Process for the continuous dehydrogenation of primary aliphatic alcohols to aldehydes

Abstract

The application discloses a catalyst for preparing aldehyde by dehydrogenation of primary aliphatic alcohol, which is a three-dimensional network structure ruthenium-copper catalyst and comprises 0.1-10% of ruthenium element, 0.01-5.0% of copper element and the rest of carriers in percentage by weight. The catalyst can efficiently catalyze the gas-phase dehydrogenation of primary aliphatic alcohol, and continuously catalyze the dehydrogenation of primary aliphatic alcohol to prepare aldehyde in a fixed bed. The catalyst overcomes the defects of complex operation and poor selectivity of traditional tank type process, has excellent alcohol conversion rate, aldehyde selectivity and repeated use stability, and has wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical engineering and catalysis, and relates to a catalyst for dehydrogenation of primary aliphatic alcohols to aldehydes and a method for continuous dehydrogenation of primary aliphatic alcohols to aldehydes. BACKGROUND

[0002] Carbonyl compounds such as propionaldehyde, n-butyraldehyde, isoamyl aldehyde, n-octyl aldehyde, etc. are important bulk chemicals, often used as intermediates in organic synthesis for the synthesis of products such as resins, flavors, food additives, pesticides, etc. At present, there is a large demand for aliphatic aldehydes worldwide, at least 10 million tons per year, which are generally prepared by catalytic conversion of primary aliphatic alcohols. Depending on the catalyst and reaction conditions, the conversion of primary aliphatic alcohols to aliphatic aldehydes can be divided into two categories: catalytic oxidation of primary aliphatic alcohols to aldehydes and catalytic dehydrogenation of primary aliphatic alcohols to aldehydes; depending on the reaction mode, the process can be divided into batch and continuous processes.

[0003] Catalytic oxidation of primary aliphatic alcohols is generally carried out by using molecular oxygen as the oxidant for the oxidation of aliphatic alcohols. Due to the difficulty in fine control of this process, it often leads to over-oxidation to form carboxylic acids, and such oxidation reactions require high temperature and high pressure. Under high temperature conditions, organic alcohol compounds are easy to explode when in contact with oxygen. In contrast, catalytic dehydrogenation of primary aliphatic alcohols is relatively mild, can avoid further conversion of aldehydes to carboxylic acids, and achieve high selectivity for the preparation of aldehydes. Patent document CN1238320C discloses a catalyst using copper oxide, which catalyzes the dehydrogenation of primary aliphatic alcohols to prepare the corresponding aldehyde under gas phase conditions. This method requires high temperature (300°C), which can easily produce carboxylic acids, resulting in a decrease in the selectivity of aldehydes. Patent document CN104707612A discloses a catalyst that can be used for the dehydrogenation of primary aliphatic alcohols to prepare aldehydes, which is prepared by using active alumina, porous silica or active carbon as the carrier, and copper as the main active component, and cobalt, nickel, manganese, iron, etc. as the auxiliary agent. It can achieve high selectivity for the dehydrogenation of primary aliphatic alcohols to prepare the corresponding aldehyde. However, this method uses a kettle operation, and a complex post-treatment process is required after the reaction, and the activity of the catalyst gradually decreases with the increase of the number of times of use, which requires an additional regeneration process. Literature (Angew. Chem. Int. Ed. 2008, 47, 138-141) reports a catalyst using hydrotalcite supported silver nanoparticles to catalyze the dehydrogenation of aromatic alcohols to prepare the corresponding aldehyde under mild conditions, with a conversion rate and selectivity of more than 90%. However, the activity of this catalyst for the dehydrogenation of primary aliphatic alcohols is low. SUMMARY

[0004] In order to overcome the above-mentioned shortcomings of the above-mentioned method for preparing aliphatic aldehydes by kettle reaction, the inventors have improved the fixed bed reaction process, and provided a catalyst system and mild continuous catalytic process specially adapted for the continuous dehydrogenation reaction of primary aliphatic alcohols in a fixed bed. Specifically, the present application comprises the following technical solutions.

[0005] A catalyst for dehydrogenation of a primary aliphatic alcohol to aldehyde, characterized in that it is a three-dimensional network structure ruthenium-copper catalyst, which takes the ruthenium atom or atom cluster as the active center and the copper atom as the cocatalyst, is attached to the carrier and has a three-dimensional network structure, and contains 0.1-10% of ruthenium element, 0.01-5.0% of copper element and the balance of the carrier by weight percentage.

