Alkane oxidation method and reaction device

Abstract

An alkane oxidation method and a reaction device. The method comprises: providing an electrolytic cell, wherein the electrolytic cell is filled with an electrolyte solution, a first electrode (20) and a second electrode (30) are provided in the electrolyte solution, the electrolyte solution contains an acidic material, the material of the first electrode (20) comprises copper, and the material of the second electrode (30) comprises copper; and connecting a power supply between the first electrode and the second electrode, and introducing an alkane and an oxidizing agent into the electrolyte solution to oxidize the alkane. The method can be used for preparing a high value-added chemical product by means of alkane activation at room temperature under atmospheric pressure and has the characteristics of requiring low cost, being simple, etc.

Description

Alkane oxidation method and reaction device

[0001] Related applications

[0002] This application claims the Chinese patent application number 202410082559.7 filed on January 19, 2024, entitled “Method and reaction device for oxidation of alkanes”, the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of chemical technology, and in particular to an alkane oxidation method and a reaction device. Background Art

[0004] The direct activation of hydrocarbon alkanes into high-value-added chemical products such as alkenes, alkynes and their oxygen-containing derivatives has important economic value. However, due to factors such as the poor polarity and high bond energy of carbon-hydrogen bonds, high-energy consumption and high-carbon emission equipment are usually required to provide extreme reaction conditions such as high temperature and high pressure to achieve this process. In addition, providing an external potential is also a way to change the energy of the system, and the reaction conditions are milder and the production cost is lower. However, in traditional technologies, the conversion of alkanes into high-value-added chemicals uses precious metals as working electrodes, which are extremely expensive and need to be carried out at high temperature and high pressure. Therefore, the development of high-performance and stable catalysts and corresponding reaction systems to achieve efficient electrochemical activation of alkanes to synthesize high-value-added chemical products under normal temperature and pressure conditions still faces many problems and challenges.

[0005] Summary of the Invention

[0006] In a first aspect, the present application provides a method for oxidizing an alkane, comprising:

[0007] Providing an electrolytic cell, comprising an electrolyte, and a first electrode and a second electrode disposed in the electrolyte, wherein the electrolyte contains an acidic material, the material of the first electrode comprises copper, and the material of the second electrode comprises copper; and

[0008] A power source is connected between the first electrode and the second electrode, and an alkane and an oxidant are introduced into the electrolyte to oxidize the alkane.

[0009] In some embodiments, the acidic material includes at least one of sulfuric acid, perchloric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, and hydroiodic acid.

[0010] In some embodiments, the hydrogen ion concentration in the electrolyte is 1×10 -7 mol / L~2.0mol / L.

[0011] In some embodiments, the electrolyte further contains a copper salt.

[0012] In some embodiments, the copper salt includes at least one of Cu(ClO4)2, CuSO4, and CuCl2.

[0013] In some embodiments, the molar concentration of the copper salt in the electrolyte is 0.05 mol / L to 0.8 mol / L.

[0014] In some embodiments, the alkane includes at least one of a chain alkane and a cyclic alkane.

[0015] In some embodiments, the product after oxidation of the alkane includes at least one of olefins, alkynes, alcohol compounds, carboxylic acid compounds, ketone compounds, aldehyde compounds, ester compounds, phenol compounds and ether compounds.

[0016] In some embodiments, the oxidant comprises at least one of an organic peroxide, ozone, hydrogen peroxide, oxygen, and air.

[0017] In some embodiments, based on the total volume of the alkane and the oxidant being 100%, the volume proportion of the oxidant is 5% to 50%.

[0018] In some embodiments, the electrolytic cell further comprises a reference electrode, and the method further comprises controlling the voltage between the working electrode and the reference electrode to be a constant voltage.

[0019] In some embodiments, the voltage of the working electrode is 0.4 V to 1.4 V relative to a standard hydrogen electrode.

[0020] In some embodiments, the oxidation temperature in the method is 10° C. to 40° C., and the pressure is 0.5 atm to 1.5 atm.

[0021] In some embodiments, the alkane and the oxidant are introduced into the electrolyte in the form of a mixed gas, and the flow rate of the mixed gas is 1 mL / min to 15 mL / min.

[0022] In some embodiments, the method further includes stirring the electrolyte while introducing the alkane and the oxidant into the electrolyte.

[0023] In some embodiments, after the alkane and the oxidant are introduced into the electrolyte for a period of time, the method further comprises:

[0024] Stop feeding the alkane and the oxidant into the electrolytic cell, and introduce an inert gas instead. Simultaneously, change the direction of the current between the first electrode and the second electrode, so that the metallic copper deposited on the second electrode dissolves into the electrolyte and is deposited on the first electrode to form metallic copper.

