A catalyst for the synthesis of limonene-4-ol and its application

Abstract

This invention relates to a catalyst for the synthesis of limonene-4-ol and its application. Specifically, this invention relates to an iron-doped silica-titanium dioxide catalyst, which is prepared by the following method: (1) adding silica to a mixed solvent of ethanol, ethylene glycol monomethyl ether, water, and an organic acid, and stirring to obtain a mixed solution; (2) adding an aqueous solution of ferric nitrate to the mixed solution from step (1), stirring and mixing, then adding n-butyl titanate, reacting, filtering, and drying the resulting filter cake, followed by grinding and calcination to obtain the iron-doped silica-titanium dioxide catalyst. The iron-doped silica-titanium dioxide catalyst of this invention can be applied to the catalytic conversion of isoprene-4,8-epoxide to limonene-4-ol, and effectively improves the yield of limonene-4-ol.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically to a catalyst for the synthesis of limonene-4-ol and its application. Background Technology

[0002] Terpinen-4-ol is a naturally occurring antibacterial agent widely used in the detergent and fragrance industries. It is also an intermediate in pesticide synthesis and is mostly found in Melaleuca alternifolia plants. Due to limited natural resources, the chemical synthesis of terpinen-4-ol will become a significant supplement to the terpinen-4-ol market. Currently, the production process of terpinen-4-ol mainly uses isoterpinene as a raw material, which is epoxidized to obtain isoterpinen-4,8-epoxide, then isomerized to obtain limonene-4-ol, and finally hydrogenated to obtain terpinen-4-ol. The yield of limonene-4-ol from the isomerization of isoterpinen-4,8-epoxide is crucial in the synthesis of terpinen-4-ol and has a significant impact on its production cost, making it a key intermediate in its synthesis. The isomerization of isoterpinene-4,8-epoxide to limonene-4-ol requires a catalyst in the presence of the isomer. However, existing catalysts yield low amounts of limonene-4,8-epoxide for catalytic isomerization. Therefore, improving the yield of limonene-4-ol through catalytic isomerization of isoterpinene-4,8-epoxide has become a hot research topic.

[0003] Therefore, there is a need in the art to develop a method to improve the yield of limonene-4-ol by catalytic isomerization of isoprene-4,8-epoxide. Summary of the Invention

[0004] The purpose of this invention is to provide an iron-doped silica-titanium dioxide catalyst, which can effectively improve the yield of limonene-4,8-epoxide catalytic isomerization to limonene-4-ol.

[0005] The first aspect of this invention provides an iron-doped silica-titanium dioxide catalyst, which is prepared by the following method:

[0006] (1) Add silicon dioxide to a mixed solvent of ethanol, ethylene glycol monomethyl ether, water and organic acid, stir to obtain a mixed solution;

[0007] (2) Add ferric nitrate aqueous solution to the mixed solution in step (1), stir and mix, add titanate n-butyl ester, react and filter, and then dry the filter cake and grind and calcine it in sequence to obtain iron-doped silicon dioxide-titanium dioxide catalyst.

[0008] Preferably, in step (1), the water includes deionized water.

[0009] Preferably, in step (1), the organic acid is selected from the group consisting of formic acid, acetic acid, or a combination thereof.

[0010] Preferably, in step (1), the organic acid includes formic acid.

[0011] Preferably, in step (1), the average particle size of the silicon dioxide is 5-60 nm, more preferably 5-50 nm, more preferably 10-40 nm, more preferably 10-30 nm, more preferably 15-25 nm, more preferably 18-22 nm, and most preferably 20 nm.

[0012] Preferably, in step (1), the mass ratio of ethanol to silicon dioxide is 5-60:1, more preferably 5-50:1, even more preferably 10-40:1, more preferably 10-30:1, more preferably 15-25:1, even more preferably 18-22:1, and most preferably 20:1.

