A method for electrocatalytic hydrodehalogenation of haloacetic acids in water by using a ruthenium / nickel hydroxide catalyst
By using an electrochemical method with a ruthenium/nickel hydroxide catalyst, haloacetic acid is selectively hydrogenated to acetic acid, solving the problems of incomplete dehalogenation and high cost of precious metals in existing technologies, and achieving efficient conversion of haloacetic acid and high acetic acid yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2026-04-08
- Publication Date
- 2026-06-05
AI Technical Summary
Existing electrochemical methods do not achieve complete dehalogenation at room temperature and pressure, and the use of precious metal rhodium catalysts is costly and difficult to apply on a large scale. Furthermore, the catalytic activity of existing ruthenium-modified catalytic electrodes needs to be improved.
A conductive material with surface-modified ruthenium/nickel hydroxide was used as the catalytic cathode, and water was used as the hydrogen source. The haloacetic acid was hydrogenated and dehalogenated to acetic acid by an electrochemical method. An inexpensive ruthenium/nickel hydroxide catalyst was used to improve catalytic activity and selectivity.
It improves catalytic activity and acetic acid selectivity, reduces the cost of using precious metals, and achieves high efficiency in the dehalogenation of haloacetic acids to acetic acid conversion and yield.
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Abstract
Description
(I) Technical Field
[0001] This invention belongs to the field of electrochemical water treatment, specifically relating to a method for electrochemically hydrogenating and dehalogenating haloacetic acid in water into acetic acid using a conductive material with surface-modified ruthenium / nickel hydroxide as the catalytic cathode and water as the hydrogen source. (II) Background Technology
[0002] Haloacetic acids are common halogenated organic pollutants in drinking water, surface water, and groundwater. These pollutants are characterized by low concentration, high toxicity, and difficulty in treatment. If left uncontrolled or untreated, they can cause great harm to the ecological environment and human health. Electrochemical methods using palladium-modified conductive materials as catalytic cathodes can remove haloacetic acids from water at room temperature and pressure, but this method suffers from incomplete dehalogenation. Taking the electrochemical catalytic hydrogenation dechlorination of trichloroacetic acid in water as an example, current electrochemical catalytic hydrogenation methods usually produce a high proportion of monochloroacetic acid as the final product [Electrochimica Acta 232 (2017) 13–21], while the toxicity of monochloroacetic acid is nearly 50 times that of trichloroacetic acid [Fundam. Appl. Toxicol. 17,240–253 (1991)].
[0003] To address this, we developed an electrochemical catalytic hydrogenation method using rhodium-containing catalysts. Hydrogen in this method is generated in situ by water electrolysis, enabling the highly selective hydrogenation and dehalogenation of various haloacetic acids to acetic acid [Nature Water, 2023, 1(1):95-103]. Unfortunately, the rhodium catalyst used in this method is too expensive, making large-scale application difficult. Recently, we developed a ruthenium-modified catalytic electrode for the electrocatalytic hydrogenation and dehalogenation of haloacetic acids and halomethanes [CN202411949720.2]. Although the ruthenium-modified catalytic electrode can highly selectively hydrogenate and dehalogenate haloacetic acids and halomethanes to acetic acid and methane, its catalytic activity needs further improvement. (III) Summary of the Invention
[0004] The purpose of this invention is to provide a method for the electrocatalytic hydrogenation and dehalogenation of haloacetic acid in water using a ruthenium / nickel hydroxide catalyst. The method uses a conductive material with a surface modified ruthenium / nickel hydroxide as the catalytic cathode and water as the hydrogen source to electrochemically hydrogenate and dehalogenate haloacetic acid in water into acetic acid. This method not only reduces the unit price of precious metals but also has the advantage of high dehalogenation selectivity.
[0005] The technical solution adopted in this invention is:
[0006] This invention provides a method for the electrocatalytic hydrogenation and dehalogenation of haloacetic acid in water using a ruthenium / nickel hydroxide catalyst. The method uses a conductive material with a surface modified ruthenium / nickel hydroxide as the catalytic cathode, with a cathode potential of -0.3 to -1.0 V vs. a silver / silver chloride reference electrode (saturated potassium chloride aqueous solution), and uses water as the hydrogen source to electrochemically hydrogenate and dehalogenate haloacetic acid in water into acetic acid.
[0007] Furthermore, the haloacetic acid is trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, tribromoacetic acid, dibromoacetic acid, or monobromoacetic acid.
[0008] Furthermore, the conductive material is any conductive solid material that is chemically stable under the reaction conditions, including metallic materials and carbon materials.
[0009] Furthermore, the metallic materials include nickel, copper, stainless steel, etc.; the carbon materials include carbon paper, activated carbon, carbon fiber, graphite felt, foamed glass carbon, etc.
[0010] Furthermore, the cathode is Ru / Ni(OH)2 / Ni, Ru / Ni(OH)2 / stainless steel, Ru / Ni(OH)2 / graphite felt, or Ru / Ni(OH)2 / carbon paper.
