Method for preparing octanal from octenal

Abstract

The present invention relates to the technical field of preparing octanol, and discloses a method for preparing octanal from octenal, the method comprising: in the presence of a catalyst, contacting octenal with hydrogen to produce a hydrogenation reaction; wherein the catalyst is prepared by the following methods: (1) providing alumina microspheres, the particle diameter of the alumina microspheres being 200-800 μm, and the coefficient of variation being 3-8%; (2) mixing the alumina microspheres with sugar for carbonization to obtain a carrier; (3) loading a transition metal active component on the carrier. The method of the present invention is used to prepare octanal, and the conversion rate of octenal and the selectivity of octanal can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of preparing octanol, and in particular to a method for preparing octanal from octenal. Background Art

[0002] Octanal is an important chemical product. It is an important organic raw material or fragrance. It is widely present in plant essential oils and has potential antibacterial effects. This type of compound has many aroma types, with a pleasant sweet orange scent and a long lasting fragrance. It can increase the natural feel of the flavor. At the same time, octanal can be used as a citrus flavor in beverages and ice cream, and has a wide range of applications.

[0003] Octenal is an α,β-unsaturated aldehyde, which contains both C=C and C=O bonds in the molecule. The bond energy of C=C bond is 615kJ / mol, and the bond energy of C=O bond is 715kJ / mol. Therefore, based on the data comparison of computational chemistry, it is generally believed that the C=C double bond is easier to hydrogenate than the C=O double bond. Therefore, it is generally believed that octenal can be hydrogenated once to produce octanal, and octanal can only be hydrogenated twice to produce octanol. In theory, as long as the appropriate catalyst is selected and the reaction conditions are precisely controlled, octenal can be hydrogenated once to produce octanal. However, due to the uncontrollability of the actual reaction, it is inevitable that some octanal will be converted into octanol during the reaction.

[0004] At present, most of the research focuses on the hydrogenation of octenal to produce octanol, but there are few reports on the selective preparation of octanal. CN107930647A discloses a catalyst for preparing 2-ethylhexanal, comprising Al 2 O 3 The support, as well as the Al 2 O 3 The first metal component and the second metal component on the carrier, the first metal component is Ag, and one or two of Co and Rh; the second metal component is Pd; at the same time, CN107930647A also discloses a method for preparing 2-ethylhexanal, which includes heating the isooctene aldehyde feed to 180-220°C to gasify the isooctene aldehyde, and introducing hydrogen therein to obtain a mixed gas of gasified isooctene aldehyde and hydrogen, and then contacting the mixed gas with a catalyst to obtain 2-ethylhexanal. However, the active components of the catalyst disclosed in CN107930647A include a variety of precious metals, which will lead to an excessively high overall catalyst cost. At the same time, the isooctene aldehyde needs to be heated to 180-220°C to gasify the isooctene aldehyde, which will increase the energy consumption of the reaction. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems of the prior art and to provide a method for preparing octanal from octenal.

[0006] In order to achieve the above object, the present invention provides a method for preparing octanal from octenal, the method comprising: contacting octenal with hydrogen in the presence of a catalyst to cause a hydrogenation reaction;

[0007] Wherein, the catalyst is prepared by the following method:

[0008] (1) Providing alumina microspheres, wherein the particle diameter of the alumina microspheres is 200-800 μm and the coefficient of variation is 3-8%;

[0009] (2) mixing alumina microspheres with sugar and carbonizing them to obtain a carrier;

[0010] (3) Loading the transition metal active component on the carrier.

[0011] The present invention adopts specific alumina microspheres to carbonize and load active components to prepare a catalyst. The catalyst prepared by the method of the present invention can selectively generate octenal by reacting octenal with hydrogen at a relatively low temperature, and the conversion rate of octenal and the selectivity of octenal are relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 1 is a scanning electron microscope photograph of the alumina microspheres prepared in the preparation example.

[0013] Figure 2 This is the particle size distribution diagram of the alumina microspheres prepared in Preparation Example. DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] In the present invention, unless otherwise specified, the diameter of alumina microspheres refers to the average diameter of alumina microspheres.