[0006] Preferably, the above carrier is silicon oxide. When the carrier is silicon oxide, the catalyst for dehydrogenation of a primary aliphatic alcohol to aldehyde can be expressed as x%Ru-y%Cu-SiO2 (or expressed as x%Ru-y%Cu / SiO2), wherein x is 0.1-10, preferably 0.5-8, more preferably 0.8-7, more preferably 1-5, and y is 0.01-5.0, preferably 0.05-4.0, more preferably 0.08-3.0, more preferably 0.1-2.0.

[0007] The above primary aliphatic alcohol preferably refers to a normal or isomeric alcohol of C3-C10, such as isoamyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol and the like.

[0008] In one embodiment, the catalyst for dehydrogenation of a primary aliphatic alcohol to aldehyde can be prepared by the following method: dissolving a ruthenium salt and a silicate in an alcohol to form a transparent sol, pouring the upper clear night after aging overnight, and converting the solid into a gel by heating and drying, and then calcining to obtain a x%Ru-SiO2 (or expressed as x%Ru / SiO2) three-dimensional network structure of the main catalyst solid; preparing an aqueous copper salt solution, immersing the x%Ru / SiO2 solid in the aqueous copper salt solution, and ultrasonic treatment to promote adsorption, and then filtering, heating, drying and calcining to obtain the x%Ru-y%Cu-SiO2 catalyst.

[0009] The above ruthenium salt can be selected from ruthenium nitrate, ruthenium chloride, ruthenium acetate and ruthenium sulfate, but is not limited thereto; the silicate refers to orthosilicate, which can be selected from methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate, but is not limited thereto; the alcohol can be selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, 3-pentanol, 2-pentanol and tert-amyl alcohol, but is not limited thereto; and the copper salt can be selected from copper nitrate, copper chloride, cuprous chloride, copper acetate and copper sulfate, but is not limited thereto.

[0010] Preferably, the ruthenium salt is acetate, the silicate is butyl orthosilicate, the alcohol is ethanol, and the copper salt is copper acetate.

[0011] In one specific embodiment, the aldehyde catalyst for the dehydrogenation of primary aliphatic alcohols can be prepared by the following method: dissolve ruthenium acetate and n-butyl orthosilicate in ethanol to form a transparent sol, pour the supernatant clear night after aging overnight, and the solid is dried at about 100°C to convert into a gel, and the x% Ru / SiO2 three-dimensional network structure main catalyst is obtained by calcination at about 550°C; dissolve copper acetate in purified water, and immerse the x% Ru / SiO2 solid in the above solution, and promote adsorption by ultrasonic treatment at about 60°C for 5h, and then filter, dry at about 120°C, and calcine at about 500°C to obtain the x% Ru-y% Cu-SiO2 catalyst.

[0012] The formation of the transparent sol, aging (or aging, curing), and solidification into a gel process makes the ruthenium element uniformly distributed in the silicic acid environment, and after high-temperature calcination, the ruthenium element is fixed and distributed in situ in the three-dimensional network of silicon oxide, and the ruthenium atoms or atomic clusters as the active centers of the catalyst exhibit maximum specific surface area exposure. The three-dimensional network structure main catalyst Ru / SiO2 is immersed in a copper acetate aqueous solution, and ultrasonic treatment further promotes the uniform distribution and sufficient adsorption of copper elements in the three-dimensional network structure, and high-temperature calcination makes the copper atoms also uniformly distributed in situ around the ruthenium atoms or atomic clusters in the three-dimensional network structure, so that there are cooperations between copper atoms and ruthenium atoms in any Ru-Cu / SiO2 microenvironment / lattice of the catalyst, and the two fully play a synergistic role in the catalytic reaction.

[0013] It should be understood that the terms "about", "approximately" or "around" in the expression of numerical characteristics herein refer to the indicated number can have a ±10%, ±9%, ±8%, ±7%, ±6% or ±5% error range or floating range.

[0014] Another aspect of the present application is to provide a method for the continuous dehydrogenation of primary aliphatic alcohols to prepare aldehydes, which uses a fixed bed reactor, and under the action of the aldehyde catalyst for the dehydrogenation of primary aliphatic alcohols described above, the raw material primary aliphatic alcohol undergoes a gas phase dehydrogenation reaction to prepare the corresponding primary aliphatic aldehyde.

[0015] Preferably, the fixed bed reactor is a fixed bed of tubes, and the inner diameter of the tube is preferably 15-25mm.

