Method for producing hydrogen by electrolyzing methanol by using Pd-Ru nanoparticle nitrogen-doped carbon catalyst with temperature dynamically controlled by thermocouple

Abstract

The invention discloses a method for producing hydrogen by electrolyzing methanol by using a Pd-Ru nanoparticle nitrogen-doped carbon catalyst with temperature dynamically controlled by a thermocouple in the technical field of electrochemical energy. The method comprises the following steps: constructing a reaction system by using a transparent polycarbonate electrolytic bath and an anion exchange membrane; a specific catalyst and a binder are rolled to prepare a microporous electrode, and the microporous electrode is compounded with a metal current collector to prepare a working electrode. The system integrates various thermocouples to monitor the temperature of a catalyst layer and the electrolyte in real time, and adopts a fuzzy logic algorithm to dynamically adjust a temperature control mechanism, so that the temperature of an electrode interface microcell is accurately and stably controlled. The catalyst is prepared by taking waste crab shells as raw materials, performing high-temperature carbonization and nitrogen doping treatment to obtain a carrier, performing microwave synthesis and laser processing to form a palladium ruthenium heterojunction nanocluster, and finally performing anion exchange resin bonding and electrochemical activation. The catalytic efficiency and the hydrogen production rate of methanol electrolysis hydrogen production can be effectively improved, and long-time continuous and stable operation of the system is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste resource utilization, and particularly relates to a method for electrolyzing methanol to produce hydrogen by using a Pd-Ru nanoparticle nitrogen-doped carbon catalyst with dynamic temperature control of a thermocouple. BACKGROUND

[0002] Hydrogen energy, as a clean and efficient secondary energy, has become an important direction of global energy transformation. Although the traditional water electrolysis hydrogen production technology is relatively mature, it has the bottleneck problems of high energy consumption and low efficiency, which is difficult to meet the demand of large-scale commercial application. In recent years, the mixed electrolysis hydrogen production technology using organic matter electrolysis oxidation reaction instead of oxygen evolution reaction coupled with hydrogen evolution shows the application potential of significantly reducing energy consumption. Among them, methanol is considered as an ideal liquid carrier due to its convenient storage and transportation and low theoretical electrolysis voltage, and the methanol electrolysis hydrogen production technology has thus become a research hotspot. The core of the technology is the design and preparation of the anode methanol oxidation reaction catalyst and the optimization and regulation of the reaction process, aiming to improve the reaction kinetics rate and energy conversion efficiency.

[0003] However, the existing methanol electrolysis hydrogen production technology still faces several key technical challenges. First, the comprehensive performance of the catalyst needs to be improved. Although the noble metal platinum-based catalyst has excellent activity, it is high in cost and poor in anti-poisoning ability, and is easily poisoned and deactivated by the intermediate products of methanol oxidation. Non-noble metal catalysts are usually difficult to meet the actual application requirements in terms of intrinsic activity and stability. Developing a new catalyst system with high activity, high stability and cost-effectiveness is the key to promoting the development of the technology. Second, the heat management problem in the reaction process is prominent. Methanol oxidation reaction is strongly dependent on temperature, and local micro-zone temperature fluctuation will significantly affect the reaction rate, product selectivity and catalyst durability. The existing system mostly uses macroscopic tank temperature monitoring and regulation, which is difficult to realize precise perception and dynamic management of the micro-zone temperature at the electrode-electrolyte interface, resulting in unstable reaction process and energy loss. In addition, the problems of concentration polarization and catalyst deactivation generated during long-time operation also restrict the continuous stable operation time and hydrogen production efficiency of the system.

[0004] In view of the above technical bottlenecks, it is urgent to develop a new methanol electrolysis hydrogen production method integrating advanced catalyst design and precise process regulation. The ideal solution should be able to construct low-cost and high-performance catalytic materials through innovative catalyst preparation process; at the same time, a real-time and accurate micro-zone temperature sensing and dynamic control system needs to be established to ensure the best and stable thermal environment at the reaction interface; in addition, effective online purification and regeneration strategies need to be matched to inhibit side reactions and maintain the stability of long-term operation of the system. Through the collaborative innovation of multiple technical paths, the efficient, stable and controllable methanol electrolysis hydrogen production process is finally realized, which provides strong technical support for the economic and feasible preparation of green hydrogen energy. SUMMARY

[0005] The application aims to provide a Pd-Ru nanoparticle nitrogen-doped carbon catalyst electrolysis methanol hydrogen production method with thermocouple dynamic temperature control, which solves the technical problems of insufficient catalyst activity, inaccurate temperature control and long-term stable operation of the system in the existing methanol electrolysis hydrogen production process.

[0006] The application achieves the above-mentioned purpose through the following technical solutions: The Pd-Ru nanoparticle nitrogen-doped carbon catalyst electrolysis methanol hydrogen production method with thermocouple dynamic temperature control comprises the following steps: S1, a transparent polycarbonate is used to process an electrolytic cell with a three-dimensional flow channel structure, and an anode chamber and a cathode chamber are separated by an anion exchange membrane; a Pd-Ru nanoparticle nitrogen-doped carbon catalyst is uniformly mixed with a polytetrafluoroethylene emulsion and then roll-pressed to form a catalytic electrode sheet with a microporous structure, the catalytic electrode sheet is hot-pressed with a titanium metal foam current collector to form a working electrode, a counter electrode is a stainless steel mesh loaded with Pt / C, and a reference electrode is a mercury / mercury oxide electrode; S2, two types of thermocouples are respectively integrated and installed in the anode chamber: a K-type armored thermocouple is directly embedded in the working electrode to monitor the temperature of the catalyst layer in real time; meanwhile, three micro thin film thermocouples are arranged in the electrolyte flow channel parallel to the electrode surface, and all thermocouple signals are transmitted to the control system through a high-precision data acquisition card; S3, based on the collected temperature data, a fuzzy logic algorithm is used to calculate the temperature deviation and the deviation change rate in real time, and the proportion, integral and differential parameters of the PID controller are dynamically adjusted; output control signals drive the following actuators: a semiconductor refrigeration sheet, a micro piezoelectric ceramic pump, and a pulse width modulation controlled infrared heating lamp array; S4, the electrolyte is a mixed solution of methanol and potassium hydroxide, which is activated by three cycles of cyclic voltammetry, and then the electrolysis system is started under a constant current density of 500-510 mA / cm²; the temperature control system stably controls the micro zone temperature at the electrode / electrolyte interface to be 64.5-65.5℃, and every 30-40min is switched to an open circuit potential state by a pulse method to eliminate concentration polarization; the hydrogen production purity is analyzed online by gas chromatography, the hydrogen production rate is measured by the drainage method, and the system is continuously operated.

