Application of molecular sieve as defoaming additive in hydrogen production by water electrolysis and method

Abstract

The invention provides an application and method of a molecular sieve as a defoaming additive in hydrogen production by water electrolysis, and the method for hydrogen production by water electrolysis by using the molecular sieve as the defoaming additive comprises the following steps: mixing the silicon dioxide-based molecular sieve with an electrolyte by using the silicon dioxide-based molecular sieve as the defoaming additive, and carrying out hydrogen production by water electrolysis. The silicon dioxide-based molecular sieve is used as an additive for physical defoaming, the non-conductive solid small particles can be uniformly dispersed in the electrolyte, the original water electrolysis reaction system and ion transmission are not changed, and the silicon dioxide-based molecular sieve is only used as a physical means for assisting bubble separation in the bubble evolution process; the separation radius and separation time of bubbles are greatly reduced, mass transfer overpotential of hydrogen production by water electrolysis is reduced, and contact between water in a reaction area and a catalyst is promoted, so that the energy conversion efficiency is improved, the water electrolysis potential is reduced, and the hydrogen production efficiency is improved. Moreover, the silica-based molecular sieve is controllable in size, firm in structure and low in cost, and the cost of hydrogen production by electrolysis of water can be effectively reduced.

Description

[0001] Related Applications

[0002] This application claims priority to Chinese patent application No. 2024110191070, filed on July 29, 2024, entitled “Method for producing hydrogen by electrolysis of water and hydrogen”, the entire text of which is hereby incorporated by reference. Technical Field

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

[0004] With the rapid development of renewable resources, their intermittent, random and time-space mismatching problems are becoming increasingly prominent. How to solve the problem of renewable energy consumption and ensure the safe operation of the power grid system is gradually becoming the focus of attention in the energy field. Hydrogen energy, as a large-scale and long-term energy storage method, can effectively solve the problem of renewable energy consumption. 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 to further reduce carbon emissions. Among them, water electrolysis to produce hydrogen is the most ideal way to produce hydrogen, which can achieve zero CO2 emissions. However, the high cost of water electrolysis to produce hydrogen limits the widespread application of hydrogen energy. The cost of electricity accounts for about 80% of the cost of hydrogen production. The actual voltage required for the water electrolysis reaction far exceeds the theoretical voltage, resulting in high hydrogen production costs.

[0005] Since the water electrolysis reaction involves water / gas two-phase transmission, the bubbles generated by the reaction will hinder the continuous contact between the catalyst and the electrolyte. The obstruction to the electrolysis of water in this process is also called mass transfer impedance, and the resulting overpotential is called mass transfer overpotential. In related technologies, the mass transfer impedance is often reduced by flow field, flow channel design, electrode structure, surface modification, etc. In comparison, it is simpler and cheaper to use additives to assist bubble discharge to improve mass transfer overpotential.

[0006] However, most of the current electrolytic water additives are organic reagents, which improve the catalyst and H + or OH - Bubble removal is achieved by methods such as increasing the binding energy of organic reagents. Organic reagents are not only expensive, but also have the possibility of poisoning catalysts, thereby increasing the cost of hydrogen production and reducing the efficiency of hydrogen production. Summary of the invention

[0007] Based on this, the present application provides an application and method of a molecular sieve as a defoaming additive in hydrogen production by water electrolysis, so as to reduce costs and improve hydrogen production efficiency.

[0008] The first aspect of the present application provides a method for producing hydrogen by electrolyzing water using molecular sieve as a defoaming additive, the method comprising:

[0009] A silicon dioxide-based molecular sieve is used as a defoaming additive, and the silicon dioxide-based molecular sieve is mixed with an electrolyte to electrolyze water to produce hydrogen.

[0010] In some embodiments, the particle diameter of the silica-based molecular sieve is 110nm-150nm, optionally 120nm-135nm; and / or

[0011] The particle height of the silica-based molecular sieve is 70nm-100nm, and can be optionally 75nm-85nm.

