Hydrogen production process and device using concentrated solar energy for water vapor

Abstract

The application relates to the technical field of photocatalytic water decomposition hydrogen production, in particular to a light-gathering heat-storing water vapor hydrogen production process and device. The light-gathering heat-storing water vapor hydrogen production process comprises the following steps: liquid water enters a light-gathering reactor through a raw material sampling device, is vaporized into water vapor in the light-gathering reactor, is mixed with inert gas which is introduced through a carrier gas gas path, sequentially passes through a first catalyst filling layer and a second catalyst filling layer in a reaction zone, and then enters a gas-liquid separation device located at the lower end of the light-gathering reactor; unreacted water vapor is condensed and liquefied through the gas-liquid separation device, the generated gas product is separated and discharged together with the inert gas, is decompressed through a back pressure valve, is dehydrated through a drying unit, and finally the product hydrogen gas is obtained. The application provides a light-gathering heat-storing water vapor hydrogen production process and device, so as to solve the problems of high energy consumption, insufficient catalyst stability and activity in the related art.

Description

Technical Field

[0001] This application relates to the field of photocatalytic water splitting for hydrogen production technology, and in particular to a concentrated solar thermal storage steam hydrogen production process and apparatus. Background Technology

[0002] Currently, with continuous social development, energy consumption demand is constantly increasing. The world's energy supply still relies heavily on traditional fossil fuels, leading to increasingly severe environmental problems. A green and low-carbon energy transition is urgently needed. Therefore, there is an urgent need to accelerate the utilization of renewable energy sources such as solar energy. Hydrogen energy, as a highly efficient and clean energy source, is attracting increasing attention. Hydrogen energy is very convenient to store and transport; it can serve as an important means of large-scale, long-term energy storage and can be applied in various scenarios, making it a key carrier for the effective coupling of clean energy systems. The utilization of hydrogen energy has the potential to reduce global carbon emissions from energy consumption by more than half. If solar energy can be effectively converted into hydrogen energy through solar-powered hydrogen production, large-scale, long-term storage and transportation of solar energy can be effectively achieved.

[0003] In existing technologies, photothermal catalytic water splitting for hydrogen production is mostly conducted in liquid-phase systems, which have significant drawbacks: catalyst films are prone to detachment or ionic dissolution in solution, catalysts in suspended systems are prone to aggregation, reverse reactions are severe, and scale-up of photoreactors is demanding and difficult to design. However, if photothermal catalytic water splitting for hydrogen production is a gas-solid reaction, these problems can be solved. There is no catalyst detachment issue, the reaction is more stable, reverse reactions can be suppressed, and large-scale photoreactor design is easier: gas introduction can easily achieve uniform distribution of water reactants, and it is easier to establish high-pressure photocatalytic reactors. For steam hydrogen production, the drawback is the need for high-temperature conditions and high energy consumption. Therefore, the selection of catalysts and their reaction environment and conditions are crucial, and their activity and stability at high temperatures must be considered. Therefore, developing a photothermal catalytic water steam splitting process for hydrogen production, along with a corresponding reaction device and catalyst, is particularly necessary. Summary of the Invention

[0004] This application provides a concentrated solar thermal storage steam hydrogen production process and apparatus to solve the problems of high energy consumption and insufficient catalyst stability and activity in related technologies.

[0005] In one aspect, a concentrated solar thermal storage steam hydrogen production process is provided, which includes the following steps:

[0006] Liquid water enters the concentrating reactor through the raw material feeding device and is vaporized into water vapor in the concentrating reactor;

[0007] The inert gas enters the concentrating reactor through the carrier gas path and mixes with the water vapor entering the concentrating reactor;

[0008] Inert gas and water vapor are mixed and then flow sequentially through the first catalyst packing layer and the second catalyst packing layer under concentrated light irradiation to react. The resulting hydrogen gas is then processed by a gas-liquid separation device.

[0009] The first catalyst filling layer is filled with a first catalyst, and the second catalyst filling layer is filled with a second catalyst.

[0010] The first catalyst is prepared by the following steps:

[0011] S101. Preparation of pretreated gel: Immerse silica aerogel in 5wt% hydrofluoric acid solution for 1-1.5h, wash with deionized water until neutral, dry at 100-120℃ for 2-3h, and then calcine at 400-450℃ for 2-2.5h to obtain pretreated aerogel.

[0012] S102, Active ingredient loading: SrCl2, Al2O3 and SrTiO3 were mixed in a molar ratio of 10:0.02:1, calcined at 1000℃ for 10 h, washed with deionized water, and then vacuum dried at 60~80℃ for 12 h to obtain aluminum-doped strontium titanate;

[0013] Strontium titanate doped with aluminum was dissolved in a solvent and sonicated for 30 minutes, followed by stirring for 2 hours to obtain a mixture. The solvent consisted of deionized water and isopropanol in a volume ratio of 4:1, and the mass-volume ratio of strontium titanate doped with aluminum to the solvent was (0.2~0.25):10.

[0014] The pretreated aerogel is immersed in the mixture, stirred in a water bath at 50-60°C for 2-3 hours, allowed to stand for 4-5 hours, filtered, washed with deionized water, dried at 100-110°C for 8-8.5 hours, and calcined at 450-480°C for 2-2.5 hours to complete the loading of active ingredients and obtain active ingredient loaded aerogel.

