Method and device for synthesizing glyoxylic acid

Abstract

The invention discloses a synthesis method and device of glyoxylic acid. The synthesis method of glyoxylic acid adopts the synthesis device of glyoxylic acid for continuous operation, is short in retention time and large in treatment capacity, remarkably improves the synthesis rate of glyoxylic acid, and greatly improves the space time yield. A glyoxylic acid synthesis device is used, a good mixing environment is provided for mixing of raw materials, and the utilization rate of the raw materials is increased; meanwhile, the reaction process can be accurately controlled, the use amount of nitric acid is reduced, excessive oxidation is prevented, and byproducts are reduced; in addition, the feeding is more dispersed, the bumping phenomenon caused by overhigh local concentration is avoided, and the stable and sufficient reaction is ensured. The synthesis method of glyoxylic acid is low in production cost and high in yield.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial production of glyoxylic acid, and in particular to a method and device for synthesizing glyoxylic acid. Background Art

[0002] Glyoxylic acid is the simplest aldehyde acid, possessing both aldehyde and carboxyl groups, and possessing the dual properties of an aldehyde and an acid. It is widely distributed in nature in animals and plants and participates in metabolism. Glyoxylic acid is an important chemical raw material and organic synthesis intermediate, widely used in fragrances, medicine, and agriculture. In the fragrance industry, glyoxylic acid is primarily used to synthesize vanillin. In medicine, it is used to synthesize mandelic acid and allantoin. In agriculture, it is used in the production of diphenylacetic acid and glyphosate. The synthesis and application of glyoxylic acid are attracting increasing attention.

[0003] A variety of methods for synthesizing glyoxylic acid have been reported. In 1993, Ochoa et al. (Ochoa JR, De Diego A, Santa-Olalla J. Electrosynthesis of glyoxylic acid using a continuously electrogenerated lead cathode [J]. Journal of applied electrochemistry, 1993, 23(9): 905-909.) reported synthesizing glyoxylic acid using oxalic acid electrolytic reduction. However, this method suffers from problems such as poor product quality, high energy consumption, and high investment and production costs.

[0004] In 2006, Sun et al. (Sun ZC, Eli W, Xu TY, et al. Oxidation of glyoxal with hydroperoxide compounds prepared from maleic acid by ozonation to produce glyoxylic acid [J]. Industrial & Engineering Chemistry Research, 2006, 45(6): 1849-1852.) reported the synthesis of glyoxylic acid by the ozonation of maleic acid. Maleic acid was ozonolyzed in a solvent containing methanol, acetic acid, or formic acid at approximately -5°C to form hydroperoxide compounds and glyoxylic acid hemiacetal in high yield. This solution was then added to a glyoxal solution at approximately 38°C. The glyoxal was oxidized by the hydroperoxide compounds in the mixture via a Baeyer-Villiger rearrangement to obtain the target product, glyoxylic acid. However, this method is complex, requires large investment, and consumes high energy.

[0005] Sui et al. (Sui X, Zhou Y, Zhang F, et al. Deciphering the aqueous chemistry of glyoxal oxidation with hydrogen peroxide using molecular imaging [J]. Physical Chemistry Chemical Physics, 2017, 19 (31): 20357-20366.) reported in 2017 the synthesis of glyoxalic acid by hydrogen peroxide oxidation. However, hydrogen peroxide in this method is easily decomposed by heat, and the reaction temperature needs to be strictly controlled.

[0006] Patent CN106431885B discloses a method for synthesizing glyoxylic acid using ozonation of a mixed solvent containing maleic anhydride. The raw materials undergo hydrolysis, ozonation, reduction, vacuum distillation, and crystallization to produce solid glyoxylic acid. However, this method is time-consuming, complex, and poses serious environmental risks.