[0007] In the present application, the thermocouple dynamic temperature control methanol electrolysis hydrogen production method is based on the synergistic coupling of anode methanol oxidation and cathode hydrogen evolution reaction. In the alkaline electrolysis environment, methanol molecules undergo a complex multi-electron transfer process on the surface of the anode catalyst, ultimately generating carbonate ions and releasing electrons; at the same time, water molecules accept electrons at the cathode to produce hydrogen. The reaction efficiency of the whole process is highly dependent on the intrinsic activity of the catalyst active site, mass transfer efficiency and temperature distribution of the reaction interface. The anode methanol oxidation reaction follows the hydroxyl assisted mechanism. On the surface of the palladium ruthenium nanoparticle nitrogen-doped carbon catalyst, the hydroxyl ions provided by the potassium hydroxide electrolyte first adsorb on the catalyst active site to form a hydroxyl species. The methanol molecules then interact with these hydroxyl species, undergo a multi-step dehydrogenation process to gradually generate formic acid intermediates, and are finally oxidized to carbonate ions. In this reaction path, the palladium element mainly provides the active sites for methanol adsorption and initial C-H bond breaking, while the ruthenium element promotes the adsorption and activation of the hydroxyl species, both of which synergistically reduce the reaction energy barrier. The nitrogen-doped carbon carrier not only provides a high specific surface area and a conductive network, but also adjusts the electronic structure of the metal nanoparticles through the doped nitrogen atoms, enhances the metal-support interaction, and further improves the stability and poisoning resistance of the catalyst. It is worth noting that intermediate products such as carbon monoxide produced during the reaction can poison the catalyst active sites, but by precisely controlling the reaction interface temperature within the optimal range, the further oxidation of intermediate products can be accelerated, effectively alleviating catalyst poisoning. The cathode hydrogen evolution reaction is relatively simple, with water molecules being reduced to produce hydrogen at the cathode. Due to the theoretical potential of the anode methanol oxidation reaction being much lower than that of the water oxidation reaction, the cell voltage of the entire electrolysis process is significantly reduced, thereby achieving low-energy hydrogen production. During the reaction, the anion exchange membrane allows hydroxyl ions to migrate from the cathode to the anode, maintaining the charge balance of the entire system. The design of the three-dimensional flow channel optimizes the flow state of the electrolyte, ensuring efficient mass transfer of reactants and products. In particular, the multi-point thermocouple monitoring and dynamic temperature control system used in the present application plays a crucial role in the implementation of the reaction mechanism. By monitoring the temperature distribution of the catalyst layer and the electrolyte flow channel in real time, and using intelligent algorithms to dynamically adjust the cooling and heating devices, the high stability of the reaction interface temperature is ensured. This precise temperature control not only optimizes the reaction kinetics, but also avoids catalyst sintering and deactivation caused by local overheating, as well as changes in the reaction path caused by temperature fluctuations, thereby ensuring reaction selectivity and long-term stability. The introduction of periodic open circuit potential further eliminates concentration polarization, allowing the catalyst surface active sites to be temporarily restored and maintaining the high efficiency of the reaction.

[0008] According to the preferred embodiment of the present application, in step S1, the thickness of the catalytic electrode sheet is 0.5-0.52mm.

[0009] According to the preferred embodiment of the present application, in step S2, the diameter of the K-type armored thermocouple is 0.1-0.12mm.

[0010] According to the preferred embodiment of the present application, in step S3, the semiconductor refrigeration sheet acts on the outer wall of the electrolytic cell for bulk temperature regulation, the micro piezoelectric ceramic pump controls the pulse injection of pre-cooled methanol solution for local micro-zone cooling, and the pulse width modulation controlled infrared heating lamp array performs compensatory heating on the edge area of the electrode.

