Alkane oxidation method and reaction device

Abstract

The present invention relates to the field of chemical technology, and in particular to an alkane oxidation method and a reaction device, the method comprising: providing an electrolytic cell, the electrolytic cell being filled with an electrolyte, and a first electrode and a second electrode arranged in the electrolyte, the electrolyte containing an acidic material, the material of the first electrode comprising copper, the material of the second electrode comprising copper, applying voltage to the first electrode and the second electrode, and introducing an alkane and an oxidant into the electrolyte to oxidize the alkane. The present application can prepare high value-added chemicals by activating alkanes at normal temperature and pressure, and has the characteristics of low cost and simple method.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to an alkane oxidation method and a reaction device. Background Art

[0002] The direct activation of hydrocarbon alkanes into high-value-added chemical products such as olefins, alkynes and their oxygen-containing derivatives has important economic value. However, due to the influence of 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, alkanes are converted into high-value-added chemicals using precious metals as working electrodes, which are extremely expensive and need to be carried out under 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. Summary of the invention

[0003] Based on this, an embodiment of the present application provides an alkane oxidation method and reaction device that can react at room temperature and pressure and has low cost.

[0004] In a first aspect, the present application provides a method for oxidizing an alkane, comprising:

[0005] An electrolytic cell is provided, wherein the electrolytic cell is filled with an electrolyte, and a first electrode and a second electrode are arranged in the electrolyte, the electrolyte contains an acidic material, the material of the first electrode includes copper, and the material of the second electrode includes copper;

[0006] A voltage is applied to the first electrode or the second electrode, and an alkane and an oxidant are introduced into the electrolyte to oxidize the alkane.

[0007] In some embodiments, the acidic material includes at least one of sulfuric acid, perchloric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, and hydroiodic acid.

[0008] In some embodiments, the hydrogen ion concentration in the electrolyte is 1×10 -7 mol / L~2.0mol / L.

[0009] In some embodiments, the electrolyte further contains a copper salt.

[0010] In some embodiments, the copper salt includes at least one of Cu(ClO4)2, CuSO4, and CuCl2.

[0011] In some embodiments, the molar concentration of the copper salt in the electrolyte is 0.05 mol / L to 0.8 mol / L.

[0012] In some embodiments, the alkane includes at least one of a chain alkane and a cyclic alkane.

[0013] 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.

[0014] In some embodiments, the oxidant includes at least one of an organic peroxide, ozone, hydrogen peroxide, oxygen, and air.

[0015] In some embodiments, based on the total volume of the alkane and the oxidant as 100%, the volume proportion of the oxidant is 5% to 50%.

[0016] In some embodiments, the voltage applied in the method is a constant voltage.

[0017] In some embodiments, the voltage applied in the method is 0.4V~1.4V.

[0018] 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.

[0019] In a second aspect, the present application provides a reaction device, which is used to implement the alkane oxidation method as described in the first aspect, and the reaction device comprises:

[0020] 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.

[0021] In some embodiments, the electrolytic cell is divided into 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;

[0022] The gas inlet comprises 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;

[0023] The gas outlet comprises 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;

[0024] An isolation membrane is arranged between the first chamber and the second chamber.

[0025] Compared with the traditional technology, this application has at least the following beneficial effects:

[0026] The present application adopts an electrochemical method to oxidize alkanes to prepare high value-added chemicals. The first electrode and the second electrode both include copper. Copper is used as a catalyst, and can form a large number of active sites in combination with an oxidant and an acidic solution at room temperature and pressure, thereby enabling the activation reaction of alkanes under mild conditions. The first electrode is accompanied by the dissolution of the copper electrode during the electrochemical activation of alkanes; 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 scale-up. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the reaction device provided in Example 1 of the present application.

[0028] Figure 2 This is a schematic diagram of the structure of the reaction device provided in Example 20 of the present application.

[0029] Figure 3 This is a comparison chart of the test results of Examples 1-6 of the present application.

[0030] Figure 4 It is a comparison chart of the test results of Example 1, Comparative Example 1, and Examples 7-9.

[0031] Figure 5 It is a comparison chart of the test results of Example 1, Comparative Example 2, and Examples 10-14.

[0032] Figure 6 It is a comparison chart of the test results of Example 1 and Examples 15-19.

[0033] Figure 7 This is a graph showing the test results of Example 20 of the present application after a reaction time of 10 hours.

[0034] Among them, 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-isolation membrane. DETAILED DESCRIPTION

[0035] Below in conjunction with embodiment and example, the application is further described in 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, is not limited to the embodiment and example described herein, and 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 number of specific details are given in order to provide a more comprehensive understanding of the application, and it should be understood that the application can be implemented without one or more of these details.

