A mixed-bed resin for hydrogen fuel cell vehicles and its preparation method

Abstract

This invention discloses a mixed-bed resin for hydrogen fuel cell vehicles and its preparation method. First, styrene and divinylbenzene are used to produce styrene-divinylbenzene copolymer white spheres via suspension polymerization. The obtained white spheres are then sulfonated with H₂SO₄ to obtain a styrene-based gel-type strong acid cation exchange resin with a crosslinking degree of 10%, an average particle size of 0.525 mm, and a wet apparent density of 0.75-0.85 g / ml. Next, the white spheres are immersed in chloromethylation raw materials, and chloromethylation spheres are obtained under the action of a chloromethylation catalyst. The obtained chloromethylation spheres are then placed in a reactor and sequentially subjected to swelling with a swelling agent, reaction with an alkyl tertiary amine, and washing with pure water to obtain a styrene-based gel-type strong base anion exchange resin with a crosslinking degree of 7%, a particle size of 0.63 mm, and a wet apparent density of 0.67-0.72 g / ml. The prepared strong acid cation exchange resin and strong base anion exchange resin are mixed and packaged at a volume ratio of 1:4. This invention improves the exchange capacity of the mixed-bed resin, solves the problem of premature large-scale consumption of single resins, and extends the service life of the ion exchanger.

Description

Technical Field

[0001] This invention relates to the field of fuel cell cooling system technology, and in particular to a mixed-bed resin for hydrogen fuel cell vehicles and its preparation method. Background Technology

[0002] Hydrogen, as a green energy source, meets the requirement of zero-carbon energy emission. Hydrogen fuel cell (PEMFC) vehicles utilize the electrochemical reaction between hydrogen and oxygen to release electrical energy for propulsion. Due to the characteristics of its structure and working principle, hydrogen fuel cell systems generate a significant amount of heat during operation. Both excessively high and low temperatures can degrade the performance of the hydrogen fuel cell system. Therefore, hydrogen fuel cell systems require a thermal management system module to ensure they operate at suitable temperatures. In high-power hydrogen fuel cell commercial vehicle applications, the system employs a water-circulation thermal management control method. However, during fuel cell system operation, ions are released from the pipes and some components, increasing the conductivity of the water-circulating coolant. This generates a high voltage on the bipolar plates of the fuel cell stack, which is then transmitted through the coolant to the entire cooling circulation channel. If the coolant conductivity is too high, the high-voltage operating mode will degrade the insulation performance of the entire system, affecting the vehicle's safety performance. Therefore, current cooling circulation systems install ion exchangers with built-in mixed-bed resin to reduce coolant conductivity and maintain the normal operation of the fuel cell system.

[0003] Analysis of the mixed-bed resin inside the replaced ion exchangers from hydrogen fuel cell vehicles has revealed instances where the anion resin was completely depleted, while the cation resin still retained over 60% of its exchange capacity. Given the characteristics of mixed-bed resin, once a single resin fails, the entire mixed-bed resin can no longer reduce the conductivity of the fuel cell coolant, thus lowering the insulation performance of the battery system. Therefore, the entire ion exchanger in the battery cooling system needs to be replaced, resulting in significant waste of material costs. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies where the anion resin in the ion exchanger of a fuel cell stack system is completely consumed while the cation resin is not consumed in large quantities, and to provide a mixed bed resin for hydrogen fuel cell vehicles and its preparation method.

[0005] The objective of this invention is achieved through the following technical solution: a method for preparing a mixed-bed resin for hydrogen fuel cell vehicles, comprising the following steps,

[0006] S1. Styrene and divinylbenzene are used to produce styrene-divinylbenzene copolymer white spheres by suspension polymerization. The obtained white spheres are sulfonated with H2SO4. By changing the ratio of styrene and divinylbenzene components, a styrene-based gel-type strong acid cation exchange resin with a crosslinking degree of 10%, a particle size of 0.525 mm, and a wet apparent density of 0.75-0.85 g / ml is obtained.

[0007] S2. Styrene and divinylbenzene are used to produce styrene-divinylbenzene copolymer white spheres by suspension polymerization. The obtained white spheres are immersed in chloromethylation raw materials, and chloro spheres are obtained under the action of chloromethylation catalyst. The obtained chloro spheres are then placed in a reaction vessel and subjected to swelling with a swelling agent, reaction with alkyl tertiary amine, and washing with pure water in sequence. By changing the ratio of styrene and divinylbenzene components, a styrene-based gel-type strong base anion resin with a crosslinking degree of 7%, a particle size of 0.63 mm, and a wet apparent density of 0.67-0.72 g / ml is obtained.

