CN117983240A

CN117983240A - Method for preparing aldehyde by continuously dehydrogenating aliphatic primary alcohol

Info

Publication number: CN117983240A
Application number: CN202211369479.7A
Authority: CN
Inventors: 史德超; 竺少铭; 陈刚; 卢海湛; 卢琪; 彭后辉; 张雨锋; 王红卫; 孔望欣; 严文斌; 上官光进; 周羽翀
Original assignee: Zhejiang Changbei Biological Co ltd; Zhejiang Fangyuanxin Biopharmaceutical Co ltd; Changhai Biological Branch Of Zhejiang Pharmaceutical Co ltd
Current assignee: Zhejiang Changbei Biological Co ltd; Zhejiang Fangyuanxin Biopharmaceutical Co ltd; Changhai Biological Branch Of Zhejiang Pharmaceutical Co ltd
Priority date: 2022-11-03
Filing date: 2022-11-03
Publication date: 2024-05-07

Abstract

The invention discloses an aldehyde preparation catalyst for dehydrogenation of aliphatic primary 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 balance of carrier according to weight percentage. The catalyst can efficiently catalyze the gas-phase dehydrogenation of the aliphatic primary alcohol, and can catalyze the continuous dehydrogenation of the aliphatic primary alcohol in a fixed bed to prepare the aldehyde, overcomes the defects of complex operation and poor selectivity of the traditional kettle type process, and has excellent alcohol conversion rate, aldehyde selectivity and repeated use stability, and wide industrial application prospect.

Description

Method for preparing aldehyde by continuously dehydrogenating aliphatic primary alcohol

Technical Field

The invention belongs to the field of chemical engineering and catalysis, and relates to a catalyst for preparing aldehyde by dehydrogenating aliphatic primary alcohol and a method for preparing aldehyde by continuously dehydrogenating aliphatic primary alcohol.

Background

Carbonyl compounds such as propionaldehyde, n-butyraldehyde, isovaleraldehyde, n-caprylic aldehyde, etc. are important bulk chemicals and are often used as organic synthesis intermediates in the synthesis of resins, fragrances, food additives, pesticides, etc. Currently, fatty aldehydes are in large scale demand worldwide, at least ten million tons per year, typically produced by catalytic conversion of primary aliphatic alcohols. The conversion of primary aliphatic alcohols to aliphatic aldehydes can be divided into two classes, depending on the catalyst and reaction conditions: catalyzing the oxidation of aliphatic primary alcohol to prepare aldehyde and catalyzing the dehydrogenation of aliphatic primary alcohol to prepare aldehyde; the process is divided into batch type and continuous type according to the different reaction modes.

The oxidation of aliphatic alcohols is catalyzed, and is generally carried out by taking molecular oxygen as an oxidant. Since this process is difficult to control finely, it tends to result in excessive oxidation to produce carboxylic acids, and such oxidation reactions require high temperatures and pressures. Under the high temperature condition, the organic alcohol compound is easy to explode when contacting with oxygen. In contrast, the conditions for catalyzing the dehydrogenation of aliphatic primary alcohols are relatively mild, and the further conversion of aldehydes to carboxylic acids can be avoided, thereby realizing the high-selectivity preparation of aldehydes. Patent document CN1238320C discloses a method for preparing corresponding aldehyde by catalyzing aliphatic primary alcohol dehydrogenation under gas phase condition by using copper oxide as catalyst. The method requires high temperature (300 ℃) and is prone to generate carboxylic acid, resulting in reduced aldehyde selectivity. Patent document CN104707612a discloses a catalyst which is prepared by taking activated alumina, porous silica or activated carbon as a carrier, copper as a main active component, cobalt, nickel, manganese, iron and the like as auxiliary agents and can be used for preparing aldehyde by heterogeneous catalysis of aliphatic primary alcohol dehydrogenation, and can realize high-selectivity dehydrogenation to prepare corresponding aldehyde. However, the method adopts kettle type operation, a complex post-treatment process is required after the reaction, the activity of the catalyst gradually decays along with the increase of the application times, and an additional regeneration process is required. Literature (angel. Chem. Int. Ed.2008, 47, 138-141) reports that the catalyst of hydrotalcite loaded silver nano particles catalyzes aromatic alcohol to prepare corresponding aldehyde by dehydrogenation under mild conditions, and the conversion rate and selectivity reach more than 90%. However, the catalyst has low dehydrogenation activity for catalyzing aliphatic primary alcohols.