[0025] In some embodiments, the electrolytic cell further comprises an isolation membrane, the isolation membrane dividing the electrolytic cell into a first chamber and a second chamber, the isolation membrane being capable of allowing copper ions to pass through while isolating gas;

[0026] A power source is connected between the first electrode and the second electrode, and an alkane and an oxidant are introduced into the electrolyte. The step of oxidizing the alkane comprises:

[0027] An alkane and an oxidant are introduced into the first chamber, and an inert gas is introduced into the second chamber, while the first electrode in the first chamber is connected to the positive electrode of a power supply, and the second electrode in the second chamber is connected to the negative electrode of a power supply;

[0028] After a certain period of time, the introduction of alkane and oxidant into the first chamber is stopped and replaced by the introduction of inert gas into the first chamber, and the introduction of inert gas into the second chamber is stopped and replaced by the introduction of alkane and oxidant into the second chamber, while the first electrode in the first chamber is connected to the negative pole of the power supply and the second electrode in the second chamber is connected to the positive pole of the power supply; and the above two steps are repeated multiple times.

[0029] In a second aspect, the present application provides a reaction device for implementing the alkane oxidation method according to the first aspect, the reaction device comprising:

[0030] An electrolytic cell comprises a shell and a first electrode and a second electrode arranged in the shell. The shell is filled with an electrolyte. The shell is also provided with a gas inlet and a gas outlet. The gas inlet is used to introduce alkanes. The first electrode and the second electrode are respectively inserted into the electrolyte.

[0031] In some embodiments, the electrolytic cell comprises a first chamber and a second chamber, the first electrode is disposed in the first chamber, and the second electrode is disposed in the second chamber;

[0032] The gas inlet includes a first gas inlet and a second gas inlet, the first gas inlet is arranged on the first chamber, and the second gas inlet is arranged on the second chamber;

[0033] The gas outlet includes a first gas outlet and a second gas outlet, the first gas outlet is provided on the first chamber, and the second gas outlet is provided on the second chamber;

[0034] An isolation membrane is provided between the first chamber and the second chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0036] FIG1 is a schematic structural diagram of the reaction apparatus provided in Example 1 of the present application.

[0037] Figure 2 is a schematic structural diagram of the reaction device provided in Example 20 of the present application.

[0038] FIG3 is a comparison chart of the test results of Examples 1-6 of the present application.

[0039] FIG4 is a comparison chart of the test results of Example 1, Comparative Example 1, and Examples 7-9.

[0040] FIG5 is a comparison chart of the test results of Example 1, Comparative Example 2, and Examples 10-14.

[0041] FIG6 is a comparison chart of the test results of Example 1 and Examples 15-19.

[0042] FIG7 is a graph showing the test results of Example 20 of the present application after a reaction time of 10 hours.

[0043] Reference numerals:

[0044] 10-shell; 11-first chamber; 12-second chamber; 20-first electrode; 30-second electrode; 40-gas inlet; 41-first gas inlet; 42-second gas inlet; 50-gas outlet; 51-first gas outlet; 52-second gas outlet; 60-reference electrode; 61-first reference electrode; 62-second reference electrode; 70-isolating membrane. DETAILED DESCRIPTION

[0045] Below in conjunction with embodiment and example, the application is described in further detail.These embodiment and example are only used to illustrate the application and are not used to limit the scope of the application. The purpose of providing these embodiment and example is to make the understanding of the disclosure of the application more thorough and comprehensive. It should also be understood that the application can be implemented in many different forms and is not limited to the embodiment and example described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the application, and the equivalent form obtained also falls within the protection scope of the application. In addition, in the description below, a large amount of specific details are given to provide a more complete understanding of the application. It should be understood that the application can be implemented without one or more of these details.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0047] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0048] In this application, the terms "first" and "second" in "the first aspect" and "the second aspect" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, "first" and "second" serve only as non-exhaustive enumeration and description and should be understood not to constitute a closed-ended limitation on quantity.

[0049] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0050] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly enumerating each integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0051] All documents mentioned in this application are cited as references in this application, just as each document is cited as a reference individually. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited in their entirety and for all purposes. When cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When cited documents are involved in this application, the examples and preferred embodiments of the cited relevant technical features may also be incorporated into this application as references, but are limited to the ability to implement this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be adaptively amended according to the description in this application.

[0052] In traditional technology, the direct conversion of alkanes into high-value-added chemical products such as alkenes and their oxygen-containing derivatives usually requires high temperature (200°C to 600°C) or high pressure (5bar to 50bar), and the reaction process has high energy consumption and high carbon emissions. In addition, traditional electrochemical activation of alkanes generally uses precious metal catalysts, which have a complex preparation process and high cost. They are easily deactivated under reaction conditions, and the problem of over-oxidation of the products is serious, making it difficult to meet large-scale production needs. However, the present application uses copper-containing electrodes as the first electrode and the second electrode. The raw materials are cheap and easy to obtain, the reaction activity and selectivity are high, and it is easy to scale up, so as to realize the electrochemical activation of alkanes to prepare high-value-added chemical products at room temperature and pressure, avoiding the use of high-temperature and high-pressure equipment.

