A process for the continuous reaction preparation of normal aldehydes

Abstract

The application provides a method for preparing normal aldehyde by continuous reaction, which comprises the following steps: S1, isomerization reaction of raw material non-conjugated allyl alcohol under the action of a first catalyst in a hydrogen atmosphere to obtain a first mixture; S2, hydrogenation reaction of the first mixture by adding a second catalyst to obtain a second mixture; and S3, purification of the second mixture by rectification to obtain the normal aldehyde. The second catalyst is directly added in the isomerization reaction to obtain the second mixture, and the normal aldehyde product with high purity can be obtained after separation and purification of the second mixture. In the isomerization reaction, the synergistic catalysis of the active component and the active adjuvant in the first catalyst avoids the generation of a series of by-products with similar structures and close boiling points, and high raw material conversion rate and high product selectivity are obtained.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and specifically to a method for preparing n-aldehydes by continuous reaction. Background Technology

[0002] n-Aldehydes are an important class of synthetic fragrances and key intermediates in the preparation of high-grade fragrances, bactericides, precious metal extractants, and surfactants. Taking n-octanal as an example, it is an important organic synthetic intermediate and fragrance, naturally found in citrus essential oils, possessing a strong, pungent fruity aroma. When diluted, it has an aroma reminiscent of unripe citrus and a pleasant sweet orange scent. n-Aldehydes offer a variety of aroma profiles and can be used as citrus flavorings in beverages and ice cream. Downstream products of n-octanal include n-octanol, n-octylamine, n-octanoic acid, hexylcinnamaldehyde, and dihydrojasmone, which are widely used in the production of plasticizers, bactericides, precious metal extractants, surfactants, and fragrances.

[0003] The currently disclosed synthesis processes for n-aldehydes (taking n-octaldehyde as an example) include the following:

[0004] I. Catalytic Oxidation of n-Octanol. For example, patent CN101733145A discloses a mesoporous molecular sieve catalyst supported on Ag for catalytic dehydrogenation of n-octanol to n-octanal. This process has a reaction temperature as high as 400℃ and a short catalyst lifetime; furthermore, the mass space velocity of the reaction is only 0.14 h⁻¹, which is difficult to meet industrial requirements. Patents CN100548473C and CN101293799A disclose Ru catalysts supported on alumina or carbon nanotubes for catalytic oxidation of n-octanol to n-octanal, but both technologies have low feed conversion rates and product selectivity. Patent CN106964404A discloses the use of a magnesium-aluminum layered double hydroxide catalyst supported on Fe / Co metal complexes for the catalytic oxidation of n-octanol with air. The catalyst preparation process of this process is very complex, and the catalytic efficiency is low, achieving only a 56% n-octanal yield, making it impractical from a commercial perspective.

[0005] II. 1-Heptene Hydroformylation Method. This process uses 1-heptene and a mixed gas to undergo hydroformylation under the catalysis of the precious metal rhodium, producing n-octanal and 2-methylheptal. The limitations of this process include two points: ① 1-Heptene is not readily available. In the 1950s, paraffin dehydrogenation was used to prepare α-olefins, but this method was too costly and has been phased out. At the same stage, South Africa accelerated the development of coal-to-oil technology, achieving production through this process, and 1-heptene can be obtained after distillation purification. Currently, there is no experience in the industrial-scale separation of α-olefins from Fischer-Tropsch synthesis products in China, and globally only Sasol Company in South Africa possesses this technology; ② The use of expensive rhodium catalysts requires heating the reaction mixture to high temperatures during rhodium recovery until high-boiling-point long-chain aldehyde products are distilled off. During this process, the rhodium catalyst is highly susceptible to pyrolysis, leading to the formation of rhodium clusters and metal precipitation, as well as catalyst degradation and oxidation, forming high-boiling-point compounds. This makes it difficult to recycle the catalyst for a sufficiently long period, resulting in a sharp increase in production costs.

[0006] III. Hydrogenation of 7-Octen-1-aldehyde. Patents EP0069339B1 and US4510331A disclose the process of producing n-octanal by hydrogenation of 7-octen-1-aldehyde using Pd or Ni catalysts. However, the process has the following problems: ① 7-Octen-1-aldehyde is produced by isomerization of 2,7-octadien-1-ol using a copper-chromium catalyst at 200-250℃. This reaction produces a variety of products, including 7-octen-1-aldehyde, cis / trans-6-octen-1-aldehyde, 2,7-octadien-1-aldehyde, n-octanal, 7-octen-1-ol, and n-octanol. These products must be separated and purified to obtain 7-octen-1-aldehyde with sufficiently high purity before it can be further used for hydrogenation to produce high-purity n-octanal. Otherwise, the impurities will seriously affect the purity of n-octanal. However, these byproducts generated by the isomerization reaction can form various byproducts such as acetals and internal double bond migrations at high temperatures, as well as high-boiling-point products. Furthermore, the molecular structures and boiling points of these products and byproducts are extremely similar, inevitably increasing the operational difficulty and purification cost of distilling and separating 7-octen-1-aldehyde. This also leads to the introduction of some impurities that are difficult to separate from n-octaldehyde during subsequent hydrogenation reactions. Secondly, during the research process of this invention's research team, it was discovered that during the isomerization of 2,7-octadien-1-ol to prepare 7-octen-1-aldehyde using a copper-chromium catalyst, the catalytic activity of the catalyst gradually decreases. The selectivity of 7-octen-1-aldehyde decreases, and the proportion of high-boiling-point products increases, which makes 7-octen-1-aldehyde extremely difficult to obtain. This further increases the raw material and purification costs for the preparation of n-octanal, reducing the product's technological competitiveness. ③ Hydrogenation of 7-octen-1-aldehyde as a raw material will produce a portion of n-octanol as a byproduct. The ratio of n-octanol to n-octanol is 69:31 to 72:28. Although the aldehyde and alcohol can be separated by subsequent distillation, the value of n-octanol is far lower than that of n-octanol. This is very detrimental to reducing the production cost of the equipment and improving technological competitiveness. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention discloses a method for preparing n-aldehydes through a continuous reaction. This method uses non-conjugated allyl alcohol as raw material and prepares n-aldehydes through continuous isomerization and hydrogenation reactions under the action of a first catalyst and a second catalyst, respectively. This method has high raw material conversion rate and product selectivity, and the product purity can reach over 99 wt%.

