A supported solid base catalyst, its preparation method and application

Abstract

The application provides a supported solid base catalyst, which comprises a carrier, an active component and a regulator, the active component and the regulator are loaded on the carrier, the active component is an alkali metal compound or an alkaline earth metal compound, the regulator is a rare earth metal compound, and the carrier is a metal oxide or a molecular sieve with a large pore structure; the application also provides a preparation method and application of the supported solid base catalyst; the active component mixed with the regulator is loaded on the carrier to obtain a precursor, and after high-temperature calcination, the precursor reacts with the carrier to form an active center, thereby preparing the supported solid base catalyst with excellent catalytic activity, which is used for catalyzing condensation reaction of 6-methyl-5-heptene-2-ketone and acetonitrile to generate citral; and the application solves the technical problems of low raw material utilization, low product yield, complicated post-treatment process and high production cost in the existing citral preparation method, and can be widely applied to the technical field of organic synthesis.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic synthesis, in particular to a supported solid base catalyst and its preparation method and application. BACKGROUND

[0002] Citral nitrile, scientific name 3,7-dimethyl-2,6-octadiene-1-nitrile, also known as orange flower nitrile and geranil nitrile, has a fresh lemon fragrance and can be used to prepare floral and fruity fragrances. In addition, selective reduction of the double bond conjugated with the cyano group in the citral nitrile molecule can produce citronellyl nitrile, which has a fresh lemon fragrance and a clear tea fragrance and is a high-quality spice for modulating citrus flavors. Therefore, it is of great significance to study the preparation method of citral nitrile.

[0003] Currently, citral nitrile is generally prepared from citral and hydroxylamine as raw materials through condensation reaction to obtain citral oxime, which is then dehydrated to obtain citral nitrile; or citral is gasified and then ammoniated in the presence of a catalyst to obtain citral nitrile, or citral is first subjected to amination reaction with ammonia water in the presence of a catalyst, and then subjected to oxidation reaction with an oxidizing agent to obtain citral nitrile. Both methods use citral as raw material, which is expensive, resulting in high production cost. In addition, the preparation process of these two methods is complex and the reaction route is long.

[0004] Based on the above situation, Alain Valla et al. used 6-methyl-5-heptene-2-ketone and acetonitrile as starting materials to generate citral nitrile under the catalysis of KOH solid. This method has a simple preparation process, but in the presence of strong base, the starting material 6-methyl-5-heptene-2-ketone is unstable and prone to self-condensation reaction, resulting in low utilization rate of raw materials and low yield of product. The yield of product is only 65%, and the self-condensation of raw materials generates a large amount of by-products, making it difficult to separate the reaction product and complicating the post-treatment process, greatly increasing the production cost and energy consumption. In addition, the amount of KOH solid catalyst used is large, accounting for 50% of the amount of 6-methyl-5-heptene-2-ketone, which also leads to high production cost.

[0005] Therefore, there is an urgent need to develop a catalyst with high catalytic activity to replace KOH solid catalyst to improve the utilization rate of raw materials and the yield of product, simplify the post-treatment process and reduce the production cost. SUMMARY

[0006] To solve the above technical problems, the technical solution adopted by the present application is to provide a supported solid base catalyst and its preparation method and application, to solve the technical problems of low utilization rate of raw materials, low yield of product, complicated post-treatment process and high production cost existing in the current preparation method of citral nitrile.

[0007] The first aspect of the embodiment of the present application provides a supported solid base catalyst, comprising a carrier, an active component and a regulator, the active component and the regulator being supported on the carrier, the active component being an alkali metal compound or an alkaline earth metal compound, the regulator being a rare earth metal compound, and the carrier being a metal oxide or a molecular sieve with a large pore structure.

[0008] Preferably, the rare earth metal compound is a lanthanum compound, and the lanthanum compound is any one or a combination of at least two of lanthanum oxide, lanthanum chloride, lanthanum carbonate, lanthanum acetate, lanthanum nitrate, lanthanum hydroxide and a hydrate thereof.