Disclosure of Invention

In order to overcome the above disadvantages of the method for preparing aliphatic aldehyde by kettle reaction, the inventor improves the fixed bed reaction process and provides a catalyst system which is particularly suitable for continuous dehydrogenation of aliphatic primary alcohol in a fixed bed and a continuous catalytic process with mild condition. Specifically, the invention comprises the following technical scheme.

The catalyst for preparing aldehyde by dehydrogenation of aliphatic primary alcohol is characterized by being a three-dimensional network structure ruthenium-copper catalyst, which takes a main catalyst ruthenium atom or atom cluster as an active center, takes a copper atom as a cocatalyst, is attached to a carrier, has a three-dimensional network structure, and comprises 0.1-10% of ruthenium element, 0.01-5.0% of copper element and the balance of carrier according to weight percentage.

Preferably, the carrier is silica. When the support is silica, the primary aliphatic alcohol dehydrogenation to aldehyde catalyst may be expressed as x% Ru-y% Cu-SiO ₂ (or as x% Ru-y% Cu/SiO ₂), where x is from 0.1 to 10, preferably from 0.5 to 8, more preferably from 0.8 to 7, more preferably from 1 to 5, and y is from 0.01 to 5.0, preferably from 0.05 to 4.0, more preferably from 0.08 to 3.0, more preferably from 0.1 to 2.0.

The above primary aliphatic alcohols are preferably C3-C10 normal alcohols or isomeric alcohols, such as isoamyl alcohol, n-hexanol, n-heptanol, n-octanol, etc.

In one embodiment, the above primary aliphatic alcohol dehydrogenation to aldehyde catalyst can be prepared by the following method: dissolving ruthenium salt and silicate in alcohol to form transparent sol, aging overnight, pouring supernatant, heating, drying and converting the solid into gel, and roasting to obtain a main catalyst solid with a three-dimensional network structure of x% Ru-SiO ₂ (or expressed as x% Ru/SiO ₂); preparing copper salt aqueous solution, immersing x% Ru/SiO ₂ solid in the copper salt aqueous solution, performing ultrasonic treatment to promote adsorption, filtering, heating, drying and roasting to obtain the x% Ru-y% Cu-SiO ₂ catalyst.

The ruthenium salt may be selected from ruthenium nitrate, ruthenium chloride, ruthenium acetate, ruthenium sulfate, but is not limited thereto; the silicate refers to an orthosilicate, and may be selected from methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate, but is not limited thereto; the alcohol may be selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, t-butanol, 3-pentanol, 2-pentanol, t-pentanol, but is not limited thereto; the copper salt may be selected from copper nitrate, copper chloride, cuprous chloride, copper acetate, copper sulfate, but is not limited thereto.

Preferably, the ruthenium salt is an acetate, the silicate is butyl orthosilicate, the alcohol is ethanol, and the copper salt is copper acetate.

In a specific embodiment, the aliphatic primary alcohol dehydrogenation to aldehyde catalyst can be prepared, for example, by the following methods: dissolving ruthenium acetate and butyl orthosilicate in ethanol to form transparent sol, aging overnight, pouring the supernatant, drying and converting the solid into gel at about 100 ℃, and roasting at about 550 ℃ to obtain a main catalyst with an x% Ru/SiO ₂ three-dimensional network structure; dissolving copper acetate in purified water, immersing x% Ru/SiO ₂ solid in the solution, carrying out ultrasonic treatment at about 60 ℃ for 5 hours to promote adsorption, filtering, drying at about 120 ℃ and roasting at about 500 ℃ to obtain the x% Ru-y% Cu-SiO ₂ catalyst.

The process of forming, aging (or aging, curing) and solidifying the transparent sol into gel enables ruthenium to be uniformly distributed in a silicic acid environment, ruthenium is fixedly distributed in situ in a silicon oxide three-dimensional network after high-temperature roasting, and ruthenium atoms or atom clusters serving as active centers of the catalyst show exposure of the maximum specific surface area. The three-dimensional network structure main catalyst Ru/SiO ₂ is immersed in copper acetate aqueous solution, and ultrasonic treatment further promotes uniform distribution and full adsorption of copper elements in the three-dimensional network structure, copper atoms are also uniformly distributed around ruthenium atoms or atom clusters in the three-dimensional network structure in situ by high-temperature roasting, so that the copper atoms and the ruthenium atoms are matched in a Ru-Cu/SiO ₂ micro-environment/lattice at any position of the catalyst, and the copper atoms and the ruthenium atoms fully play a synergistic effect in the catalytic reaction.