[0053] In a first aspect, the present application provides a method for oxidizing an alkane, comprising:

[0054] Providing an electrolytic cell, comprising an electrolyte, and a first electrode and a second electrode disposed in the electrolyte, wherein the electrolyte contains an acidic material, the material of the first electrode comprises copper, and the material of the second electrode comprises copper; and

[0055] A power source is connected between the first electrode and the second electrode, and an alkane and an oxidant are introduced into the electrolyte to oxidize the alkane.

[0056] The embodiments of the present application use an electrochemical method to oxidize alkanes to prepare high-value-added chemicals. The first electrode and the second electrode both include metallic copper. Using metallic copper as a catalyst can combine with oxygen and acidic solution at room temperature and pressure to form a large number of active sites, thereby enabling alkane activation reactions under mild conditions. The process of electrochemically activating alkanes at the first electrode is accompanied by the dissolution of the copper electrode; the copper ions dissolved in the electrolyte are deposited on the second electrode, achieving stable and efficient recycling of the copper catalyst, and realizing high-performance, long-term electrochemical activation of alkanes to prepare high-value-added chemical products. At the same time, copper materials are cheap and easy to obtain. Therefore, the present application has the advantages of simple method, low cost and easy scalability.

[0057] It is understood that one of the first electrode and the second electrode is a working electrode, and the other is a counter electrode. In some embodiments, the first electrode is a working electrode, and the second electrode is a counter electrode.

[0058] In some embodiments, the acidic material includes at least one of sulfuric acid, perchloric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, and hydroiodic acid.

[0059] In some embodiments, the hydrogen ion concentration in the electrolyte is 1×10 -7 Alternatively, the hydrogen ion concentration is 1.0 mol / L to 2.0 mol / L, under which the alkane oxidation performance is optimal.

[0060] In some embodiments, the electrolyte further contains copper salt.

[0061] In some embodiments, the copper salt includes at least one of Cu(ClO4)2, CuSO4, and CuCl2.

[0062] In some embodiments, the molar concentration of the copper salt in the electrolyte is 0.05 mol / L to 0.8 mol / L, for example, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L or 0.8 mol / L.

[0063] By controlling the molar concentration of the copper salt, the embodiments of the present application can achieve excellent alkane oxidation performance while suppressing significant hydrogen ion consumption. If the molar concentration of the copper salt is relatively low, severe hydrogen ion consumption may occur, resulting in a large amount of acid solution being wasted, affecting alkane oxidation; if the molar concentration of the copper salt is relatively high, it may reduce alkane oxidation performance. In some embodiments, the molar concentration of the copper salt is 0.2 mol / L to 0.4 mol / L, which can achieve relatively excellent alkane oxidation performance while requiring minimal hydrogen ion consumption (<0.1 mol / L).

[0064] In some embodiments, the alkane includes at least one of a chain alkane and a cyclic alkane, for example, the alkane is selected from low-carbon alkanes with 1 to 4 carbon atoms, high-carbon alkanes with 5 to 20 carbon atoms, and cycloalkanes with 3 to 20 carbon atoms.

[0065] In some embodiments, the product after oxidation of the alkane, i.e., the high value-added chemical, includes at least one of olefins, alkynes, alcohol compounds, carboxylic acid compounds, ketone compounds, aldehyde compounds, ester compounds, phenolic compounds and ether compounds.

[0066] In some embodiments, the oxidant comprises at least one of an organic peroxide, ozone, hydrogen peroxide, oxygen, and air.

[0067] In some embodiments, the alkane and the oxidant can be introduced into the electrolyte in the form of a mixed gas, and the flow rate of the mixed gas can be, for example, 1 mL / min to 15 mL / min, specifically 1 mL / min, 2 mL / min, 4 mL / min, 6 mL / min, 8 mL / min, 10 mL / min, 12 mL / min or 15 mL / min.

[0068] In some embodiments, based on the total volume of the mixed gas of the alkane and the oxidant as 100%, the volume proportion of the oxidant is 5% to 50%, for example, it can be 5%, 10%, 15%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48% or 50%.

[0069] In some embodiments, the power supply may be a direct current power supply, wherein the positive electrode of the power supply may be connected to the first electrode serving as the working electrode, and the negative electrode of the power supply may be connected to the second electrode serving as the counter electrode.

[0070] In some embodiments, the electrolytic cell further comprises a reference electrode. In some embodiments, the method further comprises controlling the voltage between the working electrode and the reference electrode to be a constant voltage.

