Device and method for refining benzaldehyde through photocatalysis

Abstract

The invention provides a device and a method for refining benzaldehyde through photocatalysis. The device comprises a main body tank, a transparent quartz tube, an inner light source arranged in the transparent quartz tube, and a partition plate arranged between the transparent quartz tube and the peripheral wall of the main body tank, and a plurality of through holes are formed in the partition plate. The transparent quartz tube is lower than the peripheral wall of the main body tank; the bottom wall of the main body tank is provided with a material inlet for inputting crude benzaldehyde and a material outlet for outputting the photocatalytic benzaldehyde. Through the arrangement, crude benzaldehyde enters the transparent quartz tube through the material inlet, flows upwards under the illumination of the LED with the wavelength of 350-380 nm, overflows outwards after reaching the top of the transparent quartz tube, penetrates through the partition plate and is continuously discharged through the discharge port, rapid decomposition of peroxide under photocatalysis is achieved, the quality and stability of the finished benzaldehyde are improved, and the quality of the finished benzaldehyde is improved. The rectified benzaldehyde has the advantages of low acid value, low color number, high content and no peculiar smell, meets the requirements of high-end benzaldehyde, and can be stored for a long time without deterioration.

Description

Technical Field

[0001] This invention relates to the field of benzaldehyde preparation technology, and in particular to an apparatus and method for photocatalytic purification of benzaldehyde. Background Technology

[0002] Benzaldehyde synthesized via oxidation contains trace amounts of peroxides. These peroxides cannot be completely separated during distillation purification and are easily carried over into the finished product. During subsequent storage, the peroxides slowly decompose to generate benzoic acid, peroxide rearrangement byproducts, and benzaldehyde condensation dimerization byproducts such as benzoin. This results in some batches of benzaldehyde exhibiting a darker color, increased acid value, more diverse impurities, and decreased content, significantly impacting product stability and limiting the high-end use of chlorine-free benzaldehyde. Furthermore, the byproducts from peroxide decomposition and rearrangement further inhibit the application of the produced benzaldehyde in food-grade benzaldehyde.

[0003] In existing technologies, peroxides and organic acids are removed by alkaline washing using composite packed columns, followed by distillation to obtain food-grade benzaldehyde. Alternatively, active metals are used to catalyze the decomposition of peroxides. However, composite packed columns require regular replacement and regeneration, and the active metals are also continuously consumed and regenerated, generating organic waste and scrap, which increases costs and environmental pressure.

[0004] In view of this, it is necessary to design a highly efficient, clean, waste-free, and pollution-free photocatalytic purification device and method for benzaldehyde to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and method for photocatalytic purification of benzaldehyde. This apparatus utilizes LED light in a specific wavelength band for directional catalytic oxidation to rapidly decompose and rearrange peroxides in benzaldehyde. After the peroxides are decomposed, the crude product has a stable composition and structure, which is then purified through a multi-stage continuous distillation column to obtain industrial-grade and food-grade benzaldehyde, respectively. The entire process generates no organic wastewater or waste packing material, making it environmentally friendly, and the entire process is completely continuous.

[0006] To achieve the above-mentioned objectives, this invention provides a photocatalytic purification apparatus for benzaldehyde. The apparatus includes a main tank, a transparent quartz tube protruding upwards from the bottom wall of the main tank, an internal light source disposed within the transparent quartz tube, and a partition disposed between the transparent quartz tube and the peripheral wall of the main tank. The partition has several through holes. The height of the transparent quartz tube is lower than the height of the peripheral wall of the main tank. The bottom wall of the main tank has a material inlet for inputting crude benzaldehyde and an outlet for outputting photocatalyzed benzaldehyde. The material inlet is located directly below the transparent quartz tube, and the discharge outlet is located between the transparent quartz tube and the peripheral wall of the main tank. The photocatalytic purification apparatus for benzaldehyde also includes a power unit for feeding crude benzaldehyde into the main tank. Crude benzaldehyde enters the transparent quartz tube through the material inlet and flows upward. After reaching the top of the transparent quartz tube, it overflows to the outside, passes through the partition, and is continuously discharged through the outlet, completing the peroxide decomposition process under photocatalysis.

[0007] Furthermore, the internal light source is an LED light source with a wavelength of 350-380nm.

[0008] Furthermore, the distance between the transparent quartz tube and the internal light source is 300-400mm.

[0009] Furthermore, the distance between the transparent quartz tube and the peripheral wall of the main tank is 600-700mm.

[0010] Furthermore, the height difference between the transparent quartz tube and the peripheral wall of the main tank is 100-200mm.

