CN101126163A - Method for preparing aldehyde by using glow discharging to electrolyze ethanol solution - Google Patents
Method for preparing aldehyde by using glow discharging to electrolyze ethanol solution Download PDFInfo
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- CN101126163A CN101126163A CNA2007100297018A CN200710029701A CN101126163A CN 101126163 A CN101126163 A CN 101126163A CN A2007100297018 A CNA2007100297018 A CN A2007100297018A CN 200710029701 A CN200710029701 A CN 200710029701A CN 101126163 A CN101126163 A CN 101126163A
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Abstract
The invention relates to an acetaldehyde preparation technology and discloses an acetaldehyde preparation method by using glow discharging to electrolyze an ethanol solution. The method comprises the following steps: mixing the ethanol and the water according to the volume ratio of 1:0 to 15, and the mixed solution is added with an electrolyte until the electric conduction rate reach 0.005 to 50000S.m minus 1; placing the prepared solution into the glow discharging electrolysis reactor which contains a cathode and an anode and connecting the power supply, in addition, the acetaldehyde is generated after the electrolyzing voltage of the glow discharging is beyond the voltage at the discharging transiting point of the glow discharging operation; the gases generated from the glow discharging electrolyzing production is segregated and purified to obtain high purity hydrogen; finally, the solution inside the segregating reactor is rectified to get the acetaldehyde. The preparation technique of the acetaldehyde in the invention is simple and has small sized device; wherein, the reacting condition is tender with a normal temperature and normal pressure reaction without any catalyst; the energy consumption in the producing process is low while with high efficiency; furthermore, the invention is able to effectively recover hydrogen atom in the ethanol molecule.
Description
Technical Field
The invention relates to an acetaldehyde preparation technology, in particular to a method for preparing acetaldehyde by electrolyzing ethanol solution through glow discharge.
Background
Acetaldehyde is an important organic feedstock and the world acetaldehyde production capacity in 1998 is 307 million t/a. Downstream products of acetaldehyde include acetic acid, acetate, ethyl acetate, pentaerythritol, threonine, pyridine series, 3-hydroxybutyraldehyde, 1, 3-butanediol, cinnamaldehyde, chloral, peracetic acid, lactic acid, glyoxal, glyoxylic acid, allantoin, and the like. In addition, many highly advantageous small-scale acetaldehyde derivative products are put into production. Acetaldehyde, for example, is used in the production of poly (n-vinylacetamide) (PNVA), a novel functional polymeric adsorbent, using acetic acid, acetaldehyde and ammonia as starting materials. India has a production technology for preparing Vinyl Acetate Monomer (VAM) by using acetaldehyde and acetic anhydride as raw materials to react and hydrolyzing a vinyl diacetate intermediate. Worldwide VAM is a scaled product, with an estimated current annual yield of approximately 400 tens of thousands of tons.
The ethanol route is one of the main acetaldehyde production processes in China at present. After ethanol reacts in an oxidation reaction furnace to generate acetaldehyde, a dilute acetaldehyde solution containing 3.5-7.5% (mole fraction) of acetaldehyde is formed, and the dilute acetaldehyde solution enters an acetaldehyde rectifying tower to be separated, so that an acetaldehyde product is obtained. In the ethanol oxidation process, H atoms in ethanol molecules are discharged in the form of water,so that the concentration of acetaldehyde in a reaction system is reduced, and resource waste is caused. Acetaldehyde may also be synthesized by ethylene oxidation, i.e., using ethylene and oxygen as raw materials. The reaction process of the ethylene oxidation method usually uses palladium chloride and copper chloride as catalysts, and ethylene and oxygen undergo oxidation reaction to generate acetaldehyde. The acetaldehyde can also be produced by the acetylene hydration method.
In both the ethylene oxidation process and the acetylene hydration process, the reaction requires a catalyst and a relatively high reaction temperature, and the reaction equipment used is bulky.
