CN113089002A - Selective oxidation device and method for coupling organic matters through electrocatalysis hydrogen peroxide production - Google Patents

Abstract

Hair brushThe reaction device consists of an anode chamber, a cathode chamber and an organic catalysis chamber, wherein the cathode chamber contains a catalyst for preparing hydrogen peroxide by oxygen reduction, the anode chamber contains a catalyst for water oxidation or hydrogen oxidation, the organic catalysis chamber contains an organic oxidation catalyst, the anode chamber and the organic catalysis chamber are separated by a cation exchange membrane, and the cathode chamber and the organic catalysis chamber are separated by an anion exchange membrane; when the reactor works, oxygen or air is introduced into the cathode chamber, hydrogen or water is introduced into the anode, and an organic reactant is introduced into the organic catalytic chamber; under the electrified condition, the cathode is reduced by oxygen to obtain OOH^‑The anode is subjected to water oxidation or hydrogen oxidation reaction to obtain H⁺H is formed by entering the middle organic catalytic chamber through corresponding anion-cation exchange membranes₂O₂Further oxidizing the organic matter under the action of the catalyst. The invention directly uses the low-concentration hydrogen peroxide generated by oxygen reduction for organic matter oxidation, thereby avoiding H₂O₂The separation, concentration, storage and transportation costs and the safety problem of the method have obvious economic benefits. When the catalyst is used for phenol oxidation, benzyl alcohol oxidation, furfuryl alcohol oxidation and cyclohexanone conversion, the selectivity of target products of benzenediol, benzaldehyde, furfural and cyclohexanone oxime is more than 98%, and the corresponding total current efficiency is 21-49%.

Description

Selective oxidation device and method for coupling organic matters through electrocatalysis hydrogen peroxide production

Technical Field

The invention belongs to the field of electrochemical organic synthesis, and particularly relates to a device and a method for coupling selective oxidation of organic matters by electrocatalysis to produce hydrogen peroxide.

Background

The hydrogen peroxide is a commonly used chemical agent, is a well-known efficient, green and environment-friendly oxidant, and is widely applied to the fields of selective oxidation of organic matters, wastewater treatment, sanitation and disinfection and the like. In industry, hydrogen peroxide is almost completely produced by an anthraquinone redox method, and although the method has the advantages of mature technology, high one-way yield, high safety and the like, the method still has the problems of high investment, complex process flow, and product pollution and environmental pollution caused by using a large amount of organic solvents. Compared with the anthraquinone method, the method takes oxygen as a raw material and electric energy as drive to synthesize the hydrogen peroxide, does not need to introduce other solvents, does not discharge harmful substances, and meets the requirements of green chemical industry better.

However, the reaction current density of electrocatalytic oxygen reduction is usually small, the concentration of the generated hydrogen peroxide is low, and further concentration is needed to prepare the product. In addition, there is a certain risk in storage and transportation of hydrogen peroxide. If the low-concentration hydrogen peroxide generated by oxygen reduction can be applied to selective oxidation of organic matters in situ, namely the generated hydrogen peroxide is immediately combined by the catalyst and reacts with organic raw materials, the problems of separation, concentration, transportation, storage and the like of the hydrogen peroxide can be avoided, the safety is improved, and the cost is reduced.

Disclosure of Invention

The invention provides a device and a method for coupling electrocatalytic hydrogen peroxide production with selective oxidation of organic matters, and a high-value-added organic product continuously produced by using the device and the method.

An apparatus for electrocatalytic hydrogen peroxide generation coupled with selective oxidation of organic matter comprises: a cathode chamber (1), an anode chamber (2) and an organic catalytic chamber (3); liquid phase inlets and outlets are arranged at two ends of the organic catalysis chamber; the organic catalytic chamber is positioned between the cathode chamber and the anode chamber; the cathode chamber and the organic catalyst chamber are separated by an anion exchange membrane (4), and the anode chamber and the organic catalyst chamber are separated by a cation exchange membrane (5).

The cathode chamber consists of a collector plate (10), a gas diffusion layer (6) and a catalyst layer (7), and is provided with an oxygen or air inlet, an oxygen or air outlet and a flow passage.