[0011] The present invention also provides a method for photocatalytic purification of benzaldehyde, wherein the method uses the photocatalytic purification apparatus for benzaldehyde described in the foregoing technical solution to perform photocatalytic treatment on the crude benzaldehyde output from the primary distillation column to remove the peroxides therein; Specifically, crude benzaldehyde from the primary distillation column is continuously fed into a transparent quartz tube. Under LED illumination with a wavelength of 350-380nm, the crude benzaldehyde flows upward and overflows to the outside after reaching the top of the transparent quartz tube. After passing through the partition, it is continuously discharged through the outlet, thus completing the peroxide decomposition process under photocatalysis.

[0012] Furthermore, the light intensity is 0.5-1 kW / h.

[0013] Furthermore, the crude benzaldehyde input rate is 0.5-1 ton / hour.

[0014] Furthermore, the temperature inside the transparent quartz tube is 50-60℃.

[0015] The beneficial effects of this invention are: 1. This application provides an apparatus for photocatalytic purification of benzaldehyde, the apparatus comprising a main tank, a transparent quartz tube protruding upward from the bottom wall of the main tank, an internal light source disposed within the transparent quartz tube, and a partition disposed between the transparent quartz tube and the peripheral wall of the main tank; the partition is provided with a plurality of through holes; the height of the transparent quartz tube is lower than the height of the peripheral wall of the main tank; the bottom wall of the main tank is provided with a material inlet for inputting crude benzaldehyde and an outlet for outputting photocatalytically purified benzaldehyde; the material inlet is located directly below the transparent quartz tube, and the outlet is located between the transparent quartz tube and the peripheral wall of the main tank; the apparatus for photocatalytic purification of benzaldehyde further includes a power component for inputting crude benzaldehyde into the main tank. With this setup, crude benzaldehyde enters the transparent quartz tube through the material inlet. Under LED light with a wavelength of 350-380nm, the crude benzaldehyde flows upwards, overflows to the outside after reaching the top of the transparent quartz tube, passes through the partition, and is continuously discharged through the outlet, completing the photocatalytic photo-oxidation decomposition process. This improves the quality of benzaldehyde, resulting in distilled benzaldehyde with low acid value, low color number, high content, no odor, meeting the requirements for food-grade benzaldehyde. It is also easy to store, has stable quality, and can be stored for a long time without deterioration.

[0016] 2. In this application, the distance between the transparent quartz tube and the internal light source is 300-400mm, and the distance between the transparent quartz tube and the peripheral wall of the main tank is 600-700mm. This arrangement ensures that the area closer to the internal light source receives high light intensity, allowing most of the peroxides to decompose rapidly. The material outside the transparent quartz tube experiences greater light intensity attenuation due to its greater distance from the LED light source, while the larger space between the transparent quartz tube and the main tank allows for a longer residence time, ensuring that any incompletely decomposed peroxides react completely.

[0017] 3. This application uses light of a specific wavelength to decompose peroxides, without consuming alkali or filler, and the entire process does not generate organic wastewater or waste filler, which is beneficial to environmental protection.

[0018] 4. This application provides a porous baffle between the transparent quartz tube and the main tank; the through holes on the porous baffle can physically force the material to flow laterally, promote back mixing, and avoid uneven light exposure of the material, thereby prolonging the residence time of the material in the entire reactor.

[0019] 5. In this application, crude benzaldehyde output from the primary distillation column is continuously fed into a transparent quartz tube from the bottom. The material enters the transparent quartz tube from bottom to top, and is catalyzed by a specific wavelength LED light source in the inner area with higher light intensity, activating the peroxide bonds. This anti-gravity setting ensures that the peroxides are fully irradiated, efficiently removing them. Simultaneously, by controlling the input rate of the crude benzaldehyde, the residence time of benzaldehyde under light is controlled, ensuring that the peroxides (peroxybenzoic acid) in the benzaldehyde are fully decomposed, followed by distillation to separate benzoic acid and other impurities. The resulting benzaldehyde has a high content, is stable, does not change color, and its acid value does not increase after prolonged sealed storage. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the apparatus for photocatalytic purification of benzaldehyde according to the present invention.

[0021] Figure 2 This is a schematic diagram illustrating the application of the photocatalytic purification apparatus for benzaldehyde according to the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0024] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0025] Please see Figures 1 to 2 As shown, an apparatus 100 for photocatalytic purification of benzaldehyde includes a main tank 10, a transparent quartz tube 20 protruding upward from the bottom wall of the main tank 10, an internal light source 30 disposed within the transparent quartz tube 20, and a partition 40 disposed between the transparent quartz tube 20 and the peripheral wall of the main tank 10. The partition 40 has several through holes. The height of the transparent quartz tube 20 is lower than the height of the peripheral wall of the main tank 10. The bottom wall of the main tank 10 has a material inlet 11 for inputting crude benzaldehyde and an outlet 12 for outputting photocatalyzed benzaldehyde. The material inlet 11 is located directly below the transparent quartz tube 20, and the outlet is located between the transparent quartz tube 20 and the peripheral wall of the main tank 10.

