A method for electrocatalytic oxidation of volatile organic pollutants coupled with hydrogen production to high value products

Abstract

The application discloses a method for producing hydrogen by coupling electro-catalytic oxidation of volatile organic pollutants into high-value products. The specific steps include: sending the volatile organic pollutants into a compressor for compression, sending the compressed volatile organic pollutants into a condenser, wherein the organic steam changes from gaseous state into liquid state and then enters an electro-catalytic system for electro-catalytic oxidation process. The electro-catalytic system adopts a three-electrode system, including a reference electrode, a working electrode and a counter electrode, the constant voltage interval is 1.2-2.0 V, the electrolyte is an alkaline solution with a concentration of 0.1-2 M, and the high-value products can be obtained by separation and extraction after electrolysis. The application can completely remove harmful substances in the volatile organic pollutants and convert them into high-value chemical products or raw materials, and hydrogen is generated at the cathode, the reaction condition is mild, no secondary pollution is generated, and the application has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for coupling hydrogen production with electrocatalytic oxidation of volatile organic pollutants to high-value products, belonging to the field of electrocatalytic oxidation of organic matter conversion. BACKGROUND

[0002] Volatile organic compounds are various carbon-based chemicals with boiling points between 50℃ and 260℃ at atmospheric pressure (101.325 kPa). Most of them are toxic and harmful to human health. According to the chemical structure of organic matter, volatile organic compounds can be divided into alkanes, alkenes, alkynes, arenes, halogenated hydrocarbons, alcohols, aldehydes, ketones, esters and sulfur / nitrogen compounds. Volatile organic compounds come from indoor and outdoor emissions. The main sources of indoor volatile organic compounds include office supplies, insulation materials, cleaning products, building products and printed materials. Most outdoor volatile organic compounds come from industrial processes such as petrochemical, pharmaceutical, surface corrosion and automobile emissions, producing highly toxic and carcinogenic volatile organic compounds such as formaldehyde and benzene. Volatile organic compounds also damage the environment and are the main cause of stratospheric ozone depletion and photochemical smog formation. As the content of volatile organic compounds increases, the harm to human health and the ecological environment is increasing, so it is particularly important to control the flux of volatile organic compounds in the environment. Therefore, it is very important and urgent to use appropriate volatile organic compound removal technology. Absorption, condensation, membrane separation, thermal incineration, catalytic combustion, biological filtration and other technologies have been widely used in the control process of organic pollutants. Advanced catalytic oxidation technology can completely convert pollutants into carbon dioxide and water, which is a reliable and effective technology, and has received widespread attention in recent years and has great industrial application prospects. Photocatalysis and plasma technology have been successfully applied to the efficient treatment of volatile organic compounds. Patent 201810241723.9 uses a degradation filter layer to photocatalyze volatile organic compounds, producing free hydroxyl radicals and active oxygen with very strong oxidation ability, which has strong photo-oxidation and reduction functions and can oxidize and decompose various organic compounds and some inorganic compounds into non-polluting water (H2O) and carbon dioxide (CO2), but there is a problem of secondary pollution of intermediates such as ketones and aldehydes during the reaction. On the other hand, to further improve the oxidation, decomposition and decontamination performance of volatile organic compounds, the use of excess ultraviolet lamps produces a large amount of ozone, which erodes and damages the eyes, respiratory tract and lungs of the human body, and also pollutes the natural environment. Patent 201510291120.6 uses a compressed adsorption tank to adsorb VOCs, and its technical principle mainly includes steam heating and decomposing the adsorbent. However, most of the activated carbon will be caked during the steam decomposition process, and additional equipment is needed for drying, so the selection of adsorbent is a difficult problem. In addition, additional equipment is needed for condensation, which greatly increases the cost and has low economic efficiency, so this method cannot efficiently and losslessly treat VOCs. Therefore, a new method is urgently needed to efficiently degrade volatile organic compounds, recycle resources without producing carbon dioxide and produce high-value products, and achieve equipment simplification and low cost. SUMMARY

[0003] The application aims to provide a method for coupling hydrogen production with electro-catalytic oxidation of volatile organic pollutants into high-value products, and particularly relates to a novel coupling electro-catalytic method and a preparation scheme of a novel electrode material thereof.

[0004] One aspect of the application provides a method for coupling hydrogen production with electro-catalytic oxidation of volatile organic pollutants into high-value products.

