Use of molecular sieves as a de-bubbling additive in the electrolysis of water to produce hydrogen and method

Abstract

The application provides application and method of molecular sieve as a bubble removing additive in hydrogen production by water electrolysis. The method of hydrogen production by water electrolysis using the molecular sieve as a bubble removing additive comprises using a silicon dioxide-based molecular sieve as a bubble removing additive, mixing the silicon dioxide-based molecular sieve with an electrolyte, and performing water electrolysis. The silicon dioxide-based molecular sieve is used as a physical bubble removing additive. The non-conductive solid small particles can be uniformly dispersed in the electrolyte, and the original water electrolysis reaction system and ion transmission are not changed. The silicon dioxide-based molecular sieve only serves as a physical means for assisting bubble separation in the bubble evolution process, greatly reduces the bubble separation radius and separation time, reduces the mass transfer overpotential of hydrogen production by water electrolysis, promotes the contact between the water in the reaction region and the catalyst, thereby improves the energy conversion efficiency, reduces the water electrolysis potential, and improves the hydrogen production efficiency. Moreover, the silicon dioxide-based molecular sieve has controllable size, strong structure and low cost, and can effectively reduce the cost of hydrogen production by water electrolysis.

Description

[0001] Related Applications

[0002] The present application claims priority to the Chinese patent application No. 2024110191070, filed on July 29, 2024, entitled "Method for hydrogen production by water electrolysis and hydrogen", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of hydrogen production by water electrolysis, in particular to application of molecular sieve as a bubble removal additive in hydrogen production by water electrolysis and a method. BACKGROUND

[0004] With the rapid development of renewable resources, the problems of intermittency, randomness and mismatch of load space-time are increasingly prominent, and how to solve the consumption of renewable energy and ensure the safe operation of the power grid system has gradually become the focus of the energy field. Hydrogen energy, as a large-scale long-period energy storage method, can effectively solve the consumption problem of renewable energy generation; at the same time, the application range of hydrogen energy is very wide, in addition to energy storage, it can also be used in transportation, chemical industry, metallurgy and other fields, further reducing carbon emissions. Among them, hydrogen production by water electrolysis is the most ideal hydrogen production method, which can achieve zero CO2 emission. However, the high cost of hydrogen production by water electrolysis limits the wide application of hydrogen energy, and the cost of electricity accounts for about 80% of the cost of hydrogen production, and the actual voltage required for water electrolysis reaction is much higher than the theoretical voltage, resulting in high cost of hydrogen production.

[0005] Since water electrolysis reaction involves water / gas two-phase transport, the generated gas bubbles will hinder the continuous contact of the catalyst with the electrolyte, and this process is also called mass transfer impedance, and the overpotential brought by it is called mass transfer overpotential. In related technologies, the mass transfer impedance is reduced by flow field, flow channel design, electrode structure, surface modification and other methods. Compared with this, using additives to assist bubble discharge to improve mass transfer overpotential is simpler and cheaper.

[0006] However, most of the current water electrolysis additives are organic reagents, which improve the combination energy of the catalyst with H + or OH - , etc. to achieve bubble removal. Organic reagents not only have high price, but also have the possibility of poisoning the catalyst, thereby increasing the cost of hydrogen production and reducing the efficiency of hydrogen production. SUMMARY

[0007] Therefore, the present application provides a method for using molecular sieve as a bubble removal additive in hydrogen production by water electrolysis to reduce the cost and improve the efficiency of hydrogen production.

[0008] The first aspect of the present application provides a method for hydrogen production by water electrolysis using molecular sieve as a bubble removal additive, the method comprising:

[0009] The silica-based molecular sieve is used as a defoaming additive, the silica-based molecular sieve is mixed with an electrolyte, and water is electrolyzed to produce hydrogen.

[0010] In some embodiments, the silica-based molecular sieve has a particle diameter of 110 nm-150 nm, which can be 120 nm-135 nm; and / or

[0011] The silica-based molecular sieve has a particle height of 70 nm-100 nm, which can be 75 nm-85 nm.

[0012] In some embodiments, the mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is (0.1-2) mg:1 L.

