Method for extracting high purity hydrogen from hydrogen-natural gas mixtures

Abstract

The application discloses a method for extracting high-purity hydrogen from hydrogen-natural gas mixed components, and specifically comprises the following steps: step 1, preparing a platinum-based MXene / MAX hybrid monomer catalyst; step 2, carrying out a hydrogenation reaction of hydrogen-mixed natural gas and toluene under the action of the catalyst obtained in step 1 to obtain methylcyclohexane and realize hydrogen storage; and step 3, carrying out a dehydrogenation reaction on the methylcyclohexane obtained in step 2 under the catalysis of the catalyst obtained in step 1 to obtain toluene and hydrogen. The bieffect platinum-based MXene / MAX hybrid monomer catalyst prepared by the application can realize hydrogenation / dehydrogenation bieffect functions and improve the hydrogen purification rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen energy storage and transportation, and relates to a method for extracting high-purity hydrogen from hydrogen-natural gas mixed components. BACKGROUND

[0002] According to the current situation that the west of China is rich in hydrogen and the east of China is short of hydrogen, the existing natural gas pipeline is used for "sending hydrogen from the west to the east", which has high transportation efficiency. At present, the proportion of hydrogen in the natural gas pipeline can reach 24% (the international highest level). Meanwhile, this is also an important direction suitable for clean energy transportation and development in China. How to simply and efficiently extract hydrogen from hydrogen-mixed natural gas and safely transport it is a problem to be solved at present. The use of liquid organic molecular hydrogen carriers greatly avoids the safety problems and energy consumption of high-pressure hydrogen storage and low-temperature liquefaction. Catalytic hydrogenation of hydrogen in hydrogen-mixed natural gas to a liquid hydrogen carrier, and then catalytic dehydrogenation to release hydrogen, is a relatively mature method for transporting hydrogen at present. The hydrogenation technology can be industrialized, and the dehydrogenation is currently in the experimental stage. The catalyst used needs to have the functions of double-effect hydrogenation / dehydrogenation. The research on such recyclable catalysts needs to be further promoted. SUMMARY

[0003] The purpose of the application is to provide a method for extracting high-purity hydrogen from hydrogen-natural gas mixed components. The double-effect platinum-based MXene / MAX hybrid monomer catalyst prepared by the method can realize the functions of hydrogenation / dehydrogenation and improve the hydrogen purification rate.

[0004] The technical scheme adopted by the application is a method for extracting high-purity hydrogen from hydrogen-natural gas mixed components, which specifically includes the following steps:

[0005] Step 1, preparing a platinum-based MXene / MAX hybrid monomer catalyst;

[0006] Step 2, under the action of the catalyst obtained in step 1, hydrogenating the hydrogen-mixed natural gas and toluene to obtain methylcyclohexane and realize hydrogen storage;

[0007] Step 3, under the catalysis of the catalyst obtained in step 1, dehydrogenating the methylcyclohexane obtained in step 2 to obtain toluene and hydrogen.

[0008] The application also has the following characteristics:

[0009] The specific process of step 1 is as follows:

[0010] Step 1.1, preparing a LiF / HCl mixed solution;

[0011] Step 1.2, 0.5g-1g Ti3AlC2 MAX phase powder is added to the LiF / HCl mixed solution prepared in step 1.1, stirring at a speed of 350 rpm-550 rpm, etching for 24 h-36 h, after the reaction is completed, the reaction solution is poured into a centrifuge tube, washed with deionized water, centrifuged at a speed of 3500 rpm-5500 rpm for 5 min-15 min, the supernatant is discarded, and the precipitate is obtained;

[0012] Step 1.3, the solid MXene / MAX hybrid monomer catalyst carrier is prepared according to the precipitate obtained in step 1.2;

[0013] Step 1.4, 0.3g-0.5g of solid MXene / MAX hybrid monomer catalyst carrier is taken, 20 mL-40 mL of water is added, 6 mg-8 mg of H2PtCl6·6H2O is added, ultrasonic treatment is carried out for 30 min-60 min, and the mixture is dried at 60℃-80℃ for 12 h-24 h, then the mixture is reduced at a temperature of 200℃-500℃ under a H2 / Ar mixed gas for 3 h-5 h under a pressure of 0.1 MPa-0.13 MPa, to obtain a platinum-based MXene / MAX hybrid monomer catalyst.

[0014] In step 2, the hydrogenation reaction conditions of mixed hydrogen natural gas and toluene in the fixed bed reactor are as follows: the hydrogenation reaction temperature is 140℃-200℃, the hydrogenation reaction pressure is 1 MPa-6 MPa, and the hydrogenation reaction space velocity is 1 h -1 -7 h -1 .