[0036] 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 belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0037] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0038] In this application, the terms "first", "second", etc. in "the first aspect", "the second aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0039] In the present 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.

[0040] 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, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges 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 for a broad range of quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0041] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the 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 the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of 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 modified adaptively according to the description of this application.

[0042] In traditional technology, the direct conversion of alkanes into high value-added chemical products such as olefins and their oxygen-containing derivatives usually requires high temperature (200℃~600℃) or high pressure (5bar~50bar), and the reaction process has high energy consumption and high carbon emissions. In addition, traditional electrochemical alkane activation technology 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 products is serious, making it difficult to meet large-scale production needs. However, this 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 achieve 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.

[0043] The first aspect of the present application provides a method for oxidizing alkanes, comprising:

[0044] An electrolytic cell is provided, wherein the electrolytic cell is filled with an electrolyte, and a first electrode and a second electrode are arranged in the electrolyte, the electrolyte contains an acidic material, the material of the first electrode includes copper, and the material of the second electrode includes copper;

[0045] A voltage is applied to the first electrode or the second electrode, and an alkane and an oxidant are introduced into the electrolyte to oxidize the alkane.

[0046] The present application adopts an electrochemical method to oxidize alkanes to prepare high value-added chemicals. The first electrode and the second electrode both include copper. Copper is used as a catalyst, which 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 first electrode is accompanied by the dissolution of the copper electrode during the electrochemical activation of alkanes; 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 scale-up.

[0047] It can be understood that when a voltage is applied to the first electrode, the first electrode is a working electrode and the second electrode is a counter electrode; when a voltage is applied to the second electrode, the first electrode is a counter electrode and the second electrode is a working electrode.

[0048] It can be understood that the present application prepares high value-added chemicals by oxidizing alkanes.

[0049] In some embodiments, the acidic material includes at least one of sulfuric acid, perchloric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, and hydroiodic acid.

[0050] In some embodiments, the hydrogen ion concentration in the electrolyte is 1×10 -7 Preferably, the hydrogen ion concentration is 1.0 mol / L to 2.0 mol / L, under which the alkane oxidation performance is optimal.

[0051] In some embodiments, the electrolyte further contains copper salt.

[0052] In some embodiments, the copper salt includes at least one of Cu(ClO4)2, CuSO4, and CuCl2.

[0053] In some embodiments, the molar concentration of the copper salt in the electrolyte is 0.05 mol / L~0.8 mol / L, for example, it can be 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.

[0054] The present application controls the molar concentration of the copper salt, which can achieve excellent alkane oxidation performance while suppressing a large amount of 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 the oxidation of the alkane; if the molar concentration of the copper salt is relatively high, the oxidation performance of the alkane may be reduced. The preferred molar concentration of the copper salt is 0.2 mol / L~0.4 mol / L, which can achieve relatively excellent alkane oxidation performance while requiring very little hydrogen ion consumption (<0.1 mol / L).

[0055] 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.

[0056] 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, phenolic compounds and ether compounds.

[0057] In some embodiments, the oxidant comprises at least one of an organic peroxide, ozone, hydrogen peroxide, oxygen, and air.

[0058] In some embodiments, based on the total volume 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%.

[0059] In some embodiments, the voltage applied in the method is a constant voltage.

[0060] In some embodiments, the voltage applied in the method is 0.4 V to 1.4 V, for example, 0.4 V, 0.5 V, 0.6 V, 0.7 V, 0.8 V, 0.9 V, 1.0 V, 1.1 V, 1.2 V, 1.3 V or 1.4 V. It should be noted that the voltage applied in the present application refers to the voltage relative to the standard hydrogen electrode.

[0061] The present application controls the applied voltage during the electrolysis process, which can effectively regulate the 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 fast, affecting the stability of the electrolytic cell and failing to ensure long-term operation of the electrolytic cell.

[0062] In some embodiments, the oxidation temperature in the method is 10°C~40°C, for example, it can be 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.

[0063] In some embodiments, the oxidation pressure in the method is 0.5atm~1.5atm, for example, it can be 0.5atm, 0.6atm, 0.7atm, 0.8atm, 0.9atm, 1.0atm, 1.1atm, 1.2atm, 1.3atm, 1.4atm or 1.5atm.

