Process and system for hydrogen production and carbon production by methanol cracking

Abstract

The application relates to the hydrogen energy preparation technical field, in particular to a methanol cracking hydrogen production carbon process and system, the methanol cracking hydrogen production carbon process comprises the following steps: a, preparing methanol gas; b, methanol cracking is carried out through a catalyst system: under an argon atmosphere, the catalyst system is heated to a predetermined temperature, the methanol gas is introduced, and methanol cracking hydrogen production carbon is carried out; the catalyst system comprises an alloy catalyst and a modified metal oxide catalyst; c, product collection: collecting hydrogen and carbon material obtained by cracking. The application provides a methanol cracking hydrogen production carbon process and system, so as to solve the problems of insufficient catalyst activity and selectivity, large reactor energy consumption and high investment.

Description

Technical Field

[0001] This application relates to the field of hydrogen production technology, and in particular to a process and system for producing hydrogen and carbon from methanol through cracking. Background Technology

[0002] With the widespread application of hydrogen energy in fuel cells, industrial synthesis, and energy storage, efficient, economical, and low-carbon hydrogen production has become a research hotspot. Methanol (CH3OH), as a liquid carbon-based small-molecule fuel, is widely regarded as an ideal raw material for hydrogen production due to its wide availability, convenient storage and transportation, high hydrogen content, and ease of handling at ambient temperature and pressure. Methanol cracking (direct cracking or catalytic cracking) generates hydrogen and carbon monoxide by thermal / catalytically breaking down methanol molecules (main reaction: CH3OH→CO+2H2), or by generating syngas, primarily H2, through reforming under aqueous / oxidant conditions. Compared to direct natural gas reforming or water electrolysis for hydrogen production, methanol cracking has potential advantages in terms of ambient pressure and low-temperature start-up, energy consumption, and system scale flexibility, making it suitable for distributed hydrogen production, portable hydrogen sources, and co-processing with methanol-based fuel cells.

[0003] Current methanol cracking technologies still face several technical bottlenecks: First, the catalyst activity and selectivity are insufficient, especially in suppressing methanol dehydration, methanol dehydrogenation, and secondary side reactions (such as methanol byproduct polymerization and carbon deposition). Second, the catalyst's thermal stability and resistance to carbon deposition and sulfur poisoning are limited, leading to frequent regeneration or replacement during long-term operation. Third, reactor thermal management is challenging—methanol cracking / reforming is an endothermic or exothermic process (depending on the process), requiring efficient heat transfer, rapid heating, and local overheating / cooling control to maintain the catalyst within the target temperature range at high throughput. Fourth, the online separation, purification, and integrated system integration of products (H2 / CO) still need optimization to reduce energy consumption and equipment investment. In summary, developing highly active, highly selective, long-life, and easily regenerable methanol cracking catalysts, along with corresponding efficient, easily scalable reactor designs suitable for distributed / modular applications, are key technical issues for achieving the industrialization of efficient methanol-to-hydrogen production. Summary of the Invention

[0004] This application provides a process and system for methanol cracking to produce hydrogen and carbon, in order to solve the problems mentioned in the background art.

[0005] In a first aspect, a process for producing hydrogen and carbon from methanol through cracking is provided, which includes the following steps:

[0006] a. Preparation of methanol gas: Methanol liquid is continuously heated to 68~75℃ to vaporize the methanol liquid and obtain methanol gas;

[0007] b. Methanol cracking via a catalyst system: Under an argon atmosphere, the catalyst system is heated to a predetermined temperature, and methanol gas is introduced to carry out methanol cracking to produce hydrogen and carbon.

[0008] The catalyst system includes an alloy catalyst and a modified metal oxide catalyst, wherein the mass ratio of the alloy catalyst to the modified metal oxide catalyst is (4~4.5):1, and the predetermined temperature is 600~1000℃.

[0009] c. Product collection: Collect the hydrogen and carbon materials obtained from the pyrolysis;

[0010] The preparation method of the alloy catalyst includes the following steps:

[0011] S101. After cleaning and activating the metal particles, dry them;

[0012] The metal particles comprise a primary metal and a secondary metal, wherein the primary metal is selected from Bi, and the secondary metal is selected from at least one of Co, Mn, Cu, Fe, and Ni.

[0013] The molar ratio of the secondary metal to the primary metal is (3~4):6;

[0014] S102. Under an argon protective atmosphere, the secondary metal is heated to 1400~1600℃ by electric arc to melt and obtain an alloy ingot. After cooling, it is placed in a furnace together with Bi, argon is added again, and it is heated to 780~800℃ for melting. Modifier is added so that Bi and the alloy ingot are co-melted. After annealing, an alloy catalyst is obtained.

[0015] The modifier is selected from lithium oxalate or yttrium carbonate, and the amount of the modifier added is 4 to 6% of the mass of Bi.

[0016] Preferably, step S101 includes the following steps:

[0017] Using carbon cloth as a substrate, the metal was ultrasonically cleaned sequentially with acetone and ethanol. The cleaned metal was then activated by immersion in dilute hydrochloric acid solution, followed by rinsing with deionized water and drying at 110~120℃.

[0018] Preferably, in step S102, the annealing operation includes the following steps:

[0019] The alloy obtained by eutectic melting Bi with an alloy ingot was sealed in a vacuum-sealed quartz ampoule and annealed at 280-300℃ for 8-10 hours to obtain the alloy catalyst.