[0015] In step 3, the dehydrogenation reaction conditions of methylcyclopropane in the fixed bed reactor are as follows: the dehydrogenation reaction temperature is 300℃-380℃, the dehydrogenation reaction pressure is 0.1 MPa-0.5 MPa, and the dehydrogenation reaction space velocity is 15 h -1 -20 h -1 .

[0016] The specific process of step 1.1 is as follows:

[0017] First, 1.2g / g MAX -1.6g / g MAX of LiF powder is weighed, and 15 mL / g-20 mL / g MAX of concentrated hydrochloric acid is weighed, and the LiF powder and concentrated hydrochloric acid are poured into a polytetrafluoroethylene bottle, and a magnetic stirrer is used to heat to 45℃-55℃, so that the LiF powder is fully dissolved in the hydrochloric acid to obtain a LiF / HCl mixed solution.

[0018] The specific process of step 1.3 is as follows:

[0019] The precipitate obtained in step 1.2 is dispersed in 100 mL-200 mL of deionized water, ultrasonic treatment is carried out in an ice water bath for 2 h-3 h, and then the dispersion is centrifuged for 10 min-60 min, the dark green upper layer dispersion MXene and the lower layer black precipitate MXene / MAX are freeze-dried for 24-48 h, and 10 wt%-50 wt% of the black precipitate MXene / MAX and MXene monolayer powder are taken to obtain a solid MXene / MAX hybrid monomer catalyst carrier.

[0020] The hydrogen-natural gas mixed component extraction high-purity hydrogen method provided by the application has the advantages that under the action of the double-effect platinum-based MXene catalyst, the hydrogen in the hydrogen-mixed natural gas is directly separated in the form of a liquid hydrogen carrier through two gas-liquid-gas cycles, and a higher hydrogen volume fraction of 99.9% is finally obtained. The catalyst hydrogenation and dehydrogenation cycles are good, the noble metal used is Pt which is lower in price than Ru, Rh, Ir and Pd, the etched MXene monolayer / multilayer sheet has a large specific surface area and is beneficial to the surface distribution of Pt, and the existence of the hybrid MXene / MAX structure is beneficial to the further dispersion of the surface distribution of Pt, preventing the poisoning and deactivation of Pt active sites in the reaction process. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a reaction schematic diagram for storing and releasing hydrogen in the hydrogen-natural gas mixed component extraction high-purity hydrogen method of the application;

[0022] Figure 2 It is a hydrogen volume fraction diagram of 10 h fixed-bed catalytic hydrogen-mixed natural gas after two cycles in Example 1 of the hydrogen-natural gas mixed component extraction high-purity hydrogen method of the application;

[0023] Figure 3 It is a gas instantaneous yield diagram of hydrogen H2, methane CH4, carbon monoxide CO, carbon dioxide CO2, ethylene, ethane, propylene and propane (ethylene and ethane are represented as C2, and propylene and propane are represented as C3) of 10 h fixed-bed catalytic hydrogen-mixed natural gas after two cycles in Example 1 of the hydrogen-natural gas mixed component extraction high-purity hydrogen method of the application;

[0024] Figure 4 It is a hydrogen volume fraction diagram of 10 h fixed-bed catalytic hydrogen-mixed natural gas after two cycles in Comparative Example 2 of the hydrogen-natural gas mixed component extraction high-purity hydrogen method of the application;

[0025] Figure 5A gas instantaneous yield graph of hydrogen, methane, carbon monoxide, carbon dioxide, ethylene, ethane, propylene, and propane (ethylene and ethane are represented as C2, and propylene and propane are represented as C3) after two cycles of the 10h fixed-bed catalytic mixed hydrogen natural gas obtained in Comparative Example 2 of the method for extracting high-purity hydrogen from a hydrogen-natural gas mixed component according to the present application;

[0026] Figure 6 An XRD graph of the solid 1 / 3 MXene / MAX hybrid monomer catalyst of Example 1 of the method for extracting high-purity hydrogen from a hydrogen-natural gas mixed component according to the present application, the solid 1 / 6 MXene catalyst of Comparative Example 2, and MAX. DETAILED DESCRIPTION

[0027] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The method for extracting high-purity hydrogen from a hydrogen-natural gas mixed component according to the present application has a preparation flow as shown in Figure 1 and specifically includes the following steps:

[0029] Step 1, preparing a platinum-based MXene / MAX hybrid monomer catalyst;

