CN1303252C - Process of preparing ethyl aldehydic acid by electrolyzing - Google Patents
Process of preparing ethyl aldehydic acid by electrolyzing Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 29
- 230000008569 process Effects 0.000 title description 11
- 239000002253 acid Substances 0.000 title 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 title 1
- HHLFWLYXYJOTON-UHFFFAOYSA-N glyoxylic acid Chemical compound OC(=O)C=O HHLFWLYXYJOTON-UHFFFAOYSA-N 0.000 claims abstract description 158
- LEQAOMBKQFMDFZ-UHFFFAOYSA-N glyoxal Chemical compound O=CC=O LEQAOMBKQFMDFZ-UHFFFAOYSA-N 0.000 claims abstract description 94
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 49
- 229940015043 glyoxal Drugs 0.000 claims abstract description 47
- 230000003647 oxidation Effects 0.000 claims description 6
- 238000007254 oxidation reaction Methods 0.000 claims description 6
- 238000000746 purification Methods 0.000 claims description 4
- 239000003792 electrolyte Substances 0.000 abstract description 7
- 230000001590 oxidative effect Effects 0.000 abstract description 4
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 10
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 9
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 229910052801 chlorine Inorganic materials 0.000 description 4
- 239000000460 chlorine Substances 0.000 description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 235000006408 oxalic acid Nutrition 0.000 description 3
- POJWUDADGALRAB-UHFFFAOYSA-N allantoin Chemical compound NC(=O)NC1NC(=O)NC1=O POJWUDADGALRAB-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000005341 cation exchange Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- POJWUDADGALRAB-PVQJCKRUSA-N Allantoin Natural products NC(=O)N[C@@H]1NC(=O)NC1=O POJWUDADGALRAB-PVQJCKRUSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZNZYKNKBJPZETN-WELNAUFTSA-N Dialdehyde 11678 Chemical compound N1C2=CC=CC=C2C2=C1[C@H](C[C@H](/C(=C/O)C(=O)OC)[C@@H](C=C)C=O)NCC2 ZNZYKNKBJPZETN-WELNAUFTSA-N 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 229960000458 allantoin Drugs 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- -1 chlorine ions Chemical class 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- MWOOGOJBHIARFG-UHFFFAOYSA-N vanillin Chemical compound COC1=CC(C=O)=CC=C1O MWOOGOJBHIARFG-UHFFFAOYSA-N 0.000 description 1
- FGQOOHJZONJGDT-UHFFFAOYSA-N vanillin Natural products COC1=CC(O)=CC(C=O)=C1 FGQOOHJZONJGDT-UHFFFAOYSA-N 0.000 description 1
- 235000012141 vanillin Nutrition 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Description
技术领域technical field
本发明涉及乙醛酸的制备方法，尤其涉及电解乙二醛制备乙醛酸的方法。The invention relates to a preparation method of glyoxylic acid, in particular to a method for preparing glyoxylic acid by electrolyzing glyoxal.
背景技术Background technique
乙醛酸(CHOCOOH)是一种重要的化工原料，其可用于制备香兰素、尿囊素等精细化工产品。电解制备乙醛酸的方法分为阳极氧化法(CN1318653A)和阴极还原法(美国专利3,779,875和CN1281063A)。现有技术中存在的不足是，电解的电流效率及产品(乙醛酸)的选择性不高，尚有改进余地。Glyoxylic acid (CHOCOOH) is an important chemical raw material, which can be used to prepare fine chemical products such as vanillin and allantoin. The method for preparing glyoxylic acid by electrolysis is divided into anodic oxidation method (CN1318653A) and cathodic reduction method (US Patent No. 3,779,875 and CN1281063A). The deficiencies in the prior art are that the current efficiency of electrolysis and the selectivity of the product (glyoxylic acid) are not high, and there is still room for improvement.
发明内容Contents of the invention
本发明的目的在于，提供一种采用脉冲电流的方式进行电解乙二醛制备乙醛酸的方法，以提高电解过程的电流效率和乙醛酸的化学选择性。The object of the present invention is to provide a method for preparing glyoxylic acid by electrolyzing glyoxal in a pulse current mode, so as to improve the current efficiency of the electrolysis process and the chemoselectivity of glyoxylic acid.
