Method for preparing isooctanal through selective hydrogenation of isooctenal

Abstract

The invention belongs to the technical field of catalytic hydrogenation, and relates to a method for preparing isooctanal through selective hydrogenation of isooctenal. Isooctenal, hydrogen and a nickel catalyst are subjected to a contact reaction, and the nickel catalyst comprises a carrier aluminum oxide and an active component nickel dispersed on the carrier aluminum oxide; the preparation method comprises the following steps: jointly pumping an aluminum sulfate solution and an aluminum hydroxide-sodium hydroxide mixed solution into a rotation strengthening reactor by adopting a liquid pump to form suspension slurry; spraying the suspension slurry into the inner side of a silk screen filler through a solution mixing distributor, and rotating the silk screen filler to shear the suspension slurry into tiny units; enabling the tiny units to enter a crystallization kettle through an outlet of the rotary intensified reactor, crystallizing to obtain a crystallized material, filtering, washing, drying, and roasting to obtain the alumina carrier. The nickel component and the alumina carrier which are commonly used in the industry are used, the reaction condition is mild, the isooctanal selectivity is high, and certain industrial application prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic hydrogenation, and specifically relates to a method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde. Background Art

[0002] 2-Ethylhexanal (industrial name isooctanal) is an important chemical intermediate. It can be oxidized to generate isooctyl acid, which is used as a coating and resin modifier, or reduced to generate octanol, which is used to produce plasticizer dioctyl phthalate (DOP). At the same time, isooctyl aldehyde is also a flavor additive used in soaps and synthetic detergents.

[0003] At present, the industrial preparation of isooctyl aldehyde mainly includes propylene carbonyl synthesis and acetaldehyde aldol condensation. The propylene carbonyl synthesis method is to obtain butyraldehyde from propylene and synthesis gas under the action of cobalt or ruthenium catalyst, and then condense and dehydrate to obtain 2-ethyl-2-hexenal (industrially called isooctyl aldehyde), and finally obtain isooctyl aldehyde through selective hydrogenation. The acetaldehyde aldol condensation method uses acetaldehyde as raw material, obtains butyraldehyde through condensation, dehydration and hydrogenation, and the subsequent process is consistent with the propylene carbonyl synthesis method. In the preparation process of isooctyl aldehyde, the selective hydrogenation of isooctyl aldehyde is the key process. However, the highly selective hydrogenation of isooctene aldehyde to produce saturated octanal is still difficult and challenging, because the isooctene aldehyde molecule contains both C=O and C=C bonds. From a thermodynamic point of view, the bond energy of the C=O bond is 715 KJ / mol, the bond energy of the C=C bond is 615 KJ / mol, and the two have a conjugated effect; from a kinetic point of view, it is difficult to hydrogenate only the C=C bond without hydrogenating the C=O bond.

[0004] Precious metal palladium is a commonly used precious metal hydrogenation active component in industry. Due to its special valence electron structure, it has excellent catalytic hydrogenation activity.

[0005] However, most of the carriers of palladium catalysts in the prior art are mainly inorganic carrier alumina. US4018831A uses Pd-Ni / Al2O3 catalyst, isooctylaldehyde is catalytically hydrogenated at 90-180°C and 0.7-3.5MPa pressure to produce isooctylaldehyde, with a space velocity of 0.5-3 and a hydrogen-oil ratio of 2:1-3:1 (mol / mol). By controlling the hydrogen flow rate and reaction conditions to make the liquid phase flow upward through the catalyst bed, the selectivity of the target product is improved and the generation of the byproduct isooctyl alcohol is reduced. However, the isooctylaldehyde conversion rate is 74%, the isooctylaldehyde selectivity is 97.5%, and the overall yield of the target product is low.

[0006] CN107930647B discloses a catalyst with Al2O3 as carrier, loaded with Pd and Ag, and one or two of Co and Rh, wherein the Pd content is 0.01-1.0wt%, and the total content of Ag, Co and Rh is 0.01-0.5wt‰. Under the conditions of temperature of 180-220℃, pressure of 0.5-2MPa, space velocity of 30g / (g·h), and molar ratio of hydrogen to aldehyde group of 2-15:1 based on the total mass of the gasified part of isooctylaldehyde, the conversion rate of isooctylaldehyde can reach 99%, and the selectivity of isooctylaldehyde can also reach 99%. However, the catalyst is used for gas phase reaction, and the reaction temperature is too high.