[0009] Preferably, the alkali metal compound and the alkaline earth metal compound are any one or a combination of at least two of acid salts, oxides, hydroxides and hydrates of Li, Na, K, Ca, Ba, Mg and Cs, and the metal oxide and the molecular sieve with a large pore structure are any one or a combination of at least two of ZrO2, SiO2, Al2O3, SBA-15 and Al-MCM-41.

[0010] The acid salts of Li, Na, K, Ca, Ba, Mg and Cs can be fluorides, chlorides, acetates, carbonates, bicarbonates and nitrates, and the alkali metal compound and the alkaline earth metal compound are water-soluble.

[0011] The second aspect of the embodiment of the present application provides a preparation method of the supported solid base catalyst described in any one of the above, comprising the following steps.

[0012] The active component is mixed with ammonia water to form an aqueous solution, then the regulator is added, stirred until completely dissolved, and then the carrier is added, and loading is performed by stirring and heating. After loading is completed, filtration and drying are performed to obtain a precursor, and the precursor is calcined to obtain the supported solid base catalyst.

[0013] Preferably, the mass fraction of the active component in the aqueous solution is 0.1-2%, the mass ratio of the active component to the regulator is 1:0.001-1:0.5, and the mass ratio of the active component to the carrier is 1:20-1:100.

[0014] Preferably, the heating temperature during loading is 40-80℃, and the holding time is 2-8h; the calcination temperature is 300-1000℃, and the calcination time is 2-12h.

[0015] The third aspect of the embodiment of the present application provides an application of the supported solid base catalyst described in any one of the above in preparation of citral nitrile, comprising the following steps.

[0016] Mixing 6-methyl-5-hepten-2-one, acetonitrile and the supported solid base catalyst, stirring, heating and holding for condensation reaction, after the reaction, filtering, and the filtrate is subjected to rectification to obtain citral.

[0017] Preferably, the condensation reaction does not need a solvent.

[0018] Preferably, a solvent is added before the condensation reaction, the solvent is any one of toluene, xylene, trimethylbenzene, cyclohexane, ethanol, n-propanol, isopropanol, n-butanol and cyclohexanol, and the mass ratio of 6-methyl-5-hepten-2-one to the solvent is 1:0.1-1:6.

[0019] Preferably, the molar ratio of 6-methyl-5-hepten-2-one to acetonitrile is 1:0.5-1:5, the mass ratio of 6-methyl-5-hepten-2-one to the supported solid base catalyst is 1:0.01-1:0.4, and the reaction temperature of the condensation reaction is 35-125℃, and the reaction time is 1-22h.

[0020] The application provides a supported solid base catalyst and a preparation method thereof, wherein an alkali metal compound or an alkali earth metal compound is used as an active component, a rare earth metal lanthanum compound is used as an adjusting agent, and a metal oxide or a molecular sieve with a large pore structure is used as a carrier, the active component mixed with the adjusting agent is loaded on the carrier to obtain a precursor, and the precursor is subjected to high-temperature calcination to form an active center in cooperation with the carrier, so that the supported solid base catalyst with excellent catalytic activity is prepared. The metal ions can exist in two ways on the carrier: one is that the metal ions are ion-exchanged with the carrier to become a part of the carrier lattice, and the other is that the metal ions are directly dispersed on the carrier in the form of metal or compound. The metal oxide or the molecular sieve with a large pore structure is used as a skeleton of the active component, plays a role of dispersing the active component and increasing the strength of the catalyst, and in addition, the carrier can increase the specific surface area and pore volume of the catalyst and improve the activity of the catalyst; the rare earth metal lanthanum compound is used as the adjusting agent and has the effects of improving the activity of the catalyst and the selectivity to the target product.

