A method for spraying a catalyst slurry and a method for preparing a circular membrane electrode CCM

Abstract

The application discloses a spraying method of catalyst slurry and a preparation method of a circular membrane electrode CCM, and belongs to the technical field of hydrogen energy. The application adopts a circular spraying path to perform one-way segmented spraying on a proton membrane, and finally solves the problem of serious catalyst loss in a concentric circle forming mode. The method can improve the noble metal loading by 38%-45%, and the catalyst utilization rate can be remarkably improved by adopting the process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen energy, and relates to a spraying method of catalyst slurry and a preparation method of a circular membrane electrode CCM. BACKGROUND

[0002] Hydrogen energy is a kind of secondary energy with abundant sources, green and low carbon, and wide application, which can help large-scale consumption of renewable energy, realize large-scale peak shaving and cross-season and cross-region energy storage of power grids, and accelerate the low-carbonization of the fields of industry, construction and transportation.

[0003] The membrane electrode is the core of the PEM water electrolysis hydrogen production reaction, and determines the performance, service life and cost of the final membrane electrode product, and the preparation method and structural design thereof are closely related to the PEM water electrolysis performance. At present, the PEM membrane electrode generally adopts a CCM structure (catalyst coated membrane), that is, catalyst slurry is coated on both sides of a proton exchange membrane.

[0004] At present, there are relevant researches on the spraying process. For example, the patent application with the publication number CN116264284A discloses a spraying process of catalyst slurry and a preparation method of a fuel cell CCM. The spraying path includes an interdigitated serpentine path I and a serpentine path II, and the serpentine path I and the serpentine path II each include a straight path and a turning path. The patent application controls the spraying speed and the slurry flow rate in the catalyst layer spraying process, adopts the interdigitated serpentine path for spraying, and controls the temperature of the drying platform in sections, so that the speed of the turning path spraying is 1.1-2 times faster than the speed of the straight path spraying, the flow rate of the turning path spraying is 0.1-0.9 times the flow rate of the straight path spraying, and a blank area is left between the two straight paths that are sprayed in turn, so as to avoid the slurry accumulation phenomenon in the turning path spraying, and solve the problem of high thickness of the catalyst layer at the edge of the catalyst layer caused by the traditional uniform speed / uniform flow rate spraying.

[0005] In addition, the invention patent with the authorization number CN112599793B discloses a CCM coating process for realizing anti-swelling by using a protective back film, catalyst slurry is coated on a first surface of a proton exchange membrane to form a first catalyst layer after drying; a protective film with a flexible carrier layer is prepared, a protective film with a flexible carrier layer is attached to the first surface of the proton exchange membrane containing the first catalyst layer, and the protective film and the proton exchange membrane are pressed together; catalyst slurry is coated on a second surface of the proton exchange membrane to form a second catalyst layer after drying, and a membrane electrode with a temporary protective film is obtained; finally, the membrane electrode with the temporary protective film is subjected to heat treatment or ultraviolet (UV) irradiation to peel off the temporary protective layer, and a membrane electrode is obtained; if heat treatment is selected, a nano-oxide solution needs to be sprayed on the surface of the first catalyst layer before the first catalyst layer is dried. The invention effectively avoids the swelling of the proton exchange membrane in the process of preparing the membrane electrode.

[0006] When a circular membrane electrode is prepared by spraying, a square spraying area is usually positioned and formed, then a circular spraying tool is used to cover the proton membrane, and a circular membrane electrode is formed by one-way or two-way alternate filling in the form of coating lines, and finally the catalyst layer is formed by removing the solvent through heating and drying. However, this spraying method can cause serious waste of catalyst slurry, low utilization rate of catalyst, and high cost of membrane electrode.

[0007] Therefore, more spraying processes are needed to adapt to more membrane electrode processing processes. SUMMARY

[0008] To solve the above technical problems, the present application proposes a one-way segmented spraying method for proton membranes by using a circular spraying path to solve the problem of serious catalyst loss in a concentric circle manner, so as to improve the utilization rate of catalyst and save the cost of membrane electrode.

[0009] To achieve the above purpose, the specific technical solutions of the present application are as follows:

[0010] The present application provides a spraying method for catalyst slurry, which sprays catalyst slurry on a proton exchange membrane, sprays catalyst slurry on both sides of the proton exchange membrane in a circular path, sprays in a one-way segmented manner, and forms concentric circles after sequential spraying.