[0015] S103, Surface modification: The active ingredient-supported aerogel is mixed and stirred with a transition metal aqueous solution for 1.5-2 hours, then the water is evaporated in an oil bath at 80°C, and then vacuum dried at 90-100°C for 6-7 hours to obtain the first catalyst.

[0016] Preferably, in step S103, the transition metal aqueous solution comprises a transition metal compound and deionized water, wherein the transition metal compound comprises Co3O4, RhCl3·6H2O, and K2CrO4, and the mass ratio of Co3O4, RhCl3·6H2O, K2CrO4 to deionized water is (0.2~0.5):0.1:(0.2~0.5):100;

[0017] The mass ratio of the active ingredient-loaded aerogel to the transition metal aqueous solution is 1:(8~10).

[0018] Preferably, the method for preparing Co3O4 includes the following steps:

[0019] CoCl2·6H2O was dissolved in ethylene glycol and stirred until completely dissolved. Then NaOH was added, followed by polyvinylpyrrolidone K30 and oxalic acid under vigorous stirring. The mixture was reacted in an oven at 180°C for 18 h and then calcined in air at 400°C for 3 h to obtain Co3O4.

[0020] The mass-to-volume ratio of CoCl2·6H2O to ethylene glycol is 1g:20mL, the molar ratio of NaOH, oxalic acid and CoCl2·6H2O is 5:1:1, and the mass of polyvinylpyrrolidone K30 added is 1 to 2 times the mass of CoCl2·6H2O.

[0021] Preferably, the preparation method of the second catalyst includes the following steps:

[0022] S201. Preparation of pretreated carrier: After mixing MAB phase powder with 5wt% hydrofluoric acid solution, react at 45~50℃ for 1~2h, wash with deionized water until neutral, dry at 110~120℃ for 6~8h, compress into tablets at 20MPa, and break into 2~4mm particles to obtain pretreated carrier.

[0023] S202, Active component loading: Nickel nitrate and cobalt nitrate are mixed at a molar ratio of 2:1, and then trisodium citrate, ethylene glycol, and deionized water are added and stirred to obtain a sol; the molar ratio of trisodium citrate to metal ions is 1:1, the amount of ethylene glycol and deionized water added is such that the concentration of metal ions is 0.3 mol / L, and the mass ratio of ethylene glycol to water is 1:3;

[0024] The pretreated carrier is mixed with sol, ultrasonically treated for 20-30 min, dried at 75-80℃, and then calcined at 480-500℃ for 2-3 h to obtain the active ingredient loading carrier.

[0025] S203, Composite Modification: Cerium oxide powder is dispersed in anhydrous ethanol at a mass ratio of 1:20, ultrasonically treated for 20-30 min, lithium stearate and manganese nitrate are added, and then the active ingredient support is added. The mixture is rotary evaporated at 48-50℃, dried at 110-120℃ for 1-2 h, and calcined at 560-600℃ for 2-3 h to obtain the second catalyst.

[0026] The mass ratio of the active ingredient support carrier to cerium oxide, lithium stearate, and manganese nitrate is 2:1:0.1:0.5.

[0027] Preferably, the thickness of the first catalyst filling layer is 1~5 mm, and the effective filling volume is 0.1~0.5 mL;

[0028] The second catalyst filling layer has a filling thickness of 1~4 mm and an effective filling volume of 0.1~0.5 mL.

[0029] Preferably, the volume ratio of water vapor to inert gas is 1:(5~20), the reaction temperature of the first catalyst filling layer is 300~500℃, and the reaction temperature of the second catalyst filling layer is 300~400℃.

[0030] Preferably, in the carrier gas path, the gas flow rate is no greater than 300 NmL / min, and the pressure is 0.1~3.0 MPa.

[0031] Preferably, in the raw material injection device, the flow rate of liquid water is 0.002~5 NmL / min, and the pressure is not less than 3MPa.

[0032] A concentrated solar thermal storage steam hydrogen production device, the device comprising:

[0033] The carrier gas path includes a carrier gas cylinder, a pressure gauge, a pressure reducing valve, and a gas mass flow meter;

[0034] A raw material injection device, comprising a storage tank, a liquid check valve, a precision liquid high-pressure pump, an injection check valve, and a check valve;

[0035] A concentrating reactor includes a concentrating system and a reaction system. The concentrating system includes a sunlight receiver, a convex lens, and a viewing window. The reaction system includes a stainless steel shell, a quartz tube, and an upper heating zone, a reaction zone, and a water vaporization zone formed from top to bottom in the quartz tube. The upper heating zone is used for gas mixing. The reaction zone is provided with a first catalyst filling layer and a second catalyst filling layer. Temperature sensors for the upper heating zone, the reaction zone, and the water vaporization zone are respectively provided in the upper heating zone, the reaction zone, and the water vaporization zone. The concentrating system guides light to the first catalyst filling layer through a light guide column.

[0036] A gas-liquid separation device, comprising a gas-liquid separation tank, a liquid separation check valve, a back pressure valve, and a drying unit.