[0013] In some embodiments, the mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is (1.4-1.6) mg:1 L.

[0014] In some embodiments, the method for preparing the silica-based molecular sieve comprises:

[0015] An intermediate is prepared by mixing tetrapropylammonium hydroxide, ethyl silicate, and deionized water and then performing a hydrothermal reaction;

[0016] The intermediate is heat-treated to prepare the silica-based molecular sieve.

[0017] In some embodiments, the mass ratio of tetrapropylammonium hydroxide to ethyl silicate is (4-10):(4-10).

[0018] In some embodiments, the mass-to-volume ratio of tetrapropylammonium hydroxide to deionized water is (4-10) g:(10-50) mL.

[0019] In some embodiments, the hydrothermal reaction has a temperature of 130℃-170℃ and a time of 16 h-36 h.

[0020] In some embodiments, the heat treatment has a temperature of 450℃-650℃ and a time of 6 h-12 h.

[0021] The second aspect of the present application provides a use of a molecular sieve as a defoaming additive in the electrolysis of water to produce hydrogen, wherein the molecular sieve is a non-conductive molecular sieve.

[0022] Optionally, the non-conductive molecular sieve comprises a silica-based molecular sieve.

[0023] The method for producing hydrogen by electrolysis of water provided above uses molecular sieve (may be non-conductive molecular sieve, further such as silica-based molecular sieve) as a physical bubble removal additive. The non-conductive solid small particles can be uniformly dispersed in the electrolyte, which does not change the original electrolysis water reaction system and ion transmission, only acts as a physical means for assisting bubble detachment in the bubble evolution process, greatly reduces the bubble detachment radius and detachment time, reduces the mass transfer overpotential of electrolysis water for hydrogen production, promotes the contact of water in the reaction zone with the catalyst, thereby improving the energy conversion efficiency, reducing the electrolysis water potential, and improving the hydrogen production efficiency. In addition, the silica-based molecular sieve has controllable size, strong structure and low cost, which can effectively reduce the cost of electrolysis water for hydrogen production. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, more completely understand the present application and its beneficial effects, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0025] Figure 1 The electron scanning electron microscope images of the molecular sieves prepared in Example 1, Example 4 and Example 5.

[0026] Figure 2 The electrolysis water polarization curve graphs of Application Examples 1-6.

[0027] Figure 3 The electrolysis water polarization curve graphs of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1.

[0028] Figure 4 The activation overpotential of the electrolysis water polarization curve of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1.

[0029] Figure 5 The mass transfer overpotential of the electrolysis water polarization curve of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to relevant embodiments. The following gives the preferred embodiments of the present application. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0032] The selection scope of the terms "and / or", "or / and", "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", "and / or", it should be understood that in this application, the technical solution undoubtedly includes the technical solution connected by "logical and", and also undoubtedly includes the technical solution connected by "logical or".

[0033] In this application, in the technical features described in an open manner, both the closed technical solution consisting of the listed features and the open technical solution containing the listed features are included.

[0034] In this application, when referring to a numerical interval, unless otherwise specified, the numerical interval is considered to be continuous and includes the minimum value and the maximum value of the range, as well as every value between the minimum value and the maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges encompassed therein.

[0035] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each individual disclosed point or single numerical value can itself be combined as a lower limit or an upper limit with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recited.

[0036] In this application, the temperature parameter, unless otherwise specified, allows for constant temperature treatment, and also allows for treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuation within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C is allowed.

[0037] In the present application, the "suitable" in "suitable combination", "suitable manner", "any suitable manner" and the like is subject to the ability to implement the technical solutions of the present application, solve the technical problems of the present application, and achieve the intended technical effects of the present application.

[0038] In the present application, "further", "still further", "in particular" and the like are used for the purpose of description, indicating differences in content, but should not be understood as limiting the scope of protection of the present application.

[0039] In the present application, "optionally", "optional" and "optional" mean optional, i.e. selected from either of the two parallel schemes "with" or "without". If there are multiple "options" in a technical solution, unless otherwise specified, and there is no contradictory relationship or mutual restriction, each "option" is independent.