[0016] The present invention provides a method for preparing octanal from octenal, the method comprising: in the presence of a catalyst, contacting octenal with hydrogen to cause a hydrogenation reaction;

[0017] Wherein, the catalyst is prepared by the following method:

[0018] (1) providing alumina microspheres, wherein the particle diameter of the alumina microspheres is 200-800 μm and the coefficient of variation is 3-8%;

[0019] (2) mixing alumina microspheres with sugar and carbonizing them to obtain a carrier;

[0020] (3) Loading the transition metal active component on the carrier.

[0021] According to the present invention, the source of the alumina microspheres is not particularly limited, as long as the particle diameter and coefficient of variation of the alumina microspheres meet the specified range. The alumina microspheres can be prepared by referring to the method in the literature, for example, the alumina microspheres can be prepared by referring to the method described in CN110203953B or CN110282642B. Preferably, the preparation method of the alumina microspheres comprises: using aluminum sol as a dispersed phase and an organic solvent as a continuous phase, forming droplets of the dispersed phase under the shearing action of the continuous phase, obtaining gel microspheres by solidification, and then obtaining alumina microspheres by drying and calcining.

[0022] In the method for preparing alumina microspheres according to the present invention, preferably, the aluminum sol has a solid content of 5-8 wt %.

[0023] In the method for preparing alumina microspheres according to the present invention, preferably, the organic solvent used in the process of preparing alumina microspheres is a C1-C10 monohydric saturated alcohol, preferably octanol.

[0024] In the method for preparing alumina microspheres according to the present invention, the drying temperature may be 80-140° C., and the drying time may be 3-15 h.

[0025] In the method for preparing alumina microspheres according to the present invention, the calcination temperature may be 550-1200° C., and the calcination time may be 4-10 h.

[0026] According to the present invention, preferably, the alumina microspheres are prepared in a microchannel reactor. There is no particular limitation on the type of the microchannel reactor, and the microchannel reactor is a single-channel reactor and / or a multi-channel reactor.

[0027] According to a further preferred embodiment of the present invention, the multi-channel reactor is an eight-channel reactor. The structure of the eight-channel reactor is described, and the eight-channel reactor includes a continuous phase distribution layer, a first droplet generation layer, a second droplet generation layer and a dispersed phase distribution layer, wherein the continuous phase distribution layer is composed of a petal-shaped resistance distribution channel and eight fluid outlets at its end, a continuous phase vertical inlet and four positioning holes, each branch of the fluid passing through is called a level, and a certain resistance is added before each level of fluid branch, and the width of the channel decreases as the radius of the circle where the starting end of each level is located increases; the first droplet generation layer is distributed with eight T-shaped channels, four positioning holes and eight through holes to meet the needs of the continuous phase flowing from the distribution layer to the generation layer, the second droplet generation layer is similar to the first droplet generation layer in structure, and eight droplet outlets are distributed at the end of the main channel of the T-shaped channel; the dispersed phase distribution layer is similar to the continuous phase distribution layer in structure, except for the petal-shaped resistance distribution channel and the eight dispersed phase outlets at its end, there is also a dispersed phase fluid inlet and 8 product outlets.

[0028] According to the present invention, preferably, an eight-channel reactor is used as an example to illustrate the process of preparing alumina microspheres of the present invention. Alumina sol is used as a dispersed phase, an organic solvent is used as a continuous phase, the flow rate of the continuous phase is adjusted, the continuous phase fills the continuous phase distribution layer and flows into the droplet generation layer, and then flows out from the outlet, the continuous phase flow rate is finally stabilized at 6-10mL / min, the dispersed phase flow rate is adjusted to 1-4mL / min, the dispersed phase fills the dispersed phase distribution layer and flows into the droplet generation layer, and droplets are further generated under the shearing action of the continuous phase, and the droplets are solidified in the oil column to obtain gel microspheres, which are dried and calcined to obtain alumina microspheres with a diameter of 200-800μm and a coefficient of variation of 3-8%.