[0064] In some embodiments, after the reaction, the electrolytic cell stops introducing the alkane and the oxidant, introduces an inert gas instead, changes the direction of the current, and dissolves the copper deposited on the second electrode into the electrolyte, and deposits on the first electrode to form copper. The present application achieves regeneration of the first electrode and recycling by changing the direction of the current and introducing an inert gas.

[0065] It is to be understood that the inert gas in the present application refers to a gas that does not participate in the reaction during the electrochemical reaction, for example, it can be at least one of argon and nitrogen.

[0066] In some embodiments, the electrolyte is stirred during the reaction; optionally, the stirring speed is 1000 rpm to 2000 rpm.

[0067] The second aspect of the present application provides a reaction device, which is used to implement the alkane oxidation method as described in the first aspect, and the reaction device comprises:

[0068] 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.

[0069] In some embodiments, the reaction device further comprises a reference electrode, which is inserted into the electrolyte. It is understood that the reference electrode is an electrode designed to have a specific potential, which provides a reference point of known potential during the electrochemical reaction for determining the potential of the first electrode. Usually the reference electrode does not participate in the reaction, for example, the reference electrode can be a mercury / mercurous sulfate electrode.

[0070] In some embodiments, the electrolytic cell is divided into 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;

[0071] The gas inlet comprises 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;

[0072] The gas outlet comprises 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;

[0073] An isolation membrane is provided between the first chamber and the second chamber. Optionally, the isolation membrane is used to conduct ions and block oxygen, and may be, for example, a perfluorosulfonic acid resin membrane.

[0074] Exemplarily, a method for oxidizing alkanes using a reaction device in which the electrolytic cell is divided into a first chamber and a second chamber is provided, comprising:

[0075] Alkane and oxidant are introduced into the first chamber through the first gas inlet, and voltage is applied to the first electrode in the first chamber; inert gas is 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, and the copper ions dissolved in the electrolyte are simultaneously deposited on the second electrode, and at the same time, an electrochemical catalytic activation reaction occurs between the alkane and the oxidant on the surface of the first electrode, the alkane is dehydrogenated and oxidized, and a gaseous high-value additional chemical is output from the first gas outlet to form a liquid high-value additional chemical in the electrolyte;

[0076] Stop introducing alkane and oxidant into the first gas inlet, replace with introducing inert gas, stop applying voltage to the first electrode in the first chamber; simultaneously stop introducing inert gas into the second gas inlet, replace with alkane and oxidant, and apply voltage to the second electrode in the second chamber; electrochemical catalytic activity reaction of alkane occurs in the second chamber, and copper deposition is performed on the first electrode in the first chamber;

[0077] Perform the above steps alternately.

[0078] 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.

[0079] 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 avoid the oxide layer affecting the use of the electrodes.

[0080] The embodiments of the present invention will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are preferably referred to the guidance provided in the present invention, and can also be based on the experimental manual or normal conditions in this area, can also be based on the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0081] Example 1

[0082] This embodiment provides a reaction device such as Figure 1 As shown, it includes an electrolytic cell, a first electrode and a second electrode. The electrolytic cell includes a shell 10 injected with an electrolyte, a gas inlet 40 and a gas outlet 50 are opened on the shell 10, 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 the length×width×height dimensions are 2cm×2cm×0.5mm, the concentration of HClO4 in the electrolyte is 1mol / L, and the concentration of Cu(ClO4)2 is 0.2mol / L; it also includes a reference electrode 60, the reference electrode 60 is inserted between the first electrode 20 and the second electrode 30, and the reference electrode 60 is a mercury / mercurous sulfate electrode.

[0083] The above reaction device is used to prepare high value-added chemicals using ethane and oxygen, including:

[0084] The first electrode 20 and the second electrode 30 are polished respectively. 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. The above steps are repeated 3 times to complete the polishing of the first electrode 20 and the second electrode 30.

[0085] The first electrode 20 and the second electrode 30 are reinserted into the electrolytic cell, ethane and oxygen are introduced into the gas inlet 40 at a flow rate of 15 mL / min, wherein oxygen accounts for 20% of the total volume of the mixed gas of ethane and oxygen, and a voltage of 1 V (vs. SHE) is applied to the first electrode 20. During the reaction, the electrolyte is stirred at 1500 rpm, the reaction temperature is 25° C., the reaction pressure is 1 atm, the reaction is carried out for 30 minutes, and a gaseous product is obtained at the gas outlet 50, and a liquid product is obtained in the electrolyte.

[0086] Example 2

[0087] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the voltage applied to the first electrode was 0.4 V (vs. SHE).

[0088] Example 3

[0089] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the voltage applied to the first electrode was 0.6 V (vs. SHE).