[0030] 1.2-1.6g / g MAX Lithium fluoride (LiF) powder, 15-20mL / g MAXConcentrated hydrochloric acid. LiF powder and concentrated hydrochloric acid were poured into a polytetrafluoroethylene bottle, heated to 45-55°C using a magnetic stirrer, and the LiF powder was fully dissolved in the hydrochloric acid (after stirring for 5-10 min). 0.5-1 g of Ti3AlC2 MAX phase powder (200-400 mesh) was slowly added (over 3-5 min) to the LiF / HCl mixed solution, and a large amount of bubbles were observed to emerge from the liquid, indicating that the reaction had begun. The etching was carried out at a stirring speed of (350-550) rpm for 24-36 h. After the reaction was completed, the reaction liquid was poured into a plastic centrifuge tube, washed with deionized water, and centrifuged at high speed (3500-5500 rpm) for 5-15 min. The supernatant was discarded, and deionized water was added again and centrifuged. The washing was repeated until the supernatant was neutral, and the supernatant was discarded. The precipitate was dispersed in 100-200 mL of deionized water and treated with ultrasonic waves (200-300 W) in an ice water bath for 2-3 h, and then the dispersion was centrifuged (4000-8000 rpm) for 10-60 min. The dark green upper layer of MXene and the black lower layer of MXene / MAX were freeze-dried for 24-48 h, and 10-50 wt% of the black precipitate MXene / MAX and MXene monolayer powder were taken to obtain a solid MXene / MAX hybrid monomer catalyst carrier. 0.3-0.5 g of the solid MXene / MAX hybrid monomer catalyst carrier was taken, 20-40 mL of water was added, 6-8 mg of H2PtCl6·6H2O was added, and the mixture was ultrasonicated for 30-60 min. The mixture was dried at 60-80°C for 12-24 h, and a platinum-based MXene / MAX hybrid monomer catalyst was obtained by reduction at a H2 / Ar mixed gas reduction temperature of 200-500°C for 3-5 h at a reduction pressure of 0.1-0.13 MPa;

[0031] Step 2: Toluene is hydrogenated with mixed hydrogen natural gas (hydrogen) in the presence of the catalyst obtained in step 1 to obtain methylcyclohexane, thereby storing hydrogen;

[0032] In step 2, the hydrogenation reaction of mixed hydrogen natural gas and toluene in the fixed bed reactor is carried out at a temperature of 140-200°C, a pressure of 1-6 MPa, and a space velocity of 1-7 h-1. -1

[0033] Step 3: Methylcyclohexane is dehydrogenated in the presence of the catalyst obtained in step 1 to obtain toluene and hydrogen, thereby obtaining hydrogen with a high volume percentage.

[0034] In step 3, the dehydrogenation reaction of methylcyclohexane in the fixed bed reactor is carried out at a temperature of 300-380°C, a pressure of 0.1-0.5 MPa, and a space velocity of 15-20 h-1.​-1 .

[0035] Example 1 (50wt% black precipitate MXene / MAX in step 1)

[0036] Take 1.2 g / g MAX Lithium fluoride powder, take 15 mL / g MAX Concentrated hydrochloric acid. Pour the LiF powder and concentrated hydrochloric acid into a polytetrafluoroethylene bottle, heat to 45°C using a magnetic stirrer, and fully dissolve the LiF powder in the hydrochloric acid (after stirring for 5 min). Slowly add (over a period of 3 min) 0.5 g of Ti3AlC2 MAX phase powder (200 mesh) to the LiF / HCl mixed solution, and observe a large amount of bubbles rising from the liquid, indicating the start of the reaction. Stir at a speed of (350 rpm) for 24 h. After the reaction is complete, pour the reaction liquid into a plastic centrifuge tube, wash with deionized water, centrifuge at high speed (3500 rpm) for 5 min, pour off the supernatant, and add deionized water again and centrifuge. Repeat the washing until the supernatant is neutral, and discard the supernatant. Disperse the precipitate in 100 mL of deionized water, ultrasonic (200 W) treat in an ice water bath for 2 h, and then centrifuge (5000 rpm) the dispersion for 1 h. Take the dark green upper layer of the dispersion MXene and the lower layer of the dark green MXene / MAX, freeze-dry for 24 h, and take 50wt% of the black precipitate MXene / MAX and MXene monolayer powder to obtain a solid MXene / MAX hybrid monomer catalyst carrier. Take 0.3 g of the solid MXene / MAX hybrid monomer catalyst carrier, add 20 mL of water, and add 6 mg of H2PtCl6·6H2O, ultrasonic for 30 min, and dry at 60°C for 12 h. The reduction temperature is 300°C, the reduction time is 5 h, and the reduction pressure is 0.1 MPa to obtain a platinum-based MXene / MAX hybrid monomer catalyst; in a fixed bed reactor, the conditions for the hydrogenation reaction of mixed hydrogen natural gas and toluene are: the hydrogenation reaction temperature is 180°C, the hydrogenation reaction pressure is 2 MPa, and the hydrogenation reaction space velocity is 7h -1 ; in a fixed bed reactor, the conditions for the dehydrogenation reaction of methylcyclopropane are: the dehydrogenation reaction temperature is 300°C, the dehydrogenation reaction pressure is 0.35 MPa, and the dehydrogenation reaction space velocity is 15h -1 .

