Dehydrogenation catalyst as well as preparation method and application thereof in synthesis of carvacrol

Abstract

The invention belongs to the technical field of organic synthesis, and particularly discloses a dehydrogenation catalyst and a preparation method and application thereof in carvacrol synthesis, the dehydrogenation catalyst takes a gamma-aluminum oxide-molecular sieve composite product as a carrier, takes Pd as a main active component, takes Ni and Mn as auxiliaries, and comprises the following components in percentage by mass: 3-6% of Pd, 0.3-1.0% of Ni and the balance of Mn. The mass percent of Mn is 1-3%, and the balance is the gamma-aluminum oxide-molecular sieve composite carrier. The catalyst has a good dehydrogenation effect in carvacrol preparation through carvacrol dehydrogenation, continuous reaction is adopted in the reaction, safety, controllability and no pollution are achieved, 99.5% of finished products can be obtained through simple rectification of carvacrol flowing out of a reactor outlet, the reaction efficiency is greatly improved, no waste water is generated in the reaction, and the method is suitable for industrial production. And new social benefits and economic benefits are created while the environmental protection problem in production is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis and relates to the preparation of a dehydrogenation reaction catalyst, in particular to a dehydrogenation catalyst and a preparation method thereof and application of the dehydrogenation catalyst in synthesizing carvacrol. Background Art

[0002] Carvacrol is a colorless to light yellow thick oily liquid with the smell of thymol. As a commonly used food additive and fragrance, it has the characteristics of low toxicity and naturalness, and is approved as a safe food additive in the United States and Europe. Natural carvacrol is mainly found in a variety of Lamiaceae plants, such as thyme and oregano. Carvacrol has a wide range of functions and application values. It has a good growth inhibitory effect on bacteria, yeast, fungi, insects and mites by destroying and changing the cell membrane structure of pathogenic bacteria or the structure of mycelium, or effectively inhibiting the activity of conidia. It is an effective ingredient of thyme for promoting blood circulation and removing blood stasis, and achieves platelet activation by mediating the signal transduction pathway of RhoA / Rho-kinase coupled to anti-thromboxane via G13 protein. These effects make it widely used as a natural antibacterial preservative in food, medicine, cosmetics and other products.

[0003] At present, there are two main methods for synthesizing carvacrol: one is to use carvone as a raw material and synthesize carvacrol by aromatization under the action of a strong acid or a metal catalyst. For example, CN101475448A reported an example of using an organic acid or an inorganic acid as a main catalyst and PEG-400 or PEG-600 as a cocatalyst to promote the synthesis of carvacrol by rearrangement of carvone molecules; in addition, Linstead, RP reported the reaction of synthesizing carvacrol by dehydrogenation isomerization of carvone catalyzed by metal palladium (Journal of the Chemical Society, 1940, 1139-1147). The advantages of this type of method are good reaction selectivity and high yield, but the raw material carvone itself is a spice product with a high price, which greatly reduces the cost advantage of this process. The second method is to use o-methylphenol as a raw material and synthesize carvacrol through a Friedel-Crafts reaction with isopropanol or 2-halopropane. For example, patent CN1488615 reports a method for synthesizing carvacrol by promoting the reaction of o-methylphenol with 2-chloropropane using aluminum chloride or ferric chloride. However, this method generates a large amount of aluminum salt and iron salt solid waste, causing environmental pollution and limiting its further application in production. Summary of the invention

[0004] In view of the deficiencies of the prior art, an object of the present invention is to provide a dehydrogenation catalyst. By using the catalyst, carveol can be directly converted into carvacrol through a simple dehydrogenation reaction in one step, thereby greatly improving the production efficiency of carvacrol. Another object of the present invention is to provide a method for preparing the dehydrogenation catalyst.

[0005] The present invention is achieved through the following technical solutions: A dehydrogenation catalyst, which uses a γ-alumina-molecular sieve composite product as a carrier, Pd as a main active ingredient, and Ni and Mn as additives, wherein the mass percentage of Pd is 3-6%, the mass percentage of Ni is 0.3-1.0%, the mass percentage of Mn is 1-3%, and the rest is the γ-alumina-molecular sieve composite carrier.

[0006] A further improvement of the present invention is: A method for preparing a dehydrogenation catalyst comprises the following steps: Step 1: Mix γ-alumina and molecular sieve, add deionized water and stir evenly, filter, dry, and calcine to obtain a γ-alumina-molecular sieve composite carrier; Step 2: dissolve the metal Pd compound, metal Ni compound, metal Mn compound and complexing agent in deionized water to obtain a mixed solution, immerse the γ-alumina-molecular sieve composite carrier in the obtained solution, and after immersion for 3-5 hours, remove the solvent, dry, calcine and reduce to obtain the PdNiMn / γ-alumina-molecular sieve dehydrogenation catalyst.