本发明的构思是这样的：Design of the present invention is such:
由于在乙二醛和盐酸混合物阳极液电解氧化制备乙醛酸过程中，发生的氧化还原反应为：盐酸酸根氯离子首先在阳极上被氧化为具有强氧化性的氯分子，氯分子再与原料乙二醛发生氧化还原反应将乙二醛氧化为乙醛酸。阳极电解反应式为：Because in the process of preparing glyoxylic acid by electrolytic oxidation of the anolyte of the mixture of glyoxal and hydrochloric acid, the oxidation-reduction reaction is as follows: the chloride ion of hydrochloric acid is first oxidized to chlorine molecules with strong oxidizing properties on the anode, and the chlorine molecules are then combined with the raw materials. Glyoxal undergoes a redox reaction to oxidize glyoxal to glyoxylic acid. The anode electrolysis reaction formula is:
在电解过程中由于氯分子与乙二醛的反应速率较慢。当持续地向电极通电时，部分氯气没有能够与乙二醛及时反应生成产品乙醛酸而逸出阳极液，从而导致电流效率下降。而采用时而通电，时而断电的脉冲电解法能够减少氯气逸出阳极液，尽可能地促进电解产生的氯气与乙二醛完全反应生成乙醛酸。从而提高电解过程的电流效率。During the electrolysis process, the reaction rate between chlorine molecules and glyoxal is relatively slow. When the electrode is continuously energized, part of the chlorine gas fails to react with glyoxal in time to form the product glyoxylic acid and escapes from the anolyte, resulting in a decrease in current efficiency. And the pulse electrolysis method that adopts power-on sometimes and power-off sometimes can reduce chlorine gas from escaping from the anolyte, and promote the complete reaction of chlorine gas produced by electrolysis with glyoxal to generate glyoxylic acid as much as possible. Thereby improving the current efficiency of the electrolysis process.
电解后期，阳极液中乙醛酸含量比乙二醛含量高得多，如果此时仍然采用现有的持续通电的恒电流电解法，电解产生的大量氯气会将目的产品乙醛酸继续氧化为草酸，这样也会降低电解过程的电流效率和乙醛酸的选择性。而采用脉冲电解法能够大幅度地降低阳极液中氯气的含量，降低氯气与乙醛酸的结合，从而提高了电解过程的乙醛酸选择性。In the later stage of electrolysis, the content of glyoxylic acid in the anolyte is much higher than that of glyoxal. If the existing constant current electrolysis method with continuous power is still used at this time, a large amount of chlorine gas generated by electrolysis will continue to oxidize the target product glyoxylic acid to Oxalic acid, which will also reduce the current efficiency of the electrolysis process and the selectivity of glyoxylic acid. However, the pulse electrolysis method can greatly reduce the content of chlorine gas in the anolyte, reduce the combination of chlorine gas and glyoxylic acid, thereby improving the glyoxylic acid selectivity in the electrolysis process.
根据上述构思，本发明提出了如下所述的技术方案：According to above-mentioned design, the present invention proposes the technical scheme as follows:
本发明所说的电解制备乙醛酸的方法包括：乙二醛阳极电解氧化制备乙醛酸和乙醛酸初产品的提纯两个步骤，其中电解液的初始组成、电解液的电极表观流速、电解液温度、电极参数及乙醛酸初产品的提纯方法均为现有技术，参见美国专利4,235,684、CN1083871A及CN1318653A等，其特征在于，所说的电解采用的脉冲恒电流或变电流的方式进行，其中：The method for preparing glyoxylic acid by electrolysis in the present invention comprises two steps: glyoxylic acid is prepared by anodic electrolytic oxidation of glyoxal and the purification of the initial product of glyoxylic acid, wherein the initial composition of the electrolyte, the electrode superficial flow rate of the electrolyte , electrolyte temperature, electrode parameters and the purification method of glyoxylic acid primary product are all prior art, referring to U.S. Patent 4,235,684, CN1083871A and CN1318653A etc., it is characterized in that, the pulse constant current or variable current mode that said electrolysis adopts proceed, where:
(1)脉冲电解的脉冲频率f为0.01～100Hz；(1) The pulse frequency f of pulse electrolysis is 0.01～100Hz;
(2)脉冲载空比值为：0.01～100；(2) Pulse load-to-empty ratio: 0.01~100;
(3)脉冲波形为方波，通电时的电流为恒电流或变电流；(3) The pulse waveform is a square wave, and the current when electrified is a constant current or a variable current;
当脉冲电流为恒电流时，其表观电流密度范围为：200～5000A/m2；When the pulse current is a constant current, the apparent current density range is: 200-5000A/m 2 ;
当脉冲电流为变电流时，电流的变化方案为：When the pulse current is a variable current, the change scheme of the current is:
①乙醛酸浓度与乙二醛浓度比：0～6∶1 I① Ratio of glyoxylic acid concentration to glyoxal concentration: 0～6:1 I
②乙醛酸浓度与乙二醛浓度比：6∶1～40∶3 α×I②The ratio of glyoxylic acid concentration to glyoxal concentration: 6:1～40:3 α×I
式中：浓度为质量百分浓度，I为表观电流密度，其范围为：200～5000A/m2，α＝0.3～0.9，最佳为0.5～0.9。In the formula: the concentration is the mass percent concentration, I is the apparent current density, and its range is: 200-5000A/m 2 , α=0.3-0.9, and the best is 0.5-0.9.
