2942.1741.7641.7143.169-68000 Methane conversion [%] 19.4921.8022.9922.1222.3622.4721.87 Hydrogen selectivity [%] 32.9842.9549.2844.0044.9744.4343.10

[0123] As shown in Table 18, 8000hr -1 It shows a methane conversion rate of more than 20% at a space velocity of 500 hr. -1 It can be seen that a more significant methane conversion rate of over 30% is achieved at a space velocity of . Thus, it can be seen that hydrogen production can be controlled by controlling the space velocity.

[0124] <Experimental Example 10> Cathode Material Performance Evaluation Experiment

[0125] From the above experimental results, it can be seen that hydrogen production can be controlled by adjusting the pyrolysis time, space velocity, and pyrolysis temperature. Furthermore, by controlling hydrogen production, the amount of carbon deposition can also be controlled. Therefore, by controlling the pyrolysis time, space velocity, and pyrolysis temperature, various cathode materials with different amounts of carbon deposition were manufactured, and cathodes containing the cathode materials and secondary batteries (in the form of a half-cell) containing the cathodes were manufactured, and performance evaluation experiments were conducted.

[0126] Specifically, for the same sample as Example 1-6, pyrolysis was performed under the conditions described in Tables 19 and 20, but the pyrolysis experiment was conducted in the same manner as Experimental Example 1. At this time, the amount of deposited carbon was controlled by controlling the pyrolysis time, space velocity, and pyrolysis temperature. The deposited carbon obtained as a result of the pyrolysis experiment was collected to utilize the crystalline carbon formed on the surface as an anode material for lithium-ion secondary batteries. The amount of deposited carbon deposited on the collected crystalline carbon is as described in Tables 19 and 20. At this time, the amount of deposited carbon was calculated as a value measured by a weighing method that measures the weight of the sample before and after deposition. Specifically, the weight before and after deposition was measured using a precision balance (METTLER TLEDO, ME204) immediately after storing the sample for 2 hours under constant temperature and humidity conditions (25 degrees Celsius, 60% relative humidity). The deposition amount was expressed as a percentage by dividing the weight increase (the weight after deposition minus the weight before deposition) by the weight before deposition.

[0127] For the lithium-ion secondary battery negative electrode material collected in this manner, a half-cell of the lithium-ion secondary battery type was manufactured through the following process, and the performance of the negative electrode material, such as discharge capacity, initial efficiency, and rate characteristics, was evaluated.

[0128] O Preparation of slurry;

[0129] For 100 parts by weight of crystalline carbon having deposited carbon formed on the surface, 10 parts by weight of carboxymethyl cellulose (CMC) aqueous solution as a thickener was added in an appropriate amount and stirred and mixed for 30 minutes, and then 10 parts by weight of styrene-butadiene rubber (SBR) aqueous solution as a binder was added in an appropriate amount and stirred and mixed for 5 minutes to produce a negative electrode composite paste.

[0130] Fabrication of O working electrode;

[0131] The obtained negative electrode composite paste was applied onto a copper foil (current collector) having a thickness of 18 μm and heated at 130°C in a vacuum to completely volatilize the solvent. The obtained electrode sheet was rolled with a roller press to have an electrode thickness of approximately 100 μm and a density of approximately 1.5 g / cc, and then punched with a punch to obtain a working electrode.

[0132] O Fabrication of counter electrode;

[0133] In an inert atmosphere, a counter electrode was obtained by punching a lithium metal foil and imprinting it on a nickel mesh (current collector).

