CN101191237A - A preparation method of an integrated electrode for hydrogen production and storage - Google Patents

Abstract

The invention relates to a hydrogen making, hydrogen storing combination electrode method of preparation which is applied to electrolyzed water hydrogen making and organic electrocatalysis hydrogen storing technologies. In the invention, the electrocatalyst silver amalgam is plated on the ion exchange membrane based on the multiple step chemical method and combined with the ion exchange membrane, forming a composite electrode, wherein the multiple step chemical method is that the ion exchange membrane is plated with the silver based on the impregnation reduction method and combined with the silver based on the chemical deposit method or the impregnation reduction method, forming the silver amalgam. The process of the electrolyzed water hydrogen making and the organic hydrogenation storing, in which the electrode of the invention is adopted, makes use of mild conditions under which the silver and the mercury are alloyed, the hydrogen overvoltage of the mercury is relatively high, thereby well restricting the hydrogen evolution and improving the reaction velocity, along with easy preparation; moreover, the current efficiency of the alloy electrode prepared based on the method of the invention reaches 30 to 40 percent and is obviously improved.

Description

A preparation method of an integrated electrode for hydrogen production and storage

technical field

The invention relates to a preparation method of an integrated electrode for hydrogen production and hydrogen storage, which can be applied in the technologies of hydrogen production by electrolysis of water and electrocatalytic hydrogen storage of organic matter.

Background technique

Hydrogen energy is considered to be the most potential, pollution-free and environmentally friendly green energy in the new century because of its cleanness, high efficiency and abundance. Various researches on the development and utilization of hydrogen energy have been valued by the industry. The development and utilization of hydrogen energy is based on the storage of hydrogen energy. Combining water electrolysis hydrogen production and organic matter electrocatalytic hydrogen storage as a whole, using ion exchange membrane electrodes through electrochemical process, in the electrochemical process, the electrolysis reaction of water occurs at the anode, so that the protons produced by water electrolysis are in the cathode and unsaturated Organic matter undergoes electrochemical hydrogenation reaction to realize hydrogen storage.

Patent application 200410033882.8 discloses a method that uses electrolysis of water as the anode, conducts electrocatalytic hydrogenation of organic matter at the cathode, "loads" hydrogen on the organic matter, and uses ion-exchange membrane electrodes to make the protons generated by water electrolysis be in situ on the cathode Utilization, thus using "quasi-in-situ" synthesis technology to combine hydrogen production and hydrogen storage. Ion-exchange membrane is a kind of organic high polymer that can efficiently transfer protons. Its ability to transfer protons (its ion conductance is similar to that of dilute sulfuric acid solution) is strong. In ion-exchange membrane electrodes, the transfer of protons between the anode and the cathode depends on ions. Membranes, therefore, are beneficial for reducing the charge transport resistance for electrolysis in non-aqueous media.

The electrode commonly used in the above hydrogen production and hydrogen storage coupling technology is a composite electrode combined with an organic hydrogenation electrocatalyst and an ion exchange membrane. The electrode selectivity and current efficiency need to be further improved. In order to suppress hydrogen evolution, increase the speed of the main reaction, and improve The current efficiency needs to be improved.

Contents of the invention

The purpose of the present invention is to provide a hydrogen production and hydrogen storage integrated electrode preparation method that suppresses hydrogen evolution, increases the speed of the main reaction, and improves the current efficiency.

The present invention adopts following technical scheme to realize:

The electrocatalyst silver amalgam is plated on the ion exchange membrane by a step-by-step chemical method, and combined with the ion exchange membrane to form a composite electrode.

Wherein the step-by-step chemical method refers to first plating silver on the ion exchange membrane by dipping reduction method, and then adopting chemical deposition method or dipping reduction method to form silver amalgam.

The present invention also adopts following technical solutions to realize:

Among them, the conditions for silver plating on the ion exchange membrane by the immersion reduction method are [Ag(NH ₃ ) ₂ ] ⁺ concentration 0.002-0.02mol/L, immersion temperature 50-90℃, immersion time 30-60 minutes, formaldehyde concentration 0.1-2 %, the reduction temperature is 50-90°C, and the reduction time is 5-120 minutes.

The conditions for forming amalgam by dipping reduction method are _HgCl2 concentration 0.002-0.02mol/L, dipping temperature 30-90°C, dipping time 30-90 minutes, _SnCl2 concentration 0.1-6%, reduction temperature 20-90°C, The reduction time is 5-120 minutes.