优选的技术方案是：电解中所用的阳极为固定床阳极，其参数参见CN1318653A，电解采用脉冲变电流方式进行，电流的变化方案为：The preferred technical scheme is: the anode used in the electrolysis is a fixed bed anode, its parameters refer to CN1318653A, the electrolysis is carried out in a pulse variable current mode, and the current variation scheme is:
①乙醛酸浓度与乙二醛浓度比：0～6∶1 I① Ratio of glyoxylic acid concentration to glyoxal concentration: 0～6:1 I
②乙醛酸浓度与乙二醛浓度比：6∶1～40∶3 α×I②The ratio of glyoxylic acid concentration to glyoxal concentration: 6:1～40:3 α×I
式中：浓度为质量百分浓度，I为表观电流密度，其范围为：200～5000A/m2，α＝0.5～0.9。In the formula: the concentration is the mass percent concentration, I is the apparent current density, and its range is: 200-5000A/m 2 , α=0.5-0.9.
按上述技术方案所获得的含有乙醛酸的阳极电解液初产品无需分离出乙二醛，只需经现有的减压蒸发后即可获得符合要求(乙醛酸含量≥40.0％，乙二醛含量≤3.0％)的乙醛酸产品。The initial product of the anolyte solution containing glyoxylic acid obtained by the above-mentioned technical scheme does not need to separate glyoxal, and only needs to be obtained after the existing decompression evaporation to meet the requirements (glyoxylic acid content ≥ 40.0%, glyoxal Glyoxylic acid products with aldehyde content ≤ 3.0%.
具体实施方式Detailed ways
本发明所说的电解制备乙醛酸的方法包括如下步骤：The method for preparing glyoxylic acid by electrolysis in the present invention comprises the steps:
1、乙二醛的阳极电解氧化：1. Anodic electrolytic oxidation of glyoxal:
将乙二醛、盐酸和去离子水一次性加入阳极混合槽中，组成阳极电解液。将20％的硫酸水溶液一次性加入阴极混合槽中，形成阴极电解液。用泵将阳极液和阴极液分别送入具有阳离子交换膜的固定床阳极电解槽中进行脉冲电解反应。含有反应生成的乙醛酸的阳极电解液被送回阳极混合槽，然后再被送入电解槽进行电解反应，如此多次循环，直至阳极初产品中乙醛酸的浓度与乙二醛浓度比达到40∶3，停止电解。Add glyoxal, hydrochloric acid and deionized water into the anode mixing tank at one time to form the anolyte. Add 20% sulfuric acid aqueous solution to the cathode mixing tank at one time to form catholyte. The anolyte and catholyte are sent to the fixed-bed anode electrolyzer with cation exchange membrane respectively by pump to carry out the pulse electrolysis reaction. The anolyte containing the glyoxylic acid produced by the reaction is sent back to the anode mixing tank, and then sent to the electrolytic tank for electrolysis reaction, so many cycles, until the concentration of glyoxylic acid in the initial product of the anode is higher than the concentration of glyoxal When 40:3 was reached, the electrolysis was stopped.
