A system and method for converting methane into high-purity hydrogen and carbon materials

Abstract

The present invention provides a solution for converting methane into high-purity hydrogen and carbon materials. After removing water and oxygen in the methane gas through a purification device, the methane gas is introduced into a liquid molten metal conversion device to directly crack and obtain carbon material 1 and hydrogen; then, it is further cracked through a gas-phase relay conversion device to obtain carbon material 2 and hydrogen; the generated mixed gas is introduced into a volatile metal recovery device to cool the metal catalyst vapor therein to obtain metal catalyst particles; then, the remaining mixed gas is introduced into a pressure swing adsorption device for separation to obtain hydrogen; and then, the remaining methane gas is introduced into the volatile metal recovery device to cool it, and the condensed metal catalyst particles are carried back to the liquid molten metal conversion device for recycling. This solution realizes the full reuse of methane gas and metal catalyst, can convert methane into carbon materials and high-purity hydrogen to the maximum extent, there is no loss of metal catalyst in the whole process, and it has the advantages of continuous operation and low cost.

Description

Technical Field

[0001] The present invention relates to the technical fields of nanomanufacturing and green hydrogen production, and particularly relates to a system and method for converting methane into high-purity hydrogen and carbon materials. Background Art

[0002] Although the green hydrogen obtained by electrolyzing water is clean, its cost is high, and in terms of the energy consumption per mole of hydrogen, it is the largest among all hydrogen production processes. Methane is an abundant mineral resource, which can come from associated oilfield gas, shale gas or combustible ice, or from coal mine gas, as well as the metabolites of the biochemical process of biomass (such as biogas). Methane is a hydrogen source with the smallest carbon-hydrogen ratio and can obtain the maximum amount of hydrogen.

[0003] Traditional methods for producing hydrogen by steam reforming or partial oxidation are accompanied by a large amount of carbon dioxide emissions. Only the direct cracking of methane can directly fix carbon elements as carbon materials and lay the foundation for obtaining high-purity hydrogen. The catalysts for cracking methane include liquid molten metals or solid catalysts. However, high temperatures are required for operation to obtain the corresponding high conversion rates thermodynamically. This results in rapid deactivation of solid catalysts (sintering or carbon coating) or losses of liquid molten metal catalysts. So far, these drawbacks have not been well solved. Summary of the Invention

[0004] In view of the above problems existing in the prior art, the present invention discloses a method for converting methane into high-purity hydrogen and carbon materials, which includes the following steps:

[0005] S1. Pass the raw material gas into the purification device 1 to absorb water and oxygen therein, and obtain clean methane;

[0006] S2. Pass the clean methane into the liquid molten metal conversion device 2, and crack methane under the action of a metal catalyst to obtain a mixture 1 containing hydrogen and carbon material 1;

[0007] S3. Pass the mixture 1 into the gas-phase relay conversion device 3 to continue cracking the methane therein, and obtain a mixture 2 containing carbon material 1, carbon material 2 and hydrogen;

[0008] S4. Pass the gaseous components in the mixture 2 into the volatile metal recovery device 4 for cooling, so that the metal catalyst vapor therein condenses to form metal catalyst particles and a mixed gas 3;

[0009] S5. Pass the mixed gas 3 into the pressure swing adsorption device 5, separate hydrogen through pressure swing adsorption, then pass the unreacted methane into the volatile metal recovery device 4 for indirect heat exchange, and then mix it with the metal catalyst particles and transfer it to the liquid molten metal conversion device 2 for recycling.

[0010] Optionally, in step S1, a microporous adsorbent is filled inside the purification device; the contact time between the microporous adsorbent and the raw material gas is 3 to 200 seconds; the contents of water and oxygen in the purified methane are both within 1 mg / m 3 Below.

[0011] Optionally, in step S2, the metal catalyst is one or at least two of copper, nickel, aluminum, zinc, bismuth, manganese, lead, and tin; the operating temperature of the metal catalyst is 850 to 1200 °C; the contact time between the metal catalyst and the purified methane is 3 to 30 seconds.

[0012] Optionally, in step S2, the component of the carbon material 1 is graphene with a mass fraction of 75% to 99.9% and carbon nanotubes with a mass fraction of 0.1% to 25%.

[0013] Optionally, in step S3, the cracking temperature of the gas-phase relay conversion device is 800 to 900 °C.

[0014] Optionally, in step S3, it further includes: when the total volume of the carbon material 1 and the carbon material 2 reaches 1 / 2 to 3 / 4 of the volume of the gas-phase relay conversion device, unloading is carried out;

[0015] After unloading, in the gas-phase relay conversion device, the total volume of the carbon material 1 and the carbon material 2 is maintained at 1 / 3 to 1 / 2 of the volume of the gas-phase relay conversion device.

[0016] Optionally, in step S4, the diameter of the metal catalyst particles is 1 to 500 nm.

[0017] Optionally, in step S5, the purity of the hydrogen separated by the pressure swing adsorption device 5 > 99.999%.