[0026] The internal light source 30 is an LED light source with a wavelength of 350-380nm.

[0027] The height difference between the transparent quartz tube 20 and the peripheral wall of the main tank 10 is 100-200mm, the distance between the transparent quartz tube 20 and the internal light source 30 is 300-400mm, and the distance between the transparent quartz tube 20 and the peripheral wall of the main tank 10 is 600-700mm. This arrangement ensures that the area closer to the internal light source receives high light intensity, allowing most of the peroxides to decompose rapidly. The material outside the transparent quartz tube 20 experiences greater light intensity attenuation due to its greater distance from the LED light source. However, the larger space between the transparent quartz tube 20 and the main tank 10 allows for a longer residence time of the material, ensuring that any incompletely decomposed peroxides react completely.

[0028] The photocatalytic benzaldehyde refining device also includes a power unit for feeding crude benzaldehyde into the main tank 10. As such, crude benzaldehyde enters the transparent quartz tube 20 through the material inlet 11 and flows upwards. After reaching the top of the transparent quartz tube 20, it overflows outwards, passes through the through-holes in the partition 40, and reaches the bottom of the main tank 10. It is then continuously discharged through the outlet 12, completing the photocatalytic photo-oxidation decomposition process. The approximate flow direction of benzaldehyde is as follows: Figure 1 As indicated by the middle arrow.

[0029] This application also provides a method for photocatalytic purification of benzaldehyde, wherein the crude benzaldehyde output from the primary distillation column is photocatalytically treated using the aforementioned photocatalytic purification apparatus to remove peroxides and residual organic acids therein. Specifically, the aforementioned photocatalytic benzaldehyde refining device is installed between the primary distillation column and the rectification column of the oxidative benzaldehyde production unit. The crude benzaldehyde output from the primary distillation column is continuously fed into the transparent quartz tube 20 through the material inlet 11. Under LED light with a wavelength of 350-380nm, the crude benzaldehyde flows upward and overflows to the outside after reaching the top of the transparent quartz tube 20. It passes through the through holes on the partition 40 and reaches the bottom of the main tank 10. It is then continuously discharged through the discharge port 12. The benzaldehyde completes the photocatalytic photo-oxidation decomposition process and then enters the rectification column for further rectification and purification, thus realizing the continuous operation of the photocatalytic benzaldehyde refining device.

[0030] The light intensity is 0.5-1 kilowatt-hour.

[0031] The crude benzaldehyde input rate is 0.5-1 ton / hour.

[0032] The temperature inside the transparent quartz tube 20 is 50-60℃.

[0033] This invention utilizes LED light-guided catalytic oxidation in a specific wavelength band to rapidly decompose and rearrange peroxides in benzaldehyde, thereby improving the quality of benzaldehyde. This results in benzaldehyde after distillation having a low acid value, low color number, high content, no odor, meeting the requirements for food-grade benzaldehyde, and being easy to store with stable quality.

[0034] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0035] Example 1 This embodiment provides a photocatalytic method for purifying benzaldehyde, using, for example... Figure 1 The apparatus shown for the photocatalytic purification of benzaldehyde includes the following process: An LED light source with a wavelength of 350nm is used as the internal light source; the input rate of crude benzaldehyde is controlled at 1 ton / hour, the light intensity is 1 kilowatt / hour, the temperature inside the transparent quartz tube 20 is 50℃, and the residence time of benzaldehyde in the main tank 10 is 5 hours.

[0036] Comparative Example 1 Comparative Example 1 provides a method for photocatalytic purification of benzaldehyde, the main difference from Example 1 being that the photocatalytic purification device used for benzaldehyde purification does not include a transparent quartz tube. Other aspects are largely the same as in Example 1 and will not be repeated here.

[0037] Comparative Example 2 Comparative Example 2 provides a method for photocatalytic purification of benzaldehyde, the main difference from Example 1 being that the photocatalytic purification device used for benzaldehyde purification does not include a separator. Other aspects are largely the same as in Example 1 and will not be repeated here.

[0038] Comparative Example 3 Comparative Example 3 provides a method for treating benzaldehyde by oxidation. The main difference from Example 1 is that no photocatalytic purification device for benzaldehyde is installed between the primary distillation column and the rectification column; that is, the crude benzaldehyde product from the primary distillation column in Comparative Example 1 is directly fed into the rectification column for distillation treatment.

[0039] Examples 2-3 and Comparative Examples 4-5 The main difference between Examples 2-3 and Comparative Examples 4-5 and Example 1 is that the wavelength of the internal light source was changed, as shown in Table 1. Everything else is largely the same as Example 1 and will not be repeated here.

