A flow channel structure of an electrolytic cell for enhancing mass transfer

Abstract

The application discloses a reinforced mass transfer electrolytic cell flow channel structure, which comprises a flow channel field formed on an electrode plate, wherein the flow channel field is composed of flow channel grooves, the groove bottoms of the flow channel grooves are uniformly distributed with a plurality of bottom rotational flow grooves, and the groove walls of the flow channel grooves are uniformly distributed with a plurality of side rotational flow grooves; and the two ends of the bottom rotational flow grooves are communicated with the side rotational flow grooves on the two side groove walls. The electrolytic cell flow channel structure provided by the application can convert the laminar flow of fluid in the traditional flow channel into the rotational twisted flow in the imitation gun barrel rifling flow channel under the condition of low flow rate, so as to enhance the mass transfer of the bulk electrolyte to the electrode surface, and further improve the faraday efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electro-synthesis and hydrogen production, and particularly relates to a flow channel structure of an electrolytic cell for enhancing mass transfer. BACKGROUND

[0002] For the electrolysis reaction of dilute substances in aqueous phase, the mass transfer problem is one of the important factors limiting the industrial application of the electrolysis system. Therefore, analyzing the mass transfer limitation phenomenon in the electrolysis reaction of dilute substances in aqueous phase is crucial for promoting the technical development and practical application of the electrolysis reaction of dilute substances in aqueous phase.

[0003] In the electro-catalytic oxidation / reduction of organic matter, reduction of nitrate, reduction of carbon dioxide and other reactions, the substrate concentration in the electrolyte is usually low. After the electrolysis starts, the substrate on the electrode surface is consumed by the reaction, and the concentration decreases. However, the mass transfer of the substrate in the electrolyte body to the electrode is poor, and the substrate molecules cannot fully contact the electrode surface, which leads to a slow reaction rate and side reactions on the electrode surface.

[0004] However, due to the limitations of single-pass conversion rate and ion exchange membrane, the flow rate cannot be increased to enhance the convective mass transfer in the electrochemical reactor. Therefore, designing a flow channel that can change the flow mode in the flow channel under low flow conditions to enhance the convective mass transfer is a problem that needs to be solved in the field. SUMMARY

[0005] The application is proposed to overcome the shortcomings in the prior art, and aims to provide a flow channel structure of an electrolytic cell for enhancing mass transfer.

[0006] The application is implemented by the following technical solutions:

[0007] A flow channel structure of an electrolytic cell for enhancing mass transfer, comprising a flow channel field formed on an electrode plate, the flow channel field being composed of flow channel grooves, the groove bottoms of the flow channel grooves being uniformly provided with a plurality of bottom rotational flow grooves, and the groove walls of the flow channel grooves being uniformly provided with a plurality of side rotational flow grooves; the two ends of the bottom rotational flow grooves being in communication with the side rotational flow grooves on the two side groove walls.

[0008] In the above technical solution, the cross section of the bottom rotational flow groove and the side rotational flow groove is any one of a hexagon, a triangle or a semicircle.

[0009] In the above technical solution, the included angle between the slotting direction of the bottom rotational flow groove and the direction of the liquid flow is 5°-85°.

[0010] In the above technical solution, the included angle between the slotting direction of the side rotational flow groove and the vertical direction is 5°-85°.

[0011] In the above technical solution, the groove depth of the bottom rotational flow groove and the side rotational flow groove is 0.05 times-0.5 times the groove depth of the flow channel groove.

[0012] In the above technical solution, the groove width of the bottom cyclone groove is 0.1 to 2 times the groove depth of the bottom cyclone groove; the groove width of the side cyclone groove is 0.1 to 2 times the groove depth of the side cyclone groove.

[0013] In the above technical solution, the vertical distance between the adjacent groove walls of the two adjacent bottom cyclone grooves is 0.5 to 3 times the groove width of the bottom cyclone groove.