The anode chamber consists of a collector plate (11), a gas diffusion layer (8) and a catalyst layer (9), and is provided with a water or hydrogen inlet, a water or hydrogen outlet and corresponding flow channels.

The organic catalysis chamber is filled with Solid Electrolyte (SE) and catalyst filler, wherein the solid electrolyte is styrene-divinylbenzene copolymer microspheres (Na)⁺Form (A) or (H)⁺Type), Al₂O₃One or more of polyacrylonitrile, polyvinylidene fluoride, polypropylene oxide, oxygen ion conductor and fluorine ion conductor.

The invention also provides a method for coupling selective oxidation of organic matters by electrocatalysis hydrogen peroxide production, which is characterized by comprising the following steps: the humidified oxygen or air is introduced into the cathode chamber (1) at a certain flow rate, and the humidified hydrogen or water is introduced into the anode chamber (2) at a certain flow rate. When electrified, under a certain system temperature, oxygen or air in the cathode chamber generates oxygen reduction reaction under the action of a catalyst to generate OOH^-(ii) a Hydrogen oxidation or water oxidation to H in anode chamber under corresponding catalyst⁺(ii) a H is formed in the organic catalytic chamber (3) through corresponding anion and cation exchange membranes (4, 5) respectively₂O₂. Introducing organic water solution with certain concentration into the organic catalytic chamber (3) at a certain flow rate, and catalyzing the H under the action of a catalyst₂O₂Selectively oxidizing the organic matter to obtain the target product and extracting.

The current density is 10-500 mA/cm²The system temperature is 10-70 ℃, the concentration of the organic matter aqueous solution is 0.05-1M, and the loading capacity of the cathode catalyst and the anode catalyst is 0.1-1 mg/cm²The filling amount of the catalyst in the organic catalysis chamber is 10-200 mg/cm³。

The oxygen reduction catalyst is any one of M-N-C (M ═ Co, Fe and Mn), O-CNTs, Au-Pd, Pd-Hg, M-CNT (M ═ Fe and Co), O-CNTs, GO and functionalized carbon powder, and preferably the functionalized carbon powder; the Hydrogen Oxidation (HOR) catalyst is Pt/C, Pt-CeO₂、Rh-Rh₂O₃PdNi, PdCu, MOF (Ni-BTC), preferably Pt/C, the water Oxidation (OER) catalyst being NiCoO_x、CoFeO_x、IrO_x/SrIrO₃、IrO₂、RuO₂、FeCoW、NiO_x、NiFeO_xPreferably porous IrO₂and/C. The preparation method of the functionalized carbon powder catalyst comprises the following steps:

and S1, functionalizing the carbon powder. Weighing 200mg of commercially available carbon powder in a 500mL round-bottom flask, adding 200mL of concentrated nitric acid, heating to reflux to 85 ℃, timing, reacting for 12 hours, cooling to room temperature, adding water for dilution, performing suction filtration and washing to neutrality, drying, performing ball milling to obtain powder, and finally annealing in air at 300 ℃ for 2 hours to obtain functionalized carbon powder;

the organic catalyst is any one or more of titanium silicalite molecular sieve (TS-1), Beta molecular sieve, NC (COF, MOF) catalyst, Amberlyst-150 and catalyst obtained by modifying molecular sieve by using metals such as Cu, Sn, Co, Fe and the like.

The invention has the beneficial effects that:

(1) the invention provides a device and a process for directly applying hydrogen peroxide prepared by electrocatalytic oxygen reduction to selective oxidation of organic matters in situ, which couple electrochemical generation of hydrogen peroxide and oxidation of the organic matters in the same device, avoid separation, purification, transportation, storage and dilution of the hydrogen peroxide, solve the safety problem caused by instability of the hydrogen peroxide, and reduce equipment investment and operation cost.

(2) The device and the process provided by the invention have universality, can be coupled with various organic raw materials to synthesize high-added-value products (such as benzaldehyde, cyclohexanone oxime, benzenediol, maleic acid, epoxy styrene and the like), and have wide industrial application prospects.

Drawings

FIG. 1 is a schematic diagram of an apparatus for electrochemical generation of hydrogen peroxide coupled with selective oxidation of organic compounds according to the present invention.