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

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

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

[0015] Tetrapropylammonium hydroxide, ethyl silicate and deionized water are mixed and subjected to hydrothermal reaction to prepare an intermediate;

[0016] The intermediate is subjected to heat treatment 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 volume ratio of tetrapropylammonium hydroxide to deionized water is (4-10) g:(10-50) mL.

[0019] In some embodiments, the temperature of the hydrothermal reaction is 130° C.-170° C., and the time is 16 h-36 h.

[0020] In some embodiments, the heat treatment is performed at a temperature of 450° C. to 650° C. and for a time of 6 h to 12 h.

[0021] A second aspect of the present application provides an application of a molecular sieve as a defoaming additive in hydrogen production by water electrolysis, 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 above-mentioned method for producing hydrogen from water electrolysis using molecular sieves as defoaming additives uses molecular sieves (which can be non-conductive molecular sieves, such as silica-based molecular sieves) as physical defoaming additives. Such non-conductive solid small particles can be evenly dispersed in the electrolyte, which will not change the original water electrolysis reaction system and ion transport, and only serve as a physical means to assist bubble detachment during the bubble evolution process, greatly reducing the bubble detachment radius and detachment time, reducing the mass transfer overpotential of water electrolysis hydrogen production, and promoting the contact between water and catalyst in the reaction area, thereby improving energy conversion efficiency, reducing water electrolysis potential, and improving hydrogen production efficiency. In addition, silica-based molecular sieves are controllable in size, sturdy in structure, and low in cost, which can effectively reduce the cost of water electrolysis hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

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

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

[0027] Figure 3 The polarization curves of electrolyzed water of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1 are shown.

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

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

[0030] For ease of understanding of the present invention, the application will be described more fully below with reference to relevant embodiments. The following provides preferred embodiments of the application. However, the application can be implemented 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 application more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0032] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or 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 "and / or", it should be understood that in the present application, the technical solution undoubtedly includes technical solutions connected by "logical and", and also undoubtedly includes technical solutions connected by "logical or".

[0033] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0034] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0035] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0036] The temperature parameters in this application, unless otherwise specified, allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0037] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0038] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0039] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0040] In the description of the application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0041] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0042] If there is no special explanation, all the steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0043] At present, most of the electrolytic water additives are organic reagents, which improve the catalyst and H by chemical means. + or OH - Bubble removal is achieved by methods such as increasing the binding energy of organic reagents. Organic reagents are not only expensive, but also have the possibility of poisoning catalysts, thereby increasing the cost of hydrogen production and reducing the efficiency of hydrogen production.

[0044] Based on the above problems, the present application adopts non-conductive molecular sieve as a physical defoaming additive, which has low cost, controllable size and strong structure. The additive can assist in expelling a large number of bubbles generated during the electrolysis of water to produce hydrogen, increase the current density of the hydrolysis reaction in the electrolyzer, 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 producing hydrogen by electrolyzing water using a molecular sieve as a defoaming additive, the method comprising: using a non-conductive molecular sieve as a defoaming additive, mixing the non-conductive molecular sieve with an electrolyte, and performing water electrolysis 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 may further be a silica-based molecular sieve.

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

[0048] One or more embodiments of the present application provide a method for producing hydrogen by electrolyzing water using molecular sieves as defoaming additives, the method comprising: using a silica-based molecular sieve as a defoaming additive, mixing the silica-based molecular sieve with an electrolyte, and performing water electrolysis to produce hydrogen.