It is to be understood that the terms "about," "about," or "about," when used herein in reference to a numerical feature, mean that the number represented can have an error range or float range of + -10%, + -9%, + -8%, + -7%, + -6%, or + -5%.

The invention also provides a method for preparing aldehyde by continuously dehydrogenating aliphatic primary alcohol, which uses a fixed bed reactor to make the aliphatic primary alcohol as a raw material undergo a gas phase dehydrogenation reaction under the action of the catalyst for preparing aldehyde by dehydrogenating aliphatic primary alcohol, so as to prepare the corresponding aliphatic primary aldehyde.

Preferably, the fixed bed reactor is a tubular fixed bed, and the inner diameter of the tube is preferably 15-25mm.

In a specific embodiment, referring to fig. 2, the fixed bed reactor comprises: raw material (primary aliphatic alcohol) gasifier, reactor, cooler, gas-liquid separation tank, tail gas tank and product tank. The gasifier is provided with a liquid raw material inlet end and a gas raw material outlet end, the outlet end is connected with the reactor inlet end through a pipeline, the outlet end of the reactor is connected with a gas-liquid separation tank through a pipeline, 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 a tail gas tank and then connected with a tail gas treatment device, the liquid phase outlet of the gas-liquid separation tank is connected with a product tank, and a product mixture enters a subsequent separation rectification stage.

In the method, besides the catalyst, the fixed bed is filled with a proper amount of inert carrier, such as quartz sand, inert alumina balls and the like, wherein the filling amount of the inert carrier is 10-150wt% of the filling amount of the catalyst.

In a preferred embodiment, the temperature of the fixed bed gasifier is set to be 200-400 ℃, the temperature of the reactor is set to be 200-400 ℃, and the specific temperature is selected to be suitable for the primary aliphatic alcohol; the volume space velocity of the aliphatic primary alcohol in the fixed bed reactor is 0.2-5.0h ^-1.

The catalyst for preparing the aldehyde by dehydrogenating the aliphatic primary alcohol has the advantages of strong stability, high conversion rate of the aliphatic primary alcohol, good selectivity of the aliphatic primary aldehyde, mild reaction conditions, and wide industrial application prospect, and can be used for preparing the aliphatic primary aldehyde by a continuous dehydrogenation method when applied to a fixed bed reaction device, and overcomes the defects of complex operation and poor selectivity of the traditional kettle type process.

Drawings

FIG. 1 is a flow chart of a process for producing aldehydes by continuous dehydrogenation of primary aliphatic alcohols using a fixed bed reactor according to the present invention. The marks in the figure: 1-raw material tank, 3-gasifier, 5-fixed bed reactor, 6-cooler, 7-gas-liquid separation tank, 10-tail gas tank, 11-product tank, 2,4, 8, 9-valve.

FIG. 2 is a HRMS spectrum of isovaleraldehyde prepared in accordance with the present invention.

FIG. 3 is a HRMS spectrum of n-heptanal prepared in accordance with the present invention.

FIG. 4 is a HRMS spectrum of n-hexanal prepared in accordance with the invention.

FIG. 5 is a HRMS spectrum of n-octanal prepared according to the invention.

Detailed Description

Increasing the conversion of primary aliphatic alcohols, the selectivity and the stability of the product primary aliphatic aldehydes for reuse, and the ability to achieve continuous dehydrogenation reactions are always sought after in the art. For this reason, the present invention has been first conducted on a ruthenium-based catalyst with structural improvement, and experiments have been conducted using inert carriers including molecular sieves, diatomaceous earth, alumina (including calcined α -alumina, high purity alumina, activated alumina, etc.), silica, titania, zirconia, activated carbon, hydrotalcite, kaolin, etc., for fixing ruthenium atoms or clusters as catalytic active centers on the carrier and forming a three-dimensional network structure, which can increase the mechanical strength of the catalyst while expanding the specific surface area. Through repeated comparison, the silicon dioxide is found to be an ideal carrier, and the formed x% Ru/SiO ₂ (wherein x is preferably 1-8) catalyst solid is outstanding in three indexes of raw material conversion rate, product selectivity and repeated use stability.

