Preparation method of niobium oxide / beta supported catalyst and application thereof in synthesis of carvacol
By using a NiO/Beta supported catalyst to catalyze the reaction of o-cresol and isopropanol, the problems of catalyst toxicity and environmental protection in the existing carvacrol synthesis have been solved, and a highly efficient and safe carvacrol synthesis process has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 江苏宏邦化工科技有限公司
- Filing Date
- 2024-05-30
- Publication Date
- 2026-08-04
AI Technical Summary
Existing methods for synthesizing carvacrol suffer from problems such as catalyst toxicity, cumbersome reaction steps, excessive wastewater and waste salt production, and unsafe raw materials, resulting in high costs and significant environmental pressure.
Using a NiO/Beta supported catalyst, a simple and safe preparation method was adopted to catalyze the reaction of o-cresol and isopropanol to synthesize carvacrol, taking advantage of its special pore structure and high specific surface area. The reaction was carried out at 240~400℃ and atmospheric pressure.
It achieves high reaction conversion rate and selectivity, reduces production costs, avoids wastewater generation, has a simple and safe process, and the catalyst is regenerable.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic synthesis technology and relates to the preparation of catalysts for the synthesis of carvacrol, specifically to a method for preparing a NiO / Beta supported catalyst and its application in the synthesis of carvacrol. Background Technology
[0002] Carvacrol is a pale yellow to colorless viscous oily liquid with the chemical formula C. 10 H 14 O, with a molecular weight of 150, carvacrol possesses properties such as clearing heat, resolving dampness, relieving summer heat, and inhibiting and killing bacteria. Carvacrol is one of the main antibacterial components in natural oregano oil and mountain pepper oil. Due to its broad-spectrum antibacterial activity, safety, and extremely low residue levels in animals, it is used to treat dysentery and coccidiosis in chickens and piglets. Oregano oil is one of the feed additives approved for use by the Ministry of Agriculture of my country. It is a safe, efficient, green, and purely natural active ingredient with a high content of active ingredients, without any incompatibilities. However, there is currently a huge market gap in the domestic production capacity of natural oregano oil, making the development of a low-cost carvacrol synthesis process highly promising.
[0003] Currently, there are two main methods for synthesizing carvacrol. One method uses carvacrol and its derivatives as raw materials, synthesizing carvacrol through isomerization, rearrangement, and dehydrogenation reactions under the action of strong acids or metal catalysts. For example, CN107365247A uses Cu / Cr catalytic dehydrogenation isomerization of dihydrocarvacrol to synthesize carvacrol. In this method, dihydrocarvacrol is a byproduct of the carvacrol synthesis process, with a very small yield, and the catalyst contains chromium, which is toxic and unsafe. Another example is CN116554004A, which uses 2,3-epoxypinene as raw material and obtains carvacrol through a three-step reaction of hydrolysis isomerization, oxidation, and acidification. The first step product of this method is water and carvacrol alcohol, which have high melting points and are difficult to handle. Furthermore, this method involves a three-step reaction, resulting in numerous steps and a significant reduction in process cost. The other method uses o-cresol as raw material and synthesizes carvacrol through Friedel-Crafts alkylation reactions with isopropanol, propylene, or 2-halopropane. For example, CN109851479A describes the synthesis of carvacrol using o-cresol and isopropanol as raw materials, dichloromethane as solvent, and aluminum trichloride as catalyst. This method involves a low reaction temperature, but it generates large amounts of wastewater and waste salt, posing a significant environmental burden. Another example is CN113896617A, which uses o-cresol and propylene as raw materials and a modified Al2O3 / CuAl2O4 composite material as catalyst. While this method is simple, the propylene used is a gaseous substance, posing significant safety hazards during transportation and storage. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a NiO / Beta supported catalyst. This invention provides a simple and safe method to obtain a NiO / Beta supported catalyst with a unique pore structure, excellent shape selectivity, large specific surface area, strong catalytic activity, and regenerability. When used for the catalytic synthesis of carvacrol, it utilizes two common raw materials, o-cresol and isopropanol, in a simple and safe process with high reaction conversion and selectivity.
[0005] This invention is achieved through the following technical solution:
[0006] A method for preparing a NiO / Beta supported catalyst includes the following steps:
[0007] (1) Prepare a certain amount of nickel nitrate aqueous solution, impregnate it with an equal volume of Beta molecular sieve, and then dry and calcine it to obtain the catalyst precursor;
[0008] (2) The catalyst precursor and binder are added to a pulverizer and crushed and mixed at high speed. Then water and glycerol are added to the mixture and stirred and kneaded. After the mixture is formed into a ball, the material is passed through an extruder to obtain a columnar catalyst. Finally, the columnar NiO / Beta supported catalyst is obtained through natural air drying, baking and calcination processes.