[0005] The application is achieved by the following technical scheme:

[0006] 1. The application provides a method for coupling hydrogen production with electro-catalytic oxidation of volatile organic pollutants into high-value products, comprising: using a three-electrode system, i.e., a working electrode, a counter electrode and a reference electrode, to jointly form an electro-catalytic reactor. The working electrode is a porous nickel foam loaded nickel-iron oxide / hydroxide, wherein the metal oxide / hydroxide is nickel-iron oxide / hydroxide, and the preparation method comprises: (1) preparing a hydrogen peroxide reaction solution containing 3-10 mM Fe 2+ salt, and the mass fraction of the reaction solution is 1%-20%; (2) ultrasonically washing a foam metal with a thickness of 0.5 mm-3.0 mm with anhydrous ethanol, analytical pure acetone and deionized water for 20 min, and then immersing the foam metal in the above solution for reaction for 2-15 min; (3) after the reaction is completed, taking out the foam metal, washing the surface with deionized water, and drying at 60°C to obtain the porous nickel foam loaded metal oxide / hydroxide. The reference electrode is one of a saturated calomel electrode, Hg / HgO and Ag / AgCl, and the counter electrode is a platinum wire, a platinum sheet, a platinum mesh or a graphite carbon counter electrode. The catalytic oxidation is performed in an H-type electrolytic cell, and the scan speed of linear sweep voltammetry is 5 mV / s. Liquid volatile organic pollutants are added to an alkaline solution, the molar concentration of the reaction substrate volatile organic pollutants is 10-500 mM, the alkaline solution is a 0.1-2.0 M KOH or NaOH solution, and the reaction is performed at a constant potential voltage of 1.2-2.0 V for 2-3 h. After the reaction process is completed, high-value products can be obtained through simple separation.

[0007] 2. Preferably, the volatile organic pollutants are one of benzene, toluene, xylene, p-diethylbenzene, ethylene, propylene, 1,3-butadiene, chloroethylene, butadiene, trans-2-pentene, 1-pentene, methane, ethane, propane, ethylene oxide, 2-methylpentane, n-hexane, 2-methylheptane, 1,2-dichloroethane, chloromethane, butanol, ethylene glycol, methyl mercaptan, ethyl mercaptan, acetone and methyl ethyl ketone.

[0008] 3. Preferably, the thickness of the carrier of the catalyst in the working electrode is 0.5 mm-3.0 mm, and the size is (1-5) cm x (1-5) cm.

[0009] According to the application, the advanced oxidation technology is coupled with the electrocatalysis at the anode, the volatile organic pollutants can be degraded by compression condensation, the secondary pollution in the degradation process is avoided, the hydroxyl radicals can be generated by the electrocatalysis of the metal oxide / hydroxide working electrode loaded on the porous nickel foam, the organic pollutants can be efficiently and completely oxidized into high-value products, CO2 and H2O, and the hydrogen can be generated at the cathode.

[0010] Another aspect of the application provides a synthesis method of the porous nickel foam loaded metal oxide / hydroxide electrode material.

[0011] The application has the following advantages: 1, the high-value products synthesized by the application can be used as excellent raw materials or important intermediates for organic synthesis, and have high economic value; 2, the volatile organic pollutants such as formaldehyde, benzaldehyde and alcohol are dissolved in water, so that the primary pollution and secondary pollution in the degradation process are reduced, CO2 is not generated, the efficiency is high, the energy consumption is low, and the operation is simple; 3, the hydrogen is generated at the cathode, and a new energy is generated; 4, the organic pollutants harmful to the environment are removed by the electrocatalysis coupled with the advanced oxidation technology, the efficient removal of the organic waste gas is realized, and a new idea is provided for the environmental governance problem; 5, the target catalyst is in-situ grown on the porous nickel foam by the one-step solvothermal method, and the operation method is simple and efficient; 6, the catalyst has good stability and good catalytic effect, and is easy to recover; 7, the material is low in price, easy to obtain, high in synthesis yield and purity, simple in synthesis method, good in experimental repeatability, and suitable for the requirements of large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is the EDX image of the porous nickel foam loaded nickel, iron oxide / hydroxide working electrode in example 1 of the application.

[0013] Figure 2 is the SEM image of the porous nickel foam loaded nickel, iron oxide / hydroxide working electrode in example 1 of the application.

[0014] Figure 3 is the linear sweep voltammetry curve of the benzyl alcohol electrocatalysis process in example 2 of the application.

[0015] Figure 4 is the linear sweep voltammetry curve of the benzylamine electrocatalysis process in example 3 of the application.

[0016] Figure 5 is the linear sweep voltammetry curve of the n-propyl alcohol electrocatalysis process in example 4 of the application. DETAILED DESCRIPTION

[0017] The application will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the application are not limited thereto.