1-cathode chamber; 2-anode chamber; 3-organic catalytic chamber; 4-an anion exchange membrane; 5-cation exchange membrane; 6, 8-diffusion layer; 7, 9-catalytic layer; 10, 11-current collecting plate.

Detailed Description

The invention aims to provide a device and a method for coupling selective oxidation of organic matters by electrocatalysis to generate hydrogen peroxide. The present invention will be described in detail with reference to the following examples and drawings, it should be understood that the examples and drawings are only illustrative of the present invention and are not intended to limit the scope of the present invention in any way, and all reasonable variations and combinations included within the spirit of the present invention fall within the scope of the present invention.

As shown in fig. 1, an apparatus for electrochemical generation of hydrogen peroxide coupled with selective oxidation of organic compounds comprises:

for generating OOH by oxygen reduction^-A cathode chamber (1). The cathode chamber consists of a collector plate (10), a gas diffusion layer (6), a catalyst layer (7), a gas inlet and outlet channel and a flow channel. Wherein the catalyst layer is a catalyst for producing hydrogen peroxide by oxygen reduction, and is preferably a functionalized carbon powder catalyst.

For producing H by hydrogen oxidation or water oxidation⁺And an anode chamber (2). The anode chamber consists of a collector plate (11), a gas diffusion layer (8), a catalyst layer (9), a gas/liquid inlet/outlet channel and a flow channel. Wherein the catalyst layer is a hydrogen oxidation or water oxidation catalyst, preferably corresponding Pt/C or IrO₂a/C catalyst.

An organic catalytic chamber (3) for catalyzing the selective oxidation of hydrogen peroxide.The organic catalytic chamber consists of a Solid Electrolyte (SE) and a catalyst filler layer, wherein the solid electrolyte is styrene-divinylbenzene copolymer microspheres (Na)⁺Form (A) or (H)⁺Type), Beta-Al₂O₃One or more of polyacrylonitrile, polyvinylidene fluoride, polypropylene oxide, oxygen ion conductor and fluorine ion conductor; the catalyst for catalyzing hydrogen peroxide to selectively oxidize organic matters is any one or more of a titanium silicalite molecular sieve (TS-1), a Beta molecular sieve, an NC (COF, MOF) catalyst, Amberlyst-150 and a catalyst obtained by modifying the molecular sieve by utilizing metals such as Cu, Sn, Co, Fe and the like.

An anion membrane (4) for separating the cathode chamber (1) and the organic catalyst chamber (3).

A cation membrane (5) for separating the anode chamber (2) and the organic catalyst chamber (3).

According to one embodiment of the present invention, phenol is selectively oxidized to prepare benzenediol, benzyl alcohol to prepare benzaldehyde, furfuryl alcohol to prepare furfural, and cyclohexanone is selectively oxidized to prepare cyclohexanone oxime in a reaction device shown in FIG. 1. The humidified oxygen or air is introduced into the cathode chamber (1) at a certain flow rate, and the humidified hydrogen or water is introduced into the anode chamber (2) at a certain flow rate. When electrified, under a certain system temperature, oxygen or air in the cathode chamber generates oxygen reduction reaction under the action of a catalyst to generate OOH^-(ii) a Hydrogen oxidation or water oxidation to H in anode chamber under corresponding catalyst⁺(ii) a H is formed in the organic catalytic chamber (3) through corresponding anion and cation exchange membranes (4, 5) respectively₂O₂. Introducing organic water solution with certain concentration into the organic catalytic chamber (3) at a certain flow rate, and catalyzing the H under the action of a catalyst₂O₂Selectively oxidizing the organic matter to obtain the target product and extracting.

The present invention will be further described with reference to specific embodiments.

