A method for catalytically preparing isopropylamine from isopropanol

Abstract

The present invention discloses a method for efficiently catalyzing the preparation of isopropylamine from isopropyl alcohol. The catalyst used in this method is prepared by a preparation method including the following steps: 1) subjecting a support to acid treatment and / or alkali treatment to obtain a treated support, the support containing silicon and / or aluminum elements; 2) loading an oxide of an active metal component on the treated support to obtain a catalyst precursor; 3) performing hydrophobic modification on the catalyst precursor with a silane coupling agent, and obtaining the catalyst after reduction. By subjecting the support to acid treatment and / or alkali treatment, and performing hydrophobic modification treatment with a silane coupling agent after loading the active component, the present invention can form an anhydrous environment similar around the active component of the catalyst, which can significantly improve the conversion rate of isopropyl alcohol.

Description

Technical Field

[0001] The present invention relates to a method for efficiently catalyzing the preparation of isopropylamine from isopropyl alcohol. Background Art

[0002] Aliphatic amines are organic derivatives of ammonia and belong to a kind of organic amines. They are important synthetic raw materials for many chemical products and are widely used in the fields of pesticides, pharmaceuticals, dyes, etc. In the industrial production process, alcohols or ketones are usually used as production raw materials. The reaction mechanism is generally considered that the alcohol is dehydrogenated to form a carbonyl group, or the carbonyl group in the ketone compound reacts with ammonia to form an imine, and then the imine is hydrogenated to form an aliphatic amine. Isopropylamine is an important raw material for the production of pesticides such as atrazine, isofenphos-methyl, and buprofezin, etc., and can also be used for the preparation of isopropylamine salt of dodecylbenzenesulfonic acid in detergents. Moreover, isopropylamine is also widely used in the rubber industry and the pharmaceutical industry.

[0003] At present, there are mainly two reaction routes for the industrial production of isopropylamine. One of them is the hydrogenation amination of acetone to synthesize isopropylamine. However, acetone is prone to hydrogenation to form by-products under the action of a catalyst, resulting in low reaction selectivity and affecting production efficiency. The other reaction route is to use isopropyl alcohol as a raw material to prepare isopropylamine. The product composition of this process route is simple, and the products are usually mono-isopropylamine and / or di-isopropylamine. The reaction selectivity of mono-isopropylamine and / or di-isopropylamine (collectively referred to as isopropylamine) is high. However, there is a reaction equilibrium in the process of preparing isopropylamine from isopropyl alcohol. When the product is di-isopropylamine, the reaction equilibrium effect is more significant, resulting in a low conversion rate of isopropyl alcohol. In addition, the raw material isopropyl alcohol, the generated water, and di-isopropylamine will form a ternary azeotropic system, increasing the energy consumption for product separation.

[0004] Patent CN115819246B discloses a method for preparing di-isopropylamine. Using Ni / Al2O3 as a catalyst, isopropyl alcohol and ammonia as raw materials, the reaction is carried out in a fixed-bed adiabatic reactor under a hydrogen atmosphere. At the same time, by returning the isopropylamine in the product as a raw material, the conversion rate of this reaction can reach more than 81.72%. However, this conversion rate is still relatively low and the process is complex.

[0005] How to efficiently improve the conversion rate of isopropyl alcohol when synthesizing isopropylamine from isopropyl alcohol is a difficult point in this process route. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an improved method for preparing isopropylamine from isopropyl alcohol in view of the shortcomings and deficiencies of the prior art, which can improve the conversion rate of isopropyl alcohol.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing isopropylamine from isopropanol, using isopropanol and ammonia as raw materials, reacting in the presence of a catalyst to produce the isopropylamine, and the catalyst is prepared by a preparation method including the following steps: 1) subjecting a support to acid treatment and / or alkali treatment to obtain a treated support, and the support contains silicon and / or aluminum elements; 2) loading an oxide of an active metal component on the treated support to obtain a catalyst precursor; 3) hydrophobically modifying the catalyst precursor with a silane coupling agent and obtaining the catalyst after reduction.

[0009] In the present invention, isopropylamine includes mono-isopropylamine and di-isopropylamine, and the two are collectively referred to as isopropylamine. The reaction product may contain one of them or may contain both at the same time.

[0010] In step 1), during acid treatment, the acid reacts with aluminum to remove part of the aluminum from the support; during alkali treatment, the alkali reacts with silicon to remove part of the silicon from the support. The treated support forms a corresponding pore structure, and in this pore structure, Si-OH or Al-OH chemical bond structures are generated, that is, hydroxyl groups are exposed.