[0037] Comparative Example 1 (0wt% black precipitate MXene / MAX in step 1)

[0038] Take 1.2 g / g MAX Lithium fluoride powder, take 15 mL / g MAXConcentrated hydrochloric acid. LiF powder and concentrated hydrochloric acid were poured into a polytetrafluoroethylene bottle, heated to 45°C using a magnetic stirrer, and the LiF powder was fully dissolved in the hydrochloric acid (after stirring for 5 min). 0.5 g of Ti3AlC2 MAX phase powder (200 mesh) was slowly added (over a period of 3 min) to the LiF / HCl mixed solution, and a large amount of bubbles were observed to emerge from the liquid, indicating that the reaction had begun. The etching was carried out at a stirring speed of (350 rpm) for 24 h. After the reaction was completed, the reaction liquid was poured into a plastic centrifuge tube, washed with deionized water, and centrifuged at high speed (3500 rpm) for 5 min, and the supernatant was poured out. After adding deionized water again, the centrifugation was repeated until the supernatant was neutral, and the supernatant was discarded. The precipitate was dispersed in 100 mL of deionized water, treated with ultrasonic waves (200 W) in an ice water bath for 2 h, and then the dispersion was treated with centrifugation (5000 rpm) for 1 h. The dark green upper layer of the dispersion, MXene, was obtained, and was freeze-dried for 24 h to obtain a solid MXene monomer catalyst carrier. 0.3 g of the solid MXene catalyst carrier was taken, 20 mL of water was added, 6 mg of H2PtCl6·6H2O was added, and ultrasonic treatment was carried out for 30 min, and the mixture was dried at 60°C for 12 h. The reduction temperature was 300°C, the reduction time was 5 h, and the reduction pressure was 0.1 MPa, to obtain a platinum-based MXene monomer catalyst. The conditions for the hydrogenation reaction of mixed hydrogen natural gas and toluene in a fixed bed reactor were as follows: the hydrogenation reaction temperature was 180°C, the hydrogenation reaction pressure was 2 MPa, and the hydrogenation reaction space velocity was 10 h -1 ; the conditions for the dehydrogenation reaction of methylcyclopropane in a fixed bed reactor were as follows: the dehydrogenation reaction temperature was 300°C, the dehydrogenation reaction pressure was 0.35 MPa, and the dehydrogenation reaction space velocity was 15 h -1 .

[0039] Comparative Example 2 (5 wt% black precipitated MXene / MAX was taken in step 1)

[0040] 1.2 g / g MAX Lithium fluoride powder, 15 mL / g MAXConcentrated hydrochloric acid. LiF powder and concentrated hydrochloric acid were poured into a polytetrafluoroethylene bottle, heated to 45°C using a magnetic stirrer, and the LiF powder was fully dissolved in the hydrochloric acid (after stirring for 5 min). 0.5 g of Ti3AlC2 MAX phase powder (200 mesh) was slowly added (over a period of 3 min) to the LiF / HCl mixed solution, and a large amount of bubbles were observed to emerge from the liquid, indicating the start of the reaction. The etching was carried out at a stirring speed of 350 rpm for 24 h. After the reaction was completed, the reaction liquid was poured into a plastic centrifuge tube, washed with deionized water, and centrifuged at high speed (3500 rpm) for 5 min, and the supernatant was discarded. The precipitate was dispersed in 100 mL of deionized water, treated with ultrasonic waves (200 W) in an ice water bath for 2 h, and then the dispersion was treated with centrifugation (5000 rpm) for 1 h. The dark green upper layer of the dispersion MXene and the lower layer of the black precipitate MXene / MAX were freeze-dried for 24 h, and 5 wt% of the black precipitate MXene / MAX and MXene monolayer powder were taken to obtain a solid MXene / MAX hybrid monomer catalyst carrier. 0.3 g of the solid MXene / MAX hybrid monomer catalyst carrier was taken, 20 mL of water was added, 6 mg of H2PtCl6·6H2O was added, and the mixture was ultrasonically treated for 30 min, and then dried at 60°C for 12 h. The reduction temperature was 300°C, the reduction time was 5 h, and the reduction pressure was 0.1 MPa, to obtain a platinum-based MXene / MAX hybrid monomer catalyst. The conditions for the hydrogenation reaction of mixed hydrogen natural gas and toluene in a fixed bed reactor were as follows: the hydrogenation reaction temperature was 180°C, the hydrogenation reaction pressure was 2 MPa, and the hydrogenation reaction space velocity was 10 h -1 ; the conditions for the dehydrogenation reaction of methylcyclopropane in a fixed bed reactor were as follows: the dehydrogenation reaction temperature was 300°C, the dehydrogenation reaction pressure was 0.35 MPa, and the dehydrogenation reaction space velocity was 15 h -1 .