[0016] In one specific embodiment, referring to Figure 1, the fixed bed reactor comprises: raw material (fatty primary alcohol) gasifier, reactor, cooler, gas-liquid separation tank, tail gas tank, product tank. The gasifier is provided with a liquid raw material inlet end and a gaseous raw material outlet end, the outlet end is connected with the inlet end of the reactor through a pipeline, the outlet end of the reactor is connected with the gas-liquid separation tank through a pipeline, and a cooler is arranged on the pipeline between the reactor and the gas-liquid separation tank, the gas phase outlet of the gas-liquid separation tank is connected with the tail gas tank and then connected to a tail gas treatment device, and the liquid phase outlet of the gas-liquid separation tank is connected with the product tank, and the product mixture enters a subsequent separation and rectification stage.

[0017] In the above method, in addition to the catalyst, an appropriate amount of inert carrier such as quartz sand, inert alumina ball, etc. is filled in the fixed bed, and the filling amount of the inert carrier is 10-150 wt% of the filling amount of the catalyst.

[0018] In a preferred embodiment, the temperature of the fixed bed gasifier is set to 200-400 DEG C, the temperature of the reactor is set to 200-400 DEG C, and the specific temperature is selected according to the different fatty primary alcohols; the volume space velocity of the fatty primary alcohol in the fixed bed reactor is 0.2-5.0 h -1 .

[0019] The fatty primary alcohol dehydrogenation catalyst developed by the application has strong stability, high conversion rate of fatty primary alcohol and good selectivity of fatty primary aldehyde, and can be applied to a fixed bed reaction device to realize continuous dehydrogenation of fatty primary aldehyde, the reaction conditions are mild, the disadvantages of complex operation and poor selectivity of traditional tank type process are overcome, and the application prospect is wide. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a process flow chart for continuous dehydrogenation of fatty primary alcohol using a fixed bed reactor to prepare aldehyde. In the figure, 1 is a raw material tank, 3 is a gasifier, 5 is a fixed bed reactor, 6 is a cooler, 7 is a gas-liquid separation tank, 10 is a tail gas tank, 11 is a product tank, 2, 4, 8 and 9 are valves.

[0021] Figure 2 is the HRMS spectrum of isopentanal prepared by the application.

[0022] Figure 3 is the HRMS spectrum of n-heptanal prepared by the application.

[0023] Figure 4 is the HRMS spectrum of n-hexanal prepared by the application.

[0024] Figure 5 is the HRMS spectrum of n-octanal prepared by the application. DETAILED DESCRIPTION

[0025] It is the goal of the art to improve the conversion of primary aliphatic alcohols, the selectivity of the product primary aliphatic aldehydes, the stability of the catalysts upon repeated use, and to enable continuous dehydrogenation. To this end, the inventors have first improved the structure of the ruthenium-based catalysts, and have experimented with inert supports, including molecular sieves, diatomaceous earth, alumina (including calcined alpha-alumina, high purity alumina, activated alumina, etc.), silica, titania, zirconia, activated carbon, hydrotalcite, kaolin, etc., to immobilize the ruthenium atoms or clusters of atoms, which are the catalytically active centers, on the supports and form a three-dimensional network structure, which increases the specific surface area while improving the mechanical strength of the catalysts. After repeated comparisons, the inventors have found that silica is a relatively ideal support, and the x%Ru / SiO2 (wherein x is preferably 1-8) catalysts formed therefrom are relatively outstanding in terms of the three indicators of raw material conversion, product selectivity, and stability upon repeated use.

[0026] In the reaction of dehydrogenation of primary aliphatic alcohols to primary aliphatic aldehydes catalyzed by x%Ru / SiO2, there is always the production of by-products, alkenes. To reduce the occurrence of side reactions, the inventors have tried two improvement schemes: one is to add a ligand compound to the catalyst as a ligand of the ruthenium element, and the other is to use ruthenium as the main catalyst and add other metal elements (such as iron, cerium, copper, tungsten, magnesium, calcium, rhodium, palladium, platinum, iridium, osmium, rhenium, praseodymium, zinc, manganese, cobalt, nickel, etc.) as a co-catalyst (auxiliary agent). After a large number of experiments and comparisons, the inventors have found that the use of a small amount of copper as a co-catalyst unexpectedly achieves ideal results, not only significantly reducing the generation of by-products, alkenes, but also further improving the conversion of the raw material primary aliphatic alcohols and the selectivity of the product primary aliphatic aldehydes. On the basis of the x%Ru / SiO2 (wherein x is preferably 1-8) catalyst, the addition of copper elements forms a three-dimensional network structure of Ru-Cu-SiO2 (or represented as Ru-Cu / SiO2) catalyst, i.e., a ruthenium-copper-based catalyst.