[0011] In some embodiments, the support is selected from one or a combination of silica-alumina gel, silica, ZSM-5 molecular sieve, and Beta molecular sieve.

[0012] In some embodiments, the acid used for the acid treatment is selected from one or a combination of citric acid, oxalic acid, and acetic acid.

[0013] In some embodiments, the alkali used for the alkali treatment is selected from one or both of sodium hydroxide and potassium hydroxide.

[0014] In some embodiments, the support is silica-alumina gel or ZSM-5 molecular sieve, and in step 1), the support is subjected to acid treatment and / or alkali treatment. Both silica-alumina gel and ZSM-5 molecular sieve contain silicon dioxide and aluminum oxide, and can be subjected to separate acid treatment or alkali treatment, or both treatments can be carried out simultaneously.

[0015] In some embodiments, the support is silica, and in step 1), the support is subjected to alkali treatment.

[0016] In some embodiments, the support is Beta molecular sieve, and in step 1), the support is subjected to acid treatment.

[0017] In some embodiments, the temperature of the acid treatment and / or alkali treatment is 50-60°C.

[0018] In some embodiments, the time of the acid treatment and / or alkali treatment is 2-6 h.

[0019] In some embodiments, the acid treatment is achieved by immersing the carrier in an aqueous solution of an acid.

[0020] In some embodiments, the base treatment is achieved by immersing the carrier in an aqueous solution of a base.

[0021] In some embodiments, the molar concentration of the aqueous solution of the acid is 0.1 - 0.5 mol / L.

[0022] In some embodiments, the molar concentration of the aqueous solution of the base is 0.05 - 0.1 mol / L.

[0023] In some embodiments, in step 2), the active component is loaded onto the treated carrier by an impregnation method or a co - precipitation method.

[0024] In some embodiments, in the case of the impregnation method, a water - soluble salt solution of the active metal component is impregnated into the treated carrier. After the impregnation, the obtained solid is calcined to obtain a catalyst precursor. The number of impregnation times can be one or multiple. When multiple times, the impregnation and calcination steps are repeated. The impregnation method can be the equal - volume impregnation method.

[0025] In some embodiments, the co - precipitation method refers to first impregnating the treated carrier with an aqueous solution of a water - soluble salt of the active component, then adding a precipitant for precipitation, and finally calcining.

[0026] In some embodiments, the precipitant is selected from sodium hydroxide, sodium carbonate, etc.

[0027] In some embodiments, the pH value during precipitation is 9 - 10.

[0028] In some embodiments, by mass percentage, the catalyst comprises 10% - 27% of the active metal component and 73% - 90% of the treated carrier.

[0029] In some embodiments, the active metal component is selected from Ni, Co, Cu, Cu / Pt, Cu / Ni or Ni / Pt, wherein Cu / Pt is a combination of Cu and Pt, Cu / Ni is a combination of Cu and Ni, and Ni / Pt is a combination of Ni and Pt.

[0030] In some embodiments, in Cu / Pt or Ni / Pt, the Pt accounts for 0.5% - 5% of the mass percentage of the catalyst; in Cu / Ni, the Cu accounts for 10% - 15% of the mass percentage of the catalyst.

[0031] In some embodiments, the silane coupling agent is (R1) n Si(OR2) m, wherein, R1 is independently selected from methyl, ethyl or propyl, R2 is independently selected from methyl or ethyl, n is 1, 2 or 3, m is 1, 2 or 3, and n + m = 4.

[0032] In some embodiments, the hydrophobic modification is achieved by impregnating a solution of the silane coupling agent into the catalyst precursor.

[0033] In some embodiments, the solution is an aqueous solution or an alcohol solution. The alcohol is, for example, ethanol.

[0034] In some embodiments, the mass percentage concentration of the solution is 5% - 10%.

[0035] In some embodiments, the mass of the silane coupling agent accounts for 5% - 10% of the mass of the catalyst precursor.

[0036] In some embodiments, the temperature of the hydrophobic modification is 60 - 80 °C.

[0037] In some embodiments, the time of the hydrophobic modification is 4 - 12 h.

[0038] In some embodiments, the reduction is carried out in a hydrogen atmosphere. The reduction can be in-situ reduction, that is, the reduction is carried out in the reactor for preparing isopropylamine from isopropanol, and the catalytic reaction is carried out immediately after the reduction. This can avoid the surface oxidation of the active metal components of the catalyst.