[0007] Patent US4235684A uses Cl2 as a medium to electrochemically oxidize glyoxal to glyoxylic acid by an indirect oxidation method. The current efficiency is 67-85% and the yield is 66-82%. However, the current density is too low and the reaction cycle is too long, requiring a reaction time of more than 100 hours, resulting in high production costs.

[0008] Patent CN114763320B discloses a method for producing glyoxylic acid by catalytic oxidation of glyoxal using N2O as an oxidant in the presence of a catalyst composed of a mixture of Fe / SAPO molecular sieve and Mn / TS-1 molecular sieve. This method also suffers from the problems of long time consumption and low yield.

[0009] Patent CN113789529B discloses a method for photoelectrocatalytic oxidation of glyoxal to glyoxylic acid. This method uses an electrolytic cell with two electrodes, a cation and anode, separated by a cationic membrane. WO3, TiO2, or BiVO4 semiconductor materials serve as the anode and graphite carbon materials serve as the cathode. Under conditions of light radiation and applied bias voltage, an inorganic acid solution containing glyoxal is photoelectrocatalytically oxidized to synthesize glyoxylic acid. This method requires a synthesis time of 2 to 16 hours.

[0010] Traditional methods for synthesizing glyoxylic acid have problems such as long production time, low yield, harsh reaction conditions, complex processes, large investments, and high energy consumption, which result in slow synthesis and high costs, hindering the industrialization and commercialization of glyoxylic acid. Summary of the Invention

[0011] In order to overcome the problem of low time and space efficiency in the production of glyoxylic acid in the prior art, the present invention aims to provide a method and apparatus for synthesizing glyoxylic acid.

[0012] To achieve the above object, the technical solution adopted by the present invention is:

[0013] A glyoxylic acid synthesis device comprises a first joint, a second joint, an outer tube and an inner tube. The first joint is provided with a feed inlet on the top, and a feed outlet is provided at one end of the second joint. The outer tube is provided between the first and second joints, and the inner tube is provided inside the outer tube. One end of the inner tube passes through the outer tube, while the other end does not pass through the outer tube. An inlet is provided at the front end of the inner tube near the first joint, and a rear end of the inner tube near the second joint is sealed. A plurality of plug-ins are sleeved on the outer wall of the inner tube, and the plug-ins are provided with guide vanes. The guide vanes are arranged in a spiral shape. Distribution holes are provided on the outer wall of the inner tube and between adjacent guide vanes.

[0014] Furthermore, a fixing ring for fixing the guide vane is provided on the plug-in.

[0015] Furthermore, the number of guide vanes is 2-12.

[0016] Furthermore, the guide vane is curved, and the bending angle is 30-120°.

[0017] Furthermore, the distribution holes are circular, and the diameters of the distribution holes are equal or the diameters of the distribution holes increase gradually along the axial direction of the inner tube 5 .

[0018] Furthermore, the diameter of the distribution holes increases by 0.1-2 mm along the flow direction.

[0019] A method for synthesizing glyoxylic acid comprises the following steps:

[0020] The nitric acid solution is injected from the inlet, flows through the inner tube and then sprayed into the outer tube through the distribution hole. The initiator glyoxal solution is injected into the outer tube from the feed port. The initiator glyoxal solution reacts with the nitric acid solution to generate glyoxylic acid.

[0021] Furthermore, the mass concentration of the nitric acid solution is 30%-60, and the initiator is sodium nitrite.

[0022] Furthermore, the molar ratio of nitric acid to glyoxal is 1-5:1, and the molar ratio of initiator to glyoxal is 0-0.5:1.