[0071] In some embodiments, the voltage of the working electrode relative to the standard hydrogen electrode (SHE) is 0.4V to 1.4V, for example, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V, 1.0V, 1.1V, 1.2V, 1.3V or 1.4V. In some embodiments, the reference electrode is a standard hydrogen electrode. In other embodiments, the reference electrode can be another type of electrode, such as a mercury / mercurous sulfate electrode filled with a saturated potassium sulfate solution, and the voltage between the working electrode and the reference electrode can be converted according to the voltage relative to the standard hydrogen electrode. For example, when the reference electrode is a mercury / mercurous sulfate electrode, since the potential of the mercury / mercurous sulfate electrode at room temperature and pressure (temperature of 25°C, pressure of 1.0 atm) is 0.645V (vs. SHE), the voltage between the working electrode and the reference electrode can be controlled to be a constant voltage, and is -0.245V to 0.755V.

[0072] The present invention controls the applied voltage during the electrolysis process, effectively regulating the alkane activation performance. A relatively low voltage may result in poor alkane activation activity; a relatively high voltage may cause excessive copper dissolution, affecting the stability of the electrolytic cell and preventing long-term operation.

[0073] In other embodiments, instead of the voltage control step, the method includes controlling the current between the working electrode and the counter electrode to be a constant current.

[0074] In some embodiments, the current density between the working electrode and the counter electrode is 1 mA / cm 2 ~400mA / cm 2 , for example, it can be 66.7mA / cm 2 .

[0075] In some embodiments, the ambient temperature of the alkane oxidation reaction in the method (e.g., the temperature of the electrolyte) is 10°C to 40°C, for example, 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C or 40°C.

[0076] In some embodiments, the ambient pressure of the alkane oxidation reaction in the method is 0.5 atm to 1.5 atm, for example, 0.5 atm, 0.6 atm, 0.7 atm, 0.8 atm, 0.9 atm, 1.0 atm, 1.1 atm, 1.2 atm, 1.3 atm, 1.4 atm or 1.5 atm.

[0077] In some embodiments, after introducing an alkane and an oxidant into the electrolyte for a period of time, the introduction of the alkane and oxidant into the electrolytic cell is stopped and an inert gas is introduced instead. Simultaneously, the direction of the current is changed, for example, by connecting the positive electrode of the power supply to the second electrode and the negative electrode of the power supply to the first electrode. This allows the metallic copper deposited on the second electrode to dissolve into the electrolyte and deposit on the first electrode to form metallic copper. In this embodiment of the present application, by changing the direction of the current and introducing an inert gas, the first electrode is regenerated and recycled.

[0078] It is understood that in the embodiments of the present application, the inert gas refers to a gas that does not participate in the electrochemical reaction process, for example, it can be at least one of argon and nitrogen.

[0079] In some embodiments, the electrolyte is stirred during the reaction; optionally, the stirring speed is 1000 rpm to 2000 rpm.

[0080] The embodiment of the present application provides a reaction device, which is used to implement the alkane oxidation method according to the first aspect, and the reaction device comprises:

[0081] An electrolytic cell comprises a shell and a first electrode and a second electrode arranged in the shell. The shell is filled with an electrolyte. The shell is also provided with a gas inlet and a gas outlet. The gas inlet is used to introduce alkanes. The first electrode and the second electrode are respectively inserted into the electrolyte.

[0082] In some embodiments, the reaction device further comprises a power source.

[0083] In some embodiments, the reaction device further comprises a reference electrode, which is inserted into the electrolyte. It is understood that a reference electrode is an electrode designed to have a specific potential, providing a reference point of known potential for determining the potential of the first electrode during the electrochemical reaction. Typically, the reference electrode does not participate in the reaction; for example, the reference electrode may be a mercury / mercurous sulfate electrode.

[0084] In some embodiments, the electrolytic cell comprises a first chamber and a second chamber, the first electrode is disposed in the first chamber, and the second electrode is disposed in the second chamber;

[0085] The gas inlet includes a first gas inlet and a second gas inlet, the first gas inlet is arranged on the first chamber, and the second gas inlet is arranged on the second chamber;

[0086] The gas outlet includes a first gas outlet and a second gas outlet, the first gas outlet is provided on the first chamber, and the second gas outlet is provided on the second chamber;

[0087] An isolation membrane is provided between the first chamber and the second chamber, that is, the isolation membrane divides the first chamber and the second chamber in the housing. Optionally, the isolation membrane is used to conduct ions and block gases, such as oxygen. For example, the isolation membrane can be a perfluorosulfonic acid resin membrane.

[0088] Exemplarily, a method for oxidizing alkanes using the dual-chamber structure reaction device is provided, comprising the following steps:

[0089] First, an alkane and an oxidant are introduced into the first chamber through the first gas inlet. The first electrode in the first chamber is connected to the positive pole of a power supply, and the second electrode in the second chamber is connected to the negative pole of a power supply. An inert gas is then introduced into the second chamber through the second gas inlet. During the reaction, the first electrode in the first chamber dissolves copper ions in the electrolyte. The copper ions dissolved in the electrolyte pass through the isolation membrane and are deposited on the second electrode in the second chamber. Simultaneously, an electrochemical catalytic activation reaction occurs between the alkane and the oxidant on the surface of the first electrode, causing the alkane to be dehydrogenated and oxidized. A gaseous high-value added chemical is then discharged through the first gas outlet, forming a liquid high-value added chemical in the electrolyte.