The conditions for forming silver amalgam by chemical deposition method are HgCl ₂ concentration 0.005-0.02mol/L, SnCl ₂ concentration 1-6%, reaction temperature 20-90°C, and reaction time 2-6 hours.

The electrode of the present invention is used in the process of hydrogen production by electrolysis of water-hydrogenation and storage of organic matter, which utilizes amalgam to form an alloy with mild conditions, and the hydrogen overpotential of mercury is relatively high, which can well inhibit hydrogen evolution, increase the speed of the main reaction, and facilitate Preparation, the current efficiency of the alloy electrode prepared by the invention can reach 35-40%, and the current efficiency is obviously improved.

Detailed ways

The preparation method of the electrode used in the present invention is a step-by-step method for preparing alloy electrodes. Firstly, the ion-exchange membrane is plated with silver by the dipping reduction method, and then the silver amalgam is formed by the chemical deposition method or the dipping reduction method.

The silver-plating process on the ion-exchange membrane by the immersion reduction method is as follows: prepare a certain concentration of silver ammonium complex salt solution and a certain concentration of formaldehyde solution; assemble the selected ion membrane in the reactor, put the preheated silver ammonium Add the complex salt solution into the reactor to impregnate the metal complex salt oxidant on the surface of the membrane at a constant temperature; after the impregnation, pour out the solution, rinse the inner surface of the reactor with deionized water, and then pour the preheated formaldehyde solution into the reaction After the reduction time is over, the membrane is taken out from the reactor to be cleaned, dried, weighed and stored in sequence.

The technical parameters for preparing the electrode by the impregnation reduction method are preferably: [Ag(NH ₃ ) ₂ ] ⁺ concentration 0.002-0.02mol/L, immersion temperature 50-90°C, immersion time 30-60 minutes, formaldehyde concentration 0.1-2%, The reduction temperature is 50-90°C, and the reduction time is 5-120 minutes. .

The chemical deposition method silver amalgam process is mainly as follows: prepare the silver-plated ion exchange membrane, prepare a certain concentration of metal salt solution and reducing agent solution and preheat to the reaction temperature; carry out the chemical deposition reaction at a certain reaction temperature, and the reaction time is over Finally, take out the membrane electrode and clean it with an ultrasonic cleaner (generally about 5min); the reaction conditions are preferably: HgCl _{Concentration} 0.005-0.02mol/L, _SnCl Concentration 1-6%, reaction temperature 20-90°C, reaction Time 2-6 hours.

The process of preparing the electrode by impregnation reduction method is: prepare a certain concentration of metal complex salt solution and a certain concentration of NaBH ₄ solution; assemble the selected ion membrane in the reactor, add the preheated metal complex salt solution to the In the reactor, the metal complex salt oxidant is impregnated on the surface of the membrane at a constant temperature; after the impregnation, pour out the solution, rinse the inner surface of the reactor with deionized water, and then pour the preheated NaBH ₄ solution into the reactor for reduction; After the reduction time is over, the membrane is taken out from the reactor to be washed, dried, weighed and stored in sequence.

The technical parameters for preparing silver amalgam electrodes by impregnation reduction method are preferably: _HgCl2 concentration 0.002-0.02mol/L, immersion temperature 30-90°C, immersion time 30-90 minutes, _SnCl2 concentration 0.1-6%, reduction temperature 20 -90°C, reduction time 5-120 minutes.

The present invention also provides the following specific examples.

The unsaturated organic compound that is used for hydrogenation reaction in the example is benzene, and the condition of this gas-liquid reaction is:

The temperature of the benzene storage tank is 20-90°C;

The temperature of the water storage tank is 20-90°C;

Electrolysis temperature 20-90℃;

The carrier gas flow rate of benzene is 40-100ml/min, and the carrier gas flow rate of water is 40-100ml/min;

Electrolytic test medium: sulfuric acid solution with a concentration of 0.005-1mol/l;

Reference electrode: saturated calomel electrode;

Example 1:

Plating silver on the ion exchange membrane by immersion reduction method: prepare the silver ammonium complex salt solution [Ag(NH ₃ ) ₂ ] ⁺ concentration 0.01mol/L, and 1% formaldehyde solution; assemble the weighed Nafion membrane on In the reactor, add the preheated metal complex salt solution into the reactor, control the temperature at 60°C, and impregnate with ultrasonic constant temperature for about 40 minutes, so that the metal complex salt oxidant is impregnated on the surface of the membrane; after the impregnation, pour out the solution, After slightly rinsing the inner surface of the reactor with deionized water, pour the formaldehyde solution preheated to 60°C into the reactor for reduction. The reduction reaction time is 1.0 hour; Weigh and save.