[0037] Preferably, it further includes a first thermocouple for monitoring the temperature of the first catalyst packing layer and a second thermocouple for monitoring the temperature of the second catalyst packing layer.

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

[0039] This application provides a concentrated solar thermal storage steam hydrogen production process and apparatus, which uses two catalysts. The first catalyst is located below the concentrated solar system and directly receives light from the system. Due to the direct light exposure, the high temperature generated by the light further enhances the activity of the catalyst. The first catalyst lowers the activation energy of the reaction and selectively catalyzes the reaction pathway, reducing the occurrence of side reactions and improving the selectivity of the reaction. This allows the reaction to proceed more efficiently at a relatively lower temperature, thereby increasing the yield and purity of hydrogen. The first catalyst utilizes the direct heat generated by the concentrated light to photocatalytically dissociate and generate initial H2 and active intermediates. The second catalyst relies on heat conduction to carry out deep conversion in succession. The two catalysts are used in a progressive manner, allowing steam hydrogen production to proceed from high activation energy to low activation energy, thus reducing overall energy consumption. Attached Figure Description

[0040] 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.

[0041] Figure 1 A schematic diagram of the apparatus provided in this application for realizing a steam-to-hydrogen process for concentrated solar thermal storage;

[0042] Figure 2 The method flow for preparing the first catalyst for realizing the steam hydrogen production process of concentrated solar thermal storage provided in this application;

[0043] Figure 3 The present application provides a method flow for preparing a second catalyst for realizing a concentrated solar thermal storage process for hydrogen production using steam.

[0044] In the diagram: Ⅰ. Carrier gas path; Ⅱ. Raw material injection device; Ⅲ. Concentrating reactor; Ⅳ. Gas-liquid separation device; 1. Carrier gas cylinder; 2. Pressure gauge; 3. Pressure reducing valve; 4. Flow meter; 5. Light beam; 6. Sunlight receiver; 7. Convex lens; 8. Viewing window; 9. Upper heating zone; 10. Reaction zone; 11. Water vaporization zone; 12. Light guide column; 13. First catalyst packing layer; 14. Upper heating zone temperature sensor; 15. Reaction zone temperature sensor; 16. Water vaporization zone temperature sensor; 17. Liquid storage tank; 18. Liquid check valve; 19. Precision liquid high-pressure pump; 20. Injection check valve; 21. Check valve; 22. First thermocouple; 23. Gas-liquid separation tank; 24. Liquid separation check valve; 25. Back pressure valve; 26. Drying unit; 27. Stainless steel shell; 28. Quartz tube; 29. ​​Second catalyst packing layer; 30. Second thermocouple. Detailed Implementation

[0045] 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.

[0046] See Figures 1-3 As shown, this application provides a process and apparatus for hydrogen production from concentrated solar thermal energy storage using steam.

[0047] Example 1

[0048] The concentrated solar thermal storage steam hydrogen production process provided in this embodiment includes the following steps:

[0049] Liquid water enters the concentrating reactor III through the raw material feeding device II. In the concentrating reactor III, it is vaporized into water vapor and then mixed with the inert gas introduced through the carrier gas passage I. It then passes through the first catalyst filling layer 13 and the second catalyst filling layer 29 in the reaction zone 10 in sequence, and then enters the gas-liquid separation device IV located at the lower end of the concentrating reactor III. The unreacted water vapor is condensed and liquefied by the gas-liquid separation tank 23 of the gas-liquid separation device IV. The generated gaseous product is separated and discharged with the inert gas, then depressurized by the back pressure valve 25, and then dehydrated by the drying unit 26 to obtain the product hydrogen.

[0050] Among them, the concentrating reactor III includes a concentrating system and a reaction system. The concentrating system includes a solar receiver 6, a convex lens 7 and a viewing window 8. The reaction system includes an upper heating zone 9, a reaction zone 10 and a water vaporization zone 11 arranged sequentially along the gas conveying direction. The upper heating zone 9 of the concentrating system and the reaction system are connected by a light guide column 12.

[0051] Along the gas transport direction, the first catalyst filling layer 13 is located below the focusing system, and the second catalyst filling layer 29 is located below the first catalyst filling layer 13. The first catalyst filling layer 13 is filled with a first catalyst, and the preparation method of the first catalyst includes the following steps:

[0052] S101. Preparation of pretreated gel: 15g of silica aerogel was immersed in 150g of 5wt% hydrofluoric acid solution for 1h, washed with deionized water until neutral, dried at 120℃ for 3h, and then calcined at 450℃ for 2h to obtain pretreated aerogel.

[0053] S102, Active ingredient loading: SrCl2 (10 mmol), Al2O3 (0.02 mmol) and SrTiO3 (1 mmol) were mixed, calcined at 1000℃ for 10 h, washed with deionized water, and then vacuum dried at 80℃ for 12 h to obtain aluminum-doped strontium titanate;

[0054] 1g of aluminum-doped strontium titanate was dissolved in a solvent and sonicated for 30 minutes, followed by stirring for 2 hours to obtain a mixture, wherein the solvent was a mixture of 40mL deionized water and 10mL isopropanol.