[0013] Preferably, in step (1), the mass ratio of ethylene glycol monomethyl ether to silicon dioxide is 0.03-3:1, more preferably 0.05-1.5:1, even more preferably 0.05-1.0:1, more preferably 0.1-0.8:1, more preferably 0.1-0.5:1, even more preferably 0.2-0.4:1, and most preferably 0.3:1.

[0014] Preferably, in step (1), the mass ratio of water to silicon dioxide is 1-40:1, more preferably 3-30:1, more preferably 5-25:1, more preferably 5-20:1, more preferably 10-15:1, more preferably 12-13:1, and most preferably 12.5:1.

[0015] Preferably, in step (1), the mass ratio of the organic acid to the silicon dioxide is 0.03-3:1, more preferably 0.05-1.5:1, more preferably 0.05-1.0:1, more preferably 0.1-0.8:1, more preferably 0.1-0.5:1, more preferably 0.2-0.4:1, and most preferably 0.3:1.

[0016] Preferably, in step (1), the mass ratio of ethanol, ethylene glycol monomethyl ether, water and organic acid is (190-210):(2.5-3.5):(115-135):(2.5-3.5), more preferably (195-205):(2.8-3.2):(120-130):(2.8-3.2), and even more preferably 200:3:125:3.

[0017] Preferably, in step (1), the stirring time is 0.1-2h, more preferably 0.1-1h, even more preferably 0.3-0.7h, and most preferably 0.5h.

[0018] Preferably, the mass ratio of ferric nitrate in step (2) to silicon dioxide in step (1) is 0.002-0.2:1, more preferably 0.005-0.1:1, even more preferably 0.01-0.05:1, more preferably 0.01-0.03:1, more preferably 0.015-0.025:1, even more preferably 0.018-0.022:1, and most preferably 0.02:1.

[0019] Preferably, in step (2), the weight percentage of ferric nitrate in the ferric nitrate aqueous solution is 10-30%, more preferably 15-25%, more preferably 18-22%, and more preferably 20%.

[0020] Preferably, the mass ratio of the ferric nitrate aqueous solution in step (2) to the silicon dioxide in step (1) is 0.01-1.0:1, more preferably 0.05-0.5:1, more preferably 0.05-0.3:1, more preferably 0.05-0.2:1, more preferably 0.05-0.15:1, more preferably 0.08-0.12:1, and most preferably 0.1:1.

[0021] Preferably, the mass ratio of tetrabutyl titanate in step (2) to silicon dioxide in step (1) is 0.1-10:1, more preferably 0.5-5:1, more preferably 0.5-3:1, more preferably 0.5-2:1, more preferably 0.5-1.5:1, more preferably 0.8-1.2:1, and most preferably 1:1.

[0022] Preferably, in step (2), the stirring time is 0.3-2h, more preferably 0.5-1.5h, even more preferably 0.8-1.2h, and most preferably 1h.

[0023] Preferably, in step (2), tetrabutyl titanate is added at 20-40°C, more preferably 25-35°C, even more preferably 28-32°C, and most preferably 30°C.

[0024] Preferably, in step (2), the reaction temperature is 30-70°C, more preferably 40-60°C, more preferably 45-55°C, even more preferably 48-52°C, and most preferably 50°C.

[0025] Preferably, in step (2), the reaction time is 5-15 hours, more preferably 8-12 hours, and most preferably 10 hours.

[0026] Preferably, in step (2), the obtained filter cake is first washed with water and then dried.

[0027] Preferably, in step (2), the drying temperature is 60-150℃, more preferably 70-130℃, more preferably 80-120℃, even more preferably 90-110℃, and most preferably 100℃.

[0028] Preferably, in step (2), the drying time is 7-9 hours, more preferably 7.5-8.5 hours, and most preferably 8 hours.

[0029] Preferably, in step (2), the calcination temperature is 400-800℃, more preferably 500-700℃, even more preferably 550-650℃, more preferably 580-620℃, even more preferably 590-610℃, and most preferably 600℃.

[0030] Preferably, in step (2), the calcination time is 3-8h, more preferably 4-6h, more preferably 4.5-5.5h, even more preferably 4.8-5.2h, and most preferably 5h.