[0020] Preferably, the preparation method of the modified metal oxide catalyst includes the following steps:

[0021] S201. Disperse the metal oxide in deionized water, sonicate, add hydroxyethyl cellulose, stir, filter and dry, and calcine at 420~450℃ for 1~2h to obtain the pretreated carrier; the amount of hydroxyethyl cellulose added is 1~2% of the mass of the metal oxide;

[0022] S202. The pretreated carrier is immersed in a suspension modification liquid, stirred and allowed to stand at room temperature for 10-12 hours, dried and then calcined at 600-700℃ for 2-3 hours under an argon atmosphere to obtain the modified carrier.

[0023] The preparation method of the suspension modified liquid is as follows: carbon nitride and molybdenum disulfide are mixed at a mass ratio of (2~3):1, anhydrous ethanol is added, and ultrasonic dispersion is carried out for 40~60 min to obtain the suspension modified liquid;

[0024] S203. The modified support is impregnated in a 0.5 mol / L lithium oxalate solution, stirred for 2-3 h, filtered and dried, calcined at 500-600℃ for 1.5-2 h, and cooled to obtain the modified metal oxide catalyst.

[0025] Preferably, before impregnating with the lithium oxalate solution, step S203 further includes the following step:

[0026] Add sepiolite and mix and grind it with the modified carrier. Add 5 wt% microcrystalline cellulose suspension, stir and filter.

[0027] The amount of sepiolite added is 4-5% of the mass of the modified carrier, and the amount of microcrystalline cellulose suspension added is 40-50% of the mass of the modified carrier.

[0028] Preferably, the metal oxide is selected from CeO2, La2O3, ZnO or CuO.

[0029] Secondly, a methanol cracking system for hydrogen and carbon production is provided, the system comprising:

[0030] Storage tank and heating device;

[0031] The reaction apparatus includes a heating device connected to the reaction apparatus via an insulated pipe, a dispersion component at the bottom of the reaction apparatus, and an outlet on the side wall of the reaction apparatus.

[0032] A pressure swing adsorption device, which is connected to the reaction device.

[0033] Preferably, the dispersion component includes a conduit and an aeration plate. The conduit is connected to an insulated pipe and runs along the direction of methanol gas transport. The aeration plate is located at the end of the conduit and at the bottom of the reaction device. The aeration plate discharges methanol gas in the form of bubbles, which rise and react with the catalyst system in a cracking reaction.

[0034] The rotational speed of the aeration disc is 100~500 r / min.

[0035] Preferably, the reaction device is provided with rotating blades, and the rotating blades are flush with the outlet.

[0036] Preferably, the heating device is equipped with a sensor;

[0037] The insulated pipe is equipped with an elastic gas collection bag and a flow meter; along the conveying direction of the insulated pipe, a pressure detection device is installed at the front end and the rear end of the flow meter.

[0038] The beneficial effects of the technical solution provided in this application include:

[0039] (1) This application provides a process for methanol cracking to produce hydrogen and carbon, which uses molten metal as the reaction medium and combines it with a highly dispersed modified metal oxide catalyst to form a composite catalyst system. This not only provides a highly active reaction interface, but also effectively avoids the deactivation problem caused by carbon deposition and sintering of traditional solid catalysts through the fluidity and thermal stability of liquid metal.

[0040] (2) The process and system provided in this application realize in-situ separation of the reaction and carbon products, supporting continuous production. Utilizing the low density of carbon products and their ability to float on the surface of molten metal, a rotating carbon scraping mechanism enables real-time collection of carbon materials, solving the problem of carbon buildup and blockage in traditional fixed-bed reactors, which necessitates shutdown for carbon removal. This allows the reaction unit to operate continuously, significantly improving process stability and production efficiency, and providing a feasible path for large-scale hydrogen production and co-production of carbon materials.

[0041] (3) The process and supporting system provided in this application are coupled with solar heating, which reduces energy consumption and improves the greenness of the process. The entire device system uses concentrated solar energy as the main heat source for methanol gasification, molten metal heating and reaction heat preservation, which significantly reduces the consumption of external electricity or fossil fuels; combined with the recycling cracking of unreacted methanol in the tail gas and the centralized treatment of CO / CO2, the overall process has low carbon emissions, which is in line with the development direction of green hydrogen energy;

[0042] (4) The process and system provided in this application can simultaneously obtain high-purity hydrogen and structurally controllable carbon materials, thus improving economic efficiency. The hydrogen generated by the reaction can be purified by PSA adsorption to obtain high-purity hydrogen products; at the same time, by adjusting the alloy composition in the alloy catalyst, the type of metal oxide in the modified metal oxide catalyst, and the reaction temperature and gas flow rate (reaction set temperature 600~1000℃, methanol gas flow rate 3~8 L / min), the morphology and thickness of the obtained carbon materials can be controlled, realizing the high added value utilization of carbon nanomaterials and enhancing the economic competitiveness of the overall process. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A schematic diagram of the process for achieving methanol cracking to produce hydrogen and carbon, provided in this application;

[0045] Figure 2 A flowchart illustrating the preparation of the alloy catalyst for the process of methanol cracking to produce hydrogen and carbon, as provided in this application.

[0046] Figure 3 A flowchart illustrating the preparation of the modified metal oxide catalyst for the process of methanol cracking to produce hydrogen and carbon, provided in this application.