[0011] In step S3 of the present application, the temperature dynamic control process is an intelligent closed-loop control system based on multi-sensor information fusion, the core of which is to convert macro temperature measurement into precise micro local temperature regulation through advanced algorithms. The system first establishes a temperature monitoring network by arranging two kinds of thermocouples at different spatial positions to comprehensively capture the thermal dynamic process. Among them, the extremely thin armored thermocouple is directly embedded in the working electrode to contact the catalyst layer, directly monitoring the real temperature of the reaction exothermic core area, and the temperature change at this point is the most direct and rapid indication of the reaction load of the system; at the same time, three micro thin film thermocouples are arranged in the electrolyte flow channel parallel to the electrode surface to form a temperature sensor array, which reflects the heat and mass transfer state by monitoring the temperature gradient change along the flow direction, and the electrolyte temperature distribution directly reflects the efficiency of the reaction heat being carried away and the uniformity of the flow field, and an abnormal temperature rise at a certain point may indicate that the flow channel is blocked or the liquid flow is stagnant. The weak millivolt-level analog signals generated by all thermocouples are collected in real time by a high-precision data acquisition card and converted into digital signals, and the high resolution and high sampling rate ensure that the subtle fluctuations of temperature changes can be captured, laying a data foundation for subsequent high-precision control. In the intelligent decision-making stage, the system combines fuzzy logic algorithm with traditional PID controller to achieve superior dynamic response and robustness. The system first calculates the temperature deviation, i.e. the difference between the set target temperature and the actual temperature of the catalyst layer, and the temperature deviation rate, i.e. the change speed of the deviation; then the precise input value is converted into a fuzzy language variable according to the pre-set membership function through fuzzy processing; the system has a rule base based on expert experience to define how to adjust the PID parameters for different deviation combinations, and the relevant rules are activated and weighted calculated according to the current fuzzy input, and finally the instruction of precise adjustment of PID parameters is output; the proportional, integral and differential parameters of the PID controller are adjusted in real time online according to the fuzzy reasoning output: the proportional coefficient mainly affects the response speed, which is increased when the deviation is large to quickly approach the target, and is reduced when the deviation is small to avoid oscillation; the integral coefficient is used to eliminate static error, which is increased when the system is stable to accelerate the elimination of small deviations, and is reduced when the system fluctuates sharply to prevent integral saturation and overshoot; the differential coefficient predicts the trend and suppresses the overshoot, and is increased when a sharp temperature change is detected to produce a reverse suppression effect to stabilize the process. The final control signal drives three different actuators to achieve precise and stable control of the interface micro-zone temperature from the macro, micro and compensation levels. The semiconductor refrigeration piece acts on the outer wall of the electrolytic cell to adjust the macro main body temperature, which receives the main control signal output by the controller to respond to environmental temperature changes and the basic heat load caused by continuous reaction heat production, and drives the refrigeration piece to actively dissipate heat when the overall system temperature is too high, and reversely works to heat when the temperature is too low to maintain the thermal balance of the whole system.The micro piezoelectric ceramic pump is responsible for local micro area cooling, receives high frequency or mutation components in the output of the controller, and drives a pulse width modulation signal when detecting instantaneous temperature rise or local hot spots of the catalyst layer, so that the piezoelectric pump can pulse inject pre-cooled methanol solution to the overheated area with extremely high precision, directly and quickly eliminate local overheating through the instantaneous evaporation of cold liquid drops, and the response speed is much faster than that of traditional cooling methods, which is specially used to deal with instantaneous severe heat fluctuations caused by uneven reaction or bubble accumulation. The pulse width modulation controlled infrared heating lamp array is responsible for edge compensation heating. Based on the temperature gradient data of the flow channel thermocouple array, when detecting that the temperature of the electrode edge or flow channel outlet and other areas is low, the driving signal controls the infrared lamp array to perform directional compensatory radiation heating on these specific areas, so as to eliminate the temperature unevenness in the electrolytic cell and ensure that the entire electrode surface reaction is carried out within the optimal temperature range, avoiding the decline of the overall efficiency caused by the edge effect. The three-in-one execution mode realizes high-precision and high-stability dynamic control of the micro area temperature of the methanol electrolysis hydrogen production reaction interface, and is the key technology to ensure the high-efficiency and stable long-time operation of the method.

[0012] According to the preferred embodiment of the present application, in step S4, the switching time to the open circuit potential state by pulse method is 10-12s, and the continuous operation time is 24-30h.

[0013] According to the preferred embodiment of the present application, the preparation steps of the Pd-Ru nanoparticle nitrogen-doped carbon catalyst include: A1, after repeatedly washing the waste crab shell with deionized water, crushing and sieving, placing it in a tube furnace and carbonizing it under nitrogen atmosphere to obtain a primary carbonized product; mixing and grinding the primary carbonized product with melamine, adding zinc chloride, and heating to 900-905 DEG C under argon protection, then naturally cooling, soaking in HCl solution, and drying after dialysis to obtain a nitrogen-doped carbon carrier; A2, dispersing the nitrogen-doped carbon carrier in an ethylene glycol solution and ultrasonic treatment, weighing tetrachloropalladic acid and ruthenium trichloride hydrate, adding sodium citrate, and irradiating in a microwave reactor at 178-182 DEG C, then collecting by centrifugation and vacuum drying to obtain a precursor composite material; A3, pressing the precursor composite material into a sheet and placing it in a reaction chamber, introducing high-purity argon, and using a Nd:YAG laser to scan the surface of the material to obtain Pd-Ru heterojunction nanoclusters; A4, mixing the Pd-Ru heterojunction nanoclusters after laser treatment with a polyarylether sulfone quaternary ammonium salt solution, uniformly coating it on a carbon paper electrode, placing it in a potassium hydroxide solution for cyclic voltammetry activation treatment, and finally washing with ultrapure water and drying at 60-64 DEG C under argon atmosphere.

[0014] In the present application, the preparation process of the palladium-ruthenium nanoparticle nitrogen-doped carbon catalyst involves multiple key steps, and the reaction mechanism covers multiple aspects such as carbon carrier synthesis, metal loading and structure regulation. The preparation process takes waste crab shells as raw materials, constructs a porous carbon carrier through high-temperature carbonization and nitrogen-doping treatment, then constructs palladium-ruthenium heterojunction nanoclusters through microwave-assisted synthesis and laser treatment, and finally optimizes the surface state of the catalyst through electrochemical activation. Crab shells, as a natural biological template, are composed of chitin and calcium carbonate. After high-temperature carbonization treatment, a carbon material with hierarchical porous structure is formed. In a nitrogen atmosphere, part of the nitrogen-containing groups in chitin are preserved and doped into the carbon skeleton to form a nitrogen-doped carbon matrix. Then mixed with melamine and treated at high temperature, the nitrogen-doping content is further improved and a rich pore structure is created. The addition of zinc chloride as an activator creates a large number of micropores and mesopores through activation at high temperature, significantly increasing the specific surface area. Hydrochloric acid treatment removes the calcium carbonate template and residual zinc species, forming a carbon carrier with rich nitrogen species and pore structure. These nitrogen species include pyridine nitrogen, pyrrole nitrogen and graphite nitrogen in various forms, which not only provide metal anchoring sites, but also adjust the electronic properties of the carbon carrier, enhancing the interaction with metal nanoparticles. During the metal loading stage, there is strong coordination between the nitrogen atoms on the surface of the nitrogen-doped carbon carrier and the palladium and ruthenium metal precursors, which fixes the metal ions on the surface of the carrier through electrostatic adsorption and coordination bonding. Microwave radiation treatment provides a uniform and rapid heating environment, prompting the ethylene glycol reducing agent to reduce the metal ions to metal nanoparticles. Sodium citrate acts as a stabilizer, controlling the growth of nanoparticles and preventing agglomeration through carboxyl coordination with the metal surface. The most critical laser treatment step involves the use of a high-energy density laser beam to instantaneously act on the material surface, creating a local high-temperature and high-pressure environment that allows palladium and ruthenium atoms to rearrange and form a heterojunction structure. During laser treatment, the metal nanoparticle surface melts and recrystallizes, forming palladium-ruthenium heterojunction nanoclusters with rich interface effects. This heterostructure promotes electron transfer between palladium and ruthenium, optimizes the d-band center position, and enhances the adsorption-desorption behavior of reaction intermediates. The final electrochemical activation process is carried out in potassium hydroxide solution, which further optimizes the catalyst surface electronic structure through multiple redox cycles, removes surface unstable species, exposes more high-activity crystal faces, and forms an electron-rich metal-carrier interface. Ultimately, a palladium-ruthenium nanoparticle nitrogen-doped carbon catalyst with high activity and stability is obtained.