[0027] For the sake of convenience of description, the "aliphatic alcohol dehydrogenation catalyst" of the present application is sometimes referred to herein as "aliphatic alcohol dehydrogenation catalyst", "ruthenium-copper-based catalyst", or "ruthenium-copper catalyst". Correspondingly, the Ru / SiO2 catalyst can be referred to as "main catalyst" or "ruthenium catalyst".

[0028] It is readily understood that the term "primary aliphatic aldehyde" refers to "aliphatic aldehyde" having a molecular structure corresponding to the precursor "primary aliphatic alcohol".

[0029] In the x%Ru-y%Cu-SiO2catalyst, x can range from 0.1 to 10. When the content of ruthenium is lower than 0.1%, the catalytic activity of the catalyst is significantly reduced, and it is difficult to quickly and effectively catalyze the dehydrogenation reaction of the primary aliphatic alcohol. When the content is higher than 10%, the balance effect of significantly improving the catalytic activity cannot be achieved, and the production cost of the catalyst is increased, resulting in a decrease in economic efficiency. Preferably, x ranges from 0.5 to 8, more preferably from 0.8 to 6, and more preferably from 1 to 5.

[0030] In the x%Ru-y%Cu-SiO2catalyst, y can range from 0.01 to 5.0. When the content of copper is lower than 0.1%, the yield of the byproduct olefin cannot be reduced, and / or the catalytic efficiency of the main catalyst x%Ru / SiO2cannot be improved. When the content is higher than 5%, the catalytic efficiency of the main catalyst Ru / SiO2cannot be further improved, and the selectivity of the primary aliphatic aldehyde is reduced, and even the yield of the byproduct olefin is increased. Preferably, y is 0.05 to 4.0, more preferably 0.08 to 3.0, and more preferably 0.1 to 2.0.

[0031] To form a three-dimensional network structure of the Ru-Cu-SiO2catalyst, a suitable catalyst preparation process needs to be used. It is found that the performance of the catalyst prepared by adding ruthenium and copper in sequence, especially the conversion rate of the primary aliphatic alcohol, is superior to that of the catalyst prepared by simultaneously adding a ruthenium and copper mixture. That is, it is preferred to first form a gel of a ruthenium salt and a silicate ester, and then to obtain a three-dimensional network structure of the Ru / SiO2main catalyst by calcination, so that ruthenium atoms or atomic clusters are fully dispersed in the network structure to form catalytically active centers. Then, the promoter copper atoms are dispersedly loaded in the network structure, and finally a three-dimensional network structure of the Ru-Cu-SiO2catalyst is obtained. In this way, the comprehensive performance of the raw material primary aliphatic alcohol conversion rate, the product primary aliphatic aldehyde selectivity, and the reuse stability can be improved.

[0032] The three-dimensional network structure enables the catalyst to have a certain mechanical strength, and endows it with reuse stability, so that it is suitable for use in a continuous reaction fixed bed reactor. In an embodiment, the fixed bed reactor is a fixed bed of tubes, and the tube body inner diameter can be, for example, 15-25 mm. In addition to the Ru-Cu-SiO2catalyst, an appropriate amount of inert carrier such as quartz sand, inert alumina balls, etc. can be filled in the fixed bed, and the filling amount of the inert carrier can be 10-150 wt% of the filling amount of the catalyst.

[0033] After filling the inert carrier in the fixed bed, the travel path of the raw material primary aliphatic alcohol in the tube can be extended, the residence time of the raw material primary aliphatic alcohol in the reactor can be extended, and the reaction raw material and the catalyst can be fully contacted, so that the raw material is fully reacted and the conversion rate is improved.

[0034] The production device used in the production method of the present application comprises necessary auxiliary devices and post-processing devices in addition to the fixed bed reactor, such as a raw material gasifier, a reactor, a cooler, a gas-liquid separation tank, a tail gas tank, a product tank, etc. See Figure 1 For example, the production device used comprises a raw material tank 1, a raw material gasifier 3, a fixed bed reactor 5, a cooler 6, a gas-liquid separation tank 7, a tail gas tank 10, a product tank 11, and valves 2, 4, 8, 9.

[0035] The raw material gasifier 3 is used for gasification of the raw material primary aliphatic alcohol, and the primary aliphatic alcohol is heated to a high-temperature gasification state and then input into the fixed bed reactor 5.

[0036] The fixed bed reactor 5 is filled with a Ru-SiO2 or Ru-Cu-SiO2 dehydrogenation catalyst, and the gaseous raw material undergoes a dehydrogenation reaction on the surface and inside the pores of the catalyst to generate aldehyde and hydrogen. However, side reactions such as dehydration to produce olefins can also occur during the reaction.

[0037] The cooler 6 is used to cool the gaseous product output from the reactor 5, so that the primary aliphatic aldehyde is liquefied, in order to separate the gas from the liquid product through the subsequent gas-liquid separation tank.