Example 1

Adopting air and hydrogen system, the anode and cathode are 0.5mg/cm respectively²Functionalized carbon powder and commercial Pt/C, the effective area of the catalyst is 4cm²The organic oxidation catalyst was 0.1g of TS-1 molecular sieve. 0.1M K₂SO₄The aqueous solution is introduced into the organic catalyst by a peristaltic pumpThe chamber was cycled at a flow rate of 0.18ml/min and was powered on at a current density of 37.5mA/cm²Carrying out constant current electrolysis, collecting the solution, and titrating the concentration of hydrogen peroxide by using potassium iodide after the system is activated for 30 min; mixing organic raw material (containing 0.085M phenol and 0.1M K M)₂SO₄) The aqueous solution is introduced into an organic catalytic chamber through a peristaltic pump, the total volume of the solution is 20ml, and the flow rate is 0.18 ml/min; at a current density of 37.5mA/cm²When the electrolysis is carried out at the room temperature under constant current, the voltage of the cell is about 0.8V, the electrolysis is carried out for 2h in a circulating way, the electrolysis circulation is stopped for 8h, the electricity is interrupted in the circulating process, the hydrogen peroxide is continuously produced, the phenol is selectively oxidized, and the residual hydrogen peroxide in the previous 2h is consumed. The conversion of phenol was about 37.04%, the selectivity of hydroquinone was 97.88%, the ratio of catechol to hydroquinone was 0.83, and the current efficiency was 11.26%.

Example 2

This embodiment is substantially the same asembodiment 1 except that: the starting phenol concentration was expanded to 0.262M. After stabilization by activation, 20ml of a solution containing 0.262M phenol, 0.1M K₂SO₄The aqueous solution is introduced into the organic catalytic chamber by a peristaltic pump at a current density of 37.5mA/cm²The solution is electrolyzed for 2h in a circulation mode under constant current, the voltage of the cell is about 0.85V, and then the circulation is interrupted for 8 h. The conversion of phenol was about 18.25%, the selectivity of hydroquinone was 94.81%, the ratio of catechol to hydroquinone was 0.73, and the current efficiency was 17.09%.

Example 3

This embodiment is substantially the same asembodiment 1 except that: the starting phenol concentration was expanded to 0.506M. After stabilization by activation, 20ml of a solution containing 0.506M phenol, 0.1M K₂SO₄The aqueous solution is introduced into the organic catalytic chamber by a peristaltic pump at a current density of 37.5mA/cm²The solution is electrolyzed for 2h in a circulation mode under constant current, the voltage of the cell is about 0.9V, and then the circulation is interrupted for 8 h. The conversion rate of phenol is about 11.98%, the selectivity of benzenediol is 94.89%, the ratio of catechol to hydroquinone is 0.69, and the current efficiency is 21.69%.

Example 4

This embodiment is substantially the same asembodiment 1 except that: the starting phenol concentration was expanded to 0.795M. After stabilization by activation, 20ml of a solution containing 0.795M phenol, 0.1M K₂SO₄The aqueous solution is introduced into the organic catalytic chamber by a peristaltic pump at a current density of 37.5mA/cm²The solution is electrolyzed for 2h in a circulation mode under constant current, the voltage of the cell is about 0.95V, and then the circulation is interrupted for 8 h. The conversion rate of phenol is about 10.65%, the selectivity of benzenediol is 95.58%, the ratio of catechol to hydroquinone is 0.69, and the current efficiency is 30.25%.

Example 5

This embodiment is substantially the same asembodiment 1 except that: the starting phenol concentration was expanded to 1.065M. After stabilization of the activation, 20ml of a solution containing 1.065M phenol, 0.1M K₂SO₄The aqueous solution is introduced into the organic catalytic chamber by a peristaltic pump at a current density of 37.5mA/cm²The solution is electrolyzed for 2h in a circulation mode under constant current, the voltage of the cell is about 1.1V, and then the circulation is interrupted for 8 h. The conversion of phenol was about 5.17%, the selectivity of hydroquinone was 95.67%, the ratio of catechol to hydroquinone was 0.63, and the current efficiency was 19.69%.

For the sake of comparative illustration, the substrate concentrations and results in each example are shown in Table 1:

TABLE 1 influence of phenol concentration on the reaction results

[ note)]The current density is 37.5mA/cm²。

Example 6

This embodiment is substantially the same asembodiment 1 except that: the concentration of phenol as a raw material was increased to 74.7mg/ml, and the current density was adjusted to 25mA/cm². After stabilization of the activation at this current density, 20ml of a solution containing 74.7mg/ml phenol, 0.1M K₂SO₄The aqueous solution is introduced into the organic catalytic chamber by a peristaltic pump at a current density of 25mA/cm²The solution is electrolyzed circularly with constant current, the voltage of the cell is about 0.85V, and the sampling test is carried out after 2h of electrolysis and 8h of power-off circulation. The conversion of phenol was about 5.24%, the selectivity to hydroquinone was 76.12%, the ratio of catechol to hydroquinone was 1.46, and the current efficiency was 22.43%.