[0014] In the above technical solution, the vertical distance between the adjacent groove walls of the two adjacent side cyclone grooves is 0.5 to 3 times the groove width of the side cyclone groove.

[0015] In the above technical solution, the groove depth of a single flow channel groove is 0.5 to 5 mm; the groove width of a single flow channel groove is 0.5 to 5 mm.

[0016] In the above technical solution, the square area where the flow channel field is located has a length of 10 to 500 mm and a width of 10 to 500 mm.

[0017] In the above technical solution, the flow channel field is Figure 2 any one of a single-channel serpentine flow channel field, a straight-channel parallel flow channel field, a multi-channel serpentine flow channel field, a mixed serpentine flow channel field, or a cross-finger flow channel field as shown in the drawings.

[0018] In the above technical solution, when the flow channel field is a single-channel serpentine flow channel field, the flow channel field is a square area composed of a single serpentine coiled flow channel groove;

[0019] When the flow channel field is a multi-channel serpentine flow channel field, the flow channel field is a square area composed of multiple serpentine coiled flow channel grooves, and the multiple flow channel grooves are parallel to each other;

[0020] When the flow channel field is a straight-channel parallel flow channel field, the flow channel field is a square area composed of multiple straight-line flow channel grooves arranged in parallel;

[0021] When the flow channel field is a mixed serpentine flow channel field, the flow channel field is a square area composed of multiple serpentine coiled flow channel grooves and straight-line flow channel grooves arranged in parallel and connected in a mixed arrangement;

[0022] When the flow channel field is a cross-finger flow channel field, the flow channel field is a directional structure composed of two groups of cross-shaped flow channel grooves, the cross-shaped flow channel groove is composed of a horizontal groove and multiple vertical grooves perpendicular to the horizontal groove, the multiple vertical grooves are arranged at intervals, the vertical grooves of one group of cross-shaped flow channel grooves are inserted into the gap between the two vertical grooves of the other group of cross-shaped flow channel grooves; the inlet and outlet flow channels of the cross-finger flow channel field are not connected and the fingers are crossed.

[0023] An electrolytic cell with the aforementioned reinforced mass transfer electrolytic cell flow channel structure; the material of the electrode plate is selected from any one of titanium, stainless steel, nickel or graphite; the central reaction area of the electrode plate is 10cm*10cm.

[0024] A reactor with the aforementioned electrode plate.

[0025] The beneficial effects of the present application are:

[0026] The present application provides a reinforced mass transfer electrolytic cell flow channel structure, which can convert the laminar flow of fluid in the traditional flow channel into the rotating twisted flow in the imitation gun barrel rifling flow channel under low flow rate conditions to enhance the mass transfer of the bulk electrolyte to the electrode surface, thereby improving the Faraday efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural schematic diagram of the electrode plate with the reinforced mass transfer electrolytic cell flow channel structure of the present application;

[0028] Figure 2 is a structural schematic diagram of the five flow channel fields involved in the present application (a, single-channel serpentine flow channel field; b, straight-channel parallel flow channel field; c, multi-channel serpentine flow channel field; d, mixed serpentine flow channel field; e, cross-finger flow channel field);

[0029] Figure 3 is a comparison diagram of the Faraday efficiency, yield, selectivity and yield of 5-hydroxymethylfurfural (HMF) oxidation to 2,5-furan dicarboxylic acid (FDCA) coupled with hydrogen production under different current densities in the electrochemical reactor of the present application and the electrochemical reactor with the traditional flow channel structure in Example 2 of the present application;

[0030] Figure 4 is a structural schematic diagram of the electrode plate with the traditional flow channel structure.

[0031] 1, electrode plate; 2, flow channel groove; 3, inlet groove; 4, outlet groove; 5, bottom cyclone groove.

[0032] For those of ordinary skill in the art, other related drawings can be obtained from the above drawings without creative labor. DETAILED DESCRIPTION

[0033] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the present application will be further described below in conjunction with the drawings of the specification and through specific embodiments.