[0029] According to the present invention, the amount of the sugar can be selected within a wide range. Preferably, relative to 100 g of alumina microspheres, the amount of the sugar is 1.5-9 g, preferably 3-6 g.

[0030] According to the present invention, preferably, the carbonization method is: contacting the alumina microspheres with a sugar-containing solution, and then performing a first calcination to obtain the carrier.

[0031] According to the present invention, the conditions for contacting the alumina microspheres with the sugar-containing solution can be selected within a wide range. Preferably, the temperature for contacting the alumina microspheres with the sugar-containing solution is 15-30° C. and the time is 0.1-1 h.

[0032] According to the present invention, the conditions for the first calcination can be selected within a wide range. Preferably, the temperature of the first calcination is 600-1200° C., preferably 750-850° C., and the time is 4-10 h.

[0033] According to the present invention, preferably, the carbonization method further comprises a first drying before the first calcination, and more preferably, the first drying temperature is 80-140° C. and the time is 3-10 h.

[0034] According to the present invention, preferably, the first calcination is performed in the presence of an inert gas.

[0035] According to the present invention, the type of sugar can be selected from a wide range. Preferably, the sugar is at least one of monosaccharide, disaccharide and polysaccharide, more preferably glucose and / or sucrose.

[0036] According to the present invention, the concentration of sugar in the sugar-containing solution is not particularly limited. Preferably, the concentration of sugar in the sugar-containing solution is 2.5-10wt% (for example, it can be 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%).

[0037] According to the present invention, preferably, the amount of the transition metal active component calculated as the metal element is 0.5-4 g, preferably 0.6-3 g, relative to 20 g of the carrier.

[0038] According to the present invention, preferably, the transition metal active component is at least one of Ni, Cu and Co.

[0039] According to the present invention, preferably, the amount of the transition metal active component used is such that the content of the transition metal active component in the obtained catalyst, calculated as the metal element, is 2.5-15 wt %.

[0040] According to the present invention, preferably, the transition metal active component is loaded on the carrier by impregnating the carrier with an impregnation solution containing the transition metal active component, and then performing a second calcination.

[0041] According to the present invention, preferably, the impregnation solution containing transition metal active components is prepared by dissolving a water-soluble salt of a transition metal in water. More preferably, the mass percentage of the water-soluble salt of a transition metal in the impregnation solution containing transition metal active components is 5-20wt%.

[0042] According to the present invention, the conditions for the impregnation with the impregnation liquid can be selected within a wide range. Preferably, the impregnation temperature is 15-30° C. and the impregnation time is 0.1-1 h.

[0043] According to the present invention, the conditions for the second calcination can be selected within a wide range. Preferably, the temperature of the second calcination is 300-450° C. and the time is 3-10 h.

[0044] According to the present invention, preferably, the method of loading the transition metal active component on the carrier further includes performing a second drying before the second calcination. More preferably, the temperature of the second drying is 80-140° C. and the time is 3-10 h.

[0045] According to the present invention, preferably, the second calcination is performed in the presence of an inert gas.

[0046] According to the present invention, preferably, the inert gas used in the first calcination and the second calcination is independently at least one of nitrogen, helium and argon.

[0047] According to the present invention, preferably, the conditions of the hydrogenation reaction include: temperature of 50-100° C., hydrogen pressure of 2-4 MPa, and reaction time of 5-20 h.

[0048] According to the present invention, preferably, the octenal is contacted with hydrogen in the form of an octenal solution, and the solvent in the octenal solution is a C1-C4 saturated alcohol.

[0049] According to the present invention, preferably, the amount of octenal used is 0.5-2.5 g per gram of catalyst.

[0050] In the present invention, the reaction of preparing octanal by hydrogenating octenal is a liquid phase reaction.

[0051] According to the present invention, preferably, the weight ratio of octenal to C1-C4 saturated alcohol is 1:8-25.

[0052] According to the present invention, the C1-C4 saturated alcohol may be an alcohol commonly used in the art. Preferably, the C1-C4 saturated alcohol is ethanol (anhydrous ethanol).