[0021] The application also provides application of the supported solid base catalyst in preparation of citral. In the reaction of preparing citral, the supported solid base catalyst forms a carbon negative ion through an electron collection ligand, so that the reaction occurs, that is, the active center of the supported solid base catalyst combines with hydrogen on the methyl in acetonitrile to occur polar decomposition, removes one H + from the acetonitrile to form a carbon negative ion, the carbon negative ion attacks a carbonyl carbon in 6-methyl-5-hepten-2-one to form an intermediate alcohol negative ion, the intermediate alcohol negative ion combines with a hydrogen ion to form an alcohol, and the alcohol hydroxyl group and the H in the alpha position of the alcohol hydroxyl group occur dehydration reaction to form a double bond, that is, citral is generated, and the reaction mechanism is as follows:

[0022]

[0023] Compared with the prior art, the application has the advantages that:

[0024] (1) The application uses a supported solid base as a catalyst to catalyze the condensation reaction of 6-methyl-5-heptene-2-ketone and acetonitrile to generate citral, thereby inhibiting the occurrence of the self-condensation reaction of 6-methyl-5-heptene-2-ketone, improving the utilization rate of raw materials and the yield of products, eliminating or reducing the generation of by-products, simplifying the post-processing process, reducing production costs, and being environmentally friendly.

[0025] (2) The supported solid base catalyst of the application improves the activity and selectivity of the catalyst to the target product by adding a rare earth metal lanthanum compound as a regulator, thereby improving the yield of the product.

[0026] (3) The application reduces the amount of the supported solid base to the level of a catalyst, the supported solid base catalyst can be recycled and applied, thereby reducing production costs, improving economic benefits, and making the process clean and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 The gas chromatogram of the product citral prepared in Example 19 of the present application. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. The raw materials and devices used in the present application, if not specifically specified, are all conventional commercially available products; the methods used, if not specifically specified, are all conventional methods.

[0030] (I) Supported solid base catalyst and its preparation method

[0031] Example 1

[0032] A preparation method of a supported solid base catalyst, comprising the following steps:

[0033] 1g of lithium hydroxide was mixed with 49g of aqueous ammonia to form an aqueous solution, then 0.1g of lanthanum oxide was added and stirred until completely dissolved, then 20g of zirconium dioxide was added and heated to 40℃ for 2h for loading, after loading, filtration was performed, and the filter cake was dried at 100℃ for 180min to obtain a precursor; the precursor was calcined at 300℃ for 12h to obtain a supported solid base catalyst, which was named lithium hydroxide-lanthanum oxide-zirconium dioxide catalyst and stored for later use.

[0034] Example 2

[0035] A preparation method of a supported solid base catalyst, comprising the following steps:

[0036] 1g of sodium bicarbonate was mixed with 65g of aqueous ammonia to form an aqueous solution, then 0.2g of lanthanum chloride was added and stirred until completely dissolved, then 30g of silicon dioxide was added and heated to 45℃ for 3h for loading, after loading, filtration was performed, and the filter cake was dried at 100℃ for 180min to obtain a precursor; the precursor was calcined at 400℃ for 10h to obtain a supported solid base catalyst, which was named sodium bicarbonate-lanthanum chloride-silicon dioxide catalyst and stored for later use.

[0037] Example 3

[0038] A preparation method of a supported solid base catalyst, comprising the following steps:

[0039] 1g of calcium chloride was mixed with 99g of aqueous ammonia to form an aqueous solution, then 0.3g of lanthanum carbonate was added and stirred until completely dissolved, then 40g of aluminum oxide was added and heated to 50℃ for 4h for loading, after loading, filtration was performed, and the filter cake was dried at 100℃ for 180min to obtain a precursor; the precursor was calcined at 500℃ for 8h to obtain a supported solid base catalyst, which was named calcium chloride-lanthanum carbonate-aluminum oxide catalyst and stored for later use.

[0040] Example 4

[0041] A preparation method of a supported solid base catalyst, comprising the following steps:

[0042] 1g of potassium fluoride was mixed with 150g of aqueous ammonia to form an aqueous solution, then 0.4g of lanthanum acetate was added and stirred until completely dissolved, then 50g of SBA-15 was added and heated to 55℃ for 5h for loading, after loading, filtration was performed, and the filter cake was dried at 100℃ for 180min to obtain a precursor; the precursor was calcined at 600℃ for 6h to obtain a supported solid base catalyst, which was named potassium fluoride-lanthanum acetate-SBA-15 catalyst and stored for later use.