[0008] To achieve the above technical objectives, this invention proposes a method for the continuous reaction preparation of n-aldehydes, which includes the following steps:

[0009] S1, Under a hydrogen atmosphere, the non-conjugated allyl alcohol raw material undergoes an isomerization reaction in the presence of a first catalyst to obtain a first mixture.

[0010] S2, a second catalyst is added to the first mixture to carry out a hydrogenation reaction, and a second mixture is obtained;

[0011] S3, the second mixture is purified by distillation to obtain the n-aldehyde;

[0012] The first catalyst is a supported catalyst, comprising a main metal as the active component and a cooperating metal as an active agent. The main metal includes at least one of rhodium, ruthenium, palladium, platinum, and iridium. The cooperating metal includes at least one of cerium, lanthanum, praseodymium, zinc, manganese, cobalt, and nickel. The second catalyst is a supported catalyst whose active component includes at least one of rhodium, ruthenium, palladium, platinum, nickel, and cobalt, or at least one selected from Raney nickel and Raney cobalt catalysts.

[0013] Based on exploratory experiments, the research team of this invention discovered that the active components and active promoters contained in the first catalyst exhibited a high synergistic catalytic effect in the catalytic isomerization reaction of non-conjugated allyl alcohols. The promoter metal, acting as an active promoter, not only improves the dispersibility of the main metal in the catalyst and reduces its particle size, but also effectively controls the double bond migration ability and hydrogenation activity of the main metal through electronic interactions. This preferentially promotes the isomerization of allyl alcohol groups in the feedstock and inhibits the migration of double bonds to other positions and the hydrogenation of double bonds, thereby avoiding the generation of a series of structurally similar byproducts with similar boiling points during the continuous dehydrogenation and hydrogenation process in existing technologies using copper-chromium catalysts for this type of reaction. The embodiments and comparative examples of this invention explore the technical effects of a first catalyst containing different main metals and promoter metals in the catalytic preparation of n-aldehydes.

[0014] In the above technical solution, by using the supported catalyst described in this invention to catalyze the isomerization reaction, a higher proportion of allyl alcohol isomerization products and a very small proportion of double bond migration byproducts can be obtained. Therefore, subsequent hydrogenation reactions can be carried out directly without separation and purification. Combined with the use of a second catalyst for catalytic hydrogenation, high-yield and high-purity n-aldehyde products can be obtained. The continuous reaction method used in this invention to prepare n-aldehydes is highly beneficial for simplifying distillation and purification operations, reducing energy consumption, optimizing the production process, improving production technology, and enabling large-scale industrial production.

[0015] It should be noted that the second catalyst in the above technical solution is a commonly used hydrogenation catalyst, including a catalyst supported by an active component containing at least one element selected from rhodium, ruthenium, palladium, platinum, nickel, and cobalt, or at least one selected from Raney nickel and Raney cobalt catalysts.

[0016] In a further example of the present invention, the ratio of the active component, support, and active auxiliaries in the first catalyst was explored. Optionally, the mass ratio of the active component to the support in the first catalyst is (0.001-0.05):1, more preferably (0.003-0.03):1; optionally, the mass ratio of the active auxiliaries to the active component is (0.001-1):1, more preferably (0.05-0.5):1. This can improve the synergistic catalytic effect of the active component and the active auxiliaries, and increase the conversion rate of raw materials and the selectivity of n-aldehydes in specific preparation reactions.

[0017] It should be noted that, in the optional examples of the present invention, the support for the first catalyst may be at least one of alumina, activated carbon, silicon dioxide, titanium dioxide, zirconium oxide, molecular sieve, hydrotalcite, and kaolin, and may further be at least one of γ-alumina, silicon dioxide, and zirconium oxide. Those skilled in the art can select other supports based on the present invention through non-creative labor, and the resulting technical solutions are all within the protection scope of the present invention. It should also be noted that the structure of the molecular sieve is not limited in the present invention, and ZSM-5 type or Y-type molecular sieve may be selected. Those skilled in the art can select other supports based on the present invention through non-creative labor, and the resulting technical solutions are all within the protection scope of the present invention.

[0018] In a further example of the invention, the amounts of the non-conjugated allyl alcohol and the catalyst used in the isomerization reaction were explored. Optionally, the mass hourly space velocity of the raw material in step S1 is 0.1 to 20 g / g / h, preferably 0.5 to 10 g / g / h, and more preferably 0.6 to 5 g / g / h.

[0019] In a further example of the invention, the control conditions of the isomerization reaction were explored. Optionally, the temperature of the isomerization reaction is 50–120°C, preferably 60–100°C; the reaction pressure is 0–1 MPa, preferably 0.1–0.5 MPa. The isomerization reaction of the present invention employs relatively low reaction temperature and pressure, which on the one hand facilitates the regulation of double bond migration ability of the supported catalyst, preferentially promoting the isomerization of allyl alcohol groups in the raw materials, reducing the migration of double bonds to other positions and the formation of byproducts from saturated hydrogenation; on the other hand, it allows the reaction to proceed under milder conditions, preventing the generated aldehyde from rapidly coking or forming high-boiling-point byproducts such as acetals due to high temperatures, thus preventing rapid catalyst deactivation. In a further optional example of the present invention, the isomerization reaction apparatus equipped with the first catalyst can operate continuously for more than 1000 hours without catalyst deactivation. Therefore, by controlling the isomerization reaction conditions, the present invention can significantly reduce the cost of catalyst use while improving the conversion rate of raw materials and the selectivity of products, thereby enhancing the technical competitiveness of the method and facilitating cost control in industrial production.

[0020] It should be noted that the isomerization reaction of the present invention can be carried out by batch method or continuous method, and more preferably by continuous method. Those skilled in the art can select the appropriate operation mode according to the actual working conditions, and the resulting technical solutions are all within the protection scope of the present invention.

[0021] It should be noted that in the technical solution of the present invention, the first mixture obtained by the isomerization reaction does not need to be separated into products or catalysts, and a second catalyst can be directly added to carry out selective hydrogenation reaction. Thus, the n-aldehyde is prepared through continuous reaction, which simplifies the process, reduces energy consumption, and improves operability and production efficiency. This has important advantages in large-scale industrial production.

[0022] In a further example of the present invention, the temperature of the hydrogenation reaction is 50-120°C, preferably 60-100°C; the reaction pressure is 0-1 MPa, preferably 0.1-0.5 MPa. Compared with the isomerization reaction, the hydrogenation reaction also uses a lower reaction temperature and reaction pressure, which is beneficial to maintaining the beneficial effects of the isomerization reaction control conditions and ensuring the advantages of catalyst activity and raw material conversion rate in the overall continuous reaction preparation of n-aldehydes.

