Method for generating citral through continuous chemical combination based on microchannel reactor
Through the use of ultra -fine load metal catalysts in the micro -channel reactor to achieve the efficient and continuous synthesis of citizens, the problem of low catalytic conversion rate and complex reaction process in the existing process, and the rapid large amount of high -purity citizens can be achieved Production meets the economic and environmental requirements of modern industrial production.
Patent Information
- Application Number
- CN202411453267.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-17
- Publication Date
- 2025-01-24
Smart Images
Figure CN119350145A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of organic chemical industry and pharmaceutical intermediate synthesis, and specifically to the method of directly realizing the continuous synthesis of citral in a microchannel reactor by using a certain ultrafine supported metal catalyst. Background Art
[0002] Citral is a colorless to pale yellow oily liquid with a strong lemon aroma. 10 H 16 O, its fragrance helps to concentrate and improves people's mood. Citral has a wide range of uses, mainly used in the preparation of lemon, citrus and assorted fruit flavors, and is also the main raw material for the synthesis of ionone and vitamins.
[0003] Citral can be separated and extracted from plant essential oils and prepared by chemical synthesis. It is obtained by vacuum distillation of Litsea cubeba oil. This method has harsh process conditions, a long production process and a low extraction rate. Especially with the expansion of the use of citral, citral made from natural resources can no longer meet the needs of market development and is not suitable for large-scale production. The chemical synthesis method can be divided into the dehydrogenation linalool transposition method and the condensation rearrangement synthesis method of 2 C5 enols and enal. At present, the industrial production of citral is mainly chemical synthesis. The reaction process is as follows: Figure 1 shown.
[0004] The synthesis method based on the condensation and rearrangement of two C5 enols and enals uses isopentenol and isopentenal as raw materials, condenses to obtain acetal, and then obtains citral through cracking and rearrangement. Although the yield exceeds 95%, this process is an intermittent production process, which has the disadvantages of large floor space, long synthesis time, and complicated synthesis steps.
[0005] A microchannel reactor is a three-dimensional structural element that can be used for chemical reactions and is manufactured with a solid matrix using special micromachining technology. Microchannel reactors usually contain small channel sizes (equivalent diameter less than 500 μm) and channel diversity. Fluids flow in these channels and the required reactions are required to occur in these channels. This results in a very large surface area / volume ratio in microstructured chemical equipment, which can promote process intensification and miniaturization of chemical systems, improve resource utilization, save energy and reduce consumption, and fundamentally solve technical problems such as incomplete reactions and explosiveness in traditional processes. It has great advantages in terms of transfer characteristics, safety and controllability.
[0006] In summary, in the process of preparing citral by the batch method, there are disadvantages such as low catalytic conversion rate, easy occurrence of side reactions, affecting product yield, acidic substances are corrosive to equipment, high requirements for equipment materials, increased equipment investment in industrial production, complex reaction process, and cumbersome equipment cleaning. In addition, the reaction solution is acidic when an acidic catalyst is used for catalytic reaction. After the reaction, the reaction solution needs to be neutralized, which will produce a large amount of wastewater, which does not conform to the development concept of economic and environmental protection in modern industrial production.
[0007] Therefore, there is an urgent need to develop a citral synthesis system with high activity, good selectivity, easy separation, high production efficiency, economy and environmental protection based on efficient catalyst technology and making full use of the advantages of microchannel reactors. Summary of the invention
[0008] The batch synthesis process system of citral has the disadvantages of low conversion rate, low selectivity, complex reaction process, cumbersome multi-step reaction treatment and long reaction time. The present invention intends to reduce the complex multi-step process to a continuous reaction by combining ultrafine supported metal catalyst with microchannel reaction technology, so as to efficiently prepare high-purity citral.
[0009] In order to achieve the above object, the present invention adopts the following technical solution:
[0010] The invention discloses a method for continuously synthesizing citral in a microchannel reactor, and utilizes an ultrafine modified metal-supported catalyst to realize efficient continuous synthesis of citral from acetal in a microchannel reactor.
[0011] The metal elements in the ultrafine modified metal catalyst include one or more common metals or transition metals such as iron, sodium, potassium, aluminum, magnesium, copper, zinc, titanium, gold, platinum, palladium, nickel, rhodium, osmium, ruthenium, vanadium, cobalt, chromium, and molybdenum.
[0012] The particle size of the ultrafine modified metal catalyst is not higher than 0.1 μm.
[0013] The carrier of the ultrafine modified metal catalyst is a nanometer material.
[0014] Preferably, in the microchannel synthesis process of citral, the mass ratio of acetal to catalyst is: acetal: catalyst = 64:1, the raw material flow rate is not less than 0.2 ml / min, the preheating temperature is 150-200°C, the reaction temperature is controlled at 250-300°C, the continuous feeding time is 0-72h, and the cooling temperature is 160-180°C.
[0015] Preferably, a catalyst is added to the reaction raw materials, mixed and fed together, and the citral product is directly obtained after staged cooling. Figure 2 shown.
[0016] The beneficial effects of the present invention are as follows:
[0017] The present invention reduces a complex multi-step process to a continuous reaction by combining an ultrafine supported metal catalyst with a microchannel reaction technology, reduces a complex multi-step process to a continuous reaction in one reactor, and can quickly and massively obtain high-purity citral. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 Schematic diagram of the reaction process of citral.
