Green and efficient acetaldehyde synthesis method

Abstract

The invention discloses a synthesis method of acetaldehyde, which is characterized in that ethane and water are used as raw materials, and acetaldehyde can be obtained with high selectivity and high yield through conversion under the condition of no catalyst and corona discharge. The method has the advantages of high selectivity, mild reaction conditions, no catalyst, high yield and the like. Under the condition of an electric field, water is energized to obtain high-activity species water free radical cations, inert carbon-hydrogen bonds in ethane are activated, and a new method is provided for converting inert compounds into compounds with high additional values.

Description

Technical Field

[0001] This invention relates to the field of synthetic chemistry, specifically a green and efficient method for synthesizing acetaldehyde. Background Technology

[0002] Facing the challenges of global energy structure transformation and environmental sustainability, ethane (C2H6), as an important component of natural gas, has become a hot topic in chemical research due to its efficient conversion and utilization. Ethane is a significant contributor to photochemical pollution and ozone formation in the atmosphere. Therefore, technologies for converting ethane into more valuable chemicals can not only reduce its negative environmental impact but also fully utilize this energy fuel. Ethane conversion has significant industrial implications because it can be transformed into high-value-added chemicals such as methanol, ethanol, ethylene, and acetaldehyde. However, due to the high stability of the CH bonds in ethane, its direct activation is more challenging than that of the corresponding olefins. Traditional ethane conversion processes typically require high-temperature, high-pressure catalysts, which limits its application and leads to high energy consumption and environmental burden. The main production routes for acetaldehyde include: catalytic oxidation of ethanol as a raw material; catalytic oxidation of ethylene as a raw material; and hydration reaction of acetylene as a raw material. In recent years, research progress in acetaldehyde production technology has mainly focused on improvements to the ethanol process and the development of new methods for preparing acetaldehyde using ethane as a raw material. Currently, methods for directly converting ethane to acetaldehyde have also been reported, but these require high-temperature, high-pressure metal catalysts and are accompanied by the production of other oxides, such as ethanol and acetic acid. Therefore, developing efficient, low-energy-consumption, and highly selective pathways to promote ethane conversion under mild conditions is extremely attractive to both academia and industry.

[0003] Water is the source of life and an indispensable component of nature. As one of the most abundant resources on Earth, it is extremely inexpensive to obtain and highly economical. Reactions involving water are not only environmentally friendly, generally producing no toxic byproducts, but also effectively reduce pollution. Furthermore, water is a renewable resource, making its use as a reactant perfectly aligned with the principles of sustainable development, providing crucial support for green chemistry and ecological protection. Recent research has reported that energizing water under an electric field to generate water free radical cations exhibits high reactivity. Therefore, exploring the reaction of water free radical cations with ethane is of significant importance for promoting sustainable development.

[0004] This invention designs a novel reactor to simulate the ionization of water vapor under discharge, using inert gas ethane as the medium, to explore whether oxygen-containing compounds and other substances are generated, providing a new approach to the transformation of inert compounds. At the same time, the study of the selective transformation of alkanes also has important scientific value. Summary of the Invention

[0005] The purpose of this invention is to provide a novel reaction for the efficient and rapid synthesis of acetaldehyde based on the reaction of water free radical cations with ethane. This invention can provide new ideas for research on gaseous alkanes. The technical solution of this invention is as follows:

[0006] A method for synthesizing acetaldehyde involves the following steps: In a completely sealed ethane atmosphere, water evaporates to produce water vapor, which, under the influence of an electric field, enables water molecules to generate water free radical cations. Subsequently, the water free radical cations react with ethane to obtain acetaldehyde.

[0007] Furthermore, the volume of the ethane is 8-12 L.

[0008] Furthermore, the volume of the water is 0.8-1L.

[0009] Furthermore, the completely sealed ethane atmosphere specifically refers to the introduction of ethane into the reaction device, which includes a discharge reaction chamber, inside which a negative electrode plate and an array plate are arranged. The negative electrode plate is connected to the negative terminal of the high-voltage power supply, and the array plate is connected to the positive terminal of the high-voltage power supply.

[0010] Furthermore, the voltage of the high-voltage power supply is 7-8kV.

[0011] Furthermore, a plurality of discharge needles are disposed below the array plate, and a reaction space is formed between the tip of the discharge needle and the negative electrode plate, and the distance between the tip of the discharge needle and the negative electrode plate is 10-14 mm, and the ethane gas occupies the reaction space.