[0018] To solve the above problems, the present invention also discloses a system for converting methane into high-purity hydrogen and carbon materials, the system includes: a purification device 1 for absorbing water and oxygen in the raw material gas;

[0019] A liquid molten metal conversion device 2 connected to the gas outlet a7 of the purification device 1, for cracking methane under the action of a metal catalyst to obtain a mixture 1 containing hydrogen and carbon material 1;

[0020] A gas-phase relay conversion device 3 connected to the gas-solid outlet a9 of the liquid molten metal conversion device 2, for cracking methane in the mixture 1 discharged from the liquid molten metal conversion device 2 to obtain a mixture 2 containing carbon material 1, carbon material 2, and hydrogen;

[0021] The volatile metal recovery device 4 connected to the gas outlet b12 of the gas-phase relay conversion device 3 is used to cool the gaseous components in the mixture 2 discharged from the gas-phase relay conversion device 3, condense the metal catalyst vapor therein, and form metal catalyst particles and mixed gas 3;

[0022] The pressure swing adsorption device 5 connected to the gas outlet c14 of the volatile metal recovery device 4 is used to separate hydrogen and unreacted methane in the mixed gas 3 discharged from the volatile metal recovery device 4;

[0023] The heat exchange gas outlet 18 is provided at the top of the pressure swing adsorption device 5. The heat exchange gas outlet 18 is connected to the heat exchange gas inlet 15 of the volatile metal recovery device 4 through a pipeline, and the unreacted methane is returned to the volatile metal recovery device 4 for indirect heat exchange and mixed with the metal catalyst particles;

[0024] The gas-solid outlet b16 is provided at the bottom of the volatile metal recovery device 4. The gas-solid outlet b16 is connected to the gas inlet b8 of the liquid molten metal conversion device 4 through a pipeline, and the unreacted methane and the metal catalyst particles are transported to the liquid molten metal conversion device 2 for recycling.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] By providing a precise purification device, this application can avoid the interference of water and oxygen on the activity of molten metal, reduce the complexity of subsequent gas separation, and the cost is reduced by 10-20%; by providing a liquid molten metal conversion device and a gas-phase relay conversion device, methane gas is continuously cracked, effectively improving the conversion rate of methane gas. Moreover, the temperature set in the gas-phase relay conversion device is lower than that in the liquid molten metal conversion device, which is conducive to the condensation of metal catalyst vapor into a single-molecule catalyst or metal pair catalyst with higher activity. Compared with ordinary supported catalysts and metal catalyst components in the molten metal device, the activity can be increased by 30-50%, and the overall cost is reduced by 30-50%.

[0027] This application also separates methane gas and hydrogen by providing a pressure swing adsorption device, and passes the methane gas into the volatile metal recovery device for the condensation of metal catalyst vapor, realizing partial preheating of the device, which can save 20% of energy. The methane gas carries the condensed metal catalyst particles into the liquid molten metal conversion device for recycling, realizing the full reuse of methane gas and metal catalyst. The purity of the collected hydrogen >99.999%, and compared with ordinary systems and methods for converting methane into hydrogen, the hydrogen purity is increased by at least 40%.

[0028] The system provided by the present application for converting methane into high-purity hydrogen and carbon materials connects a purification device, a liquid molten metal conversion device, a gas-phase relay conversion device, a volatile metal recovery device, and a pressure swing adsorption device, fully recycling methane gas and metal catalysts, achieving the maximum conversion of methane into carbon materials and high-purity hydrogen, and having the advantages of continuous operation and low cost without any loss of metal catalysts throughout the process. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 It shows the flowchart of the method for converting methane into high-purity hydrogen and carbon materials provided by the embodiments of the present invention;

[0031] Figure 2 It shows the schematic diagram of the system for converting methane into high-purity hydrogen and carbon materials provided by the embodiments of the present invention.

[0032] Description of the Reference Numerals:

[0033] 1 - Purification device, 2 - Liquid molten metal conversion device, 3 - Gas-phase relay conversion device, 4 - Volatile metal recovery device, 5 - Pressure swing adsorption device, 6 - Gas inlet a, 7 - Gas outlet a, 8 - Gas inlet b, 9 - Gas-solid outlet a, 10 - Gas-solid inlet, 11 - Solid outlet, 12 - Gas outlet b, 13 - Gas inlet c, 14 - Gas outlet c, 15 - Heat exchange gas inlet, 16 - Gas-solid outlet b, 17 - Gas inlet d, 18 - Heat exchange gas outlet, 19 - Gas outlet e. Detailed Embodiments

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all of them. The description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features and being the same or similar to the present invention falls within the protection scope of the present invention. And all other embodiments obtained by those of ordinary skill in the art without creative efforts also belong to the protection scope of the present invention.