[0055] 14g of pretreated aerogel was immersed in 35mL of mixed solution, stirred in a 60℃ water bath for 3h, allowed to stand for 5h, filtered, washed with deionized water, dried at 110℃ for 8h, and calcined at 480℃ for 2h to complete the loading of active ingredients and obtain active ingredient loaded aerogel.

[0056] S103, Surface modification: 10g of active ingredient-supported aerogel was mixed with 100g of transition metal aqueous solution and stirred for 2h. The water was evaporated in an oil bath at 80℃ and then vacuum dried at 90℃ for 6h to obtain the first catalyst.

[0057] The transition metal aqueous solution is a mixture of 0.5g Co3O4, 0.1g RhCl3·6H2O, 0.5g K2CrO4 and 100g deionized water.

[0058] The preparation method of Co3O4 includes the following steps:

[0059] 2 g of CoCl2·6H2O was dissolved in 40 mL of ethylene glycol and stirred until completely dissolved. Then, 0.168 g of NaOH was added. Next, 2.5 g of polyvinylpyrrolidone K30 and 0.076 g of oxalic acid were added under vigorous stirring. The mixture was reacted in an oven at 180 °C for 18 h, and then calcined in air at 400 °C for 3 h to obtain Co3O4.

[0060] The second catalyst filling layer 29 is filled with a second catalyst, and the preparation method of the second catalyst includes the following steps:

[0061] S201. Preparation of pretreated carrier: 15g of Ti3AlB2 powder was mixed with 150g of 5wt% hydrofluoric acid solution and reacted at 50℃ for 2h. The mixture was washed with deionized water until neutral and dried at 120℃ for 8h. After being pressed into tablets at 20MPa, the tablets were crushed into 2~4mm particles to obtain the pretreated carrier.

[0062] S202, Active component loading: Mix 4.65g nickel nitrate and 2.33g cobalt nitrate, then add 2.19g trisodium citrate, 8g ethylene glycol, and 24g deionized water, and stir to obtain a sol;

[0063] 12g of pretreated carrier was mixed with sol, ultrasonicated for 30min, dried at 80℃, and then calcined at 500℃ for 3h to obtain the active ingredient loading carrier.

[0064] S203, Composite Modification: 7.6g of cerium oxide powder was dispersed in 152g of anhydrous ethanol, ultrasonically treated for 30min, then 0.76g of lithium stearate and 3.8g of manganese nitrate were added, followed by 15.2g of active ingredient support. The mixture was rotary evaporated at 50℃, dried at 120℃ for 2h, and calcined at 600℃ for 3h to obtain the second catalyst.

[0065] Example 2

[0066] The concentrated solar thermal storage steam hydrogen production process provided in this embodiment includes the following steps:

[0067] Liquid water enters the concentrating reactor III through the raw material feeding device II. In the concentrating reactor III, it is vaporized into water vapor and then mixed with the inert gas introduced through the carrier gas passage I. It then passes through the first catalyst filling layer 13 and the second catalyst filling layer 29 in the reaction zone 10 in sequence, and then enters the gas-liquid separation device IV located at the lower end of the concentrating reactor III. The unreacted water vapor is condensed and liquefied by the gas-liquid separation tank 23 of the gas-liquid separation device IV. The generated gaseous product is separated and discharged with the inert gas, then depressurized by the back pressure valve 25, and then dehydrated by the drying unit 26 to obtain the product hydrogen.

[0068] The concentrating reactor III includes a concentrating system and a reaction system. The concentrating system includes a solar receiver 6, a convex lens 7, and a viewing window 8. The reaction system includes an upper heating zone 9, a reaction zone 10, and a water vaporization zone 11 arranged sequentially along the gas conveying direction. The upper heating zone 9 of the concentrating system and the reaction system are connected by a light guide column 12.

[0069] Along the gas transport direction, the first catalyst filling layer 13 is located below the focusing system, and the second catalyst filling layer 29 is located below the first catalyst filling layer 13. The first catalyst filling layer 13 is filled with a first catalyst, and the preparation method of the first catalyst includes the following steps:

[0070] S101. Preparation of pretreated gel: 15g of silica aerogel was immersed in 150g of 5wt% hydrofluoric acid solution for 1.5h, washed with deionized water until neutral, dried at 100℃ for 3h, and then calcined at 400℃ for 2.5h to obtain pretreated aerogel.

[0071] S102, Active ingredient loading: SrCl2 (10 mmol), Al2O3 (0.02 mmol) and SrTiO3 (1 mmol) were mixed, calcined at 1000℃ for 10 h, washed with deionized water, and then vacuum dried at 60℃ for 12 h to obtain aluminum-doped strontium titanate;

[0072] 1g of aluminum-doped strontium titanate was dissolved in a solvent and sonicated for 30 minutes, followed by stirring for 2 hours to obtain a mixture, wherein the solvent was a mixture of 32mL deionized water and 8mL isopropanol.

[0073] 14g of pretreated aerogel was immersed in 35mL of mixed solution, stirred in a 50℃ water bath for 2h, allowed to stand for 5h, filtered, washed with deionized water, dried at 100℃ for 8.5h, and calcined at 450℃ for 2.5h to complete the loading of active ingredients and obtain active ingredient loaded aerogel.