研究发现在乙二醛阳极氧化制备乙醛酸过程中，不断地有氯气从阳极电解液中逸出。由于氯气是由盐酸的氯离子在阳极上氧化而来的，且电解生成的氯气又充当电解氧化乙二醛合成乙醛酸的氧化剂。因此当有氯气从阳极液中逸出时，部分电能没有能够用于乙醛酸的合成，即电解过程的电流效率下降。为了减少氯气的逸出，本发明采用间歇性地向阴阳极通电并不断地降低电流密度的方法，即脉冲变电流电解法，使电解产生的多余的氯气在不通电时与原料乙二醛充分反应。从而提高氯气的利用率即电解过程的电流效率。在电解后期，由于阳极液中乙醛酸浓度高，而乙二醛含量很低，电解产生的大量氯气能够将产品乙醛酸进一步氧化为草酸。导致电解过程的电流效率和乙醛酸的化学选择性大大下降。采用脉冲变电流电解法能够大幅度地降低氯气的产生量，在保证尽可能多的乙二醛被氧化为乙醛酸的情况下能够减少乙醛酸被继续氧化为草酸的机会。本发明采用的脉冲变电流电解方式为：The study found that during the anodic oxidation of glyoxal to prepare glyoxylic acid, chlorine gas escaped from the anolyte continuously. Since chlorine gas is oxidized on the anode by chlorine ions of hydrochloric acid, and the electrolytically generated chlorine gas acts as an oxidant for electrolytically oxidizing glyoxal to synthesize glyoxylic acid. Therefore, when chlorine gas escapes from the anolyte, part of the electric energy cannot be used for the synthesis of glyoxylic acid, that is, the current efficiency of the electrolysis process decreases. In order to reduce the escape of chlorine gas, the present invention adopts the method of intermittently energizing the cathode and anode and continuously reducing the current density, that is, the pulse variable current electrolysis method, so that the excess chlorine gas produced by electrolysis can be fully mixed with the raw material glyoxal when no power is applied. reaction. Thereby improving the utilization rate of chlorine gas, that is, the current efficiency of the electrolysis process. In the later stage of electrolysis, due to the high concentration of glyoxylic acid in the anolyte and the low content of glyoxal, a large amount of chlorine gas generated by electrolysis can further oxidize the product glyoxylic acid to oxalic acid. As a result, the current efficiency of the electrolysis process and the chemoselectivity of glyoxylic acid are greatly reduced. The pulse variable current electrolysis method can greatly reduce the production of chlorine gas, and can reduce the chance of glyoxylic acid being further oxidized to oxalic acid while ensuring that as much glyoxal is oxidized to glyoxylic acid. The pulse variable current electrolysis mode that the present invention adopts is:
(1)脉冲电解的脉冲频率f为0.01～100Hz；(1) The pulse frequency f of pulse electrolysis is 0.01～100Hz;
(2)脉冲载空比值范围为：0.01～100；(2) The range of pulse load-to-empty ratio is: 0.01～100;
(3)脉冲波形为方波，通电时的电流变电流，电流的变化方案为：(3) The pulse waveform is a square wave, the electrorheological current when the power is turned on, and the change scheme of the current is:
当0≤乙醛酸浓度与乙二醛浓度比≤6∶1时为 I，When the ratio of 0≤glyoxylic acid concentration to glyoxal concentration≤6:1 is I,
当6∶1＜乙醛酸浓度与乙二醛浓度比≤40∶3为 α×I，When the ratio of 6:1<glyoxylic acid concentration to glyoxal concentration≤40:3 is α×I,
式中：浓度为质量百分比，I为表观电流密度，其范围为：200～5000A/m2，α＝0.5～0.9。In the formula: the concentration is the mass percentage, I is the apparent current density, and its range is: 200-5000A/m 2 , α=0.5-0.9.
2、乙醛酸初产品的提纯2. Purification of the initial product of glyoxylic acid
上述含有乙醛酸的阳极电解液初产品无需分离出乙二醛，只需采用现有的减压蒸发后即可获得符合要求(乙醛酸含量≥40.0％，乙二醛含量≤3.0％)的乙醛酸商品。The initial product of the above-mentioned anolyte containing glyoxylic acid does not need to separate glyoxal, and only needs to adopt the existing reduced-pressure evaporation to obtain a product that meets the requirements (glyoxylic acid content ≥ 40.0%, glyoxal content ≤ 3.0%) glyoxylic acid products.
本发明具有如下优点：The present invention has the following advantages:
由于采用脉冲电解法，使得阳极初产品中乙醛酸含量与乙二醛含量比达到40∶3，而且整个电解过程具有极高的电流效率和乙醛酸选择性。Due to the adoption of the pulse electrolysis method, the ratio of glyoxylic acid content to glyoxal content in the initial anode product reaches 40:3, and the entire electrolysis process has extremely high current efficiency and glyoxylic acid selectivity.