[0023] In a further example of the invention, the amount of hydrogen introduced into the hydrogen-containing atmosphere and the composition of the hydrogen atmosphere were explored. Optionally, the molar ratio of hydrogen to raw material in the hydrogen-containing atmosphere is 1.5:1 to 10:1, more preferably 2:1 to 6:1. Optionally, the hydrogen-containing atmosphere in step S1 is a pure hydrogen atmosphere or a hydrogen atmosphere containing an inert gas. Through exploratory experiments, the research team of this invention unexpectedly discovered that the catalytic activity of the first catalyst can be controlled by adjusting the proportion of hydrogen in the hydrogen-containing atmosphere. Further, optionally, when the hydrogen-containing atmosphere is a hydrogen atmosphere containing an inert gas, the volume ratio of hydrogen to inert gas is 99:1 to 1:99, more preferably 95:5 to 50:50, thereby achieving a balance between its double bond migration ability and hydrogenation ability. Combined with the catalyst's unique main metal and auxiliary metal composition, it can effectively suppress the migration of double bonds in the feedstock to other positions and the formation of saturated hydrogenation byproducts, thereby maximizing the synergistic effect of the catalyst's active components and active promoters, improving product selectivity and yield. Furthermore, it reduces the difficulty of subsequent product separation and distillation energy consumption.

[0024] It should be noted that the inert gas mentioned in this invention refers to a gas that does not chemically interact with the reactants, such as nitrogen and gases of Group 0 elements in the periodic table (such as argon).

[0025] The continuous reaction method for preparing n-aldehydes of this invention has broad applicability and can be used to prepare n-aldehydes with various carbon atom numbers. In a further example of this invention, the non-conjugated allyl alcohol may be selected as a non-conjugated allyl alcohol having a carbon-carbon double bond alkenyl group and an allyl alcohol group at the other end of the molecule; further optionally, the non-conjugated allyl alcohol has 6 to 12 carbon atoms; in some optional examples of this invention, the non-conjugated allyl alcohol includes at least one of 2,5-hexadien-1-ol, 2,6-heptadien-1-ol, 2,7-octadien-1-ol, 2,8-nonadien-1-ol, 2,9-decadien-1-ol, 2,10-undecadien-1-ol, and 2,11-dodecadien-1-ol. The embodiments of this invention illustrate the process of preparing corresponding n-aldehydes from different non-conjugated allyl alcohol raw materials.

[0026] It should be noted that in the technical solution of this invention, the equipment for the isomerization reaction and hydrogenation reaction can be a fixed bed reactor, a reaction vessel, a slurry bed reactor, a circulating reactor, etc. Those skilled in the art can select suitable equipment through non-creative labor, and the resulting technical solutions are all within the protection scope of this invention.

[0027] It should be noted that in the continuous reaction method for preparing n-aldehydes of the present invention, the second mixture includes n-aldehyde and n-alcohol. Through extensive experimental verification, the research team has determined that the ratio of n-aldehyde to n-alcohol in the second mixture can be selected as 5–99:1, further selected as 10–99:1, and even further selected as 16–88:1. Furthermore, the purity of the n-aldehyde obtained by the present invention is not less than 99%. Taking the preparation of n-octaldehyde by the method of the present invention as an example, the obtained n-octaldehyde can be oxidized to n-octanoic acid, which can be commercially used as a starting material for the production of lubricants, drying agents, etc.; it can be converted to n-octylamine through reaction with ammonia and hydrogen, used for the production of precious metal extractants, surfactants, etc.; it can also react with benzaldehyde to produce hexylcinnamaldehyde and other fragrances and flavorings. High-purity products can be directly used in subsequent processes.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention directly adds a second catalyst to the first mixture obtained by the isomerization reaction to carry out a hydrogenation reaction, and the resulting second mixture can be separated and purified to obtain a high-purity n-aldehyde product; in the isomerization reaction, the synergistic catalysis of the active component and the active auxiliary agent in the first catalyst avoids the generation of a series of by-products with similar structures and similar boiling points in the isomerization reaction, thereby obtaining a high raw material conversion rate and a high product selectivity. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 The flowchart of the continuous reaction for preparing n-aldehydes in Example 1 is shown;

[0031] Figure 2 A scanning electron microscope image of the first catalyst A prepared in Catalyst Preparation Example 1 is shown;

[0032] Figure 3 The image shown is a scanning electron microscope (SEM) image of the first catalyst H prepared in Comparative Example 1. Detailed Implementation

[0033] To facilitate understanding of the present invention, a more comprehensive description will be provided below, along with preferred embodiments. However, it should be understood that these embodiments are merely for more detailed explanation and should not be construed as limiting the invention in any way, i.e., not intended to limit the scope of protection of the invention.

[0034] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0035] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0036] It should be noted that although the various steps of the preparation method of the present invention are described in a specific order in the description of the present invention, these orders are not restrictive. Without departing from the basic principles of the present invention, those skilled in the art can perform the steps in different orders.

[0037] The first catalyst used in the embodiments of the present invention may be prepared by the following method:

[0038] (1) Dissolve the soluble salt of the main metal or its complex in pure water at a mass ratio of main metal to carrier of (0.001-0.05):1, and heat to 30-100℃.

[0039] (2) The catalyst support is immersed in a solution of the main metal soluble salt or its complex for 0.5-24 hours for adsorption. Note that during the specific catalyst preparation process, the concentration of metal ions in the water can be determined by ICP ion chromatography to determine whether the adsorption is complete.

[0040] (3) After washing the catalyst support adsorbed with the main metal soluble salt or its complex three times with pure water, calcine it in air at 100-500℃ for 0.5-5 hours.

[0041] (4) Take a soluble salt of the auxiliary metal in a mass ratio of (0.001-1):1 to the main metal, dissolve it in pure water, and heat the resulting aqueous solution to 30-100℃.

[0042] (5) Add the catalyst support obtained in step (4) into the aqueous solution of the auxiliary metal salt obtained in step (4) for immersion and adsorption for 0.5-24 hours.

[0043] (6) The carrier obtained in step (5) that simultaneously adsorbs the main metal and the metal additive is washed three times with pure water and then calcined at 100-500℃ for 0.5-5 hours.

[0044] (7) The catalyst obtained in step (6) is reduced in a hydrogen atmosphere at a temperature of 30-300°C for 0.5-24 hours to obtain the first catalyst.

