A process for the preparation of methyl anisole

Abstract

The present application relates to a kind of phenol and methanol directly prepared (methyl) anisole mode, the method includes the following steps: under the action of composite catalyst, phenol and methanol are catalytically generated methyl anisole, the composite catalyst is Ho / β molecular sieve catalyst and Ti / UiO-66 with mass ratio Ho / β:Ti / UiO-66 0.3-0.6:1 Mixed composite catalyst.The process reaction step is simple, and synthesis is realized in one step, and the total selectivity of methyl anisole is as high as 76% or more, and can be continuously and stably operated for 3000h.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis, specifically to a process for preparing (methyl)anisole by reacting phenol with methanol. Background Technology

[0002] (Methyl)anisole is an important class of chemical intermediates, including anisole, o-methylanisole, m-methylanisole, and p-methylanisole. Among them, o-methylanisole is an organic synthesis intermediate used in the pesticide industry to manufacture herbicides such as NK-409; m-methylanisole is a fragrance and flavor intermediate and a raw material for pressure-sensitive and heat-sensitive dyes; p-methylanisole is a natural fragrance that can be used to formulate various floral fragrances and nutty flavorings for food.

[0003] Currently, the synthesis of methyl anisole primarily involves the reaction of cresol (o-cresol, m-cresol, and p-cresol) with methylating agents. Patent CN109277115A uses a molecular sieve catalyst to react o-cresol with methanol to obtain o-methyl anisole. Patent CN111072459B uses m-cresol and dimethyl sulfate in a cyclic reaction to obtain m-methyl anisole. Patent CN113509947B provides a method for synthesizing p-methyl anisole, using p-cresol and dimethyl carbonate in a composite system of a main catalyst and antioxidant. However, these methods suffer from the high price of cresol, resulting in high costs for the prepared methyl anisole. Developing a simple, efficient, low-cost, and safe process is a crucial area for future research. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing methyl anisole, employing a novel catalyst to catalyze the reaction of phenol and methanol to produce methyl anisole in a one-step process. This process uses phenol, which is cheaper, as a raw material, significantly reducing costs compared to cresol. Furthermore, using methanol as a raw material is cheaper than using dimethyl carbonate and dimethyl sulfate, which are commonly used in industry. The continuous fixed-bed process results in high reaction efficiency, eliminates the need for other solvents, and reduces separation costs. In addition, the reaction steps are simple, achieving synthesis in one step, exhibiting good reactivity and selectivity, and enabling long-term stable operation, making it an ideal process for industrial production.

[0005] On one hand, the present invention provides a method for preparing methyl anisole, the method comprising: catalytically generating methyl anisole from phenol and methanol under the action of a composite catalyst.

[0006] Preferably, the reaction of phenol and methanol is carried out in a continuous fixed-bed reaction.

[0007] Preferably, the amount of phenol added is 0.1-0.7% of the total mass of phenol and methanol.

[0008] Preferably, the reaction temperature of phenol and methanol is 240-360℃, the reaction pressure is 0.5-4.5 bar (A), and the liquid hourly space velocity (LHSV) of phenol is 0.05-0.6 h⁻¹. -1 .

[0009] Preferably, the composite catalyst is a composite catalyst in which Ho / β molecular sieve catalyst and Ti / UiO-66 are mixed in a certain proportion; preferably, in the composite catalyst, the mass ratio of Ho / β:Ti / UiO-66 is 0.3-0.6:1, and the two catalysts are physically mixed.

[0010] In this invention, the preparation process of the Ho / β molecular sieve includes the following steps:

[0011] (1) Dissolve the holmium source in distilled water to obtain an aqueous solution of the holmium source;

[0012] (2) The β molecular sieve was dissolved in an aqueous solution of holmium source and impregnated;

[0013] (3) The impregnated sample was dried and calcined to obtain the Ho / β molecular sieve catalyst.

[0014] Preferably, in step (1), the holmium source is one or more of holmium chloride, holmium acetylacetonate, holmium acetate hydrate, and holmium nitrate pentahydrate, and the mass of the holmium source is 0.1-0.6 times the mass of water;

[0015] Preferably, the β molecular sieve in step (2) is one or more of NKF-6-25H, NKF-6-30H, NKF-6-40H, NKF-6-60H and NKF-6-100H sold by Tianjin Nanhua Catalyst Co., Ltd.