Example 7

This embodiment is substantially the same asembodiment 1 except that: the concentration of phenol as a raw material was increased to 74.7mg/ml, and the current density was adjusted to 50mA/cm². After stabilization of the activation at this current density, 20ml of a solution containing 74.7mg/ml phenol, 0.1M K₂SO₄The aqueous solution is introduced into the organic catalytic chamber through a peristaltic pump at a current density of 50mA/cm²The solution is electrolyzed circularly under constant current, the voltage of the cell is about 1.1-1.3V, and the sampling test is carried out after 2h of electrolysis and 8h of power-off circulation. The conversion of phenol was about 5.32%, the selectivity to hydroquinone was 81.81%, the ratio of catechol to hydroquinone was 0.797, and the current efficiency was 11.41%.

For the sake of comparative illustration, only the current density variations and the results in each example are shown in Table 2:

TABLE 2 Effect of Current Density on reaction results

[ Note ] the substrate phenol concentrations were all 74.7 mg/ml.

Example 8

This example is substantially the same as example 4, except that: the temperature was adjusted to 40 ℃. And after 2 hours of electrolysis, performing power-off cycle for 8 hours for sampling test. The conversion of phenol was about 7.83%, the selectivity of hydroquinone was 73.93%, the ratio of catechol to hydroquinone was 1.18, and the current efficiency was 22.34%.

Example 9

This example is substantially the same as example 4, except that: the temperature was adjusted to 50 ℃. And after 2 hours of electrolysis, performing power-off cycle for 8 hours for sampling test. The conversion of phenol was about 6.08%, the selectivity of hydroquinone was 74.61%, the ratio of catechol to hydroquinone was 1, and the current efficiency was 17.34%.

For the sake of comparative illustration, only the temperature changes and the results in each example are shown in Table 3:

TABLE 3 influence of temperature on the reaction results

[ Note ] the substrate phenol concentration was 74.7mg/ml, and the current density was 37.5mA/cm 2.

Example 10

This embodiment is substantially the same asembodiment 1 except that: the substrate is 0.1M benzyl alcohol, 0.1M K₂SO₄And the reaction is carried out for 1.5h under the electrolysis condition without subsequent power-off circulation, the conversion rate of the benzyl alcohol is 12.74%, the selectivity of the benzaldehyde is more than 95%, and the current efficiency is 21.53%.

Example 11

This embodiment is substantially the same asembodiment 1 except that: the substrate was 0.1M styrene, 0.1M K₂SO₄0.1g of titanium silicalite molecular sieve (TS-1), generating benzaldehyde and epoxy styrene after electrolysis for 1.5h, wherein the conversion rate of the styrene is 16.21%, and the total selectivity of the benzaldehyde and the styrene oxide is 80.63%.

Example 12

This embodiment is substantially the same asembodiment 1 except that: the substrate is 0.1M furfuryl alcohol, 0.1M K₂SO₄0.1g of titanium silicalite molecular sieve (TS-1) or 0.1g of ZIF-8, wherein furfural is generated after electrolysis for 1.5h, the conversion rate of furfuryl alcohol is 20.54%, and the selectivity of furfural is 60.86%.

Example 13

This embodiment is substantially the same asembodiment 1 except that: the middle organic chamber only has solid electrolyte and no organic catalyst filler layer, and no supporting electrolyte is added in the reaction process. In addition, a heatable magnetic stirrer is arranged outside the outlet section of the organic catalytic chamber, meanwhile, a hydrogen peroxide collector is arranged on the magnetic stirrer, when 20ml of hydrogen peroxide solution is collected, 0.1M cyclohexanone and ammonia water are added into the hydrogen peroxide solution, the temperature is raised to 50 ℃, the continuous reaction is carried out for 1.5h, the conversion rate of the cyclohexanone is about 98.82%, the selectivity of the cyclohexanone oxime is 100%, and the current efficiency is 47.08%.