[0019] Figure 2 Schematic diagram of the method for continuously synthesizing citral based on a microchannel reactor. DETAILED DESCRIPTION
[0020] The following description is only a preferred embodiment of the present invention and does not limit the present invention. For those skilled in the art, various changes and variations are possible. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
[0021] Example 1
[0022] The catalyst was added to the acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.2 ml / min. The first module of the microchannel was preheated (180°C) and then entered the reaction module (250°C). The cooling and collection section was 160-180°C. The reaction was continued for 3.0 hours to obtain citral with a purity of 91.1% and a yield of 92.5%.
[0023] Example 2
[0024] Catalyst was added to acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.2 ml / min, the first module of the microchannel was preheated (150°C), and then entered the reaction module (250°C), the cooling and collection section was 160-180°C, and the reaction was continued for 3.0 hours to obtain citral with a purity of 90.0% and a yield of 88.5%.
[0025] Example 3
[0026] Catalyst was added to acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.2 ml / min, the first module of the microchannel was preheated (180°C), and then entered the reaction module (280°C), the cooling and collection section was 160-180°C, and the reaction was continued for 3.0 hours to obtain citral with a purity of 96.0% and a yield of 97.3%.
[0027] Example 4
[0028] The catalyst was added to the acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.2 ml / min. The first module of the microchannel was preheated (200°C), and then entered the reaction module (280°C). The cooling and collection section was 160-180°C. The reaction was continued for 3.0 hours to obtain citral with a purity of 91.8% and a yield of 93.3%.
[0029] Example 5
[0030] The catalyst was added to the acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.2 ml / min. The first module of the microchannel was preheated (180°C) and then entered the reaction module (300°C). The cooling and collection section was 160-180°C. The reaction was continued for 3.0 hours to obtain citral with a purity of 91.3% and a yield of 91.9%.
[0031] Example 6
[0032] Catalyst was added to acetal in a certain ratio (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.2 ml / min, the first module of the microchannel was preheated (180°C), and then entered the reaction module (280°C), the cooling and collection section was 160-180°C, and the reaction was continued for 24 hours to obtain citral with a purity of 94.7% and a yield of 95.5%.
[0033] Example 7
[0034] Catalyst was added to acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.2 ml / min, the first module of the microchannel was preheated (180°C), and then entered the reaction module (280°C), the cooling and collection section was 160-180°C, and the reaction was continued for 72 hours to obtain citral with a purity of 92.7% and a yield of 93.5%.
[0035] Example 8
[0036] Catalyst was added to acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.5 ml / min, the first module of the microchannel was preheated (180°C), and then entered the reaction module (280°C), the cooling and collection section was 160-180°C, and the reaction was continued for 3 hours to obtain citral with a purity of 90.0% and a yield of 92.4%.
[0037] Example 9
[0038] Catalyst was added to acetal in a certain proportion (acetal weight: catalyst weight = 64:1), mixed and pumped in at a rate of 0.3 ml / min, the first module of the microchannel was preheated (180°C), and then entered the reaction module (280°C), the cooling and collection section was 160-180°C, and the reaction was continued for 3 hours to obtain citral with a purity of 92.0% and a yield of 92.3%.
[0039] Summary of Examples
[0040]
[0041] As can be seen from the table of Examples 1-9, the intermittent synthesis process system for citral has the disadvantages of low conversion rate, low selectivity, complex reaction process, cumbersome multi-step reaction treatment, and long reaction time. The present invention intends to reduce the complex multi-step process to a continuous reaction time by at least 50% by combining ultrafine supported metal catalysts with microchannel reaction technology, and can efficiently prepare high-purity citral.
Claims
1. A method for continuously synthesizing citral based on a microchannel reactor, characterized in that: Using ultrafine modified metal-supported catalysts, efficient and continuous synthesis of acetal to citral was achieved in a microchannel reactor.
2. The method according to claim 1, characterized in that: The metal elements in the ultrafine modified metal catalyst include one or more common metals or transition metals such as iron, sodium, potassium, aluminum, magnesium, copper, zinc, titanium, gold, platinum, palladium, nickel, rhodium, osmium, ruthenium, vanadium, cobalt, chromium, and molybdenum.
3. The method according to claim 1, characterized in that The particle size of the ultrafine modified metal catalyst is not higher than 0.1 μm.
4. The method according to claim 3, characterized in that The carrier of the ultrafine modified metal catalyst is a nanometer material.
5. The method according to claim 1 or 3, characterized in that: The cracking and two-step rearrangement reactions are both carried out in a microchannel reactor.
6. The method according to claim 1 or 3, characterized in that: The mass ratio of raw material acetal to ultrafine modified metal-supported catalyst is: acetal: catalyst = 64:
1.
7. The method according to claim 6, characterized in that The raw material flow rate is not less than 0.2 ml / min, the preheating temperature is 150-200°C, the reaction temperature is controlled at 250-300°C, the continuous feeding time is 0-72h, and the cooling temperature is 160-180°C.
8. The method according to claim 7, characterized in that An ultrafine modified metal-supported catalyst is added to the reaction raw materials, mixed and fed together, and the citral product is directly obtained after staged cooling.