[0009] A further improvement to the present invention is as follows:
[0010] The Beta molecular sieve is a commercially available hydrogen-type Beta molecular sieve, with a silica-to-alumina ratio between 20 and 100, and a mass ratio of nickel nitrate to Beta molecular sieve of 0.01 to 0.3:1.
[0011] Furthermore, the drying process in step (1) is as follows: the impregnated molecular sieve is placed in a forced-air drying oven and baked at 80~120℃ for 10~14 h; the calcination process is as follows: the dried material is placed in a muffle furnace and heated at a rate of 1.2℃ / min, and calcined at 450~550℃ for 2~5 h.
[0012] Furthermore, the binder is one or a mixture of two or more of starch, guar gum, palygorskite, or silica sol.
[0013] Preferably, the adhesive is palygorskite.
[0014] Furthermore, the mass ratio of the Beta molecular sieve, binder, water, and glycerol is 1:0.01-0.1:0.8-1.2:0.01-0.0.03.
[0015] Furthermore, the columnar NiO / Beta supported catalyst has the following dimensions: diameter 0.5~2mm and length 1~3cm.
[0016] Furthermore, in step (2), the natural air drying process is as follows: place the extrudate in a cool and ventilated place and air dry for 48 hours; the drying process is as follows: put the air-dried catalyst into a forced-air drying oven and dry at 120°C for 8 hours; the calcination process is as follows: put the dried material into a muffle furnace and calcin at 500°C for 4 hours, with a temperature gradient of 1.2°C / min.
[0017] A further improvement of the present invention is as follows:
[0018] The application of the NiO / Beta supported catalyst prepared by the above method in the synthesis of carvacrol is characterized by the following steps: the NiO / Beta supported catalyst is loaded into a fixed-bed reactor, and after purging with nitrogen, o-cresol and isopropanol are mixed and injected into the reactor using an injection pump. The reaction temperature is between 240 and 400°C, and the reaction is carried out under atmospheric pressure.
[0019] Furthermore, the molar ratio of o-cresol to isopropanol is 1~3:1, the reaction temperature is 240-400℃, and the mass hourly space velocity is 0.2-1.3g / h.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0021] (1) This method is simple and safe.
[0022] (2) This method does not require a washing step, does not generate wastewater, and does not pose an environmental risk.
[0023] (3) The catalyst used in this method is an inexpensive metal that can be regenerated, which greatly reduces production costs. Detailed Implementation
[0024] The present invention will now be described in detail with reference to specific embodiments.
[0025] Example 1: Preparation of NiO / Beta supported catalyst
[0026] Take 100g of hydrogen-form Beta molecular sieve powder, prepare 60 mL of 1 mol / L nickel nitrate, mix slowly, stir evenly, let stand for adsorption for 8 h, dry at 120℃ for 12 h, crush and grind, then calcine at 450℃ for 3 h with the temperature increased at 1.2℃ / min.
[0027] All impregnated and supported catalyst precursors were mixed with 10 g of palygorskite and intermittently stirred at high speed in a mixer for 10 min. Then, 90 g of water and 5 g of glycerol were added to the mixture, and stirring and kneading continued for 30 min. The mixture was then pressed into small balls of about 5 cm in diameter and fed into an extruder. The resulting columnar catalyst was placed in a cool, ventilated place to air dry for 48 h, and then dried in a blower dryer for 24 h at a constant temperature of 120℃. Finally, the dried precursor was placed in a muffle furnace and calcined at 500℃ for 4 h to obtain 93.75 g of the finished catalyst.
[0028] Example 2: Synthesis of carvacrol
[0029] 45g of the catalyst prepared in Example 1 was loaded into a fixed-bed reactor. o-cresol and isopropanol were mixed at a molar ratio of 1:2. The mixture was pumped into the reactor using an injection pump at a flow rate of 1ml / min. The reaction temperature was 250℃. The material at the reactor outlet was tested and showed that the o-cresol conversion rate was 89.52% and the carvacrol selectivity was 97.55%.
[0030] Example 3: Preparation of NiO / Beta supported catalyst
[0031] Take 100 g of hydrogen-form Beta molecular sieve powder, prepare 60 mL of 0.5 mol / L nickel nitrate, mix slowly, stir evenly, let stand for adsorption for 8 h, dry at 120℃ for 12 h, crush and grind, then calcine at 500℃ for 3 h with the temperature increased at 1.2℃ / min.
[0032] All the impregnated and supported catalyst precursors were mixed with 10 g of silica sol and intermittently stirred at high speed in a mixer for 10 min. Then, 90 g of water and 5 g of glycerol were added to the mixture, and stirring and kneading continued for 30 min. The mixture was then pressed into small balls of about 5 cm in diameter and fed into an extruder. The resulting columnar catalyst was placed in a cool, ventilated place to air dry for 48 h, and then dried in a blower dryer for 24 h at a constant temperature of 120℃. Finally, the dried precursor was placed in a muffle furnace and calcined at 500℃ for 4 h to obtain 92.15 g of the finished catalyst.