Disclosure of Invention
The invention aims to provide a method for preparing acetaldehyde by electrolyzing ethanol solution through glow discharge aiming at the defects of the prior art. The purpose of the invention is realized by the following scheme:
a method for preparing acetaldehyde by ethanol solution glow discharge electrolysis comprises the following steps:
(1) mixing ethanol and water in a volume ratio of 1: 0-15 to form a solution, and adding electrolyte to the solution until the conductivity of the solution reaches 0.005E50000S.m-1；
(2) Putting the solution prepared in the step (1) into a glow discharge electrolysis reactor containing a cathode and an anode, switching on a power supply, and producing acetaldehyde, wherein the glow discharge electrolysis voltage exceeds the glow discharge transition point voltage;
(3) separating and purifying the hydrogen generated in the step (2) to obtain high-purity hydrogen;
(4) and (3) rectifying and separating the solution in the reactor in the step (2) to obtain acetaldehyde.
The power supply is a high-voltage direct-current power supply or a high-voltage direct-current pulse power supply, and the output voltage of the power supply is more than or equal to 100V.
The discharge electrode material of the glow discharge electrolysis reactor is any one of tungsten, tungsten-cerium alloy, platinum and platinum alloy.
When the cathode of the glow discharge electrolysis reactor is in glow discharge, the ratio of the area of the cathode electrode to the area of the anode electrode of the glow discharge electrolysis reactor is 1: 1-10000.
When the anode of the glow discharge electrolysis reactor is in glow discharge, the ratio of the area of the anode electrode to the area of the cathode electrode of the glow discharge electrolysis reactor is 1: 0.8-10000.
Ethanol molecules are collided and excited by high-energy electrons in glow discharge plasma, various bonds in the molecules are recombined after being broken, and finally acetaldehyde and hydrogen are produced, wherein the reaction is shown as a formula (1).
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. simple process and small equipment.
2. The reaction condition is mild, the reaction is normal temperature and normal pressure, and no catalyst is needed.
3. The production process has low energy consumption and high efficiency. The liquid medium is favorable for transferring energy to the reaction system so as to meet the activation energy required by the breakage of chemical bonds in the chemical reaction process, and the neck bottle which is difficult to transfer energy to the reaction system when gas is taken as a material can be avoided. According to the reforming conditions of the invention, the energy consumption of the prepared hydrogen per unit volume is low.
4. Can effectively recover hydrogen atoms in ethanol molecules to obtain a high-concentration hydrogen byproduct. The hydrogen content in the byproduct gas of acetaldehyde produced by the process and the device of the invention reaches more than 70 percent.
Detailed Description
The present invention will be further described in detail with reference to the following examples, but the examples of the present invention are not limited thereto.
Example 1: the metal tungsten is used as the cathode material of the glow discharge electrolysis reactor, and the ratio of the area of the cathode electrode to the area of the anode electrode is 1: 1. The ethanol solution is electrolyzed by glow discharge to prepare acetaldehyde according to the following steps.
(1) Mixing ethanol and water at a volume ratio of 1: 0 to obtain a solution, adding sodium hydroxide as an auxiliary electrolyte, and adjusting the conductivity of the solution to 5S.m-1；
(2) Putting the prepared ethanol solution into a glow discharge-containing electrolytic reactor, switching on a power supply, and carrying out cathode glow discharge electrolysis with the electrolytic voltage of two poles of 100V; producing acetaldehyde, which is dissolved in the electrolyte;
(3) the hydrogen-rich gas from the glow discharge electrolytic reactor is dried and purified, the molar concentration of the hydrogen reaches 82.67 percent, the molar concentration of the carbon monoxide is 4.17 percent, the molar concentration of the methane is 5.28 percent, the molar concentration of the ethane is 2.48 percent, the molar concentration of the propane is 4.24 percent, and the energy consumption of the gas per unit volume is 5.12 multiplied by 103kJ/Nm3The hydrogen-rich gas is separated by pressure swing adsorption to obtain high-purity hydrogen;
(4) the ethanol solution containing acetaldehyde is removed from the glow discharge electrolytic reactor, the ethanol solution is separated by a rectifying tower, the acetaldehyde comes out from the top of the rectifying tower, the acetaldehyde yield is 81.9 percent, and the ethanol and the water can be recycled after the ethanol and the water are discharged from a tower kettle and the conductivity and the concentration are adjusted.