[0040] In the description of the application, "multiple" means at least two, for example, two, three, etc., unless otherwise specifically limited.

[0041] If not specifically stated, all embodiments and optional embodiments of the present application can be combined to form new technical solutions. If not specifically stated, all technical features and optional technical features of the present application can be combined to form new technical solutions.

[0042] If not specifically stated, all steps of the present application can be performed in sequence or randomly, preferably in sequence.

[0043] Most of the current water electrolysis additives are organic reagents, which improve the combination of catalyst and H + or OH - by chemical means, such as bubble removal, organic reagents not only have high price, but also have the possibility of poisoning the catalyst, thereby increasing the cost of hydrogen production and reducing the efficiency of hydrogen production.

[0044] Based on the above problems, the present application uses non-conductive molecular sieve as a physical bubble removal additive, which is low in cost, controllable in size, and strong in structure. The additive can assist in discharging a large amount of bubbles generated during the electrolysis of water to produce hydrogen, improve the water splitting reaction current density of the electrolytic cell, reduce the mass transfer overpotential, and improve the efficiency of water electrolysis.

[0045] One or more embodiments of the present application provide a method for electrolysis of water to produce hydrogen using molecular sieve as a bubble removal additive, the method comprising: using non-conductive molecular sieve as a bubble removal additive, mixing the non-conductive molecular sieve with the electrolyte, and performing electrolysis of water to produce hydrogen.

[0046] Based on any suitable embodiment of the present application, in some embodiments, the non-conductive molecular sieve includes a silica-based molecular sieve, and can further be a silica-based molecular sieve.

[0047] In some embodiments, the silica-based molecular sieve is a silica molecular sieve, based on any suitable embodiment of the present application.

[0048] One or more embodiments of the present application provide a method of hydrogen production by water electrolysis using a molecular sieve as a bubble removal additive, the method comprising: using a silica-based molecular sieve as a bubble removal additive, mixing the silica-based molecular sieve with an electrolyte, and performing hydrogen production by water electrolysis.

[0049] Understandably, a molecular sieve (which can be a non-conductive molecular sieve, further such as a silica-based molecular sieve) is used as a physical bubble removal additive during hydrogen production by water electrolysis. Such non-conductive solid small particles can be uniformly dispersed in the electrolyte, which does not change the original water electrolysis reaction system and ion transmission. Only in the process of bubble evolution, it serves as a physical means to assist bubble detachment, greatly reduces the bubble detachment radius and detachment time, reduces the mass transfer overpotential of hydrogen production by water electrolysis, promotes the contact between the water in the reaction zone and the catalyst, thereby improving the energy conversion efficiency, reducing the water electrolysis potential, and improving the hydrogen production efficiency. In addition, the silica-based molecular sieve has controllable size, strong structure, and low cost, which can effectively reduce the cost of hydrogen production by water electrolysis.

[0050] It should be noted that the non-conductive molecular sieve (such as a silica-based molecular sieve) is used as a bubble removal additive, which is applicable to both alkaline hydrogen production and proton exchange membrane (PEM) hydrogen production.

[0051] As a non-limiting example, the hydrogen production system by electrolysis includes an electrolytic cell, an electrochemical workstation (for example, model: CHI750E), an electrolyte (deionized water), and a circulating pump. The method of hydrogen production by water electrolysis includes the following steps: first, adding a non-conductive molecular sieve (such as a silica-based molecular sieve) into the electrolyte and uniformly dispersing it; then, turning on the circulating pump to pump the electrolyte into the electrolytic cell to realize circulation; finally, turning on the power supply to supply power to the electrolytic cell to produce hydrogen.

[0052] In some optional embodiments, the silica-based molecular sieve is a silica molecular sieve.