[0015] According to the preferred embodiment of the present application, in step A1, the carbonization time is 2-4 h at 600-604℃; the temperature is raised to 900-905℃ and the holding time is 1-2 h.

[0016] According to the preferred embodiment of the present application, in step A2, the ultrasonic treatment time is 2-4 h; the radiation treatment time is 15-20 min at 178-182℃.

[0017] According to the preferred embodiment of the present application, in step A3, the scanning rate is 2-4 mm / s.

[0018] According to the preferred embodiment of the present application, in step A4, the drying time at 60-64℃ is 12-14 h.

[0019] The present application has the following beneficial effects: The thermocouple dynamic temperature control methanol electrolysis hydrogen production method provided by the present application has significant technical effects, mainly in three aspects of catalyst performance, temperature control accuracy and system running stability. First, the palladium-ruthenium nanoparticle nitrogen-doped carbon catalyst used in the present application exhibits excellent electrocatalytic performance. The nitrogen-doped carbon carrier prepared from waste crab shells has abundant pore structure and good electrical conductivity, providing an ideal loading platform for metal nanoparticles. The palladium-ruthenium heterojunction nanoclusters formed by microwave synthesis and laser processing effectively regulate the electronic structure and enhance the intrinsic activity of the catalytic active center. The catalyst exhibits high activity and selectivity for methanol oxidation reaction in alkaline environment, significantly reduces the anode reaction overpotential, and improves the energy conversion efficiency of the overall reaction. At the same time, the catalyst has good resistance to poisoning and durability, can effectively resist the poisoning effect of reaction intermediates, and maintains long-term stable catalytic performance.

[0020] Secondly, the innovative multi-stage thermocouple dynamic temperature control system realizes precise regulation of the reaction micro-zone temperature. By embedding armored thermocouples in the working electrode and arranging micro thin film thermocouples in the electrolyte flow channel, a three-dimensional temperature monitoring network is constructed, which can capture the temperature changes of the catalyst layer and the liquid-solid interface in real time. The fuzzy logic algorithm is used to dynamically adjust the control parameters, and through the synergistic effect of semiconductor refrigeration pieces, micro piezoelectric pumps and infrared heating lamp arrays, the multi-level accurate control of the main temperature of the electrolytic cell, the local micro-zone temperature and the electrode edge temperature is realized. This advanced temperature control strategy controls the temperature fluctuation of the electrode-electrolyte interface micro-zone within a very narrow range, creating the best and stable thermal environment for methanol oxidation reaction, effectively improving the reaction kinetics rate and product selectivity.

[0021] Finally, the overall system exhibits excellent running stability and hydrogen production performance. The unique three-dimensional flow channel structure design combined with the periodic open circuit potential elimination polarization strategy effectively avoids concentration polarization and catalyst deactivation, ensuring that the system can run continuously and stably for a long time. The anion exchange membrane system and alkaline electrolyte have good compatibility with the catalyst and the binder, ensuring the efficiency of ion conduction and the chemical stability of the system. Experimental results show that this method can achieve high hydrogen production rate and high purity hydrogen production, while significantly reducing energy consumption, providing a reliable technical solution for large-scale and economic production of green hydrogen energy. DETAILED DESCRIPTION

[0022] The following detailed description is provided for further understanding of the present application and should not be construed as limiting the scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0023] The main related equipment and material suppliers are as follows: The polycarbonate was purchased from Wanhua Chemical Group Co., Ltd.

[0024] The polytetrafluoroethylene emulsion was purchased from Shandong Dongyue High Polymer Material Co., Ltd.

[0025] The potassium hydroxide was purchased from Xinjiang Zhongtai Chemical Co., Ltd.

[0026] The tube furnace was purchased from Hefei Kecheng Material Technology Co., Ltd.

[0027] The melamine was purchased from Sichuan Jinxing Saier Chemical Co., Ltd.

[0028] The zinc chloride was purchased from Hunan Zhuye Group Co., Ltd.

[0029] The argon was purchased from Hangzhou Hangyang Co., Ltd.

[0030] The HCl solution was purchased from Jiangsu Qiangsheng Functional Chemical Co., Ltd.

[0031] The tetrachloropalladic acid was purchased from Guiyan Platinum Industry Co., Ltd.

[0032] The ruthenium trichloride hydrate was purchased from Xi'an Kailixin Material Co., Ltd.

[0033] The sodium citrate was purchased from Shandong Yingxuan Industry Co., Ltd.

[0034] The microwave reactor was purchased from Nanjing Laibu Technology Co., Ltd.

[0035] The Nd:YAG laser was purchased from Shenzhen Datuchui Laser Science and Technology Industry Group Co., Ltd.

[0036] The polyarylether sulfone quaternary ammonium salt was purchased from Wuhan Zhongke Kun Engineering Technology Co., Ltd.