[0134] O Fabrication of evaluation batteries;

[0135] Using the above-mentioned working electrode and counter electrode, a coin-type (2023 type) battery was assembled as an evaluation battery under an inert atmosphere. The electrolyte was 1 mol / dm 3 A 1:1 mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) containing lithium salt LiPF6 was used. Charging was performed at a current density of 30 mA / cm. 2 , after constant current charging to a terminal voltage of 0.003 V, the lower limit current is 0.03 mA / cm 2 Maintain the constant potential until the discharge reaches a current density of 350 mA / cm. 2The rate was set to 1C, and after the above charging, constant current discharge was performed up to a potential of 1.5 V at rate rates of 0.2C, 0.5C, 1.0C, 2.0C, and 5.0C for 5 cycles each, and after each 5 cycle of charge / discharge at the above rates, a discharge of 0.2C was performed again to measure the discharge capacity, initial efficiency, and rate characteristics. Here, the rate characteristics were evaluated by dividing the discharge capacity measured at 5.0C by the discharge capacity measured at 0.2C and then converting it to a percentage (%). The results are shown in Tables 19 to 20. Table 19 shows the experimental results evaluating the charge / discharge capacity and initial efficiency among the negative electrode material performance evaluations. Table 20 shows the experimental results evaluating rate characteristics during the performance evaluation of cathode materials, and the rate characteristics are expressed as capacity retention ratio (the discharge capacity measured at 5.0 C divided by the discharge capacity measured at 0.2 C, then converted to a percentage (%)). At this time, a capacity retention ratio of 80% or higher was evaluated as a high-rate characteristic.

[0136] Methane pyrolysis time (950℃, 500hr) -1 ) Deposition amount (Coating amount compared to initial catalyst, %) Charge capacity [mAh / g] Discharge capacity [mAh / g] Initial efficiency (1st cycle coulombic efficiency) [%] Comparative example 1-0 398.0 35 1.18 8.2 Example 10-10.1 hours 5405.5 362.78 9.4 Example 10-20.2 hours 10385.4 353.39 1.7 Example 10-30.5 hours 16396.9 355.6 89.6 Example 10-41.5 hours 25395.1 366.99 2.9 Example 10-53.0 hours 35364.23 22.78 8.6 Example 10-65.0 hours 50358.1321.189.7 Example 10-720.0 hours 150312.7269.786.2 Example 10-820.0 hours Deposited sample graphitized 308.2266.486.4

[0137] As shown in Table 19, it can be seen that the crystalline carbon with the deposited carbon formed on the surface has excellent charge / discharge capacity and initial efficiency. In particular, when 5 to 50 parts by weight of the deposited carbon is deposited for 100 parts by weight of the crystalline carbon, it can be seen that the initial efficiency increases significantly compared to the case where the deposited carbon does not exist. In addition, since there is no significant difference when the deposited sample with a methane pyrolysis time of 20 hours is subjected to graphitization treatment (2800℃, 10 minutes of heat treatment) compared to the case where the graphitization treatment was not performed, it can be seen that the deposited carbon corresponds to non-graphitizable carbon.

[0138] Methane pyrolysis time (950℃, 500hr) -1 ) Deposition amount (coating amount compared to initial catalyst, %)Current density 0.2CCurrent density 5.0CCapacity retention rate [%]Discharge capacity at 5 cyclesDischarge capacity at 25 cyclesComparative example 1-0360.1227.663.2%Example 10-10.1 hours5369.9299.680.1%Example 10-20.2 hours10359.9296.082.2%Example 10-30.5 hours16361.9307.084.8%Example 10-41.5 hours25360.5317.688.1%Example 10-53.0 hours35330.0315.095.5%Example 10-65.0 hours 50323.7293.290.6% Example 10-720.0 hours 150279.1260.095.1%

[0139] As shown in Table 20, it can be seen that the crystalline carbon having the deposited carbon formed on the surface has excellent rate characteristics. In particular, when 5 to 50 parts by weight of the deposited carbon are deposited based on 100 parts by weight of the crystalline carbon, it can be seen that the rate characteristics, that is, the power characteristics, significantly increase while maintaining the discharge capacity and the initial charge / discharge efficiency compared to the case where the deposited carbon does not exist. In addition, when 5 to 25 parts by weight of the deposited carbon are deposited based on 100 parts by weight of the crystalline carbon, it can be seen that the discharge capacity, the initial charge / discharge efficiency, and the rate characteristics all increase. It can be seen that the case where 5 to 25 parts by weight of the deposited carbon is deposited is particularly effective considering that the thermal decomposition proceeds over a relatively short time.

