A method for preparing organic acids by catalytic selective oxidation of aromatic aldehydes
By activating molecular oxygen at room temperature using a metal-nitrogen coordination complex catalyst, the high temperature and high energy consumption problems of existing technologies are solved, realizing a highly efficient, low-cost, and environmentally friendly catalytic process for the selective oxidation of aromatic aldehydes to organic acids.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-12-03
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies using multiphase non-precious metal catalysts require high reaction temperatures and large catalyst dosages, resulting in high energy consumption and high production costs. Furthermore, molecular oxygen cannot directly oxidize aromatic aldehydes; it must be activated into an excited state to achieve selective oxidation.
A metal-nitrogen coordinated complex catalyst is used to construct a catalyst that activates molecular oxygen by forming an electron-rich surface and introducing fluorine-doped carbon, thereby reducing the activation energy and temperature of the aromatic aldehyde oxidation reaction. Air or oxygen is used as the oxidant to catalyze the oxidation of aromatic aldehydes to produce organic acids at room temperature.
It achieves efficient catalytic oxidation of aromatic aldehydes under mild conditions, reduces energy consumption, minimizes byproduct formation, and increases the yield of target products, meeting the requirements of green chemistry and possessing good economic and environmental benefits.
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Abstract
Description
Technical Field
[0001] This application relates to a method for the selective oxidation of aromatic aldehydes to prepare organic acids, which belongs to the field of chemical engineering. Background Technology
[0002] The oxidation of aldehydes plays a crucial role in organic and industrial chemistry. Its core objective is to convert aldehydes into products of higher oxidation states (such as carboxylic acids, esters, or carbon dioxide), a process that forms the basis for the production of chemicals, materials, pharmaceuticals, and fuels. However, the use of heterogeneous non-precious metal catalysts typically requires high reaction temperatures. For example, in the oxidation of furfural, the use of non-precious metal catalysts (such as cobalt or manganese oxides) requires a large amount of catalyst, with the metal-to-reactant molar ratio reaching up to 6:1, and the reaction temperature is usually between 80 and 130 °C (see: Journal of Energy Chemistry, 2021, 54: 528-554; ChemSusChem, 2017, 10: 654-658; ChemSusChem, 2018, 11: 3323-3334). To reduce catalyst usage, reaction temperature, energy consumption, and ultimately production costs, thereby promoting the widespread application of aldehyde oxidation to organic acid technology, designing highly active non-precious metal catalysts capable of efficiently catalyzing aromatic aldehyde oxidation reactions under mild or even room temperature conditions has become a critical issue. Enhancing the oxidizing power of the aromatic aldehyde oxidation system is key to lowering the activation energy and temperature. When molecular oxygen is used as the oxidant, it cannot directly oxidize aromatic aldehydes due to the energy level mismatch between ground-state oxygen molecules and aromatic aldehyde compounds. Ground-state oxygen molecules need to be activated to an excited state to form reactive oxygen species, which then play a selective oxidation role (Chemical Reviews, 2017, 117: 11302-11336). The participation of highly oxidizing reactive oxygen species in aromatic aldehyde oxidation reactions may lower the activation energy and temperature of the reaction. Summary of the Invention
[0003] In the process of preparing the catalyst, this invention uses a metal-nitrogen coordinated complex to ensure high metal dispersion. Nitrogen-containing compounds are added to form an electron-rich surface during pyrolysis, thereby constructing a catalyst that activates molecular oxygen. Fluorine-doped carbon is introduced to change the electron distribution of the catalyst. The excellent performance of the catalyst enables molecular oxygen to be activated into highly reactive oxygen species, which can reduce the activation energy and temperature of the aromatic aldehyde oxidation reaction. Furthermore, the amount of metal used is small and the utilization rate is high.
[0004] This invention provides a method for catalytic oxidation of aromatic aldehydes to prepare organic acids at room temperature. The method uses a transition metal heterogeneous catalyst, with air or oxygen as the oxidant in an aqueous phase, to catalyze the efficient and selective oxidation of aromatic aldehydes in an alkaline environment to generate organic acids.
[0005] In this method, the prepared catalyst's active metal component is a uniformly dispersed nanostructure, which helps improve the catalyst's stability and catalytic performance. Simultaneously, the catalyst surface is rich in electrons, which promotes the generation of highly oxidizing reactive oxygen species, thereby effectively driving the catalytic oxidation reaction of aromatic aldehydes.