[0031] In a second aspect, the present invention provides the use of an iron-doped silica-titanium dioxide catalyst as described in the first aspect of the present invention for catalyzing isoprene-4,8-epoxide to limonene-4-ol.

[0032] In a third aspect, the present invention provides a method for preparing limonene-4-ol, the method comprising:

[0033] Iron-doped silica-titanium dioxide catalyst as described in the first aspect of the present invention is added to isoterpinene-4,8-epoxide to react and obtain limonene-4-ol.

[0034] Preferably, the amount of the iron-doped silica-titanium dioxide catalyst is 0.5-15 wt% of isotretinoin-4,8-epoxide, more preferably 1-10 wt%, more preferably 2-8 wt%, more preferably 3-7 wt%, more preferably 4-6 wt%, more preferably 4.5-5.5 wt%, more preferably 4.8-5.2 wt%, and most preferably 5.0 wt%.

[0035] Preferably, the reaction temperature is 120-180°C, more preferably 130-170°C, even more preferably 140-160°C, and most preferably 145-155°C, with the optimal temperature being 150°C.

[0036] Preferably, the reaction time is 5-6 hours, more preferably 5.5-6.5 hours, even more preferably 5.8-6.5 hours, and most preferably 6 hours.

[0037] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Detailed Implementation

[0038] This invention develops an iron-doped silica-titanium dioxide catalyst. The preparation method of the iron-doped silica-titanium dioxide catalyst includes preparing a colloid using silica, n-butyl titanate, and ferric nitrate as raw materials via a sol-gel method. The colloid is then filtered, dried, ground, and calcined to obtain the iron-doped silica-titanium dioxide catalyst. The obtained catalyst can be applied to the isomerization reaction of isoprene-4,8-epoxide to limonene-4-ol, and effectively improves the yield of limonene-4-ol.

[0039] the term

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] As used herein, the terms “comprising,” “including,” and “containing” are used interchangeably and include not only open-ended definitions but also semi-closed and closed definitions. The terms include “consisting of” and “substantially consisting of”.

[0042] As used herein, the term "wt%" refers to a percentage by weight. For example, "20wt% ferric nitrate aqueous solution" means that the weight percentage of ferric nitrate in the ferric nitrate aqueous solution is 20%, and so on.

[0043] As used herein, the structure of the term "ethylene glycol monomethyl ether" is as follows:

[0044]

[0045] As used in this article, the CAS registry number for the term “tetrabutyl titanate” is 5593-70-4.

[0046] As used herein, the structure of the term "isoterpinene-4,8-epoxide" is as follows:

[0047]

[0048] As used in this article, the structure of the term "limonene-4-ol" is as follows:

[0049]

[0050] Iron-doped silica-titanium dioxide catalysts and their applications

[0051] This invention provides an iron-doped silica-titanium dioxide catalyst, which is prepared by the following method:

[0052] (1) Add silicon dioxide to a mixed solvent of ethanol, ethylene glycol monomethyl ether, water and organic acid, stir to obtain a mixed solution;

[0053] (2) Add ferric nitrate aqueous solution to the mixed solution in step (1), stir and mix, add titanate n-butyl ester, react and filter, and then dry the filter cake and grind and calcine it in sequence to obtain iron-doped silicon dioxide-titanium dioxide catalyst.

[0054] The iron-doped silica-titanium dioxide catalyst of the present invention can be used to catalyze the conversion of isoprene-4,8-epoxide to limonene-4-ol.

[0055] Specifically, the iron-doped silicon dioxide-titanium dioxide catalyst of the present invention is as described in the first aspect of the present invention above.

[0056] The main technical effects of this invention include:

[0057] This invention develops an iron-doped silica-titanium dioxide catalyst. The preparation method of the iron-doped silica-titanium dioxide catalyst includes preparing the iron-doped silica-titanium dioxide catalyst in a one-pot process using silica, tetrabutyl titanate and ferric nitrate as raw materials.