[0053] In some embodiments, the silica-based molecular sieve has a particle diameter of 110 nm to 150 nm; for example, but not limited to, 110 nm, 111 nm, 112 nm, 113 nm, 114 nm, 115 nm, 116 nm, 117 nm, 118 nm, 119 nm, 120 nm, 121 nm, 122 nm, 123 nm, 124 nm, 125 nm, 126 nm, 127 nm, 128 nm, 129 nm, 130 nm, 131 nm, 132 nm, 133 nm, 134 nm, 135 nm, 136 nm, 137 nm, 138 nm, 139 nm, 140 nm, 141 nm, 142 nm, 143 nm, 144 nm, 145 nm, 146 nm, 147 nm, 148 nm, 149 nm, 150 nm, or a range between any two of the foregoing values, etc. Alternatively, the silica-based molecular sieve has a particle diameter of 120 nm to 135 nm.

[0054] As one possible embodiment, the silica-based molecular sieve has a particle diameter of 70 nm to 100 nm; for example, but not limited to, 70 nm, 71 nm, 72 nm, 73 nm, 74 nm, 75 nm, 76 nm, 77 nm, 78 nm, 79 nm, 80 nm, 81 nm, 82 nm, 83 nm, 84 nm, 85 nm, 86 nm, 87 nm, 88 nm, 89 nm, 90 nm, 91 nm, 92 nm, 93 nm, 94 nm, 95 nm, 96 nm, 97 nm, 98 nm, 98 nm, 100 nm, or a range between any two of the foregoing values, etc. Alternatively, the silica-based molecular sieve has a particle diameter of 75 nm to 85 nm.

[0055] It is noted that, unless otherwise specified, the silica-based molecular sieve particles mentioned above have a columnar shape, including opposite first and second surfaces, the first and second surfaces have a circular, elliptical, or quasi-circular shape; the largest dimension of the first and second surfaces defines the particle diameter of the silica-based molecular sieve. The distance between the first and second surfaces defines the particle height of the silica-based molecular sieve. When the particle diameter and the particle height of the silica-based molecular sieve are within the ranges described above, both the electrolyte flow and the bubble discharge are facilitated.

[0056] In some embodiments, the mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is (0.1-2) mg: 1 L; for example, it can be, but is not limited to, 0.1 mg: 1 L, 0.2 mg: 1 L, 0.3 mg: 1 L, 0.4 mg: 1 L, 0.5 mg: 1 L, 0.6 mg: 1 L, 0.7 mg: 1 L, 0.8 mg: 1 L, 0.9 mg: 1 L, 1 mg: 1 L, 1.1 mg: 1 L, 1.2 mg: 1 L, 1.3 mg: 1 L, 1.4 mg: 1 L, 1.5 mg: 1 L, 1.6 mg: 1 L, 1.7 mg: 1 L, 1.8 mg: 1 L, 1.9 mg: 1 L, 2 mg: 1 L, or a range between any two of the above mass-to-volume ratios. When the mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is within the above range, a certain amount of the molecular sieve solid in the electrolyte can be ensured, thereby ensuring the bubble removal effect, and at the same time, the excessive amount of the molecular sieve sample can be prevented from blocking the diffusion layer, the membrane, and even the accessory system components.

[0057] It can be understood that the electrolyte mentioned in the context includes water.

[0058] In some alternative embodiments, the mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is (1.4-1.6) mg: 1 L.

[0059] In some alternative embodiments, the mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is 1.5 mg: 1 L.

[0060] As a non-limiting example, the preparation method of the silica-based molecular sieve includes:

[0061] The intermediate is prepared by mixing tetrapropylammonium hydroxide, ethyl silicate, and deionized water and then performing a hydrothermal reaction; and the silica-based molecular sieve is prepared by heat treating the intermediate.

[0062] In some embodiments, the mass ratio of the tetrapropylammonium hydroxide to the ethyl silicate is (4-10):(4-10); for example, it can be, but is not limited to, (4-9):(4-9), (4-8):(4-8), (4-7):(4-7), (4-6):(4-6), (4-5):(4-10), (4-5):(4-5), (5-10):(5-10), (6-10):(6-10), (7-10):(7-10), (8-10):(8-10), or (9-10):(9-10), etc. The tetrapropylammonium hydroxide serves as a structure directing agent to provide a molecular sieve structure template, and the ethyl silicate can provide the required SiO2 raw material for the product. When the mass ratio of the tetrapropylammonium hydroxide to the ethyl silicate is within the above range, it is helpful to prepare a silica-based molecular sieve with stable structure and sufficient porosity.