[0034] Example 1

[0035] The application discloses a flow channel structure of an electrolytic cell for strengthening mass transfer, which comprises a flow channel field formed on an electrode plate, wherein the flow channel field is a multi-channel serpentine flow channel field, and the multi-channel serpentine flow channel field is a square structure composed of a plurality of serpentine coiled flow channel grooves 2; the plurality of flow channel grooves 2 are parallel to each other.

[0036] The flow channel groove 2 is composed of a plurality of horizontal segments and a plurality of vertical segments, and the vertical segments are arranged at the bending positions of the flow channel groove 2.

[0037] The bottom of the horizontal segment of the flow channel groove 2 is uniformly provided with a plurality of interval arranged bottom rotational flow grooves 5, and the sidewall of the horizontal segment of the flow channel groove 2 is uniformly provided with a plurality of interval arranged side rotational flow grooves, and the two ends of the bottom rotational flow grooves are communicated with the side rotational flow grooves on the two sidewalls.

[0038] The cross section of the bottom rotational flow groove 5 and the side rotational flow groove is a semicircle with a radius of 0.2 mm.

[0039] The included angle between the slotting direction of the bottom rotational flow groove 5 and the liquid flow direction is 45°.

[0040] The included angle between the slotting direction of the side rotational flow groove and the vertical direction is 45°.

[0041] The groove depth of the bottom rotational flow groove 5 and the side rotational flow groove is 0.2 mm.

[0042] The groove width of the bottom rotational flow groove 5 and the side rotational flow groove is 0.5 mm.

[0043] The vertical distance between the adjacent sidewalls of two adjacent bottom rotational flow grooves 5 is 0.5 mm.

[0044] The vertical distance between the adjacent sidewalls of two adjacent side rotational flow grooves is 0.5 mm.

[0045] The groove depth of the flow channel groove is 1 mm.

[0046] The groove width of the flow channel groove is 2 mm.

[0047] The total groove length of the flow channel groove in the liquid flow direction is 100 mm.

[0048] The liquid inlet and the liquid outlet of the flow channel groove 2 are diagonally arranged.

[0049] The front end of the liquid inlet of the flow channel groove 2 is provided with an inlet groove 3, the inlet groove 3 is communicated with the liquid inlets of the plurality of flow channel grooves 2, and the inlet groove 3 is communicated with the liquid inlet of the electrode plate 1.

[0050] The end of the liquid outlet of the flow channel groove 2 is provided with an outlet groove 4, the outlet groove 4 is communicated with the liquid outlets of the plurality of flow channel grooves 2, and the outlet groove 4 is communicated with the liquid outlet of the electrode plate 1.

[0051] The inlet groove 3 and the outlet groove 4 are vertically arranged.

[0052] The material of the polar plate 1 is titanium, and the central reaction area covered by the flow channel site is 10 cm*10 cm.

[0053] Example 2

[0054] An electrolytic cell, the anode plate of which has the reinforced mass transfer electrolytic cell flow channel structure described in Example 1;

[0055] An electrolytic cell is assembled by taking nickel electrodeposited on foamed nickel as an anode and taking sprayed ruthenium oxide on a cation exchange membrane as a membrane electrode cathode, and an experiment of electrocatalytic HMF oxidation to prepare FDCA under alkaline conditions is carried out.

[0056] The electrolyte is 1.5M KOH, the HMF concentration is 300mM, the flow mode is single-pass flow, and the test is carried out under constant current conditions, and the current density is 400, 500, 600mA cm -2 .

[0057] In the electrolytic cell assembled with the traditional flow channel structure, the conversion rates under three current densities are 88.45%, 81.89%, and 81.89% respectively; in the electrolytic cell assembled with the flow channel structure of the application, the conversion rates under three current densities are 88.45%, 88.32%, and 86.05% respectively.