[0035] When converting methane into high-purity hydrogen and carbon materials based on the prior art, there are problems such as loss of metal catalysts and low methane conversion rate. A solution for converting methane into high-purity hydrogen and carbon materials provided by the embodiments of the present application, after removing water and oxygen in the methane gas through the purification device 1, the methane gas is introduced into the liquid molten metal conversion device 2 to directly crack and obtain carbon material 1 and hydrogen; then through gas-phase relay conversion 3, the remaining methane in the gas is further cracked to obtain carbon material 2 and hydrogen; the generated mixed gas is introduced into the volatile metal recovery device 4 to cool the metal catalyst vapor therein to obtain metal catalyst particles; then the remaining mixed gas is introduced into the pressure swing adsorption device 5 for separation to obtain high-purity hydrogen and unreacted methane gas; and the unreacted methane gas is introduced into the volatile metal recovery device 4 again, which can also be used as a heat exchange medium to cool the volatile metal recovery device 4 and carry the condensed metal catalyst particles back to the liquid molten metal conversion device 2 for recycling. The specific implementation method is as follows:

[0036] In a first aspect, the present invention provides a method for converting methane into high-purity hydrogen and carbon materials, Figure 1 which shows the flow chart of the method for converting methane into high-purity hydrogen and carbon materials provided by the embodiments of the present invention, as Figure 1 shown, including the following steps:

[0037] S1. Introduce the raw material gas into the purification device 1 to absorb water and oxygen therein to obtain clean methane;

[0038] When specifically implementing this step, the purification device 1 is filled with microporous adsorbent inside; the raw material gas is input into the purification device 1, and after contacting the microporous adsorbent for 3 to 200 seconds, oxygen and water are adsorbed on the microporous adsorbent to obtain clean methane; the contents of water and oxygen in the clean methane are both below 1 mg / m 3 below.

[0039] S2. Introduce the clean methane into the liquid molten metal conversion device 2 to crack methane under the action of a metal catalyst to obtain a mixture 1 containing hydrogen and carbon material 1;

[0040] In the specific implementation of this step, the purification device 1, the liquid molten metal conversion device 2, the gas-phase relay conversion device 3, the volatile metal recovery device 4, and the pressure swing adsorption device 5 are connected in sequence; then the heat exchange gas outlet 18 at the top of the pressure swing adsorption device 5 is connected to the heat exchange gas inlet 15 of the volatile metal recovery device 4; then the gas-solid outlet b16 at the bottom of the volatile metal recovery device 4 is connected to the gas inlet b8 of the liquid molten metal conversion device 2 through a pipeline. The clean methane is discharged from the purification device 1 and introduced into the liquid molten metal conversion device 2; the liquid molten metal conversion device 2 is filled with molten metal catalyst, and the metal catalyst is one or at least two of copper, nickel, aluminum, zinc, bismuth, manganese, lead, and tin; the molten metal catalyst contacts the clean methane at 850-1200 °C for 3-30 seconds to catalyze the cracking of methane gas, and a mixture 1 containing unreacted methane gas, metal catalyst vapor, carbon material 1, and hydrogen is obtained; in the liquid molten metal conversion device 2, the conversion rate of methane directly cracked into hydrogen is 85-90%, and the component of carbon material 1 is graphene with a mass fraction of 75%-99.9% and carbon nanotubes with a mass fraction of 0.1%-25%.

[0041] S3. Introduce the mixture 1 into the gas-phase relay conversion device 3 to continue cracking the methane therein, and obtain a mixture 2 containing carbon material 1, carbon material 2, and hydrogen;

[0042] In the specific implementation of this step, the mixture 1 is introduced into the gas-phase relay conversion device 3, the temperature inside the gas-phase relay conversion device 3 is controlled to be 800-900 °C, and all substances are in a fluidized state; the metal catalyst vapor catalyzes the continuous cracking of methane gas to generate carbon material 2 and hydrogen, and a mixture 2 containing unreacted methane gas, metal catalyst vapor, carbon material 1, carbon material 2, and hydrogen is obtained; the component of carbon material 2 is carbon nanotubes with a mass fraction of 75%-99.9% and nano-carbon particles or nano-carbon fibers with a mass fraction of 0.1%-25%. When the volume of carbon material 1 and carbon material 2 reaches 1 / 2-3 / 4 of the volume of device 3, discharging is carried out. After discharging, the total volume of carbon material 1 and carbon material 2 in the gas-phase relay conversion device 3 remains at 1 / 3-1 / 2 of the volume of the gas-phase relay conversion device 3 to ensure a relatively stable fluidized state in the reactor fluidized bed. Through the collaborative catalysis of methane gas cracking by the liquid molten metal conversion device 2 and the gas-phase relay conversion device 3, the total conversion rate of methane gas into hydrogen reaches 92-95%.

[0043] S4. Cool the gaseous components in the mixture 2 in the volatile metal recovery device 4 to condense the metal catalyst vapor therein to form metal catalyst particles and a mixed gas 3;

[0044] When this step is specifically implemented, the gaseous components in the mixture 2, namely methane gas, hydrogen gas, and metal catalyst vapor, are introduced into the volatile metal recovery device 4 for cooling. All of the metal catalyst vapor condenses to form metal catalyst particles with a diameter of 1 to 500 nm. The temperature in the volatile metal recovery device 4 is lower than 100 °C.

[0045] S5. The mixed gas 3 is introduced into the pressure swing adsorption device 5. Through pressure swing adsorption, hydrogen is separated out. Then, the unreacted methane is introduced into the volatile metal recovery device 4 for indirect heat exchange, and then after being mixed with the metal catalyst particles, it is transmitted to the liquid molten metal conversion device 2 for recycling.