[0006] According to one aspect of this application, a method for the selective oxidation of aromatic aldehydes to prepare organic acids is provided, characterized in that...
[0007] Includes the following steps:
[0008] In a reactor at room temperature under an oxygen-containing atmosphere, aromatic aldehydes, catalysts, alkaline additives, and water are mixed to obtain a mixture, which is then reacted and acidified to obtain organic acids.
[0009] The aromatic aldehyde is selected from at least one of benzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-nitrobenzaldehyde, 3,4-dimethoxybenzaldehyde, 3,4,5-trimethoxybenzaldehyde, p-phenylenedialdehyde, iso-phenylenedialdehyde, m-methylbenzaldehyde, 2,5-dimethylbenzaldehyde, and 3,4-dimethylbenzaldehyde.
[0010] The organic acid is selected from at least one of benzoic acid, 3,4,5-trimethoxybenzoic acid, p-methylbenzoic acid, p-nitrobenzoic acid, 3,4-dimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, terephthalic acid, isophthalic acid, m-methylbenzoic acid, 2,5-dimethylbenzoic acid, and 3,4-dimethylbenzoic acid.
[0011] The catalyst is obtained through the following steps:
[0012] The metal-nitrogen complex was mixed with a nitrogen-containing compound, ground, pyrolyzed under an inactive gas atmosphere, mixed with a fluorine-containing monomer, calcined, centrifuged, and dried to obtain the catalyst.
[0013] The alkaline additive is selected from at least one of NaOH, NaHCO3, Na2CO3, KOH, KHCO3, and K2CO3;
[0014] The molar ratio of the alkali additive to the aromatic aldehyde is 1:1 to 10:1;
[0015] The concentration of aromatic aldehydes in the mixture is 0.1–10 mol / L;
[0016] The reaction temperature is 25–60°C;
[0017] The reaction time is 0.5–48 h;
[0018] The reaction was carried out at atmospheric pressure to 2 MPa.
[0019] The acidification is achieved by adding a 1-3 mol / L sulfuric acid aqueous solution.
[0020] The metal-nitrogen complex is selected from at least one of tetraphenylporphyrin iron, tetracarboxyphenylporphyrin iron, tetraaminophenylporphyrin iron, phthalocyanine iron, Fe(Phen)2 (Phen = o-phenanthroline), phenylporphyrin cobalt, tetracarboxyphenylporphyrin cobalt, tetraaminophenylporphyrin cobalt, phthalocyanine cobalt, Co(Phen)2, tetraphenylporphyrin manganese, tetracarboxyphenylporphyrin manganese, tetraaminophenylporphyrin manganese, phthalocyanine manganese, and Mn(Phen)2;
[0021] The nitrogen-containing compound is selected from at least one of carbon nitride, melamine, cyanuric acid, urea, dicyandiamide, polypyrrole, and o-phenanthroline;
[0022] The inactive gas atmosphere is selected from nitrogen atmosphere and / or inert gas atmosphere;
[0023] The fluorinated monomer is selected from at least one of 4-fluorophenol, 3-fluorophenol, 3-(trifluoromethoxy)phenol, and 4-(trifluoromethyl)phenol.
[0024] The mass ratio of the metal-nitrogen complex to the nitrogen-containing compound is 1:2 to 1:20.
[0025] The pyrolysis temperature is 300–900℃;
[0026] The pyrolysis time is 1 to 6 hours;
[0027] The calcination temperature is 130–160°C.
[0028] The roasting time is 5 to 6 hours.
[0029] After pyrolysis, it is etched with acid;
[0030] The acid etching is performed using a 0.5–3 mol / L sulfuric acid aqueous solution at a temperature of 25–90 °C for 12–24 hours.
[0031] The mass content of the metal element in the catalyst is 2-25 wt%.
[0032] The metallic element is selected from at least one of iron, cobalt, and manganese.
[0033] Typical synthesis method A: Tetraphenylporphyrin cobalt and carbon nitride are mixed in a mass ratio of 1:10, ground in an agate mortar for 1 hour, transferred to an inert atmosphere of N2, heated at a heating rate of 10 °C / min, held at 800 °C for 2 hours, 4-fluorophenol is added, and the reaction is carried out in a reactor at 130 °C for 5 hours. After centrifugation and drying, the Co@F-CN catalyst is obtained.