[0016] Preferably, the mass of the holmium source in step (2) is 0.2-0.8 times that of the β molecular sieve; the impregnation is carried out at room temperature for 12-48 hours.

[0017] Preferably, the drying temperature in step (3) is 100-110℃ and the drying time is 5-12h;

[0018] Preferably, in step (3), the roasting is carried out at 400-650℃ for 4-12 hours.

[0019] In this invention, the preparation process of Ti / UiO-66 includes the following steps:

[0020] (1) Dissolve a certain amount of zirconium source, titanium source and solvent A in solvent B;

[0021] (2) Place the dissolved solution into the reactor for reaction;

[0022] (3) After the reaction is complete, wash with solvent B and centrifuge;

[0023] (4) Dry the centrifuged sample to obtain the Ti / UiO-66 catalyst.

[0024] Preferably, in step (1), the zirconium source is one or more of zirconium chloride, zirconium fluoride and zirconium acetylacetonate, the titanium source is one or more of titanium tetrachloride, tetrabutyl titanate and titanium tetrafluoride, solvent A is one or more of phthalic acid, isophthalic acid and terephthalic acid, and solvent B is one or more of N,N-dimethylformamide and N,N-dimethylacetamide.

[0025] Preferably, in step (1), the mass of solvent B is 50-150 times the mass of the zirconium source;

[0026] Preferably, in step (1), the mass of the titanium source is 0.02-0.2 times the mass of the zirconium source;

[0027] Preferably, in step (1), the mass of solvent A is 0.5-1.5 times the mass of the zirconium source;

[0028] Preferably, the reaction temperature in step (2) is 60-140℃ and the reaction time is 3-48h;

[0029] Preferably, the drying temperature in step (4) is 60-120℃ and the drying time is 6-24h.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. This invention provides a novel synthetic process for methyl anisole;

[0032] 2. This invention develops a highly efficient catalyst using a continuous fixed-bed process, achieving a selectivity of over 76% for methyl anisole and stable operation for 3000 hours. The Ti / UiO-66 catalyst provides suitable acidity and basicity, promoting the adsorption of phenol and methanol. Ho, confined within the β-zeolite, forms highly active catalytic centers, further promoting the reaction of phenol and methanol. Detailed Implementation

[0033] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention.

[0034] The present invention will be further described below with reference to embodiments, but these embodiments do not constitute any limitation.

[0035] The reactor used in the example: The reaction is carried out in a fixed-bed reactor made of 316L material, the inner diameter of the reaction tube is 20mm, and the catalyst is filled with 316L distillation packing at both ends.

[0036] The composition of the m-methylphenol-ethanol reaction solution was analyzed by gas chromatography. The operating conditions were as follows: a Shimadzu GC-2030 gas chromatograph with a GL C18-H 5µm 4.6 x 50 mm column and N,N-dimethylformamide as the diluent; vaporization chamber temperature 320℃; column flow rate 0.800 mL / min; and injection volume 0.3 μL. The column temperature program was as follows: first, the temperature was increased from 40℃ to 160℃ at a rate of 3℃ / min, and finally increased to 270℃ at a rate of 5℃ / min.

[0037] The raw materials used in the examples are shown in Table 1.

[0038] Table 1 Source of Raw Materials

[0039]

[0040] Example 1:

[0041] The catalyst is prepared as follows:

[0042] The catalyst is a composite catalyst consisting of Ho / β molecular sieve and Ti / UiO-66 mixed in a certain proportion; wherein the mass of Ho / β is 0.6 times the mass of Ti / UiO-66, and the two catalysts are mixed uniformly.

[0043] The preparation process of Ho / β molecular sieve includes the following steps:

[0044] (1) Dissolve 100g of holmium chloride in distilled water, with the mass of the holmium source being 0.3 times the mass of the distilled water, to obtain an aqueous solution of holmium chloride;

[0045] (2) Dissolve β molecular sieve (NKF-6-25H) in an aqueous solution of holmium chloride and soak it at room temperature for 24 hours, wherein the mass of holmium chloride is 0.4 times that of β molecular sieve;

[0046] (3) Dry the impregnated sample at 110℃ for 12h;

[0047] (4) The dried sample was calcined at 450°C for 5 hours in an air atmosphere to obtain the Ho / β molecular sieve catalyst.