[0049] Understandably, when hydrogen is produced by electrolysis of water, molecular sieves (which can be non-conductive molecular sieves, such as silica-based molecular sieves) are used as physical defoaming additives. Such non-conductive solid small particles can be evenly dispersed in the electrolyte, which will not change the original electrolysis reaction system and ion transport. They only serve as a physical means to assist bubble detachment during the bubble evolution process, greatly reducing the bubble detachment radius and detachment time, reducing the mass transfer overpotential of hydrogen production by electrolysis of water, and promoting the contact between water and catalyst in the reaction area, thereby improving energy conversion efficiency, reducing the electrolysis potential of water, and improving hydrogen production efficiency. In addition, silica-based molecular sieves are controllable in size, strong in structure, and low in cost, which can effectively reduce the cost of hydrogen production by electrolysis of water.

[0050] It should be noted that the use of non-conductive molecular sieves (such as silica-based molecular sieves) as defoaming additives is applicable to both alkaline solution hydrogen production and proton exchange membrane (PEM) hydrogen production.

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

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

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

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

[0055] It should be noted that, unless otherwise specified, the above-mentioned silica-based molecular sieve particles are columnar in shape, including a first surface and a second surface relative to each other, and the shapes of the first surface and the second surface are circular, elliptical or quasi-circular; the maximum size of the first surface and the second surface is defined as the particle diameter of the silica-based molecular sieve. The distance between the first surface and the second surface is defined as the particle height of the silica-based molecular sieve. When the particle diameter and particle height of the silica-based molecular sieve are respectively within the above ranges, it is beneficial to both the flow of the electrolyte and the discharge of bubbles.

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

[0057] It will be appreciated that the electrolyte referred to above and below includes water.

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

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

[0060] As a non-limiting example, a method for preparing a silica-based molecular sieve includes:

[0061] Tetrapropylammonium hydroxide, ethyl silicate and deionized water are mixed and subjected to hydrothermal reaction to prepare an intermediate; the intermediate is subjected to heat treatment to prepare a silicon dioxide-based molecular sieve.

[0062] In some embodiments, the mass ratio of tetrapropylammonium hydroxide to ethyl silicate is (4-10):(4-10); for example, it can be, but 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. Tetrapropylammonium hydroxide serves as a structure directing agent to provide a molecular sieve structure template, and ethyl silicate can provide the SiO2 raw material required for the product. When the mass ratio of tetrapropylammonium hydroxide to ethyl silicate is within the above range, it is helpful for the prepared silica-based molecular sieve to have a stable structure and sufficient pores.

[0063] As a possible embodiment, the mass volume ratio of tetrapropylammonium hydroxide to deionized water is (4-10) g:(10-50) mL; for example, it can be 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. When the amount of deionized water used is within the above range, it is beneficial to fully dissolve the reactants and provide the hydroxyl groups required for the reaction of ethyl silicate.

[0064] In some embodiments, the temperature of the hydrothermal reaction is 130°C-170°C; for example, it can be 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 above temperatures.

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

[0066] It should be noted that the temperature and time of the hydrothermal reaction can be combined in any appropriate manner, and both can be selected from any hydrothermal reaction temperature and time described in this article.

[0067] In some exemplary embodiments, the heat treatment temperature is 450°C-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 above temperatures, etc.

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

[0069] It should be noted that the temperature and time of the heat treatment can be combined in any appropriate manner, and both can be selected from any heat treatment temperature and time described in this article.

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

[0071] The following is a detailed description of the technical solution of the present application in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following embodiments are preferably 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 field, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0072] In the following specific embodiments, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0073] 1. Preparation of molecular sieves

[0074] Example 1

[0075] 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate were mixed evenly, and subjected to hydrothermal reaction at 150° C. for 24 h. The mixture was cooled, centrifuged, rinsed and dried to obtain an intermediate. The intermediate was kept at 550° C. in a muffle furnace for 8 h to obtain a 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. The details are as follows:

[0078] 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate were mixed evenly, and subjected to hydrothermal reaction at 130° C. for 36 h. The mixture was cooled, centrifuged, rinsed and dried to obtain an intermediate. The intermediate was kept at 550° C. in a muffle furnace for 8 h to obtain a molecular sieve.