[0038] The gas-liquid separation tank 7 is used for separation of gaseous and liquid substances, and the gas is output from the gas phase outlet at the top into the tail gas tank 10 and then into the waste gas treatment system, and the liquid is output from the liquid phase outlet at the bottom into the product tank 11.

[0039] Continuous reaction operation process: after the reaction system is replaced by nitrogen, the raw material primary aliphatic alcohol is metered and then input into the gasifier 3 for gasification, the valve 2 is opened to allow the gas to enter the fixed bed reactor 5 filled with catalyst and inert carrier, and the reaction liquid after the dehydrogenation reaction is cooled by the cooler 6 and then input into the gas-liquid separation tank 7. After gas-liquid separation, the gas is output from the gas phase outlet at the top of the gas-liquid separation tank into the tail gas tank 10. The liquid is output from the liquid phase outlet at the bottom of the gas-liquid separation tank into the product tank 11, and the entire production process can be controlled by adjusting the temperature of the gasifier and the fixed bed reactor to control the temperature of the dehydrogenation reaction.

[0040] During continuous reaction, the temperature of the gasifier can be set to 200-400°C, and the temperature of the fixed bed reactor can be set to 200-400°C. The appropriate temperature can be selected according to the different primary aliphatic alcohols, and the skilled person can determine it through limited simple experiments. Since the reaction temperature is much lower than that of the batch kettle reaction, the occurrence of side reactions can be reduced. At the same time, continuous reaction is easier to achieve automatic control, and reduces the defects of unstable product quality caused by batch reaction, thus being beneficial to quality control.

[0041] Compared with the prior art, the dehydrogenation catalyst active component used in the method has uniform dispersion, larger specific surface area, more sufficient contact with reaction gas, and higher stability, and can be used stably for thousands of hours; the fixed bed is used as the reactor, the structure is simple, the equipment cost can be significantly reduced, the production process is simplified, the energy consumption is reduced, and the production efficiency is improved.

[0042] In order to make the present application more apparent and easy to understand, the preferred embodiments are described in detail as follows. Those skilled in the art should understand that the following embodiments are only used to illustrate the present application, and are not intended to limit the present application.

[0043] Embodiments

[0044] In the embodiments, the addition amount, content and concentration of various substances are involved, wherein the "parts" refer to "weight parts" unless otherwise specified; the percentage content refers to weight percentage content unless otherwise specified.

[0045] In the embodiments, if no specific description is made for the temperature of experimental operation, the temperature generally refers to room temperature (10-30℃).

[0046] Product analysis method:

[0047] High resolution mass spectrometer (HRMS): Agilent 7890B-5977A, auxiliary heating temperature: 280℃; ion source temperature: 230℃; quadrupole temperature: 150℃; acquisition mode: scan, 0min start, low mass: 29, high mass: 300. Chromatographic column: HP-5MS chromatographic column, 30m*0.25mm, 0.25 microns; column oven: 50℃, hold for 5min, increase to 250℃ at 20℃ / min, 10min; injection port temperature: 250℃, split ratio: 100:1; injection amount: 0.1ul.

[0048] Gas chromatograph: Agilent 7820A, HP-5 chromatographic column, injection port temperature: 150℃; split ratio: 50:1; carrier gas flow rate: 2ml / min; temperature rising program: 50℃ for 5min, increase to 90℃ at 10℃ / min, hold for 5min; increase to 160℃ at 10℃ / min, hold for 5min; finally increase to 280℃ at 30℃ / min, hold for 6min. Detector temperature: 280℃.

[0049] Example 1: Preparation of isovaleraldehyde by catalyzing dehydrogenation of isopentyl alcohol with a ruthenium catalyst

[0050] 1.1 Catalyst preparation

[0051] Ruthenium catalyst x%Ru-SiO2:

[0052] A certain amount of ruthenium acetate and tetraethyl orthosilicate were dissolved in ethanol to form a transparent sol. After aging overnight, the upper clear solution was decanted and the solid was dried at 100 °C to convert into a gel, which was calcined at 550 °C to obtain the x%Ru / SiO2 catalyst.

[0053] Ruthenium-copper catalyst x%Ru-y%Cu-SiO2:

[0054] A certain amount of copper acetate was dissolved in purified water. The x%Ru / SiO2 catalyst was immersed in the copper acetate solution and heated at 60 °C for 5 h with ultrasonic to promote adsorption. After filtration, drying at 120 °C and calcination at 500 °C, the x%Ru-y%Cu-SiO2 catalyst was obtained.