本发明所涉及到的电流效率和乙醛酸化学选择性的定义为：The definition of current efficiency involved in the present invention and glyoxylic acid chemoselectivity is:
电流效率＝生成单位摩尔乙醛酸消耗的理论电量/生成单位摩尔乙醛酸实际消耗的电量Current efficiency = Theoretical electricity consumed to generate unit mole of glyoxylic acid/actual electricity consumed to generate unit mole of glyoxylic acid
乙醛酸选择性＝乙醛酸的生成量(mol)/消耗的乙二醛量(mol)。Glyoxylic acid selectivity = the amount of glyoxylic acid produced (mol)/the amount of glyoxal consumed (mol).
下面通过实施例对本发明作进一步的说明，其目的在于更好理解本发明的内容。因此，本发明的保护范围不受所举之例的限制。此外，实施例中的所有百分含量均为质量百分含量。The present invention is described further below by embodiment, and its purpose is to better understand content of the present invention. Therefore, the protection scope of the present invention is not limited by the examples given. In addition, all percentages in the examples are percentages by mass.
实施例1Example 1
用纯度99.99％的平板铅作阴极。固定床阳极厚度为25毫米。电极表观面积为0.02m2。用CM001型阳离子交换膜作隔膜。电解开始时阳极电解液中乙二醛浓度7％、盐酸浓度8％。阴极液为20％的硫酸水溶液。用磁力泵作动力对电解液进行循环操作，阴、阳极液的电极表观流速均为0.3米/秒。阳极电解液温度为32±1℃。脉冲电解的载空比值为10，脉冲频率f＝0.2Hz，通电时的电极表观电流密度2000A/m2。电解结果为：电流效率为76.4％，乙醛酸选择性为87.5％。阳极初产品中乙醛酸含量为8.5％，乙二醛含量为0.61％，乙醛酸含量与乙二醛含量比值为13.9。Use flat lead with a purity of 99.99% as the cathode. The thickness of the fixed bed anode is 25 mm. The apparent area of the electrode is 0.02 m 2 . Use CM001 type cation exchange membrane as diaphragm. At the beginning of electrolysis, the concentration of glyoxal in the anolyte was 7%, and the concentration of hydrochloric acid was 8%. Catholyte is 20% sulfuric acid aqueous solution. A magnetic pump is used as power to circulate the electrolyte, and the superficial flow velocity of the electrodes of the cathode and anode liquids is both 0.3 m/s. The anolyte temperature was 32±1°C. The duty-to-empty ratio of the pulse electrolysis is 10, the pulse frequency f=0.2 Hz, and the apparent current density of the electrode when electrified is 2000 A/m 2 . The results of electrolysis are: the current efficiency is 76.4%, and the glyoxylic acid selectivity is 87.5%. The glyoxylic acid content in the primary anode product is 8.5%, the glyoxal content is 0.61%, and the ratio of the glyoxylic acid content to the glyoxal content is 13.9.
实施例2Example 2
采用与实施例1相同的装置和阳极电解液。其中脉冲载空比值为1，脉冲频率f＝0.2Hz。通电时的电极表观电流密度为2000A/m2。电解结果为：电流效率为84.2％，乙醛酸选择性为92.7％。阳极初产品中乙醛酸含量为8.7％，乙二醛含量为0.59％，乙醛酸含量与乙二醛含量比值为14.7。The same apparatus and anolyte as in Example 1 were used. Among them, the pulse load-to-empty ratio is 1, and the pulse frequency f=0.2Hz. The electrode apparent current density at the time of energization was 2000 A/m 2 . The results of electrolysis are: the current efficiency is 84.2%, and the glyoxylic acid selectivity is 92.7%. The glyoxylic acid content in the primary anode product is 8.7%, the glyoxal content is 0.59%, and the ratio of the glyoxylic acid content to the glyoxal content is 14.7.