[0023] Furthermore, the reaction temperature is 25-80° C. and the reaction time is 5-10 min.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The glyoxylic acid synthesis device of the present invention has a spiral guide vane on the plug-in. The guide vane can change the flow direction and path of the fluid, forming a complex flow pattern within the reactor and increasing the contact area and frequency between different fluids, thereby greatly improving the mixing effect and allowing the reactants to mix more fully and evenly. This improves the raw material utilization rate and is conducive to improving the selectivity and conversion rate of the reaction. The spiral guide vane also enhances the mass and heat transfer performance of the fluid. The glyoxylic acid synthesis device of the present invention provides a good mixing environment for mixing the raw materials, improving the utilization rate of the raw materials. At the same time, it can precisely control the reaction process, reduce the amount of nitric acid used, prevent excessive oxidation, and reduce the production of by-products. In addition, it makes the feed more dispersed, avoids the occurrence of bumping caused by excessively high local concentrations, and ensures a stable and sufficient reaction. The glyoxylic acid synthesis method of the present invention has low production cost and high yield.

[0026] Furthermore, combined with the flow-guiding function of the plug-in, adaptive adjustment of the fluid flow rate and injection volume is formed, and the final concentration balance of the main reactant is achieved through the large-aperture distribution hole close to the second joint. The initial addition of trace components is accurately controlled through the small-aperture distribution hole close to the first joint to avoid side reactions caused by local concentration mutations.

[0027] Furthermore, the distribution holes opened on the inner tube gradually increase in diameter along the flow direction (from inlet to outlet), realizing progressive distribution of the reaction fluid along the axial length, realizing the distribution function along the process, reducing fluid resistance and improving mixing efficiency.

[0028] The method for synthesizing glyoxylic acid of the present invention uses a glyoxylic acid synthesis device for continuous operation, has a short residence time, and a large processing capacity, thereby significantly improving the synthesis rate of glyoxylic acid and greatly improving the space-time yield. The method for synthesizing glyoxylic acid of the present invention is continuous synthesis, has mild conditions, a fast production speed, can be synthesized in large quantities, and has good reproducibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of the synthesis device of glyoxylic acid;

[0030] Figure 2 This is a simplified structural diagram of the synthesis device for glyoxylic acid;

[0031] Figure 3 Schematic diagram of the inner tube and the plug-in structure on the inner tube;

[0032] Figure 4 This is a schematic diagram of the plug-in structure;

[0033] Figure 5 It is the HPLC chromatogram of Example 1;

[0034] Figure 6 It is the HPLC chromatogram of Example 2;

[0035] Figure 7 It is the HPLC chromatogram of Example 3;

[0036] Figure 8 It is the HPLC chromatogram of Example 4;

[0037] Figure 9 Flow chart for the synthesis of glyoxylic acid.

[0038] In the figure, 1 is the first joint, 2 is the second joint, 3 is the feed port, 4 is the outer tube, 5 is the inner tube, 6 is the plug-in, 7 is the guide plate, 8 is the discharge port, 9 is the distribution hole, and 10 is the fixing ring. DETAILED DESCRIPTION

[0039] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in a variety of different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0040] A method for synthesizing glyoxylic acid of the present invention comprises the following steps:

[0041] Step 1, preparing a nitric acid solution with a mass concentration of 30%-60% as solution A;

[0042] Step 2: adding an initiator (sodium nitrite) to the glyoxal solution and stirring to dissolve it to obtain solution B; wherein the molar ratio of sodium nitrite to glyoxal is 0-0.5:1.

[0043] In step 3, solution A and solution B are added to the inner tube and outer ring system of a glyoxylic acid synthesis device, respectively. The two are reacted in the outer ring system at 25-80°C for 5-10 minutes. After the reaction, a mixture is obtained, and the mixture is detected and separated using high performance liquid chromatography to obtain the target product, glyoxylic acid. The molar ratio of nitric acid to glyoxal is 1-5:1.