[0140] Accordingly, it can be seen that the present invention can also provide a negative electrode material having high-rate characteristics (e.g., a characteristic in which the discharge capacity at a 5.0C rate is 80% or more of the discharge capacity at a 0.2C rate).

[0141] From the above results, it can be seen that hydrogen can be effectively produced using the hydrogen production method or hydrogen production catalyst of the present invention. Furthermore, since the crystalline carbon formed on the surface of the deposited carbon obtained during the hydrogen production process can be utilized as an anode material for lithium-ion secondary batteries, it can be seen that it is effective in resource utilization. This is because by-product carbon, which was difficult to process during the conventional hydrocarbon pyrolysis, can be usefully used in the production of anode materials for lithium-ion secondary batteries.

[0142] Although the embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical concept or essential features thereof. Therefore, the embodiments described above should be understood to be illustrative in all respects and not restrictive.

[0143] According to the present invention, a hydrogen production method and a catalyst for hydrogen production can be provided that effectively produce hydrogen and utilize resources. Therefore, the present invention has industrial applicability.

Claims

1. (A) A catalyst preparation step for preparing a hydrogen production catalyst made of crystalline carbon as a positive catalyst for the hydrogen production reaction by hydrocarbon thermal decomposition; and (B) Includes a hydrogen generation step for generating hydrogen by thermally decomposing hydrocarbon gas over the catalyst prepared in step (A). The above thermal decomposition takes place at temperatures above 900 degrees Celsius, (C) In the step (B), a lithium ion secondary battery negative electrode material collection step is further included for collecting the crystalline carbon formed on the surface by vapor deposition of carbon generated by the thermal decomposition to utilize it as a negative electrode material for a lithium ion secondary battery. With respect to 100 parts by weight of the above crystal carbon, the deposited carbon is 5 to 25 parts by weight, The above crystal carbon is a method for producing hydrogen using graphite.

2. In the first paragraph, the thermal decomposition is performed at a gas space velocity of 8000 hr. -1 The hydrogen production method performed below.

3. A method for producing hydrogen in accordance with claim 1, wherein the crystalline carbon formed on the surface of the deposited carbon has high-rate characteristics.

4. It is composed of crystalline carbon as a positive catalyst for hydrogen production reaction by hydrocarbon thermal decomposition. The above crystalline carbon has a carbon purity of 95% or more, a hydrocarbon conversion rate of 10% or more, and a hydrogen selectivity of 20% or more. The above hydrocarbon conversion rate and hydrogen selectivity are calculated under thermal decomposition conditions including a temperature condition of 900 degrees Celsius or higher. Carbon generated by the above hydrocarbon thermal decomposition is vapor-deposited on the surface of the above crystalline carbon to form deposited carbon, The above crystalline carbon has a specific surface area of ​​30㎡ / g or less, The above crystal carbon is a catalyst for hydrogen production, which is graphite.

5. In the fourth paragraph, the thermal decomposition conditions are gas space velocity 8000 hr. -1 A catalyst for hydrogen production further comprising the following gas space velocity conditions.

6. In the fourth paragraph, the volume of the crystalline carbon is 8000 hr of the gas space velocity of the hydrocarbon-containing gas. -1 A catalyst for hydrogen production corresponding to the following.

7. In the fourth paragraph, the crystalline carbon is a catalyst for hydrogen production having a deposition surface on which the deposited carbon is deposited.

8. A catalyst for hydrogen production in paragraph 4, wherein the deposited carbon is amorphous carbon.

9. A catalyst for hydrogen production in paragraph 4, wherein the deposited carbon is 5 to 50 parts by weight based on 100 parts by weight of the crystalline carbon.

10. A catalyst for hydrogen production in paragraph 4, wherein the graphite is at least one selected from natural graphite and artificial graphite.

11. In paragraph 4, the crystalline carbon is a catalyst for hydrogen production having an average particle size of 25㎛ or less.

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