[0048] The preparation process of Ti / UiO-66 includes the following steps:

[0049] (1) Dissolve zirconium acetylacetonate (100g), titanium tetrachloride and isophthalic acid in N,N-dimethylformamide solution, wherein the mass of N,N-dimethylformamide is 65 times the mass of zirconium acetylacetonate, the mass of titanium tetrachloride is 0.18 times the mass of zirconium acetylacetonate, and the mass of isophthalic acid is 1.2 times the mass of zirconium acetylacetonate.

[0050] (2) Place the dissolved solution into a polytetrafluoroethylene high-pressure reactor and react at 70°C for 5 hours;

[0051] (3) After the reaction was completed, wash with N,N-dimethylformamide and centrifuge three times;

[0052] (4) The centrifuged sample was dried at 100℃ for 10h to obtain the Ti / / UiO-66 catalyst;

[0053] The reaction conditions for phenol and methanol are as follows:

[0054] The reaction of phenol and methanol was carried out in a continuous fixed-bed reaction. The amount of phenol added was 0.4% of the total mass of phenol and methanol. The reaction temperature of phenol and methanol was 260℃, the reaction pressure was 2.3 bar (A), and the liquid hourly space velocity (LHSV) of phenol was 0.5 h⁻¹. -1 After the reaction stabilized, samples were taken and analyzed by gas chromatography. Specific results for the examples are shown in Table 1.

[0055] Example 2:

[0056] The catalyst is prepared as follows:

[0057] The catalyst is a composite catalyst consisting of Ho / β molecular sieve and Ti / UiO-66 mixed in a certain proportion; wherein the mass of Ho / β is 0.4 times the mass of Ti / UiO-66, and the two catalysts are mixed uniformly.

[0058] The preparation process of Ho / β molecular sieve includes the following steps:

[0059] (1) Dissolve 100g of holmium acetate hydrate in distilled water, with the mass of the holmium source being 0.4 times the mass of the distilled water, to obtain an aqueous solution of holmium acetate hydrate;

[0060] (2) Dissolve β molecular sieve (NKF-6-40H) in an aqueous solution of holmium acetate and soak it at room temperature for 24 hours, wherein the mass of holmium acetate hydrate is 0.8 times that of β molecular sieve;

[0061] (3) Dry the impregnated sample at 110℃ for 12h;

[0062] (4) The dried sample was calcined at 600℃ for 11h in air atmosphere to obtain Ho / β molecular sieve catalyst.

[0063] The preparation process of Ti / UiO-66 includes the following steps:

[0064] (1) Dissolve zirconium chloride (100g), tetrabutyl titanate and terephthalic acid in N,N-dimethylacetamide solution, wherein the mass of N,N-dimethylacetamide is 78 times the mass of zirconium chloride, the mass of titanium tetrachloride is 0.11 times the mass of zirconium chloride, and the mass of terephthalic acid is 1.0 times the mass of zirconium chloride.

[0065] (2) Place the dissolved solution into a polytetrafluoroethylene high-pressure reactor and react at 120°C for 15 hours;

[0066] (3) After the reaction was completed, wash with N,N-dimethylacetamide and centrifuge three times;

[0067] (4) The centrifuged sample was dried at 110℃ for 6h to obtain the Ti / / UiO-66 catalyst;

[0068] The reaction conditions for phenol and methanol are as follows:

[0069] The reaction of phenol and methanol was carried out in a continuous fixed-bed reaction. The amount of phenol added was 0.5% of the total mass of phenol and methanol. The reaction temperature of phenol and methanol was 280℃, the reaction pressure was 1.2 bar (A), and the liquid hourly space velocity (LHSV) of phenol was 0.4 h⁻¹. -1 After the reaction stabilized, samples were taken and analyzed by gas chromatography. Specific results for the examples are shown in Table 1.

[0070] Example 3:

[0071] The catalyst is prepared as follows:

[0072] The catalyst is a composite catalyst consisting of Ho / β molecular sieve and Ti / UiO-66 mixed in a certain proportion; wherein the mass of Ho / β is 0.3 times the mass of Ti / UiO-66, and the two catalysts are mixed uniformly.