[0043] Example 5

[0044] A preparation method of a supported solid base catalyst, comprising the following steps:

[0045] 1g of magnesium oxide is mixed with 250g of ammonia water to configure an aqueous solution, then 0.5g of lanthanum nitrate is added and stirred until completely dissolved, 60g of Al-MCM-41 is then added, and loading is performed by heating to 65℃ for 6h under stirring, after the loading is completed, filtration is performed, the filter cake is dried at 100℃ for 180min to obtain a precursor, the precursor is calcined at 700℃ for 4h to obtain a supported solid base catalyst, which is named as a magnesium oxide-lanthanum nitrate-Al-MCM-41 catalyst and is stored for standby use.

[0046] Example 6

[0047] A preparation method of a supported solid base catalyst, comprising the following steps:

[0048] 1g of cesium carbonate is mixed with 300g of ammonia water to configure an aqueous solution, then 0.05g of lanthanum hydroxide is added and stirred until completely dissolved, 70g of zirconium dioxide is then added, and loading is performed by heating to 70℃ for 7h under stirring, after the loading is completed, filtration is performed, the filter cake is dried at 100℃ for 180min to obtain a precursor, the precursor is calcined at 800℃ for 5h to obtain a supported solid base catalyst, which is named as a cesium carbonate-lanthanum hydroxide-zirconium dioxide catalyst and is stored for standby use.

[0049] Example 7

[0050] A preparation method of a supported solid base catalyst, comprising the following steps:

[0051] 1g of barium chloride is mixed with 500g of ammonia water to configure an aqueous solution, then 0.01g of lanthanum chloride is added and stirred until completely dissolved, 80g of silicon dioxide is then added, and loading is performed by heating to 75℃ for 8h under stirring, after the loading is completed, filtration is performed, the filter cake is dried at 100℃ for 180min to obtain a precursor, the precursor is calcined at 900℃ for 4h to obtain a supported solid base catalyst, which is named as a barium chloride-lanthanum chloride-silicon dioxide catalyst and is stored for standby use.

[0052] Example 8

[0053] A preparation method of a supported solid base catalyst, comprising the following steps:

[0054] Mixing 1 g of potassium acetate with 700 g of ammonia water to form an aqueous solution, then adding 0.005 g of lanthanum oxide, stirring until completely dissolved, then adding 90 g of aluminum oxide, heating to 80℃ under stirring for 7 h for loading, after the loading is completed, filtering, and drying the filter cake at 100℃ for 180 min to obtain a precursor; placing the precursor in a furnace and calcining at 1000℃ for 3 h to obtain a supported solid base catalyst, which is named as potassium acetate-lanthanum oxide-aluminum oxide catalyst and stored for later use.

[0055] Example 9

[0056] A method for preparing a supported solid base catalyst, comprising the following steps:

[0057] Mixing 1 g of sodium acetate trihydrate with 900 g of ammonia water to form an aqueous solution, then adding 0.001 g of lanthanum carbonate, stirring until completely dissolved, then adding 100 g of SBA-15, heating to 50℃ under stirring for 6 h for loading, after the loading is completed, filtering, and drying the filter cake at 100℃ for 180 min to obtain a precursor; placing the precursor in a furnace and calcining at 900℃ for 2 h to obtain a supported solid base catalyst, which is named as sodium acetate trihydrate-lanthanum carbonate-SBA-15 catalyst and stored for later use.

[0058] In order to more intuitively compare the supported solid base catalysts of Examples 1-9 and their preparation process parameters, the following Table 1 is formed.

[0059] Table 1 Supported solid base catalysts of Examples 1-9 and their preparation process parameters

[0060]

[0061] (B) Application of the supported solid base catalyst in the preparation of citral nitrile

[0062] Example 10

[0063] An application of a supported solid base catalyst in the preparation of citral nitrile, comprising the following steps:

[0064] Into a reaction bottle with a thermometer and mechanical stirring, 100 g of 6-methyl-5-heptene-2-ketone, 16.26 g of acetonitrile, and 40 g of lithium hydroxide-lanthanum oxide-zirconium oxide catalyst were added, heated to 35℃ under stirring for 22 h for condensation reaction, after the reaction was completed, the temperature was lowered to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse, and the filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150℃ to obtain 54.47 g of citral nitrile, which was subjected to gas phase detection, and the gas phase purity was measured to be 99.96%, and the yield was 92.08% (calculated based on acetonitrile).