[0046] When this step is specifically implemented, the mixed gas 3 composed of methane and hydrogen is introduced into the pressure swing adsorption device 5 for pressure swing adsorption separation to obtain high-purity hydrogen gas and methane gas; the hydrogen separated out by the pressure swing adsorption device 5 is collected, and the hydrogen purity > 99.999%; the unreacted methane gas after separation is introduced into the volatile metal recovery device 4 again for indirect heat exchange, and it is transmitted to the liquid molten metal device 2 while carrying the metal catalyst particles to continue the cyclic reaction.

[0047] In a second aspect, an embodiment of the present invention provides a system for converting methane into high-purity hydrogen and carbon materials, as Figure 2As shown in the figure, the system includes a purification device 1 for absorbing water and oxygen in the raw material gas; a liquid molten metal conversion device 2 connected to the gas outlet a7 of the purification device 1 for cracking methane under the action of a metal catalyst to obtain a mixture 1 containing hydrogen and carbon material 1; a gas-phase relay conversion device 3 connected to the gas-solid outlet a9 of the liquid molten metal conversion device 2 for cracking the methane gas in the mixture 1 discharged from the gas-solid outlet a9 of the liquid molten metal conversion device 2 to obtain a mixture 2 containing carbon material 1, carbon material 2 and hydrogen; a volatile metal recovery device 4 connected to the gas outlet b12 of the gas-phase relay conversion device 3 for cooling the gaseous components in the mixture 2 discharged from the gas outlet b12 of the gas-phase relay conversion device 3 to condense the metal catalyst vapor therein to form metal catalyst particles and a mixed gas 3; a pressure swing adsorption device 5 connected to the gas outlet c14 of the volatile metal recovery device 4 for separating hydrogen and unreacted methane in the mixed gas 3 discharged from the gas outlet c14 of the volatile metal recovery device 4; a heat exchange gas outlet 18 is provided at the top of the pressure swing adsorption device 5, and the heat exchange gas outlet 18 is connected to the heat exchange gas inlet 15 of the volatile metal recovery device 4 through a pipeline to return the unreacted methane gas to the volatile metal recovery device 4 for indirect heat exchange and mix it with the metal catalyst particles; a gas-solid outlet b16 is provided at the bottom of the volatile metal recovery device 4, and the gas-solid outlet b16 is connected to the gas inlet b8 of the liquid molten metal conversion device 2 through a pipeline to transfer the unreacted methane and the metal catalyst particles to the liquid molten metal conversion device 2 for recycling.

[0048] The solution for converting methane into high-purity hydrogen and carbon materials provided by this application connects the purification device 1, the liquid molten metal conversion device 2, the gas-phase relay conversion device 3, the volatile metal recovery device 4 and the pressure swing adsorption device 5, fully recycling the methane gas and the metal catalyst, achieving the maximum conversion of methane into carbon materials and high-purity hydrogen, and having the advantages of continuous operation and low cost throughout the process without any loss of the metal catalyst.

[0049] To enable those skilled in the art to understand the present invention more clearly, the following embodiments are now used to elaborate in detail on a system and method for converting methane into high-purity hydrogen and carbon materials described in the present invention.

[0050] Example 1

[0051] Connect devices 1-5 in sequence. The heat exchange gas outlet 18 of device 5 is connected to the heat exchange gas inlet 15 of device 4 through a pipeline, and the gas-solid outlet b16 of device 4 is connected to the gas inlet b8 of device 2 through a pipeline. A complete system is formed.

[0052] Load a microporous adsorbent into Device 1 and operate at room temperature. Pass methane through gas inlet a6, and by contacting with the adsorbent for 3 seconds, remove both water and oxygen in the methane to below 1 mg / m 3 as follows.

[0053] After the methane exits Device 1 through gas outlet a7, it enters Device 2 through gas inlet b8, is converted in molten metal (90% nickel, 3% zinc, 2% bismuth, 5% manganese), with the temperature controlled at 1200 °C and the contact time at 3 seconds, to produce Carbon Material 1 (93% graphene and 7% carbon nanotubes). The methane conversion rate reaches 85%. The product gas (methane and hydrogen), Carbon Material 1, and metal catalyst vapors (zinc, bismuth, manganese) together exit Device 2 through gas-solid outlet a9 and enter Device 3 through gas-solid inlet 10.

[0054] In Device 3, control all materials to be in a fluidized state, control the temperature at 900 °C, and the metal catalyst vapors act as a catalyst to continue converting the residual methane, so that the total methane conversion rate reaches 92%, and continue to produce Carbon Material 2 (99.9% carbon nanotubes and 0.1% nano-carbon particles).

[0055] In the fluidized bed state, when the volume of Carbon Material 2 and Carbon Material 1 reaches 3 / 4 of the volume of Device 3, discharge through outlet 11. Control the carbon material volume to remain at 1 / 2 of the volume of Device 3.

[0056] The product gas and volatile metal exit Device 3 through gas outlet b12 and enter Device 4 through gas inlet c13. Through indirect heat exchange, the temperature of the metal catalyst vapors is lowered below 100 °C and all condense into particles with a diameter of 1 - 100 nm.

[0057] The cooled gas exits Device 4 through gas outlet c14 and enters Device 5 through gas inlet d17. Through pressure swing adsorption, high-purity hydrogen is obtained and exits Device 5 through gas outlet e19.