[0058] The method for preparing the iron-doped silica-titanium dioxide catalyst described in this invention is simple, produces little waste, and can be applied to the isomerization reaction of isoprene-4,8-epoxide to limonene-4-ol, effectively improving the yield of limonene-4-ol. It can be recycled and reused multiple times, has low cost, produces little waste, and is beneficial for industrial production.

[0059] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0060] Example

[0061] The structure of ethylene glycol monomethyl ether is as follows:

[0062]

[0063] The CAS Registry Number for tetrabutyl titanate is 5593-70-4.

[0064] The structure of isoprene-4,8-epoxide is as follows:

[0065]

[0066] The structure of limonene-4-ol is as follows:

[0067]

[0068] Example 1

[0069] This Example 1 provides a method for preparing limonene-4-ol, which is prepared by the following method:

[0070] (1) Add 20.0g of silica with an average particle size of 20nm to a mixed solvent of 400.0g ethanol, 6.0g ethylene glycol monomethyl ether, 250.0g deionized water and 6.0g formic acid, and stir for 0.5h to obtain a mixed solution.

[0071] (2) Add 2.0g of 20wt% ferric nitrate aqueous solution to the mixed solution in step (1), stir for 1h, add 20.0g of tetrabutyl titanate at 30℃, react at 50℃ for 10.0h, filter, wash once with deionized water, dry the filter cake at 100℃ for 8h, grind, calcine at 600℃ for 5.0h to obtain iron-doped silicon dioxide-titanium dioxide catalyst.

[0072] (3) The iron-doped silica-titanium dioxide catalyst prepared in step (2) was added to isotretinoin-4,8-epoxide (wherein, the amount of iron-doped silica-titanium dioxide catalyst was 5 wt% of the amount of isotretinoin-4,8-epoxide), and reacted at 150 °C for 6 h to obtain limonene-4-ol. The yield of limonene-4-ol was measured to be 73.1%. The catalyst was reused (reuse refers to the recovery of the iron-doped silica-titanium dioxide catalyst for use in the next batch of reaction, which can be reused repeatedly) 20 times, with an average yield of 72.3%.

[0073] Comparative Example 1

[0074] Comparative Example 1 provides a method for preparing limonene-4-ol, which is prepared by the following method:

[0075] (1) Add 20.0g of silica with an average particle size of 20nm to a mixed solvent of 600.0g of ethanol and 8.0g of formic acid, and stir for 0.5h to obtain a mixed solution.

[0076] (2) Add 2.0g of 20wt% ferric nitrate aqueous solution to the mixed solution in step (1), stir for 1h, add 30.1g of tetrabutyl titanate at 30℃, react at 30℃ for 10.0h, filter, wash once with deionized water, dry the filter cake at 100℃ for 8h, grind, calcine at 600℃ for 5.0h to obtain iron-doped silicon dioxide-titanium dioxide catalyst.

[0077] (3) The iron-doped silica-titanium dioxide catalyst prepared in step (2) was added to isoterpinene-4,8-epoxide (wherein, the amount of iron-doped silica-titanium dioxide catalyst was 5 wt% of the amount of isoterpinene-4,8-epoxide), and the reaction was carried out at 150 °C for 6 h to obtain limonene-4-ol. The yield of limonene-4-ol was 63.8%.

[0078] Comparative Example 2

[0079] Comparative Example 2 provides a method for preparing limonene-4-ol, which is prepared by the following method:

[0080] (1) Add 20.0g of silica with an average particle size of 20nm to a mixed solvent of 4.0g of ethylene glycol monomethyl ether and 12.0g of acetic acid, and stir for 0.5h to obtain a mixed solution.

[0081] (2) Add 3.1g of 20wt% ferric nitrate aqueous solution to the mixed solution in step (1), stir for 1h, add 36.5g of tetrabutyl titanate at 30℃, react at 50℃ for 10.0h, filter, wash once with deionized water, dry the filter cake at 100℃ for 8h, grind, calcine at 750℃ for 4.0h to obtain iron-doped silicon dioxide-titanium dioxide catalyst.