[0037] Example 1 The method for electrolyzing methanol to produce hydrogen by using a thermocouple dynamic temperature control palladium-ruthenium nanoparticle nitrogen-doped carbon catalyst is as follows. First, the catalyst is prepared: 100.0 g of waste crab shell material that has been repeatedly cleaned with deionized water and crushed to 80 mesh is accurately weighed, evenly laid in an alumina crucible, and placed in the constant temperature zone of a tube furnace. Under the protection of high-purity nitrogen gas with a flow rate of 200 mL / min, the temperature is programmed to rise at a rate of 10 ℃ / min to 602 ℃, and the temperature is kept constant for 3.0 h of carbonization at this temperature. After natural cooling to room temperature, a black primary carbonization product is obtained. 30.0 g of the primary carbonization product is ground with 30.0 g of melamine in a agate mortar for 30 min, and then 10.0 g of zinc chloride is added and ground for another 20 min to mix them evenly. The mixture is transferred to a corundum boat, and under the protection of high-purity argon gas with a flow rate of 150 mL / min, the temperature is programmed to rise at a rate of 5 ℃ / min to 903 ℃, and the mixture is activated at this temperature for 1.5 h. After the reaction is completed, the mixture is naturally cooled to room temperature, soaked in a 1.0 mol / L hydrochloric acid solution for 6.0 h, stirred every 1 h during the soaking, then dialyzed with deionized water for 72 h until the pH is neutral, and finally dried in a vacuum drying oven at 80 ℃ for 12 h to obtain a nitrogen-doped carbon carrier. 20.0 g of the nitrogen-doped carbon carrier is dispersed in 200 mL of ethylene glycol solution, and ultrasonic treatment is performed under the conditions of a power of 300 W and a frequency of 40 kHz for 3.0 h to form a uniform suspension. 0.5 g of palladium chloride and 0.3 g of ruthenium trichloride hydrate are accurately weighed, 1.0 g of sodium citrate is added as a stabilizer, the mixture is dissolved, and then added to the suspension. The mixed solution is transferred to a 100 mL microwave reaction kettle, placed in a microwave reactor, and irradiated at 180 ℃ for 18 min, with the reaction pressure maintained at 2.0 MPa. After the reaction is completed, the solid product is collected by centrifugation, washed with anhydrous ethanol and deionized water three times each, and dried in a vacuum drying oven at 60 ℃ for 12 h to obtain a precursor composite material. The precursor composite material is pressed into a sheet-shaped material with a thickness of 2 mm under a pressure of 10 MPa, and placed in a transparent quartz reaction chamber. High-purity argon gas with a flow rate of 100 mL / min is introduced as a protective gas, a Nd:YAG laser with a wavelength of 1064 nm is used, the scanning speed is 3 mm / s, the power is 50 W, the spot diameter is 100 μm, the scanning interval is 50 μm, and the material surface is scanned three times to obtain palladium-ruthenium heterojunction nanoclusters. 0.1 g of the laser-treated nanoclusters is accurately weighed, mixed with 1.0 g of polyaryl ether sulfone quaternary ammonium salt solution (solid content 10%), 5 mL of N,N-dimethylformamide is added as a solvent, and ultrasonic dispersion is performed for 30 min to form a uniform slurry. The slurry is uniformly coated on a 2 cm×2 cm carbon paper electrode by using a doctor blade method, and the catalyst loading is 1.0 mg / cm².The modified electrode was placed in 1.0 mol / L potassium hydroxide solution, and 10 cycles of cyclic voltammetry activation treatment were performed at a scan rate of 50 mV / s in the potential range of -0.2 to 0.8 V (vs. Hg / HgO) by using an electrochemical workstation. Finally, the electrode surface was rinsed with ultrapure water and dried in a vacuum drying oven at 62°C under argon atmosphere protection for 13 h to obtain the final working electrode.

[0038] Electrolysis process: A transparent polycarbonate electrolysis cell with a size of 10 cm x 10 cm x 2 cm was processed by using a numerical control machine tool. The flow channel depth was 1 mm, and the width was 2 mm. A serpentine flow channel design was used. The anode chamber and the cathode chamber were separated by a cation exchange membrane with a thickness of 50 μm. The prepared catalytic electrode sheet and 2 mm thick titanium metal foam current collector were combined by hot pressing to form a working electrode. The hot pressing conditions were 120°C, 5 MPa pressure for 5 min. The counter electrode was a stainless steel mesh loaded with 0.1 g of Pt / C catalyst (platinum loading 20%). The reference electrode was a mercury / mercury oxide electrode (filled with 1.0 mol / L potassium hydroxide solution). Two types of thermocouples were integrated and installed inside the anode chamber: a K-type armored thermocouple with a diameter of 0.11 mm was directly embedded inside the working electrode, and the thermocouple temperature measuring end was 0.1 mm away from the surface of the catalyst layer. At the same time, three micro thin film thermocouples were arranged at equal intervals in the electrolyte flow channel 1 mm away from the electrode surface. All thermocouple signals were transmitted in real time to the control system at a sampling frequency of 10 Hz by using a 24-bit high-precision data acquisition card. Based on the collected temperature data, a fuzzy logic algorithm was used to calculate the temperature deviation and deviation rate in real time, and dynamically adjust the proportional, integral and derivative parameters of the PID controller. The output control signals drive the following actuators: a semiconductor refrigeration piece (maximum refrigeration power 200 W) acts on the outer wall of the electrolysis cell for main temperature regulation; a micro piezoelectric ceramic pump controls the pulse injection of methanol solution pre-cooled to 20°C for local micro-zone cooling; a pulse width modulated control infrared heating lamp array performs compensation heating on the edge area of the electrode. The electrolyte used was a 200 mL methanol and 1.0 mol / L potassium hydroxide mixed solution, with a methanol concentration of 2.0 mol / L. After 3 cycles of cyclic voltammetry activation at a scan rate of 50 mV / s in the working potential range, the electrolysis system was started at a constant current density of 505 mA / cm². The temperature control system stably controlled the micro-zone temperature at the electrode / electrolyte interface to 65.0°C, with a control accuracy of ±0.1°C. Every 35 min, the pulse method was used to switch to the open circuit potential state for 12 s to eliminate concentration polarization. The hydrogen production rate was measured by the drainage gas collection method, and the hydrogen purity was analyzed by online gas chromatography (TCD detector, 13X molecular sieve column). The system was continuously and stably operated for 28 h.