[0044] See also Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 9A synthesis device for glyoxylic acid in the present invention includes a first joint 1, a second joint 2, an outer tube 4 and an inner tube 5. A feed port 3 is provided on the upper portion of the first joint 1, and a discharge port 8 is provided at one end of the second joint 2. An outer tube 4 is provided between the first joint 1 and the second joint 2, and an inner tube 5 is provided inside the outer tube 4. The inner tube 5 runs through the entire outer tube 4 to form a sleeve structure. One end of the inner tube 5 passes through the outer tube 4, and the other end does not pass through the outer tube 4. The front end of the inner tube 5 near the first joint 1 is a feed port 3, and the rear end of the inner tube 5 near the second joint 2 is airtight. A number of plug-ins 6 are sleeved on the outer wall of the inner tube 5, and each plug-in 6 is provided with two fixed rings 10 and 2-12 spiral guide plates 7. The guide plates 7 are fixed by the fixed rings 10. The guide plates 7 are spirally arranged along the circumference of the inner tube 5. The guide plates 7 present a continuous and regular curved shape with a bending angle of 30-120°. Starting from one end of the plug-in 6, the guide plates gradually extend along the inner tube 5 to the plug-in. At the end of the component 6, a spiral path is formed, and the rotation direction of the guide plate 7 forms a specific angle with the flow direction of the fluid, which can induce the fluid to produce three-dimensional spiral motion. Circular distribution holes 9 are provided on the outer wall of the inner tube 5 and between adjacent guide plates 7. The aperture of the distribution hole 9 changes gradiently along the flow direction of the fluid, specifically: the aperture of the distribution holes is equal or the aperture of the distribution holes 9 increases gradiently along the flow direction. Through the precisely designed hole group distribution parameters (including aperture 0.2-2mm, hole spacing 10-300mm), the progressive distribution of the reaction fluid in the axial length is realized. The number of guide plates 7 corresponds to the number of distribution holes 9 opened on the inner tube 5. Specifically, a distribution hole 9 is opened between two guide plates 7, and the distribution holes 9 are distributed along the inner tube 5 to realize the function of distribution along the process.

[0045] The diameter of the inner tube 5 is 0.2-20 mm, the diameter of the outer tube 4 is 0.8-30 mm, and the outer ring gap (the distance between the inner tube 5 and the outer tube 4) is 0.6-20 mm; the inner tube 5 is provided with distribution holes 9, the diameter of the distribution holes 9 is 0.2-2 mm, the interval between adjacent distribution holes 9 is 10-300 mm, the number of distribution holes 9 is 1-12, and the distribution holes 9 are distributed along the axial direction of the inner tube 5.

[0046] Each plug-in 6 is composed of two fixed rings 10 at the front and rear ends and 2-12 spiral guide vanes 7 rotating around a central axis, forming a cylindrical whole. The guide vanes 7 spirally extend from the front end of the plug-in 6 (the end close to the first connector 1) to the rear end of the plug-in 6 (the end where the fluid flows out). The starting point and end point of the guide vanes 7 are firmly fixed at both ends of the plug-in 6 (the front and rear ends), presenting an orderly spiral arrangement. The guide vanes 7 have a certain bending angle (30-120°), and the bending angle of each guide vane 7 is consistent, ensuring that the fluid can be evenly guided during the flow process. The design of the guide vanes 7 allows the fluid to flow along a specific path when passing through the plug-in 6.

[0047] Using the glyoxylic acid synthesis device of the present invention, solution A is injected into the left inlet of the inner tube 5 during operation. As it flows through the inner tube 5, it is ejected into the outer tube 4 through axially distributed distribution holes 9 (located on the inner tube 5). Solution B is then injected into the outer tube 4 through the feed port 3, where it reacts with the ejected solutions A and B within the outer tube 4. The spiral-shaped guide vane 7 within the insert 6 on the inner tube 5 promotes spiral motion during the flow of solution A, extending the fluid path and reducing dead zones, ensuring stable flow. The centrifugal effect generated by the spiral flow guide enhances the shearing effect between the fluids. Combined with the friction of the materials themselves and the driving force provided by the system pressure, it effectively prevents clogging and improves mixing efficiency. The contact between solutions A and B within the outer tube 4 is dynamic jet mixing, which, combined with the turbulent effect of the spiral flow, significantly improves the mixing uniformity of the two-phase reactants. The design of the distribution holes along the flow path enables segmented distribution, adapting to the gradient requirements of multi-stage reactions. The guide vane 7 increases the turbulence of the fluid, strengthens the contact area between phases, and thus enhances the mass transfer and heat transfer performance of the fluid. The fluid is fully mixed and reacted under the spiral guide, which reduces the residual unreacted materials and improves the utilization rate of raw materials. It is suitable for continuous production and further improves the overall energy efficiency.