[0018] Example 1

[0019] A reaction solution 50 mL containing 3 mM of ferrous chloride and 5% of hydrogen peroxide by mass was prepared, and then a porous nickel foam with a thickness of 1.0 mm and a size of 2 cm x 2 cm was ultrasonically washed with anhydrous ethanol, analytical pure acetone and deionized water for 20 min, and then immersed in the above solution for reaction for 15 min. After the reaction was completed, it was taken out, the surface was washed clean with deionized water, and was dried at 60°C to prepare a porous nickel foam loaded nickel, iron oxide / hydroxide.

[0020] A three-electrode system was used to perform catalytic oxidation in an H-type electrolytic cell. The porous nickel foam loaded nickel, iron oxide / hydroxide was used as a working electrode, Hg / HgO was used as a reference electrode, and a platinum wire was used as a counter electrode to form an electrocatalytic reactor.

[0021] In the cathode electrolysis chamber, 0.5 M NaOH solution was used as a cathode electrolyte, and in the anode electrolysis chamber, 50 mM benzaldehyde was dissolved in 0.5 M NaOH solution as an anode electrolyte, and magnetic stirring was performed.

[0022] The reaction was continuously stirred at a constant voltage of 1.4 V for 2 h. After the reaction was completed, the product was precipitated in the lower layer of the solution, and the reaction product was detected by high performance liquid chromatography. The yield of m-nitrobenzaldehyde was 86%.

[0023] Example 2

[0024] A reaction solution 50 mL containing 3 mM of ferrous chloride and 5% of hydrogen peroxide by mass was prepared, and then a porous nickel foam with a thickness of 1.0 mm and a size of 2 cm x 2 cm was ultrasonically washed with anhydrous ethanol, analytical pure acetone and deionized water for 20 min, and then immersed in the above solution for reaction for 15 min. After the reaction was completed, it was taken out, the surface was washed clean with deionized water, and was dried at 60°C to prepare a porous nickel foam loaded nickel, iron oxide / hydroxide.

[0025] A three-electrode system was used to perform catalytic oxidation in an H-type electrolytic cell. The porous nickel foam loaded nickel, iron oxide / hydroxide was used as a working electrode, Hg / HgO was used as a reference electrode, and a platinum wire was used as a counter electrode to form an electrocatalytic reactor.

[0026] In the cathode electrolysis chamber, 0.5 M NaOH solution was used as a cathode electrolyte, and in the anode electrolysis chamber, 50 mM benzaldehyde was dissolved in 0.5 M NaOH solution as an anode electrolyte, and magnetic stirring was performed.

[0027] The reaction was continuously stirred at a constant voltage of 1.5 V for 3 h. After the reaction was completed, the reaction product was detected by high performance liquid chromatography, and the yield of benzoic acid was 90%.

[0028] Example 3

[0029] A reaction solution containing 3 mM of ferrous sulfate and 5% hydrogen peroxide by mass was prepared in an amount of 50 mL. Then, a foamed nickel with a thickness of 1 mm and a size of 1.5 cm x 1.5 cm was ultrasonically washed with anhydrous ethanol, analytical pure acetone, and deionized water for 20 min each, and then immersed in the above solution for reaction for 15 min. After the reaction was completed, it was taken out, the surface was washed with deionized water, and dried at 60°C to obtain a porous foamed nickel supported nickel, iron oxide / hydroxide.

[0030] A three-electrode system was used to perform catalytic oxidation in an H-type electrolytic cell. The porous foamed nickel supported nickel, iron oxide / hydroxide was used as the working electrode, Hg / HgO was used as the reference electrode, and platinum wire was used as the counter electrode to form an electrocatalytic reactor.

[0031] In the cathode electrolysis chamber, 1M KOH solution was used as the cathode electrolyte, and in the anode electrolysis chamber, 100mM n-propylamine was dissolved in 1M KOH solution as the anode electrolyte, and magnetic stirring was performed.

[0032] The reaction was continuously stirred at a constant voltage of 1.5 V for 3 h. After the reaction was completed, the reaction product was detected by high performance liquid chromatography, and the yield of benzoic acid was 90%.

[0033] Example 4

[0034] A reaction solution containing 3 mM of ferrous sulfate and 5% hydrogen peroxide by mass was prepared in an amount of 50 mL. Then, a foamed nickel with a thickness of 1 mm and a size of 1.5 cm x 1.5 cm was ultrasonically washed with anhydrous ethanol, analytical pure acetone, and deionized water for 20 min each, and then immersed in the above solution for reaction for 15 min. After the reaction was completed, it was taken out, the surface was washed with deionized water, and dried at 60°C to obtain a porous foamed nickel supported nickel, iron oxide / hydroxide.