Example 2: the tungsten-cerium alloy is used as the cathode material of the glow discharge electrolysis reactor, and the ratio of the area of the cathode electrode to the area of the anode electrode is 1: 10000. The ethanol solution is electrolyzed by glow discharge to prepare acetaldehyde according to the following steps.
(1) Mixing ethanol and water at a volume ratio of 1: 0 to obtain a solution, adding sodium hydroxide as an auxiliary electrolyte, and adjusting the conductivity of the solution to 0.005S.m-1；
(2) Putting the prepared ethanol solution into a glow discharge-containing electrolytic reactor, switching on a power supply, and carrying out anode glow discharge electrolysis with the electrolytic voltage of two electrodes being 1000V; producing acetaldehyde, which is dissolved in the electrolyte;
(3) the hydrogen-rich gas from the glow discharge electrolytic reactor is dried and purified, the molar concentration of the hydrogen is 74.16 percent, the molar concentration of the carbon monoxide is 5.02 percent, the molar concentration of the methane is 6.98 percent, the molar concentration of the ethane is 4.64 percent, the molar concentration of the propane is 6.52 percent, and the energy consumption of the gas per unit volume is 64.45 multiplied by 103kJ/Nm3，The hydrogen-rich gas is subjected to pressure swing adsorption separation to obtain high-purity hydrogen;
(4) the ethanol solution containing acetaldehyde is removed from the glow discharge electrolytic reactor, the ethanol solution is separated by a rectifying tower, the acetaldehyde comes out from the top of the rectifying tower, the acetaldehyde yield is 68.3 percent, and the ethanol and the water can be recycled after the ethanol and the water are discharged from a tower kettle and the conductivity and the concentration are adjusted.
Example 3: platinum metal is used as a cathode material of the glow discharge electrolysis reactor, and the ratio of the area of the cathode electrode to the area of the anode electrode is 1: 5000. The ethanol solution is electrolyzed by glow discharge to prepare acetaldehyde according to the following steps.
(1) Mixing ethanol and water at a volume ratio of 1: 15 to obtain a solution, adding sodium hydroxide as an auxiliary electrolyte, and adjusting the conductivity of the solution to 10000S.m-1；
(2) Putting the prepared ethanol solution into a glow discharge-containing electrolytic reactor, switching on a power supply, and carrying out cathode glow discharge electrolysis with the electrolytic voltage of two poles of 100V; producing acetaldehyde, which is dissolved in the electrolyte;
(3) the hydrogen-rich gas from the glow discharge electrolysis reactor is dried and purified, the molar concentration of the hydrogen reaches 80.01 percent, the molar concentration of the carbon monoxide is 5.03 percent, the molar concentration of the methane is 6.59 percent, the molar concentration of the ethane is 4.18 percent, and the molar concentration of the carbon dioxide is 3.54 percentThe energy consumption per unit volume of gas is 35.72X 103kJ/Nm3The hydrogen-rich gas is separated by pressure swing adsorption to obtain high-purity hydrogen;
(4) the ethanol solution containing acetaldehyde is removed from the glow discharge electrolytic reactor, the ethanol solution is separated by a rectifying tower, the acetaldehyde comes out from the top of the rectifying tower, the acetaldehyde yield is 86.2 percent, and the ethanol and the water can be recycled after the ethanol and the water are discharged from a tower kettle and the conductivity and the concentration are adjusted.
Example 4: platinum alloy is used as anode material of glow discharge electrolysis reactor, and the ratio of anode electrode area to cathode electrode area is 1: 0.8. The ethanol solution is electrolyzed by glow discharge to prepare acetaldehyde according to the following steps.