[0007] CN201811205777.6 discloses a Pd-polymer composite catalyst, which has a high conversion rate and selectivity for the selective hydrogenation of isooctylaldehyde to prepare isooctylaldehyde. However, the application range of the polymer carrier is limited, and the precious metal palladium is used, which is expensive and has no industrial application prospects.

[0008] Metal Ni catalysts are widely used hydrogenation catalysts in the oil refining and chemical industries, but the activity of Ni catalysts is too high, which can easily cause unsaturated aldehydes to be completely hydrogenated to form saturated alcohols, resulting in a low yield of saturated aldehydes.

[0009] GB 1102796A discloses a Ni / diatomaceous earth catalyst, which uses sulfide to partially poison the Ni catalyst to improve the selectivity of saturated aldehydes. When the catalyst is used for the hydrogenation reaction of isooctene aldehyde, the conversion rate of isooctene aldehyde reaches 98% and the selectivity reaches 97%. However, the reaction is a gas phase hydrogenation reaction, which requires a relatively high temperature of 225°C and has a side reaction of raw material cracking.

[0010] CN202011152640.6 discloses a sulfur-doped carbon-loaded nickel-based catalyst, in which the carrier carbon is obtained by polymer carbonization, and the doped sulfur element is obtained by decomposing the cross-linking agent sulfuric acid. Sulfur poisons the Ni in the catalyst and improves the selectivity of isooctylaldehyde, which can reach up to about 90%. However, the carbonization of polymers will generate a large amount of alkanes and tars, which consumes a lot of energy and causes high pollution, and has no prospects for industrial application.

[0011] CN114082421A discloses an alumina-supported nickel catalyst, which has high activity in the octenal hydrogenation reaction, the conversion rate of octenal can reach 100%, and the yield of octanal can reach 98%, but the reaction temperature needs to be 100°C.

[0012] In summary, the catalysts in the prior art need to be subjected to high temperature conditions to achieve the purpose of high isooctyl aldehyde selectivity. There is an urgent need to provide a catalyst with high isooctyl aldehyde selectivity and mild reaction conditions. Summary of the invention

[0013] In order to solve the problems in the prior art, the present invention provides a method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde. The present invention has mild reaction conditions, high isooctyl aldehyde selectivity, uses commonly used nickel components and alumina carriers in industry, and has certain industrial application prospects.

[0014] In order to achieve the above object, the present invention provides a method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde, wherein isooctyl aldehyde, hydrogen and a nickel catalyst are contacted and reacted, wherein the nickel catalyst comprises a carrier alumina and an active component nickel dispersed thereon;

[0015] The preparation method of the carrier alumina is carried out by using a rotary strengthening device, which includes: a rotary strengthening reactor, at least two liquid pumps, a crystallization kettle and a motor;

[0016] The rotary enhanced reactor comprises a rotary enhanced reaction device shell, a wire mesh filler and a solution mixing distributor, wherein the wire mesh filler is located inside the rotary enhanced reaction device shell, and a certain space is formed inside the wire mesh filler, the solution mixing distributor is placed in the space, and the motor is connected to the wire mesh filler;

[0017] The liquid pump is provided with a liquid pump discharge pipeline, the rotary enhanced reaction device housing is provided with a rotary enhanced reactor inlet and a rotary enhanced reactor outlet, the liquid pump discharge pipeline is connected to the solution mixing distributor through the rotary enhanced reactor inlet, and the rotary enhanced reactor outlet is connected to the crystallization kettle;

[0018] The steps include:

[0019] (1) using a liquid pump to pump the aluminum sulfate solution and the aluminum hydroxide-sodium hydroxide mixed solution from the inlet of the rotary intensified reactor into the rotary intensified reactor to form a suspension;

[0020] (2) spraying the suspension into the inner side of the wire mesh filler through a solution mixing distributor, and rotating the wire mesh filler driven by a motor to shear the suspension into small units;

[0021] (3) The micro-unit obtained in step (2) enters a crystallization kettle through the outlet of a rotary enhanced reactor for crystallization to obtain a crystallized material. The crystallized material is filtered, washed, dried, and then calcined to obtain the alumina carrier.

[0022] In the present invention, the preparation method of the carrier alumina is as follows Figure 1The schematic diagram of the rotary intensified impregnation equipment is shown. During the intensified hydrolysis process, the reaction liquid is dispersed into fine droplets and liquid films on the high-speed rotating screen, and the microenvironment of the precipitation reaction is more uniform, thereby obtaining crystal seeds of uniform size. After crystallization and calcination, a carrier alumina with stable structure and performance is obtained.