[0055] 1.2 Fixed-bed continuous reaction

[0056] The loading of metallic ruthenium was adjusted to obtain the 1%Ru / SiO2 catalyst with x = 1. After crushing and tabletting, the catalyst was obtained in the form of particles with a diameter of 6 mm. 20 g of the shaped catalyst and 10 g of quartz sand were loaded into a fixed-bed reactor. After replacement with nitrogen, the gasifier and the reactor were heated to 250 °C. The volume space velocity of isopentyl alcohol was 3.6 h-1. Sampling was started after one hour of reaction. The product composition was analyzed by gas chromatography. The results are as follows: the conversion of isopentyl alcohol was 90.7%, the selectivity of isopentyl aldehyde was 95.9%, and the main by-product was isopentene, about 3.0%. Product characterization: HRMS m / z: [M+H] -1 Calcd for C5H + O, Found 86. 10 Figure 2 .

[0057] Example 2: Ruthenium-copper catalyst for catalyzing the dehydrogenation of isopentyl alcohol to prepare isopentyl aldehyde

[0058] 2.1 According to the method of Example 1.1, the loading of metallic ruthenium and copper was adjusted to obtain the ruthenium-copper catalyst 3%Ru-0.4%Cu / SiO2 with x = 3 and y = 0.4, which was applied to catalyze the dehydrogenation of isopentyl alcohol to prepare isopentyl aldehyde. The catalyst was tabletted to obtain catalyst particles with a diameter of 6 mm. 20 g of the shaped catalyst and 20 g of inert alumina balls were loaded into a fixed-bed reactor. After replacement with nitrogen, the gasifier and the reactor were heated to 300 °C. The volume space velocity of isopentyl alcohol was maintained at 3.6 h-1. Sampling was started after one hour of reaction. The product composition was analyzed by gas chromatography. The conversion of isopentyl alcohol was 95.6%, the selectivity of isopentyl aldehyde was 98.5%, and the main by-product was isopentene, about 0.9%. Product characterization: HRMS m / z: [M+H] -1 Calcd for C5H + O, Found 86. 10

[0059] ​​2.2 Adjusting the loading of metal ruthenium and copper, different x and y of ruthenium-copper catalysts were prepared, and according to the same method as in Example 2.1, catalyzing the dehydrogenation of isoamyl alcohol to prepare isoamyl aldehyde, the results are shown in Table 1.

[0060] Table 1, x%Ru-y%Cu-SiO2 catalyst catalyzing the dehydrogenation of isoamyl alcohol to prepare isoamyl aldehyde

[0061] Serial number x y Temperature °C Conversion % Selectivity % Isoamylene 1 1 0.5 250 94.0 96.4 0.8 2 2 1.0 250 95.9 98.0 0.3 3 3 0.2 250 96.1 97.8 0.4 4 4 1.5 300 97.1 96.9 0.1 5 4 2.0 300 96.4 98.3 0.2 6 5 0.3 300 96.1 97.6 0.2

[0062] As can be seen from Table 1, compared with the ruthenium catalyst Ru-SiO2, after adding the cocatalyst copper, the ruthenium-copper catalyst Ru-Cu-SiO2 with x = 1-5, y = 0.2-2.0 has a certain degree of improvement in raw material conversion rate and product selectivity in the dehydrogenation of isoamyl alcohol to prepare isoamyl aldehyde, and the byproduct yield is significantly reduced.

[0063] Example 3: Ruthenium catalyst catalyzing the dehydrogenation of n-heptyl alcohol to prepare n-heptyl aldehyde

[0064] According to the method of Example 1.1, adjusting the loading of metal ruthenium, 3%Ru / SiO2 catalyst with x = 3 was prepared and applied to catalyze the dehydrogenation of n-heptyl alcohol to prepare n-heptyl aldehyde. The catalyst was crushed and tableted to obtain particles with a diameter of 6 mm. 40 g of the formed catalyst and 40 g of inert alumina balls were loaded into a fixed bed reactor, and after nitrogen replacement, the gasifier and the reactor were both heated to 280°C, and the n-heptyl alcohol volume space velocity was 3.1 h -1 . After one hour of reaction, sampling was started, and the product composition was analyzed by gas chromatography. The results are as follows: the conversion rate of n-heptyl alcohol is 92.6%, the selectivity of n-heptyl aldehyde is 93.9%, and the main byproduct is olefin produced by dehydration, about 1.2%. Product characterization: HRMS m / z: [M+H] + Calcd for C7H 14 O, Found 114 ( Figure 3 ).