[0011] Furthermore, the temperature range of the hydrogenation dehalogenation reaction is 10~40℃.
[0012] Furthermore, the concentration range of haloacetic acid in the water is 10 μg / L to 1 g / L.
[0013] Furthermore, the pH range of the water body is 3 to 11.
[0014] The content of ruthenium and nickel hydroxide on the catalytic cathode surface and the reaction time used in this invention can be varied according to the concentration of haloacetic acid. The Ru content is 0.1~2 mg / cm³. 2 Preferred concentration: 1 mg / cm 2 The nickel hydroxide content is 0.5~10 mg / cm³. 2 2 mg / cm 2 .
[0015] The method for modifying conductive materials with ruthenium / Ni(OH)₂ according to this invention can be performed using a hydrothermal method or a brush coating method using Nafion as a binder. The type of electrochemical reactor and the anode material are not critical factors. The modification can be carried out in a diaphragm-based electrochemical reactor or a diaphragm-free electrochemical reactor. The anode material can be any material stable in the reaction system, such as a titanium anode or a noble metal-modified titanium anode (iridium oxide-modified titanium anode).
[0016] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects: (1) Compared with the Ru / conductive material catalytic electrode, under the same Ru loading conditions, the Ru / Ni(OH)2 catalytic activity is higher, the trichloroacetic acid conversion rate is 9% higher, the acetic acid yield is 14% higher, and the acetic acid selectivity is 5% higher. (2) Compared with the Ni(OH)2 / conductive material catalytic electrode, under the same Ni(OH)2 loading conditions, the Ru / Ni(OH)2 catalytic activity is higher, the trichloroacetic acid conversion rate is 75% higher, the acetic acid yield is 93% higher, and the acetic acid selectivity is 78% higher. (3) Compared with the Pd / conductive material catalytic electrode, under the same noble metal loading conditions, the acetic acid yield is 87% higher, and the acetic acid selectivity is 87% higher. (4) Compared with the Ru / Cu(OH)2 / conductive material catalytic electrode, under the same Ru loading conditions, the acetic acid yield is 7% higher, the acetic acid yield is 17% higher, and the acetic acid selectivity is 11% higher. (iv) Specific implementation methods
[0017] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:
[0018] In the following examples, unless otherwise specified, the electrochemical reactor and catalytic electrode were provided by Hangzhou Sai'ao Electrochemical Instrument Co., Ltd.
[0019] Conversion rate C = (C0 - C1) / C0 × 100%, Yield Y = C2 / C0 × 100%, Selectivity S = Y / C × 100%
[0020] Where C0 is the initial molar concentration of reactants, C1 is the molar concentration of reactants at the end of the reaction, and C2 is the molar concentration of the target product at the end of the reaction.
[0021] Comparative Example 1: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water—Ru / Ni as cathode
[0022] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Ru-modified nickel foam as the cathode (Ru / Ni, 2×4 cm⁻¹), 2 Ru content 1 mg / cm 2 ), iridium oxide-modified titanium as the anode (2×4 cm) 2 Iridium oxide content 1 mg / cm 250 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH adjusted to 7.2 with sodium hydroxide, temperature 20~30℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 40 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 91%, the yield of acetic acid was 85%, and the selectivity of acetic acid was 93%.
[0023] Comparative Example 2: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water—Ni(OH)2-modified nickel foam as cathode
[0024] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Ni(OH)2-modified nickel foam as the cathode (Ni(OH)2 / Ni, 2×4 cm⁻¹),... 2 Ni(OH)2 content 2 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4 cm) 2 Iridium oxide content 1 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH adjusted to 7.2 with sodium hydroxide, temperature 20~30℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 40 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 25%, the yield of acetic acid was 5%, and the selectivity of acetic acid was 20%.
[0025] Comparative Example 3: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water—Pd / Ni(OH)2 / Ni as cathode
[0026] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Pd / Ni(OH)2 modified nickel foam as the cathode (Pd / Ni(OH)2 / Ni, 2×4 cm⁻¹),... 2 Pd content 1 mg / cm 2 Ni(OH)2 content 2 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4 cm) 2 Iridium oxide content 1 mg / cm 250 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH adjusted to 7.2 with sodium hydroxide, temperature 20~30℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 40 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 100%, the yield of acetic acid was 11%, and the selectivity of acetic acid was 11%.
[0027] Comparative Example 4: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water—Ru / Cu(OH)2 / Ni as cathode
[0028] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Ru / Cu(OH)2 modified nickel foam as the cathode (Ru / Cu(OH)2 / Ni, 2×4 cm⁻¹),... 2 Ru content 1 mg / cm 2 Cu(OH)2 content 2 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4 cm) 2 Iridium oxide content 1 mg / cm 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH adjusted to 7.2 with sodium hydroxide, temperature 20~30℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 40 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 93%, the yield of acetic acid was 81%, and the selectivity of acetic acid was 87%.