In the reaction of preparing aliphatic primary aldehyde by dehydrogenating aliphatic primary alcohol catalyzed by x% Ru/SiO ₂, byproduct olefin is always produced. To reduce the occurrence of side reactions, the inventors tried two improvements: firstly, adding ligand compound into catalyst as ligand of ruthenium element, secondly, using ruthenium as main catalyst, and adding other metal elements (such as iron, cerium, copper, tungsten, magnesium, calcium, rhodium, palladium, platinum, iridium, osmium, rhenium, praseodymium, zinc, manganese, cobalt and nickel, etc.) as auxiliary catalyst (auxiliary agent). Through a large number of experimental comparisons, the ideal effect is unexpectedly obtained by using a small amount of copper as a cocatalyst, so that the generation of by-product olefin is obviously reduced, and the conversion rate of primary aliphatic alcohols as raw materials and the selectivity of primary aliphatic aldehydes as products are further improved. The Ru-Cu-SiO ₂ (or Ru-Cu/SiO ₂) catalyst with a three-dimensional network structure is formed by adding copper elements on the basis of x% Ru/SiO ₂ (wherein x is preferably 1-8) catalyst, namely ruthenium-copper catalyst.

For convenience of description, the "aliphatic alcohol dehydrogenation to aldehyde catalyst" of the present invention is sometimes referred to herein simply as "aliphatic alcohol dehydrogenation catalyst", "ruthenium-copper-based catalyst" or "ruthenium-copper catalyst". Correspondingly, the Ru/SiO ₂ catalyst can be referred to as "procatalyst" or "ruthenium catalyst".

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

In an x% Ru-y% Cu-SiO ₂ catalyst, x can range from 0.1 to 10. When the ruthenium content is lower than 0.1%, the catalytic activity of the catalyst is obviously reduced, and the primary aliphatic alcohol is difficult to be rapidly and effectively catalyzed to perform dehydrogenation reaction; when the content is more than 10%, a balance effect of remarkably improving the catalytic activity cannot be obtained, and the production cost of the catalyst may be increased, resulting in a decrease in economy. Preferably x ranges from 0.5 to 8, more preferably from 0.8 to 6, more preferably from 1 to 5.

In an x% Ru-y% Cu-SiO ₂ catalyst, y can range from 0.01 to 5.0. When the copper content is less than 0.1%, the yield of byproduct olefins cannot be reduced, and/or the catalytic efficiency of the main catalyst x% Ru/SiO ₂ is improved; when the content is more than 5%, the catalytic efficiency of the main catalyst Ru/SiO ₂ cannot be further improved, but the selectivity of the aliphatic primary aldehyde is lowered, and even the yield of the byproduct olefin is increased. Preferably y is from 0.05 to 4.0, more preferably from 0.08 to 3.0, more preferably from 0.1 to 2.0

The Ru-Cu-SiO ₂ catalyst needs to be formed into a three-dimensional network structure by adopting a proper catalyst preparation process, and researches show that the performance of the catalyst prepared by sequentially adding ruthenium and copper, particularly the primary aliphatic alcohol conversion rate, is superior to that of the catalyst prepared by simultaneously adding a mixture of ruthenium and copper. Namely, preferably, the ruthenium salt and silicate are formed into gel, and the gel is baked to obtain a Ru/SiO ₂ main catalyst three-dimensional network structure, so that ruthenium atoms or atom clusters are fully dispersed in the network structure to form a catalytic active center; and then carrying copper atoms of a cocatalyst in the network structure in a dispersed manner to finally obtain the Ru-Cu-SiO ₂ catalyst with the three-dimensional network structure, so that the comprehensive performance improvement of the conversion rate of primary aliphatic alcohols of raw materials, the selectivity of primary aliphatic aldehydes of products and the repeated use stability can be obtained.

The three-dimensional network structure enables the catalyst to have certain mechanical strength and endows the catalyst with repeated use stability, so that the catalyst is suitable for being used in a continuous reaction type fixed bed reactor. In one embodiment, the fixed bed reactor is a tubular fixed bed, and the tube inner diameter may be, for example, 15-25mm. Besides Ru-Cu-SiO ₂ catalyst, the fixed bed can be filled with a proper amount of inert carrier such as quartz sand, inert alumina balls and the like, and the filling amount of the inert carrier can be 10-150wt% of the filling amount of the catalyst.

After the inert carrier is filled in the fixed bed, the advancing path of the raw material primary aliphatic alcohol in the tube nest can be prolonged, the residence time of the raw material primary aliphatic alcohol in the reactor can be prolonged, and the reaction raw material and the catalyst can be ensured to be fully contacted, so that the raw material can be fully reacted, and the conversion rate can be improved.