[0034] Typical synthesis method B: Cobalt phthalocyanine and dicyandiamine are mixed at a mass ratio of 1:15, ground in an agate mortar for 1 hour, transferred to an inert atmosphere of N2, heated at a heating rate of 10℃ / min, held at 800℃ for 2 hours, 3-fluorophenol is added, and the reaction is carried out in a reactor at 130℃ for 5 hours. After centrifugation and drying, Co@F-DCD catalyst is obtained.
[0035] Typical synthesis method C: Co(Phen)2 and carbon nitride are mixed in a mass ratio of 1:10 and ground in an agate mortar for 1 h. The mixture is then transferred to an inert atmosphere N2 and heated at a heating rate of 10 °C / min for 2 h at 800 °C. The resulting black solid is transferred to a 2 mol / L sulfuric acid aqueous solution and stirred at 80 °C for 12 h. The sulfuric acid is washed away with deionized water and the mixture is dried under vacuum. 3(trifluoromethoxy)phenol is added and reacted in a reactor at 130 °C for 5 h. The mixture is then centrifuged and dried to obtain the Co@F-CN-H catalyst.
[0036] Typical synthesis method D: Fe(Phen)2, Co(Phen)2 and melamine are mixed in a mass ratio of 1:1:30 and ground in an agate mortar for 1 h. The mixture is then transferred to an inert atmosphere N2 and heated at a heating rate of 10 °C / min. The temperature is maintained at 800 °C for 2 h. 4-(trifluoromethyl)phenol is added and reacted in a reactor at 130 °C for 5 h. The mixture is then centrifuged and dried to obtain the FeCo@F-CN catalyst.
[0037] Typical synthesis method E: Cobalt phthalocyanine, manganese phthalocyanine and cyanuric acid are mixed in a mass ratio of 1:1:30, ground in an agate mortar for 1 h, transferred to an inert atmosphere N2, heated at a heating rate of 10 °C / min, held at 800 °C for 2 h, 4-(trifluoromethyl)phenol is added and reacted in a reactor at 130 °C for 5 h, centrifuged and dried to obtain CoMn@F-TCA catalyst.
[0038] Compared with existing reports, the present invention has the following advantages:
[0039] (1) Transition metal catalysts can efficiently catalyze the conversion of aromatic aldehydes into aromatic acids in the oxidation reaction of aromatic aldehydes. They have good catalytic activity and high selectivity, which can effectively reduce the generation of by-products and improve the yield of target products.
[0040] (2) Unlike traditional noble metal catalysts or reactions under high temperature and high pressure conditions, the catalyst of the present invention can be catalyzed under mild reaction conditions (such as room temperature or slightly higher temperature), which significantly reduces energy consumption and reduces the requirements for equipment and reaction conditions, and has better operational convenience.
[0041] (3) By using mild reaction conditions and a low amount of catalyst, this method reduces energy consumption in the reaction process, thereby reducing production costs. It conforms to the concept of green chemistry and has good economic and environmental benefits.
[0042] (4) The transition metal catalyst used in this invention is a non-precious metal catalyst (such as cobalt, manganese, etc.). Compared with precious metal catalysts, it is cheaper and still has excellent catalytic performance, which helps to reduce the overall production cost and has strong industrial application potential.
[0043] (5) By rationally designing the structure and performance of the catalyst, the catalyst can still maintain good catalytic activity and stability after multiple uses and has high reusability. This not only saves the consumption of catalyst, but also reduces the burden on the environment.
[0044] (6) This method uses air or oxygen as an oxidant and water as a solvent, which meets the requirements of green chemistry, reduces the use of harmful solvents or chemical reagents, avoids environmental pollution, and conforms to the concept of sustainable development. Detailed Implementation
[0045] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0046] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0047] Example 1:
[0048] Co@F-CN catalyst, 0.5 mmol benzaldehyde, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:benzaldehyde ratio was 0.15:1 (mol:mol). The temperature was raised to 25 °C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 12 hours, maintaining a constant pressure throughout the process. The reaction solution was acidified to obtain benzoic acid, which was analyzed by HPLC. The results are shown in Table 1.