[0073] The preparation process of Ho / β molecular sieve includes the following steps:

[0074] (1) Dissolve 100g of holmium acetylacetonate in distilled water, with the mass of the holmium source being 0.2 times the mass of the distilled water, to obtain an aqueous solution of holmium acetylacetonate;

[0075] (2) Dissolve β molecular sieve (NKF-6-30H) in an aqueous solution of holmium acetylacetonate and soak it at room temperature for 24 hours, wherein the mass of holmium acetylacetonate is 0.6 times that of β molecular sieve;

[0076] (3) Dry the impregnated sample at 110℃ for 12h;

[0077] (4) The dried sample was calcined at 550°C for 7 h in an air atmosphere to obtain the Ho / β molecular sieve catalyst.

[0078] The preparation process of Ti / UiO-66 includes the following steps:

[0079] (1) Dissolve zirconium fluoride (100g), tetrabutyl titanate and phthalic acid in N,N-dimethylformamide solution, wherein the mass of N,N-dimethylformamide is 129 times the mass of zirconium fluoride, the mass of tetrabutyl titanate is 0.04 times the mass of zirconium fluoride, and the mass of phthalic acid is 0.6 times the mass of zirconium fluoride.

[0080] (2) Place the dissolved solution into a polytetrafluoroethylene high-pressure reactor and react at 80°C for 43 hours;

[0081] (3) After the reaction was completed, wash with N,N-dimethylformamide and centrifuge three times;

[0082] (4) The centrifuged sample was dried at 80℃ for 20h to obtain the Ti / / UiO-66 catalyst;

[0083] The reaction conditions for phenol and methanol are as follows:

[0084] The reaction of phenol and methanol was carried out in a continuous fixed-bed reaction. The amount of phenol added was 0.3% of the total mass of phenol and methanol. The reaction temperature of phenol and methanol was 340℃, the reaction pressure was 0.7 bar (A), and the liquid hourly space velocity (LHSV) of phenol was 0.15 h⁻¹. -1 After the reaction stabilized, samples were taken and analyzed by gas chromatography. Specific results for the examples are shown in Table 1.

[0085] Example 4:

[0086] The catalyst is prepared as follows:

[0087] The catalyst is a composite catalyst consisting of Ho / β molecular sieve and Ti / UiO-66 mixed in a certain proportion; wherein the mass of Ho / β is 0.5 times the mass of Ti / UiO-66, and the two catalysts are mixed uniformly.

[0088] The preparation process of Ho / β molecular sieve includes the following steps:

[0089] (1) Dissolve 100g of holmium nitrate in distilled water, with the mass of the holmium source being 0.6 times the mass of the distilled water, to obtain an aqueous solution of holmium nitrate;

[0090] (2) Dissolve β molecular sieve (NKF-6-100H) in an aqueous solution of holmium nitrate and soak it at room temperature for 24 hours, wherein the mass of holmium nitrate is 0.3 times that of β molecular sieve;

[0091] (3) Dry the impregnated sample at 110℃ for 12h;

[0092] (4) The dried sample was calcined at 500℃ for 10h in an air atmosphere to obtain the Ho / β molecular sieve catalyst.

[0093] The preparation process of Ti / UiO-66 includes the following steps:

[0094] (1) Dissolve zirconium acetylacetonate (100g), titanium tetrachloride and isophthalic acid in N,N-dimethylacetamide solution, wherein the mass of N,N-dimethylformamide is 104 times the mass of zirconium acetylacetonate, the mass of titanium tetrachloride is 0.07 times the mass of zirconium acetylacetonate, and the mass of isophthalic acid is 0.9 times the mass of zirconium acetylacetonate.

[0095] (2) Place the dissolved solution into a polytetrafluoroethylene high-pressure reactor and react at 110°C for 29 hours;

[0096] (3) After the reaction was completed, wash with N,N-dimethylacetamide and centrifuge three times;

[0097] (4) The centrifuged sample was dried at 90℃ for 15h to obtain the Ti / / UiO-66 catalyst;

[0098] The reaction conditions for phenol and methanol are as follows:

[0099] The reaction of phenol and methanol was carried out in a continuous fixed-bed reaction. The amount of phenol added was 0.2% of the total mass of phenol and methanol. The reaction temperature of phenol and methanol was 300℃, the reaction pressure was 3.8 bar (A), and the liquid hourly space velocity (LHSV) of phenol was 2.5 h⁻¹. -1 After the reaction stabilized, samples were taken and analyzed by gas chromatography. Specific results for the examples are shown in Table 1.