[0058] The gas enriched in methane obtained by pressure swing separation (methane concentration is 90%), with the temperature controlled to room temperature, exits Device 5 through gas outlet d18. Then it enters Device 4 through heat exchange gas inlet 15 and conducts indirect heat exchange with the metal catalyst vapors and the gas therein.

[0059] After the metal catalyst vapors in Device 4 condense and deposit, they are carried by the gas enriched in methane and exit Device 4 through gas-solid outlet b16.

[0060] The metal catalyst particles and the gas enriched in methane enter Device 2 through gas inlet b8 for cyclic conversion.

[0061] Repeat the above operations to continuously convert methane into hydrogen with a purity > 99.999%.

[0062] Example 2:

[0063] Connect devices 1 - 5 in sequence. The heat exchange gas outlet 18 of device 5 is connected to the heat exchange gas inlet 15 of device 4 through a pipeline, and the gas - solid outlet b16 of device 4 is connected to the gas inlet b8 of device 2 through a pipeline, forming a complete system.

[0064] Load microporous adsorbent in device 1 and operate at room temperature. Introduce methane through the gas inlet a6, and after contacting the adsorbent for 200 seconds, remove both water and oxygen in methane to less than 1 mg / m 3 below.

[0065] After methane exits device 1 through the gas outlet a7, it enters device 2 through the gas inlet b8, is converted in molten metal (80% copper, 5% aluminum, 6% zinc, 4% lead, 5% tin), with the temperature controlled at 850 °C and the contact time of 30 seconds, to generate carbon material 1 (75% graphene and 25% carbon nanotubes). The methane conversion rate reaches 90%. The product gas (methane and hydrogen), carbon material 1, and metal catalyst vapors (zinc, bismuth, manganese) together exit device 2 through the gas - solid outlet a9 and enter device 3 through the gas - solid inlet 10.

[0066] In device 3, control all materials in a fluidized state, control the temperature at 800 °C, and the metal catalyst vapors act as a catalyst to continue converting the residual methane, making the total methane conversion rate reach 95%, and continue to generate carbon material 2 (75% carbon nanotubes and 25% nano - carbon particles).

[0067] In the fluidized - bed state, when the volume of carbon material 2 and carbon material 1 reaches 3 / 4 of the volume of device 3, discharge through the outlet 11. Control the carbon material volume to remain at 1 / 2 of the volume of device 3.

[0068] The product gas and metal catalyst vapors exit device 3 through the gas outlet b12, enter device 4 through the gas inlet c13. After indirect heat exchange, the temperature of the metal catalyst vapors is lowered below 100 °C and all condense into particles with a diameter of 1 - 500 nm.

[0069] The cooled gas exits device 4 through the gas outlet c14, enters device 5 through the gas inlet d17, and through pressure swing adsorption, high - purity hydrogen is obtained and exits device 5 through the gas outlet e19.

[0070] The gas enriched with methane obtained by pressure swing separation (methane concentration is 10%), with the temperature controlled to room temperature, exits device 5 through the gas outlet d18. Then it enters device 4 through the heat exchange gas inlet 15 and conducts indirect heat exchange with the metal catalyst vapors and the gas therein.

[0071] After the metal catalyst vapors in device 4 condense and deposit, they are carried by the methane - enriched gas and exit device 4 through the gas - solid outlet b16.

[0072] The metal catalyst particles and the methane-enriched gas enter the device 2 through the gas inlet b8 and undergo cyclic conversion.

[0073] By repeating the above operation, methane can be continuously converted into hydrogen with a purity > 99.999%.

[0074] Example 3:

[0075] Connect devices 1 - 5 in sequence. The heat exchange gas outlet 18 of device 5 is connected to the heat exchange gas inlet 15 of device 4 through a pipeline, and the gas-solid outlet b16 of device 4 is connected to the gas inlet b8 of device 2 through a pipeline. A complete system is formed.

[0076] Load microporous adsorbent in device 1 and operate at room temperature. Pass methane through the gas inlet a6, and by contacting with the adsorbent for 20 seconds, both water and oxygen in the methane are removed to less than 1 mg / m 3 as follows.

[0077] After the methane exits device 1 through the gas outlet a7, it enters device 2 through the gas inlet b8 and is converted in the molten metal (97% copper, 1% nickel, 2% bismuth). Control the temperature at 900 °C and the contact time at 10 seconds to generate carbon material 1 (99.9% graphene and 0.1% carbon nanotubes). The methane conversion rate reaches 88%. The product gas (methane and hydrogen), carbon material 1, and metal catalyst vapor (zinc, bismuth, manganese) together exit device 2 through the gas-solid outlet a9 and enter device 3 through the gas-solid inlet 10.

[0078] In device 3, control all the materials to be in a fluidized state, control the temperature at 880 °C, and the metal catalyst vapor acts as a catalyst to continue converting the residual methane, so that the total methane conversion rate reaches 93%, and continue to generate carbon material 2 (85% carbon nanotubes, 5% nano-carbon particles, 10% nano-carbon fibers).

[0079] In the fluidized bed state, when the volume of carbon material 2 and carbon material 1 reaches 3 / 4 of the volume of device 3, discharge through the outlet 11. Control the carbon material volume to remain at 1 / 3 of the volume of device 3.