[0048] The following are specific examples.

[0049] Example 1

[0050] A method for synthesizing glyoxylic acid comprises the following steps:

[0051] Step 1, preparing a nitric acid solution with a mass concentration of 40% as solution A-1;

[0052] Step 2: adding an initiator, sodium nitrite, to the glyoxal solution and stirring to dissolve it to obtain solution B-1; the molar ratio of nitric acid in solution A-1 to glyoxal in solution B-1 is 2:1; the molar ratio of the initiator, sodium nitrite, to glyoxal in solution B-1 is 0.2:1;

[0053] In step 3, solution A-1 was added to the inner tube 5 of the glyoxylic acid synthesis apparatus, and solution B-1 was added to the outer ring system. The inner tube 5 of the tubular microreactor, which allows for flow distribution, had a diameter of 12 mm, an outer tube 4 of 15 mm, and a gap of 13.8 mm between the outer rings. Distribution holes 9 were provided on the inner tube 5, each with a diameter of 1.2 mm and a spacing of 30 mm. There were four distribution holes distributed along the circumference. Solutions A-1 and B-1 reacted within the outer ring system at 65°C for 8 minutes. The mixture discharged from outlet 8 and was separated and analyzed using high-performance liquid chromatography to obtain the target product, glyoxylic acid, in a yield of 91.5%.

[0054] See also Figure 5 , Figure 5This is the HPLC chromatogram of Example 1. The peak at a retention time of 6-7 min is the peak of the by-product oxalic acid, the peak at a retention time of 8.5-9.5 min is the peak of the main product glyoxylic acid, and the peak at a retention time of 13-14 min is the peak of the by-product formic acid.

[0055] Compared with the yield of 89.2% in the literature (Wang J, Zhan W, Li Y, et al. Complete kinetic model and process reengineering of glyoxal oxidation by nitric acid in a capillary microreactor [J]. Reaction Chemistry & Engineering, 2024, 9 (11): 3016-3028.), the yield of glyoxylic acid prepared in the present invention is increased by 2.3%.

[0056] Example 2

[0057] A method for synthesizing glyoxylic acid comprises the following steps:

[0058] Step 1, preparing a nitric acid solution with a mass concentration of 30% as solution A-2;

[0059] Step 2: adding an initiator, sodium nitrite, to the glyoxal solution and stirring to dissolve it to obtain solution B-2; the molar ratio of nitric acid in solution A-2 to glyoxal in solution B-2 is 1:1; the molar ratio of the initiator, sodium nitrite, to glyoxal in solution B-2 is 0.3:1;

[0060] In step 3, solution A-2 was added to the inner tube 5 of the glyoxylic acid synthesis apparatus, and solution B-2 was added to the outer ring system. The inner tube of the tubular microreactor, which enables flow distribution, had an inner tube diameter of 0.2 mm, an outer tube 4 of 2 mm, and a gap of 1.8 mm between the outer rings. Distribution holes 9 were provided on the inner tube with a diameter of 0.6 mm and spaced 180 mm apart. There were three distribution holes distributed along the circumference. Solutions A-2 and B-2 reacted within the outer ring system at 75°C for 9 minutes. The mixture flowed out of outlet 8 and was detected and separated using high-performance liquid chromatography to obtain the target product, glyoxylic acid, in a yield of 87.5%.