[0090] After a period of reaction, the flow of the alkane and oxidant into the first gas inlet is stopped and replaced with an inert gas. The first electrode in the first chamber is connected to the negative pole of a power supply, and the second electrode in the second chamber is connected to the positive pole of a power supply. Simultaneously, the flow of the inert gas into the second gas inlet is stopped and replaced with the alkane and oxidant. During the reaction, the second electrode in the second chamber dissolves copper ions in the electrolyte. The copper ions dissolved in the electrolyte pass through the isolation membrane and are deposited on the first electrode in the first chamber. Simultaneously, an electrochemical catalytic activation reaction of the alkane and the oxidant occurs on the surface of the second electrode, causing the alkane to be dehydrogenated and oxidized. A gaseous high-value added chemical is output from the second gas outlet, forming a liquid high-value added chemical in the electrolyte.

[0091] In this method, the above two steps can be performed alternately multiple times.

[0092] The embodiment of the present application uses a reaction device with a dual-chamber structure to alternately perform electrochemical catalytic reactions and electrode deposition regeneration in two chambers to achieve continuous preparation of alkanes into high-value-added chemicals.

[0093] It is understandable that before the first electrode and the second electrode are used, the oxide layer on the surface of the electrodes is removed by grinding to prevent the presence of the oxide layer from affecting the use of the electrodes.

[0094] The embodiments of the present invention will be described in detail below with reference to the examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. For experimental methods in the following examples where specific conditions are not specified, reference is made to the guidance provided in the present invention, and may also be made according to experimental manuals or conventional conditions in the art, or according to conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0095] Example 1

[0096] This embodiment provides a reaction device, as shown in FIG1 , comprising an electrolytic cell, the electrolytic cell comprising a housing 10, a first electrode 20, a second electrode 30, and an electrolyte injected into the housing 10. The housing 10 is provided with a gas inlet 40 and a gas outlet 50. The first electrode 20 and the second electrode 30 are respectively inserted into the electrolyte. The first electrode 20 and the second electrode 30 are both pure copper, and have dimensions of 2 cm × 2 cm × 0.5 mm in length × width × height. The concentration of HClO4 in the electrolyte is 1 mol / L, and the concentration of Cu(ClO4)2 is 0.2 mol / L. The electrolytic cell also includes a reference electrode 60, which is inserted between the first electrode 20 and the second electrode 30. The reference electrode 60 is a mercury / mercurous sulfate electrode. The reaction device also includes an electrochemical workstation, which is used as a power supply to apply a constant voltage or constant current between the electrodes.

[0097] The above-mentioned reaction device is used to prepare high value-added chemicals using ethane and oxygen, including:

[0098] The first electrode 20 and the second electrode 30 are polished separately. The polishing process includes: first polishing with 800-grit sandpaper for 5 minutes, then polishing with 1500-grit sandpaper for 5 minutes, and finally washing the copper sheet with deionized water. Repeat the above steps three times to complete the polishing of the first electrode 20 and the second electrode 30;

[0099] The first electrode 20 and the second electrode 30 were reinserted into the electrolytic cell, and ethane and oxygen were introduced into the gas inlet 40 at a flow rate of 15 mL / min, with oxygen accounting for 20% of the total volume of the ethane and oxygen mixture. The first electrode 20 and the second electrode 30 were connected to the positive and negative poles of the power supply of the electrochemical workstation, respectively. The voltage between the first electrode 20 and the reference electrode 60 was controlled by the electrochemical workstation to be maintained at 0.355 V (i.e., 1 V vs. SHE). During the reaction, the electrolyte was stirred at 1500 rpm, the reaction temperature was 25° C., the reaction pressure was 1 atm, and the reaction was carried out for 30 min. A gaseous product was obtained at the gas outlet 50, and a liquid product was obtained in the electrolyte.

[0100] Example 2

[0101] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that the voltage between the first electrode 20 and the reference electrode 60 is maintained at -0.245 V, ie, 0.4 V vs. SHE.

[0102] Example 3

[0103] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that the voltage between the first electrode 20 and the reference electrode 60 is maintained at -0.045 V, ie, 0.6 V vs. SHE.

[0104] Example 4

[0105] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that the voltage between the first electrode 20 and the reference electrode 60 is maintained at 0.155 V, ie, 0.8 V vs. SHE.

[0106] Example 5

[0107] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that the voltage between the first electrode 20 and the reference electrode 60 is maintained at 0.555 V, ie, 1.2 V vs. SHE.