[0033] Example 4: Synthesis of carvacrol
[0034] 45g of the catalyst prepared in Example 3 was loaded into a fixed-bed reactor. o-cresol and isopropanol were mixed at a molar ratio of 1:2. The mixture was pumped into the reactor using an injection pump at a flow rate of 1ml / min. The reaction temperature was 290℃. The material at the reactor outlet was tested and showed that the o-cresol conversion rate was 84.13% and the carvacrol selectivity was 98.83%.
[0035] Comparative Example 1
[0036] Compared to Example 1, nickel nitrate was replaced with copper nitrate, while all other steps remained the same, resulting in a CuO / Beta supported catalyst.
[0037] The prepared catalyst was used in the synthesis of carvacrol under the same process conditions as in Example 2, with an o-cresol conversion rate of 77.15% and a carvacrol selectivity of 84.12%.
[0038] Comparative Example 2
[0039] Compared to Example 1, nickel nitrate was replaced with magnesium nitrate, while all other steps remained the same, resulting in a MgO / Beta supported catalyst.
[0040] The prepared catalyst was used in the synthesis of carvacrol under the same process conditions as in Example 2, with an o-cresol conversion rate of 75.88% and a carvacrol selectivity of 85.22%.
[0041] Comparative Example 3
[0042] Compared to Example 1, nickel nitrate was not added, but all other steps were the same, resulting in strip-shaped hydrogen-type Beta molecular sieves.
[0043] The prepared catalyst was used in the synthesis of carvacrol under the same process conditions as in Example 2, with an o-cresol conversion rate of 88.35% and a carvacrol selectivity of 83.16%.
[0044] As shown in Example 1 and Comparative Examples 1-3, compared with other metals, the addition of nickel changes the original pore structure of Beta molecular sieve, which is more conducive to the passage of carvacrol. Therefore, the shape selectivity is significantly enhanced. Furthermore, the addition of nickel does not affect the acidity of the molecular sieve itself, and it can be used for a long time. The small-scale device ran continuously for 120 hours, and the o-cresol conversion rate did not show a significant downward trend.
[0045] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. The application of a NiO / Beta supported catalyst in the synthesis of carvacrol, characterized in that, The process includes the following steps: NiO / Beta supported catalyst is loaded into a fixed-bed reactor, and after nitrogen purging, o-cresol and isopropanol are mixed and injected into the reactor using an injection pump. The reaction temperature is between 240 and 400°C, and the reaction is carried out under atmospheric pressure. The NiO / Beta supported catalyst was prepared by the following steps: (1) Prepare a certain amount of nickel nitrate aqueous solution, immerse an equal volume of Beta molecular sieve in the nickel nitrate aqueous solution, and dry and calcine after immersion to obtain the catalyst precursor; (2) The catalyst precursor and binder are added to a pulverizer and crushed and mixed at high speed. Then water and glycerol are added to the mixture and stirred and kneaded. After the mixture is formed into a ball, the material is passed through an extruder to obtain a columnar catalyst. Finally, the columnar NiO / Beta supported catalyst is obtained through natural air drying, baking and calcination processes.
2. The application according to claim 1, characterized in that: The Beta molecular sieve is a commercially available hydrogen-type Beta molecular sieve, with a silica-to-alumina ratio between 20 and 100, and a mass ratio of nickel nitrate to Beta molecular sieve of 0.01 to 0.3:
1.
3. The application according to claim 1, characterized in that: The drying process described in step (1) is as follows: the impregnated molecular sieve is placed in a forced-air drying oven and dried at 80~120℃ for 10~14 h; the calcination process is as follows: the dried material is placed in a muffle furnace and heated at a rate of 1.2℃ / min and calcined at 450~550℃ for 2~5 h.
4. The application according to claim 1, characterized in that: The binder is one or a mixture of two or more of starch, guar gum, palygorskite, or silica sol.
5. The application according to claim 4, characterized in that: The adhesive is palygorskite.
6. The application according to claim 1, characterized in that: The mass ratio of the Beta molecular sieve, binder, water, and glycerol is 1:0.01-0.1:0.8-1.2:0.01-0.0.
03.
7. The application according to claim 1, characterized in that: The columnar NiO / Beta supported catalyst has the following dimensions: diameter 0.5~2mm and length 1~3cm.
8. The application according to claim 1, characterized in that: In step (2), the natural air-drying process is as follows: place the extrudate in a cool and ventilated place and air-dry for 48 hours; the drying process is as follows: put the air-dried catalyst into a forced-air drying oven and dry at 120°C for 8 hours; the calcination process is as follows: put the dried material into a muffle furnace and calcin at 500°C for 4 hours with a heating rate of 1.2°C / min.
9. The application according to claim 1, characterized in that: The molar ratio of o-cresol to isopropanol is 1~3:1, and the mass hourly space velocity is 0.2-1.3 g / h.