[0007] A further improvement of the present invention is: The mass ratio of γ-alumina, molecular sieve and deionized water in step 1 is (0.2-0.6): (1-1.5): (2-5).

[0008] Furthermore, the molecular sieve is selected from ZSM-5 or Beta.

[0009] Furthermore, in step 1, the drying temperature is 110-120° C., the drying time is 4-8 hours, the calcination temperature is 500-600° C., and the calcination time is 5-7 hours.

[0010] Furthermore, the complexing agent in step 2 is one or a mixture of two or more of sodium tartrate, citric acid or disodium ethylenediaminetetraacetate, and the concentration of the complexing agent is 0.2 mol / L-2.5 mol / L.

[0011] Furthermore, the metal Pd compound in step 2 is one or a mixture of two or more of palladium chloride, palladium sulfate or palladium nitrate; And / or, the metal Ni compound is one or a mixture of two or more of nickel chloride, nickel sulfate or nickel nitrate; And / or, the metal Mn compound is one or a mixture of two or more of manganese chloride, manganese sulfate or manganese nitrate.

[0012] Furthermore, in step 2, the drying temperature is 110-120° C., the drying time is 4-8 hours, the calcination temperature is 500-800° C., and the calcination time is 5-10 hours.

[0013] A further improvement of the present invention is: The invention discloses an application of a dehydrogenation catalyst in the synthesis of carvacrol, comprising the following steps: adding a PdNiMn / γ-alumina-molecular sieve dehydrogenation catalyst into a tubular reactor, pumping carvacrol into the reactor at a uniform speed by using a metering pump, and allowing crude carvacrol to flow out after a reaction, and the crude carvacrol can be subjected to simple distillation to obtain a finished carvacrol product.

[0014] The reaction equation is as follows:

[0015] Further, the loading amount of the dehydrogenation catalyst in the tubular reactor is 600 g / L; And / or, the temperature of the residence reaction is 200-250° C., and the residence time of the residence reaction is 0.5-1 h.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention uses a self-made novel PdNiMn / γ-alumina-molecular sieve granular catalyst as a dehydrogenation catalyst to catalyze the dehydrogenation of carveol to prepare carvacrol. In the reaction of the invention, the conversion rate of carveol is high, and the yield of carvacrol is significantly higher than that of common catalysts on the market. In addition, the catalyst has a long service life and can be continuously used for more than 500 hours in a tubular reactor. No wastewater is generated during the reaction, and the reaction is green and pollution-free. Production in a continuous device can greatly improve the production capacity of carvacrol while ensuring safety. DETAILED DESCRIPTION

[0017] The present invention is described in detail below in conjunction with specific embodiments.

[0018] Example 1: Preparation of Dehydrogenation Catalyst I (1) Weigh 10 g of γ-alumina and 30 g of ZSM or Beta molecular sieve, mix them, add deionized water and stir them evenly, filter them, dry them at 110-120°C for 6 h, and then calcine them at 550°C for 6 h to obtain a γ-alumina-molecular sieve composite carrier; (2) Weigh 3.4 g of palladium chloride, 0.35 g of nickel sulfate, 1.18 g of manganese sulfate and 4.0 g of citric acid and dissolve them in 200 g of deionized water. Stir at room temperature until they are completely dissolved. (3) The γ-alumina-molecular sieve composite carrier in (1) is added to the solution of (2) and impregnated for 4 hours, then evaporated to remove water. After removal of water, the material is dried and spheroidized at 110-120°C for 6 hours, calcined at 600°C for 7 hours, and finally the calcined material is placed in a tubular furnace at 400°C in a hydrogen atmosphere for reduction for 6 hours to obtain a granular catalyst I.

[0019] (4) The contents of active components in the obtained catalyst are: Pd 4.6wt%, Ni 0.3wt%, Mn 1.0wt%; the rest is γ-alumina-molecular sieve composite carrier.

[0020] Example 2: Preparation of Dehydrogenation Catalyst II (1) Weigh 10 g of γ-alumina and 30 g of ZSM or Beta molecular sieve, mix them, add deionized water and stir them evenly, filter them, dry them at 110-120°C for 6 h, and then calcine them at 550°C for 6 h to obtain a γ-alumina-molecular sieve composite carrier; (2) Weigh 3.4 g of palladium chloride, 0.35 g of nickel sulfate, 3.54 g of manganese sulfate and 4.0 g of citric acid and dissolve them in 200 g of deionized water. Stir at room temperature until they are completely dissolved. (3) The γ-alumina-molecular sieve composite carrier in (1) is added to the solution of (2) and impregnated for 4 hours, then evaporated to remove water. After removal of water, the material is dried and spheroidized at 110-120°C for 6 hours, calcined at 600°C for 7 hours, and finally the calcined material is placed in a tubular furnace at 400°C in a hydrogen atmosphere for reduction for 6 hours to obtain a granular catalyst II.