[0040] Examples 4-5 and Comparative Examples 6-7 The main differences between Examples 4-5 and Comparative Examples 6-7 and Example 1 are: the input rate of crude benzaldehyde, the light intensity, and the temperature inside the transparent quartz tube were changed, as shown in Table 1. Other aspects are largely the same as in Example 1 and will not be repeated here.

[0041] Table 1 Comparison of process parameters in Examples 1-5 and Comparative Examples 4-7 The distillation products obtained in the examples and comparative examples were stored for 30 days and then sampled and tested. The test items included acid value, color number, peroxide value, and benzaldehyde content. The results are shown in Table 2.

[0042] Table 2. Test results of products from Example 1 and Comparative Example 1 Table 2 shows that, in the comparison of 30 days before and after Examples 1-5, the preferred light wavelength, preferred light power, and preferred residence time resulted in the complete decomposition of peroxides in the initial distillation benzaldehyde into other stable impurities. After multi-stage distillation, a benzaldehyde product with low acid value, low color number, no peroxide value, and high content was obtained. As shown in Comparative Example 1, when the light wavelength is too short, the LED light energy is high but the penetration ability is too weak, failing to fully irradiate all the material to decompose the peroxides. Similarly, in Comparative Example 2, when the light wavelength is too long, the LED light energy is low, reducing the efficiency of catalyzing the decomposition of peroxides. Both excessively long and short wavelengths lead to incomplete decomposition of peroxides in the distillation product benzaldehyde. After 30 days of storage, the acid value and color number of the finished benzaldehyde product increased significantly.

[0043] While increasing the feed rate of the photoluminescence reactor and simultaneously increasing the light irradiation power may seem to keep the light intensity per unit of material per unit time constant, the shorter residence time of the material in the reactor prevents complete decomposition of the peroxides. Maintaining a constant material flow rate while further increasing the light irradiation intensity can lead to complete decomposition of the peroxides, but this increases energy consumption and accelerates the degradation of the LED light source at high power.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An apparatus for photocatalytic purification of benzaldehyde, characterized in that, The device includes a main tank, a transparent quartz tube protruding upward from the bottom wall of the main tank, an internal light source disposed inside the transparent quartz tube, and a partition disposed between the transparent quartz tube and the peripheral wall of the main tank; the partition is provided with a plurality of through holes; the height of the transparent quartz tube is lower than the height of the peripheral wall of the main tank; the bottom wall of the main tank is provided with a material inlet for crude benzaldehyde input and an outlet for photocatalytic benzaldehyde output; The material inlet is located directly below the transparent quartz tube, and the discharge outlet is located between the transparent quartz tube and the peripheral wall of the main tank. The photocatalytic purification apparatus for benzaldehyde also includes a power unit for feeding crude benzaldehyde into the main tank. Crude benzaldehyde enters the transparent quartz tube through the material inlet and flows upward. After reaching the top of the transparent quartz tube, it overflows to the outside, passes through the partition, and is continuously discharged through the outlet, completing the peroxide decomposition process under photocatalysis.

2. The apparatus for photocatalytic purification of benzaldehyde according to claim 1, characterized in that, The internal light source is an LED light source with a wavelength of 350-380nm.

3. The apparatus for photocatalytic purification of benzaldehyde according to claim 1, characterized in that, The distance between the transparent quartz tube and the internal light source is 300-400mm.

4. The apparatus for photocatalytic purification of benzaldehyde according to claim 1, characterized in that, The distance between the transparent quartz tube and the peripheral wall of the main tank is 600-700mm.

5. The apparatus for photocatalytic purification of benzaldehyde according to claim 1, characterized in that, The height difference between the transparent quartz tube and the peripheral wall of the main tank is 100-200mm.

6. A method for photocatalytic purification of benzaldehyde, characterized in that, The method uses the photocatalytic purification apparatus for benzaldehyde as described in any one of claims 1-5 to perform photocatalytic treatment on the crude benzaldehyde output from the primary distillation column to remove peroxides therein; Specifically, crude benzaldehyde from the primary distillation column is continuously fed into a transparent quartz tube. Under LED illumination with a wavelength of 350-380nm, the crude benzaldehyde flows upward and overflows to the outside after reaching the top of the transparent quartz tube. After passing through the partition, it is continuously discharged through the outlet, thus completing the peroxide decomposition process under photocatalysis.

7. The method for photocatalytic purification of benzaldehyde according to claim 6, characterized in that, The light intensity is 0.5-1 kilowatts per hour.

8. The method for photocatalytic purification of benzaldehyde according to claim 6, characterized in that, The crude benzaldehyde input rate is 0.5-1 ton / hour.

9. The method for photocatalytic purification of benzaldehyde according to claim 6, characterized in that, The temperature inside the transparent quartz tube is 50-60℃.

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