[0065] The reaction equation is as follows:

[0066]

[0067] Example 11

[0068] Use of a supported solid base catalyst in the preparation of citral nitrile, comprising the steps of:

[0069] Into a reaction flask with thermometer and mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 22.77 g of acetonitrile, 30 g of sodium bicarbonate-lanthanum chloride-silicon dioxide catalyst, 600 g of toluene were added, heated to 45°C under stirring for 19 h to carry out the condensation reaction, after the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse, and the filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 70.88 g of citral nitrile with a gas phase purity of 99.82% and a yield of 85.48% (calculated based on acetonitrile).

[0070] Example 12

[0071] Use of a supported solid base catalyst in the preparation of citral nitrile, comprising the steps of:

[0072] Into a reaction flask with thermometer and mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 29.27 g of acetonitrile, 40 g of calcium chloride-lanthanum carbonate-aluminum trioxide catalyst, 500 g of dimethylbenzene were added, heated to 55°C under stirring for 16 h to carry out the condensation reaction, after the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse, and the filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 86.83 g of citral nitrile with a gas phase purity of 99.84% and a yield of 81.46% (calculated based on acetonitrile).

[0073] Example 13

[0074] Use of a supported solid base catalyst in the preparation of citral nitrile, comprising the steps of:

[0075] Into a reaction flask with thermometer and mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 48.79 g of acetonitrile, 30 g of potassium fluoride-lanthanum acetate-SBA-15 catalyst, 400 g of trimethylbenzene were added, heated to 65°C under stirring for 13 h to carry out the condensation reaction, after the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse, and the filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 158.77 g of citral nitrile with a gas phase purity of 99.44% and a yield of 89.01% (calculated based on 6-methyl-5-hepten-2-one).

[0076] Example 14

[0077] Use of a supported solid base catalyst in the preparation of citral nitrile, comprising the following steps:

[0078] Into a reaction flask with thermometer and mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 65.06 g of acetonitrile, 20 g of magnesium oxide-lanthanum nitrate-Al-MCM-41 catalyst, 300 g of cyclohexane were added, and the condensation reaction was carried out by heating to 75°C for 10 h under stirring. After the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse. The filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 110.30 g of citral nitrile with a gas phase purity of 99.24% and a yield of 92.57% (calculated based on 6-methyl-5-hepten-2-one).

[0079] Example 15

[0080] Use of a supported solid base catalyst in the preparation of citral nitrile, comprising the following steps:

[0081] Into a reaction flask with thermometer and mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 81.32 g of acetonitrile, 10 g of cesium carbonate-lanthanum hydroxide-zirconium oxide catalyst, 200 g of ethanol were added, and the condensation reaction was carried out by heating to 85°C for 7 h under stirring. After the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse. The filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 97.99 g of citral nitrile with a gas phase purity of 99.44% and a yield of 82.41% (calculated based on 6-methyl-5-hepten-2-one).

[0082] Example 16

[0083] Use of a supported solid base catalyst in the preparation of citral nitrile, comprising the following steps:

[0084] Into a reaction flask with thermometer and mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 97.58 g of acetonitrile, 5 g of barium chloride-lanthanum chloride-silicon dioxide catalyst, 100 g of n-propanol were added, and the condensation reaction was carried out by heating to 95°C for 4 h under stirring. After the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse. The filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 88.89 g of citral nitrile with a gas phase purity of 99.27% and a yield of 74.62% (calculated based on 6-methyl-5-hepten-2-one).

[0085] Example 17

[0086] Use of a supported solid base catalyst in the preparation of citral, comprising the following steps:

[0087] Into a reaction flask with thermometer, mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 113.85 g of acetonitrile, 1 g of potassium acetate-lanthana-aluminum oxide catalyst, 50 g of isopropyl alcohol were added, heated to 105°C under stirring for 1 h to carry out the condensation reaction, after the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse. The filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 110.61 g of citral, with a gas phase purity of 99.13% and a yield of 92.73% (calculated based on 6-methyl-5-hepten-2-one).