For the purpose of comparative illustration, the reaction conditions and results of the different substrates in each example are shown in Table 4:

table 4 results of different substrate experiments

Claims (8)

1. The device for coupling the electrocatalytic production of hydrogen peroxide with the selective oxidation of organic matters is characterized by comprising a cathode chamber (1), an anode chamber (2) and an organic catalytic chamber (3); liquid phase inlets and outlets are arranged at two ends of the organic catalysis chamber; the organic catalytic chamber is positioned between the cathode chamber and the anode chamber; the cathode chamber and the organic catalyst chamber are separated by an anion exchange membrane (4), and the anode chamber and the organic catalyst chamber are separated by a cation exchange membrane (5).

2. Device according to claim 1, characterized in that the cathode compartment consists of collector plate (10), gas diffusion layer (6), catalytic layer (7) and is provided with oxygen or air inlet, outlet and flow channels.

3. The device according to claim 1, characterized in that the anode chamber consists of a collector plate (11), a gas diffusion layer (8), a catalytic layer (9) and is provided with a hydrogen or water inlet, outlet and corresponding flow channels.

4. The apparatus of claim 1, wherein the organic catalyst chamber is filled with a Solid Electrolyte (SE) and a catalyst filler, wherein the solid electrolyte is styrene-divinylbenzene copolymer microspheres (Na)⁺Form (A) or (H)⁺Type), Al₂O₃One or more of polyacrylonitrile, polyvinylidene fluoride, polypropylene oxide, oxygen ion conductor and fluorine ion conductor.

5. A method for coupling selective oxidation of organic matters by electrocatalysis hydrogen peroxide generation is characterized in that the method comprises the following steps: the humidified oxygen or air is introduced into the cathode chamber (1) at a certain flow rate, and the humidified hydrogen or water is introduced into the anode chamber (2) at a certain flow rate. When electrified, at a certain system temperatureOxygen or air in the cathode chamber is subjected to oxygen reduction reaction under the action of a catalyst to generate OOH^-(ii) a Hydrogen oxidation or water oxidation to H in anode chamber under corresponding catalyst⁺(ii) a H is formed in the organic catalytic chamber (3) through corresponding anion and cation exchange membranes (4, 5) respectively₂O₂. Introducing organic water solution with certain concentration into the organic catalytic chamber (3) at a certain flow rate, and catalyzing the H under the action of a catalyst₂O₂Selectively oxidizing the organic matter to obtain the target product and extracting.

6. The method of claim 5, wherein the current density is 10 to 500mA/cm²The system temperature is 10-70 ℃, the concentration of the organic matter aqueous solution is 0.05-1M, and the loading capacity of the cathode catalyst and the anode catalyst is 0.1-1 mg/cm²The filling amount of the catalyst in the organic catalysis chamber is 10-200 mg/cm³。

7. The method of claim 5, wherein the oxygen reduction catalyst is any one of M-N-C (M ═ Co, Fe, Mn), O-CNTs, Au-Pd, Pd-Hg, M-CNT (M ═ Fe, Co), O-CNTs, GO, functionalized carbon powder, preferably functionalized carbon powder; the hydrogen Hydroxide (HOR) catalyst is Pt/C, Pt-CeO2 and Rh-Rh₂O₃PdNi, PdCu, MOF (Ni-BTC), preferably Pt/C, the water Oxidation (OER) catalyst being NiCoO_x、CoFeO_x、IrOx/SrIrO₃、IrO₂、RuO₂、FeCoW、NiO_x、NiFeO_xPreferably porous IrO₂and/C. The preparation method of the functionalized carbon powder catalyst comprises the following steps:

and S1, functionalizing the carbon powder. Weighing 200mg of commercially available carbon powder in a 500ml round-bottom flask, adding 200ml of concentrated nitric acid, heating and refluxing to 85 ℃, timing, reacting for 12 hours, cooling to room temperature, adding water for dilution, performing suction filtration and washing to be neutral, drying, performing ball milling to obtain powder, and finally annealing in air at 300 ℃ for 2 hours to obtain the functionalized carbon powder.

8. The method of claim 5, wherein the organic catalyst chamber catalyst is any one or more of titanium silicalite (TS-1), Beta molecular sieve, NC (COF, MOF) catalyst, Amberlyst-150, and catalyst obtained by modifying molecular sieve with Cu, Sn, Co, Fe, etc.

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