[0049] Example 2:
[0050] Co@F-DCD catalyst, 0.5 mmol benzaldehyde, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:benzaldehyde ratio was 0.15:1 (mol:mol). The temperature was programmed to reach 25 °C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 12 hours, maintaining a constant pressure throughout the process. The reaction solution was acidified to obtain benzoic acid, which was analyzed by HPLC. The results are shown in Table 1.
[0051] Example 3:
[0052] Co@F-CN-H catalyst, 0.5 mmol benzaldehyde, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:benzaldehyde ratio was 0.15:1 (mol:mol). The temperature was programmed to reach 25 °C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 12 hours, maintaining a constant pressure throughout the process. The reaction solution was acidified to obtain benzoic acid, which was analyzed by HPLC. The results are shown in Table 1.
[0053] Example 4:
[0054] Co@F-CN catalyst, 0.5 mmol furfural, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:furfural ratio was 0.15:1 (mol:mol). The temperature was programmed to reach 25 °C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 10 hours, maintaining a constant pressure throughout the process. After acidification, furoic acid was obtained and analyzed by HPLC. The results are shown in Table 1.
[0055] Example 5:
[0056] Co@F-DCD catalyst, 0.5 mmol furfural, 2.0 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:furfural ratio was 0.25:1 (mol:mol). The temperature was programmed to reach 25°C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 10 hours, maintaining a constant pressure throughout the process. After acidification, furoic acid was obtained and analyzed by HPLC. The results are shown in Table 1.
[0057] Example 6:
[0058] Co@F-CN-H catalyst, 0.5 mmol furfural, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:furfural ratio was 0.15:1 (mol:mol). The temperature was programmed to reach 25°C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 10 hours, maintaining a constant pressure throughout the process. After acidification, furoic acid was obtained and analyzed by HPLC. The results are shown in Table 1.
[0059] Example 7:
[0060] Co@F-CN catalyst, 0.5 mmol of 2,5-dimethylbenzaldehyde, 1.25 mmol of NaOH, and 5 mL of deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE). The metal to 2,5-dimethylbenzaldehyde ratio was 0.15:1 (mol:mol). The temperature was raised to 25°C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 6 hours while maintaining a constant pressure. After acidification, the reaction solution yielded 2,5-dimethylbenzoic acid, which was analyzed by HPLC. The results are shown in Table 1.
[0061] Example 8:
[0062] Co@F-DCD catalyst, 2,5-dimethylbenzaldehyde, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE). The metal to 2,5-dimethylbenzaldehyde ratio was 0.15:1 (mol:mol). The temperature was raised to 25 °C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 6 hours while maintaining a constant pressure. After acidification, the reaction solution yielded 2,5-dimethylbenzoic acid, which was analyzed by HPLC. The results are shown in Table 1.
[0063] Example 9:
[0064] Co@F-CN-H catalyst, 2,5-dimethylbenzaldehyde, 2.0 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE). The metal to 2,5-dimethylbenzaldehyde ratio was 0.25:1 (mol:mol). The temperature was raised to 25°C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 6 hours while maintaining a constant pressure. After acidification, the reaction solution yielded 2,5-dimethylbenzoic acid, which was analyzed by HPLC. The results are shown in Table 1.
[0065] Example 10:
[0066] FeCo@F-CN catalyst, 0.5 mmol furfural, 2.0 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:furfural ratio was 0.2:1 (mol:mol). The temperature was programmed to reach 25 °C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 18 hours, maintaining a constant pressure throughout the process. After acidification, furoic acid was obtained and analyzed by HPLC. The results are shown in Table 1.
[0067] Example 11:
[0068] CoMn@F-TCA catalyst, 0.5 mmol furfural, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), with a metal:furfural ratio of 0.15:1 (mol:mol). The temperature was programmed to reach 25 °C using an automatic temperature controller, and 0.5 MPa of oxygen was added. The reaction was carried out for 18 hours, maintaining a constant pressure throughout the process. After acidification, furoic acid was obtained and analyzed by HPLC. The results are shown in Table 1.
[0069] Example 12:
[0070] FeCo@F-CN catalyst, 0.5 mmol furfural, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:furfural ratio was 0.15:1 (mol:mol). The temperature was programmed to reach 25 °C using an automatic temperature controller, and 0.5 MPa air was added. The reaction was carried out for 24 hours, maintaining a constant pressure throughout the process. After acidification, furoic acid was obtained and analyzed by HPLC. The results are shown in Table 1.