[0045] Using the above method, the following first catalyst was prepared in the embodiments of the present invention:

[0046] Catalyst preparation example 1: First catalyst A (0.8% Rh-0.3% Pr / SiO2)

[0047] 2.25 g of rhodium nitrate (0.8 g rhodium content) was dissolved in 100 mL of purified water, heated to 35 °C, and 100 g of SiO2 support (20-40 mesh) was added to the solution. The mixture was impregnated and adsorbed for 24 hours. After washing three times with purified water, it was calcined at 500 °C for 4 hours. 0.69 g of praseodymium nitrate (0.3 g praseodymium content) containing the active additive praseodymium was dissolved in 100 mL of purified water, heated to 40 °C, and the calcined and cooled rhodium-containing SiO2 support was again impregnated and adsorbed for 3 hours. After washing three times with purified water, it was calcined at 300 °C for 3 hours. The resulting catalyst support was reduced at 80 °C for 10 hours under a hydrogen atmosphere to obtain the first catalyst A. The electron microscopy results of the first catalyst A are shown below. Figure 2 As shown.

[0048] Catalyst preparation example 2: First catalyst B (0.5% Ru-0.025% Ce / γ-Al2O3)

[0049] 1.03 g of ruthenium trichloride (0.50 g ruthenium content) was dissolved in 100 mL of purified water, and the solution was heated to 80 °C. 100 g of γ-Al₂O₃ support (10-30 mesh) was added to the solution, and the mixture was impregnated for adsorption for 3 hours. After washing three times with purified water, the solution was calcined at 400 °C for 3 hours. 0.06 g of cerium nitrate (0.025 g cerium content) containing the active additive cerium was dissolved in 100 mL of purified water, and the solution was heated to 95 °C. The calcined and cooled ruthenium-containing support was again impregnated for adsorption for 0.5 hours. After washing three times with purified water, the solution was calcined at 400 °C for 5 hours. The resulting catalyst support was reduced at 100 °C for 8 hours under a hydrogen atmosphere to obtain the first catalyst B.

[0050] Catalyst preparation example 3: First catalyst C (1% Pt-0.5% La / ZrO2)

[0051] 2.63 g of chloroplatinic acid (platinum content 1.0 g) was dissolved in 100 mL of purified water, heated to 50 °C, and 100 g of ZrO2 (18-20 mesh) was added. The mixture was impregnated and adsorbed for 8 hours, washed three times with purified water, and then calcined at 350 °C for 5 hours. 1.17 g of lanthanum nitrate (lanthanum content 0.5 g) containing the active additive lanthanum was dissolved in 100 mL of purified water, heated to 75 °C, and the calcined and cooled platinum-containing support was again impregnated and adsorbed for 8 hours. After washing three times with purified water, the support was calcined at 350 °C for 3 hours. The resulting catalyst support was reduced at 60 °C for 24 hours under a hydrogen atmosphere to obtain the first catalyst C.

[0052] Catalyst preparation example 4: First catalyst D (3% Pd-0.24% Zn / activated carbon)

[0053] 0.22 g of palladium nitrate (3 g palladium content) was dissolved in 100 mL of purified water, and the solution was heated to 60 °C. 100 g of activated carbon support (80-100 mesh) was added to the solution, and the mixture was impregnated for adsorption for 1 hour. After washing three times with purified water, the solution was calcined at 300 °C for 3 hours. 0.70 g of zinc nitrate (0.24 g zinc content) containing the active agent zinc was dissolved in 100 mL of purified water, and the solution was heated to 80 °C. The palladium-containing support, after calcination and cooling, was again impregnated for adsorption for 1 hour. After washing three times with purified water, the solution was calcined at 450 °C for 4 hours. The resulting catalyst support was reduced at 90 °C for 8 hours under a hydrogen atmosphere to obtain the first catalyst D.

[0054] Catalyst preparation example 5: First catalyst E (0.1% Ir-0.05% Mn / TiO2)

[0055] 0.16 g of iridium trichloride (iridium content 0.1 g) was dissolved in 100 mL of purified water, and the solution was heated to 80 °C. 100 g of TiO2 support (80-100 mesh) was added to the solution, and the mixture was impregnated for adsorption for 0.5 hours. After washing three times with purified water, the solution was calcined at 350 °C for 5 hours. 0.16 g of manganese nitrate (manganese content 0.05 g) containing the active additive metallic manganese was dissolved in 100 mL of purified water, and the solution was heated to 60 °C. The calcined and cooled iridium-containing support was again impregnated for adsorption for 5 hours. After washing three times with purified water, the solution was calcined at 500 °C for 2 hours. The resulting catalyst support was reduced at 150 °C for 5 hours under a hydrogen atmosphere to obtain the first catalyst E.

[0056] Catalyst Preparation Example 6: First Catalyst F (5% Ru - 3% Co / molecular sieve)

[0057] 10.26 g of ruthenium trichloride (5 g ruthenium content) was dissolved in 100 mL of purified water, and the solution was heated to 30 °C. 100 g of molecular sieve support (40-60 mesh) was added to the solution, and the mixture was impregnated for adsorption for 10 hours. After washing three times with purified water, the solution was calcined at 500 °C for 3 hours. 9.31 g of cobalt nitrate (3 g cobalt content) containing the active additive cobalt was dissolved in 100 mL of purified water, and the solution was heated to 35 °C. The calcined and cooled ruthenium-containing support was again impregnated for adsorption for 24 hours. After washing three times with purified water, the solution was calcined at 350 °C for 5 hours. The resulting catalyst support was reduced at 200 °C for 5 hours under a hydrogen atmosphere to obtain the first catalyst F.

[0058] Catalyst Preparation Example 7: First Catalyst G (2% Rh-0.5% Ni / hydrotalcite)

[0059] 5.62 g of rhodium nitrate (0.8 g rhodium content) was dissolved in 100 mL of purified water, and the solution was heated to 35 °C. 100 g of hydrotalcite support (20-40 mesh) was added to the solution, and the mixture was impregnated for adsorption for 24 hours. After washing three times with purified water, the solution was calcined at 500 °C for 4 hours. 1.56 g of nickel nitrate (0.5 g nickel content) containing the active additive metallic nickel was dissolved in 100 mL of purified water, and the solution was heated to 50 °C. The calcined and cooled rhenium-containing support was again impregnated for adsorption for 2 hours. After washing three times with purified water, the solution was calcined at 450 °C for 5 hours. The resulting catalyst support was reduced at 120 °C for 5 hours under a hydrogen atmosphere to obtain the first catalyst G.