[0108] Example 6

[0109] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that the voltage between the first electrode 20 and the reference electrode 60 is maintained at 0.755 V, ie, 1.4 V vs. SHE.

[0110] Example 7

[0111] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the concentration of HClO 4 in the electrolyte was 0.1 mol / L.

[0112] Example 8

[0113] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the concentration of HClO 4 in the electrolyte was 0.5 mol / L.

[0114] Example 9

[0115] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the concentration of HClO 4 in the electrolyte was 2.0 mol / L.

[0116] Example 10

[0117] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that oxygen accounts for 5% of the total volume of ethane and oxygen.

[0118] Example 11

[0119] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that oxygen accounts for 10% of the total volume of ethane and oxygen.

[0120] Example 12

[0121] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that oxygen accounts for 30% of the total volume of ethane and oxygen.

[0122] Example 13

[0123] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that oxygen accounts for 40% of the total volume of ethane and oxygen.

[0124] Example 14

[0125] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that oxygen accounts for 50% of the total volume of ethane and oxygen.

[0126] Example 15

[0127] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the concentration of Cu(ClO4)2 in the electrolyte was 0.1 mol / L.

[0128] Example 16

[0129] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the concentration of Cu(ClO4)2 in the electrolyte was 0.4 mol / L.

[0130] Example 17

[0131] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the concentration of Cu(ClO4)2 in the electrolyte was 0.6 mol / L.

[0132] Example 18

[0133] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the concentration of Cu(ClO4)2 in the electrolyte was 0.8 mol / L.

[0134] Example 19

[0135] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that no Cu(ClO4)2 was added to the electrolyte, i.e., the concentration of Cu(ClO4)2 in the electrolyte was 0 mol / L.

[0136] Example 20

[0137] This embodiment provides a reaction device, as shown in Figure 2, including an electrolytic cell, which includes a shell 10, a first electrode 20 and a second electrode 30, an electrolyte injected into the shell 10, an isolation membrane 70, a first reference electrode 61 and a second reference electrode 62. The isolation membrane 70 is arranged in the shell 10, dividing the shell 10 into a first chamber 11 and a second chamber 12. The first chamber 11 is provided with a first gas inlet 41 and a first gas outlet 51; the second chamber 12 is provided with a second gas inlet 42 and a second gas outlet 52. The first electrode 20 and the first reference electrode 61 are arranged in the first chamber 11, and the second electrode 30 and the second reference electrode 62 are arranged in the second chamber 12. The isolation membrane 70 is a perfluorosulfonic acid resin membrane. The reaction device also includes an electrochemical workstation, which is used as a power supply to apply a constant voltage or a constant current between the electrodes.

[0138] Among them, the first electrode 20 and the second electrode 30 are both pure copper, and the length × width × height dimensions are 2cm × 2cm × 0.5mm, the concentration of HClO4 in the electrolyte is 1mol / L, the concentration of Cu(ClO4)2 is 0.2mol / L, and the first reference electrode 61 and the second reference electrode 62 are both mercury / mercurous sulfate electrodes.

[0139] The above-mentioned reaction device is used to prepare high value-added chemicals using ethane and oxygen, including:

[0140] The first electrode 20 and the second electrode 30 are polished separately. The polishing process includes: first polishing with 800-grit sandpaper for 5 minutes, then polishing with 1500-grit sandpaper for 5 minutes, and finally washing the copper sheet with deionized water. Repeat the above steps three times to complete the polishing of the first electrode 20 and the second electrode 30;

[0141] The first electrode 20 and the second electrode 30 were reinserted into the electrolytic cell. Ethane and oxygen were introduced into the first gas inlet 41 at a flow rate of 15 mL / min, with oxygen accounting for 20% of the total volume of the ethane and oxygen mixture. The first electrode 20 and the second electrode 30 were connected to the positive and negative poles of the electrochemical workstation, respectively. The electrochemical workstation was used to control the voltage between the first electrode 20 and the first reference electrode 61 to be maintained at 0.355 V, i.e., 1 V vs. SHE. Nitrogen was introduced into the second gas inlet 42 at a flow rate of 15 mL / min. During the reaction, the electrolyte was stirred at 1500 rpm. The reaction temperature was 25° C., and the reaction pressure was 1 atm. After 20 minutes of reaction, a gaseous product was obtained at the first gas outlet 51, and a liquid product was obtained in the electrolyte in the first chamber 11.