[0090] Example 4

[0091] High value-added chemicals were prepared using ethane and oxygen according to the method of Example 1, except that the voltage applied to the first electrode was 0.8 V (vs. SHE).

[0092] Example 5

[0093] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that the voltage applied to the first electrode is 1.2 V (vs. SHE).

[0094] Example 6

[0095] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, except that the voltage applied to the first electrode is 1.4 V (vs. SHE).

[0096] Example 7

[0097] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that the concentration of HClO4 in the electrolyte is 0.1 mol / L.

[0098] Example 8

[0099] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that the concentration of HClO4 in the electrolyte is 0.5 mol / L.

[0100] Example 9

[0101] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that the concentration of HClO4 in the electrolyte is 2.0 mol / L.

[0102] Example 10

[0103] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that oxygen accounts for 5% of the total volume of ethane and oxygen.

[0104] Embodiment 11

[0105] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that oxygen accounts for 10% of the total volume of ethane and oxygen.

[0106] Example 12

[0107] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that oxygen accounts for 30% of the total volume of ethane and oxygen.

[0108] Example 13

[0109] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that oxygen accounts for 40% of the total volume of ethane and oxygen.

[0110] Embodiment 14

[0111] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that oxygen accounts for 50% of the total volume of ethane and oxygen.

[0112] Embodiment 15

[0113] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that the concentration of Cu(ClO4)2 in the electrolyte is 0.1 mol / L.

[0114] Example 16

[0115] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that the concentration of Cu(ClO4)2 in the electrolyte is 0.4 mol / L.

[0116] Embodiment 17

[0117] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that the concentration of Cu(ClO4)2 in the electrolyte is 0.6 mol / L.

[0118] Embodiment 18

[0119] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that the concentration of Cu(ClO4)2 in the electrolyte is 0.8 mol / L.

[0120] Embodiment 19

[0121] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that no Cu(ClO4)2 is added to the electrolyte, that is, the concentration of Cu(ClO4)2 in the electrolyte is 0 mol / L.

[0122] Embodiment 20

[0123] This embodiment provides a reaction device such as Figure 2As shown, it includes an electrolytic cell, a first electrode 20 and a second electrode 30. The electrolytic cell includes a shell 10 injected with an electrolyte, and the shell is divided 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, and a first reference electrode 61 is also provided in the first chamber 11; the second chamber 12 is provided with a second gas inlet 42 and a second gas outlet 52, and a second reference electrode 62 is also provided in the second chamber 12; the first electrode 20 is provided in the first chamber 11, and the second electrode 30 is provided in the second chamber 12; the first chamber 11 and the second chamber 12 are separated by an isolation membrane 70, and the isolation membrane 70 is a perfluorosulfonic acid resin membrane.

[0124] 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.

[0125] The above reaction device is used to prepare high value-added chemicals using ethane and oxygen, including:

[0126] The first electrode 20 and the second electrode 30 are polished respectively. 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. The above steps are repeated 3 times to complete the polishing of the first electrode 20 and the second electrode 30.

[0127] The first electrode 20 and the second electrode 30 are reinserted into the electrolytic cell, ethane and oxygen are introduced into the first gas inlet 41 at a flow rate of 15 mL / min, wherein oxygen accounts for 20% of the total volume of the mixed gas of ethane and oxygen, and a voltage of 1 V (vs. SHE) is applied to the first electrode 20; 15 mL / min of nitrogen is introduced into the second gas inlet 42, and the electrolyte is stirred at 1500 rpm during the reaction. The reaction temperature is 25° C. and the reaction pressure is 1 atm. After reacting for 20 minutes, a gaseous product is obtained at the first gas outlet 51, and a liquid product is obtained in the electrolyte of the first chamber 11;

[0128] The gas introduced into the first gas inlet 41 was replaced with nitrogen at a flow rate of 15 mL / min, and the voltage applied to the first electrode 20 was stopped; the gas introduced into the second gas inlet 42 was replaced with ethane and oxygen, the gas flow rate was 15 mL / min, oxygen accounted for 20% of the total volume of the mixed gas of ethane and oxygen, and a voltage of 1 V (vs. SHE) was applied to the second electrode 30; during the reaction, the electrolyte was stirred at 1500 rpm, the reaction temperature was 25°C, the reaction pressure was 1 atm, and 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.

[0129] Comparative Example 1

[0130] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that HClO4 is not added to the electrolyte.

[0131] Comparative Example 2

[0132] High value-added chemicals are prepared using ethane and oxygen according to the method of Example 1, the only difference being that oxygen is not introduced.