[0082] (3) The iron-doped silica-titanium dioxide catalyst prepared in step (2) was added to isoterpinene-4,8-epoxide (wherein, the amount of iron-doped silica-titanium dioxide catalyst was 5 wt% of the amount of isoterpinene-4,8-epoxide), and the reaction was carried out at 150 °C for 6 h to obtain limonene-4-ol. The yield of limonene-4-ol was 65.2%.

[0083] Comparative Example 3

[0084] Comparative Example 3 provides a method for preparing limonene-4-ol, which is prepared by the following method:

[0085] (1) Add 20.0g of silica with an average particle size of 40nm to a mixed solvent of 16.0g of ethylene glycol monomethyl ether and 16.0g of formic acid, and stir for 0.5h to obtain a mixed solution.

[0086] (2) Add 5.0g of 20wt% ferric nitrate aqueous solution to the mixed solution in step (1), stir for 1h, add 20.0g of tetrabutyl titanate at 30℃, react at 50℃ for 10.0h, filter, wash once with deionized water, dry the filter cake at 100℃ for 8h, grind, calcine at 550℃ for 8.0h to obtain iron-doped silicon dioxide-titanium dioxide catalyst.

[0087] (3) The iron-doped silica-titanium dioxide catalyst prepared in step (2) was added to isoterpinene-4,8-epoxide (wherein, the amount of iron-doped silica-titanium dioxide catalyst was 5 wt% of the amount of isoterpinene-4,8-epoxide), and the reaction was carried out at 150 °C for 6 h to obtain limonene-4-ol. The yield of limonene-4-ol was 62.5%.

[0088] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. The use of an iron-doped silica-titanium dioxide catalyst, characterized in that, The iron-doped silica-titanium dioxide catalyst is used to catalyze the conversion of isoprene-4,8-epoxide to limonene-4-ol. The iron-doped silica-titanium dioxide catalyst is prepared by the following method: (1) Add silicon dioxide to a mixed solvent of ethanol, ethylene glycol monomethyl ether, water and organic acid, stir to obtain a mixed solution; (2) Add ferric nitrate aqueous solution to the mixed solution in step (1), stir and mix, add titanate n-butyl ester, react and filter, and then dry the filter cake and grind and calcine it in sequence to obtain iron-doped silicon dioxide-titanium dioxide catalyst.

2. The use of the iron-doped silica-titanium dioxide catalyst as described in claim 1, characterized in that, In step (1), the organic acid is selected from the group consisting of formic acid, acetic acid, or a combination thereof.

3. The use of the iron-doped silica-titanium dioxide catalyst as described in claim 1, characterized in that, The average particle size of the silica is 5-60 nm.

4. The use of the iron-doped silica-titanium dioxide catalyst as described in claim 1, characterized in that, In step (1), the mass ratio of ethanol, ethylene glycol monomethyl ether, water and organic acid is (190-210):(2.5-3.5):(115-135):(2.5-3.5).

5. The use of the iron-doped silica-titanium dioxide catalyst as described in claim 1, characterized in that, The mass ratio of ferric nitrate in step (2) to silicon dioxide in step (1) is 0.002-0.2:1; and / or The mass ratio of tetrabutyl titanate in step (2) to silicon dioxide in step (1) is 0.1-10:

1.

6. The use of the iron-doped silica-titanium dioxide catalyst as described in claim 1, characterized in that, In step (2), the reaction temperature is 30-70°C; and / or In step (2), the reaction time is 5-15 hours.

7. The use of the iron-doped silica-titanium dioxide catalyst as described in claim 1, characterized in that, In step (2), the calcination temperature is 400-800℃; and / or In step (2), the calcination time is 3-8 hours.

8. The use of the iron-doped silica-titanium dioxide catalyst as described in claim 1, characterized in that, The amount of the iron-doped silica-titanium dioxide catalyst is 0.5-15 wt% of isoprene-4,8-epoxide.

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