[0047] Figure 4 The images show the characterization of the molten catalyst systems prepared in Examples 1-4 of this application after cooling using a scanning electron microscope (SEM). Figure 4 (a) is the SEM image of Example 1. Figure 4 (b) is the SEM image of Example 2. Figure 4 (c) is the SEM image of Example 3. Figure 4 (d) is the SEM image of Example 4;

[0048] Figure 5 Raman spectroscopy of the carbon products obtained in Examples 1-4 provided in this application;

[0049] Figure 6 Raman diagrams of the carbon products obtained from Comparative Examples 1 to 7 provided for this application.

[0050] In the diagram: 1. Storage tank; 2. Heating device; 21. Sensor; 3. Insulated pipe; 31. Elastic gas collection bag; 32. Flow meter; 33. First pressure detection device; 34. Second pressure detection device; 4. Reaction device; 41. Outlet; 42. Rotating blade; 5. Conduit; 6. Aeration disc; 7. Arched solar panel. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] See Figures 1-6 As shown, this application provides a process and system for methanol cracking to produce hydrogen and carbon.

[0053] Example 1

[0054] Based on the methanol cracking hydrogen-to-carbon process provided in this application, the methanol cracking hydrogen-to-carbon process provided in this embodiment includes the following steps:

[0055] a. Preparation of methanol gas: Using a pump, liquid methanol is transported from storage tank 1 into heating device 2. The methanol is continuously heated to 70°C by heating device 2 to vaporize the liquid methanol and obtain methanol gas.

[0056] b. Methanol cracking via a catalyst system: The alloy catalyst is added to the reaction device 4, and argon gas is continuously introduced into the reaction device 4 as a protective gas. When the reaction device 4 reaches the predetermined temperature of 800℃, it provides a molten medium for the reaction and maintains a stable reaction temperature. The alloy catalyst in the reaction device 4 is heated and melted. The modified metal oxide catalyst is added to the molten alloy catalyst (the mass ratio of alloy catalyst to modified metal oxide catalyst is 4.5:1). The argon gas is stopped, and methanol gas is transported into the reaction device 4 through the heat-insulating pipe 3 at a rate of 5L / min. Methanol is cracked to produce hydrogen and carbon through the catalyst system.

[0057] c. Product Collection: Collect the hydrogen and carbon materials obtained from the cracking. Specifically, the hydrogen is separated and collected using a PSA pressure swing adsorption device, while other gases are discharged. The carbon materials are collected through outlet 41 on the reaction device 4.

[0058] Heating device 2 is connected to a PSA (Pressure Swing Adsorption) unit, which separates the mixed gas after the reaction. The separated hydrogen is collected and stored, while the small amount of oxygen produced as a byproduct is directly discharged to prevent oxidation reactions with the products in subsequent reactions in reaction device 4. Unreacted methanol is reintroduced into the molten catalyst system of reaction device 4 for catalytic cracking. Byproduct gases such as carbon monoxide and carbon dioxide are introduced into a CO2 reactor. x Processing devices reduce carbon emissions.

[0059] During this process, some solid carbon is generated in reaction device 4. Due to its light weight, the solid carbon rises with the gas to the surface of the molten catalyst system. The carbon floating on the surface of the molten catalyst system accumulates continuously as the reaction continues. When the carbon accumulates to a certain height, if it is not dealt with in time, the carbon material will sinter with the metal or even block reaction device 4. Figure 1 As shown, the rotating blade 42 is set at the same height as the outlet 41. At this time, the carbon product is swept into the carbon storage bin through the outlet 41 by the rotating blade 42 for collection, and then carbon material is obtained, so that the reaction can continue for a long time.

[0060] This embodiment uses concentrated solar energy to power the decomposition reaction. When solar energy is abundant, the arched solar panels 7 collect heat on the reaction device 4 to provide energy for the reaction.

[0061] In this embodiment, the catalyst system includes an alloy catalyst and a modified metal oxide catalyst, wherein the preparation method of the alloy catalyst is as follows:

[0062] S101. Bi-Co-Cu three-phase alloy catalyst was prepared by selecting three metals: Bi, Co, and Cu. 20g of Bi, 1.88g of Co, and 2.04g of Cu metal particles were weighed. Bi, Co, and Cu metals were ultrasonically cleaned with acetone and ethanol in sequence to remove organic contaminants on the surface. The cleaned metals were activated by immersion in 1mol / L dilute hydrochloric acid solution for 30min, then rinsed with deionized water and dried at 120℃.

[0063] S102. Place high-melting-point Co and Cu into a water-cooled copper crucible and heat it to 1500°C under an argon protective atmosphere using an electric arc to fully melt and synthesize a uniform Cu-Co alloy ingot. After cooling, put it into a furnace together with Bi, fill it with argon again, heat it to 800°C to melt, and add 1g of yttrium carbonate so that Bi and the alloy ingot can be melted together.

[0064] The alloy obtained by co-melting Bi with alloy ingots was sealed in a vacuum-sealed quartz ampoule and annealed at 300°C for 9 hours to allow the phases to reach equilibrium, thus obtaining the alloy catalyst.

[0065] The preparation method of modified metal oxide catalyst is as follows:

[0066] S201. Disperse 15g of metal oxide CeO2 into 150g of deionized water (liquid-solid ratio 10:1), add 0.2g of hydroxyethyl cellulose, stir for 1h, filter, dry at 110℃ for 3h, and then calcine in argon at 430℃ for 1.5h to obtain the pretreated carrier.