[0063] As one possible embodiment, the mass to volume ratio of tetrapropylammonium hydroxide and deionized water is (4-10) g:(10-50) mL; for example, but not limited to, (4-9.5) g:(10-47) mL, (4-9) g:(10-45) mL, (4-8.5) g:(10-43) mL, (4-8) g:(10-40) mL, (4-7.5) g:(10-37) mL, (4-7) g:(10-35) mL, (4-6.5) g:(10-30) mL, (4-6) g:(10-25) mL, (4-5.5) g:(10-20) mL, (4-5) g:(10-15) mL, (4.5-10) g:(15-50) mL, (5-10) g:(18-50) mL, (5.5-10) g:(20-50) mL, (6-10) g:(23-50) mL, (6.5-10) g:(25-50) mL, (7-10) g:(28-50) mL, (7.5-10) g:(30-50) mL, (8-10) g:(35-50) mL, (8.5-10) g:(40-50) mL, or (9-10) g:(45-50) mL, etc. The amount of deionized water is used to facilitate the dissolution of the reactants and to provide the hydroxyl groups needed for the ethyl silicate reaction when the amount is within the above range.

[0064] In some embodiments, the temperature of the hydrothermal reaction is 130 °C to 170 °C; for example, but not limited to, 130 °C, 132 °C, 134 °C, 136 °C, 138 °C, 140 °C, 142 °C, 144 °C, 146 °C, 148 °C, 150 °C, 152 °C, 154 °C, 156 °C, 158 °C, 160 °C, 162 °C, 164 °C, 166 °C, 168 °C, 170 °C, or a range between any two of the foregoing, etc.

[0065] In some exemplary embodiments, the time of the hydrothermal reaction is 16 h to 36 h; for example, but not limited to, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h, 28 h, 29 h, 30 h, 31 h, 32 h, 33 h, 34 h, 35 h, 36 h, or a range between any two of the foregoing, etc.

[0066] It is to be understood that the temperature and time of the hydrothermal reaction can be combined in any suitable manner, and each can be selected from any of the temperatures and times of the hydrothermal reaction described herein.

[0067] In some exemplary embodiments, the temperature of the heat treatment is 450-650°C; for example, it can be but is not limited to 450°C, 470°C, 490°C, 500°C, 520°C, 540°C, 560°C, 580°C, 600°C, 620°C, 640°C, 650°C, or a range between any two of the aforementioned temperatures, etc.

[0068] As one possible embodiment, the time of the heat treatment is 6-12h; for example, it can be but is not limited to 6h, 7h, 8h, 9h, 10h, 11h, 12h, or a range between any two of the aforementioned times, etc.

[0069] It should be noted that the temperature and time of the heat treatment can be combined in any suitable manner, and both can be selected from any of the temperatures and times of the heat treatment described herein.

[0070] One or more embodiments of the present application provide an application of a molecular sieve as a defoaming additive in hydrogen production by electrolysis of water, wherein the molecular sieve is an electrically non-conductive molecular sieve. The definition of the electrically non-conductive molecular sieve can be referred to the definition in the context.

[0071] The technical solutions of the present application are described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and are not used to limit the scope of the present application. If the specific conditions are not specified in the following examples, the experimental methods are preferred to be referred to the guidance given in the present application, and can also be carried out according to the experimental manual or conventional conditions in the art, or according to the conditions suggested by the manufacturer, or by referring to the experimental methods known in the art.

[0072] In the following specific embodiments, the measurement parameters of the raw material components may, without specific instructions, have slight deviations within the weighing accuracy range. The temperature and time parameters allow for acceptable deviations caused by instrument testing accuracy or operation accuracy.

[0073] I. Preparation of molecular sieve

[0074] Example 1

[0075] 4.05g of tetrapropylammonium hydroxide, 12mL of deionized water and 4.12g of ethyl silicate were mixed uniformly and hydrothermally reacted at 150°C for 24h, and then cooled, centrifuged, washed and dried to obtain an intermediate; the intermediate was kept in a muffle furnace at 550°C for 8h to obtain the molecular sieve.