[0011] Preferably, the interval of the one-way segmented spraying is 6-7mm. The flow rate of the spraying is 0.6-1.5ml / min, and the spraying speed is 60-100mm / s. In this parameter range, the problem of proton membrane swelling caused by the failure of slurry to dry in time can be avoided.

[0012] Specifically, in the one-way segmented spraying, the starting point of spraying is sequentially sprayed from the center of the concentric circle to the center or from the center to the center of the concentric circle.

[0013] The catalyst in the catalyst slurry is platinum carbon catalyst.

[0014] The present application also provides the application of the spraying method in the preparation of a circular membrane electrode CCM.

[0015] The present application also provides a preparation method of a circular membrane electrode CCM, which prepares catalyst slurry, sprays the catalyst slurry on a proton exchange membrane to prepare a membrane electrode, and obtains the circular membrane electrode CCM, and sprays the catalyst slurry on both sides of the proton exchange membrane by using the spraying method.

[0016] Specifically, the preparation method of the catalyst slurry comprises the following steps:

[0017] The catalyst, perfluorosulfonic acid resin and solvent are mixed and uniformly dispersed to obtain a catalyst slurry.

[0018] The solvent is water and an organic alcohol; the mass ratio of the water and the organic alcohol is 1-2:1.

[0019] The mass ratio of the perfluorosulfonic acid resin to the catalyst is 10:1.

[0020] The dispersion is first ultrasonic dispersion and then shearing by a high-speed homogenizer.

[0021] The present application has the following beneficial effects:

[0022] The present application can avoid catalyst slurry loss caused by excessive spraying by forming concentric circles; the method is simple and fast, and only one circular path needs to be determined, and the next circular path can be set by corresponding interval displacement, and finally concentric circles are formed; in addition, the spraying starting point can be sprayed from outside to inside (from the position far away from the center of the concentric circle to the center) or from inside to outside (from the center to the position far away from the center of the concentric circle).

[0023] That is, the present application adopts a circular spraying path for one-way segmented spraying of a proton membrane, and finally forms a concentric circle process, which can improve the noble metal loading by 38%-45%; the present application process can significantly improve the catalyst utilization rate. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The figure is a spraying process diagram of the present application.

[0025] Figure 2 The figure is a spraying effect diagram in Example 1.

[0026] Figure 3 The figure is a spraying effect diagram in Example 2.

[0027] Figure 4 The figure is a spraying effect diagram in Comparative Example 1. DETAILED DESCRIPTION

[0028] Example 1

[0029] Preparation of catalyst slurry: 0.029 g of platinum carbon catalyst, 0.29 g of perfluorosulfonic acid resin (concentration 5%), 10 g of deionized water and 10 g of n-propanol are weighed, mixed uniformly, then ultrasonic dispersion is carried out by using an ultrasonic machine, the ultrasonic frequency is 75 Hz, and the time is 30 min; shearing is carried out by using a high-speed homogenizer, the speed is 14000 rpm, and the shearing time is 30 min, and finally a uniform slurry is formed.

[0030] Spraying setting: the catalyst slurry spraying process diagram of the present application is as follows: Figure 1The specific steps are as follows: a proton membrane with a size of 76mm*76mm is laid on the operation table, a heating temperature of 90°C is set and vacuum adsorption is performed, the circular size required for spraying is A concentric circular path is set, the starting point of spraying is from the outside to the inside, the first circular path is set to the first point (69, 107.2), the second point (104, 72.2) and the third point (69, 37.2), wherein the interval between adjacent two circular paths is 6mm, the next circular path can be sequentially set until the number of spraying sections of the circular path set is 70 / 2 / 6=6 (rounded, rounded), the spraying flow is set to 0.6ml / min, and the spraying speed is 60mm / s.

[0031] The spraying effect is as shown in Figure 2 The circular spraying area is relatively complete, and the overall catalytic layer is relatively uniform, and there is no obvious excessive spraying phenomenon at the edge.

[0032] Example 2

[0033] Slurry preparation: 0.029g of platinum carbon catalyst, 0.29g of perfluorosulfonic acid resin (concentration 5%), 5g of deionized water and 10g of n-propanol are weighed, the above components are uniformly mixed, and then ultrasonic dispersion is performed by using an ultrasonic machine, the ultrasonic frequency is 75Hz, and the time is 30min; then shearing is performed by using a high-speed homogenizer, the rotating speed is 14000rpm, and the shearing time is 30min, and finally a uniform slurry is formed.