[0079] Example 3

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

[0081] 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate were mixed evenly, and subjected to hydrothermal reaction at 170° C. for 16 h. The mixture was cooled, centrifuged, rinsed and dried to obtain an intermediate. The intermediate was kept at 550° C. in a muffle furnace for 8 h to obtain a molecular sieve.

[0082] Example 4

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

[0084] 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate were mixed evenly, and subjected to hydrothermal reaction at 180° C. for 72 h. The mixture was cooled, centrifuged, rinsed and dried to obtain an intermediate. The intermediate was kept at 550° C. in a muffle furnace for 8 h to obtain a molecular sieve.

[0085] Example 5

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

[0087] 4.05 g of tetrapropylammonium hydroxide, 12 mL of deionized water and 4.12 g of ethyl silicate were mixed evenly, and subjected to hydrothermal reaction at 100° C. for 24 h, followed by cooling, centrifugation, washing and drying to obtain an intermediate; the intermediate was kept at 550° C. in a muffle furnace for 8 h to obtain a molecular sieve.

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

[0089] Table 1

[0090]

[0091] 2. Application Examples

[0092] Application Example 1

[0093] Weigh 0.05 mg of the molecular sieve prepared in Example 1 and add 500 mL of electrolyte (deionized water), that is, the amount of molecular sieve added is 0.1 mg / L, ultrasonically stir evenly, and perform electrolysis water test. The process of electrolysis water test is as follows:

[0094] Based on the electrolytic water test system, turn on the circulation pump to pump the electrolyte into the electrolytic cell for circulation; finally, turn on the electrochemical workstation to set the voltage range, scan rate and other information to test the electrolytic water polarization curve; among them (the voltage range selected in this article is 1.4-2.2V, and the scan rate is 5mV / s.

[0095] Application Example 2

[0096] The difference between Application Example 2 and Application Example 1 is that the amount of molecular sieve added is different, and the other aspects are the same. The details are as follows:

[0097] 0.1 mg of the molecular sieve prepared in Example 1 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 0.2 mg / L, ultrasonically stirred evenly, and an electrolysis water test was performed. The process of the electrolysis water test was 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 amount of molecular sieve added is different, and the other aspects are the same. The details are as follows:

[0100] 0.25 mg of the molecular sieve prepared in Example 1 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 0.5 mg / L, ultrasonic stirring was performed to uniformly perform an electrolysis water test, and the process of the electrolysis water test was 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 amount of molecular sieve added is different, and the other aspects are the same. The details are as follows:

[0103] 0.5 mg of the molecular sieve prepared in Example 1 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 1.0 mg / L, ultrasonic stirring was performed to uniformly perform an electrolysis water test, and the process of the electrolysis water test was 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 amount of molecular sieve added is different, and the other aspects are the same. The details are as follows:

[0106] 0.75 mg of the molecular sieve prepared in Example 1 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of molecular sieve added was 1.5 mg / L, ultrasonic stirring was performed to uniformly perform an electrolysis water test, and the process of the electrolysis water test was the same as that of 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 other aspects are the same. The details are as follows:

[0109] 1.0 mg of the molecular sieve prepared in Example 1 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 2.0 mg / L, ultrasonically stirred evenly, and an electrolysis water test was performed. The process of the electrolysis water test was the same as that of 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 other parts are the same. The details are as follows:

[0112] 1.0 mg of the molecular sieve prepared in Example 2 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 2.0 mg / L, ultrasonically stirred evenly, and an electrolysis water test was performed. The process of the electrolysis water test was the same as that of 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 other parts are the same. The details are as follows:

[0115] 1.0 mg of the molecular sieve prepared in Example 3 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 2.0 mg / L, ultrasonically stirred evenly, and an electrolysis water test was performed. The process of the electrolysis water test was the same as that of 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 other parts are the same. The details are as follows:

[0118] 1.0 mg of the molecular sieve prepared in Example 4 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 2.0 mg / L, ultrasonically stirred evenly, and an electrolysis water test was performed. The process of the electrolysis water test was the same as that of 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 parts are the same. The details are as follows:

[0121] 1.0 mg of the molecular sieve prepared in Example 5 was weighed and added to 500 mL of electrolyte (deionized water), that is, the amount of the molecular sieve added was 2.0 mg / L, ultrasonically stirred evenly, and an electrolysis water test was performed. The process of the electrolysis water test was the same as that of Application Example 1.