The production apparatus used in the production method of the present invention includes necessary auxiliary devices and post-treatment devices such as a raw material gasifier, a reactor, a cooler, a gas-liquid separation tank, a tail gas tank, a product tank, etc., in addition to the fixed bed reactor. Referring to the example of fig. 1, the production apparatus used includes 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 pipe valves 2, 4, 8, 9.

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

The fixed bed reactor 5 is filled with Ru-SiO ₂ or Ru-Cu-SiO ₂ dehydrogenation catalyst, and the gaseous raw material is subjected to dehydrogenation reaction on the surface and in the internal pore canal of the catalyst to generate aldehyde and hydrogen. However, side reactions, such as dehydration reactions to olefins, may also occur during the reaction.

The cooler 6 is used for cooling the gaseous product output from the reactor 5 to liquefy the primary aliphatic aldehyde so as to separate the gas from the liquid product by a subsequent gas-liquid separation tank.

The gas-liquid separation tank 7 is used for separating gaseous substances and liquid substances, gas is output from a gas phase outlet above and enters the tail gas tank 10, then enters the waste gas treatment system, and liquid is output from a liquid phase outlet below and enters the product tank 11.

The continuous reaction operation flow is as follows: after the reaction system is replaced by nitrogen, raw material primary aliphatic alcohol is metered and then enters a gasifier 3 for gasification, a valve 2 is opened to enable gas to enter a fixed bed reactor 5 filled with catalyst and inert carrier, reaction liquid after dehydrogenation reaction is cooled by a cooler 6 and then enters a gas-liquid separation tank 7, and after gas-liquid separation, the gas enters a tail gas tank 10 through a gas phase outlet above the gas-liquid separation tank. The liquid enters the product tank 11 through a liquid phase outlet below the gas-liquid separation tank, and the temperature of the dehydrogenation reaction can be controlled by adjusting the temperature of the gasifier and the fixed bed reactor in the whole production process.

In the continuous reaction, the temperature of the gasifier can be set to be 200-400 ℃, the temperature of the fixed bed reactor can be set to be 200-400 ℃, and the proper temperature is specifically selected according to different primary aliphatic alcohols, so that the temperature can be determined by a person skilled in the art through limited simple experiments. The reaction temperature is greatly lower than that of the batch kettle type reaction, so that the occurrence of side reaction can be reduced. Meanwhile, the continuous reaction is easier to realize automatic control, and the defect of unstable product quality caused by batch reaction is reduced, so that the quality control is facilitated.

Compared with the prior art, the dehydrogenation catalyst used in the method has the advantages that the active components are uniformly dispersed, the specific surface area is larger, the dehydrogenation catalyst is more fully contacted with the reaction gas, the stability is higher, and the dehydrogenation catalyst can be stably used for thousands of hours; the fixed bed is adopted as the reactor, the structure is simple, the equipment cost can be obviously reduced, the production process is simplified, the energy consumption is reduced, and the production efficiency is improved.

In order to make the invention more comprehensible, preferred embodiments accompanied with the present invention are described in detail below. It will be appreciated by those skilled in the art that the following examples are provided for illustration of the invention and are not intended to be limiting thereof.

Examples

The examples relate to the amounts, amounts and concentrations of various substances, wherein the term "parts" refers to "parts by weight", unless otherwise specified; the percentages mentioned refer to weight percentages unless otherwise indicated.

In the examples, if no specific explanation is given for the experimental operating temperature, this temperature is usually referred to as room temperature (10-30 ℃).

The product analysis method comprises the following steps:

High Resolution Mass Spectrometer (HRMS): agilent 7890B-5977A, auxiliary heating temperature: 280 ℃; ion source temperature: 230 ℃; quadrupole temperature: 150 ℃; acquisition mode: scanning, beginning at 0min, low quality: 29, high quality: 300. chromatographic column: HP-5MS column, 30m 0.25mm,0.25 microns; column incubator: maintaining at 50deg.C for 5min, and heating to 250deg.C at 20deg.C/min for 10min; sample inlet temperature: 250 ℃, split ratio: 100:1; sample injection amount: 0.1 μl.