[0088] Example 18

[0089] Use of a supported solid base catalyst in the preparation of citral, comprising the following steps:

[0090] Into a reaction flask with thermometer, mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 130.11 g of acetonitrile, 20 g of sodium acetate trihydrate-lanthana-SBA-15 catalyst, 30 g of n-butanol were added, heated to 115°C under stirring for 1 h to carry out the condensation reaction, after the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse. The filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 108.98 g of citral, with a gas phase purity of 99.06% and a yield of 91.29% (calculated based on 6-methyl-5-hepten-2-one).

[0091] Example 19

[0092] Use of a supported solid base catalyst in the preparation of citral, comprising the following steps:

[0093] Into a reaction flask with thermometer, mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 162.64 g of acetonitrile, 20 g of lithium hydroxide-lanthana-zirconia catalyst, 10 g of cyclohexanol were added, heated to 125°C under stirring for 1 h to carry out the condensation reaction, after the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was recovered to obtain the catalyst for reuse. The filtrate was subjected to rectification separation and purification at 1-4 KPa and 100-150°C to obtain 113.09 g of citral, with a gas phase purity of 99.76% and a yield of 95.41% (calculated based on 6-methyl-5-hepten-2-one).

[0094] Comparative Example 1

[0095] Use of a catalyst in the preparation of citral, comprising the following steps:

[0096] Into a reaction flask with thermometer, mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 162.64 g of acetonitrile, 20 g of lithium hydroxide solid, 10 g of cyclohexanol, heated to 125℃ for 1 h under stirring to carry out the condensation reaction, after the reaction, reduced to room temperature, filtered, the filter cake was recovered to obtain the catalyst for reuse, the filtrate was placed under 1-4 KPa, 100-150℃ for rectification separation and purification, 38.99 g of citral was obtained, the gas phase purity was 99.06%, the yield was 32.66% (calculated from 6-methyl-5-hepten-2-one).

[0097] Comparative Example 2

[0098] The use of a catalyst in the preparation of citral, comprising the following steps:

[0099] Into a reaction flask with thermometer, mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 162.64 g of acetonitrile, 20 g of zirconium oxide solid, 10 g of cyclohexanol, heated to 125℃ for 1 h under stirring to carry out the condensation reaction, after the reaction, reduced to room temperature, filtered, the filter cake was recovered to obtain the catalyst for reuse, the filtrate was sampled for gas phase detection, showing no product citral was generated.

[0100] Comparative Example 3

[0101] The use of a supported solid base catalyst in the preparation of citral, comprising the following steps:

[0102] Into a reaction flask with thermometer, mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 162.64 g of acetonitrile, 20 g of lithium hydroxide-zirconium oxide catalyst, 10 g of cyclohexanol, heated to 125℃ for 1 h under stirring to carry out the condensation reaction, after the reaction, reduced to room temperature, filtered, the filter cake was recovered to obtain the catalyst for reuse, the filtrate was placed under 1-4 KPa, 100-150℃ for rectification separation and purification, 66.56 g of citral was obtained, the gas phase purity was 99.67%, the yield was 56.10% (calculated from 6-methyl-5-hepten-2-one).

[0103] The preparation method of the lithium hydroxide-zirconium oxide catalyst, comprising the following steps:

[0104] 1 g of lithium hydroxide was mixed with 49 g of ammonia water to form an aqueous solution, then 20 g of zirconium dioxide was added, heated to 40℃ for 2 h under stirring to carry out the loading, after the loading was completed, filtered, the filter cake was dried at 100℃ for 180 min to obtain a precursor; the precursor was calcined at 300℃ for 12 h to obtain a supported solid base catalyst, which was named as lithium hydroxide-zirconium oxide catalyst and stored for use.

[0105] In order to more intuitively compare the effects of the supported solid base catalysts of Examples 10-19 and Comparative Examples 1-3 on the yield of citral, the following Table 2 is formed.