Preparation of silver amalgam by chemical deposition method: Prepare the silver-plated ion exchange membrane, configure a certain concentration of metal salt solution and reducing agent solution and preheat to the reaction temperature; carry out chemical deposition reaction at a certain reaction temperature, after the reaction time is over , take out the membrane electrode and clean it with an ultrasonic cleaner (generally about 5 minutes); the reaction conditions are preferably: HgCl ₂ concentration 0.01mol/L, SnCl ₂ concentration 4%, reaction temperature 50°C, reaction time 3 hours.

The silver amalgam electrode obtained by the above method uses a gas/liquid phase benzene hydrogenation-water electrolysis reaction device for electrochemical reaction, the electrolysis temperature and humidified water vapor in the reaction are 70 ° C, and the reference electrode is a saturated calomel electrode; electrolysis test Medium: The cathode is benzene vapor, which is carried by nitrogen gas into the cathode from the air inlet at a flow rate of 60ml/min; the anode chamber is 0.5mol/L sulfuric acid.

The reaction product is analyzed by chromatography, and cyclohexane and cyclohexene, the products of hydrogenation of benzene, can be obtained, and hydrogen is also present as a by-product, and the current efficiency reaches 35%.

Example 2:

Adopt the same dipping reduction method as in Example 1 to plate silver on the ion-exchange membrane: the extraction conditions are: silver ammonium complex salt solution [Ag(NH ₃ ) ₂ ] ⁺ concentration 0.015mol/L, 0.8% formaldehyde solution; The temperature of the device is controlled at 50°C, ultrasonic constant temperature impregnation is about 40 minutes, and the formaldehyde solution preheated to 50°C is poured into the reactor for reduction, and the reduction reaction time is 0.5 hours.

Preparation of silver amalgam electrode by impregnation reduction method: Prepare a certain concentration of HgCl ₂ solution and SnCl ₂ solution; assemble the selected ion membrane in the reactor, add the preheated HgCl ₂ solution into the reactor, and keep the temperature constant Impregnation; after impregnation, pour out the solution, rinse the inner surface of the reactor with deionized water, pour the preheated SnCl ₂ solution into the reactor for reduction; after the reduction time is over, take out the membrane from the reactor and proceed Wash, dry, weigh and store.

The technical parameters for preparing amalgam electrodes by dipping reduction method are preferably: HgCl _{concentration 0.01mol} /L, dipping temperature 60°C, dipping time 50 minutes, SnCl concentration 4%, reduction temperature 60°C, reduction time 40 minutes.

The platinum-plated electrode on the ion exchange membrane obtained by the above method is used for electrochemical reaction using the gas/liquid phase benzene hydrogenation-water electrolysis reaction device in Figure 1. The electrolysis temperature and humidified water vapor in the reaction are 70 ° C, and the reference electrode is saturated. Calomel electrode; electrolytic test medium: the cathode is benzene vapor, which is carried by nitrogen into the cathode from the air inlet, the flow rate is 60ml/min; the anode chamber is 0.5mol/L sulfuric acid.

The reaction product is analyzed by chromatography, and cyclohexane and cyclohexene, the products of hydrogenation of benzene, can be obtained, and hydrogen is also present as a by-product, and the current efficiency reaches 40%.

Example 3

Silver-plating on the ion-exchange membrane is carried out using the same immersion reduction method as in Example 1: the extraction conditions are: silver ammonium complex salt solution [Ag(NH ₃ ) ₂ ] ⁺ concentration 0.002mol/L, 2% formaldehyde solution; The temperature of the device is controlled at 90°C, ultrasonic constant temperature impregnation is about 30 minutes, and the formaldehyde solution preheated to 50°C is poured into the reactor for reduction, and the reduction reaction time is 5 minutes.

Preparation of silver amalgam by chemical deposition method: prepare silver-plated ion exchange membrane, the reaction conditions are preferably: HgCl concentration _0.005mol /L, _SnCl concentration 6%, reaction temperature 20°C, reaction time 6 hours.