[0035] A three-electrode system was used to perform catalytic oxidation in an H-type electrolytic cell. The porous foamed nickel supported nickel, iron oxide / hydroxide was used as the working electrode, Hg / HgO was used as the reference electrode, and platinum wire was used as the counter electrode to form an electrocatalytic reactor.

[0036] In the cathode electrolysis chamber, 1M KOH solution was used as the cathode electrolyte, and in the anode electrolysis chamber, 100mM n-propylamine was dissolved in 1M KOH solution as the anode electrolyte, and magnetic stirring was performed.

[0037] The reaction was continuously stirred at a constant voltage of 1.5 V for 2.5 h. After the reaction was completed, the reaction product was detected by high performance liquid chromatography, and the yield of propionic acid was 89%.

[0038] Example 5

[0039] A reaction solution containing 3 mM ferrous chloride and 5% hydrogen peroxide by mass was prepared in an amount of 50 mL. Foam nickel with a thickness of 0.5 mm and a size of 1 cm x 1 cm was ultrasonically washed with anhydrous ethanol, analytical pure acetone and deionized water for 20 min, and then immersed in the above solution for reaction for 15 min. After the reaction was completed, the foam nickel was taken out, the surface was washed with deionized water, and was dried at 60°C to obtain porous foam nickel loaded with nickel and iron oxide / hydroxide.

[0040] The catalytic oxidation was carried out in an H-type electrolytic cell using a three-electrode system. The porous foam nickel loaded with nickel and iron oxide / hydroxide was used as the working electrode, Hg / HgO was used as the reference electrode, and platinum wire was used as the counter electrode to form an electrocatalytic reactor.

[0041] In the cathode electrolysis chamber, 1M KOH solution was used as the cathode electrolyte, and in the anode electrolysis chamber, 100 mM isopropyl alcohol was dissolved in 1M KOH solution as the anode electrolyte, and magnetic stirring was carried out.

[0042] The reaction was continuously stirred at a constant voltage of 1.5 V for 2 h. After the reaction was completed, the reaction product was detected by high performance liquid chromatography, and the yield of acetone was 95%.

[0043] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for electrocatalytic oxidation of volatile organic pollutants into high-value products coupled with hydrogen production, characterized in that: Volatile organic pollutants are compressed by the compressor and then enter the condenser, where the organic vapors are converted from a gaseous state to a liquid state. Finally, they enter the electrocatalytic system, which adopts a three-electrode system. The reference electrode is one of a saturated calomel electrode, Hg / HgO, or Ag / AgCl. The working electrode is a metal oxide / hydroxide supported on porous nickel foam, wherein the metal oxide / hydroxide is nickel-iron oxide / hydroxide. The preparation method of metal oxide / hydroxide supported on porous nickel foam in the working electrode includes the following steps: the size of the catalyst support in the working electrode is (1-5) cm × (1-5) cm; (1) Preparation of Fe containing 3~10 mmol / L 2+ The hydrogen peroxide reaction solution for salt has a mass fraction of 1% to 20%. (2) Wash the foam metal with a thickness of 0.5 mm to 1.0 mm with anhydrous ethanol, analytical grade acetone and deionized water by ultrasonication for 20 min each, and then soak it in the above solutions for 2 to 15 min. (3) After the reaction is complete, remove it, rinse the surface with deionized water, and dry it at 60°C to prepare porous nickel foam loaded metal oxide / hydroxide; the counter electrode is a platinum wire, platinum sheet, platinum mesh or graphite carbon counter electrode; the constant voltage range is 1.2 to 2.0 V, add 0.1 to 2.0 M alkaline electrolyte to the anode chamber and the cathode chamber respectively, and then add liquid volatile organic pollutants to the anode electrolyte. Electrochemical oxidation of organic pollutants coupled to the cathode to produce hydrogen is carried out by passing electricity. After the electrolysis is completed, the product is separated by the anode.

2. The method for electrocatalytic oxidation of volatile organic pollutants into high-value products coupled with hydrogen production according to claim 1, characterized in that, The volatile organic pollutant is one of the following: benzene, toluene, xylene, p-diethylbenzene, ethylene, propylene, 1,3-butadiene, vinyl chloride, butadiene, trans-2-pentene, 1-pentene, methane, ethane, propane, ethylene oxide, 2-methylpentane, n-hexane, 2-methylheptane, 1,2-dichloroethane, chloromethane, butanol, ethylene glycol, methanethiol, ethyl mercaptan, acetone, and methyl ethyl ketone.

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