[0021] (4) The contents of active components in the obtained catalyst are: Pd 4.6wt%, Ni 0.3wt%, Mn 3.0wt%; the rest is γ-alumina-molecular sieve composite carrier.

[0022] Example 3: Preparation of Dehydrogenation Catalyst III (1) Weigh 10 g of γ-alumina and 30 g of ZSM or Beta molecular sieve, mix them, add deionized water and stir them evenly, filter them, dry them at 110-120°C for 6 h, and then calcine them at 550°C for 6 h to obtain a γ-alumina-molecular sieve composite carrier; (2) Weigh 3.4 g of palladium chloride, 1.16 g of nickel sulfate, 1.18 g of manganese sulfate and 4.0 g of citric acid and dissolve them in 200 g of deionized water. Stir at room temperature until they are completely dissolved. (3) The γ-alumina-molecular sieve composite carrier in (1) is added to the solution of (2) and impregnated for 4 hours, then evaporated to remove water. After removal of water, the material is dried and spheroidized at 110-120°C for 6 hours, calcined at 600°C for 7 hours, and finally the calcined material is placed in a tubular furnace at 400°C in a hydrogen atmosphere for reduction for 6 hours to obtain a granular catalyst III.

[0023] (4) The contents of active components in the obtained catalyst are: Pd 4.6wt%, Ni 1.0wt%, Mn 1.0wt%; the rest is γ-alumina-molecular sieve composite carrier.

[0024] Example 4: Preparation of Dehydrogenation Catalyst IV (1) Weigh 10 g of γ-alumina and 30 g of ZSM or Beta molecular sieve, mix them, add deionized water and stir them evenly, filter them, dry them at 110-120°C for 6 h, and then calcine them at 550°C for 6 h to obtain a γ-alumina-molecular sieve composite carrier; (2) Weigh 3.4 g of palladium chloride, 1.16 g of nickel sulfate, 3.54 g of manganese sulfate and 4.0 g of citric acid and dissolve them in 200 g of deionized water. Stir at room temperature until they are completely dissolved. (3) The γ-alumina-molecular sieve composite carrier in (1) is added to the solution of (2) and impregnated for 4 hours, then evaporated to remove water. After removal of water, the material is dried and spheroidized at 110-120°C for 6 hours, calcined at 600°C for 7 hours, and finally the calcined material is placed in a tubular furnace at 400°C under a hydrogen atmosphere for reduction for 6 hours to obtain a granular catalyst IV.

[0025] (4) The contents of active components in the obtained catalyst are: Pd 4.6wt%, Ni 1.0wt%, Mn 3.0wt%; the rest is γ-alumina-molecular sieve composite carrier.

[0026] Example 5: Preparation of Dehydrogenation Catalyst V (1) Weigh 10 g of γ-alumina and 30 g of ZSM or Beta molecular sieve, mix them, add deionized water and stir them evenly, filter them, dry them at 110-120°C for 6 h, and then calcine them at 550°C for 6 h to obtain a γ-alumina-molecular sieve composite carrier; (2) Weigh 3.4 g of palladium chloride, 1.16 g of nickel sulfate, 1.18 g of manganese sulfate and 4.0 g of citric acid and dissolve them in 200 g of deionized water. Stir at room temperature until they are completely dissolved. (3) The γ-alumina-molecular sieve composite carrier in (1) is added to the solution in (2) and immersed for 4 hours, and then evaporated to remove water. After the water is removed, the material is extruded, dried at 110-120°C for 6 hours, and calcined at 600°C for 7 hours. Finally, the calcined material is placed in a tubular furnace at 400°C for reduction under a hydrogen atmosphere for 6 hours to obtain a cylindrical catalyst V.