[0060] Catalyst preparation Comparative Example 1: First catalyst H (0.8% Rh / SiO2)

[0061] No auxiliary metal was added; only rhodium was added. The rest of the preparation process was the same as in Catalyst Preparation Example 1.

[0062] 2.25 g of rhodium nitrate (rhodium content 0.8 g) was dissolved in 100 mL of purified water, and the solution was heated to 35 °C. 100 g of SiO2 support (20-40 mesh) was added to the solution, and the mixture was impregnated and adsorbed for 24 hours. After washing three times with purified water, the solution was calcined at 500 °C for 4 hours. The resulting catalyst was then reduced at 80 °C for 10 hours under a hydrogen atmosphere to obtain catalyst H. The electron microscopy results of catalyst H are shown below. Figure 3 As shown. By comparison Figure 2 and Figure 3 It can be seen that adding a promoter metal as an active agent during catalyst preparation can improve the dispersibility of the main metal in the catalyst and reduce the particle size of the main metal.

[0063] Catalyst preparation Comparative Example 2: First catalyst I (0.3% Pr / SiO2)

[0064] No rhodium, the main metal, was added; only cerium, the auxiliary metal, was added. The rest of the preparation process was the same as in Catalyst Preparation Example 1.

[0065] 0.69 g of praseodymium nitrate (praseodymium content 0.3 g) containing the active additive praseodymium was dissolved in 100 mL of purified water. The solution was heated to 40 °C, and 100 g of SiO2 support (20-40 mesh) was added to the solution. The mixture was impregnated and adsorbed for 3 hours. After washing three times with purified water, the solution was calcined at 300 °C for 3 hours. The resulting catalyst support was then reduced at 80 °C for 10 hours under a hydrogen atmosphere to obtain catalyst I.

[0066] It should be noted that the preparation method of the first catalyst in the embodiments of the present invention does not limit the scope of protection of the present invention. Those skilled in the art can choose the loading order of the main metal and the auxiliary metal as needed. For example, it can also be selected to impregnate the loading carrier with a mixed salt solution or complex of the main metal and the auxiliary metal, or to first impregnate the carrier with the loading auxiliary metal salt solution or complex, and then impregnate it with the loading main metal salt solution or complex. All technical solutions formed thereby are within the scope of protection of the present invention.

[0067] In the following examples and comparative examples, the first catalyst AG and the first catalyst HI will be used for the preparation of n-aldehydes.

[0068] It should be noted that in the following examples and comparative examples, gas chromatography will be used to analyze the components in the reaction system, and quantification will be performed using the correction and normalization method. These methods can be performed according to existing techniques. Based on this, the conversion rate of the reactants, the selectivity of the products, and the yield will be calculated. The gas chromatography analysis conditions are as follows:

[0069] Chromatographic column: Agilent DB-Wax (30m×0.32mm×0.25mm); Injector temperature: 300℃; Split ratio: 30:1; Column flow rate: 1.5mL / min; Column temperature: 100℃ for 0.5min; Temperature program: 15℃ / min to 300℃, hold for 8min; Detector temperature: 300℃; Hydrogen flow rate: 35mL / min; Air flow rate: 350mL / min.

[0070] Example 1

[0071] Step S1: The first catalyst A is filled into an isomerization reactor (fixed-bed reactor) equipped with a heating and insulation device. The reactor tube diameter is 20 mm, the tube length is 2000 mm, and the catalyst filling height is 200 mm. Before the reaction, the reactor is purged three times with nitrogen. After the reaction starts, hydrogen and nitrogen are introduced from the top of the reactor under the control of gas flow meters. At the same time, the feedstock 2,7-octadien-1-ol is pumped into the preheater via a plunger pump and a pipeline with heating, and the preheating temperature is 50°C. Then, the feedstock is mixed with the nitrogen-hydrogen mixture and introduced into the fixed-bed reactor in a co-current flow from the top of the reactor. The hydrogen flow rate is controlled so that the molar ratio of feedstock 2,7-octadien-1-ol to hydrogen is 1:2, and the volumetric flow rate ratio of hydrogen to nitrogen is 20:80. The reaction bed temperature is controlled at 80°C, the system pressure is controlled at 0.15 MPa, and the residence time is controlled by the mass hourly space velocity, i.e., controlled at 1.0 g feedstock / g catalytic active metal / hour. The equipment runs continuously for 48 hours, and the reaction liquid is collected from the bottom of the reactor. After multi-stage cooling, the first mixture of products is obtained.

[0072] Step S2: A second catalyst of 0.5% Pd / γ-Al2O3 is filled into a hydrogenation reactor (fixed-bed reactor) equipped with a heating and insulation device. The reactor tube diameter is 20 mm, the tube length is 2000 mm, and the catalyst filling height is 200 mm. Before the reaction, the reactor is purged three times with nitrogen. After the reaction begins, hydrogen is introduced from the top of the reactor under the control of a gas flow meter. Simultaneously, the first mixture obtained in step S1 is directly pumped into the preheater via a plunger pump and a pipeline with heating. The preheating temperature is 80°C. Then, the material is mixed with hydrogen and introduced into the fixed-bed hydrogenation reactor in a co-current flow from the top of the reactor. The hydrogen flow rate is controlled so that the molar ratio of the first mixture obtained in step S1 to hydrogen is 1:1.5. The reaction bed temperature is controlled at 90°C, the system pressure is controlled at 0.5 MPa, and the residence time is controlled by the mass hourly space velocity (MSV), i.e., 0.8 g feed / g catalytic active metal / hour. The equipment runs continuously for 48 hours. The reaction liquid is collected from the bottom of the reactor and, after multi-stage cooling, the second mixture of products is obtained. After gas chromatography detection and quantification using the correction and normalization method, the conversion rate of the raw material 2,7-octadien-1-ol was 98.8%, the selectivity of the product n-octanal was 96.5%, the selectivity of n-octanol was 2.6%, the ratio of n-octanal to n-octanol was 37:1, and the selectivity of other components and high-boiling products totaled 0.9%.

[0073] Step S3: Take 500g of the second mixture obtained in Step S2 and place it in the reboiler of a distillation column for distillation purification (the distillation column is 1.5m high, 30cm inner diameter, and filled with 1.2m of Westerley ring packing). Control the vacuum degree of the distillation column at 0.5kPaA, the reboiler temperature at 65-90℃, and the top temperature at 25-45℃. Within this top temperature range, 482.5g of n-octanal with a purity of over 99% can be obtained. Continue the distillation operation, with the reboiler temperature at 90-105℃ and the top temperature at 48-55℃. Within this top temperature range, 11.8g of n-octanol with a purity of over 99% can be obtained. 4.5g of high-boiling-point heavy components remain in the reboiler, and 4.2g of light components are lost. The total distillation yield of n-octanal and n-octanol is 98.86%.