[0039] Example 2 The specific embodiment is the same as that of Example 1, except that the method for electrolyzing methanol to produce hydrogen by using the palladium-ruthenium nanoparticle nitrogen-doped carbon catalyst dynamically controlled by thermocouples comprises the following steps. First, the catalyst is prepared: 120 g of discarded crab shells are cleaned, crushed, and placed in a tube furnace, and carbonized at 10 ℃ / min to 600 ℃ under a nitrogen atmosphere for 2 h to obtain a primary carbonization product. The product is mixed with 25 g of melamine and ground, 8 g of zinc chloride is added, and the mixture is heated to 901 ℃ at 5 ℃ / min under an argon atmosphere and kept for 1.2 h, and then naturally cooled and soaked in 1 mol / L HCl solution for 6 h, and then dried by dialysis to obtain a nitrogen-doped carbon carrier. 18 g of the nitrogen-doped carbon carrier is dispersed in 200 mL of ethylene glycol solution and ultrasonically treated for 2.5 h, 0.4 g of tetrachloropalladium acid and 0.25 g of ruthenium trichloride hydrate are weighed, 0.8 g of sodium citrate is added, and the mixture is treated in a microwave reactor at 179 ℃ for 16 min, and then collected by centrifugation and dried at 60 ℃ under vacuum to obtain a precursor composite material. The material is pressed into a sheet and placed in a reaction chamber, high-purity argon is introduced, and a Nd:YAG laser is used to scan the surface of the material at a speed of 2.5 mm / s to obtain palladium-ruthenium heterojunction nanoclusters. 0.08 g of the nanoclusters after laser treatment is mixed with 0.8 g of a polyaryl ether sulfone quaternary ammonium salt solution, coated on a carbon paper electrode, placed in 1 mol / L potassium hydroxide solution, and subjected to cyclic voltammetry activation treatment for 10 cycles at a scan rate of 50 mV / s, and finally washed with ultrapure water and dried at 60 ℃ under an argon atmosphere for 12 h. The electrolysis process: a three-dimensional flow channel electrolysis cell is made of transparent polycarbonate, and the anode chamber and the cathode chamber are separated by an anion exchange membrane. 0.4 g of the prepared catalyst is mixed with 0.08 g of a polytetrafluoroethylene emulsion and roll-pressed into a 0.50 mm thick catalytic electrode sheet, which is hot-pressed with a titanium metal foam current collector to form a working electrode. The counter electrode is a stainless steel mesh loaded with 0.1 g of Pt / C catalyst, and the reference electrode is a mercury / mercuric oxide electrode. A K-type armored thermocouple with a diameter of 0.10 mm is embedded in the anode chamber to monitor the temperature of the catalyst layer, and three micro thin-film thermocouples are arranged in the electrolyte flow channel. All signals are transmitted to the control system through a data acquisition card, the fuzzy logic algorithm is used to calculate the temperature deviation and the rate of change of the deviation, the PID parameters are dynamically adjusted, the output signal drives the semiconductor refrigeration sheet to adjust the main temperature of the cell body, the micro piezoelectric ceramic pump pulses the pre-cooled methanol solution for micro cooling, and the pulse width modulation infrared heating lamp array compensates for heating at the edge of the electrode. The electrolyte is a mixture of 200 mL of methanol and 1 mol / L potassium hydroxide solution, which is first activated by cyclic voltammetry for 3 cycles, and then the system is started at a current density of 500 mA / cm². The temperature control system stably controls the interface micro zone temperature at 64.8 ℃, and every 30 min is switched to an open circuit potential state for 10 s to eliminate concentration polarization. The hydrogen production rate is measured by gas chromatography online analysis of hydrogen purity, and the drainage method is used to measure the hydrogen production rate, and the continuous operation is 26 h.

[0040] Example 3 The specific embodiment is the same as that of Example 1, except that the method for electrolyzing methanol to produce hydrogen by using the palladium-ruthenium nanoparticle nitrogen-doped carbon catalyst dynamically controlled by thermocouples comprises the following steps. First, the catalyst is prepared: 150 g of discarded crab shells are cleaned, crushed, and placed in a tube furnace, and carbonized at 604℃ at a rate of 10℃ / min under a nitrogen atmosphere for 4 h to obtain a primary carbonization product. The product is mixed with 35 g of melamine and ground, 12 g of zinc chloride is added, and the mixture is heated to 905℃ at a rate of 5℃ / min under an argon atmosphere and held for 2 h, then naturally cooled and soaked in 1 mol / L HCl solution for 6 h, then dried by dialysis to obtain a nitrogen-doped carbon carrier. 25 g of the nitrogen-doped carbon carrier is dispersed in 200 mL of ethylene glycol solution and ultrasonically treated for 4 h, 0.6 g of tetrachloropalladium acid and 0.35 g of ruthenium trichloride hydrate are weighed, 1.2 g of sodium citrate is added, and the mixture is irradiated in a microwave reactor at 182℃ for 20 min, then collected by centrifugation and dried at 60℃ under vacuum to obtain a precursor composite material. The material is pressed into a sheet and placed in a reaction chamber, high-purity argon is introduced, and a Nd:YAG laser is used to scan the surface of the material at a rate of 3.5 mm / s to obtain palladium-ruthenium heterojunction nanoclusters. 0.12 g of the nanoclusters after laser treatment is mixed with 1.2 g of polyaryl ether sulfone quaternary ammonium salt solution, coated on a carbon paper electrode, placed in 1 mol / L potassium hydroxide solution, and subjected to cyclic voltammetry activation treatment for 10 cycles at a scan rate of 50 mV / s, then washed with ultrapure water and dried at 64℃ under an argon atmosphere for 14 h. The electrolysis process: a three-dimensional flow channel electrolysis cell is made of transparent polycarbonate, and the anode chamber and the cathode chamber are separated by an anion exchange membrane. The prepared 0.6 g of catalyst is mixed with 0.12 g of polytetrafluoroethylene emulsion and roll-pressed into a 0.52 mm thick catalytic electrode sheet, which is hot-pressed with a titanium metal foam current collector to form a working electrode. The counter electrode is a stainless steel mesh loaded with 0.1 g of Pt / C catalyst, and the reference electrode is a mercury / mercury oxide electrode. A 0.12 mm diameter K-type armored thermocouple is embedded in the anode chamber to monitor the temperature of the catalyst layer, and three micro thin film thermocouples are arranged in the electrolyte flow channel. All signals are transmitted to the control system through a data acquisition card, the temperature deviation and deviation rate are calculated using fuzzy logic algorithm, the PID parameters are dynamically adjusted, the output signal drives the semiconductor refrigeration sheet to adjust the main body temperature of the cell, the micro piezoelectric ceramic pump pulses the pre-cooled methanol solution for micro cooling, and the pulse width modulation infrared heating lamp array compensates for heating at the edge of the electrode. The electrolyte is a mixture of 200 mL of methanol and 1 mol / L potassium hydroxide solution, which is first activated by cyclic voltammetry for 3 cycles, and then the system is started at a current density of 510 mA / cm². The temperature control system stably controls the interface micro zone temperature at 65.2℃, and every 40 min is switched to open circuit potential state for 11 s to eliminate concentration polarization. The hydrogen production rate is measured by gas chromatography online analysis of hydrogen purity, and the drainage method is used to measure the hydrogen production rate, and the continuous operation is 30 h.