[0039] In some embodiments, the temperature of the reduction is 350 - 550 °C.

[0040] In some embodiments, the time of the reduction is 4 - 6 h.

[0041] In some embodiments, the mass space velocity of the isopropanol is 0.5 - 3 h -1 。

[0042] In some embodiments, the temperature of the reaction is 165 - 195 °C.

[0043] In some embodiments, the pressure of the reaction is 1 - 2 MPa.

[0044] In some embodiments, the molar ratio of isopropanol to ammonia is 1:1 - 7.

[0045] In some embodiments, the reaction is carried out in a hydrogen atmosphere, and the molar ratio of isopropanol to hydrogen is 1:1 - 3.

[0046] In some embodiments, isopropylamine is used to replace ammonia, and the molar ratio of isopropanol to isopropylamine is 1:1.1 - 1:1.5. Isopropylamine will also react with ammonia to synthesize diisopropylamine. The reaction raw material of the present application can be isopropanol or a mixture of isopropanol and isopropylamine.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] In the prior art, there is a reaction equilibrium in the process of preparing isopropylamine from isopropanol, and the conversion rate of isopropanol is relatively low. In the present invention, the carrier is first subjected to acid treatment or alkali treatment. During acid treatment, part of the Al in the carrier is removed by reaction, the Si - O - Al bond in the carrier is broken between O and Al, and a pore structure is formed in the corresponding part of Al, and a Si - OH structure is generated in this structure; during alkali treatment, part of the Si in the carrier is removed by reaction, the Si - O - Al bond in the carrier is broken between O and Si, and a pore structure is formed in the corresponding part of Si, and an Al - OH structure is generated in this structure; then the carrier is loaded with the oxide of the active metal component, and finally it is subjected to hydrophobic modification. The silane coupling agent for hydrophobic modification will hydrolyze to generate a Si - OH structure, and the Si - OH or Al - OH in the pore structure of the carrier will undergo a condensation reaction with the Si - OH generated by the hydrolysis of the hydrophobic modifier, so that the group around the pore structure is modified into a hydrophobic group, and the active component is basically loaded in the pore structure. Therefore, after hydrophobic modification, the environment around the active component in the catalyst is a hydrophobic environment, providing an environment similar to anhydrous on the surface of the active component of the catalyst. This environment repels water and promotes the departure of the water generated during the process of preparing isopropylamine from isopropanol, making the equilibrium reaction shift forward, and thus significantly improving the conversion rate of isopropanol.

[0049] By subjecting the carrier to acid treatment and / or alkali treatment, and then performing hydrophobic modification treatment with a silane coupling agent after loading the active component, the present invention can form an environment similar to anhydrous around the active component of the catalyst, and can significantly improve the conversion rate of isopropanol.

[0050] The method of the present invention can achieve the improvement of the conversion rate of isopropanol while ensuring a high reaction selectivity of isopropylamine, and the conversion rate of isopropanol is as high as more than 95%. Detailed implementation mode

[0051] The present invention will be further described below in conjunction with embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions adopted in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are the conventional conditions in the industry. The technical features involved in each implementation mode of the present invention can be combined with each other as long as they do not conflict with each other. Example 1

[0052] This embodiment provides a catalyst and uses it for the preparation of isopropylamine from isopropanol, specifically as follows:

[0053] 1) Support modification:

[0054] The silica-alumina gel powder is impregnated in a 0.5 mol / L aqueous citric acid solution and impregnated at 50 °C for 6 h. After the impregnation, the silica-alumina gel is washed clean to obtain the treated silica-alumina gel powder.

[0055] 2) Metal loading:

[0056] The treated silica-alumina gel powder is impregnated in a 1 mol / L aqueous cobalt nitrate solution. After the impregnation, the silica-alumina gel support is dried and calcined at 500 °C for 6 h to obtain the Co catalyst impregnated once. The second impregnation is repeated, followed by drying and calcination to obtain the Co2O3 / silica-alumina gel catalyst.

[0057] 3) Hydrophobic modification of the catalyst:

[0058] The Co2O3 / silica-alumina gel catalyst is impregnated in an ethanol aqueous solution of methyltriethoxysilane (mass percentage concentration is 6%). The mass of methyltriethoxysilane accounts for 10% of the mass of the Co2O3 / silica-alumina gel catalyst. It is heated at 60 °C for 4 h, and then the liquid is evaporated to dryness to obtain the hydrophobically modified Co2O3 / silica-alumina gel catalyst, in which the cobalt mass content measured by ICP is 20%.