[0027] (4) The contents of active components in the obtained catalyst are: Pd 4.6wt%, Ni 1.0wt%, Mn 3.0wt%; the rest is γ-alumina-molecular sieve composite carrier. Example 6

[0028] (1) The granular catalyst I prepared in Example 1 was loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 230°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 947.6 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 97%. Example 7

[0029] (1) The granular catalyst II prepared in Example 2 was loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 230°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 945.6 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 96.8%. Example 8

[0030] (1) The granular catalyst III prepared in Example 3 was loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 230°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 942.7 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 96.5%. Example 9

[0031] (1) The granular catalyst IV prepared in Example 4 was loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 230°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 949.54 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 97.2%. Example 10

[0032] (1) The cylindrical catalyst V prepared in Example 5 was loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 230°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 923.16 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 94.5%. Embodiment 11

[0033] (1) A conventional Pd / aluminum oxide granular catalyst on the market is loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 230°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 901.67 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 92.3%. Example 12

[0034] (1) A conventional granular copper-carbon dehydrogenation catalyst on the market is loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 230°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 815.70 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 83.5%. Example 13

[0035] (1) The granular catalyst III prepared in Example 3 was loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 200°C; (3) 1000 g of carveol was passed through a tubular reactor at a uniform speed by a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor was controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 947.60 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 97.0%. Embodiment 14

[0036] (1) The granular catalyst III prepared in Example 3 was loaded into a tubular reactor at a loading density of 600 g / L; (2) Controlling the temperature of the tubular reactor at 250°C; (3) passing carveol through a tubular reactor at a uniform speed using a metering pump to undergo a dehydrogenation reaction, and the residence time of carveol in the tubular reactor is controlled to be 0.5 h; (4) The material coming out of the tubular reactor is the crude carvacrol. Simple distillation can yield 942.7 g of the finished carvacrol. The unreacted raw material and the fore-distillate are returned to the tubular reactor for reaction. The total yield of this reaction is 96.5%.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A dehydrogenation catalyst, characterized in that The dehydrogenation catalyst uses a γ-alumina-molecular sieve composite product as a carrier, Pd as a main active ingredient, and Ni and Mn as additives, wherein the mass percentage of Pd is 3-6%, the mass percentage of Ni is 0.3-1.0%, the mass percentage of Mn is 1-3%, and the rest is the γ-alumina-molecular sieve composite carrier.

2. A method for preparing a dehydrogenation catalyst as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Mix γ-alumina and molecular sieve, add deionized water and stir evenly, filter, dry, and calcine to obtain a γ-alumina-molecular sieve composite carrier; Step 2: dissolve the metal Pd compound, metal Ni compound, metal Mn compound and complexing agent in deionized water to obtain a mixed solution, immerse the γ-alumina-molecular sieve composite carrier in the obtained solution, and after immersion for 3-5 hours, remove the solvent, dry, calcine and reduce to obtain the PdNiMn / γ-alumina-molecular sieve dehydrogenation catalyst.

3. A method for preparing a dehydrogenation catalyst according to claim 2, characterized in that: The mass ratio of γ-alumina, molecular sieve and deionized water in step 1 is (0.2-0.6): (1-1.5): (2-5).

4. A method for preparing a dehydrogenation catalyst according to claim 2 or 3, characterized in that: The molecular sieve is selected from ZSM-5 or Beta.

5. The method for preparing a dehydrogenation catalyst according to claim 2, characterized in that: In step 1, the drying temperature is 110-120° C., the drying time is 4-8 hours, the calcination temperature is 500-600° C., and the calcination time is 5-7 hours.

6. A method for preparing a dehydrogenation catalyst according to claim 2, characterized in that: In step 2, the complexing agent is one or a mixture of two or more of sodium tartrate, citric acid or disodium ethylenediaminetetraacetate, and the concentration of the complexing agent is 0.2 mol / L-2.5 mol / L.

7. A method for preparing a novel dehydrogenation catalyst according to claim 2, characterized in that: The metal Pd compound in step 2 is one or a mixture of two or more of palladium chloride, palladium sulfate or palladium nitrate; And / or, the metal Ni compound is one or a mixture of two or more of nickel chloride, nickel sulfate or nickel nitrate; And / or, the metal Mn compound is one or a mixture of two or more of manganese chloride, manganese sulfate or manganese nitrate.

8. The method for preparing a dehydrogenation catalyst according to claim 2, characterized in that: In step 2, the drying temperature is 110-120° C., the drying time is 4-8 hours, the calcination temperature is 500-800° C., and the calcination time is 5-10 hours.

9. Use of the dehydrogenation catalyst as claimed in claim 1 in the synthesis of carvacrol, characterized in that: The following steps are involved: PdNiMn / γ-alumina-molecular sieve dehydrogenation catalyst is added to a tubular reactor, carveol is pumped into the reactor at a uniform speed using a metering pump, and crude carveol flows out after staying for reaction. The crude product can be subjected to simple distillation to obtain finished carveol.

10. Use of the dehydrogenation catalyst according to claim 9 in the synthesis of carvacrol, characterized in that: The loading amount of the dehydrogenation catalyst in the tubular reactor is 600 g / L; And / or, the temperature of the residence reaction is 200-250° C., and the residence time of the residence reaction is 0.5-1 h.

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