[0023] According to the present invention, preferably, the concentration of the aluminum sulfate solution is 0.5-2 mol / L.

[0024] According to the present invention, preferably, the aluminum hydroxide concentration in the aluminum hydroxide-sodium hydroxide mixed solution is 0.5-1 mol / L, and the sodium hydroxide concentration is 1-1.5 mol / L.

[0025] According to the present invention, preferably, the flow ratio of the aluminum sulfate solution to the aluminum hydroxide-sodium hydroxide mixed solution is 1:(0.5-2).

[0026] According to the present invention, preferably, in step (2), the wire mesh filler rotates at a speed of 2800 to 3200 rpm.

[0027] According to the present invention, preferably, in step (3), the crystallization conditions include: temperature of 60 to 100° C. and time of 2 to 24 h.

[0028] According to the present invention, preferably, the drying conditions include: a temperature of 60-120° C. and a time of 4-12 hours.

[0029] According to the present invention, preferably, the calcination conditions include: a temperature of 400-800° C. and a time of 4-8 hours.

[0030] According to the present invention, preferably, the alumina carrier has the following characteristics: a specific surface area of ​​300 to 800 m 2 / g, preferably 400 to 700 m 2 / g, and the average pore diameter is 10 to 40 nm, preferably 20 to 35 nm.

[0031] According to the present invention, preferably, the method for preparing the nickel catalyst comprises the following steps:

[0032] a) immersing the carrier alumina into a nickel salt solution by an excessive impregnation method to obtain a carrier alumina impregnated with a nickel salt solution;

[0033] b) directly drying and calcining the carrier alumina impregnated with the nickel salt solution obtained in step a) to obtain the nickel catalyst.

[0034] In the present invention, step a) only needs to be performed once, and the obtained carrier alumina impregnated with the nickel salt solution is directly dried and calcined to obtain the nickel catalyst.

[0035] According to the present invention, preferably, in step (a), the nickel salt solution is a water-soluble nickel salt solution, preferably at least one of a nickel nitrate solution, a nickel carbonate solution and a nickel sulfate solution.

[0036] According to the present invention, preferably, the concentration of the nickel salt solution is 3-5 mol / L, and the immersion time is 30-120 min.

[0037] According to the present invention, preferably, in step (b), the drying conditions include: a temperature of 110-130° C. and a drying time of 4-12 h.

[0038] According to the present invention, preferably, the calcination conditions include: a temperature of 600-800° C. and a time of 4-8 hours.

[0039] According to the present invention, preferably, based on the total weight of the nickel catalyst, the content of the active component nickel is 30-70wt%, preferably 40-60wt%, and the content of the carrier alumina is 30-70wt%, preferably 40-60wt%.

[0040] According to the present invention, preferably, the contact reaction conditions include: hydrogen pressure 1-10 MPa, reaction temperature 40-60°C.

[0041] The invention uses nickel components and alumina carriers commonly used in industry, has mild reaction conditions, high selectivity for isooctylaldehyde, and has certain industrial application prospects.

[0042] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0044] Figure 1 Schematic diagram of the rotary strengthening equipment.

[0045] Description of Reference Numerals

[0046] 1-1, aluminum sulfate solution; 1-2, aluminum hydroxide-sodium hydroxide mixture; 1-3, 1-4, liquid pump; 1-5, solution mixing distributor; 1-6, wire mesh filler; 1-7, rotating intensified reaction device housing; 1-8, reactant outlet; 1-9, crystallization kettle; 1-10, motor. DETAILED DESCRIPTION

[0047] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0048] The present invention will be further described below in conjunction with embodiments, but the scope of the present invention is not limited to these embodiments.

[0049] The test instruments and test conditions used in the examples are as follows:

[0050] The BET surface area and average pore size of the nickel catalyst were measured by N2 adsorption-desorption method.

[0051] The sources of raw materials used in the examples are as follows:

[0052] Other reagents used were commercially available and of analytical grade.

[0053] Example 1

[0054] Carrier alumina: Prepare 0.5 mol / L aluminum sulfate aqueous solution, aluminum hydroxide and sodium hydroxide are 1 mol / and 1 mol / respectively, the flow ratio of aluminum sulfate solution to aluminum hydroxide-sodium hydroxide mixed solution is 1:0.7, turn on the motor to drive the rotating filler, the speed is 3000 rpm, the two liquids are pumped into the liquid distributor through the horizontal flow pump, mixed and sprayed into the enhanced reactor, under the shearing action of the rotating filler, the mixed reaction liquid is sheared into tiny suspension droplets, and finally enters the crystallization kettle from the bottom of the enhanced reactor, and crystallizes at 80°C for 20 hours. After crystallization, it is filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder is calcined in an air atmosphere at 400°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method is 698m by the N2 adsorption and desorption method. 2 / g, and the average pore size is 21nm.