(1) Mixing ethanol and water at a volume ratio of 2: 3 to obtain a solution, adding sodium hydroxide as auxiliary electrolyte, and adjusting the conductivity of the solution to 50000S.m-1；
(2) Putting the prepared ethanol solution into a glow discharge-containing electrolytic reactor, switching on a power supply, and carrying out cathode glow discharge electrolysis with the electrolytic voltage of two poles of 500V; producing acetaldehyde, which is dissolved in the electrolyte;
(3) the hydrogen-rich gas from glow discharge electrolytic reactor is dried and purified to obtain hydrogen gas with molarity up to 83.13%, carbon monoxide molarity 5.20%, methane molarity 4.06% and ethane molarityThe degree is 2.98%, the molar concentration of propane is 2.90%, and the energy consumption per unit volume of gas is 8.33X 103kJ/Nm3The hydrogen-rich gas is separated by pressure swing adsorption to obtain high-purity hydrogen;
(4) the ethanol solution containing acetaldehyde is removed from the glow discharge electrolytic reactor, the ethanol solution is separated by a rectifying tower, the acetaldehyde comes out from the top of the rectifying tower, the acetaldehyde yield is 83.2 percent, and the ethanol and the water can be recycled after the ethanol and the water are discharged from a tower kettle and the conductivity and the concentration are adjusted.
Example 5: platinum is used as anode material of glow discharge electrolysis reactor, and the ratio of the area of anode electrode to the area of cathode electrode is 1: 6000. The ethanol solution is electrolyzed by glow discharge to prepare acetaldehyde according to the following steps.
(1) Mixing ethanol and water at a volume ratio of 1: 8 to obtain a solution, and addingSodium hydroxide is used as auxiliary electrolyte to adjust the conductivity of the solution to 500S.m-1；
(2) Putting the prepared ethanol solution into a glow discharge-containing electrolytic reactor, switching on a power supply, and carrying out cathode glow discharge electrolysis with the electrolytic voltage of two poles of 400V; producing acetaldehyde, which is dissolved in the electrolyte;
(3) the hydrogen-rich gas from the glow discharge electrolytic reactor is dried and purified, the molar concentration of the hydrogen reaches 83.13 percent, the molar concentration of the carbon monoxide is 5.20 percent, the molar concentration of the methane is 4.06 percent, the molar concentration of the ethane is 2.98 percent, the molar concentrationof the propane is 2.90 percent, and the energy consumption of the gas per unit volume is 8.33 multiplied by 103kJ/Nm3The hydrogen-rich gas is separated by pressure swing adsorption to obtain high-purity hydrogen;
(4) the ethanol solution containing acetaldehyde is removed from the glow discharge electrolytic reactor, the ethanol solution is separated by a rectifying tower, the acetaldehyde comes out from the top of the rectifying tower, the acetaldehyde yield is 83.2 percent, and the ethanol and the water can be recycled after the ethanol and the water are discharged from a tower kettle and the conductivity and the concentration are adjusted.
Example 6: the tungsten-cerium alloy is used as the anode material of the glow discharge electrolysis reactor, and the ratio of the area of the anode electrode to the area of the cathode electrode is 1: 10000. The ethanol solution is electrolyzed by glow discharge to prepare acetaldehyde according to the following steps.
(1) Mixing ethanol and water at a volume ratio of 1: 10 to obtain a solution, adding sodium hydroxide as an auxiliary electrolyte, and adjusting the conductivity of the solution to 30000S.m-1；
(2) Putting the prepared ethanol solution into a glow discharge-containing electrolytic reactor, switching on a power supply, and carrying out anode glow discharge electrolysis with the electrolytic voltage of two poles of 200V; producing acetaldehyde, which is dissolved in the electrolyte;
(3) the hydrogen-rich gas coming out from the glow discharge electrolysis reactor is dried and purified to obtain hydrogen molar concentration74.16%, carbon monoxide molar concentration of 5.02%, methane molar concentration of 6.98%, ethane molar concentration of 4.64%, and propane molar concentration of 6.52%, wherein the gas energy consumption per unit volume is 64.45X 103kJ/Nm3The hydrogen-rich gas is separated by pressure swing adsorption to obtainHigh purity hydrogen;
(4) the ethanol solution containing acetaldehyde is removed from the glow discharge electrolytic reactor, the ethanol solution is separated by a rectifying tower, the acetaldehyde comes out from the top of the rectifying tower, the acetaldehyde yield is 68.3 percent, and the ethanol and the water can be recycled after the ethanol and the water are discharged from a tower kettle and the conductivity and the concentration are adjusted.