[0142] The gas introduced into the first gas inlet 41 was replaced with nitrogen at a flow rate of 15 mL / min. The first electrode 20 and the second electrode 30 were connected to the negative and positive poles of the electrochemical workstation, respectively. The gas introduced into the second gas inlet 42 was replaced with ethane and oxygen at a flow rate of 15 mL / min. The oxygen accounted for 20% of the total volume of the ethane and oxygen mixture. The voltage between the second electrode 30 and the second reference electrode 62 was controlled by the electrochemical workstation to be maintained at 0.355 V, i.e., 1 V vs. SHE. During the reaction, the electrolyte was stirred at 1500 rpm, the reaction temperature was 25° C., and the reaction pressure was 1 atm. After 20 minutes of reaction, a gaseous product was obtained at the second gas outlet 52, and a liquid product was obtained in the electrolyte of the second chamber 12.

[0143] Comparative Example 1

[0144] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that HClO4 is not added to the electrolyte.

[0145] Comparative Example 2

[0146] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that oxygen is not introduced.

[0147] The generation rates of the products prepared in the above examples and comparative examples were detected.

[0148] Figure 3 compares the test results of Examples 1-6. It can be seen that the product formation rate gradually increases with increasing applied voltage. Therefore, the present application controls the applied voltage during the electrolysis process to effectively regulate alkane activation performance. If the voltage is relatively low, the alkane activation activity may be poor; if the voltage is relatively high, the copper dissolution rate may be too rapid, affecting the stability of the electrolytic cell and making it impossible to ensure long-term operation of the electrolytic cell.

[0149] Figure 4 is a comparison chart of the test results of Example 1, Comparative Example 1, and Examples 7-9. It can be seen that as the concentration of HClO4 in the electrolyte increases, the product generation rate continues to increase; when the HClO4 concentration increases to 1.0 mol / L, until 2.0 mol / L, the product generation rate does not change much.

[0150] Figure 5 compares the test results for Example 1, Comparative Example 2, and Examples 10-14. It can be seen that the product formation rate increases with increasing oxygen content. The product formation rate reaches its maximum at an oxygen content of 30%. Further increasing the oxygen content to 50% causes the product formation rate to continue to decline due to insufficient alkane content.

[0151] Figure 6 is a comparison chart of the test results of Example 1 and Examples 15-19. It can be seen that when the concentration of Cu(ClO4)2 in the electrolyte increases from 0 mol / L to 0.1 mol / L, the rate of product generation does not change much, but the consumption of hydrogen ions during the reaction exceeds 0.2 mol / L; when the concentration of Cu(ClO4)2 continues to increase from 0.1 mol / L to 0.8 mol / L, the rate of product generation continues to decrease, and the consumption of hydrogen ions during the reaction is less than 0.1 mol / L. Therefore, the embodiment of the present application controls the molar concentration of the copper salt, which can suppress the large-scale consumption of hydrogen ions while achieving excellent alkane oxidation performance. If the molar concentration of the copper salt is relatively low, serious hydrogen ion consumption may occur, resulting in a large amount of acidic solution being wasted, affecting the oxidation of alkanes; if the molar concentration of the copper salt is relatively high, the oxidation performance of alkanes may be reduced. In some embodiments, the molar concentration of the copper salt is 0.2 mol / L to 0.4 mol / L, which can achieve relatively excellent alkane oxidation performance while requiring very little hydrogen ion consumption (<0.1 mol / L).

[0152] FIG7 is a graph showing the test results of Example 20 of the present application after a reaction of 10 h. It can be seen that the product generation rate remains stable during the 10 h reaction process.

[0153] Through the above examples and comparative examples, it can be seen that the embodiments of the present application use an electrochemical method to oxidize alkanes to prepare high-value-added chemicals. The first electrode and the second electrode both include copper. Using copper as a catalyst, it can combine oxygen and acidic solution at room temperature and pressure to form a large number of active sites, thereby enabling the activation reaction of alkanes under mild conditions. The process of electrochemically activating alkanes at the first electrode is accompanied by the dissolution of the copper electrode; the copper ions dissolved in the electrolyte are simultaneously deposited on the second electrode, achieving stable and efficient recycling of the copper catalyst, achieving a high-performance, long-term electrochemical activation of alkanes to prepare high-value-added chemical products, and the copper material is cheap and easy to obtain. Therefore, the present application has the advantages of simple method, low cost and easy scalability.

[0154] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0155] The above-described embodiments merely represent several embodiments of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for oxidizing an alkane, characterized in that, Comprising: Providing an electrolytic cell, including an electrolyte solution, and a first electrode and a second electrode disposed in the electrolyte solution, the electrolyte solution containing an acidic material, the material of the first electrode including copper, and the material of the second electrode including copper; and Connecting a power source between the first electrode and the second electrode, and introducing an alkane and an oxidant into the electrolyte solution to oxidize the alkane.

2. The method for oxidizing an alkane according to claim 1, characterized in that, The acidic material includes at least one of sulfuric acid, perchloric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, and hydroiodic acid.

3. The method for oxidizing an alkane according to claim 1 or 2, characterized in that, The concentration of hydrogen ions in the electrolyte is 1×10 -7 mol / L to 2.0 mol / L.