[0106] Table 2 Effects of supported solid base catalysts of Examples 10-19 and Comparative Examples 1-3 on the yield of citral

[0107]

[0108] From Table 2, it can be seen that:

[0109] Comparing Example 19 with Comparative Examples 1-3, it can be seen that the yields of citral of Comparative Examples 1-3 are much lower than that of Example 19, indicating that the catalysts using the active component or the carrier have very low or even no activity, and cannot completely catalyze the condensation reaction of 6-methyl-5-hepten-2-one and acetonitrile to generate citral, so it can be known that the synergistic effect of the active component and the carrier in the supported solid base catalyst has a great influence on the activity of the catalyst; the yield of citral is improved when the carrier loaded with the active component is used as the catalyst, but it is still low, so it can be known that the addition of the regulator significantly improves the activity of the catalyst.

[0110] Comparing Examples 10-19, it can be seen that the supported solid base catalyst prepared by the present application has excellent catalytic activity, can catalyze the condensation reaction of 6-methyl-5-hepten-2-one and acetonitrile to generate citral, and significantly improves the yield of the product, and the yield of the product citral is up to 95% or more.

[0111] The product prepared in Example 19 is detected, and the gas chromatogram thereof is as shown in Figure 1 From Figure 1 it can be seen that the peak time of the product is 3.801 min, the content of the main peak at the peak time of 3.801 min is 99.76%, and the chromatographic peak at 3.801 min is the same as the main peak in the citral standard sample, so it can be known that the chromatographic peak at 3.801 min is the product citral, and the gas phase purity thereof is 99.76%.

[0112] (III) Recycling performance of the supported solid base catalyst in the preparation of citral

[0113] Example 20

[0114] Into a reaction flask with thermometer and mechanical stirring, 100 g of 6-methyl-5-hepten-2-one, 163 g of acetonitrile, 42 g of wet lithium hydroxide-lanthanum oxide-zirconium oxide catalyst recovered from Example 19, and 10 g of cyclohexanol were added. The condensation reaction was carried out by heating to 125°C for 1 h under stirring. After the reaction, the temperature was lowered to room temperature, and the mixture was filtered. The filter cake was recovered to obtain the catalyst for reuse. The filtrate was subjected to rectification and purification under 1-4 KPa and 100-150°C to obtain citral. The citral was subjected to gas phase detection to measure the gas phase purity, and the yield (calculated based on 6-methyl-5-hepten-2-one) was calculated.

[0115] The lithium hydroxide-lanthanum oxide-zirconium oxide catalyst was recovered and reused for 10 times according to the above procedure. The results of the recycling performance of the lithium hydroxide-lanthanum oxide-zirconium oxide catalyst used for 11 times are shown in Table 3.

[0116] Table 3 Recycling performance of lithium hydroxide-lanthanum oxide-zirconium oxide catalyst

[0117]

[0118]

[0119] As can be seen from Table 3, the lithium hydroxide-lanthanum oxide-zirconium oxide catalyst has excellent recycling performance. The yield of citral does not decrease significantly after being recycled for 11 times.

[0120] The present application provides a supported solid base catalyst, a preparation method and application thereof. Compared with the prior art, (1) the present application uses a supported solid base as a catalyst to catalyze the condensation reaction of 6-methyl-5-hepten-2-one and acetonitrile to generate citral, thereby inhibiting the occurrence of self-condensation reaction of 6-methyl-5-hepten-2-one, improving the utilization rate of raw materials and the yield of products, and eliminating or reducing the generation of by-products, simplifying the post-processing process, reducing the production cost, and being environmentally friendly; (2) the supported solid base catalyst of the present application improves the activity and selectivity of the catalyst to the target product by adding a rare earth metal lanthanum compound as a regulator, thereby improving the yield of the product; (3) the present application reduces the amount of supported solid base to the level of a catalyst, and the supported solid base catalyst can be recycled and reused, thereby reducing the production cost, improving the economic benefit, and being clean and environmentally friendly. The present application can be widely applied in the field of organic synthesis technology.

[0121] It should be noted that:

[0122] The supported solid base catalyst of the application can catalyze the condensation reaction of 6-methyl-5-heptene-2-ketone and acetonitrile to generate citral, and citral can be prepared into citronellal through selective hydrogenation reaction, realizing the co-production of citral and citronellal, improving the utilization rate of raw materials and the yield of citral, saving reaction equipment, reducing production cost, and realizing simple and efficient process flow, which is suitable for industrial production.