Claims (5)
1. A method for preparing acetaldehyde by ethanol solution glow discharge electrolysis is characterized by comprising the following steps:
(1) mixing ethanol and water according to the volume ratio of 1: 0-15 to form a solution, and adding electrolyte into the solution until the conductivity of the solution reaches 0.005-50000 S.m-1；
(2) Putting the solution prepared in the step (1) into a glow discharge electrolysis reactor containing a cathode and an anode, switching on a power supply, and producing acetaldehyde, wherein the glow discharge electrolysis voltage exceeds the glow discharge transition point voltage;
(3) separating and purifying the gas generated in the step (2) to obtain high-purity hydrogen;
(4) and (3) rectifying and separating the solution in the reactor in the step (2) to obtain acetaldehyde.
2. The method according to claim 1, wherein the power source is a high voltage DC power source or a high voltage DC pulse power source, and the output voltage is greater than or equal to 100V.
3. The method according to claim 1, wherein the material of the discharge electrode of the glow discharge electrolysis reactor is any one of tungsten, a tungsten-cerium alloy, platinum and a platinum alloy.
4. The method according to claim 1, wherein the ratio of the area of the cathode electrode to the area of the anode electrode in the glow discharge electrolysis reactor is 1: 1 to 10000 during cathode glow discharge in the glow discharge electrolysis reactor.
5. The method according to claim 1, wherein the ratio of the area of the anode electrode to the area of the cathode electrode in the glow discharge electrolysis reactor is 1: 0.8-10000 during the anode glow discharge of the glow discharge electrolysis reactor.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102424646A (en) * | 2011-10-27 | 2012-04-25 | 大连理工大学 | Ethanol conversion method |
| CN102492957A (en) * | 2011-12-15 | 2012-06-13 | 天津工业大学 | Method for preparing aldehydes or acids by selectively performing catalytic oxidation on alcohols by electro-catalysis membrane |
| CN102634815A (en) * | 2012-04-13 | 2012-08-15 | 天津工业大学 | Method for synthesizing tetrapion by electric catalytic membrane |
| CN103952717A (en) * | 2014-05-07 | 2014-07-30 | 北京化工大学 | Photoelectrochemical decomposition water and organic synthesis coupled cascade reaction design method |
| CN108139330A (en) * | 2015-09-24 | 2018-06-08 | 因诺科技阿尔伯塔有限公司 | Solution cathode glow discharging elemental analysis |
| CN114012102A (en) * | 2021-12-16 | 2022-02-08 | 西北师范大学 | Preparation method of Ag nano particles |
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2007
- 2007-08-14 CN CNA2007100297018A patent/CN101126163A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102424646A (en) * | 2011-10-27 | 2012-04-25 | 大连理工大学 | Ethanol conversion method |
| CN102492957A (en) * | 2011-12-15 | 2012-06-13 | 天津工业大学 | Method for preparing aldehydes or acids by selectively performing catalytic oxidation on alcohols by electro-catalysis membrane |
| CN102492957B (en) * | 2011-12-15 | 2014-07-09 | 天津工业大学 | Method for preparing aldehydes or acids by selectively performing catalytic oxidation on alcohols by electro-catalysis membrane |
| CN102634815A (en) * | 2012-04-13 | 2012-08-15 | 天津工业大学 | Method for synthesizing tetrapion by electric catalytic membrane |
| CN102634815B (en) * | 2012-04-13 | 2015-04-15 | 天津工业大学 | Method for synthesizing tetrapion by electric catalytic membrane |
| CN103952717A (en) * | 2014-05-07 | 2014-07-30 | 北京化工大学 | Photoelectrochemical decomposition water and organic synthesis coupled cascade reaction design method |
| CN108139330A (en) * | 2015-09-24 | 2018-06-08 | 因诺科技阿尔伯塔有限公司 | Solution cathode glow discharging elemental analysis |
| CN114012102A (en) * | 2021-12-16 | 2022-02-08 | 西北师范大学 | Preparation method of Ag nano particles |
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