[0067] S202. The pretreated carrier is immersed in a suspension modification liquid of equal volume, stirred and then allowed to stand at room temperature (25℃) for 12h. After drying, it is calcined in argon atmosphere at 650℃ for 2.5h to obtain the modified carrier.

[0068] The preparation method of the suspension modified liquid is as follows: 1g of carbon nitride and 0.5g of molybdenum disulfide are mixed, 30mL of anhydrous ethanol is added, and the mixture is ultrasonically dispersed for 50min to form a suspension modified liquid.

[0069] S203. Mix and grind 12g of modified support with 0.6g of sepiolite, add 6g of 5wt% microcrystalline cellulose suspension, stir and filter, then impregnate the filtered material in 0.5mol / L lithium oxalate solution (liquid-solid ratio 15:1), stir for 3h, filter, dry at 110℃, calcine at 550℃ for 2h, and cool to obtain modified metal oxide catalyst.

[0070] The method for preparing CeO2 in this embodiment is as follows:

[0071] Cerium nitrate Ce(NO3)3 was dissolved in deionized water to prepare a 1 mol / L solution. Sodium hydroxide was added to adjust the pH to 3, making the solution weakly acidic. Oxalic acid H2C2O4 solution was slowly added dropwise, and a double displacement reaction occurred to form a yellow precipitate of cerium oxalate.

[0072] The precipitate was filtered, washed to remove impurity ions, and dried at 110°C. The dried cerium oxalate was then calcined at 900°C for 2 hours to decompose it into CeO2 and remove residual carbon, finally yielding pure cerium oxide.

[0073] Example 2

[0074] The difference between this embodiment and embodiment 1 is that in the process steps of methanol cracking to produce hydrogen and carbon provided in this embodiment, the heating temperature of the heating device 2 in step a is 68°C, the predetermined temperature of the reaction device 4 in step b is 600°C, the flow rate of methanol gas into the reaction device 4 is 3L / min, and the rotation speed of the aeration plate is 500r / min.

[0075] Furthermore, in this embodiment, the catalyst system includes an alloy catalyst and a modified metal oxide catalyst, with a mass ratio of alloy catalyst to modified metal oxide catalyst of 4.5:1. The preparation method of the alloy catalyst is as follows:

[0076] S101. Bi-Co-Ni-Cu four-phase alloy catalyst was prepared by selecting four metals: Bi, Co, Ni, and Cu. 20g of Bi, 1.26g of Co, 1.26g of Ni, and 1.36g of Cu metal particles were weighed. Bi, Co, Ni, and Cu metals were ultrasonically cleaned with acetone and ethanol in sequence with carbon cloth as substrate to remove organic contaminants on the surface. The cleaned metals were activated by immersion in 1mol / L dilute hydrochloric acid solution for 30min, then rinsed with deionized water and dried at 110℃.

[0077] S102. Place high-melting-point Co, Ni and Cu into a water-cooled copper crucible and heat it to 1600℃ under an argon protective atmosphere using an electric arc to fully melt and synthesize a homogeneous Cu-Ni-Co alloy ingot; after cooling, put it into a furnace together with Bi, fill it with argon again, heat it to 790℃ for melting, and add 1.2g of yttrium carbonate to make Bi and the alloy ingot melt together.

[0078] The alloy obtained by eutectic melting Bi with alloy ingots was sealed in a vacuum-sealed quartz ampoule and annealed at 280°C for 10 hours to allow the phases to reach equilibrium, thus obtaining the alloy catalyst.

[0079] The preparation method of modified metal oxide catalyst is as follows:

[0080] S201. Disperse 18g of metal oxide La2O3 into 180g of deionized water, add 0.18g of hydroxyethyl cellulose, stir for 1h, filter, dry at 110℃ for 3h, and then calcine in argon at 420℃ for 2h to obtain the pretreated carrier.

[0081] S202. The pretreated carrier is immersed in a suspension modification liquid of equal volume, stirred and then allowed to stand at room temperature (25℃) for 11h. After drying, it is calcined at 600℃ for 3h under argon atmosphere to obtain the modified carrier.

[0082] The preparation method of the suspension modified liquid is as follows: 0.9g carbon nitride and 0.3g molybdenum disulfide are mixed, 24mL of anhydrous ethanol is added, and the mixture is ultrasonically dispersed for 40min to form a suspension modified liquid.

[0083] S203. Mix and grind 14g of modified support with 0.56g of sepiolite, add 5.6g of microcrystalline cellulose suspension with a concentration of 5wt%, stir and filter. Then, impregnate the filtered material in a 0.5mol / L lithium oxalate solution (liquid-solid ratio 15:1), stir for 2h, filter, dry at 110℃, calcine at 500℃ for 2h, and cool to obtain the modified metal oxide catalyst.

[0084] Example 3

[0085] The difference between this embodiment and embodiment 1 is that in the process steps of methanol cracking to produce hydrogen and carbon provided in this embodiment, the heating temperature of the heating device 2 in step a is 75°C, the predetermined temperature of the reaction device 4 in step b is 1000°C, the flow rate of methanol gas into the reaction device 4 is 7L / min, and the rotation speed of the aeration plate is 200r / min.