[0074] Examples 2-8

[0075] Step S1: First catalysts A through G are respectively filled into an isomerization reactor (fixed-bed reactor) equipped with a heating and insulation device. The reactor tube diameter is 20 mm, the tube length is 2000 mm, and the catalyst filling height is 200 mm. Before the reaction, the reactor is purged three times with nitrogen. After the reaction begins, hydrogen and nitrogen are introduced from the top of the reactor under the control of gas flow meters. Simultaneously, the feedstock 2,7-octadien-1-ol is pumped into the preheater via a plunger pump and a heated pipeline, with a preheating temperature of 60°C. Then, the feedstock is mixed with the nitrogen-hydrogen mixture and introduced into the fixed-bed reactor in a co-current flow from the top of the reactor. The hydrogen flow rate is controlled so that the molar ratio of the feedstock 2,7-octadien-1-ol to hydrogen is 1:1.5 to 1:5, and the volumetric flow rate ratio of hydrogen to nitrogen is 95:5 to 50:50. The reaction bed temperature was controlled at 50–100℃, the system pressure at 0.1–0.5 MPa, and the residence time was controlled by the mass hourly space velocity (MSV), i.e., 0.5–2.5 g feed / g catalytically active metal / hour. The equipment was run continuously for 48 hours. The reaction liquid was collected from the bottom of the reactor and, after multi-stage cooling, the first mixture of products was obtained.

[0076] Step S2: The second catalysts 0.8% Pd / γ-Al2O3, 0.5% Pt / γ-Al2O3, 0.8% Rh / SiO2, 3% Ru / activated carbon, 2% Ni / γ-Al2O3, 1% Co / SiO2, and Raney Ni are respectively packed into a hydrogenation reactor (fixed-bed reactor) equipped with a heating and insulation device. The reactor tube diameter is 20 mm, the tube length is 2000 mm, and the catalyst packing height is 200 mm. Before the reaction, the reactor is purged three times with nitrogen. After the reaction starts, hydrogen is introduced from the top of the reactor under the control of a gas flow meter. Simultaneously, the first mixture obtained in step S1 is directly pumped into the preheater via a plunger pump and a pipeline with heating, preheating the temperature to 80°C. Then, the material is mixed with hydrogen and introduced into the fixed-bed hydrogenation reactor in a co-current flow from the top of the reactor. The hydrogen flow rate is controlled so that the molar ratio of the first mixture obtained in step S1 to hydrogen is 1:1.5. The reaction bed temperature was controlled at 60–120℃, the system pressure at 0.5–5 MPa, and the residence time was controlled by the mass hourly space velocity (MSV), i.e., 0.5–3 g feed / g catalytically active metal / hour. The equipment operated continuously for 48 hours. The reaction liquid was collected from the bottom of the reactor and, after multi-stage cooling, a second mixture of products was obtained. The reaction results, obtained by gas chromatography and quantification using a correction-normalization method, are shown in Table 1. The purity of the prepared n-aldehyde was subsequently tested, and the results are also shown in Table 1.

[0077] Example 9

[0078] The parameters and control conditions in this embodiment are the same as those in Example 2, except that the second catalyst 0.8% Pd / γ-Al2O3 used in Example 1 is replaced with 0.8% Rh / SiO2. The reaction results are shown in Table 1.

[0079] Comparative Example 1

[0080] The parameters and control conditions of this comparative example are the same as those of Example 1, except that the first catalyst A used in Example 1 is replaced with catalyst H. The reaction results are shown in Table 1.

[0081] Comparative Example 2:

[0082] The parameters and control conditions for this comparative example are the same as those for Example 1, except that the first catalyst A used in Example 1 is replaced with catalyst I. The reaction results are shown in Table 1.

[0083] Comparative Example 3:

[0084] The parameters and control conditions of this comparative example are the same as those of Example 3, except that the hydrogen-nitrogen ratio of the isomerization reaction in step S1 is adjusted from 25:75 to 99.9:0.1. The reaction results are shown in Table 1.

[0085] Comparative Example 4:

[0086] The parameters and control conditions of this comparative example are the same as those of Example 3, except that the hydrogen-nitrogen ratio of the isomerization reaction in step S1 is adjusted from 25:75 to 0.1:99.9. The reaction results are shown in Table 1.

[0087] Comparative Example 5:

[0088] The parameters and control conditions of this comparative example are the same as those of Example 1, except that the first mixture of products obtained in step S1 of Example 1 is separated by distillation and purified to obtain 450g of 7-octenal with a purity of 99.8%. The obtained 7-octenal is then subjected to step S2. The reaction results are shown in Table 1.

[0089] Comparative Example 6:

[0090] The parameters and control conditions of this comparative example are the same as those of Example 1, except that the temperature of the isomerization reaction in step S1 of Example 1 is adjusted from 80°C to 150°C. The reaction results are shown in Table 1.

[0091] Comparative Example 7:

[0092] The parameters and control conditions of this comparative example are the same as those of Example 1, except that the temperature of the isomerization reaction in step S1 of Example 1 was adjusted from 80°C to 35°C. The reaction results are shown in Table 1.

[0093]

[0094] As shown in Table 1, compared to the first catalyst in the examples that includes both active components and active additives, the comparative example using only one metal catalyst under the same reaction conditions yielded very low selectivity for n-octanal, with n-octanol or double bond migration byproducts being the main products. The active components and active additives of the first catalyst in this embodiment exhibited high synergistic catalytic activity in the isomerization reaction of 2,7-octadien-1-ol. The addition of the active additive effectively controlled the double bond migration ability and hydrogenation activity of the host metal, thereby regulating the host metal to preferentially promote the isomerization of allyl alcohol groups in the feedstock, inhibiting the migration of double bonds to other positions and the hydrogenation of double bonds, thus avoiding a series of structurally similar and boiling-point-similar byproducts found in the prior art. In this embodiment, after the isomerization reaction and selective hydrogenation reaction, almost only n-octanal and n-octanol were generated, with high selectivity for n-octanal (16–44:1 ratio). The selectivity for other double bond migration and high-boiling-point products was almost 1%, all of which are superior to existing technologies.