[0080] The product gas and the metal catalyst vapor exit device 3 through the gas outlet b12 and enter device 4 through the gas inlet c13. Through indirect heat exchange, the temperature of the metal catalyst vapor is lowered below 100 °C and all condenses into particles with a diameter of 20 - 200 nm.

[0081] The cooled gas exits device 4 through the gas outlet c14, enters device 5 through the gas inlet d17, and high-purity hydrogen is obtained through pressure swing adsorption and exits device 5 through the gas outlet e19.

[0082] The gas enriched with methane obtained by pressure transformation and separation (methane concentration is 50%) is controlled to room temperature and exits device 5 through gas outlet d18. Then it enters device 4 through heat exchange gas inlet 15 and indirectly exchanges heat with the metal catalyst vapor and the gas therein.

[0083] After the metal catalyst vapor in device 4 condenses and deposits, it is carried by the gas enriched with methane and exits device 4 from gas-solid outlet b16.

[0084] The metal catalyst particles and the gas enriched with methane enter device 2 through gas inlet b8 for cyclic conversion.

[0085] Repeating the above operations can continuously convert methane into hydrogen with a purity > 99.999%.

[0086] Example 4

[0087] Connect devices 1 - 5 in sequence. The heat exchange gas outlet 18 of device 5 is connected to the heat exchange gas inlet 15 of device 4 through a pipeline, and the gas-solid outlet b16 of device 4 is connected to the gas inlet b8 of device 2 through a pipeline. A complete system is formed.

[0088] Load microporous adsorbent in device 1 and operate at room temperature. Pass methane through gas inlet a6 and remove both water and oxygen in methane to 1 mg / m 3 below.

[0089] After methane exits device 1 through gas outlet a7, it enters device 2 through gas inlet b8 and is converted in molten metal (40% copper, 20% nickel, 5% aluminum, 35% zinc). Control the temperature at 1100 °C and the contact time at 20 seconds to generate carbon material 1 (75% graphene and 25% carbon nanotubes). The methane conversion rate reaches 90%. The product gas (methane and hydrogen), carbon material 1, and metal catalyst vapor (zinc, bismuth, manganese) together exit device 2 from gas-solid outlet a9 and enter device 3 through gas-solid inlet 10.

[0090] In device 3, control all materials to be in a fluidized state, control the temperature at 800 °C, and the metal catalyst vapor acts as a catalyst to continue converting the residual methane, so that the total methane conversion rate reaches 95%, and continue to generate carbon material 2 (75% carbon nanotubes, 20% nano carbon particles, 5% nano carbon fibers).

[0091] In the fluidized bed state, when the volume of carbon material 2 and carbon material 1 reaches 1 / 2 of the volume of device 3, discharge through outlet 11. Control the carbon material volume to remain at 1 / 3 of the volume of device 3.

[0092] The product gas and the vapor of the metal catalyst exit the device 3 through the gas outlet b12 and enter the device 4 through the gas inlet c13. Through indirect heat exchange, the temperature of the vapor of the metal catalyst is lowered below 100 °C and all condenses into particles with a diameter of 300 - 400 nm.

[0093] The cooled gas exits the device 4 through the gas outlet c14, enters the device 5 through the gas inlet d17, and high-purity hydrogen is obtained through pressure swing adsorption and exits the device 5 through the gas outlet e19.

[0094] The gas enriched in methane (methane concentration is 70%) obtained by pressure swing separation is controlled to room temperature and exits the device 5 through the gas outlet d18. Then it enters the device 4 through the heat exchange gas inlet 15 and indirectly exchanges heat with the vapor of the metal catalyst and the gas therein.

[0095] After the vapor of the metal catalyst in the device 4 condenses and deposits, it is carried by the gas enriched in methane and exits the device 4 from the gas-solid outlet b16.

[0096] The metal catalyst particles and the gas enriched in methane enter the device 2 through the gas inlet b8 for cyclic conversion.

[0097] By repeating the above operations, methane can be continuously converted into hydrogen with a purity > 99.999%.

[0098] Example 5

[0099] Connect the devices 1 - 5 in sequence. The heat exchange gas outlet 18 of the device 5 is connected to the heat exchange gas inlet 15 of the device 4 through a pipeline, and the gas-solid outlet b16 of the device 4 is connected to the gas inlet b8 of the device 2 through a pipeline. A complete system is formed.

[0100] Load a microporous adsorbent in the device 1 and operate at room temperature. Methane is introduced through the gas inlet a6 and, by contacting the adsorbent for 50 seconds, both the water and oxygen in the methane are removed to 1 mg / m 3 below.

[0101] After the methane exits the device 1 through the gas outlet a7, it enters the device 2 through the gas inlet b8 and is converted in the molten metal (20% copper, 30% nickel, 20% aluminum, 10% lead, 20% tin). The temperature is controlled at 1000 °C and the contact time is 12 seconds to generate carbon material 1 (98% graphene and 2% carbon nanotubes). The methane conversion rate reaches 87%. The product gas (methane and hydrogen), carbon material 1 and the vapor of the metal catalyst (zinc, bismuth, manganese) together exit the device 2 from the gas-solid outlet a9 and enter the device 3 through the gas-solid inlet 10.