[0076] Example 2

[0077] The difference between the preparation method of Example 2 and the preparation method of Example 1 is that the temperature and time of the hydrothermal reaction are different. Specifically as follows:

[0078] Mix 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate uniformly, and hydrothermally react at 130℃ for 36 h, cool, centrifuge, rinse, dry to obtain an intermediate; heat the intermediate in a muffle furnace at 550℃ for 8 h to obtain the molecular sieve.

[0079] Example 3

[0080] The difference between the preparation method of Example 3 and the preparation method of Example 1 is the temperature and time of the hydrothermal reaction. Details are as follows:

[0081] Mix 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate uniformly, and hydrothermally react at 170℃ for 16 h, cool, centrifuge, rinse, dry to obtain an intermediate; heat the intermediate in a muffle furnace at 550℃ for 8 h to obtain the molecular sieve.

[0082] Example 4

[0083] The difference between the preparation method of Example 4 and the preparation method of Example 1 is the temperature and time of the hydrothermal reaction. Details are as follows:

[0084] Mix 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate uniformly, and hydrothermally react at 180℃ for 72 h, cool, centrifuge, rinse, dry to obtain an intermediate; heat the intermediate in a muffle furnace at 550℃ for 8 h to obtain the molecular sieve.

[0085] Example 5

[0086] The difference between the preparation method of Example 5 and the preparation method of Example 1 is the temperature and time of the hydrothermal reaction. Details are as follows:

[0087] Mix 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate uniformly, and hydrothermally react at 100℃ for 24 h, cool, centrifuge, rinse, dry to obtain an intermediate; heat the intermediate in a muffle furnace at 550℃ for 8 h to obtain the molecular sieve.

[0088] The particle diameter and height of the molecular sieves prepared in Examples 1-5 were tested by scanning electron microscopy, and the results are shown in Table 1. The scanning electron microscope images of the molecular sieves prepared in Example 1, Example 4 and Example 5 are shown in Figure 1

[0089] Table 1

[0090]

[0091] II. Application Examples

[0092] Application Example 1 ​

[0093] Take 0.05 mg of the molecular sieve prepared in Example 1 into 500 mL of electrolyte (deionized water), i.e. the addition amount of the molecular sieve is 0.1 mg / L, ultrasonic stirring is uniform, electrolytic water test is carried out, and the process of electrolytic water test is as follows:

[0094] Based on the electrolytic water test system, the circulating pump is started to pump the electrolyte into the electrolytic tank to realize circulation; finally, the electrochemical workstation is started to set the voltage range, scan speed and other information, and the electrolytic water polarization curve is tested; wherein (in this paper, the voltage range is 1.4-2.2 V, and the scan speed is 5 mV / s.

[0095] Application Example 2

[0096] The difference between Application Example 2 and Application Example 1 is that the addition amount of the molecular sieve is different, and the others are the same. Specifically as follows:

[0097] Take 0.1 mg of the molecular sieve prepared in Example 1 into 500 mL of electrolyte (deionized water), i.e. the addition amount of the molecular sieve is 0.2 mg / L, ultrasonic stirring is uniform, electrolytic water test is carried out, and the process of electrolytic water test is the same as that of Application Example 1.

[0098] Application Example 3

[0099] The difference between Application Example 3 and Application Example 1 is that the addition amount of the molecular sieve is different, and the others are the same. Specifically as follows:

[0100] Take 0.25 mg of the molecular sieve prepared in Example 1 into 500 mL of electrolyte (deionized water), i.e. the addition amount of the molecular sieve is 0.5 mg / L, ultrasonic stirring is uniform, electrolytic water test is carried out, and the process of electrolytic water test is the same as that of Application Example 1.