[0053] In the present invention, the method further comprises reducing the catalyst, and then carrying out the reaction of preparing octanal by hydrogenating octenal. The method for reducing the catalyst may be a method commonly used in the art, and preferably, the method for reducing the catalyst comprises: loading the catalyst into a stainless steel fixed bed reactor, introducing high-purity nitrogen at a flow rate of 200-400 mL / min, heating to 100-150° C., switching the high-purity nitrogen to hydrogen at a flow rate of 100-300 mL / min, heating to 400-450° C. and maintaining for 3-5 h to obtain the reduced catalyst.

[0054] According to a particularly preferred embodiment of the present invention, the method for preparing octanal by hydrogenation of octenal comprises:

[0055] (1) 100 g of alumina microspheres with a diameter of 200-400 μm and a coefficient of variation of 7-8% are immersed in a 5-7 wt % glucose aqueous solution, wherein the amount of glucose is 3-4 g, and immersed at 25-30° C. for 0.1-0.5 h. The immersed alumina microspheres are dried at 120-130° C. for 4-5 h, and then carbonized at 800-820° C. for 8-9 h under the protection of nitrogen to obtain a carrier.

[0056] (2) 20 g of the carrier is placed in an 8-11 wt % nickel nitrate aqueous solution, wherein the amount of the nickel nitrate solution used is 0.8-1.2 g in terms of metallic nickel element, and the mixture is immersed at 15-30° C. for 10-30 min, then taken out, dried at 95-105° C. for 3-5 h, and calcined at 400-450° C. for 3-3.5 h under the protection of nitrogen to obtain a catalyst.

[0057] (3) Then, in the presence of the prepared catalyst, octenal is subjected to a hydrogenation reaction with hydrogen; the conditions of the hydrogenation reaction include: a temperature of 55-65° C., a hydrogen pressure of 2-2.5 MPa, a reaction time of 10-20 h, an amount of octenal of 2.2-2.5 g per gram of catalyst, and a weight ratio of octenal to ethanol of 1:14-15.

[0058] The present invention will be described in detail below by way of examples. In the following examples,

[0059] Octenal conversion rate = (the number of moles of octenal in the raw material - the number of moles of unreacted octenal) ÷ ​​the number of moles of octenal in the raw material × 100%.

[0060] Octanal selectivity = the number of moles of octanal in the product ÷ (the number of moles of octenal in the raw material - the number of moles of unreacted octenal) × 100%.

[0061] The diameter of alumina microspheres was measured by scanning electron microscopy.

[0062] The test method of the coefficient of variation is as follows: the number of alumina microspheres in a unit area is measured by scanning electron microscopy, and the diameter of each alumina microsphere is measured, and then the coefficient of variation is calculated according to the formula.

[0063] The coefficient of variation was calculated according to the following formula:

[0064]

[0065] CV: coefficient of variation, n: alumina microsphere particle count, X i : single alumina microsphere particle diameter, The average particle diameter of all alumina microspheres.

[0066] Preparation Example

[0067] Alumina microspheres were prepared using a microstructured reactor device. The dispersed phase was selected as aluminum sol with a solid content of 7.5wt%, and the continuous phase and the liquid in the oil column were selected as organic solvent octanol. The continuous phase flow rate was first adjusted so that the continuous phase filled the continuous phase distribution layer and flowed into the droplet generation layer, and then flowed out from the outlet. The continuous phase flow rate was finally stabilized at 6-10mL / min. Then the dispersed phase flow rate was adjusted to 1-4mL / min, so that the dispersed phase filled the dispersed phase distribution layer and flowed into the droplet generation layer, and droplets were further generated under the shearing action of the continuous phase. The droplets solidified in the oil column to obtain gel microspheres, and after drying at 120°C for 12h and calcining at 600°C for 4h, alumina microspheres with a diameter of 345μm and a coefficient of variation of 7.2% were obtained.

[0068] Among them, the scanning electron microscope image of alumina microspheres is as follows Figure 1 As shown, the diameter of the alumina microspheres is in the range of 300-400 μm, and they are uniform spherical particles.