[0055] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120° C., and calcined at 400° C. to obtain a nickel catalyst with a NiO loading of 55%, which was recorded as A-1.

[0056] Example 2

[0057] Carrier alumina: Prepare 2 mol / L aluminum sulfate aqueous solution, aluminum hydroxide and sodium hydroxide mixed solution of 0.5 mol / and 1.5 mol / respectively, the flow ratio of aluminum sulfate solution to aluminum hydroxide-sodium hydroxide mixed solution is 1:2, turn on the motor to drive the rotating filler, the speed is 3000 rpm, the two liquids are pumped into the liquid distributor through the horizontal flow pump, mixed and sprayed into the enhanced reactor, under the shearing action of the rotating filler, the mixed reaction liquid is sheared into tiny suspension droplets, and finally enters the crystallization kettle from the bottom of the enhanced reactor, and crystallizes at 80°C for 20 hours. After crystallization, it is filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder is calcined in an air atmosphere at 500°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method is 412m by N2 adsorption and desorption method. 2 / g, and the average pore size is 32nm.

[0058] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120° C., and calcined at 400° C. to obtain a nickel catalyst with a NiO loading of 48%, which was recorded as A-2.

[0059] Example 3

[0060] Carrier alumina: Prepare 1 mol / L aluminum sulfate aqueous solution, aluminum hydroxide and sodium hydroxide mixed solution with 0.5 mol / and 1.5 mol / respectively, the flow ratio of aluminum sulfate solution to aluminum hydroxide-sodium hydroxide mixed solution is 1:1.2, turn on the motor to drive the rotating filler, the speed is 3000 rpm, the two liquids are pumped into the liquid distributor through the horizontal flow pump, mixed and sprayed into the enhanced reactor, under the shearing action of the rotating filler, the mixed reaction liquid is sheared into tiny suspension droplets, and finally enters the crystallization kettle from the bottom of the enhanced reactor, and crystallizes at 80°C for 20 hours. After crystallization, it is filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder is calcined in an air atmosphere at 800°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method is 581m by the N2 adsorption and desorption method. 2 / g, and the average pore size is 23nm.

[0061] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120° C., and calcined at 450° C. to obtain a nickel catalyst with a NiO loading of 51%, which was recorded as A-3.

[0062] Comparative Example 1

[0063] The carrier alumina was prepared by ordinary coprecipitation method: 1 mol / L aluminum sulfate aqueous solution, aluminum hydroxide and sodium hydroxide were mixed with 0.5 mol / and 1.5 mol / , respectively, and the flow ratio of aluminum sulfate solution to aluminum hydroxide-sodium hydroxide mixed solution was 1:1.2, and they were added dropwise into the stirred reactor. The reaction precipitate was transferred to the crystallization kettle for crystallization at 80°C for 20 hours. After crystallization, it was filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder was calcined in an air atmosphere at 500°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method was measured by N2 adsorption and desorption method to be 406m2 / g, and the average pore size was 13nm.

[0064] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120° C., and calcined at 450° C. A nickel catalyst with a NiO loading of 21% was obtained by one immersion, which was recorded as D-1.

[0065] In the comparative example, the alumina carrier prepared by ordinary stirring was used, the average pore size was reduced, and the loading amount in one impregnation was reduced.

[0066] Experimental Example 1

[0067] Comparison of isooctene aldehyde hydrogenation reaction performance:

[0068] The catalytic effect of the catalyst on the hydrogenation of isooctene aldehyde was evaluated by using a high-pressure reactor. The catalyst was reduced with pure hydrogen at 450°C for 4 hours before use. 2g of catalyst, 5g of isooctene aldehyde, and 45g of dioxane were added to a stainless steel reactor, which was completely sealed, and the air in the reactor was replaced with high-purity hydrogen three times. The reaction temperature was set at 50°C, the reaction pressure was 3 MPa, and the stirring rate was 200 rpm. The reaction was carried out for 5 hours, and the reaction product was detected by gas chromatography.

[0069] The catalysts A1-3 and D1 were evaluated according to the above evaluation method. Table 1 shows the reaction results.