[0101] Application Example 4

[0102] The difference between Application Example 4 and Application Example 1 is that the addition amount of the molecular sieve is different, and the others are the same. Specifically as follows:

[0103] Take 0.5 mg of the molecular sieve prepared in Example 1 into 500 mL of electrolyte (deionized water), i.e. the addition amount of the molecular sieve is 1.0 mg / L, ultrasonic stirring is uniform, electrolytic water test is carried out, and the process of electrolytic water test is the same as that of Application Example 1.

[0104] Application Example 5

[0105] The difference between Application Example 5 and Application Example 1 is that the addition amount of the molecular sieve is different, and the others are the same. Specifically as follows:

[0106] Take 0.75 mg of the molecular sieve prepared in Example 1 and add it to 500 mL of electrolyte (deionized water), i.e. the amount of molecular sieve added is 1.5 mg / L, and then uniformly stir it by ultrasonic agitation, and then perform electrolytic water testing, and the process of electrolytic water testing is the same as in Application Example 1.

[0107] Application Example 6

[0108] The difference between Application Example 6 and Application Example 1 is that the amount of molecular sieve added is different, and the others are the same. The details are as follows:

[0109] Take 1.0 mg of the molecular sieve prepared in Example 1 and add it to 500 mL of electrolyte (deionized water), i.e. the amount of molecular sieve added is 2.0 mg / L, and then uniformly stir it by ultrasonic agitation, and then perform electrolytic water testing, and the process of electrolytic water testing is the same as in Application Example 1.

[0110] Application Example 7

[0111] The difference between Application Example 7 and Application Example 5 is that the same amount of molecular sieve prepared in Example 2 is used, and the others are the same. The details are as follows:

[0112] Take 1.0 mg of the molecular sieve prepared in Example 2 and add it to 500 mL of electrolyte (deionized water), i.e. the amount of molecular sieve added is 2.0 mg / L, and then uniformly stir it by ultrasonic agitation, and then perform electrolytic water testing, and the process of electrolytic water testing is the same as in Application Example 1.

[0113] Application Example 8

[0114] The difference between Application Example 8 and Application Example 5 is that the same amount of molecular sieve prepared in Example 3 is used, and the others are the same. The details are as follows:

[0115] Take 1.0 mg of the molecular sieve prepared in Example 3 and add it to 500 mL of electrolyte (deionized water), i.e. the amount of molecular sieve added is 2.0 mg / L, and then uniformly stir it by ultrasonic agitation, and then perform electrolytic water testing, and the process of electrolytic water testing is the same as in Application Example 1.

[0116] Application Example 9

[0117] The difference between Application Example 9 and Application Example 5 is that the same amount of molecular sieve prepared in Example 4 is used, and the others are the same. The details are as follows:

[0118] Take 1.0 mg of the molecular sieve prepared in Example 4 and add it to 500 mL of electrolyte (deionized water), i.e. the amount of molecular sieve added is 2.0 mg / L, and then uniformly stir it by ultrasonic agitation, and then perform electrolytic water testing, and the process of electrolytic water testing is the same as in Application Example 1.

[0119] Application Example 10

[0120] The difference between Application Example 10 and Application Example 5 is that the same amount of molecular sieve prepared in Example 5 is used, and the other conditions are the same. The specific conditions are as follows.

[0121] 1.0 mg of the molecular sieve prepared in Example 5 is weighed and added to 500 mL of electrolyte (deionized water), that is, the addition amount of the molecular sieve is 2.0 mg / L, and the electrolytic water test is carried out after ultrasonic stirring. The electrolytic water test process is the same as that of Application Example 1.

[0122] Comparative Application Example 1

[0123] Without adding the molecular sieve, 500 mL of electrolyte (deionized water) is directly used, and the same ultrasonic stirring operation as in Application Example 1 is used to carry out the electrolytic water test. The electrolytic water test process is the same as that of Application Example 1.

[0124] In the electrolytic water test process, when the voltage is 2.0 V, the current density test results of the above application examples and the comparative application example are shown in Table 2. The electrolytic water polarization curve of Application Examples 1-6 is shown in Figure 2 . The electrolytic water polarization curve of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1 is shown in Figure 3 .