[0065] Example 4: Ruthenium-copper catalyst catalyzing the dehydrogenation of n-heptyl alcohol to prepare n-heptyl aldehyde

[0066] According to the method of Example 1.1, adjusting the loading of metal ruthenium and copper, a ruthenium-copper catalyst 3%Ru-1.0%Cu / SiO2 with x = 3, y = 1.0 was prepared and applied to catalyze the dehydrogenation of n-heptyl alcohol. The prepared catalyst was crushed and tableted to obtain catalyst particles with a diameter of 6 mm. 50 g of the above formed catalyst and 20 g of quartz sand were loaded into a fixed bed reactor, and after nitrogen replacement, the gasifier and the reactor were both heated to 280°C, and the n-heptyl alcohol volume space velocity was maintained at 3.1 h -1The reaction was sampled after one hour and the product composition was analyzed by gas chromatography. The conversion of n-hexanol was 96.0% and the selectivity of n-hexanal was 97.8% with about 0.2% of by-product olefin. Product characterization: HRMS m / z: [M+H] + Calcd for C7H 14 O, Found 114.

[0067] Example 5: Dehydrogenation of n-hexanol to n-hexanal catalyzed by ruthenium catalyst

[0068] A 5% Ru / Si02 catalyst with x = 5 was prepared according to the method of Example 1.1 by adjusting the loading of ruthenium metal and was applied to catalyze the dehydrogenation of n-hexanol to n-hexanal. The prepared catalyst was crushed and tabletted to obtain catalyst particles with a diameter of 6 mm. 30 g of the above formed catalyst and 10 g of quartz sand were loaded into a fixed bed reactor, which was heated to 300°C after nitrogen replacement. The volume space velocity of n-hexanol was maintained at 3.0 h -1 The reaction was sampled after one hour and the product composition was analyzed by gas chromatography. The conversion of n-hexanol was 85.2% and the selectivity of aldehyde was 95.8% with about 1.1% of by-product olefin. Product characterization: HRMS m / z: [M+H] + Calcd for C6H 12 O, Found 100. Figure 4

[0069] Example 6: Dehydrogenation of n-hexanol to n-hexanal catalyzed by ruthenium-copper catalyst

[0070] A 5% Ru-1% Cu / Si02 catalyst with x = 5, y = 1 was prepared according to the method of Example 1.1 by adjusting the loading of ruthenium and copper metals and was applied to catalyze the dehydrogenation of n-hexanol. The prepared catalyst was crushed and tabletted to obtain catalyst particles with a diameter of 6 mm. 50 g of the above formed catalyst and 20 g of quartz sand were loaded into a fixed bed reactor, which was heated to 300°C after nitrogen replacement. The volume space velocity of n-hexanol was maintained at 2.5 h -1 The reaction was sampled after one hour and the product composition was analyzed by gas chromatography. The conversion of n-hexanol was 95.0% and the selectivity of n-hexanal was 97.6% with about 0.2% of by-product olefin. Product characterization: HRMS m / z: [M+H] + Calcd for C6H 12 O, Found 100.

[0071] Example 7: Dehydrogenation of n-octanol to n-octanal catalyzed by ruthenium catalyst

[0072] ​A 3% Ru / SiO2 catalyst with x = 3 was prepared according to the method of Example 1.1 by adjusting the loading of ruthenium metal and was used to catalyze the dehydrogenation of n-octanol to produce n-octanal. The prepared catalyst was crushed and tabletted to obtain catalyst particles with a diameter of 6 mm. 20 g of the above formed catalyst and 30 g of quartz sand were loaded into a fixed bed reactor, the gasifier and the reactor were heated to 280°C after nitrogen replacement, and the volume space velocity of n-octanol was maintained at 3.5 h -1 . Sampling was started after one hour of reaction, and the product composition was analyzed by gas chromatography. The conversion rate of n-octanol was 88.3%, the selectivity of aldehyde was 93.1%, and the main by-product was the olefin produced by dehydration of alcohol, which was about 1.8%. Product characterization: HRMS m / z: [M+H] + Calcd for C8H 16 O, Found 128. Figure 5 .

[0073] Example 8: Ruthenium-copper catalyst catalyzing the dehydrogenation of n-octanol to produce n-octanal

[0074] A 3% Ru-2% Cu / SiO2 catalyst with x = 3, y = 2 was prepared according to the method of Example 1.1 by adjusting the loading of ruthenium and copper metals and was used to catalyze the dehydrogenation of n-octanol. The prepared catalyst was crushed and tabletted to obtain catalyst particles with a diameter of 6 mm. 35 g of the above formed catalyst was loaded into a fixed bed reactor, the gasifier and the reactor were heated to 280°C after nitrogen replacement, and the volume space velocity of n-octanol was maintained at 3.0 h -1 . Sampling was started after one hour of reaction, and the product composition was analyzed by gas chromatography. The conversion rate of n-octanol was 93.1%, the selectivity of n-octanal was 97.6%, and the by-product olefin was about 0.8%. Product characterization: HRMS m / z: [M+H] + Calcd for C8H 16 O, Found 128.