[0123] In addition, the supported solid base catalyst of the application can realize continuous production or intermittent production in the process of preparing citral and citronellal through condensation reaction and selective hydrogenation reaction; if continuous production is selected, the reaction liquid of the condensation reaction can be used as raw material for selective hydrogenation reaction; if intermittent production is selected, the reaction liquid of the condensation reaction can be filtered, separated and purified through rectification to obtain citral, and citral can be used as raw material for selective hydrogenation reaction; continuous production is preferred in industrial production, realizing the co-production of citral and citronellal, saving reaction equipment and reducing production cost.

[0124] The above examples are only used to illustrate the technical solutions of the application, but not limit the application; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent features; the modification or replacement does not change the essence of the corresponding technical solution, and should be included in the protection scope of the application.

Claims

1. Use of a supported solid base catalyst for the preparation of citralon, characterized in that, The method comprises the following steps: The 6-methyl-5-heptene-2-ketone, acetonitrile and the supported solid base catalyst are mixed, stirred, heated and kept for condensation reaction, after the reaction is completed, filtration is performed, and the filtrate is subjected to rectification to obtain citral; The supported solid base catalyst comprises a carrier, an active component and a regulator, the active component and the regulator are loaded on the carrier, the active component is an alkali metal compound or an alkaline earth metal compound, the regulator is a rare earth metal compound, and the carrier is a metal oxide or a molecular sieve with a large pore structure; The rare earth metal compound is a lanthanum compound, and the lanthanum compound is any one or a combination of at least two of lanthanum oxide, lanthanum chloride, lanthanum carbonate, lanthanum acetate, lanthanum nitrate, lanthanum hydroxide and a hydrate thereof; The alkali metal compound and the alkaline earth metal compound are any one or a combination of at least two of acid salts, oxides, hydroxides and hydrates of Li, Na, K, Ca, Ba, Mg and Cs, and the metal oxide and the molecular sieve with the large pore structure are any one or a combination of at least two of ZrO2, SiO2, Al2O3, SBA-15 and Al-MCM-41.

2. Use of the supported solid base catalyst according to claim 1 in the preparation of citral nitrile, characterized in that, The preparation method of the supported solid base catalyst comprises the following steps: The active component is mixed with ammonia water to prepare an aqueous solution, then the regulator is added, stirring is performed until the regulator is completely dissolved, the carrier is added, loading is performed by stirring and heating, after the loading is completed, filtration and drying are performed, a precursor is obtained, the precursor is calcined, and the supported solid base catalyst is obtained.

3. Use of the supported solid base catalyst according to claim 2 in the preparation of citral nitrile, characterized in that, The mass fraction of the active component in the aqueous solution is 0.1-2%, the mass ratio of the active component to the regulator is 1:0.001-1:0.5, and the mass ratio of the active component to the carrier is 1:20-1:

100.

4. Use of the supported solid base catalyst according to claim 2 in the preparation of citral nitrile, characterized in that, The heating temperature during loading is 40-80 DEG C, the holding time is 2-8 h, the calcination temperature is 300-1000 DEG C, and the calcination time is 2-12 h.

5. Use of the supported solid base catalyst according to claim 1 in the preparation of citral nitrile, characterized in that, The condensation reaction does not require a solvent.

6. Use of the supported solid base catalyst according to claim 1 in the preparation of citral nitrile, characterized in that, The solvent needs to be added before the condensation reaction, the solvent is any one of toluene, xylene, trimethylbenzene, cyclohexane, ethanol, n-propanol, isopropanol, n-butanol and cyclohexanol, the mass ratio of the 6-methyl-5-heptene-2-ketone to the solvent is 1:0.1-1:

6.

7. Use of the supported solid base catalyst according to claim 5 or 6 for the preparation of citral nitrile, characterized in that, The molar ratio of the 6-methyl-5-heptene-2-ketone to the acetonitrile is 1:0.5-1:5, the mass ratio of the 6-methyl-5-heptene-2-ketone to the supported solid base catalyst is 1:0.01-1:0.4, and the reaction temperature of the condensation reaction is 35-125 DEG C, and the reaction time is 1-22 h.

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