[0095] Furthermore, the relatively mild reaction conditions in the embodiments of the present invention, along with the optimization of the catalytic activity of the first catalyst by adjusting the ratio of hydrogen to inert gas in a hydrogen-containing atmosphere, achieve a balance between its double bond migration ability and hydrogenation ability (in Comparative Examples 3-4: under pure hydrogen or pure nitrogen conditions, the double bond migration byproducts and saturated hydrogenation byproducts significantly increased). Combined with the properties and characteristics of the catalyst itself, multiple means and mechanisms were used to jointly regulate the catalyst activity, maximizing the synergistic effect, improving product selectivity, avoiding the generation of byproducts with similar functional groups and carbon atom numbers, and greatly reducing the difficulty of product separation, operational difficulty, and subsequent distillation energy consumption.

[0096] Examples 9-14

[0097] Step S1: As shown in Table 2, in Examples 9-14, the first catalysts A-F were respectively filled into isomerization reactors (fixed-bed reactors) equipped with heating and insulation devices. The reactor tube diameter was 20 mm, the tube length was 2000 mm, and the catalyst filling height was 200 mm. Before the reaction, the reactor was purged with nitrogen three times. After the reaction started, hydrogen and nitrogen were introduced from the top of the reactor under the control of gas flow meters. At the same time, non-conjugated allyl alcohol raw materials with carbon-carbon double bonds at the end of the alkenyl and allyl groups (6-12 carbon atoms) were pumped into the preheater by a plunger pump through a pipeline with heating. The preheating temperature was 60°C. Then, the material was mixed with the nitrogen-hydrogen mixture and introduced into the fixed-bed reactor in parallel from the top of the reactor. The hydrogen flow rate was controlled so that the molar ratio of the raw material 2,7-octadien-1-ol to hydrogen was 1:1.5, and the volumetric flow rate ratio of hydrogen to nitrogen was 20:80. The reaction bed temperature was controlled at 50–100℃, the system pressure at 0.1–0.5 MPa, and the residence time was controlled by the mass hourly space velocity (MSV), i.e., 1.0 g feed / g catalytically active metal / hour. The equipment operated continuously for 48 hours, and the reaction liquid was collected from the bottom of the reactor. After multi-stage cooling, the first mixture was obtained.

[0098] Step S2: 0.5% Pt / γ-Al2O3 hydrogenation catalyst is filled into a hydrogenation reactor (fixed-bed reactor) equipped with a heating and insulation device. The reactor tube diameter is 20 mm, the tube length is 2000 mm, and the catalyst filling height is 200 mm. Before the reaction, the reactor is purged three times with nitrogen. After the reaction begins, hydrogen is introduced from the top of the reactor under the control of a gas flow meter. Simultaneously, the first mixture obtained in step S1 is directly pumped into the preheater via a plunger pump and a pipeline with heating, preheating the temperature to 80°C. Then, the material is mixed with hydrogen and introduced into the fixed-bed hydrogenation reactor in a co-current flow from the top of the reactor. The hydrogen flow rate is controlled so that the molar ratio of the first mixture obtained in step S1 to hydrogen is 1:1.5. The reaction bed temperature is controlled at 80°C, the system pressure is controlled at 0.5 MPa, and the residence time is controlled by the mass hourly space velocity (MSV), i.e., controlled at 1.0 g feed / g catalytic active metal / hour. The equipment runs continuously for 48 hours. The reaction liquid is collected from the bottom of the reactor and, after multi-stage cooling, the second mixture is obtained. The reaction results, after being detected by gas chromatography and quantified by the calibration normalization method, are shown in Table 2.

[0099] Table 2 Reaction results of Examples 9-14

[0100]

[0101] Example 15

[0102] Step S1: The first catalyst C is filled into an isomerization reactor (fixed-bed reactor) equipped with a heating and insulation device. The reactor tube diameter is 20 mm, the tube length is 2000 mm, and the catalyst filling height is 200 mm. Before the reaction, the reactor is purged three times with nitrogen. After the reaction starts, hydrogen and nitrogen are introduced from the top of the reactor under the control of gas flow meters. At the same time, the feedstock 2,7-octadien-1-ol is pumped into the preheater via a plunger pump and a pipeline with heating, and the preheating temperature is 50°C. Then, the feedstock is mixed with the nitrogen-hydrogen mixture and introduced into the fixed-bed reactor in a co-current flow from the top of the reactor. The hydrogen flow rate is controlled so that the molar ratio of feedstock 2,7-octadien-1-ol to hydrogen is 1:1.8, and the volumetric flow rate ratio of hydrogen to nitrogen is 40:60. The reaction bed temperature is controlled at 75°C, the system pressure is controlled at 0.2 MPa, and the residence time is controlled by the mass hourly space velocity, i.e., controlled at 1.0 g feedstock / g catalytic active metal / hour. The equipment runs continuously for 1000 hours, and the reaction liquid is collected from the bottom of the reactor. After multi-stage cooling, the first mixture is obtained.

[0103] Step S2: The second catalyst, 0.8% Rh / SiO2, is filled into a hydrogenation reactor (fixed-bed reactor) equipped with a heating and insulation device. The reactor tube diameter is 20 mm, the tube length is 2000 mm, and the catalyst filling height is 200 mm. Before the reaction, the reactor is purged three times with nitrogen. After the reaction starts, hydrogen is introduced from the top of the reactor under the control of a gas flow meter. Simultaneously, the first mixture obtained in Step S1 is directly pumped from the condenser of the isomerization reaction device in Step S1 into the preheater via a plunger pump and pipeline heating. The preheating temperature is 80°C. Then, the material is mixed with hydrogen and introduced into the fixed-bed hydrogenation reactor in a co-current flow from the top of the reactor. The hydrogen flow rate is controlled so that the molar ratio of the first mixture obtained in Step S1 to hydrogen is 1:1.2. The reaction bed temperature is controlled at 85°C, the system pressure is controlled at 0.5 MPa, and the residence time is controlled by the mass hourly space velocity (MSV), i.e., controlled at 1.0 g feed / g catalytic active metal / hour. The equipment operated continuously for 1000 hours. The reaction liquid was collected from the bottom of the reactor and cooled in multiple stages to obtain a second mixture. After gas chromatography detection and quantification using the correction and normalization method, the conversion rate of the raw material 2,7-octadien-1-ol was stable at 96.6%–99.2%, the selectivity of the product n-octanal was stable at 95.8%–97.5%, the selectivity of n-octanol was stable at 1.1%–3.2%, the ratio of n-octanal to n-octanol was stable at 30–88:1, and the selectivity of other components and high-boiling products was less than 1%.