[0069] Among them, the particle size distribution diagram of alumina microspheres is as follows Figure 2 As shown by Figure 2 It can be seen that the particle size distribution range of alumina microspheres is very narrow.

[0070] Example 1

[0071] (1) 100 g of the alumina microspheres obtained in the preparation example were immersed in a 6 wt % glucose aqueous solution (wherein the amount of the glucose aqueous solution was 50 g), and after immersion at 25° C. for 0.2 h, the impregnated alumina microspheres were placed in a 130° C. oven for drying for 4 h, and then placed in a tubular furnace and carbonized at 810° C. for 9 h under the protection of nitrogen to obtain a carrier (carbonized alumina microspheres).

[0072] (2) 20 g of the carrier was placed in a 10 wt % nickel nitrate aqueous solution (wherein the amount of the nickel nitrate aqueous solution calculated as metallic nickel element was 1 g), immersed at 25° C. for 20 min, taken out, drained, dried at 100° C. for 5 h, and calcined at 450° C. for 3 h under the protection of nitrogen to obtain a catalyst.

[0073] XRF characterization showed that the nickel loading in the catalyst was 4.8 wt%.

[0074] Example 2

[0075] (1) 100 g of the alumina microspheres obtained in the preparation example were immersed in a 9 wt % glucose aqueous solution (wherein the amount of the glucose aqueous solution was 70 g), and after immersion at 25° C. for 1 h, the impregnated alumina microspheres were placed in a 130° C. oven for drying for 8 h, and then placed in a tubular furnace and carbonized at 760° C. for 4 h under the protection of argon to obtain a carrier (carbonized alumina microspheres).

[0076] (2) 20 g of the carrier was placed in a 12 wt% copper nitrate aqueous solution (the amount of the copper nitrate aqueous solution calculated as metallic copper element was 0.6 g), immersed at 25° C. for 20 min, taken out, drained, dried at 110° C. for 6 h, and calcined at 350° C. for 4 h under the protection of argon to obtain a catalyst.

[0077] XRF characterization showed that the copper loading in the catalyst was 3wt%.

[0078] Example 3

[0079] (1) 100 g of the alumina microspheres obtained in the preparation example were immersed in a 3 wt % glucose aqueous solution (wherein the amount of the glucose aqueous solution was 90 g), and after immersion at 20° C. for 0.8 h, the impregnated alumina microspheres were placed in a 100° C. oven for drying for 4 h, and then placed in a tubular furnace and carbonized at 840° C. for 6 h under the protection of helium to obtain a carrier (carbonized alumina microspheres).

[0080] (2) 20 g of the carrier was placed in a 20 wt % cobalt nitrate aqueous solution (the amount of the cobalt nitrate aqueous solution calculated as metallic cobalt element was 2.8 g), immersed at 25° C. for 20 min, taken out, drained, dried at 90° C. for 8 h, and calcined at 380° C. for 10 h under the protection of helium to obtain a catalyst.

[0081] XRF characterization showed that the cobalt loading in the catalyst was 12.3 wt%.

[0082] Comparative Example 1

[0083] The catalyst was prepared according to the method of Example 1, except that the alumina microspheres were replaced with alumina tooth balls (purchased from Inokai Biotechnology Co., Ltd., with a particle size of 3-4 mm).

[0084] XRF characterization showed that the nickel loading in the catalyst was 4.8 wt%.

[0085] Comparative Example 2

[0086] The catalyst was prepared according to the method of Example 1, except that the process of carbonizing the alumina microspheres in step (1) was not included.

[0087] XRF characterization showed that the nickel loading in the catalyst was 4.8 wt%.

[0088] Comparative Example 3

[0089] The catalyst was prepared according to the method of Example 1 in CN107930647A to obtain hydrogenation catalyst No. 1 (Pd-Ag-Co / Al 2 O 3 -MgO).

[0090] Test Case

[0091] Catalyst reduction process: 10 mL of catalyst was loaded into a stainless steel fixed bed reactor, high-purity nitrogen was introduced at a flow rate of 300 mL / min, the temperature was raised to 120°C, the high-purity nitrogen was switched to hydrogen at a flow rate of 200 mL / min, the temperature was raised to 430°C and maintained for 4 hours to reduce the catalyst, and then the temperature was slowly lowered to room temperature, and the reactor was opened to unload the reduced catalyst.