[0012] Furthermore, the discharge needle is a tungsten needle, the spacing between the discharge needles is between 3 and 8 mm, and the radius of curvature of the needle tip is between 0.01 and 0.1 mm.

[0013] Furthermore, an acetaldehyde detection colorimetric reagent is also placed in the discharge reaction chamber.

[0014] Furthermore, the acetaldehyde detection colorimetric reagent is an acidic potassium permanganate solution.

[0015] The beneficial effects of this invention are as follows: This invention utilizes a discharge reaction chamber to generate water free radical cation clusters from room temperature water. The formed water free radical cation clusters react with ethane gas to generate acetaldehyde free radical cations; an electron is gained in the negative electrode to generate the target compound. The purpose of this invention is to provide a new, catalyst-free, room temperature reaction between water and ethane for the green and efficient synthesis of acetaldehyde. This invention can provide new ideas for the research of inert alkane compounds. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0017] Figure 1 This is a schematic diagram of the acetaldehyde preparation device according to an embodiment of the present invention; wherein, 1-gas output channel, 2-gas source inlet, 3-water input channel, 4-discharge needle, 5-positive electrode of high voltage power supply, 6-negative electrode of high voltage power supply; 7-product output channel, 8-array plate, 9-reaction space, 10-discharge reaction chamber, 11-negative electrode plate;

[0018] Figure 2 Mass spectra of acetaldehyde prepared by the reaction of water free radical cations with ethane and compared with standard acetaldehyde;

[0019] Figure 3 The gas chromatograms of acetaldehyde prepared by the reaction of water free radical cations with ethane and the standard acetaldehyde are compared.

[0020] Figure 4 This is the reaction pathway of water free radical cations with ethane. Detailed Implementation

[0021] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0023] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0025] Please see Figure 1-4 This invention proposes a green and efficient method for synthesizing acetaldehyde, and the preparation apparatus used in this reaction ( Figure 1Specifically, the reaction chamber 10 includes a negative electrode plate 11 and an array plate 12. The negative electrode plate 11 is connected to the negative terminal 6 of a high-voltage power supply, and the array plate 12 is connected to the positive terminal 5 of the high-voltage power supply. Several discharge needles 4 are positioned below the array plate 8, forming a reaction space 9 between the tip of the discharge needle 4 and the negative electrode plate 11, with a distance of 10-14 mm between the tip of the discharge needle 4 and the negative electrode plate 11. The ethane gas occupies the reaction space. The high-voltage power supply has a voltage of 6-8 kV, preferably 7.5 kV. The discharge reaction chamber is a rectangular cavity with a gas inlet 2 on the side. In practical applications, a condensation device is also connected to the side. Specifically, the condensation device can be a device containing a mixture of ice and water at zero degrees Celsius, used to condense the formed acetaldehyde product. After the reaction, the product is condensed into the sample collection area for easy removal.

[0026] The reaction is a one-pot process, where the reactants are placed together into the discharge reaction chamber. By increasing the surface area of ​​the water, the humidity in the environment is better maintained.

[0027] Specifically, the discharge needle 4 is made of tungsten needle, the spacing of the discharge needle 4 is optimized to be between 3 and 8 mm, and the radius of curvature of the needle tip is optimized to be between 0.01 and 0.1 mm.

[0028] Specifically,

[0029] Based on the above apparatus, the method for preparing acetaldehyde includes:

[0030] First, water is added to the negative electrode plate 11 through the water input channel 3. Specifically, the negative electrode plate can be a stainless steel tank. Ethane is used to replace the air in the device through the gas output channel 1 and the gas source inlet 2. After the system is in a closed state, the high voltage power supply is turned on to apply a high voltage to the discharge needle, so that the tip of the discharge needle generates a spark discharge and ionizes the surrounding water vapor to form water free radical cation clusters. The formed water free radical cation clusters react with ethane to produce acetaldehyde molecules. The acetaldehyde molecules are condensed into liquid through the condenser and finally form an acetaldehyde aqueous solution in the negative electrode plate 11 and the sample collection area.

[0031] The acetaldehyde aqueous solution formed in the sample collection area is removed and collected by opening the valve. Specifically, by applying a high voltage (7.5kV) to the discharge needle, a spark discharge is generated at the tip of the discharge needle. Under normal temperature and pressure (e.g., 25°C, one atmosphere), using ethane as the carbon source and water as the oxygen source, water free radical ion clusters are generated through high-voltage spark discharge. These water free radical cation clusters come into full contact with ethane and react to produce acetaldehyde molecules. The formed acetaldehyde molecules are collected by a condensation collection device, and water in the negative electrode plate is collected through product output channel 7.