[0104] Step S3: Take 500g of the second mixture obtained in Step S2 and place it in the reboiler of a distillation column for distillation purification (the distillation column is 1.5m high, 30cm inner diameter, and filled with 1.2m of Westerley ring packing). Control the vacuum degree of the distillation column at 0.5kPaA, the reboiler temperature at 65-90℃, and the top temperature at 25-45℃. Within this top temperature range, n-octanal purity of over 99% can be obtained. Continue the distillation operation, with the reboiler temperature at 90-105℃ and the top temperature at 48-55℃. Within this top temperature range, n-octanol purity of over 99% can be obtained. 4.3g of high-boiling-point heavy components remain in the reboiler, and 4.5g of light components are lost. The total distillation yield of n-octanal and n-octanol is 98.97%.

[0105] Industrial availability

[0106] According to the method of the present invention, n-aldehydes can be advantageously produced industrially. For example, high-purity n-octanal can be efficiently prepared from 2,7-octadien-1-ol via an isomerization-hydrogenation reaction. This n-octanal can be further oxidized to n-octanoic acid, which can be used commercially as a starting material for the production of lubricants, drying agents, etc.; it can also be reacted with ammonia and hydrogen to be converted to n-octylamine, which can be used to produce precious metal extractants, surfactants, etc.; or it can be reacted with benzaldehyde to produce fragrances such as hexylcinnamaldehyde. The continuous reaction method for preparing n-aldehydes of the present invention has significant industrial application value.

[0107] It should be noted that the above description is a further detailed explanation of the present invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the present invention to these descriptions; the dimensional data in this embodiment do not necessarily limit the technical solution, but merely illustrate one specific working condition. For those skilled in the art, various simple improvements and modifications can be made without departing from the concept of the present invention, and all such improvements and modifications should be considered to fall within the scope of protection of the present invention.

Claims

1. A process for the continuous reaction production of normal aldehydes, characterized in that, The method comprises the following steps: S1, isomerization of a non-conjugated allyl alcohol under a hydrogen-containing atmosphere in the presence of a first catalyst to obtain a first mixture; the non-conjugated allyl alcohol is an allyl alcohol compound having a carbon-carbon double bond alkenyl group at the other end of the molecule; the isomerization temperature is 50-120°C; S2, hydrogenation of the first mixture in the presence of a second catalyst to obtain a second mixture; S3, purification of the second mixture by rectification to obtain the normal aldehyde; The first catalyst is a supported catalyst comprising a main metal as an active component and an auxiliary metal as an active auxiliary agent; the main metal is selected from at least one of rhodium, ruthenium, palladium, platinum and iridium; the auxiliary metal is selected from at least one of cerium, lanthanum, praseodymium, zinc, manganese, cobalt and nickel; the second catalyst is a supported catalyst with an active component selected from at least one of rhodium, ruthenium, palladium, platinum, nickel and cobalt, or at least one of Raney nickel and Raney cobalt; The carrier of the first catalyst is selected from at least one of alumina, activated carbon, silicon oxide, titanium oxide, zirconium oxide, molecular sieve and hydrotalcite; The hydrogen-containing atmosphere in step (1) is pure hydrogen atmosphere or hydrogen atmosphere containing inert gas; when the hydrogen-containing atmosphere is hydrogen atmosphere containing inert gas, the volume ratio of hydrogen to inert gas is 99:1-1:99; The mass ratio of the active component to the carrier in the first catalyst is (0.001-0.05):1; The mass ratio of the active auxiliary agent to the active component is (0.001-1):

1.

2. The method of claim 1, wherein the reaction is carried out continuously. The mass ratio of the active component to the carrier in the first catalyst is (0.003-0.03):

1.

3. The method of claim 1, wherein the reaction is continuous. 3 The mass ratio of the active auxiliary agent to the active component is (0.05-0.5):

1.

4. The method of claim 1, wherein the reaction is continuous. The mass space velocity of the raw material in step (1) is 0.1-20 g / g / h.

5. The method of claim 4, wherein the reaction is carried out continuously. The mass space velocity of the raw material in step (1) is 0.5-10 g / g / h.

6. The method of claim 5, wherein the reaction is carried out continuously. The mass space velocity of the raw material in step (1) is 0.6-5 g / g / h.

7. The method of claim 1, wherein the reaction is continuous. The isomerization temperature is 60-100°C.

8. The method for preparing n-aldehydes by continuous reaction according to claim 1, characterized in that, The reaction pressure of the isomerization is 0.1-1 MPa.

9. The method for preparing n-aldehydes by continuous reaction according to claim 8, characterized in that, The reaction pressure of the isomerization is 0.1-0.5 MPa.

10. The method of claim 1, wherein the method is continuous. 10 The hydrogenation temperature is 50-120°C; the reaction pressure is 0.1-1 MPa.

11. The method of claim 10, wherein the reaction is carried out continuously. The hydrogenation temperature is 60-100°C.

12. The method for preparing n-aldehydes by continuous reaction according to claim 10, characterized in that, The reaction pressure of the hydrogenation is 0.1-0.5 MPa.

13. The method of claim 1, wherein the reaction is continuous. The molar ratio of hydrogen to raw material in the hydrogen-containing atmosphere is 1.5:1-10:

1.

14. The method of claim 13, wherein the reaction is carried out continuously. The molar ratio of hydrogen to raw material in the hydrogen-containing atmosphere is 2:1-6:

1.

15. The method for preparing n-aldehydes by continuous reaction according to claim 1, characterized in that, When the hydrogen-containing atmosphere is hydrogen atmosphere containing inert gas, the volume ratio of hydrogen to inert gas is 95:5-50:

50.

16. The method of claim 1, wherein the reaction is continuous. The number of carbon atoms of the non-conjugated allyl alcohol is 6-12.

17. The method for preparing n-aldehydes by continuous reaction according to claim 16, characterized in that, The non-conjugated allyl alcohol is selected from at least one of 2,5-hexadien-1-ol, 2,6-heptadien-1-ol, 2,7-octadien-1-ol, 2,8-nonadien-1-ol, 2,9-decadien-1-ol, 2,10-undecadien-1-ol, 2,11-dodecadien-1-ol. The non-conjugated allyl alcohol is selected from at least one of 2,5-hexadien-1-ol, 2,6-heptadien-1-ol, 2,7-octadien-1-ol, 2,8-nonadien-1-ol, 2,9-decadien-1-ol, 2,10-undecadien-1-ol, 2,11-dodecadien-1-ol.

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