Gas chromatograph: agilent 7820a, hp-5 column, sample inlet temperature: 150 ℃; split ratio: 50:1; carrier gas flow rate: 2ml/min; heating program: maintaining at 50deg.C for 5min, heating to 90deg.C at 10deg.C/min, and maintaining for 5min; heating to 160 ℃ at 10 ℃/min, and keeping for 5min; finally, the temperature is increased to 280 ℃ at 30 ℃ per minute, and the temperature is kept for 6 minutes. Detector temperature: 280 ℃.

Example 1: method for preparing isovaleraldehyde by catalyzing isoamyl alcohol dehydrogenation through ruthenium catalyst

1.1 Catalyst preparation

Ruthenium catalyst x% Ru-SiO ₂:

Dissolving a certain amount of ruthenium acetate and butyl orthosilicate in ethanol to form transparent sol, aging overnight, pouring the supernatant, drying the solid at 100 ℃ to convert the solid into gel, and roasting at 550 ℃ to obtain the x% Ru/SiO ₂ catalyst.

Ruthenium copper catalyst x% Ru-y% Cu-SiO ₂:

Copper acetate is dissolved in purified water according to a proportion, an x% Ru/SiO ₂ catalyst is immersed in a copper acetate solution, heating and ultrasonic treatment are carried out at 60 ℃ for 5 hours to promote adsorption, filtering, drying at 120 ℃ and roasting at 500 ℃ are carried out, and the x% Ru-y% Cu-SiO ₂ catalyst is obtained.

1.2 Fixed bed continuous reaction

The metal ruthenium loading is regulated to prepare 1% Ru/SiO ₂ catalyst with x=1, and the catalyst is crushed and pressed into tablets to obtain particles with the diameter of 6 mm. 20g of the formed catalyst and 10g of quartz sand are filled into a fixed bed reactor, after nitrogen replacement, the temperature of the gasifier and the reactor is raised to 250 ℃, and the volume space velocity of isoamyl alcohol is 3.6h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The results were as follows: the isoamyl alcohol conversion was 90.7%, the selectivity of the isoamyl aldehyde was 95.9%, and the main byproduct was isoamylene, approximately 3.0%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₅H₁₀ O, found 86 (FIG. 2).

Example 2: method for preparing isovaleraldehyde by catalyzing isoamyl alcohol dehydrogenation through ruthenium-copper catalyst

2.1 According to the method of example 1.1, the loading of metallic ruthenium and copper is adjusted to prepare a ruthenium-copper catalyst with x=3 and y=0.4, namely 3% Ru-0.4% Cu/SiO ₂, which is applied to the preparation of isovaleraldehyde by catalyzing the dehydrogenation of isoamyl alcohol. The catalyst was tabletted to give catalyst particles 6mm in diameter. 20g of the formed catalyst and 20g of the inert alumina balls are filled into a fixed bed reactor, and after nitrogen replacement, the temperature of the gasifier and the reactor is raised to 300 ℃, and the volume space velocity of isoamyl alcohol is maintained to be 3.6h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The isoamyl alcohol conversion was 95.6%, the selectivity of the isoamyl aldehyde was 98.5%, and the main byproduct was isoamylene, about 0.9%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₅H₁₀ O, found 86.

2.2 Adjusting the loadings of metallic ruthenium and copper, ruthenium-copper catalysts of different x and y were prepared, respectively, and isopentyl aldehyde was prepared by catalyzing the dehydrogenation of isoamyl alcohol in the same manner as in example 2.1, and the results are shown in Table 1.

Table 1, examples of catalysts x% Ru-y% Cu-SiO ₂ for catalyzing dehydrogenation of isoamyl alcohol to prepare isovaleraldehyde

Sequence number	x	y	Temperature (DEG C)	Conversion%	Selectivity%	Isopentene%
							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

As can be seen from Table 1, compared with Ru-SiO ₂ serving as a ruthenium catalyst, the ruthenium-copper series catalyst Ru-Cu-SiO ₂ serving as a ruthenium-copper series catalyst with x=1-5 and y=0.2-2.0 has the advantages that the raw material conversion rate and the product selectivity of the isoamyl alcohol preparation method are improved to a certain extent, and the byproduct yield is obviously reduced.