[0075] The above examples show that the catalysts Ru / SiO2 and Ru-Cu / SiO2 with a three-dimensional network structure developed by the present application, especially the catalyst Ru-Cu / SiO2, have strong stability, high raw material conversion rate, and good product selectivity in catalyzing the dehydrogenation of primary aliphatic alcohols. The catalysts can be applied to a fixed bed reaction device to realize the continuous dehydrogenation method for producing aliphatic aldehydes, the reaction conditions are mild, and the method is suitable for large-scale production.

[0076] Although the above only takes isopentyl alcohol, n-hexanol, n-heptanol, n-octanol as an example, the technical solution of the present application is described, but according to the disclosure of the present application, the technical solution of the present application is also applicable to other aldehyde preparation methods of dehydrogenation of fatty primary alcohol, which is obvious to those skilled in the art. Therefore, without departing from the idea of the present application, those skilled in the art can make various modifications or modifications on the basis of the present application, and the equivalent forms of various modifications or modifications made should also belong to the scope of the present application.

Claims

1. A catalyst for the dehydrogenation of aliphatic primary alcohols to aldehydes, characterized in that, The ruthenium-copper catalyst with a three-dimensional network structure comprises, by weight percentage, 0.1-10% ruthenium, 0.01-5.0% copper, and the balance being a support. The catalyst for the dehydrogenation of aliphatic primary alcohols to aldehydes is prepared by the following method: Ruthenium salt and silicate ester were dissolved in alcohol to form a transparent sol. After aging overnight, the supernatant was poured off. The solid was heated and dried to transform into a gel. Calcination yielded the main catalyst solid with an x%Ru / SiO2 three-dimensional network structure. A copper salt aqueous solution was prepared, and x%Ru / SiO2 solid was impregnated in the copper salt aqueous solution. The solid was ultrasonically treated to promote adsorption. The catalyst was then filtered, heated, dried, and calcined to obtain x%Ru-y%Cu-SiO2 catalyst.

2. The catalyst for dehydrogenation of aliphatic primary alcohols to aldehydes as described in claim 1, characterized in that, The support is silicon dioxide, and the catalyst for dehydrogenation of aliphatic primary alcohols to aldehydes is expressed as x%Ru-y%Cu-SiO2, where x is 0.1-10 and y is 0.01-5.

0.

3. The catalyst for dehydrogenation of aliphatic primary alcohols to aldehydes as described in claim 1, characterized in that, The primary aliphatic alcohols refer to C3-C10 normal or isomer alcohols.

4. The catalyst for dehydrogenation of aliphatic primary alcohols to aldehydes as described in claim 1, characterized in that, The ruthenium salt is selected from ruthenium nitrate, ruthenium chloride, ruthenium acetate, and ruthenium sulfate; the silicate ester is an orthosilicate, selected from methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate; the alcohol is selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, 3-pentanol, 2-pentanol, and tert-pentanol; the copper salt is selected from copper nitrate, copper chloride, cuprous chloride, copper acetate, and copper sulfate.

5. The catalyst for the dehydrogenation of aliphatic primary alcohols to aldehydes as described in claim 1, characterized in that, The ruthenium salt is acetate, the silicate ester is butyl orthosilicate, the alcohol is ethanol, and the copper salt is copper acetate.

6. A method for the continuous dehydrogenation of aliphatic primary alcohols to aldehydes, characterized in that, Using a fixed-bed reactor, under the action of the catalyst for dehydrogenation of aliphatic primary alcohols to aldehydes as described in any one of claims 1-5, aliphatic primary alcohols undergo gas-phase dehydrogenation to prepare the corresponding aliphatic primary aldehydes.

7. The method as described in claim 6, characterized in that, The fixed-bed reactor is a tubular fixed-bed reactor with an inner diameter of 15-25 mm.

8. The method as described in claim 6, characterized in that, In addition to the catalyst, the fixed bed also contains an inert support, the amount of which is 10-150 wt% of the catalyst.

9. The method as described in claim 6, characterized in that, The reaction temperature in the fixed-bed reactor is 200-400℃; the volume hourly space velocity (VHSV) of the aliphatic primary alcohols in the fixed-bed reactor is 0.2-5.0 h⁻¹. -1 .

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