[0041] Comparative Example 3 (75 wt% black precipitate MXene / MAX was taken in step 1)

[0042] 1.2 g / g MAX Lithium fluoride powder, 15 mL / g MAXConcentrated hydrochloric acid. LiF powder and concentrated hydrochloric acid were poured into a polytetrafluoroethylene bottle, heated to 45°C using a magnetic stirrer, and the LiF powder was fully dissolved in the hydrochloric acid (after stirring for 5 min). 0.5 g of Ti3AlC2 MAX phase powder (200 mesh) was slowly added (over a period of 3 min) to the LiF / HCl mixed solution, and a large amount of bubbles were observed to emerge from the liquid, indicating the start of the reaction. The etching was carried out at a stirring speed of 350 rpm for 24 h. After the reaction was completed, the reaction liquid was poured into a plastic centrifuge tube, washed with deionized water, and centrifuged at high speed (3500 rpm) for 5 min, and the supernatant was discarded. The precipitate was dispersed in 100 mL of deionized water, treated with ultrasonic waves (200 W) in an ice water bath for 2 h, and then the dispersion was treated with centrifugation (5000 rpm) for 1 h. The dark green upper layer dispersion MXene and the lower layer black precipitate MXene / MAX were freeze-dried for 24 h, and 75 wt% of the black precipitate MXene / MAX and MXene monolayer powder were taken to obtain a solid MXene / MAX hybrid monomer catalyst carrier. 0.3 g of the solid MXene / MAX hybrid monomer catalyst carrier was taken, 20 mL of water was added, 6 mg of H2PtCl6·6H2O was added, and ultrasonic treatment was carried out for 30 min, and then the mixture was dried at 60°C for 12 h. The reduction temperature was 300°C, the reduction time was 5 h, and the reduction pressure was 0.1 MPa, to obtain a platinum-based MXene / MAX hybrid monomer catalyst. The conditions for the hydrogenation reaction of mixed hydrogen natural gas and toluene in a fixed bed reactor were as follows: the hydrogenation reaction temperature was 180°C, the hydrogenation reaction pressure was 2 MPa, and the hydrogenation reaction space velocity was 10 h -1 ; the conditions for the dehydrogenation reaction of methyl cyclopropane in a fixed bed reactor were as follows: the dehydrogenation reaction temperature was 300°C, the dehydrogenation reaction pressure was 0.35 MPa, and the dehydrogenation reaction space velocity was 15 h -1 .

[0043] Comparative Example 4 (step 1 used sodium borohydride reduction method, 50 wt% black precipitate MXene / MAX was taken)