[0102] In apparatus 3, all the materials are controlled to be in a fluidized state, the temperature is controlled at 900 °C, and the metal catalyst vapor acts as a catalyst to continue converting the residual methane, so that the total methane conversion rate reaches 95%, and carbon material 2 (99.9% carbon nanotubes and 0.1% nanofibers) is continuously produced.

[0103] In the fluidized bed state, when the volume of carbon material 2 and carbon material 1 reaches 3 / 4 of the volume of apparatus 3, discharging is carried out through outlet 11. The volume of the carbon material is controlled to remain at 1 / 3 of the volume of apparatus 3.

[0104] The product gas and the metal catalyst vapor leave apparatus 3 through gas outlet b12 and enter apparatus 4 through gas inlet c13. Through indirect heat exchange, the temperature of the metal catalyst vapor is lowered below 100 °C and all condenses into particles with a diameter of 1 - 10 nm.

[0105] The cooled gas leaves apparatus 4 through gas outlet c14, enters apparatus 5 through gas inlet d17, and high-purity hydrogen is obtained through pressure swing adsorption and leaves apparatus 5 through gas outlet e19.

[0106] The gas enriched with methane obtained by pressure swing separation (methane concentration is 40%) is controlled to room temperature and leaves apparatus 5 through gas outlet d18. Then it enters apparatus 4 through heat exchange gas inlet 15 and conducts indirect heat exchange with the metal catalyst vapor and the gas therein.

[0107] After the metal catalyst vapor in apparatus 4 condenses and deposits, it is carried by the gas enriched with methane and leaves apparatus 4 through gas-solid outlet b16.

[0108] The metal catalyst and the gas enriched with methane enter apparatus 2 through gas inlet b8 for cyclic conversion.

[0109] By repeating the above operations, methane can be continuously converted into hydrogen with a purity > 99.999%.

[0110] Example 6

[0111] Apparatus 1 - 5 are connected in sequence. The heat exchange gas outlet 18 of apparatus 5 is connected to the heat exchange gas inlet 15 of apparatus 4 through a pipeline, and the gas-solid outlet b16 of apparatus 4 is connected to the gas inlet b8 of apparatus 2 through a pipeline. A complete system is formed.

[0112] Microporous adsorbent is loaded in apparatus 1 and it works at room temperature. Methane is introduced through gas inlet a6, and by contacting with the adsorbent for 40 seconds, both water and oxygen in the methane are removed to less than 1 mg / m 3 as follows.

[0113] After methane exits device 1 through gas outlet a7, it enters device 2 through gas inlet b8 and is converted in molten metal (60% copper, 30% nickel, 5% bismuth, 5% manganese) at a controlled temperature of 1200 °C and a contact time of 30 seconds to produce carbon material 1 (90% graphene and 10% carbon nanotubes). The methane conversion rate reaches 90%. The product gas (methane and hydrogen), carbon material 1, and metal catalyst vapor (zinc, bismuth, manganese) together exit device 2 through gas-solid outlet a9 and enter device 3 through gas-solid inlet 10.

[0114] In device 3, all materials are controlled to be in a fluidized state at a temperature of 900 °C. The metal catalyst vapor acts as a catalyst to continue converting the residual methane, increasing the total methane conversion rate to 94.5% and continuing to produce carbon material 2 (95% carbon nanotubes and 5% nano carbon particles).

[0115] In the fluidized bed state, when the volume of carbon material 2 and carbon material 1 reaches 3 / 4 of the volume of device 3, discharging is carried out through outlet 11. The volume of carbon material is controlled to remain at 1 / 2 of the volume of device 3.

[0116] The product gas and metal catalyst vapor exit device 3 through gas outlet b12 and enter device 4 through gas inlet c13. Through indirect heat exchange, the temperature of the metal catalyst vapor is lowered below 100 °C and all condenses into particles with a diameter of 10 - 50 nm.

[0117] The cooled gas exits device 4 through gas outlet c14 and enters device 5 through gas inlet d17. Through pressure swing adsorption, high-purity hydrogen is obtained and exits device 5 through gas outlet e19.

[0118] The gas enriched in methane obtained by pressure swing separation (methane concentration is 80%) is controlled to room temperature and exits device 5 through gas outlet d18. Then it enters device 4 through heat exchange gas inlet 15 and undergoes indirect heat exchange with the metal catalyst vapor and the gas therein.

[0119] After the metal catalyst vapor in device 4 condenses and deposits, it is carried by the gas enriched in methane and exits device 4 through gas-solid outlet b16.

[0120] The metal catalyst particles and the gas enriched in methane enter device 2 through gas inlet b8 for cyclic conversion.

[0121] By repeating the above operations, methane can be continuously converted into hydrogen with a purity > 99.999%.