[0074] S103, Surface modification: 10g of active ingredient-supported aerogel was mixed with 80g of transition metal aqueous solution and stirred for 2h. The water was evaporated in an oil bath at 80℃ and then vacuum dried at 90℃ for 6h to obtain the first catalyst.

[0075] The transition metal aqueous solution is a mixture of 0.2g Co3O4, 0.1g RhCl3·6H2O, 0.2g K2CrO4 and 100g deionized water.

[0076] The preparation method of Co3O4 is the same as in Example 1, except that the amount of polyvinylpyrrolidone K30 added is 2g.

[0077] The second catalyst filling layer 29 is filled with a second catalyst, and the preparation method of the second catalyst includes the following steps:

[0078] S201. Preparation of pretreated carrier: 15g of Ti3AlB2 powder was mixed with 150g of 5wt% hydrofluoric acid solution and reacted at 45℃ for 1h. The mixture was washed with deionized water until neutral and dried at 110℃ for 6h. After being pressed into tablets at 20MPa, the tablets were crushed into 2~4mm particles to obtain the pretreated carrier.

[0079] S202, Active component loading: Mix 4.65g nickel nitrate and 2.33g cobalt nitrate, then add 2.19g trisodium citrate, 8g ethylene glycol, and 24g deionized water, and stir to obtain a sol;

[0080] 12g of pretreated carrier was mixed with sol, ultrasonicated for 20min, dried at 75℃, and then calcined at 480℃ for 2h to obtain the active ingredient loading carrier.

[0081] S203, Composite Modification: 7.6g of cerium oxide powder was dispersed in 152g of anhydrous ethanol, ultrasonically treated for 20min, then 0.76g of lithium stearate and 3.8g of manganese nitrate were added, followed by 15.2g of active ingredient support. The mixture was rotary evaporated at 48℃, dried at 110℃ for 1h, and calcined at 560℃ for 2h to obtain the second catalyst.

[0082] Example 3

[0083] This embodiment provides an apparatus for realizing a steam-to-hydrogen process for concentrated solar thermal storage.

[0084] See Figure 1 As shown, it includes a carrier gas path I, a raw material injection device II, a focusing reactor III, and a gas-liquid separation device IV. The focusing reactor III includes a focusing system and a reaction system. The focusing system includes a sunlight receiver 6, a convex lens 7, and a viewing window 8. The reaction system includes a stainless steel casing 27, a quartz tube 28, and, from top to bottom, an upper heating zone 9, a reaction zone 10, and a water vaporization zone 11 formed at the top of the quartz tube 28. After receiving sunlight, the sunlight receiver 6 focuses it through the convex lens 7 and passes through the viewing window 8 and the light guide column 12 to reach the first catalyst filling layer 13. Alternatively, the focusing system can be disassembled, and a xenon lamp can be used directly as the light source.

[0085] Carrier gas path I is connected to concentrating reactor III. Light 5 passes through the concentrating system window 8 and light guide column 12 to reach the surface of the first catalyst filling layer 13. The surface of the first catalyst filling layer 13 is connected to the first thermocouple 22 for temperature measurement, while the second catalyst filling layer 29 is connected to the second thermocouple 30 for temperature measurement. Raw material injection device II is connected to the water vaporization zone 11 in concentrating reactor III, which is also connected to the first catalyst filling layer 13 in reaction zone 10. Concentrating reactor III is connected to the gas-liquid separation tank 23 of gas-liquid separation device IV. The top of gas-liquid separation tank 23 is connected to drying unit 26 through back pressure valve 25. Drying unit 26 is used to remove water, finally obtaining hydrogen and oxygen as generated gases. Liquid is discharged from the bottom of gas-liquid separation tank 23 through liquid separation check valve 24.

[0086] Meanwhile, the carrier gas path I includes a carrier gas cylinder 1, which is connected to a pressure gauge 2. The pressure gauge 2 is connected to a pressure reducing valve 3, which is connected to a gas mass flow meter 4, and the gas mass flow meter 4 is connected to reactor I.

[0087] The raw material injection device II includes a storage tank 17, which is connected to a liquid check valve 18. The liquid check valve 18 is connected to a precision liquid high-pressure pump 19, and the flow rate of liquid water is precisely controlled by the precision liquid high-pressure pump 19. The precision liquid high-pressure pump 19 is connected to an injection check valve 20, and the injection check valve 20 is connected to a check valve 21.