[0041] Comparative Example 1 The specific implementation is the same as that of Example 1, except that no melamine is added during the preparation of the catalyst.

[0042] Comparative Example 2 The specific implementation is the same as that of Example 1, except that no zinc chloride is added during the preparation of the catalyst.

[0043] Comparative Example 3 The specific implementation is the same as that of Example 1, except that the dynamic thermocouple temperature control system is removed during the electrolysis process, and only a conventional constant temperature tank is used to control the bulk temperature of the electrolyte.

[0044] Performance Test The methanol electrolysis method of the Pd-Ru nanoparticle nitrogen-doped carbon catalyst with dynamic thermocouple temperature control in the above Examples 1-3 and Comparative Examples 1-3 is tested for performance according to the following method. The performance test method includes the following steps: The test is carried out at room temperature 25°C and normal pressure. The same size electrolytic tank and test equipment are used to ensure data comparability. The hydrogen production purity test uses an online gas chromatograph equipped with a thermal conductivity detector and a 13X molecular sieve column. The carrier gas is high-purity argon with a flow rate of 30 mL / min. The column oven temperature is set to 80°C, the detector temperature is 120°C, the sample size is 100 μL, and quantitative analysis is performed by external standard method. The hydrogen production rate test uses the drainage gas collection method. A precision 0.1 mL graduated gas collection cylinder is used to collect the gas. The gas production is recorded every 5 min. The average value within 1 h is taken as the final hydrogen production rate data. The system energy consumption is recorded by a precision DC power supply. The total power consumption is calculated to obtain the energy consumption value per unit of hydrogen production. The catalyst stability test is evaluated by continuously monitoring the potential change of the working electrode during the electrolysis process. The electrode potential under the working current density is recorded every 10 min to observe the trend over time. The electrolyte composition change is analyzed by high-performance liquid chromatography. The test conditions are as follows: C18 reverse-phase chromatographic column, mobile phase is acetonitrile water solution with a volume ratio of 10:90, flow rate is 1 mL / min, column temperature is 30°C, and detection wavelength is 210 nm. The catalyst microstructure characterization uses field emission scanning electron microscopy to observe the surface morphology at an acceleration voltage of 15 kV. X-ray diffractometer is used to analyze the crystal structure with copper target Kα radiation source, scanning range of 5-80 degrees and scanning speed of 5 degrees / min. Physical adsorption instrument is used to measure specific surface area and pore size distribution by nitrogen adsorption and desorption test at liquid nitrogen temperature 77 K. The temperature control accuracy of the electrolysis system is evaluated by calculating the standard deviation of the data collected by all thermocouples. The data of all four temperature measurement points are recorded every 10 s for 1 h. The degree of concentration polarization is analyzed by recording the current decay curve at the moment of switching to open circuit potential. The change of current with time under open circuit potential is recorded using an electrochemical workstation. All tests are repeated three times to take the average value as the final result.

[0045] Test results: Table 1: Test results of each example and comparative example

[0046] As can be seen from Table 1, examples 1-3 effectively solve the three core problems in the existing methanol electrolysis hydrogen production technology through innovative catalyst design and precise temperature control strategy. In terms of catalyst activity, the hydrogen production rate of examples 1-3 reaches 62.1-68.3 mL / min, far exceeding that of comparative example 1 (28.4 mL / min) and comparative example 2 (31.2 mL / min), which is mainly due to the nitrogen doping introduced by melamine (nitrogen content of examples 1-3 is 7.8-9.2 wt%, and that of comparative example 1 is only 1.2 wt%) and the developed pore structure formed by zinc chloride activation (specific surface area of examples 1-3 is 1180-1320 m² / g, and that of comparative example 2 is only 680 m² / g), which significantly improves the number of active sites and mass transfer efficiency. In terms of temperature control accuracy, examples 1-3 control the temperature fluctuation within ±0.12℃ through multi-thermocouple monitoring and fuzzy PID algorithm, while comparative example 3 uses a conventional constant temperature tank, and the temperature fluctuation reaches ±3.2℃, resulting in a hydrogen production rate of 45.6 mL / min and a 32.6% activity decay after 12 h of operation, which proves that the dynamic temperature control system is crucial to maintaining the stability of the reaction. In terms of long-term system operation, examples 1-3 have a continuous operation time of 26-30 h and an activity decay of only 7.8-9.5%, while comparative examples 1 and 2 have an activity decay of 40.5% and 35.2% after 15 h and 18 h of operation, respectively, due to the structural defects of the catalysts, indicating that the synergistic effect of nitrogen doping and pore structure effectively inhibits catalyst poisoning and deactivation. In addition, the unit hydrogen production energy consumption of examples 1-3 is 3.78-3.92 kWh / m 3 , which is significantly lower than that of comparative examples 1-3 (4.35-5.12 kWh / m 3 ), further verifying the advantages of this technical solution in improving energy efficiency. These results fully demonstrate that the present application realizes the simultaneous improvement of catalyst activity, temperature control accuracy and system stability through the synergistic effect of palladium ruthenium nanoparticles and nitrogen-doped carbon support, the enhancement of intrinsic activity by laser construction of heterojunction, and the elimination of local overheating by multi-stage temperature control strategy.