[0122] As can be seen from Examples 1 to 6, the conversion rate of methane can reach up to 95%, and the purity of the obtained hydrogen is >99.999%. Compared with the traditional scheme for converting methane into hydrogen, this scheme can greatly improve the conversion rate of methane, with a maximum increase of 40%, and the purity of hydrogen is increased by at least 40%. The scheme provided in this application for converting methane into high-purity hydrogen and carbon materials connects a purification device, a liquid molten metal conversion device, a gas-phase relay conversion device, a volatile metal recovery device, and a pressure swing adsorption device, fully recycling methane gas and metal catalysts, achieving the maximum conversion of methane into carbon materials and high-purity hydrogen, and having the advantages of continuous operation and low cost without any loss of metal catalysts throughout the process.

[0123] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0124] For method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0125] The above has introduced in detail a system and method for converting methane into high-purity hydrogen and carbon materials provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for converting methane into high-purity hydrogen and carbon materials, characterized in that, It includes the following steps: S1. Feed the raw material gas into the purification device (1) to absorb water and oxygen therein, and obtain clean methane; S2. Feed the clean methane into the liquid molten metal conversion device (2), and crack the methane under the action of a metal catalyst to obtain a mixture 1 containing hydrogen and carbon material 1; S3. Feed the mixture 1 into the gas-phase relay conversion device (3) to continue cracking the methane therein, and obtain a mixture 2 containing carbon material 1, carbon material 2 and hydrogen; S4. Feed the gaseous components in the mixture 2 into the volatile metal recovery device (4) for cooling to condense the metal catalyst vapor therein, forming metal catalyst particles and a mixed gas 3; S5. Feed the mixed gas 3 into the pressure swing adsorption device (5), separate hydrogen through pressure swing adsorption, then feed the unreacted methane into the volatile metal recovery device (4) for indirect heat exchange, and then mix it with the metal catalyst particles and transfer it to the liquid molten metal conversion device (2) for recycling.

2. The method according to claim 1, characterized in that, In step S1, the purification device is filled with a microporous adsorbent inside; the contact time between the microporous adsorbent and the raw material gas is 3 to 200 seconds; the contents of water and oxygen in the purified methane are both below 1 mg / m 3 below.

3. The method according to claim 1, wherein In step S2, the metal catalyst is one or at least two of copper, nickel, aluminum, zinc, bismuth, manganese, lead, and tin; the operating temperature of the metal catalyst is 850-1200 °C; the contact time between the metal catalyst and the clean methane is 3-30 seconds.

4. The method according to claim 1, characterized in that In step S2, the carbon material 1 consists of graphene with a mass fraction of 75%-99.9% and carbon nanotubes with a mass fraction of 0.1%-25%.

5. The method according to claim 1, characterized in that In step S3, the carbon material 2 consists of carbon nanotubes with a mass fraction of 75%-99.9% and nano-carbon particles or nano-carbon fibers with a mass fraction of 0.1%-25%.

6. The method according to claim 1, wherein In step S3, the cracking temperature of the gas-phase relay conversion device is 800-900 °C.

7. The method according to claim 1, wherein In step S3, it further includes: when the total volume of the carbon material 1 and the carbon material 2 reaches 1 / 2-3 / 4 of the volume of the gas-phase relay conversion device, unloading is carried out; After unloading, in the gas-phase relay conversion device, the total volume of the carbon material 1 and the carbon material 2 remains 1 / 3-1 / 2 of the volume of the gas-phase relay conversion device.

8. The method according to claim 1, wherein In step S4, the diameter of the metal catalyst particles is 1-500 nm.

9. The method according to claim 1, wherein In step S5, the purity of the hydrogen separated by the pressure swing adsorption device (5) >99.999%.

10. A system for converting methane into high-purity hydrogen and carbon materials, characterized in that, The system includes: a purification device (1) for absorbing water and oxygen in the raw material gas; A liquid molten metal conversion device (2) connected to the gas outlet a (7) of the purification device (1) for cracking methane under the action of a metal catalyst to obtain a mixture 1 containing hydrogen and carbon material 1; A gas-phase relay conversion device (3) connected to the gas-solid outlet a (9) of the liquid molten metal conversion device (2) for cracking the methane in the mixture 1 discharged from the liquid molten metal conversion device (2) to obtain a mixture 2 containing carbon material 1, carbon material 2 and hydrogen; A volatile metal recovery device (4) connected to the gas outlet b (12) of the gas-phase relay conversion device (3) is used to cool the gaseous components in the mixture 2 discharged from the gas-phase relay conversion device (3), condense the metal catalyst vapor therein, and form metal catalyst particles and a mixed gas 3; A pressure swing adsorption device (5) connected to the gas outlet c (14) of the volatile metal recovery device (4) is used to separate hydrogen and unreacted methane in the mixed gas 3 discharged from the volatile metal recovery device (4); A heat exchange gas outlet (18) is provided at the top of the pressure swing adsorption device (5), and the heat exchange gas outlet (18) is connected to the heat exchange gas inlet (15) of the volatile metal recovery device (4) through a pipeline to return the unreacted methane to the volatile metal recovery device (4) for indirect heat exchange and mix it with the metal catalyst particles; A gas-solid outlet b (16) is provided at the bottom of the volatile metal recovery device (4), and the gas-solid outlet b (16) is connected to the gas inlet b (8) of the liquid molten metal conversion device (2) through a pipeline to transfer the unreacted methane and the metal catalyst particles to the liquid molten metal conversion device (2) for recycling.

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