[0029] Example 1: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water
[0030] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Ru / Ni(OH)2 modified nickel foam as the cathode (Ru / Ni(OH)2 / Ni, 2×4 cm⁻¹),... 2 Ru content 1 mg / cm 2 Ni(OH)2 content 2 mg / cm³ 2 Titanium is the anode (2×4 cm) 250 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH adjusted to 7.2 with sodium hydroxide, temperature 20~30℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 40 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 100%, the yield of acetic acid was 98%, and the selectivity of acetic acid was 98%.
[0031] Compared to Comparative Example 1, the conversion rate of trichloroacetic acid was 9% higher, the yield of acetic acid was 14% higher, and the selectivity of acetic acid was 5% higher within the same reaction time; compared to Comparative Example 2, the conversion rate of trichloroacetic acid was 75% higher, the yield of acetic acid was 93% higher, and the selectivity of acetic acid was 78% higher within the same reaction time; compared to Comparative Example 3, the yield of acetic acid was 87% higher, and the selectivity of acetic acid was 87% higher within the same reaction time; compared to Comparative Example 4, the yield of acetic acid was 7% higher, the yield of acetic acid was 17% higher, and the selectivity of acetic acid was 11% higher within the same reaction time.
[0032] Example 2 Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water—diaphragmless electrolyzer
[0033] A diaphragmless electrolytic cell was used as the reactor, and Ru / Ni(OH)2 modified nickel foam was used as the cathode (Ru / Ni(OH)2 / Ni, 2×4 cm). 2 Ru content 1 mg / cm 2 Ni(OH)2 content 2 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4 cm) 2 Iridium oxide content 1 mg / cm³ 2 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH adjusted to 7.2 with sodium hydroxide, temperature 20~30℃) was used as the electrolyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 40 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 100%, the yield of acetic acid was 99%, and the selectivity of acetic acid was 99%.
[0034] Examples 3-5: Electrochemical hydrogenation dehalogenation reactions of different haloacetic acids in tap water
[0035] The trichloroacetic acid in Example 1 was replaced with the same amount of the reactants shown in Table 1, and other operations were the same. The results are shown in Table 1. It can be seen that various haloacetic acids can be electrochemically hydrogenated and dehalogenated to acetic acid with high selectivity under the experimental conditions of Example 1.
[0036] Table 1 Electrochemical hydrogenation dehalogenation reactions of different haloacetic acids in tap water
[0037]
[0038] Unless otherwise specified, the reaction conditions are the same as in Example 1.
[0039] Examples 6-11 Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water—under different reaction conditions
[0040] The method of Example 1 was used, with differences and results shown in Table 2; the remaining operations were the same. It can be seen that the conductive materials of the catalytic electrode are nickel, stainless steel, carbon paper, and graphite felt, with a Ru content of 0.1~2 mg / cm³. 2 The nickel hydroxide content is 0.5~10 mg / cm³. 2 2 mg / cm 2 With a temperature range of 10~40℃, a trichloroacetic acid concentration in the water range of 10 μg / L~1g / L, a catholyte pH of 3~11, and a cathodic potential of -0.3~1.0 V, trichloroacetic acid can be selectively converted into acetic acid using a silver / silver chloride reference electrode (saturated potassium chloride aqueous solution).
[0041] Table 2 Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid—under different reaction conditions
[0042]
[0043] Unless otherwise specified, the reaction conditions are the same as in Example 1. a The cathode material was prepared using a hydrothermal method. b The cathode material was prepared by coating.
Claims
1. A method for the electrocatalytic hydrogenation dehalogenation of haloacetic acid in water using a ruthenium / nickel hydroxide catalyst, characterized in that... The method uses a conductive material with surface-modified ruthenium / nickel hydroxide as the catalytic cathode, with a cathode potential of -0.3 to -1.0 V vs. silver / silver chloride reference electrode, and water as the hydrogen source to electrochemically hydrogenate and dehalogenate haloacetic acid in water into acetic acid.
2. The method as described in claim 1, characterized in that, The haloacetic acid is trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, tribromoacetic acid, dibromoacetic acid, or monobromoacetic acid.
3. The method as described in claim 1, characterized in that, The conductive material is any conductive solid material that is chemically stable under the reaction conditions, including metallic materials and carbon materials.
4. The method as described in claim 3, characterized in that, The metallic materials include nickel, copper, and stainless steel; the carbon materials include carbon paper, activated carbon, carbon fiber, graphite felt, and foamed glass carbon.
5. The method as described in claim 1, characterized in that, The cathode is Ru / Ni(OH)2 / Ni, Ru / Ni(OH)2 / stainless steel, Ru / Ni(OH)2 / graphite felt, or Ru / Ni(OH)2 / carbon paper.
6. The method as described in claim 1, characterized in that, The temperature range for the hydrogenation dehalogenation reaction is 10~40℃.
7. The method as described in claim 1, characterized in that, The concentration range of haloacetic acid in the water is 10 μg / L to 1 g / L.
8. The method as described in claim 1, characterized in that, The pH range of the water body is 3 to 11.