[0092] 1 g of the reduced catalyst was placed in a reactor to carry out the reaction of preparing octanal by hydrogenation of octenal. The addition amounts of the raw materials octenal and anhydrous ethanol, the reaction temperature and the hydrogen pressure were shown in Table 1. The reaction time was 10 h. The test results are shown in Table 1.

[0093] Table 1

[0094]

[0095] It can be seen from the results in Table 1 that the method of the present invention can improve the conversion rate of octenal and the selectivity of octenal when preparing octenal. In particular, when octenal is prepared by the method of Example 1 of the present invention, the conversion rate of octenal can reach 90% and the selectivity of octenal can reach 74%.

[0096] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing octanal from octenal, characterized in that: The method comprises: in the presence of a catalyst, contacting octenal with hydrogen to cause a hydrogenation reaction; Wherein, the catalyst is prepared by the following method: (1) Providing alumina microspheres, wherein the particle diameter of the alumina microspheres is 200-800 μm and the coefficient of variation is 3-8%; (2) mixing alumina microspheres with sugar and carbonizing them to obtain a carrier; (3) Loading the transition metal active component on the carrier; The carbonization method is: contacting the alumina microspheres with a sugar-containing solution, and then performing a first calcination to obtain a carrier, wherein the first calcination is performed in the presence of an inert gas; The transition metal active component is at least one of Ni, Cu and Co; the transition metal active component is loaded on the carrier by impregnating the carrier with an impregnation solution containing the transition metal active component, and then performing a second calcination, wherein the second calcination is performed in the presence of an inert gas; Relative to 100 g of alumina microspheres, the amount of the sugar used is 1.5-9 g.

2. The method according to claim 1, wherein: Relative to 100 g of alumina microspheres, the amount of the sugar used is 3-6 g.

3. The method according to claim 1, wherein: The sugar is at least one of monosaccharide, disaccharide and polysaccharide.

4. The method according to claim 1, wherein: The concentration of sugar in the sugar-containing solution is 2.5-10wt%.

5. The method according to claim 1, wherein: The first calcination is carried out at a temperature of 600-1200° C. and for a time of 4-10 hours.

6. The method according to claim 1, wherein: The sugar is glucose and / or sucrose.

7. The method according to claim 1, wherein: The temperature of the first calcination is 750-850° C. and the time is 4-10 hours.

8. The method according to claim 1, wherein: The temperature for contacting the alumina microspheres with the sugar-containing solution is 15-30° C. and the time is 0.1-1 h.

9. The method according to claim 1, wherein: The amount of the transition metal active component used is 0.5-4 g in terms of metal element relative to 20 g of the carrier.

10. The method according to claim 1, wherein: The amount of the transition metal active component used is 0.6-3 g in terms of metal element relative to 20 g of the carrier.

11. The method according to claim 1, wherein: The amount of the transition metal active component used is such that the content of the transition metal active component in the obtained catalyst, calculated as the metal element, is 2.5-15 wt %.

12. The method according to claim 1, wherein: The immersion temperature is 15-30°C and the immersion time is 0.1-1h.

13. The method according to claim 1, wherein: The second calcination temperature is 300-450° C. and the time is 3-10 hours.

14. The method according to claim 1, wherein: The inert gas used in the first calcination and the second calcination is independently at least one of nitrogen, helium and argon.

15. The method according to claim 1, wherein: The conditions of the hydrogenation reaction include: temperature of 50-100°C, hydrogen pressure of 2-4MPa, and reaction time of 5-20h; And / or, the amount of octenal used is 0.5-2.5 g per gram of catalyst; And / or, the octenal is contacted with hydrogen in the form of an octenal solution, and the solvent in the octenal solution is a C1-C4 saturated alcohol.

16. The method according to claim 15, wherein: The weight ratio of octenal to C1-C4 saturated alcohol is 1:8-25; And / or, the C1-C4 saturated alcohol is ethanol.

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