[0059] 4) Catalyst evaluation, synthesis reaction:

[0060] The hydrophobically modified Co2O3 / silica-alumina gel catalyst is granulated into 20-40 mesh, and 4 g of the catalyst is placed into the catalyst evaluation device. First, it is reduced at 500 °C for 6 h (online reduction of the catalyst), and then the temperature is lowered to the reaction temperature for reaction. The raw material is isopropanol, and then it is fed according to the ratio of the raw material mass space velocity of 1 / h, the molar ratio of hydrogen:isopropanol = 2, and ammonia:isopropanol = 5. The reaction temperature is 175 °C, and the reaction pressure is 1 MPa for testing. The test results are that the isopropanol conversion rate is 95.1%, the selectivity of mono-isopropylamine is 93.0%, and the selectivity of di-isopropylamine is 6.1%. Example 2

[0061] This embodiment provides a catalyst and uses it for the preparation of isopropylamine from isopropanol, specifically as follows:

[0062] 1) Support modification:

[0063] The silica is impregnated in a 0.05 mol / L aqueous sodium hydroxide solution and impregnated at 50 °C for 6 h. After the impregnation, the silica is washed clean to obtain the treated silica.

[0064] 2) Metal loading:

[0065] The processed silica was added to an aqueous solution of nickel nitrate at 1 mol / L. After stirring for 2 h, an aqueous solution of sodium carbonate was added dropwise to the above nickel nitrate aqueous solution until the pH value of the mixed solution reached 10, and it was kept overnight at 60 °C. Then the aged Ni catalyst was taken out and calcined at 450 °C for 6 h to obtain NiO / SiO2.

[0066] 3) Hydrophobic modification of the catalyst:

[0067] NiO / SiO2 was impregnated in an aqueous ethanol solution of ethyltrimethoxysilane (mass percentage concentration: 8%), and the mass of ethyltrimethoxysilane accounted for 10% of the mass of NiO / SiO2. It was heated at 70 °C for 6 h, and then the liquid was evaporated to dryness to obtain the hydrophobically modified NiO / SiO2 catalyst, in which the mass content of Ni measured by ICP was 25%.

[0068] 4) Catalyst evaluation, synthesis reaction:

[0069] The hydrophobically modified NiO / SiO2 catalyst was granulated into 20 - 40 mesh, and 4 g of the catalyst was placed into a catalyst evaluation device. First, it was reduced at 500 °C for 6 h (online reduction of the catalyst), and then the temperature was lowered to the reaction temperature for reaction. The raw materials were a mixture of isopropanol and isopropylamine, with the molar ratio of isopropanol:isopropylamine = 1:1.2. Then, it was tested according to a raw material mass space velocity of 0.5 / h, a molar ratio of hydrogen:isopropanol = 2, a reaction temperature of 185 °C, and a reaction pressure of 1.5 MPa. The test results showed an isopropanol conversion rate of 96.0% and a diisopropylamine selectivity of 99.0%. Example 3

[0070] This example provides a catalyst and uses it for the preparation of isopropylamine from isopropanol, specifically as follows:

[0071] 1) Support modification:

[0072] ZSM-5 molecular sieve was impregnated in a 0.1 mol / L aqueous citric acid solution and impregnated at 50 °C for 6 h. After the impregnation, the ZSM-5 molecular sieve was washed clean to obtain the processed ZSM-5 molecular sieve.

[0073] 2) Metal loading:

[0074] The processed ZSM-5 molecular sieve was impregnated in an aqueous solution of copper nitrate at 1 mol / L. After the impregnation, the ZSM-5 molecular sieve was dried to obtain a Cu catalyst impregnated once. The Cu catalyst impregnated once was calcined at 500 °C for 4 h to obtain CuO / ZSM-5. The obtained CuO / ZSM-5 after calcination was impregnated with an equal volume of an aqueous solution of chloroplatinic acid. After the impregnation, it was calcined at 500 °C for 4 h to obtain CuO-PtO2 / ZSM-5.

[0075] 3) Hydrophobic modification of the catalyst:

[0076] CuO-PtO2 / ZSM-5 was impregnated in an aqueous ethanol solution of diethyldimethoxysilane (mass percentage concentration was 10%). The mass of diethyldimethoxysilane accounted for 5% of the mass of CuO-PtO2 / ZSM-5. It was refluxed at 80 °C for 8 h. After suction filtration, the hydrophobic modified CuO-PtO2 / ZSM-5 catalyst was obtained, in which the mass content of copper measured by ICP was 10%, and the mass content of Pt was 0.5%.