[0070] Table 1

[0071]

[0072] As can be seen from Table 1, the structure of the carrier determines the performance of the catalyst. The carrier alumina prepared by the enhanced hydrolysis method has a more uniform structure, which increases the specific surface area and average pore size of alumina. Therefore, when impregnating the active component, the primary loading amount of the active component can be significantly increased, and the active component is more evenly dispersed, which significantly improves the selectivity of isooctylaldehyde. At the same time, the reaction temperature can be reduced, which meets the goal of energy saving and carbon reduction.

[0073] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0074] 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.

Claims

1. A method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde, characterized in that: isooctene aldehyde, hydrogen and a nickel catalyst are contacted and reacted, wherein the nickel catalyst comprises a carrier alumina and an active component nickel dispersed thereon; The carrier alumina is prepared by a rotary strengthening device, which includes a rotary strengthening reactor, at least two liquid pumps, a crystallization kettle and a motor; The rotary enhanced reactor comprises a rotary enhanced reaction device shell, a wire mesh filler and a solution mixing distributor, wherein the wire mesh filler is located inside the rotary enhanced reaction device shell, and a certain space is formed inside the wire mesh filler, the solution mixing distributor is placed in the space, and the motor is connected to the wire mesh filler; The liquid pump is provided with a liquid pump discharge pipeline, the rotary enhanced reaction device housing is provided with a rotary enhanced reactor inlet and a rotary enhanced reactor outlet, the liquid pump discharge pipeline is connected to the solution mixing distributor through the rotary enhanced reactor inlet, and the rotary enhanced reactor outlet is connected to the crystallization kettle; The steps include: (1) using a liquid pump to pump the aluminum sulfate solution and the aluminum hydroxide-sodium hydroxide mixed solution from the inlet of the rotary intensified reactor into the rotary intensified reactor to form a suspension; (2) spraying the suspension into the inner side of the wire mesh filler through a solution mixing distributor, and rotating the wire mesh filler driven by a motor to shear the suspension into small units; (3) The micro-unit obtained in step (2) enters a crystallization kettle through the outlet of a rotary enhanced reactor for crystallization to obtain a crystallized material. The crystallized material is filtered, washed, dried, and then calcined to obtain the alumina carrier.

2. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 1, wherein The concentration of the aluminum sulfate solution is 0.5-2 mol / L; The aluminum hydroxide-sodium hydroxide mixed solution has an aluminum hydroxide concentration of 0.5-1 mol / L and a sodium hydroxide concentration of 1-1.5 mol / L; The flow ratio of the aluminum sulfate solution to the aluminum hydroxide-sodium hydroxide mixed solution is 1:(0.5-2).

3. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 1, wherein, In step (2), the wire mesh filler rotates at a speed of 2800 to 3200 rpm.

4. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 1, wherein In step (3), the crystallization conditions include: temperature of 60 to 100° C. and time of 2 to 24 h; The drying conditions include: temperature of 60-120°C and time of 4-12h; The calcination conditions include: a temperature of 400-800° C. and a time of 4-8 hours.

5. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 1, wherein, The alumina carrier has the following characteristics: a specific surface area of ​​300 to 800 m 2 / g, preferably 400 to 700 m 2 / g, and the average pore diameter is 10 to 40 nm, preferably 20 to 35 nm.

6. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to any one of claims 1 to 5, wherein: The preparation method of the nickel catalyst comprises the following steps: a) immersing the carrier alumina into a nickel salt solution by an excessive impregnation method to obtain a carrier alumina impregnated with a nickel salt solution; b) directly drying and calcining the carrier alumina impregnated with the nickel salt solution obtained in step a) to obtain the nickel catalyst.

7. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 6, wherein In step (a), the nickel salt solution is a water-soluble nickel salt solution, preferably at least one of a nickel nitrate solution, a nickel carbonate solution and a nickel sulfate solution; The concentration of the nickel salt solution is 3-5 mol / L, and the immersion time is 30-120 min.

8. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 6, wherein, In step (b), the drying conditions include: a temperature of 110 to 130° C. and a time of 4 to 12 hours; The calcination conditions include: temperature of 600-800°C and time of 4-8h.

9. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 6, wherein Based on the total weight of the nickel catalyst, the content of the active component nickel is 30-70wt%, preferably 40-60wt%, and the content of the carrier alumina is 30-70wt%, preferably 40-60wt%.

10. The method for preparing isooctyl aldehyde by selective hydrogenation of isooctyl aldehyde according to claim 1, wherein: The conditions for the contact reaction include: hydrogen pressure of 1-10 MPa and reaction temperature of 40-60°C.

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