[0122] Comparative application example 1

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

[0124] During the water electrolysis test, when the voltage was 2.0V, the current density test results of the above application examples and comparative application examples are shown in Table 2. The polarization curves of water electrolysis of application examples 1-6 are shown in Table 2. Figure 2 The polarization curves of electrolyzed water of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1 are shown in FIG. Figure 3 shown.

[0125] The electrolysis potential of water can be decomposed into the sum of theoretical potential, activation overpotential, ohmic overpotential and 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 When η of each of the above application examples and comparative application examples is 活化 and η 传质 The activation overpotentials of the electrolysis water polarization curves of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1 are shown in Table 2. Figure 4 The mass transfer overpotentials of the electrolysis water polarization curves of Application Example 5, Application Example 9, Application Example 10 and Comparative Application Example 1 are shown in Figure 5 shown.

[0126] Table 2

[0127]

[0128] From Table 2 and Figure 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 significantly improved, indicating that the size of the silica-based molecular sieve has a significant effect on the performance of water electrolysis. When the particle diameter of the silica-based molecular sieve is 110nm-150nm and the particle height is 70nm-100nm, the water electrolysis performance can be significantly improved. And when the voltage is 2.0V, 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 greatly improve the hydrogen production efficiency for the gas-liquid mass transfer part of water electrolysis.

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

[0130] From Table 2 and Figure 5 It can be seen that compared with comparative application example 1, after adding molecular sieve in application example 5, 2.5 A / cm 2 Time 传质 The change rate is about 25%, indicating that the addition of silica-based molecular sieves will significantly affect the mass transfer part of the water electrolysis process.

[0131] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for producing hydrogen by electrolysis of water using molecular sieve as a defoaming additive, characterized in that: The method comprises: A silicon dioxide-based molecular sieve is used as a defoaming additive, and the silicon dioxide-based molecular sieve is mixed with an electrolyte to electrolyze water to produce hydrogen.

2. The method according to claim 1, characterized in that The particle diameter of the silica-based molecular sieve is 110nm-150nm, and can be 120nm-135nm; and / or The particle height of the silica-based molecular sieve is 70nm-100nm, and can be optionally 75nm-85nm.

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

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

5. The method according to any one of claims 1 to 4, characterized in that: The preparation method of the silica-based molecular sieve comprises: Tetrapropylammonium hydroxide, ethyl silicate and deionized water are mixed and subjected to hydrothermal reaction to prepare an intermediate; The intermediate is subjected to heat treatment to prepare the silica-based molecular sieve.

6. The method according to claim 5, characterized in that The mass ratio of tetrapropylammonium hydroxide to ethyl silicate is (4-10):(4-10).

7. The method according to claim 5, characterized in that The mass volume ratio of tetrapropylammonium hydroxide and deionized water is (4-10) g:(10-50) mL.

8. The method according to claim 5, characterized in that The temperature of the hydrothermal reaction is 130° C.-170° C., and the time is 16 h-36 h.

9. The method according to claim 5, characterized in that The heat treatment temperature is 450° C.-650° C., and the time is 6 h-12 h.

10. A molecular sieve used as a defoaming additive in the electrolysis of water to produce hydrogen, characterized in that: The molecular sieve is a non-conductive molecular sieve; Optionally, the non-conductive molecular sieve comprises a silica-based molecular sieve.

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