[0077] 4) Catalyst evaluation, synthesis reaction:

[0078] The hydrophobic modified CuO-PtO2 / ZSM-5 catalyst was granulated into 20-40 mesh, and 4 g of the catalyst was put into a catalyst evaluation device. First, it was reduced at 500 °C for 6 h (online reduction of the catalyst), and then the temperature was lowered to the reaction temperature for reaction. The raw material was isopropanol. Then, it was fed according to the ratio of raw material mass space velocity 1 / h, molar ratio of hydrogen:isopropanol = 1, and ammonia:isopropanol = 1. The reaction temperature was 165 °C and the reaction pressure was 1.5 MPa for testing. The test results were that the conversion rate of isopropanol was 95.6%, the selectivity of isopropylamine was 68.3%, and the selectivity of diisopropylamine was 30.9%. In this example, the selectivity of diisopropylamine was relatively high because the molar ratio of ammonia to isopropanol in the raw material was relatively low. Both isopropylamine and diisopropylamine are industrially available. Example 4

[0079] This example provides a catalyst and uses it for the preparation of isopropylamine from isopropanol, specifically as follows:

[0080] 1) Support modification:

[0081] The silica-alumina gel was impregnated in an aqueous acetic acid solution at 0.1 mol / L and impregnated at 60 °C for 6 h. After the impregnation, the silica-alumina gel was washed clean to obtain the treated silica-alumina gel.

[0082] 2) Metal loading:

[0083] The processed silica-alumina gel was impregnated in an aqueous solution of copper nitrate at 1 mol / L. After the impregnation, the silica-alumina gel was dried to obtain the Cu catalyst impregnated once. The Cu catalyst impregnated once was calcined at 500 °C for 4 h to obtain CuO / silica-alumina gel. The CuO / silica-alumina gel obtained after calcination was impregnated in an aqueous solution of nickel nitrate at 0.8 mol / L. After the impregnation, the silica-alumina gel was dried to obtain the impregnated CuNi catalyst, and it was calcined at 500 °C for 4 h to obtain CuO-NiO / silica-alumina gel.

[0084] 3) Hydrophobic modification of the catalyst:

[0085] The CuO-NiO / silica-alumina gel was impregnated in an aqueous ethanol solution of triethylmethoxysilane (mass percentage concentration was 5%), and the mass of triethylmethoxysilane accounted for 5% of the mass of CuO-NiO / silica-alumina gel. It was refluxed at 70 °C for 10 h. After suction filtration, the hydrophobic modified CuO-NiO / silica-alumina gel catalyst was obtained. By ICP measurement, the mass content of copper in it was 10%, and the mass fraction of Ni was 8%.

[0086] 4) Catalyst evaluation, synthesis reaction:

[0087] The hydrophobic modified CuO-NiO / silica-alumina gel catalyst was granulated into 20-40 mesh, and 4 g of the catalyst was put into the catalyst evaluation device. First, it was reduced at 500 °C for 6 h (online reduction of the catalyst), and then the temperature was lowered to the reaction temperature for reaction. The raw material was isopropanol, and then it was fed according to the ratio of the mass space velocity of the raw material of 0.8 / h, the molar ratio of hydrogen:isopropanol = 1, and ammonia:isopropanol = 2. The reaction was tested at a reaction temperature of 165 °C and a reaction pressure of 1.5 MPa. The test results were that the conversion rate of isopropanol was 97.1%, the selectivity of isopropylamine was 88.3%, and the selectivity of diisopropylamine was 10.9%. Example 5

[0088] This example provides a catalyst and uses it for the preparation of isopropylamine from isopropanol, specifically as follows:

[0089] 1) Support modification:

[0090] The Beta zeolite was impregnated in an aqueous solution of oxalic acid at 0.1 mol / L and impregnated at 60 °C for 6 h. After the impregnation, the Beta zeolite was washed clean to obtain the processed Beta zeolite.

[0091] 2) Metal loading:

[0092] The processed Beta zeolite was impregnated in an aqueous solution of nickel nitrate at 1 mol / L. After the impregnation, the Beta zeolite was dried to obtain the Ni catalyst impregnated once. The Ni catalyst impregnated once was calcined at 500 °C for 4 h to obtain NiO / Beta. The obtained NiO / Beta after calcination was impregnated with an aqueous solution of chloroplatinic acid in an equal volume, and after the impregnation, it was calcined at 500 °C for 4 h to obtain NiO-PtO2 / Beta.