[0034] Spraying setting: a proton membrane with a size of 76mm*76mm is laid on the operation table, a heating temperature of 90°C is set and vacuum adsorption is performed, the circular size required for spraying is A concentric circular path is set, the starting point of spraying is from the inside to the outside, the first circular path is set to the first point (69, 79.2), the second point (76, 72.2) and the third point (69, 65.2), wherein the interval between adjacent two circular paths is 7mm, the next path can be sequentially set until the number of spraying sections of the circular path set is 70 / 2 / 7=5, the spraying flow is set to 1.5ml / min, and the spraying speed is 100mm / s.

[0035] The spraying effect is as shown in Figure 3 The circular spraying area is relatively complete, and the overall catalytic layer is relatively uniform, and there is no obvious excessive spraying phenomenon at the edge.

[0036] Comparative Example 1

[0037] Slurry preparation: 0.029 g of platinum carbon catalyst, 0.29 g of perfluorosulfonic acid resin (concentration 5%), 10 g of deionized water, 10 g of n-propanol were weighed, and the above components were mixed uniformly, and then ultrasonic dispersion was performed using an ultrasonic machine, the ultrasonic frequency was 75 Hz, and the time was 30 min; then a high-speed homogenizer was used for shearing, the speed was 14000 rpm, and the shearing time was 30 min, and finally a uniform slurry was formed.

[0038] Spraying setting: a proton membrane with a size of 76mm*76mm was laid on the operation table, the heating temperature was set to 90 DEG C and vacuum adsorption was performed, and a circular spraying tool was placed The first point (44, 101) and the second point (101, 55) were set as spraying coordinates, and the spraying was performed in the form of a line in a cross shape to alternately fill. The spraying interval was set to 6 mm, the spraying flow was 0.6 ml / min, and the spraying speed was 60 mm / s.

[0039] The spraying effect is shown in Figure 4 The middle circular spraying area is relatively complete, the overall catalytic layer is relatively uniform, but there is obvious excessive spraying phenomenon at the edge.

[0040] The catalytic layer sprayed in the application was detected by an XRF detector to detect the content of platinum in the catalytic layer, and the data are shown in Table 1.

[0041] Table 1

[0042]

[0043] From the table data, it can be seen that the noble metal loadings of example 1 and example 2 are improved compared with comparative example 1, and the improvement range is 38%-45%. The specific reason is that the circular membrane electrode formed by filling in the form of a coating line will have the problem of excessive spraying, and the spraying area formed by the coating line is larger than the circular spraying area, so the catalyst utilization rate can be significantly improved by using the process of the application.

Claims

1. A method for spraying a catalyst slurry, comprising spraying the catalyst slurry onto a proton exchange membrane, characterized in that, The catalyst slurry is sprayed onto both sides of the proton exchange membrane in a circular path. The spraying path adopts unidirectional segmented spraying, and concentric circles are formed after sequential spraying. The interval between the unidirectional segmented spraying is 6-7mm; The spraying flow rate is 0.6-1.5 ml / min, and the spraying speed is 60-100 mm / s; When using unidirectional segmented spraying, the spraying starts from the point furthest from the center of the concentric circles and sprays towards the center, or from the center of the circles and sprays towards the point furthest from the center of the concentric circles.

2. The method for spraying the catalyst slurry according to claim 1, characterized in that, The catalyst in the catalyst slurry is a platinum-carbon catalyst.

3. The application of the spraying method according to claim 1 or 2 in the preparation of circular film electrodes (CCMs).

4. A method for preparing a circular membrane electrode CCM, comprising preparing a catalyst slurry, spraying the catalyst slurry onto a proton exchange membrane to prepare the membrane electrode, thereby obtaining the circular membrane electrode CCM, characterized in that, The catalyst slurry is sprayed onto both sides of the proton exchange membrane using the spraying method described in claim 1 or 2.

5. The preparation method according to claim 4, characterized in that, The method for preparing the catalyst slurry includes the following steps: The catalyst, perfluorosulfonic acid resin and solvent are mixed and dispersed evenly to obtain a catalyst slurry.

6. The preparation method according to claim 5, characterized in that, The solvent is water and an organic alcohol; the mass ratio of water to organic alcohol is 1-2:

1. The mass ratio of perfluorosulfonic acid resin to catalyst is 10:

1.

7. The preparation method according to claim 5, characterized in that, The dispersion process involves first ultrasonic dispersion, followed by shearing using a high-speed homogenizer.

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