[0008] S3. The strong acid cation resin and strong base anion resin are prepared by mixing and filling them at a volume ratio of 1:4.

[0009] Preferably, the suspension polymerization method is carried out according to the following steps: styrene, divinylbenzene and an initiator are added to the reaction system, along with pure water, an organic dispersant, an auxiliary crosslinking agent and a polymerization inhibitor, and suspension polymerization is carried out fully. The pH is adjusted, and the product is washed with water until neutral to obtain the styrene-divinylbenzene copolymer white balls.

[0010] Preferably, the initiator is one or more of benzoyl peroxide, azobisisobutyronitrile, cumene hydroperoxide, and lauroyl peroxide; the organic dispersant is one or more of polyvinyl alcohol, gelatin, starch, methyl cellulose and its derivatives; the auxiliary crosslinking agent is acrylonitrile; and the polymerization inhibitor is methylene blue.

[0011] Preferably, the chloromethylation raw material is paraformaldehyde, formaldehyde aqueous solution, dimethyl acetal, chloromethyl ether, dichloromethyl ether, or chlorosulfonic acid.

[0012] Preferably, the chloromethylation catalyst is one or more of zinc chloride or ferric chloride.

[0013] Preferably, the swelling agent is one or more of dichloroethane, carbon tetrachloride, benzene, and dichlorocyclohexane.

[0014] Preferably, the alkyl tertiary amine is trimethylamine.

[0015] Another objective of this invention is to provide a mixed-bed resin for hydrogen fuel cell vehicles prepared according to the above method.

[0016] The present invention has the following advantages: the degree of cross-linking of the resin determines the volume exchange capacity of the resin. The volume exchange capacity can be increased by increasing the ratio of anion and cation resins. However, the degree of cross-linking of the resin cannot be increased indefinitely. The particle size and porosity of the resin must be taken into account. By reasonably selecting the degree of cross-linking of anion and cation resins, not only is the volume exchange capacity of the anion and cation resins improved, but ion exchange is also facilitated. At the same time, by controlling the mixed bed ratio of anion and cation resins, the premature consumption of a large amount of a single resin can be avoided, which would lead to the overall scrapping of the ion exchanger and extend the service life of the ion exchanger. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] A mixed-bed resin for hydrogen fuel cell vehicles is prepared according to the following method, including the following steps.

[0019] S1. Add 90% styrene, 10% divinylbenzene, and 1% benzoyl peroxide (initiator) to the reaction system, along with pure water, 0.5% polyvinyl alcohol (organic dispersant), 1% acrylonitrile (auxiliary crosslinking agent), and 0.1% methylene blue (polymerization inhibitor). Allow the mixture to undergo suspension polymerization. Adjust the pH and wash the product with water until neutral to obtain the styrene-divinylbenzene copolymer white spheres. Sulfonate the obtained white spheres with H2SO4 to obtain a styrene-based gel-type strong acid cation exchange resin with a crosslinking degree of 10%, an average particle size of 0.525 mm, and a wet apparent density of 0.75-0.85 g / ml.

[0020] S2. Add 93% styrene, 7% divinylbenzene, and 1% benzoyl peroxide (initiator) to the reaction system, along with pure water, 0.5% polyvinyl alcohol (organic dispersant), 1% acrylonitrile (auxiliary crosslinking agent), and 0.1% methylene blue (polymerization inhibitor). Perform suspension polymerization, adjust the pH, and wash the product with water until neutral to obtain the styrene-divinylbenzene copolymer white spheres. Immerse the obtained white spheres in 400% chloromethyl ether, and then prepare chlorinated spheres under the action of 50% ferric chloride (chloromethylation catalyst). Place the obtained chlorinated spheres in a reaction vessel and sequentially pass them through swelling agent dichloroethane, reaction with trimethylamine solution, and washing with pure water to obtain styrene-based gel-type strong styrene with a crosslinking degree of 7%, an average particle size of 0.63 mm, and a wet apparent density of 0.67-0.72 g / ml.

[0021] S3. The strong acid cation resin and strong base anion resin are prepared by mixing and filling them at a volume ratio of 1:4.

[0022] In the preparation of styrene-divinylbenzene copolymer white spheres, initiators can include benzoyl peroxide, as well as other azo initiators or peroxide initiators, including azobisisobutyronitrile, cumene hydroperoxide, and lauroyl peroxide. Organic dispersants can include polyvinyl alcohol, gelatin, starch, methyl cellulose and its derivatives. In the chloromethylation step of the white spheres, in addition to chloromethyl ether, other chloromethylation raw materials can be used for the reaction, including paraformaldehyde, formaldehyde aqueous solution, dimethyl acetal, dichloromethyl ether, and chlorosulfonic acid. At the same time, the chloromethylation catalyst ferric chloride can be replaced with zinc chloride. In addition to dichloroethane, swelling agents can include carbon tetrachloride, benzene, and dichlorocyclohexane.