[0086] Furthermore, in this embodiment, the catalyst system includes an alloy catalyst and a modified metal oxide catalyst, with a mass ratio of alloy catalyst to modified metal oxide catalyst of 4:1. The preparation method of the alloy catalyst is as follows:

[0087] S101. Bi-Mn-Fe three-phase alloy catalyst was prepared by selecting three metals: Bi, Mn, and Fe. 20g of Bi, 1.32g of Mn, and 1.34g of Fe metal particles were weighed. The Bi, Mn, and Fe metals were ultrasonically cleaned with acetone and ethanol in sequence to remove organic contaminants on the surface. The cleaned metals were activated by immersion in 1mol / L dilute hydrochloric acid solution for 30min, then rinsed with deionized water and dried at 120℃.

[0088] S102. Place high-melting-point Mn and Fe into a water-cooled copper crucible and heat it to 1600℃ under an argon protective atmosphere using an electric arc to fully melt and synthesize a uniform Mn-Fe alloy ingot. After cooling, put it into a furnace together with Bi, fill it with argon again, heat it to 780℃ for melting, and add 0.8g of lithium oxalate to make Bi and alloy ingots melt together.

[0089] The alloy obtained by eutectic melting Bi with alloy ingots was sealed in a vacuum-sealed quartz ampoule and annealed at 300°C for 8 hours to allow the phases to reach equilibrium, thus obtaining the alloy catalyst.

[0090] The preparation method of modified metal oxide catalyst is as follows:

[0091] S201. Disperse 20g of metal oxide CuO into 200g of deionized water, add 0.4g of hydroxyethyl cellulose, stir for 1h, filter, dry at 110℃ for 3h, and then calcine in argon at 450℃ for 1h to obtain the pretreated carrier.

[0092] S202. The pretreated carrier is immersed in a suspension modification liquid of equal volume, stirred and then allowed to stand at room temperature (25℃) for 10h. After drying, it is calcined at 700℃ for 2h under argon atmosphere to obtain the modified carrier.

[0093] The preparation method of the suspension modified liquid is as follows: 1g of carbon nitride and 0.5g of molybdenum disulfide are mixed, 30mL of anhydrous ethanol is added, and the mixture is ultrasonically dispersed for 6min to form a suspension modified liquid.

[0094] S203. 16g of modified support was impregnated in a 0.5mol / L lithium oxalate solution (liquid-solid ratio 15:1), stirred for 2h, filtered, dried at 110℃, calcined at 600℃ for 1.5h, and cooled to obtain the modified metal oxide catalyst.

[0095] Example 4

[0096] The difference from Example 1 is that in this example, in the process steps of methanol cracking to produce hydrogen and carbon, the flow rate of methanol gas entering the reaction device 4 in step b is 8 L / min, and the rotation speed of the aeration disc is 100 r / min.

[0097] In this embodiment, the catalyst system includes an alloy catalyst and a modified metal oxide catalyst, with a mass ratio of the alloy catalyst to the modified metal oxide catalyst of 4:1.

[0098] In this embodiment, during the preparation of the alloy catalyst, S101 selects two metals, Bi and Co, to prepare a Bi-Co biphase alloy catalyst, wherein the mass of Bi is 20g and the mass of Co is 3.75g; the remaining operations are the same as in Example 1.

[0099] Furthermore, in the method for preparing the modified metal oxide catalyst, the metal oxide is selected from ZnO; the remaining operations are consistent with those in Example 1.

[0100] Comparative Example 1

[0101] The difference from Example 1 is that the modified metal oxide catalyst was replaced with CeO2.

[0102] Comparative Example 2

[0103] The difference from Example 1 is that no modified metal oxide catalyst is used.

[0104] Comparative Example 3

[0105] The difference from Example 1 is that no alloy catalyst is used.

[0106] Comparative Example 4

[0107] The difference from Example 1 is that the modified metal oxide catalyst is fixed on the inner wall of the reaction device 4 and is not directly added to the molten alloy catalyst.

[0108] Comparative Example 5

[0109] The difference from Example 1 is that the rotation of the aeration disc 6 is stopped, and the aeration is achieved solely by the natural rise of air bubbles.

[0110] Comparative Example 6

[0111] The difference from Example 1 is that the aeration plate 6 is not used, and methanol gas is directly introduced as large bubbles.

[0112] Comparative Example 7

[0113] The difference from Example 1 is that no carbon scraping is performed.

[0114] The methanol cracking process for hydrogen production and carbon production provided in the examples and comparative examples was tested.

[0115] See Table 1 for the test results of methanol cracking rate, catalyst system loss (within 24 hours), and hydrogen selectivity.

[0116] Table 1

[0117]

[0118] In Table 1, the catalyst loss rate is calculated as follows: After 24 hours of reaction, the residual catalyst is collected, dried, weighed, and the relative mass loss rate is calculated and used as the catalyst loss rate.

[0119]

[0120] See Table 2 for further details, which shows the test results for C production (within 24 hours), carbon product thickness, and catalyst system deactivation time.

[0121] Table 2

[0122]

[0123] In Table 2, the method for testing C yield within 24 hours is as follows: after reacting for 24 hours, collect the solid carbon product, dry it at 105℃ to constant weight, and weigh it to obtain the C yield.

[0124] The carbon product thickness test method is as follows: the average thickness of 500 carbon particles is statistically analyzed using a transmission electron microscope (TEM) to obtain the carbon product thickness.

[0125] In Table 2, the time point at which the methanol cracking rate drops to 70% of the initial value is defined as the deactivation time.

[0126] The catalyst system in Example 3 had a high loss rate, presumably because the predetermined temperature of the reaction device 4 was too high (1000°C). The high temperature intensified metal volatilization and carbon encapsulation. Although the deactivation time of the catalyst system was long (>100h), the operating cost was higher from the perspective of loss, and the hydrogen selectivity was also reduced.