[0058] The electrochemical reactor with the polar plate having the traditional flow channel structure as shown in Figure 4 , and the electrochemical reactor with the polar plate having the flow channel structure of the application are used to carry out the conversion rate, faradaic efficiency, yield, selectivity and yield of 5-hydroxymethylfurfural (HMF) oxidation to 2,5-furan dicarboxylic acid (FDCA) coupling hydrogen production under different current densities, and the specific numerical values are compared in Table 1 and Figure 3 ;

[0059] Table 1

[0060]

[0061] From Table 1, it can be seen that the faradaic efficiency of FCDA (>88%), yield (>81%), selectivity (>88%) and yield of the electrolytic cell assembled with the flow channel structure of the application are all significantly higher than those of the electrolytic cell assembled with the traditional flow channel structure, and from the data in Table 1 and Figure 3 , it can be seen that the faradaic efficiency, yield, selectivity and yield of FDCA in the reactor with the flow channel structure of the application are all higher under the same current density, which proves the superiority of the application compared with the traditional flow channel structure.

[0062] Example 3

[0063] An electrolytic cell, the cathode plate of which has the reinforced mass transfer electrolytic cell flow channel structure described in Example 1;

[0064] The experiment of electrocatalytic reduction of HMF to 2,5-furan dimethanol (BHMF) under alkaline conditions was carried out by assembling an electrolytic cell with oxidized foamed copper as the cathode, nickel electrodeposited on foamed nickel as the anode, and an anion exchange membrane as the diaphragm.

[0065] The electrolyte was 1.5M KOH, the HMF concentration was 300mM, the flow mode was single-pass flow, and the test was carried out under constant current conditions with current densities of 400, 500, and 600mA cm -2 .

[0066] In the electrolytic cell equipped with the traditional flow channel structure, the conversion rates under the three current densities were 85.23%, 79.52, and 79.69%, respectively; in the electrolytic cell equipped with the flow channel structure of the application, the conversion rates under the three current densities were 88.65%, 88.44%, and 87.07%, respectively.

[0067] The Faraday efficiency (>87%), yield (>81%), selectivity (>89%), and yield of BHMF in the electrolytic cell equipped with the flow channel structure of the application were significantly higher than those in the electrolytic cell equipped with the traditional flow channel structure, proving the superiority of the application compared with the traditional flow channel structure.

[0068] Example 4

[0069] An electrolytic cell, the cathode plate of which has the mass transfer enhanced electrolytic cell flow channel structure described in Example 1;

[0070] The experiment of electrocatalytic reduction of nitrate (NO3 - ) to ammonia (NH3) under alkaline conditions was carried out by assembling an electrolytic cell with oxidized foamed copper as the cathode, nickel electrodeposited on foamed nickel as the anode, and an anion exchange membrane as the diaphragm.

[0071] The electrolyte was 1.5M KOH, the KNO3 concentration was 300mM, the flow mode was single-pass flow, and the test was carried out under constant current conditions with current densities of 400, 500, and 600mA cm -2 .

[0072] In the electrolytic cell equipped with the traditional flow channel structure, the conversion rates under the three current densities were 88.77%, 80.43, and 79.98%, respectively; in the electrolytic cell equipped with the flow channel structure of the application, the conversion rates under the three current densities were 88.96%, 88.32%, and 87.12%, respectively.

[0073] The Faraday efficiency (>89%), yield (>83%), selectivity (>88%), and yield of NH3 in the electrolytic cell equipped with the flow channel structure of the application were significantly higher than those in the electrolytic cell equipped with the traditional flow channel structure, proving the superiority of the application compared with the traditional flow channel structure.