[0088] The reaction system includes a stainless steel casing 27, a quartz tube 28, an upper heating zone 9, a reaction zone 10, a water vaporization zone 11, and a light guide column 12. The stainless steel casing 27 is fitted over the quartz tube 28. The upper heating zone 9 connects to the reaction zone 10, and the reaction zone 10 connects to the water vaporization zone 11. Along the gas transport direction, the focusing system, upper heating zone 9, reaction zone 10, and water vaporization zone 11 are arranged sequentially. Liquid water is transported by a precision high-pressure liquid pump 19 and then enters the side branch pipe connected to the focusing reactor III for preheating and vaporization. (See [reference]). Figure 1 As shown, the side branch is spirally sleeved on the part of the quartz tube 28 located in the water vaporization zone 11. The heated and vaporized water vapor passes through the injection check valve 20 and the check valve 21 in sequence, and enters the concentrator III directly from the top of the quartz tube 28. It mixes with the inert gas introduced through the carrier gas passage I and enters the quartz tube 28 of the concentrator III. After reacting on the surface of the first catalyst filling layer 13, it enters the second catalyst filling layer 29. The two catalyst filling layers are located inside the quartz tube 28. The inner diameter of the quartz tube 28 is 12 mm. The filling thickness of the first catalyst is 5 mm and the effective filling volume is 0.5 mL. The filling thickness of the second catalyst is 4 mm and the effective filling volume is 0.5 mL. The internal pressure of the concentrator III can be controlled by the connected back pressure valve 25. The pressure is 2 MPa.

[0089] The upper heating zone 9, reaction zone 10, and water vaporization zone 11 of the concentrating reactor III are individually heated and temperature-controlled using heating wires. Temperature sensors 14 (upper heating zone), 15 (reaction zone), and 16 (water vaporization zone) are connected to these sensors respectively to monitor the temperature of the three zones in real time. The heating wires can be temperature-controlled within the range of 0~800℃. (See [reference]). Figure 1 As shown, the side branch pipe connected to the concentrating reactor III is arranged in a spiral upward manner in the water vaporization zone 11, so that the liquid water in the side branch pipe is fully vaporized after being heated at high temperature in the water vaporization zone 11 and successfully enters the upper heating zone 9. In addition, these three zones of the concentrating reactor III also have a heat storage layer and a heat insulation layer, so as to realize heat storage and heat preservation under concentrated light, enabling the concentrating reactor III to use thermal energy to perform thermocatalytic decomposition of water vapor to produce hydrogen in the absence of sunlight.

[0090] In the concentrating reactor III, the temperatures of the upper heating zone 9, reaction zone 10, and water vaporization zone 11 are controlled at 200℃, 300℃, and 150℃, respectively. Furthermore, the temperatures of the first catalyst filling layer 13 and the second catalyst filling layer 29 in reaction zone 10 are individually controlled, with the temperature of the first catalyst filling layer 13 ranging from 300 to 500℃ and the temperature of the second catalyst filling layer 29 ranging from 300 to 400℃. This means that the concentrating reactor III can simultaneously achieve both concentrated light and external heating, and can also utilize concentrated light alone for photothermal decomposition of water vapor to produce hydrogen. During the reaction, heat can be stored in the heat storage layer and insulation layer of the concentrating reactor III. Under conditions of no sunlight, the stored heat energy can be used to decompose water vapor to produce hydrogen; for example, concentrated photothermal decomposition of water vapor to produce hydrogen can be carried out during the day, and the stored heat energy can be used at night. Simultaneously, external heating can be used for the reaction, which to some extent solves the problem of solar energy fluctuations. If a photothermal decomposition of water vapor to produce hydrogen under pressurized conditions is required, the reaction pressure inside the concentrator reactor III can be controlled by the back pressure valve 25 and can be adjusted within 2 MPa.

[0091] The gas-liquid separation device IV includes a gas-liquid separation tank 23, a liquid separation check valve 24, a back pressure valve 25, and a drying unit 26. The upper end of the gas-liquid separation tank 23 is connected to the lower end of the concentrating reactor III. The gas-liquid separation tank 23 is connected to the back pressure valve 25. Unreacted water vapor condenses and liquefies, and is discharged through the liquid separation check valve 24. The generated gaseous product is separated and discharged with the inert gas and then depressurized through the back pressure valve 25. At the same time, the other end of the back pressure valve 25 is connected to the drying unit 26 to remove water and obtain the product hydrogen.

[0092] Example 4

[0093] See Figure 1 As shown, the specific process is as follows: The quartz tube 28 is removed, and the first catalyst and the second catalyst are uniformly filled into the first catalyst filling layer 13 and the second catalyst filling layer 29, respectively. Quartz wool is used to separate the first catalyst filling layer 13 and the second catalyst filling layer 29, and both ends of the catalyst are filled with 20-mesh quartz sand to prevent catalyst loss due to airflow disturbance. The catalyst filling thickness is 3 mm, the effective filling volume is 0.5 mL, and the bulk density is 1.2 g / mL. After filling the catalyst, the entire quartz tube 28 is inserted into the stainless steel outer shell 27 of the concentrating reactor III, and the quartz tube 28 is tightened and sealed to the stainless steel outer shell 27. The first thermocouple 22 and the second thermocouple 30 are then inserted to complete the catalyst filling.

[0094] Inert gas Ar enters the concentrating reactor III from the carrier gas cylinder 1 via pressure gauge 2 and pressure reducing valve 3, and reaches the gas mass flow meter 4 through the gas path. The gas flow rate is controlled to be 300 NmL / min. At the same time, water vapor and inert gas are controlled to enter the concentrating reactor III at a volume ratio of 1:9. In addition, air in the concentrating reactor III is removed by inert gas Ar before the reaction.