[0127] The catalyst system in Example 4 consisted of an alloy catalyst and a modified metal oxide catalyst in a 1:1 mass ratio, with ZnO used as the metal oxide in the modified metal oxide catalyst. Compared to Example 1, the methanol cracking rate and hydrogen selectivity decreased. This indicates that a 2:1 mass ratio of alloy catalyst to modified metal oxide catalyst is more conducive to the exposure of active sites, and the oxygen vacancies in CeO2 are more conducive to suppressing side reactions. However, the cracking rate decreased in Example 2, indicating that the reaction was limited at low temperatures (set temperature 600℃), and the methanol conversion was incomplete.

[0128] From the perspective of catalyst deactivation time, the catalyst system composed of alloy catalyst and modified metal oxide catalyst can effectively inhibit sintering and carbon deposition, and improve stability. In Comparative Example 2, no modified metal oxide catalyst was added, and carbon rapidly deposited on the surface of the alloy catalyst, encapsulating the active sites. In Comparative Example 3, only modified metal oxide catalyst was used, without molten medium protection, resulting in severe high-temperature sintering, and the catalyst system deactivation time was only 13 hours. Comparative Example 7 did not undergo carbon scraping treatment, and carbon covered the surface of the molten metal, preventing the active sites from being continuously exposed, thus reducing the deactivation time.

[0129] Furthermore, as can be seen from Comparative Examples 5 and 6, the aeration disc can ensure sufficient contact between methanol and the catalyst system and uniform heating of methanol and the catalyst system. For example, the carbon yield of Comparative Example 6 was only 0.43 kg, but the thickness reached 84 nm, indicating that insufficient mass transfer led to uneven carbon growth and easy formation of amorphous thick carbon. In contrast, Comparative Example 1 used only CeO2, and its carbon yield was 0.50 kg with a thickness of 50 nm, indicating that the alloy catalyst can effectively induce ordered carbon growth.

[0130] In the embodiments provided in this application, the prepared alloy catalyst uses lithium oxalate / yttrium carbonate as a modifier, and introduces Li... + and Y 3+ Ions are used to optimize the microstructure and catalytic active sites of the alloy catalyst, enhancing its adsorption-dissociation ability for methanol molecules, promoting CO bond breaking, and improving its anti-sintering performance and extending its service life. The modified metal oxide catalyst is modified for anti-carbon deposition through carbon nitride (C3N4) and molybdenum disulfide. C3N4 has a graphite-like structure that can induce ordered carbon growth (such as carbon nanotubes), while MoS2 provides sulfur active sites and inhibits excessive carbon chain growth. Furthermore, sepiolite and microcrystalline cellulose are added to enhance its resistance to sulfur poisoning. During calcination, microcrystalline cellulose decomposes and volatilizes, forming a porous structure in the sepiolite and metal oxides and adsorbing sulfur substances. Simultaneously, its surface hydroxyl groups form chemical bonds with sulfur, achieving chemisorption.

[0131] See Figure 4 As shown, these are scanning electron microscope (SEM) images of the molten catalyst systems (hereinafter referred to as samples) prepared in Examples 1-4 after cooling. Figure 4(a) is Example 1. Figure 4 (b) is Example 2. Figure 4 (c) is Example 3. Figure 4 (d) is Example 4. It can be seen that each sample exhibits a micron-scale blocky or sheet-like framework structure, with varying degrees of fine particles adhering to their surfaces, forming a relatively obvious multi-level composite morphology. Simultaneously, some samples show obvious lamellar stacking and wrinkled structures with certain gaps between layers; others exhibit rough-surfaced blocky aggregates, accompanied by fractures, cracks, and particle adhesion. The above results indicate that the catalyst system obtained in this application has high surface roughness and abundant edge defect sites, providing more active interfaces, which is beneficial for the adsorption, activation, and subsequent reactions of reactants during methanol cracking.

[0132] See Figure 5 and Figure 6 The figures shown are Raman spectral data of the carbon materials prepared in the examples and comparative examples, respectively.

[0133] See Figure 5 As shown, the carbon material obtained in Example 1 possesses both high order and a moderate number of defect sites, classifying it as a defect-type graphitic carbon with superior structure. The G peak is the most prominent and sharpest, the D peak is clear, and there is also a identifiable response in the 2D region, indicating that this sample maintains a certain number of defect sites while exhibiting good sp... 2 Orderliness of the carbon framework. Explanation: The composite catalyst system of Bi-Co-Cu alloy + modified CeO2, combined with modifications such as C3N4 / MoS2, sepiolite, and lithium oxalate, is indeed more conducive to the controlled nucleation and orderly growth of carbon.

[0134] Example 2 was able to generate graphitization-prone carbon materials at a low temperature of 600°C, but the carbon skeleton reconstruction was insufficient and the degree of graphitization was lower than that of Example 1.

[0135] The G peak in Example 3 is very strong and sharp, indicating that the carbon framework rearrangement is more complete under high temperature conditions. However, the D peak and its nearby shoulder / hybrid peaks are also quite obvious, indicating that although graphitization is enhanced, the structure is not completely homogeneous, and there are still many defects or edge sites caused by rapid local growth. This shows that high temperature promotes carbon deposition and graphitization, but also accelerates the thickening of the carbon layer and the non-homogenization of the structure.