[0074] Working principle of the present application:

[0075] The reinforced mass transfer electrolytic cell flow channel structure of the present application processes grooves with a certain angle to the flow channel direction on the bottom surface and side surface of the electrolytic cell flow channel, so that a gun barrel rifling structure is presented in the electrolytic cell, which is similar to the gun barrel rifling to make the bullet rotate. The electrolytic cell flow channel structure can force the electrolyte to change from laminar flow to rotational flow in the traditional flow channel under low Reynolds number conditions. The bottom surface grooves in the flow channel have the effect of changing laminar flow to rotational flow, and the side surface grooves can enhance the flow velocity on the catalyst surface, thereby enhancing the mass transfer of the substrate electrolyte liquid phase to the catalyst surface of the electrode, achieving higher Faraday efficiency, substrate conversion rate and product yield.

[0076] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0077] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the meaning of "a plurality of" is two or more.

[0078] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0079] The applicant declares that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by any person skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. An electrode plate, characterized in that: The electrode plate has an electrolytic cell flow channel structure that enhances mass transfer. The flow channel structure includes a flow field formed on the electrode plate, which consists of at least one flow channel groove. Multiple bottom swirling grooves are evenly distributed on the bottom of the flow channel groove, and multiple side swirling grooves are evenly distributed on the walls of the flow channel groove. The two ends of the bottom swirling groove are connected to the side swirling grooves on the side walls. The angle between the opening direction of the bottom swirling groove and the liquid flow direction is 5° to 85°. The angle between the opening direction of the side swirling groove and the vertical direction is 5° to 85°. The groove depths of both the bottom swirling groove and the side swirling groove are... The width of the bottom swirling groove is 0.05 to 0.5 times the depth of the flow channel groove; the width of the bottom swirling groove is 0.1 to 2 times the depth of the bottom swirling groove; the width of the side swirling groove is 0.1 to 2 times the depth of the side swirling groove; the vertical distance between adjacent walls of two adjacent bottom swirling grooves is 0.5 to 3 times the width of the bottom swirling groove; the vertical distance between adjacent walls of two adjacent side swirling grooves is 0.5 to 3 times the width of the side swirling groove; the depth of the flow channel groove is 0.5 mm to 5 mm; the width of the flow channel groove is 0.5 mm to 5 mm.

2. The electrode plate according to claim 1, characterized in that: The cross-section of the bottom swirling groove and the side swirling groove can be any one of hexagonal, triangular or semi-circular.

3. The electrode plate according to claim 1, characterized in that: The square area containing the flow channel field has a length and width of 10mm to 500mm.

4. The electrode plate according to claim 1, characterized in that: The flow field can be any one of the following: single-channel serpentine flow field, straight-channel parallel flow field, multi-channel serpentine flow field, mixed serpentine flow field, or cross-finger flow field.

5. The electrode plate according to claim 1, characterized in that: When the flow channel field is a single-channel serpentine flow channel field, the flow channel field is a square area composed of a serpentine flow channel groove; When the flow field is a multi-channel serpentine flow field, the flow field is a square area composed of multiple serpentine flow channels, and the multiple flow channels are parallel to each other. When the flow channel field is a straight-channel parallel flow channel field, the flow channel field is a square area composed of multiple parallel straight-line flow channel grooves; When the flow channel field is a hybrid serpentine flow channel field, the flow channel field is a square area composed of multiple serpentine flow channel grooves and parallel straight flow channel grooves arranged in a mixed and connected manner. When the flow channel field is a cross-finger flow channel field, the flow channel field is a directional structure composed of two sets of mountain-shaped flow channel grooves. The mountain-shaped flow channel groove is composed of a horizontal groove and multiple vertical grooves perpendicular to the horizontal groove. The multiple vertical grooves are arranged at intervals. The vertical groove of one set of mountain-shaped flow channel grooves is inserted into the gap between the two vertical grooves of the other set of mountain-shaped flow channel grooves. The inlet and outlet flow channels of the cross-finger flow channel field are not connected to each other and are finger-shaped and cross.

6. An electrolytic cell, characterized in that: It has the electrode plate as described in claim 1.

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