Example 4

Silver-plating on the ion-exchange membrane is carried out using the same immersion reduction method as in Example 1: the extraction conditions are: silver ammonium complex salt solution [Ag(NH ³ ) ₂ ] ⁺ concentration 0.2mol/L, 0.1% formaldehyde solution; The temperature of the device is controlled at 50°C, ultrasonic constant temperature impregnation is about 40 minutes, and the formaldehyde solution preheated to 50°C is poured into the reactor for reduction, and the reduction reaction time is 2 hours.

The amalgam electrode is prepared by the same impregnation reduction method as in Example 1: the parameters are preferably: HgCl Concentration _0.002mol /L, immersion temperature 90°C, immersion time 30 minutes, _SnCl Concentration 6%, reduction temperature 20°C, reduction The time is 120 minutes.

Example 5

Adopt the same dipping reduction method as in Example 4 to plate silver on the ion-exchange membrane: the extraction conditions are: silver ammonium complex salt solution [Ag(NH ₃ ) ₂ ] ⁺ concentration 0.2mol/L, 0.1% formaldehyde solution; The temperature of the device is controlled at 50°C, ultrasonic constant temperature impregnation is about 40 minutes, and the formaldehyde solution preheated to 50°C is poured into the reactor for reduction, and the reduction reaction time is 2 hours.

The amalgam electrode is prepared by the same impregnation reduction method as in Example 4: the parameters are preferably: HgCl Concentration _0.02mol /L, immersion temperature 30°C, immersion time 90 minutes, _SnCl Concentration 0.1%, reduction temperature 90°C, reduction Time 5 minutes.

The present invention provides a silver amalgam research electrode under the same conditions. When the above electrochemical reaction is a liquid-liquid reaction, the design principle of the reaction device is the same, except that the outside of the cathode plate communicates with the cathode reaction chamber.

In the experiment, a platinum-plated ion-exchange membrane electrode was used as a research electrode, and the preparation method was similar to that of Example 1. A saturated calomel electrode was used as a reference electrode, and a metal platinum sheet was used as an auxiliary electrode. The electrolyte is 0.5mol/L H ₂ SO ₄ solution. N ₂ was used as the carrier gas (80mL/min), and the experimental temperature was 70°C.

Chromatographic analysis shows that cyclohexane and cyclohexene, the products of hydrogenation of benzene, can be obtained, and hydrogen is also present as a by-product, and the current efficiency reaches 15%. Compared with the results of Examples 1 and 2, the current efficiency is very low.

Claims (5)

1. a method for preparing hydrogen-preparing hydrogen-storing integrated electrode is characterized in that, utilizes the step chemical method that the eelctro-catalyst silver amalgam is plated on the ion-exchange membrane, and being combined as a whole with ion-exchange membrane forms combined electrode.

2. method for preparing hydrogen-preparing hydrogen-storing integrated electrode according to claim 1, it is characterized in that, wherein the step chemical method is meant and plates silver by immersion reduction method on ion-exchange membrane earlier, and then adopts chemical deposition or immersion reduction method to form silver amalgam.

3. method for preparing hydrogen-preparing hydrogen-storing integrated electrode according to claim 2 is characterized in that, wherein immersion reduction method silver plated condition on ion-exchange membrane is [Ag (NH ₃) ₂] ⁺Concentration 0.002-0.02mol/L, dipping temperature 50-90 ℃, dipping time 30-60 minute, concentration of formaldehyde 0.1-2%, reduction temperature 50-90 ℃, recovery time 5-120 minute.

4. method for preparing hydrogen-preparing hydrogen-storing integrated electrode according to claim 2 is characterized in that, wherein the condition of immersion reduction method formation silver amalgam is HgCl ₂Concentration 0.002-0.02mol/L, dipping temperature 30-90 ℃, dipping time 30-90 minute, SnCl ₂Concentration 0.1-6%, reduction temperature 20-90 ℃, recovery time 5-120 minute.

5. method for preparing hydrogen-preparing hydrogen-storing integrated electrode according to claim 2 is characterized in that, wherein the condition of chemical deposition formation silver amalgam is HgCl ₂Concentration 0.005-0.02mol/L, SnCl ₂Concentration 1-6%, temperature of reaction 20-90 ℃, reaction times 2-6 hour.