[0136] Example 4 also has double peaks of D and G, and the resulting carbon material still has a certain graphitization structure. However, overall, the peak shape is weaker and wider than that of Example 1, and the 2D features are not prominent enough, indicating that the degree of order of the carbon material is lower than that of Example 1.

[0137] See Figure 6 As shown, Comparative Example 1 still exhibits a relatively obvious double peak of D and G, indicating that CeO2 itself is not completely ineffective and can still generate sp2-containing compounds.2 Structured carbon. However, the peaks in its spectrum are broader and the 2D response is weaker, indicating that the degree of carbon order is lower than that in Example 1.

[0138] The D / G doublet of Comparative Example 2 still exists, but the overall peak shape is blunter and broader, indicating that although the alloy catalyst can induce carbon precipitation, it has insufficient fine control over the carbon structure, and it is difficult to balance high-activity cracking and ordered carbon growth when using the alloy catalyst alone.

[0139] Comparative Example 3 has only the modified oxide and no molten alloy medium. Although the D / G doublet can also be seen in its Raman spectrum, the overall spectrum is broader and more heterogeneous, indicating insufficient ability for ordered growth of the carbon structure.

[0140] The D and G peaks of Comparative Example 4 are both sharp, and the 2D region is also relatively obvious. From the local spectral shape, there seems to be a certain area of highly ordered graphitic carbon, but due to insufficient composite interfaces, the overall uniformity and continuity of carbon growth are poor.

[0141] The D / G peak of Comparative Example 5 still exists, but the overall peak is broader, indicating that carbon can still be generated during the natural rise of bubbles without rotational dispersion, but the structural uniformity and degree of order decrease. This shows that the mass transfer / heat transfer conditions not only affect the cracking rate but also the uniformity of carbon growth.

[0142] In Comparative Example 6, the D and G peaks are broad and weak, and the 2D peak is very unobvious, indicating that the obtained carbon is more inclined to amorphous / low-order carbon, and the introduction of large bubbles leads to insufficient mass transfer and out-of-control local carbon deposition.

[0143] The D / G doublet still exists in Comparative Example 7, indicating that a certain amount of graphitic carbon can still be obtained initially or locally; however, the 2D is not prominent enough, indicating that its structural controllability and continuous stability are not as good as those in Example 1.

[0144] And, as shown in Figure 1 This application provides a system supporting this process. Combining with the process, it can be seen that the system has a high integration degree and is suitable for distributed and modular application scenarios. The whole process from methanol gasification, cracking reaction, gas separation to carbon collection is integrated, with a compact structure and flexible control, suitable for application scenarios such as distributed hydrogen production, mobile hydrogen sources, and coupling with methanol fuel cells, and has good engineering amplification potential and market adaptability.

[0145] As shown in Figure 1 Heat is collected on the reaction device 4 by the arch-shaped solar panel 7 to provide energy for the reaction. The heating device 2 is connected to a PSA pressure swing adsorption device, and the reaction mixture gas is separated through this device. As shown in Figure 1As shown, the separated hydrogen is collected and stored, while the small amount of oxygen byproduct produced is directly discharged to prevent it from reacting with the products in the subsequent reaction device 4. The unreacted methanol is reintroduced into the heating device 2, and then into the molten catalyst system of the reaction device 4 for catalytic cracking (in the direction of arrow ①). Byproduct gases such as carbon monoxide and carbon dioxide are introduced into the CO2 reactor. x Processing devices reduce carbon emissions.

[0146] During this process, some solid carbon will be generated in the reaction device 4. Due to its light weight, the solid carbon will rise with the gas to the surface of the molten catalyst system. The carbon floating on the surface of the molten catalyst system will accumulate continuously as the reaction continues. When the carbon accumulates to the height of the outlet 41, the carbon product is swept into the carbon storage bin through the outlet 41 by the rotating blade 42 for collection, and then carbon material is obtained, so that the reaction can continue for a long time.

[0147] Specifically, the catalyst system is housed in reaction apparatus 4, see [reference]. Figure 1 As shown, the heat-insulating pipe 3 is connected to the conduit 5. Methanol gas is passed through the conduit 5 to the bottom of the molten catalyst system, so that the methanol gas is in full contact with the catalyst system. Along the direction of methanol gas delivery, the aeration plate 6 set at the end of the conduit 5 rotates (at a speed of 300 r / min). The aeration plate 6 discharges the methanol gas in the form of bubbles and rises in the liquid molten metal. During the rising process, it undergoes a cracking reaction with the liquid molten catalyst system.

[0148] See Figure 1 As shown, the heating device 2 is equipped with two sensors 21. When the methanol level exceeds the upper sensor 21, the pump stops supplying methanol to the heating device 2. When the methanol level is lower than the lower sensor 21, the pump starts supplying methanol to the heating device 2.

[0149] See further Figure 1 As shown, a high-temperature resistant (>150℃) elastic gas collection bag 31 and a flow meter 32 are installed on the insulated pipe 3 to control the flow rate of methanol gas entering the reaction device 4. Along the conveying direction of the insulated pipe 3, a pressure detection device is installed at the front end and the rear end of the flow meter 32. The front end of the flow meter 32 is the first pressure detection device 33, and the rear end of the flow meter 32 is the second pressure detection device 34. When the reaction device 4 is blocked, the second pressure detection device 34 detects that the pressure is too high, and then controls the flow meter 32 to close and stop heating. When the methanol evaporates too quickly and the internal pressure exceeds the capacity of the elastic gas collection bag 31, the first pressure detection device 33 detects that the internal pressure of the pipe is too high, and then controls the pump to stop supplying methanol to the heating device 2 and stops heating the heating device 2 to reduce methanol evaporation. It also opens the channel to release the internal pressure and collect the vaporized methanol again.