4. The oxidation method of the alkane according to any one of claims 1 to 3, characterized in that, The electrolyte solution further contains a copper salt.

5. The method for oxidizing an alkane according to claim 4, characterized in that, The copper salt includes at least one of Cu(ClO4)2, CuSO4, and CuCl2.

6. The method for oxidizing an alkane according to claim 4 or 5, characterized in that, The molar concentration of the copper salt in the electrolyte solution is 0.05 mol / L to 0.8 mol / L.

7. The oxidation method of alkane according to any one of claims 1 to 6, characterized in that, The alkane includes at least one of a linear alkane and a cyclic alkane.

8. The method for oxidizing an alkane according to any one of claims 1 to 7, characterized in that, The products after oxidation of the alkane include at least one of an alkene, an alkyne, an alcohol compound, a carboxylic acid compound, a ketone compound, an aldehyde compound, an ester compound, a phenolic compound, and an ether compound.

9. The oxidation method of the alkane according to any one of claims 1 to 8, characterized in that, The oxidant includes at least one of an organic peroxide, ozone, hydrogen peroxide, oxygen, and air.

10. The oxidation method of alkane according to any one of claims 1 to 9, characterized in that, Based on the total volume of the alkane and the oxidant being 100%, the volume ratio of the oxidant is 5% to 50%.

11. The oxidation method of the alkane according to any one of claims 1 to 10, characterized in that, The electrolytic cell further includes a reference electrode, and the method further includes controlling the voltage between the working electrode and the reference electrode to be a constant voltage.

12. The method for oxidizing an alkane according to claim 11, wherein the voltage of the working electrode relative to the standard hydrogen electrode is 0.4 V to 1.4 V.

13. The oxidation method of the alkane according to any one of claims 1 to 12, characterized in that, The temperature of the alkane oxidation reaction is 10°C to 40°C, and the pressure is 0.5 atm to 1.5 atm.

14. The oxidation method of the alkane according to any one of claims 1 to 13, characterized in that, The alkane and the oxidant are introduced into the electrolyte solution in the form of a mixed gas, and the flow rate of the mixed gas is 1 mL / min to 15 mL / min.

15. The oxidation method of the alkane according to any one of claims 1 to 14, characterized in that, It further includes stirring the electrolyte solution while introducing the alkane and the oxidant into the electrolyte solution.

16. The oxidation method of alkane according to any one of claims 1 to 15, characterized in that, After introducing the alkane and the oxidant into the electrolyte solution for a period of time, it further includes: Stopping introducing the alkane and the oxidant into the electrolytic cell, introducing an inert gas, and simultaneously changing the current direction between the first electrode and the second electrode to dissolve the metallic copper deposited on the second electrode into the electrolyte solution and deposit metallic copper on the first electrode.

17. The oxidation method of the alkane according to any one of claims 1 to 16, characterized in that, The electrolytic cell further includes a separator membrane, the separator membrane divides the electrolytic cell into a first chamber and a second chamber, and the separator membrane can allow copper ions to pass through while isolating gases; Connecting a power source between the first electrode and the second electrode, and introducing an alkane and an oxidant into the electrolyte solution to oxidize the alkane, the steps include: Introducing the alkane and the oxidant into the first chamber, introducing an inert gas into the second chamber, and simultaneously connecting the first electrode in the first chamber to the positive pole of the power source and connecting the second electrode in the second chamber to the negative pole of the power source; After a period of time, the introduction of alkane and oxidant into the first chamber is stopped and replaced with the introduction of inert gas into the first chamber, and the introduction of inert gas into the second chamber is stopped and replaced with the introduction of alkane and oxidant into the second chamber. At the same time, the first electrode in the first chamber is connected to the negative pole of the power supply, and the second electrode in the second chamber is connected to the positive pole of the power supply; and The above two steps are alternately carried out multiple times.

18. A reaction device, characterized in that, The reaction device is used to implement the oxidation method of alkane according to any one of claims 1 to 17. The reaction device includes: An electrolytic cell, which includes a housing and a first electrode and a second electrode arranged in the housing. The housing is filled with an electrolyte solution, and the housing is also provided with a gas inlet and a gas outlet. The gas inlet is used for introducing alkane; the first electrode and the second electrode are respectively inserted into the electrolyte solution.

19. The reaction device according to claim 18, characterized in that, The electrolytic cell includes a first chamber and a second chamber. The first electrode is arranged in the first chamber, and the second electrode is arranged in the second chamber; The gas inlet includes a first gas inlet and a second gas inlet. The first gas inlet is arranged on the first chamber, and the second gas inlet is arranged on the second chamber; The gas outlet includes a first gas outlet and a second gas outlet. The first gas outlet is arranged on the first chamber, and the second gas outlet is arranged on the second chamber; A separator is arranged between the first chamber and the second chamber.

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