[0133] The generation rates of the products prepared in the above examples and comparative examples were detected.

[0134] in, Figure 3 The comparison chart of the test results of Examples 1-6 shows that as the applied voltage increases, the product generation rate gradually increases. Therefore, the present application controls the applied voltage during the electrolysis process, which can effectively regulate the 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 fast, affecting the stability of the electrolytic cell, and it is impossible to ensure the long-term operation of the electrolytic cell.

[0135] Figure 4 This is a comparison chart of the test results of Example 1, Comparative Example 1, and Examples 7-9. It can be seen that with the increase of the HClO4 concentration in the electrolyte, 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.

[0136] Figure 5 The test results of Example 1, Comparative Example 2, and Examples 10-14 are compared. It can be seen that as the oxygen ratio increases, the product generation rate continues to increase. When the oxygen content is 30%, the product generation rate reaches the maximum value. After further increasing the oxygen content to 50%, the product generation rate continues to decrease due to the insufficient alkane content.

[0137] Figure 6It 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 0mol / L to 0.1mol / L, the product generation rate does not change much, but the consumption of hydrogen ions during the reaction exceeds 0.2mol / L; when the concentration of Cu(ClO4)2 continues to increase from 0.1mol / L to 0.8mol / L, the product generation rate continues to decrease, and the consumption of hydrogen ions during the reaction is less than 0.1mol / L. Therefore, the present application controls the molar concentration of copper salt, which can suppress the large consumption of hydrogen ions while achieving excellent alkane oxidation performance. If the molar concentration of 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 copper salt is relatively high, the oxidation performance of alkanes may be reduced. The preferred molar concentration of copper salt is 0.2mol / L~0.4mol / L, which can achieve relatively excellent alkane oxidation performance while requiring very little hydrogen ion consumption (<0.1mol / L).

[0138] Figure 7 This is a test result diagram of Example 20 of the present application after a reaction of 10 hours. It can be seen that the product generation rate remains stable during the 10-hour reaction process.

[0139] Through the above embodiments and comparative examples, it can be seen that the present application adopts an electrochemical method to oxidize alkanes to prepare high value-added chemicals. The first electrode and the second electrode both include copper. Copper is used as a catalyst, which 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 first electrode is accompanied by the dissolution of the copper electrode during the electrochemical activation of alkanes; 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 scale.

[0140] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0141] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for oxidizing alkanes, characterized in that: include: An electrolytic cell is provided, wherein the electrolytic cell is filled with an electrolyte, and a first electrode and a second electrode are arranged in the electrolyte, the electrolyte contains an acidic material and a copper salt, the molar concentration of the copper salt in the electrolyte is 0.2 mol / L to 0.4 mol / L, the material of the first electrode includes copper, and the material of the second electrode includes copper; A voltage is applied to the first electrode or the second electrode, and an alkane and an oxidant are introduced into the electrolyte to oxidize the alkane.

2. The method for oxidizing alkanes according to claim 1, characterized in that: The electrolyte satisfies at least one of the following conditions: (1) The acidic material includes at least one of sulfuric acid, perchloric acid, phosphoric acid, hydrochloric acid, hydrobromic acid and hydroiodic acid; (2) The concentration of hydrogen ions in the electrolyte is 1×10 -7 mol / L~2.0mol / L.

3. The method for oxidizing alkanes according to claim 1, characterized in that: The copper salt includes at least one of Cu(ClO4)2, CuSO4 and CuCl2.

4. The method for oxidizing alkanes according to claim 1, characterized in that: The alkane includes at least one of a chain alkane and a cyclic alkane.

5. The method for oxidizing alkanes according to claim 1, characterized in that: The product after the 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.

6. The method for oxidizing alkanes according to claim 1, characterized in that: The oxidant satisfies at least one of the following conditions: (1) The oxidant comprises at least one of an organic peroxide, ozone, hydrogen peroxide, oxygen and air; (2) Based on the total volume of the alkane and the oxidant as 100%, the volume proportion of the oxidant is 5% to 50%.

7. The method for oxidizing alkanes according to any one of claims 1 to 6, characterized in that: The method satisfies at least one of the following conditions: (1) The voltage applied in the method is a constant voltage; (2) The oxidation temperature in the method is 10°C to 40°C and the pressure is 0.5atm to 1.5atm.

8. The method for oxidizing alkanes according to claim 7, characterized in that: The voltage applied in the method is a constant voltage, and the voltage applied in the method is 0.4V to 1.4V.

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