[0044] 1.2 g / g MAX lithium fluoride powder, 15 mL / g MAXConcentrated hydrochloric acid. LiF powder and concentrated hydrochloric acid were poured into a polytetrafluoroethylene bottle, heated to 45°C using a magnetic stirrer, and the LiF powder was fully dissolved in the hydrochloric acid (after stirring for 5 min). 0.5 g of Ti3AlC2 MAX phase powder (200 mesh) was slowly added (over a period of 3 min) to the LiF / HCl mixed solution, and a large amount of bubbles were observed to emerge from the liquid, indicating that the reaction had begun. The etching was carried out at a stirring speed of (350 rpm) for 24 h. After the reaction was completed, the reaction liquid was poured into a plastic centrifuge tube, washed with deionized water, and centrifuged at high speed (3500 rpm) for 5 min. The supernatant was poured off, and deionized water was added again and centrifuged. The washing was repeated until the supernatant was neutral, and the supernatant was discarded. The precipitate was dispersed in 100 mL of deionized water, treated with ultrasonic waves (200 W) in an ice water bath for 2 h, and then centrifuged (5000 rpm) for 1 h. The dark green upper layer of the dispersion MXene and the lower layer of the black precipitate MXene / MAX were freeze-dried for 24 h, and 50 wt% of the black precipitate MXene / MAX and MXene monolayer powder were taken to obtain a solid MXene / MAX hybrid monomer catalyst carrier. 0.3 g of the solid MXene / MAX hybrid monomer catalyst carrier was taken, 20 mL of water was added, a certain amount of sodium borohydride was added, 6 mg of H2PtCl6·6H2O was added, ultrasonic treatment was performed for 30 min, centrifugal washing was performed 3 times, and drying was performed at 60°C for 12 h to obtain a platinum-based MXene / MAX hybrid monomer catalyst; in a fixed bed reactor, the hydrogenation reaction conditions of mixed hydrogen natural gas and toluene were as follows: the hydrogenation reaction temperature was 180°C, the hydrogenation reaction pressure was 2 MPa, and the hydrogenation reaction space velocity was 10 h -1 ; in a fixed bed reactor, the dehydrogenation reaction conditions of methylcyclopropane were as follows: the dehydrogenation reaction temperature was 300°C, the dehydrogenation reaction pressure was 0.35 MPa, and the dehydrogenation reaction space velocity was 15 h -1 .

[0045] The hydrogen purity effects of the catalysts under different conditions after hydrogenation and dehydrogenation are compared in Table 1 below

[0046] Table 1

[0047]

[0048] From Table 1, it can be seen that for the hydrogen-reduced catalyst: the hydrogenation selectivity, dehydrogenation selectivity, and hydrogen volume percentage of Example 1 are the highest, and the hydrogen volume percentage reduction rate after 10 h of catalysis is the lowest. The hydrogenation selectivity, dehydrogenation selectivity, and hydrogen volume increase first and then decrease with the mass percentage of the black precipitate MXene / MAX taken, and the hydrogen volume percentage reduction rate after 10 h of catalysis decreases first and then increases. Compared with the hydrogen reduction method of Example 1, the sodium borohydride reduction method of Comparative Example 4 is better under the same preparation of the catalyst and experimental conditions.

[0049] Figure 2 The hydrogen volume fraction graph of the 10h fixed-bed catalytic mixed hydrogen natural gas after two cycles obtained by the method for extracting high-purity hydrogen from hydrogen-natural gas mixed components of the present application can obviously see that the volume fraction of hydrogen obtained by the final dehydrogenation is as high as 99.9%, and remains stable until it decreases by 0.01% after 10h, which indicates that the dehydrogenation effect of the catalyst in this example is good and the stability is high;

[0050] Figure 3 The gas instantaneous yield graph of hydrogen H2, methane CH4, carbon monoxide CO, carbon dioxide CO2, ethylene, ethane, propylene, propane (ethylene and ethane are represented as C2, and propylene and propane are represented as C3) after two cycles of the 10h fixed-bed catalytic mixed hydrogen natural gas obtained by the method for extracting high-purity hydrogen from hydrogen-natural gas mixed components of the present application can see that the instantaneous yield of the remaining gases except hydrogen approaches 0, and the instantaneous yield of hydrogen is the highest, which indicates that the dehydrogenation selectivity of the catalyst obtained in example 1 is good;

[0051] Figure 4 The hydrogen volume fraction graph of the 10h fixed-bed catalytic mixed hydrogen natural gas after two cycles obtained by the method for extracting high-purity hydrogen from hydrogen-natural gas mixed components of the present application can obviously see that the volume fraction of hydrogen obtained by the final dehydrogenation is as high as 99.9%, and remains stable until it decreases by 0.01% after 10h, which indicates that the dehydrogenation effect of the catalyst in this example is good and the stability is high;

[0052] Figure 5 The gas instantaneous yield graph of hydrogen H2, methane CH4, carbon monoxide CO, carbon dioxide CO2, ethylene, ethane, propylene, propane (ethylene and ethane are represented as C2, and propylene and propane are represented as C3) after two cycles of the 10h fixed-bed catalytic mixed hydrogen natural gas obtained by the method for extracting high-purity hydrogen from hydrogen-natural gas mixed components of the present application can see that the instantaneous yield of the remaining gases except hydrogen approaches 0, and the instantaneous yield of hydrogen is the highest, which indicates that the dehydrogenation selectivity of the catalyst obtained in example 1 is good;

[0053] Figure 6 The XRD graph of example 1 and comparison example 2 and MAX of the method for extracting high-purity hydrogen from hydrogen-natural gas mixed components of the present application can see that the MAX peak of example 1 exists obviously, and the MAX peak of comparison example 2 basically disappears, which indicates that the appropriate amount of MAX phase is beneficial to catalysis.