Example 3: preparation of n-heptanal by catalyzing dehydrogenation of n-heptanol by ruthenium catalyst

The loading of metallic ruthenium was adjusted as in example 1.1 to produce a 3% ru/SiO ₂ catalyst with x=3, which was used to catalyze the dehydrogenation of n-heptanol to produce n-heptanal. The catalyst is crushed and pressed into tablets to obtain particles with the diameter of 6 mm. 40g of the shaped catalyst and 40g of inert alumina balls are filled into a fixed bed reactor, and after nitrogen replacement, the temperature of the gasifier and the reactor is raised to 280 ℃, and the volume space velocity of the n-heptanol is 3.1h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The results were as follows: the conversion of n-heptanol was 92.6%, the selectivity of n-heptanal was 93.9%, and the main by-product was an olefin produced by dehydration, which was about 1.2%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₇H₁₄ O, found 114 (FIG. 3).

Example 4: preparation of n-heptanal by catalyzing dehydrogenation of n-heptanol by ruthenium-copper catalyst

The ruthenium and copper loadings were adjusted as in example 1.1 to produce a ruthenium copper catalyst of x=3, y=1.0% ru-1.0% cu/SiO ₂ for catalyzing the dehydrogenation of n-hexanol. The prepared catalyst is crushed and pressed into tablets to obtain catalyst particles with the diameter of 6 mm. 50g of the shaped catalyst and 20g of quartz sand are filled into a fixed bed reactor, the temperature of the gasifier and the reactor is raised to 280 ℃ after nitrogen replacement, and the volume space velocity of the n-hexanol is maintained to be 3.1h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The conversion of n-hexanol was 96.0%, the selectivity of n-hexanal was 97.8%, and the by-product olefin was about 0.2%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₇H₁₄ O, found 114.

Example 5: preparation of hexanal by dehydrogenation of n-hexanol under catalysis of ruthenium catalyst

The loading of metallic ruthenium was adjusted as in example 1.1 to produce a 5% ru/SiO ₂ catalyst with x=5, which was used to catalyze the dehydrogenation of n-hexanol to produce n-hexanal. The prepared catalyst is crushed and pressed into tablets to obtain catalyst particles with the diameter of 6 mm. 30g of the shaped catalyst and 10g of quartz sand are filled into a fixed bed reactor, the temperature of the gasifier and the reactor is raised to 300 ℃ after nitrogen replacement, and the volume space velocity of the n-hexanol is maintained to be 3.0h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The conversion of n-hexanol was 85.2%, the selectivity of aldehyde was 95.8%, and the main by-product was the alcohol dehydration product olefin, which was about 1.1%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₆H₁₂ O, found 100 (FIG. 4).

Example 6: preparation of hexanal by dehydrogenation of n-hexanol under catalysis of ruthenium-copper catalyst

The loading of metallic ruthenium and copper was adjusted as in example 1.1 to produce a 5% ru-1% cu/SiO ₂ catalyst with x=5, y=1 for catalyzing the dehydrogenation of n-hexanol. The prepared catalyst is crushed and pressed into tablets to obtain catalyst particles with the diameter of 6 mm. 50g of the shaped catalyst and 20g of quartz sand are filled into a fixed bed reactor, the temperature of the gasifier and the reactor is raised to 300 ℃ after nitrogen replacement, and the volume space velocity of the n-hexanol is maintained to be 2.5h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The conversion of n-hexanol was 95.0%, the selectivity of n-hexanal was 97.6%, and the by-product olefin was about 0.2%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₆H₁₂ O, found 100.

Example 7: preparation of n-octyl aldehyde by catalyzing n-octyl alcohol dehydrogenation with ruthenium catalyst

The loading of metallic ruthenium was adjusted as in example 1.1 to prepare a 3% ru/SiO ₂ catalyst with x=3 for the catalytic dehydrogenation of n-octanol to make n-octanal. The prepared catalyst is crushed and pressed into tablets to obtain catalyst particles with the diameter of 6 mm. 20g of the formed catalyst and 30g of quartz sand are filled into a fixed bed reactor, the temperature of the gasifier and the reactor is raised to 280 ℃ after nitrogen replacement, and the volume space velocity of n-octanol is maintained to be 3.5h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The conversion of n-octanol was 88.3%, the selectivity of aldehyde was 93.1%, and the main by-product was alcohol dehydration product olefin, approximately 1.8%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₈H₁₆ O, found 128 (FIG. 5).