[0125] The electrolytic water potential can be decomposed into the sum of the theoretical potential, the activation overpotential, the ohmic overpotential and the mass transfer overpotential, V 总 = V 理论 + η 活化 + η 欧姆 + η 传质 When the current density is 2.5 A / cm 2 , the η 活化 and η 传质 of the above application examples and the comparative application example are shown in Table 2, respectively. The activation overpotential of the electrolytic water polarization curve of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1 is shown in Figure 4 . The mass transfer overpotential of the electrolytic water polarization curve of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1 is shown in Figure 5 .

[0126] Table 2

[0127]

[0128] From Table 2 and Figures 2-3It can be seen that compared with application examples 9-10 and comparative application example 1, the current density of application example 5 is obviously improved, indicating that the size of the silica-based molecular sieve has a significant effect on the water electrolysis performance, and when the particle diameter of the silica-based molecular sieve is 110 nm-150 nm and the particle height is 70 nm-100 nm, the water electrolysis performance can be significantly improved. And at a voltage of 2.0 V, compared with comparative application example 1, the current density of application example 5 is increased by 16%, indicating that the silica-based molecular sieve can be used for the gas-liquid mass transfer part of water electrolysis, and can greatly improve the hydrogen production efficiency.

[0129] It can be seen from Table 2 and Figure 4 Compared with comparative application example 1, the change of η at 2.5 A / cm 2 活化 of application example 5 after adding the molecular sieve is only 8 mV (<5%), indicating that adding the silica-based molecular sieve does not affect the activation part of the water electrolysis process.

[0130] It can be seen from Table 2 and Figure 5 Compared with comparative application example 1, the change of η at 2.5 A / cm 2 传质 of application example 5 after adding the molecular sieve is about 25%, indicating that adding the silica-based molecular sieve greatly affects the mass transfer part of the water electrolysis process.

[0131] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0132] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, some modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.​​

Claims

1. A method for producing hydrogen by electrolysis of water using a molecular sieve as a defoaming additive, characterized by, The method includes: A silica-based molecular sieve is used as a defoaming additive. The silica-based molecular sieve is mixed with an electrolyte to produce hydrogen by electrolysis of water. The method for preparing the silica-based molecular sieve includes: mixing tetrapropylammonium hydroxide, ethyl silicate and deionized water and then carrying out a hydrothermal reaction to prepare an intermediate; and subjecting the intermediate to heat treatment to prepare the silica-based molecular sieve.

2. The method of claim 1, wherein, The silica-based molecular sieve has a particle diameter of 110 nm-150 nm; and / or The particle height of the silica-based molecular sieve is 70nm-100nm.

3. The method as described in claim 2, characterized in that, The silica-based molecular sieve has a particle diameter of 120nm-135nm.

4. The method as described in claim 2, characterized in that, The particle height of the silica-based molecular sieve is 75nm-85nm.

5. The method as described in claim 1, characterized in that, The mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is (0.1-2) mg:1 L.

6. The method as described in claim 1, characterized in that, The mass-to-volume ratio of the silica-based molecular sieve to the electrolyte is (1.4-1.6) mg:1 L.

7. The method as described in claim 1, characterized in that, The mass ratio of tetrapropylammonium hydroxide to ethyl silicate is (4-10):(4-10).

8. The method as described in claim 1, characterized in that, The mass-to-volume ratio of tetrapropylammonium hydroxide to deionized water is (4-10) g:(10-50) mL.

9. The method as described in claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 130℃-170℃ for a duration of 16h-36h.

10. The method as described in claim 1, characterized in that, The heat treatment temperature is 450℃-650℃, and the time is 6h-12h.

11. The application of a molecular sieve as an antifoaming additive in hydrogen production by water electrolysis, characterized in that, The molecular sieve is a non-conductive molecular sieve; the non-conductive molecular sieve includes silica-based molecular sieves. The method for preparing the silica-based molecular sieve includes: mixing tetrapropylammonium hydroxide, ethyl silicate and deionized water and then carrying out a hydrothermal reaction to prepare an intermediate; and subjecting the intermediate to heat treatment to prepare the silica-based molecular sieve.

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