[0061] See also Figure 6 , Figure 6 This is the HPLC chromatogram of Example 2. The peak at a retention time of 6-7 min is the peak of the by-product oxalic acid, the peak at a retention time of 8.5-9.5 min is the peak of the main product glyoxylic acid, and the peak at a retention time of 13-14 min is the peak of the by-product formic acid.

[0062] Compared with the yield of 81.6% in the literature (Zhan W, Wang J, He C, et al. Kinetics of glyoxal oxidation bynitric acid in acapillary microreactor [J]. Chemical Engineering Science, 2023, 276: 118813.), the yield of glyoxylic acid prepared in the present invention is increased by 5.9%.

[0063] Example 3

[0064] A method for synthesizing glyoxylic acid comprises the following steps:

[0065] Step 1, preparing a nitric acid solution with a mass concentration of 60% as solution A-3;

[0066] Step 2: adding an initiator, sodium nitrite, to the glyoxal solution and stirring to dissolve it to obtain solution B-3; the molar ratio of nitric acid in solution A-3 to glyoxal in solution B-3 is 4:1; the molar ratio of the initiator, sodium nitrite, to glyoxal in solution B-3 is 0.5:1;

[0067] In step 3, solution A-3 was added to the inner tube of a glyoxylic acid synthesis apparatus, and solution B-3 was added to the outer ring system. The inner tube microreactor, which enables flow distribution, had an inner tube diameter of 20 mm and an outer tube diameter of 28 mm, with an outer ring system gap of 8 mm. The inner tube was provided with two 1.8 mm diameter distribution holes spaced 250 mm apart, distributed around the circumference. Solutions A-3 and B-3 were reacted within the outer ring system at 45°C for 4 minutes. The mixture was discharged from the outlet and separated using high-performance liquid chromatography to obtain the target product, glyoxylic acid, in a yield of 88.7%.

[0068] See also Figure 7 , Figure 7 This is the HPLC chromatogram of Example 3. The peak at a retention time of 6-7 min is the peak of the by-product oxalic acid, the peak at a retention time of 8.5-9.5 min is the peak of the main product glyoxylic acid, and the peak at a retention time of 13-14 min is the peak of the by-product formic acid.

[0069] Compared with the yield of 84.00% in the literature (Li Guangyao, Cheng Zhengzai, Wang Handing, et al. Preparation and rapid analysis of glyoxylic acid by oxygen-nitric acid combined oxidation [J]. Journal of Henan University of Science&Technology, Natural Science, 2019, 40(2).), the yield of glyoxylic acid prepared in the present invention is increased by 4.7%.

[0070] Example 4

[0071] A method for synthesizing glyoxylic acid comprises the following steps:

[0072] Step 1, preparing a nitric acid solution with a mass concentration of 35% as solution A-3;

[0073] Step 2: adding an initiator, sodium nitrite, to the glyoxal solution and stirring to dissolve it to obtain solution B-3; the molar ratio of nitric acid in solution A-3 to glyoxal in solution B-3 is 2:1; the molar ratio of the initiator, sodium nitrite, to glyoxal in solution B-3 is 0, i.e., no initiator, sodium nitrite, is added;

[0074] In step 3, solution A-3 was added to the inner tube 5 of the glyoxylic acid synthesis apparatus, and solution B-3 was added to the outer ring system. The inner tube 5 of the tubular microreactor, which enables flow distribution, had a diameter of 10 mm, an outer tube 4 of 20 mm, and a gap of 10 mm between the outer rings. Six distribution holes 9 were provided on the inner tube, each with a diameter of 1 mm and spaced 200 mm apart. Solutions A-3 and B-3 reacted within the outer ring system at 68°C for 10 minutes. The mixture flowed out of outlet 8 and was separated and analyzed using high-performance liquid chromatography to obtain the target product, glyoxylic acid, in a yield of 81%.