Example 8: preparation of n-octyl aldehyde by catalyzing n-octyl alcohol dehydrogenation with ruthenium-copper catalyst

The metal ruthenium and copper loadings were adjusted as in example 1.1 to produce a 3% ru-2% cu/SiO ₂ catalyst with x=3, y=2 for catalyzing n-octanol dehydrogenation reactions. The prepared catalyst is crushed and pressed into tablets to obtain catalyst particles with the diameter of 6 mm. 35g of the shaped catalyst was charged into a fixed bed reactor, and after nitrogen substitution, both the gasifier and the reactor were warmed to 280℃and the volume space velocity of n-octanol was maintained at 3.0h ^-1. After one hour of reaction, sampling was started and the product composition was analyzed by gas chromatography. The conversion of n-octanol was 93.1%, the selectivity of n-octanal was 97.6%, and the by-product olefin was about 0.8%. Characterization of the product: HRMS m/z: [ M+H ] ⁺Calcd for C₈H₁₆ O, found 128.

The embodiment shows that the catalysts Ru/SiO ₂ and Ru-Cu/SiO ₂ with three-dimensional network structures, especially the catalyst Ru-Cu/SiO ₂, have strong stability, high raw material conversion rate for catalyzing the dehydrogenation reaction of aliphatic primary alcohol, good product selectivity, and mild reaction conditions, are suitable for mass production, and can be applied to a fixed bed reaction device to realize a continuous dehydrogenation method for preparing aliphatic aldehyde.

Although the technical scheme of the invention is described above by taking isoamyl alcohol, n-hexanol, n-heptanol and n-octanol as examples, the technical scheme of the invention is also applicable to other aliphatic primary alcohol dehydrogenation aldehyde preparation methods according to the disclosure of the invention, and the technical scheme is obvious to those skilled in the art. Accordingly, various changes and modifications may be made by one skilled in the art without departing from the spirit of the invention, and equivalents of such changes and modifications may be resorted to, falling within the scope of the invention.

Claims

1. The catalyst for preparing aldehyde by dehydrogenation of aliphatic primary alcohol is characterized by being 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 balance of carrier according to weight percentage.

2. The catalyst for the dehydrogenation of aliphatic alcohols to aldehydes according to claim 1, wherein the carrier is silica, and the catalyst for the dehydrogenation of aliphatic alcohols to aldehydes is represented by x% Ru-y% Cu-SiO ₂, wherein x is 0.1 to 10, and y is 0.01 to 5.0.

3. The catalyst for the dehydrogenation of aliphatic primary alcohols to aldehydes according to claim 1, wherein said aliphatic primary alcohols are C3-C10 normal alcohols or isopolyols.

4. The catalyst for the dehydrogenation of aliphatic primary alcohols to aldehydes according to claim 1, which is prepared by the following method:

dissolving ruthenium salt and silicate in alcohol to form transparent sol, aging overnight, pouring supernatant, heating, drying, converting solid into gel, and roasting to obtain a main catalyst solid with an x% Ru/SiO ₂ three-dimensional network structure;

Preparing copper salt aqueous solution, immersing x% Ru/SiO ₂ solid in the copper salt aqueous solution, performing ultrasonic treatment to promote adsorption, filtering, heating, drying and roasting to obtain the x% Ru-y% Cu-SiO ₂ catalyst.

5. The catalyst for the dehydrogenation of aliphatic alcohols to aldehydes according to claim 4, wherein the ruthenium salt is selected from the group consisting of ruthenium nitrate, ruthenium chloride, ruthenium acetate, ruthenium sulfate; the silicate refers to orthosilicate, and is 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.

6. The catalyst for the dehydrogenation of aliphatic primary alcohols to aldehydes according to claim 4, wherein said ruthenium salt is acetate, said silicate is butyl orthosilicate, said alcohol is ethanol, and said copper salt is copper acetate.

7. A method for preparing aldehyde by continuously dehydrogenating aliphatic primary alcohol, which is characterized in that a fixed bed reactor is used for carrying out gas-phase dehydrogenation reaction on the aliphatic primary alcohol under the action of the catalyst for preparing aldehyde by dehydrogenating aliphatic primary alcohol according to any one of claims 1-6, so as to prepare the corresponding aliphatic primary aldehyde.

8. The process according to claim 7, wherein the fixed bed reactor is a tube-type fixed bed, the tube inner diameter is preferably 15-25mm.

9. The method of claim 7, wherein the fixed bed is filled with an inert carrier in addition to the catalyst, and the inert carrier is filled in an amount of 10 to 150wt% of the catalyst.

10. The method of claim 7, wherein the fixed bed has a reaction temperature of 200 to 400 ℃; the volume space velocity of the aliphatic primary alcohol in the fixed bed reactor is 0.2-5.0h ^-1.