[0071] Example 13:
[0072] CoMn@F-TCA catalyst, 0.5 mmol furfural, 1.25 mmol NaOH, and 5 mL deionized water were added to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), wherein the metal:furfural ratio was 0.15:1 (mol:mol). The temperature was programmed to reach 25°C using an automatic temperature controller, and 0.5 MPa air was added. The reaction was carried out for 24 hours, maintaining a constant pressure throughout the process. After acidification, furoic acid was obtained and analyzed by HPLC. The results are shown in Table 1.
[0073] Table 1 Results of aromatic aldehyde catalytic oxidation on different catalysts
[0074]
[0075]
[0076] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for the selective oxidation of aromatic aldehydes to prepare organic acids, characterized in that, Includes the following steps: In a reactor at room temperature under an oxygen-containing atmosphere, aromatic aldehydes, catalysts, alkaline additives, and water are mixed to obtain a mixture, which is then reacted and acidified to obtain organic acids. The aromatic aldehyde is selected from at least one of benzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-nitrobenzaldehyde, 3,4-dimethoxybenzaldehyde, 3,4,5-trimethoxybenzaldehyde, p-phenylenedialdehyde, iso-phenylenedialdehyde, m-methylbenzaldehyde, 2,5-dimethylbenzaldehyde, and 3,4-dimethylbenzaldehyde. The organic acid is selected from at least one of benzoic acid, 3,4,5-trimethoxybenzoic acid, p-methylbenzoic acid, p-nitrobenzoic acid, 3,4-dimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, terephthalic acid, isophthalic acid, m-methylbenzoic acid, 2,5-dimethylbenzoic acid, and 3,4-dimethylbenzoic acid. The catalyst is obtained through the following steps: The metal-nitrogen complex was mixed with a nitrogen-containing compound, ground, pyrolyzed under an inactive gas atmosphere, mixed with a fluorine-containing monomer, calcined, centrifuged, and dried to obtain the catalyst.
2. The method according to claim 1, characterized in that, The alkaline additive is selected from at least one of NaOH, NaHCO3, Na2CO3, KOH, KHCO3, and K2CO3; The molar ratio of the alkali additive to the aromatic aldehyde is 1:1 to 10:1; The concentration of aromatic aldehydes in the mixture is 0.1–10 mol / L; The reaction temperature is 25–60°C; The reaction time is 0.5–48 h; The reaction was carried out at atmospheric pressure to 2 MPa. The acidification is achieved by adding a 1-3 mol / L sulfuric acid aqueous solution.
3. The method according to claim 1, characterized in that, The metal-nitrogen complex is selected from at least one of tetraphenylporphyrin iron, tetracarboxyphenylporphyrin iron, tetraaminophenylporphyrin iron, phthalocyanine iron, Fe(Phen)2, phenylporphyrin cobalt, tetracarboxyphenylporphyrin cobalt, tetraaminophenylporphyrin cobalt, phthalocyanine cobalt, Co(Phen)2, tetraphenylporphyrin manganese, tetracarboxyphenylporphyrin manganese, tetraaminophenylporphyrin manganese, phthalocyanine manganese, and Mn(Phen)2; The nitrogen-containing compound is selected from at least one of carbon nitride, melamine, cyanuric acid, urea, dicyandiamide, polypyrrole, and o-phenanthroline; The inactive gas atmosphere is selected from nitrogen atmosphere and / or inert gas atmosphere; The fluorinated monomer is selected from at least one of 4-fluorophenol, 3-fluorophenol, 3-(trifluoromethoxy)phenol, and 4-(trifluoromethyl)phenol.
4. The method according to claim 1, characterized in that, The mass ratio of the metal-nitrogen complex to the nitrogen-containing compound is 1:2 to 1:
20.
5. The method according to claim 1, characterized in that, The pyrolysis temperature is 300–900℃; The pyrolysis time is 1 to 6 hours; The calcination temperature is 130–160°C. The roasting time is 5 to 6 hours.
6. The method according to claim 1, characterized in that, After pyrolysis, it is etched with acid; The acid etching is performed using a 0.5–3 mol / L sulfuric acid aqueous solution at a temperature of 25–90 °C for 12–24 hours.
7. The method according to claim 1, characterized in that, The mass content of the metal element in the catalyst is 2-25 wt%. The metallic element is selected from at least one of iron, cobalt, and manganese.