[0075] See also Figure 8 , Figure 8 This is the HPLC chromatogram of Example 4. The peak at a retention time of 6-7 min is the peak of the by-product oxalic acid, the peak at a retention time of 8.5-9.5 min is the peak of the main product glyoxylic acid, and the peak at a retention time of 13-14 min is the peak of the by-product formic acid.

[0076] Compared with the yield of 60.2% in the literature (Wang Qihua, Wang Cunwen, Chen Sufang, et al. Study on the synthesis of glyoxylic acid by air catalytic oxidation of glyoxal [J]. Journal of Wuhan University of Technology, 2008, 30(4): 25-27.), the yield of glyoxylic acid prepared in the present invention is increased by 20.8%.

[0077] The yield and selectivity of the glyoxylic acid products prepared in Examples 1-4 are shown in Table 1:

[0078] Table 1 Yield and selectivity of Examples 1-4

[0079] Example Yield / % Selectivity / % Example 1 91.5％ 97.2％ Example 2 87.5％ 91.3％ Example 3 88.7％ 90％ Example 4 81％ 89％

[0080] As can be seen from Table 1, the yield of glyoxylic acid in the method for synthesizing glyoxylic acid of the present invention is not less than 80%, and the selectivity is not less than 85%.

[0081] The above description is merely a description of the preferred embodiment of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiment, and variations in the specific structure are permitted. Any variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0082] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A synthesis device for glyoxylic acid, characterized in that: The invention comprises a first joint (1), a second joint (2), an outer tube (4) and an inner tube (5); a feed port (3) is provided on the upper portion of the first joint (1), and a discharge port (8) is provided at one end of the second joint (2); an outer tube (4) is provided between the first joint (1) and the second joint (2); an inner tube (5) is provided inside the outer tube (4); one end of the inner tube (5) passes through the outer tube (4), while the other end does not pass through the outer tube (4); an entrance is provided at the front end of the inner tube (5) near the first joint (1), and a rear end of the inner tube (5) near the second joint (2) is sealed; a plurality of plug-ins (6) are sleeved on the outer wall of the inner tube (5); a guide plate (7) is provided on the plug-in (6); the guide plate (7) is provided in a spiral shape; and distribution holes (9) are provided on the outer wall of the inner tube (5) and between adjacent guide plates (7).

2. The synthesis device of glyoxylic acid according to claim 1, characterized in that The plug-in unit (6) is provided with a fixing ring (10) for fixing the guide plate (7).

3. The synthesis device of glyoxylic acid according to claim 2, characterized in that The number of the guide plates (7) is 2-12.

4. The synthesis device of glyoxylic acid according to claim 1 or 2, characterized in that The guide plate (7) is in a curved shape, and the bending angle is 30-120 degrees.

5. The synthesis device of glyoxylic acid according to claim 1, characterized in that The material distribution holes (9) are circular, and the apertures of the material distribution holes (9) are equal or the apertures of the material distribution holes (9) increase in a gradient along the axial direction of the inner tube 5.

6. The synthesis device of glyoxylic acid according to claim 1, characterized in that The diameter of the distribution holes 9 increases by 0.1-2 mm along the flow direction.

7. A method for synthesizing glyoxylic acid based on the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: A nitric acid solution is injected from the inlet, flows through the inner tube (5), and then is ejected into the outer tube (4) through the distribution hole (9). An initiator glyoxal solution is injected into the outer tube (4) from the feed port. The initiator glyoxal solution reacts with the nitric acid solution to generate glyoxylic acid.

8. The method for synthesizing glyoxylic acid according to claim 7, wherein: The mass concentration of the nitric acid solution is 30%-60%, and the initiator is sodium nitrite.

9. The method for synthesizing glyoxylic acid according to claim 8, wherein The molar ratio of nitric acid to glyoxal is 1-5:1, and the molar ratio of initiator to glyoxal is 0-0.5:

1.

10. The method for synthesizing glyoxylic acid according to claim 8, wherein The reaction temperature is 25-80°C and the reaction time is 5-10 minutes.

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