[0054] Example 2

[0055] Take 1.6g / g MAX Lithium fluoride powder, 20mL / g MAXConcentrated hydrochloric acid, LiF powder and concentrated hydrochloric acid were poured into a polytetrafluoroethylene bottle, heated to 55°C using a magnetic stirrer, and the LiF powder was fully dissolved in the hydrochloric acid (after stirring for 10 min). 1 g of Ti3AlC2 MAX phase powder (400 mesh) was slowly added (5 min during addition) to the LiF / HCl mixed solution, and a large amount of bubbles were observed to emerge from the liquid, indicating the start of the reaction. The etching was carried out at a stirring speed of (550 rpm) for 36 h. After the reaction was completed, the reaction liquid was poured into a plastic centrifuge tube, washed with deionized water, and centrifuged at high speed (5500 rpm) for 15 min, and the supernatant was poured out. After adding deionized water again, the centrifugation was repeated until the pH of the supernatant was neutral, and the supernatant was discarded. The precipitate was dispersed in 200 mL of deionized water, treated with ultrasonic waves (300 W) in an ice water bath for 3 h, and then the dispersion was treated with centrifugation (4000 rpm) for 10 min. The dark green upper layer dispersion MXene and the lower layer black precipitate MXene / MAX were freeze-dried for 48 h, and 10 wt% of the black precipitate MXene / MAX and MXene monolayer powder were taken to obtain a solid MXene / MAX hybrid monomer catalyst carrier. 0.5 g of the solid MXene / MAX hybrid monomer catalyst carrier was taken, 40 mL of water was added, 8 mg of H2PtCl6·6H2O was added, and ultrasonic treatment was carried out for 60 min. The sample was dried at 80°C for 24 h, and a platinum-based MXene / MAX hybrid monomer catalyst was obtained by reduction at a temperature of 500°C for 3 h under a reduction pressure of 0.13 MPa. The conditions for the hydrogenation reaction of mixed hydrogen natural gas and toluene in a fixed bed reactor were as follows: the temperature of the hydrogenation reaction was 140°C, the pressure of the hydrogenation reaction was 1 MPa, and the space velocity of the hydrogenation reaction was 5 h -1 The conditions for the dehydrogenation reaction of methyl cyclopropane in a fixed bed reactor were as follows: the temperature of the dehydrogenation reaction was 380°C, the pressure of the dehydrogenation reaction was 0.1 MPa, and the space velocity of the dehydrogenation reaction was 20 h -1 .

[0056] Example 3

[0057] 1.5 g / g MAX Lithium fluoride powder, 18 mL / g MAXConcentrated hydrochloric acid, LiF powder and concentrated hydrochloric acid were poured into a polytetrafluoroethylene bottle, heated to 50°C using a magnetic stirrer, and the LiF powder was fully dissolved in the hydrochloric acid (after stirring for 8 min). 0.8 g of Ti3AlC2 MAX phase powder (300 mesh) was slowly added (4 min during addition) to the LiF / HCl mixed solution, and a large amount of bubbles were observed to emerge from the liquid, indicating the start of the reaction. The solution was stirred at a speed of (450 rpm) for 30 h. After the reaction was completed, the reaction solution was poured into a plastic centrifuge tube, washed with deionized water, and centrifuged at high speed (4500 rpm) for 10 min, and the supernatant was poured out. After adding deionized water again, the supernatant was centrifuged again. The washing was repeated until the supernatant was neutral, and the supernatant was discarded. The precipitate was dispersed in 150 mL of deionized water, treated with ultrasonic waves (250 W) in an ice water bath for 2.5 h, and then the dispersion was treated with centrifugation (8000 rpm) for 40 min. The dark green upper layer dispersion MXene and the lower layer black precipitate MXene / MAX were freeze-dried for 36 h, and 25 wt% of the black precipitate MXene / MAX and MXene monolayer powder were taken to obtain a solid MXene / MAX hybrid monomer catalyst carrier. 0.4 g of the solid MXene / MAX hybrid monomer catalyst carrier was taken, 30 mL of water was added, 7 mg of H2PtCl6·6H2O was added, and ultrasonic treatment was performed for 40 min. The sample was dried at 70°C for 20 h, and a platinum-based MXene / MAX hybrid monomer catalyst was obtained by reduction at a temperature of 300°C for 4 h under a reduction pressure of 0.12 MPa. The conditions for the hydrogenation reaction of mixed hydrogen natural gas and toluene in a fixed bed reactor were as follows: the temperature of the hydrogenation reaction was 200°C, the pressure of the hydrogenation reaction was 6 MPa, and the space velocity of the hydrogenation reaction was 1 h -1 ; the conditions for the dehydrogenation reaction of methylcyclopropane in a fixed bed reactor were as follows: the temperature of the dehydrogenation reaction was 350°C, the pressure of the dehydrogenation reaction was 0.5 MPa, and the space velocity of the dehydrogenation reaction was 18 h -1 .