[0023] Currently available mixed bed resins have a bulk exchange capacity of 2.0-2.5 for cation exchange resins and 1.0-1.2 for anion exchange resins. Therefore, to ensure that the mixed bed resins have a stoichiometric ratio of 1:1 for cation and anion exchange capacity, the mixing ratio between cation and anion resins is usually between 1:1.5 and 1:3. Comparative experiments were conducted using mixing ratios of 1:1.5 and 1:2.

[0024] Comparative Example 1

[0025] A 1:1.5 mixed-bed resin for hydrogen fuel cell vehicles, wherein the strong acid cation resin is selected with a crosslinking degree of 12%, an average particle size of 0.65 mm, and a wet apparent density of 0.77-0.79 g / ml, and the strong base anion resin is selected with a crosslinking degree of 10%, an average particle size of 0.55 mm, and a wet apparent density of 0.67-0.72 g / ml.

[0026] Comparative Example 2

[0027] A 1:2 mixed bed resin for hydrogen fuel cell vehicles, wherein the strong acid cation resin is selected with a crosslinking degree of 10%, an average particle size of 0.65 mm, and a wet apparent density of 0.77-0.79 g / ml, and the strong base anion resin is selected with a crosslinking degree of 7%, an average particle size of 0.55 mm, and a wet apparent density of 0.67-0.72 g / ml.

[0028] The mixed bed resins of the above embodiments and Comparative Examples 1 and 2 were mixed and placed on a sports car for actual experiments. The average speed of the vehicle was 50 km / h. The test results are shown in the table below.

[0029] Ratio (positive: negative) result Example 1:4 After 400 hours (17 days), the anion resin showed a remaining OH- conversion rate of 86.64%, and the cation resin showed a remaining H+ conversion rate of 99.08%. After 900 hours of operation, the remaining cation resin was 19.81%, and the remaining anion resin was 0%. Comparative Example 1 1:1.5 After 200 hours of operation, 94.79% of the cation exchange resin and 0% of the anion exchange resin remained. Comparative Example 2 1:2 After 400 hours of operation, 84.12% of the cation exchange resin and 0% of the anion exchange resin remained.

[0030] As shown in the table above, when the single-component anion resin is used up, the improved mixed bed resin, compared with the comparative mixed bed resin, leaves only 19.81% of the cation resin after the equipment has been running, reducing cation resin waste by 74.98%. At the same time, the operating time is extended from the original 200 hours to 900 hours, greatly increasing the service life of the equipment.

[0031] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing a mixed bed resin for a hydrogen fuel cell vehicle, characterized by, Comprising the following steps, S1. The mass of styrene 90%, divinylbenzene 10% and initiator benzoyl peroxide 1% is added to the reaction system, and pure water, organic dispersant polyvinyl alcohol 0.5%, auxiliary crosslinking agent acrylonitrile 1%, polymerization inhibitor methylene blue 0.1% is added, and the pH is adjusted, and the product is washed to neutral with water, to obtain the styrene-divinylbenzene copolymer white ball, and the prepared white ball is sulfonated with H2SO4 to obtain a styrene-based gel-type strong acid cation resin with a crosslinking degree of 10%, an average particle size of 0.525mm and a wet apparent density of 0.75-0.85g / ml; S2. The mass of styrene 93%, divinylbenzene 7% and initiator benzoyl peroxide 1% is added to the reaction system, and pure water, organic dispersant polyvinyl alcohol 0.5%, auxiliary crosslinking agent acrylonitrile 1%, polymerization inhibitor methylene blue 0.1% is added, and the pH is adjusted, and the product is washed to neutral with water, to obtain the styrene-divinylbenzene copolymer white ball, and the prepared white ball is immersed in chloromethyl ether 400%, and then chloromethylated under the action of chloromethylation catalyst ferric chloride 50% to obtain chloromethylated ball, and then the obtained chloromethylated ball is placed in a reaction kettle, and is sequentially swelled with swelling agent dichloroethane, reacted with trimethylamine solution and washed with pure water, to obtain a styrene-based gel-type strong base anion resin with a crosslinking degree of 7%, an average particle size of 0.63mm and a wet apparent density of 0.67-0.72g / ml; S3. The prepared strong acid cation resin and strong base anion resin are mixed and filled according to a volume ratio of 1:4 to obtain the mixed bed resin.

2. The mixed bed resin for hydrogen fuel cell vehicle prepared by the preparation method of claim 1.