[0150] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A process for methanol cracking to produce hydrogen and carbon, characterized in that, It includes the following steps: a. Preparation of methanol gas: Methanol liquid is continuously heated to 68~75℃ to vaporize the methanol liquid and obtain methanol gas; b. Methanol cracking via a catalyst system: Under an argon atmosphere, the catalyst system is heated to a predetermined temperature, and methanol gas is introduced to carry out methanol cracking to produce hydrogen and carbon. The catalyst system includes an alloy catalyst and a modified metal oxide catalyst, wherein the mass ratio of the alloy catalyst to the modified metal oxide catalyst is (4~4.5):1, and the predetermined temperature is 600~1000℃. c. Product collection: Collect the hydrogen and carbon materials obtained from the pyrolysis; The preparation method of the alloy catalyst includes the following steps: S101. After cleaning and activating the metal particles, dry them; The metal particles comprise a primary metal and a secondary metal, wherein the primary metal is selected from Bi, and the secondary metal is selected from at least one of Co, Mn, Cu, Fe, and Ni. The molar ratio of the secondary metal to the primary metal is (3~4):6; S102. Under an argon protective atmosphere, the secondary metal is heated to 1400~1600℃ by electric arc to melt and obtain an alloy ingot. After cooling, it is placed in a furnace together with Bi, argon is added again, and it is heated to 780~800℃ for melting. Modifier is added so that Bi and the alloy ingot are co-melted. After annealing, an alloy catalyst is obtained. The modifier is selected from lithium oxalate or yttrium carbonate, and the amount of the modifier added is 4-6% of the mass of Bi. The preparation method of the modified metal oxide catalyst includes the following steps: S201. Disperse the metal oxide in deionized water, sonicate it, add hydroxyethyl cellulose, stir, filter and dry, and calcine at 420~450℃ for 1~2h to obtain a pretreated carrier; the amount of hydroxyethyl cellulose added is 1~2% of the mass of the metal oxide; the metal oxide is selected from CeO2, La2O3, ZnO or CuO. S202. The pretreated carrier is immersed in a suspension modification liquid, stirred and allowed to stand at room temperature for 10-12 hours, dried and then calcined at 600-700℃ for 2-3 hours under an argon atmosphere to obtain the modified carrier. The preparation method of the suspension modified liquid is as follows: carbon nitride and molybdenum disulfide are mixed at a mass ratio of (2~3):1, anhydrous ethanol is added, and ultrasonic dispersion is carried out for 40~60 min to obtain the suspension modified liquid; S203. The modified support is mixed and ground with sepiolite, 5 wt% microcrystalline cellulose suspension is added, stirred and filtered; then the filtered product is impregnated in 0.5 mol / L lithium oxalate solution, stirred for 2-3 h, filtered and dried, calcined at 500-600℃ for 1.5-2 h, and cooled to obtain the modified metal oxide catalyst. The amount of sepiolite added is 4-5% of the mass of the modified carrier, and the amount of microcrystalline cellulose suspension added is 40-50% of the mass of the modified carrier.

2. The methanol cracking process for hydrogen and carbon production as described in claim 1, characterized in that: S101 includes the following steps: Using carbon cloth as the substrate for metal particles, the metal particles were ultrasonically cleaned sequentially with acetone and ethanol. The cleaned metal particles were then activated by immersion in dilute hydrochloric acid solution, rinsed with deionized water, and dried at 110~120℃.

3. The methanol cracking process for hydrogen and carbon production as described in claim 1, characterized in that: In step S102, the annealing operation includes the following steps: The alloy obtained by co-melting Bi with alloy ingots is sealed in a vacuum-sealed quartz ampoule and annealed at 280~300℃ for 8~10h to obtain an alloy catalyst.

4. A methanol cracking hydrogen and carbon production system, based on the methanol cracking hydrogen and carbon production process according to any one of claims 1 to 3, characterized in that, The system includes: Storage tank and heating device; The reaction apparatus includes a heating device connected to the reaction apparatus via an insulated pipe, a dispersion component at the bottom of the reaction apparatus, and an outlet on the side wall of the reaction apparatus. A pressure swing adsorption device, which is connected to the reaction device.

5. The methanol cracking hydrogen-to-carbon production system as described in claim 4, characterized in that: The dispersion component includes a conduit and an aeration plate. The conduit is connected to an insulated pipe and runs along the direction of methanol gas transport. The aeration plate is located at the end of the conduit and at the bottom of the reaction device. The aeration plate discharges methanol gas in the form of bubbles and rises to react with the catalyst system in a cracking reaction. The rotational speed of the aeration disc is 100~500 r / min.

6. The methanol cracking hydrogen-to-carbon production system as described in claim 4, characterized in that: The reaction device is equipped with rotating blades, which are flush with the outlet.

7. The methanol cracking hydrogen and carbon production system as described in claim 4, characterized in that: The heating device is equipped with a sensor. The insulated pipe is equipped with an elastic gas collection bag and a flow meter; along the conveying direction of the insulated pipe, a pressure detection device is installed at the front end and the rear end of the flow meter.

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