Claims

1. A method for extracting high-purity hydrogen from a hydrogen-natural gas mixture, characterized in that: Specifically, the steps include the following: Step 1, preparation of platinum-based MXene / MAX hybrid monomer catalyst; the specific process of step 1 is as follows: Step 1.1, preparing a LiF / HCl mixed solution; the specific process of step 1.1 is as follows: First weigh out 1.2 g / g MAX ~1.6 g / g MAX LiF powder, then measure 15 mL / g to 20 mL / g MAX Concentrated hydrochloric acid: Pour LiF powder and concentrated hydrochloric acid into a polytetrafluoroethylene bottle, heat to 45℃~55℃ using a magnetic stirrer to fully dissolve the LiF powder in the hydrochloric acid, and obtain a LiF / HCl mixed solution. Step 1.2: Add 0.5g to 1g of Ti3AlC2 MAX phase powder to the LiF / HCl mixed solution prepared in Step 1.1, stir at 350 rpm to 550 rpm, and etch for 24h to 36h. After the reaction is complete, pour the reaction solution into a centrifuge tube, wash with deionized water, centrifuge at 3500 rpm to 5500 rpm for 5min to 15min, discard the supernatant, add deionized water and centrifuge again, repeatedly wash until the pH of the supernatant is neutral, discard the supernatant to obtain the precipitate; Step 1.3: Prepare a solid MXene / MAX hybrid monomer catalyst support based on the precipitate obtained in Step 1.2; the specific process of Step 1.3 is as follows: The precipitate obtained in step 1.2 was dispersed in 100 mL to 200 mL of deionized water and ultrasonically treated in an ice-water bath for 2 to 3 hours. Then, the dispersion was centrifuged for 10 to 60 minutes. The dark green upper layer of dispersion MXene and the lower black precipitate MXene / MAX were freeze-dried for 24 to 48 hours. 10 wt% to 50 wt% of the black precipitate MXene / MAX and MXene monolayer powder were taken to obtain a solid MXene / MAX hybrid monomer catalyst support. The solid MXene / MAX hybrid monomer catalyst support was then freeze-dried for 24 to 48 hours. Step 1.4: Take 0.3 g to 0.5 g of solid MXene / MAX hybrid monomer catalyst support, add 20 mL to 40 mL of water, and add 6 mg to 8 mg of H2PtCl6. The platinum-based MXene / MAX hybrid monomer catalyst was obtained by ultrasonic treatment with 6H2O for 30-60 min, drying at 60-80℃ for 12-24 h, reduction with H2 / Ar mixed gas at 200-500℃ for 3-5 h, and reduction pressure of 0.1-0.13 MPa. Step 2: Under the action of the catalyst obtained in Step 1, the mixed hydrogen natural gas and toluene are hydrogenated to obtain methylcyclohexane, thereby achieving hydrogen storage. In Step 2, the hydrogenation reaction conditions for the mixed hydrogen natural gas and toluene in the fixed-bed reactor are: a hydrogenation reaction temperature of 140℃~200℃, a hydrogenation reaction pressure of 1MPa~6MPa, and a hydrogenation reaction space velocity of 1 h⁻¹. -1 ~7 h -1 ; Step 3: Under the catalysis of the catalyst obtained in Step 1, the methylcyclohexane obtained in Step 2 undergoes a dehydrogenation reaction to yield toluene and hydrogen. In Step 3, the conditions for the methylcyclomethane dehydrogenation reaction in the fixed-bed reactor are: a dehydrogenation reaction temperature of 300℃~380℃, a dehydrogenation reaction pressure of 0.1 MPa~0.5 MPa, and a dehydrogenation reaction space velocity of 15 h⁻¹. -1 ~20h -1 .

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