[0095] Water in storage tank 17 enters precision liquid high-pressure pump 19 through liquid check valve 18. Precision liquid high-pressure pump 19 controls the flow rate of liquid water, maintaining a flow rate of 5 NmL / min and a pressure of 3.5MPa with an accuracy of 1%. Water passing through precision liquid high-pressure pump 19 enters water vaporization zone 11 (150℃) in concentrating reactor III at this flow rate via injection check valve 20 and check valve 21. The side branch pipe connected to concentrating reactor III is arranged in a spiral upward manner in water vaporization zone 11, allowing the liquid water to fully vaporize. Finally, it enters concentrating reactor III and mixes with inert gas Ar, controlling the water vapor volume fraction to be 30%. The temperatures of upper heating zone 9, reaction zone 10, and water vaporization zone 11 are controlled at 200℃, 300℃, and 150℃, respectively.

[0096] The temperature of the first catalyst filling layer 13 and the second catalyst filling layer 29 is further controlled by heating wires, wherein the temperature of the first catalyst filling layer 13 is 500°C and the temperature of the second catalyst filling layer 29 is 400°C.

[0097] Sunlight is received by sunlight receiver 6, then focused by convex lens 7. The focused sunlight passes through sapphire window 8 and light guide column 12 to reach the surface of first catalyst filling layer 13 for catalytic reaction, and then enters second catalyst filling layer 29 for secondary catalysis.

[0098] The first catalyst and the second catalyst prepared in Example 1 and Example 2 were tested according to the process provided in Example 4.

[0099] Sampling and analysis were started 30 minutes after the reaction stabilized, with sampling every 30 minutes for 5 hours.

[0100] After 5 hours, the reaction conditions were kept unchanged and the test was continued for 100 hours, with samples taken and analyzed every 10 hours to record the changes in the activity of the two catalysts. After the test, the total mass loss rate of the two catalysts was calculated, and carbon deposition analysis was performed on the catalysts.

[0101] The hydrogen yield is calculated as follows:

[0102] ;

[0103] After reacting continuously for 100 hours under the above yield test conditions, the catalyst was recovered, and the mass loss rate was measured.

[0104] ;

[0105] Take 0.1 g of each of the two catalysts after 100 h of reaction, and heat them together in a TGA at 10 °C / min to 800 °C (air atmosphere, 50 mL / min). Record the weight loss rate (weight loss due to carbon deposition oxidation) in the 600~800 °C range.

[0106] ;

[0107] See Table 1, where Comparative Example 1 is an example of not using the second catalyst (the filler of the second catalyst filling layer 29 was replaced with quartz wool).

[0108] Table 1

[0109]

[0110] It should be noted that the hydrogen yield and stability of Examples 1 and 2 above are based on the combined effect of the first catalyst and the second catalyst.

[0111] Comparing with Comparative Example 1, Examples 1 and 2 use two catalysts. The first catalyst directly receives light to react, while the second catalyst does not directly contact light and can capture the intermediate products that are not completely converted by the first catalyst, and further generate H2 through a secondary reaction, thereby improving the overall yield.

[0112] The first catalyst is first etched with hydrofluoric acid to increase the porosity and number of hydroxyl groups on the aerogel surface, thereby improving its adsorption performance. Subsequently, active components are loaded: SrTiO3 acts as a photoresponsive material to enhance the hydrogen production rate, SrCl2 optimizes the electronic structure of the aerogel surface and reduces the energy barrier for water vapor decomposition, and the transition metal aqueous solution further provides active sites for hydrogen production. Combined with the high light transmittance and porous structure of the aerogel, light energy is efficiently converted into heat energy, ensuring continuous and efficient operation under illumination conditions.

[0113] The second catalyst uses the MAB phase as a support, loads Ni-Co bimetallic active components, and is modified by a cerium oxide / manganese nitrate composite. It is located below the first catalyst and receives the conducted heat. The synergistic effect of the Ni-Co bimetallic components deeply dissociates the water vapor that is not completely converted by the first catalyst, thereby increasing the total hydrogen yield; at the same time, the composite modification of manganese nitrate and lithium stearate enhances the oxygen storage capacity.

[0114] The concentrated solar thermal storage steam hydrogen production process and corresponding steam hydrogen production device provided in this application involve multiple processes such as concentration, heat transfer, and electrolysis, which improves the overall hydrogen production efficiency and stability.

[0115] 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 producing hydrogen from concentrated solar power (CSP) steam, characterized in that, It includes the following steps: Liquid water enters the concentrating reactor through the raw material feeding device and is vaporized into water vapor in the concentrating reactor; The inert gas enters the concentrating reactor through the carrier gas path and mixes with the water vapor entering the concentrating reactor; Inert gas and water vapor are mixed and then flow sequentially through the first catalyst packing layer and the second catalyst packing layer under concentrated light irradiation to react. The resulting hydrogen gas is then processed by a gas-liquid separation device. The first catalyst filling layer is filled with a first catalyst, and the second catalyst filling layer is filled with a second catalyst. The first catalyst is prepared by the following steps: S101. Preparation of pretreated gel: Immerse silica aerogel in 5wt% hydrofluoric acid solution for 1-1.5h, wash with deionized water until neutral, dry at 100-120℃ for 2-3h, and then calcine at 400-450℃ for 2-2.5h to obtain pretreated aerogel. S102, Active ingredient loading: SrCl2, Al2O3 and SrTiO3 were mixed in a molar ratio of 10:0.02:1, calcined at 1000℃ for 10 h, washed with deionized water, and then vacuum dried at 60~80℃ for 12 h to obtain aluminum-doped strontium titanate; Strontium titanate doped with aluminum was dissolved in a solvent and sonicated for 30 minutes, followed by stirring for 2 hours to obtain a mixture. The solvent consisted of deionized water and isopropanol in a volume ratio of 4:1, and the mass-volume ratio of strontium titanate doped with aluminum to the solvent was (0.2~0.25):