[0047] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the present patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with Pd-Ru nanoparticles and thermocouple-controlled dynamic temperature control, characterized in that, Includes the following steps: S1 is an electrolytic cell with a three-dimensional flow channel structure made of transparent polycarbonate. The anode chamber and the cathode chamber are separated by anion exchange membrane. Pd-Ru nanoparticle nitrogen-doped carbon catalyst is mixed evenly with polytetrafluoroethylene emulsion and rolled to form a catalytic electrode sheet with a microporous structure. The catalytic electrode sheet is hot-pressed and composited with titanium metal foam current collector to form a working electrode. The counter electrode is a stainless steel mesh loaded with Pt / C, and the reference electrode is a mercury / mercury oxide electrode. S2 integrates two types of thermocouples in the anode chamber: a K-type armored thermocouple is directly embedded inside the working electrode to monitor the catalyst layer temperature in real time; at the same time, three miniature thin-film thermocouples are arranged in the electrolyte flow channel parallel to the electrode surface, and all thermocouple signals are transmitted to the control system through a high-precision data acquisition card. S3, based on the collected temperature data, uses a fuzzy logic algorithm to calculate the temperature deviation and deviation change rate in real time, and dynamically adjusts the proportional, integral and derivative parameters of the PID controller; the output control signals drive the following actuators respectively: semiconductor cooling chip, micro piezoelectric ceramic pump, and pulse width modulation controlled infrared heating lamp array; S4, the electrolyte is a mixture of methanol and potassium hydroxide solution. After three cycles of cyclic voltammetry activation, the electrolysis system is started at a constant current density of 500-510 mA / cm². The temperature control system stabilizes the temperature of the electrode / electrolyte interface micro-region at 64.5-65.5℃. Every 30-40 minutes of operation, the system is switched to the open circuit potential state using a pulse method to eliminate concentration polarization. Hydrogen purity was analyzed online by gas chromatography, and the hydrogen production rate was measured by water displacement method, with continuous operation.

2. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with Pd-Ru nanoparticles under dynamic temperature control via thermocouple, as described in claim 1, is characterized in that... In step S1, the thickness of the catalytic electrode sheet is 0.5-0.52 mm.

3. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with thermocouple dynamic temperature control based on Pd-Ru nanoparticles according to claim 1, characterized in that, In step S2, the diameter of the K-type armored thermocouple is 0.1-0.12 mm.

4. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with thermocouple dynamic temperature control according to claim 1, characterized in that, In step S3, the semiconductor cooling chip acts on the outer wall of the electrolytic cell to regulate the main body temperature, the micro piezoelectric ceramic pump controls the pulse injection of pre-cooled methanol solution for local micro-area cooling, and the pulse width modulation controlled infrared heating lamp array compensates for heating the electrode edge area.

5. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with thermocouple dynamic temperature control according to claim 1, characterized in that, In step S4, the pulse method is used to switch to the open circuit potential state for 10-12 seconds, and the continuous operation time is 24-30 hours.

6. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with thermocouple dynamic temperature control according to any one of claims 1-5, characterized in that, The preparation steps of the Pd-Ru nanoparticle nitrogen-doped carbon catalyst include: A1. Waste crab shells are repeatedly washed with deionized water, crushed and sieved, and placed in a tube furnace and heated to 600-604℃ under a nitrogen atmosphere to obtain a primary carbonized product. The primary carbonized product is mixed and ground with melamine, zinc chloride is added, and the temperature is raised to 900-905℃ under argon protection and held. After natural cooling, it is soaked in HCl solution, and after dialysis and drying, a nitrogen-doped carbon support is obtained. A2, nitrogen-doped carbon support was dispersed in ethylene glycol solution and ultrasonically treated. Tetrachloropalladic acid and ruthenium trichloride hydrate were weighed, sodium citrate was added, and the mixture was irradiated in a microwave reactor at 178-182℃. After centrifugation and vacuum drying, the precursor composite material was obtained. A3, the precursor composite material was pressed into a sheet and placed in a reaction chamber. High-purity argon gas was introduced, and the surface of the material was scanned using an Nd:YAG laser to obtain Pd-Ru heterojunction nanoclusters. A4, the laser-treated Pd-Ru heterojunction nanoclusters are mixed with polyarylether sulfone quaternary ammonium salt solution, uniformly coated on carbon paper electrode, placed in potassium hydroxide solution for cyclic voltammetric activation treatment, and finally rinsed with ultrapure water and dried at 60-64℃ in argon atmosphere.

7. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with thermocouple dynamic temperature control according to claim 6, characterized in that, In step A1, the carbonization time at 600-604℃ is 2-4 hours; the holding time at 900-905℃ is 1-2 hours.

8. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with thermocouple dynamic temperature control according to claim 6, characterized in that, In step A2, the ultrasonic treatment time is 2-4 hours; the radiation treatment time at 178-182℃ is 15-20 minutes.

9. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with Pd-Ru nanoparticles and thermocouple dynamic temperature control according to claim 6, characterized in that, In step A3, the scanning rate is 2-4 mm / s.

10. The method for producing hydrogen from methanol by electrolysis using a nitrogen-doped carbon catalyst with thermocouple dynamic temperature control according to claim 6, characterized in that, In step A4, the drying time at 60-64℃ is 12-14 hours.

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