[0032] The following examples verify the preparation results of the above amino acid preparation method:

[0033] Example 1

[0034] At room temperature and pressure, water is first placed on the negative electrode plate. Under reduced pressure, ethane gas is introduced into the chamber of the reaction apparatus. A high voltage (7.5kV) is applied to the discharge needle, and the reaction is carried out for 30 minutes to dissolve the generated acetaldehyde molecules into the water, thus obtaining acetaldehyde molecules.

[0035] Example 2

[0036] At room temperature and pressure, 0.9 L of water and 2 mL of ethanol were placed on the negative electrode plate. Under reduced pressure, argon gas was introduced into the chamber of the reaction apparatus (3 times). A high voltage (4 kV) was applied to the discharge needle, and the reaction was carried out for 60 minutes and 120 minutes respectively. The newly generated compounds were then detected.

[0037] Test 1: The product from Example 1 was analyzed by mass spectrometry and chromatography. Analysis of the mass spectrometry data revealed various ion peaks of acetaldehyde, at m / z 45, m / z 63, and m / z 67. Figure 2 (A). The ion m / z 45 of the product acetaldehyde was further screened by tandem mass spectrometry analysis. The data results are listed below. Figure 2 Tandem mass spectrometry data of acetaldehyde ions showed typical loss of methylation characteristic ions, resulting in a fragment peak at m / z 29, which is a typical characteristic of acetaldehyde loss of fragment ions. Simultaneously, gas chromatography data analysis revealed that the standard peak and sample peak of acetaldehyde appeared at the same position. Figure 3 As shown, the compound produced is acetaldehyde.

[0038] Test 2: The reaction solution from Experiment 2 was analyzed by mass spectrometry and gas chromatography. The data showed that new substances were produced in the reaction solution, and the amount of ethanol converted to acetaldehyde increased with the extension of reaction time. This indicates that the intermediate in the reaction between ethane and water may pass through ethanol and then be oxidized to acetaldehyde. A possible mechanism for this reaction is proposed as follows: Figure 4 As shown.

[0039] In summary, the acetaldehyde synthesis method proposed in this embodiment can be carried out at room temperature and pressure (referring to pressure) without the need for chemical catalysts, saving energy and being green and pollution-free.

[0040] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for synthesizing acetaldehyde, characterized in that, In a completely sealed ethane atmosphere, water evaporates to produce water vapor, which, under the influence of an electric field, enables water molecules to generate water free radical cations. Subsequently, the water free radical cations react with ethane to produce acetaldehyde.

2. The method for synthesizing acetaldehyde according to claim 1, characterized in that, The volume of the ethane is 8-12 L.

3. The method for synthesizing acetaldehyde according to claim 1, characterized in that, The volume of the water is 0.8-1L.

4. The method for synthesizing acetaldehyde according to claim 1, characterized in that, The completely sealed ethane atmosphere specifically refers to the introduction of ethane into the reaction device, which includes a discharge reaction chamber containing a negative electrode plate and an array plate. The negative electrode plate is connected to the negative terminal of a high-voltage power supply, and the array plate is connected to the positive terminal of the high-voltage power supply.

5. The method for synthesizing acetaldehyde according to claim 4, characterized in that, The voltage of the high-voltage power supply is 7-8kV.

6. The method for synthesizing acetaldehyde according to claim 1, characterized in that, Several discharge needles are arranged below the array plate, and a reaction space is formed between the tip of the discharge needle and the negative electrode plate. The distance between the tip of the discharge needle and the negative electrode plate is 10-14 mm, and the ethane gas occupies the reaction space.

7. The method for synthesizing ethane according to claim 6, characterized in that, The discharge needle is a tungsten needle, the spacing between the discharge needles is between 3 and 8 mm, and the radius of curvature of the needle tip is between 0.01 and 0.1 mm.

8. The method for synthesizing acetaldehyde according to claim 1, characterized in that, The discharge reaction chamber also contains an acetaldehyde detection colorimetric reagent.

9. The method for synthesizing acetaldehyde according to claim 8, characterized in that, The colorimetric reagent for acetaldehyde detection is an acidic potassium permanganate solution.

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