10. The pretreated aerogel is immersed in the mixture, stirred in a water bath at 50-60°C for 2-3 hours, allowed to stand for 4-5 hours, filtered, washed with deionized water, dried at 100-110°C for 8-8.5 hours, and calcined at 450-480°C for 2-2.5 hours to complete the loading of active ingredients and obtain active ingredient loaded aerogel. S103, Surface modification: The active ingredient-supported aerogel is mixed and stirred with a transition metal aqueous solution for 1.5-2 hours, then the water is evaporated in an oil bath at 80°C, and then vacuum dried at 90-100°C for 6-7 hours to obtain the first catalyst; The transition metal aqueous solution comprises a transition metal compound and deionized water. The transition metal compound comprises Co3O4, RhCl3·6H2O, and K2CrO4. The mass ratio of Co3O4, RhCl3·6H2O, K2CrO4 to deionized water is (0.2~0.5):0.1:(0.2~0.5):

100. The mass ratio of the active ingredient-loaded aerogel to the transition metal aqueous solution is 1:(8~10).

2. The concentrated solar thermal storage steam hydrogen production process as described in claim 1, characterized in that: The preparation method of Co3O4 includes the following steps: CoCl2·6H2O was dissolved in ethylene glycol and stirred until completely dissolved. Then NaOH was added, followed by polyvinylpyrrolidone K30 and oxalic acid under vigorous stirring. The mixture was reacted in an oven at 180°C for 18 h and then calcined in air at 400°C for 3 h to obtain Co3O4. The mass-to-volume ratio of CoCl2·6H2O to ethylene glycol is 1g:20mL, the molar ratio of NaOH, oxalic acid and CoCl2·6H2O is 5:1:1, and the mass of polyvinylpyrrolidone K30 added is 1 to 2 times the mass of CoCl2·6H2O.

3. The concentrated solar thermal storage steam hydrogen production process as described in claim 1, characterized in that: The preparation method of the second catalyst includes the following steps: S201. Preparation of pretreated carrier: After mixing MAB phase powder with 5wt% hydrofluoric acid solution, react at 45~50℃ for 1~2h, wash with deionized water until neutral, dry at 110~120℃ for 6~8h, compress into tablets at 20MPa, and break into 2~4mm particles to obtain pretreated carrier. S202, Active component loading: Nickel nitrate and cobalt nitrate are mixed at a molar ratio of 2:1, and then trisodium citrate, ethylene glycol, and deionized water are added and stirred to obtain a sol; the molar ratio of trisodium citrate to metal ions is 1:1, the amount of ethylene glycol and deionized water added is such that the concentration of metal ions is 0.3 mol / L, and the mass ratio of ethylene glycol to water is 1:3; The pretreated carrier is mixed with sol, ultrasonically treated for 20-30 min, dried at 75-80℃, and then calcined at 480-500℃ for 2-3 h to obtain the active ingredient loading carrier. S203, Composite Modification: Cerium oxide powder is dispersed in anhydrous ethanol at a mass ratio of 1:20, ultrasonically treated for 20-30 min, lithium stearate and manganese nitrate are added, and then the active ingredient support is added. The mixture is rotary evaporated at 48-50℃, dried at 110-120℃ for 1-2 h, and calcined at 560-600℃ for 2-3 h to obtain the second catalyst. The mass ratio of the active ingredient support carrier to cerium oxide, lithium stearate, and manganese nitrate is 2:1:0.1:0.

5.

4. The concentrated solar thermal storage steam hydrogen production process as described in claim 1, characterized in that: The first catalyst filling layer has a filling thickness of 1~5mm and an effective filling volume of 0.1~0.5 mL; The second catalyst filling layer has a filling thickness of 1~4 mm and an effective filling volume of 0.1~0.5 mL.

5. The concentrated solar thermal storage steam hydrogen production process as described in claim 1, characterized in that: The volume ratio of water vapor to inert gas is 1:(5~20), the reaction temperature of the first catalyst filling layer is 300~500℃, and the reaction temperature of the second catalyst filling layer is 300~400℃.

6. The concentrated solar thermal storage steam hydrogen production process as described in claim 1, characterized in that: In the carrier gas path, the gas flow rate is no greater than 300 NmL / min, and the pressure is 0.1~3.0 MPa.

7. The concentrated solar thermal storage steam hydrogen production process as described in claim 1, characterized in that: In the raw material injection device, the flow rate of liquid water is 0.002~5 NmL / min, and the pressure is not less than 3MPa.

Images