实施例3Example 3
采用与实施例1相同的装置和阳极电解液。其中脉冲载空比值为1，脉冲频率f＝5Hz。通电时的电极表观电流密度为2000A/m2。电解结果为：电流效率为80.7％，乙醛酸选择性为89.3％。阳极初产品中乙醛酸含量为8.6％，乙二醛含量为0.60％，乙醛酸含量与乙二醛含量比值为14.3。The same apparatus and anolyte as in Example 1 were used. Among them, the pulse load-to-empty ratio is 1, and the pulse frequency f=5Hz. The electrode apparent current density at the time of energization was 2000 A/m 2 . The results of electrolysis are: the current efficiency is 80.7%, and the glyoxylic acid selectivity is 89.3%. The glyoxylic acid content in the primary anode product is 8.6%, the glyoxal content is 0.60%, and the ratio of the glyoxylic acid content to the glyoxal content is 14.3.
实施例4Example 4
采用与实施例1相同的装置和阳极电解液。其中脉冲载空比值为1，脉冲频率f＝0.2Hz。当阳极液中乙醛酸浓度与乙二醛浓度比为[0，6∶1]时，脉冲电流密度为：2000A/m2；当阳极液中乙醛酸浓度与乙二醛浓度比为(6∶1，40∶3]时，电流密度：1000A/m2。电解结果为：电流效率为87.4％，乙醛酸选择性为94.0％。阳极初产品中乙醛酸含量为8.9％，乙二醛含量为0.57％，乙醛酸含量与乙二醛含量比值为15.6。The same apparatus and anolyte as in Example 1 were used. Among them, the pulse load-to-empty ratio is 1, and the pulse frequency f=0.2Hz. When the ratio of glyoxylic acid concentration to glyoxal concentration in the anolyte is [0,6:1], the pulse current density is: 2000A/m 2 ; when the ratio of glyoxylic acid concentration to glyoxal concentration in the anolyte is ( 6:1, 40:3], the current density: 1000A/m 2 . The electrolysis result is: the current efficiency is 87.4%, and the glyoxylic acid selectivity is 94.0%. The content of glyoxylic acid in the initial product of the anode is 8.9%. The dialdehyde content is 0.57%, and the ratio of glyoxylic acid content to glyoxal content is 15.6.
对比例Comparative ratio
采用与实施例1相同的装置和阳极电解液。采用恒电流电解。电解表观电流密度为2000A/m2。电解结果为：电流效率为69.8％，乙醛酸选择性为76.5％。阳极初产品中乙醛酸含量为8.2％，乙二醛含量为0.61％，乙醛酸含量与乙二醛含量比值为13.4。The same apparatus and anolyte as in Example 1 were used. Using constant current electrolysis. The apparent current density of electrolysis is 2000A/m 2 . The results of electrolysis are: the current efficiency is 69.8%, and the glyoxylic acid selectivity is 76.5%. The glyoxylic acid content in the initial anode product is 8.2%, the glyoxal content is 0.61%, and the ratio of the glyoxylic acid content to the glyoxal content is 13.4.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4217336A1 (en) * | 1992-05-26 | 1993-12-02 | Hoechst Ag | Glyoxylic acid prodn. by electrochemical redn. of oxalic acid |
| EP0578946A2 (en) * | 1992-05-26 | 1994-01-19 | Hoechst Aktiengesellschaft | Electrochemical process for reducing oxatic acid to glyoxylic acid |
| CN1318653A (en) * | 2001-04-17 | 2001-10-24 | 华东理工大学 | Method for synthesizing glyoxylic acid by electrolytic oxidation of glyoxal |
| CN1322859A (en) * | 2001-04-17 | 2001-11-21 | 华东理工大学 | Paired electrolysis procss of preparing glyoxalic acid |
| CN1322860A (en) * | 2001-04-17 | 2001-11-21 | 华东理工大学 | Oxalic acid electroreduction process of preparing glyoxalic acid |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4217336A1 (en) * | 1992-05-26 | 1993-12-02 | Hoechst Ag | Glyoxylic acid prodn. by electrochemical redn. of oxalic acid |
| EP0578946A2 (en) * | 1992-05-26 | 1994-01-19 | Hoechst Aktiengesellschaft | Electrochemical process for reducing oxatic acid to glyoxylic acid |
| CN1318653A (en) * | 2001-04-17 | 2001-10-24 | 华东理工大学 | Method for synthesizing glyoxylic acid by electrolytic oxidation of glyoxal |
| CN1322859A (en) * | 2001-04-17 | 2001-11-21 | 华东理工大学 | Paired electrolysis procss of preparing glyoxalic acid |
| CN1322860A (en) * | 2001-04-17 | 2001-11-21 | 华东理工大学 | Oxalic acid electroreduction process of preparing glyoxalic acid |
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