[0100] The catalyst prepared in Example 2 was used for a lifetime test. The specific reaction steps were the same as in Example 2. After running for 3000 hours, the conversion rate was 41% and the selectivity was 76%, with no significant decrease in activity and selectivity.

[0101] Comparative Example 1:

[0102] The catalyst preparation method was basically the same as in Example 1, the only difference being the absence of the Ti / UiO-66 catalyst. The reaction conditions for phenol and methanol were the same as in Example 1.

[0103] Comparative Example 2:

[0104] The catalyst was prepared using a method essentially the same as in Example 1, the only difference being the absence of the Ho / β molecular sieve. The reaction conditions for phenol and methanol were the same as in Example 1.

[0105] Table 2 Conversion rates and selectivity of each embodiment

[0106]

[0107]

[0108] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for preparing methyl anisole, characterized in that, The method comprises: catalyzing phenol and methanol to produce methyl anisole under the action of a composite catalyst, wherein the composite catalyst is a mixture of Ho / β molecular sieve catalyst and Ti / UiO-66 in a mass ratio of Ho / β:Ti / UiO-66 of 0.3-0.6:

1.

2. The preparation method according to claim 1, characterized in that, The amount of phenol added is 0.1-0.7% of the total mass of phenol and methanol.

3. The preparation method according to claim 1, characterized in that, The reaction temperature of phenol and methanol is 240-360℃, the reaction pressure is 0.5-4.5 bar (A), and the liquid hourly space velocity (LHSV) of phenol is 0.05-0.6 h⁻¹. -1 .

4. The preparation method according to any one of claims 1-3, characterized in that, The preparation process of the Ho / β molecular sieve includes the following steps: (1) Dissolve the holmium source in distilled water to obtain an aqueous solution of the holmium source; (2) The β molecular sieve was dissolved in an aqueous solution of holmium source and impregnated; (3) The impregnated sample was dried and calcined to obtain the Ho / β molecular sieve catalyst.

5. The preparation method according to claim 4, characterized in that, In step (1), the holmium source is one or more of holmium chloride, holmium acetylacetonate, holmium acetate hydrate, and holmium nitrate pentahydrate, and the mass of the holmium source is 0.1-0.6 times the mass of water; and / or, in step (2), the β molecular sieve is one or more of NKF-6-25H, NKF-6-30H, NKF-6-40H, NKF-6-60H, and NKF-6-100H from Tianjin Nanhua Catalyst Co., Ltd.

6. The preparation method according to claim 4, characterized in that, In step (2), the mass of the holmium source is 0.2-0.8 times that of the β molecular sieve; the impregnation is carried out at room temperature for 12-48 hours; and / or, in step (3), the drying temperature is 100-110°C and the drying time is 5-12 hours; and / or, in step (3), the calcination is carried out at 400-650°C for 4-12 hours.

7. The preparation method according to any one of claims 1-3, characterized in that, The preparation process of Ti / UiO-66 includes the following steps: (1) Dissolve a certain amount of zirconium source, titanium source and solvent A in solvent B; (2) Place the dissolved solution into the reactor for reaction; (3) After the reaction is complete, wash with solvent B and centrifuge; (4) Dry the centrifuged sample to obtain the Ti / UiO-66 catalyst.

8. The preparation method according to claim 7, characterized in that, In step (1), the zirconium source is one or more of zirconium chloride, zirconium fluoride and zirconium acetylacetonate, the titanium source is one or more of titanium tetrachloride, tetrabutyl titanate and titanium tetrafluoride, solvent A is one or more of phthalic acid, isophthalic acid and terephthalic acid, and solvent B is one or more of N,N-dimethylformamide and N,N-dimethylacetamide.

9. The preparation method according to claim 7, characterized in that, In step (1), the mass of solvent B is 50-150 times the mass of zirconium source; and / or, in step (1), the mass of titanium source is 0.02-0.2 times the mass of zirconium source; and / or, in step (1), the mass of solvent A is 0.5-1.5 times the mass of zirconium source.

10. The preparation method according to claim 7, characterized in that, The reaction temperature in step (2) is 60-140℃ and the reaction time is 3-48h; and / or, the drying temperature in step (4) is 60-120℃ and the drying time is 6-24h.

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