[0093] 3) Hydrophobic modification of the catalyst:

[0094] NiO-PtO2 / Beta was impregnated in an ethanol aqueous solution of triethylmethoxysilane (mass percentage concentration was 5%), the mass of triethylmethoxysilane accounted for 5% of the mass of NiO-PtO2 / Beta, and it was refluxed at 70 °C for 10 h. After suction filtration, the hydrophobically modified NiO-PtO2 / Beta catalyst was obtained. By ICP measurement, the mass content of Ni in it was 10%, and the mass fraction of Pt was 0.5%.

[0095] 4) Catalyst evaluation, synthesis reaction:

[0096] The hydrophobically modified NiO-PtO2 / Beta catalyst was granulated into 20-40 mesh, and 4 g of the catalyst was put into the catalyst evaluation device. First, it was reduced at 500 °C for 6 h (online reduction of the catalyst), and then the temperature was lowered to the reaction temperature for reaction. The raw material was isopropanol, and then it was fed according to the ratio of the mass space velocity of the raw material of 0.8 / h, the molar ratio of hydrogen:isopropanol = 1, and ammonia:isopropanol = 4. The reaction was tested at a reaction temperature of 165 °C and a reaction pressure of 1.5 MPa. The test results were that the conversion rate of isopropanol was 98.1%, the selectivity of isopropylamine was 93.3%, and the selectivity of diisopropylamine was 6.2%. Example 6

[0097] This example provides a catalyst and uses it for the preparation of isopropylamine from isopropanol, specifically as follows:

[0098] 1) Support modification:

[0099] The silica-alumina gel was impregnated in an aqueous solution of potassium hydroxide at 0.05 mol / L, and impregnated at 60 °C for 2 h. After the impregnation, the silica-alumina gel was washed clean and then impregnated in an aqueous solution of acetic acid at 0.1 mol / L, and impregnated at 60 °C for 4 h. After the impregnation, the silica-alumina gel was washed clean to obtain the processed silica-alumina gel.

[0100] 2) Metal loading:

[0101] The processed silica-alumina gel was added to an aqueous solution of copper nitrate at 1 mol / L. After stirring for 2 h, an aqueous solution of sodium hydroxide was added dropwise to the above aqueous solution of copper nitrate until the pH value of the mixed solution reached 9, and it was kept overnight at 60 °C. Then the aged Cu catalyst was taken out and calcined at 450 °C for 6 h to obtain CuO / silica-alumina gel.

[0102] 3) Hydrophobic modification of the catalyst:

[0103] The CuO / silica-alumina gel was impregnated in an aqueous ethanol solution of ethyltrimethoxysilane (mass percentage concentration: 7%), and the mass of ethyltrimethoxysilane accounted for 9% of the mass of CuO / silica-alumina gel. It was refluxed at 70 °C for 6 h, and then the liquid was evaporated to dryness to obtain a hydrophobically modified CuO / silica-alumina gel catalyst, in which the mass content of Cu measured by ICP was 27%.

[0104] 4) Catalyst evaluation, synthesis reaction:

[0105] The hydrophobically modified CuO / silica-alumina gel catalyst was granulated into 20 - 40 mesh, and 4 g of the catalyst was put into a catalyst evaluation device. First, it was reduced at 500 °C for 6 h (online reduction of the catalyst), and then the temperature was lowered to the reaction temperature for reaction. The raw material was isopropanol, and then it was fed according to the proportion of a raw material mass space velocity of 1.0 / h, a molar ratio of hydrogen:isopropanol = 3, and ammonia:isopropanol = 7. The reaction was tested at a reaction temperature of 165 °C and a reaction pressure of 2 MPa. The test results were an isopropanol conversion rate of 99.1%, a selectivity of 98.3% for monoisopropylamine, and a selectivity of 1.5% for diisopropylamine. Comparative Example 1

[0106] Basically the same as Example 1, the difference was only that: step 3) was not carried out, that is, no hydrophobic modification treatment was performed. The Co / silica-alumina gel catalyst obtained in step 2) was directly used in step 4). The test result was an isopropanol conversion rate of 50.6%. Comparative Example 2

[0107] Basically the same as Example 1, the difference was only that: step 1) was not carried out, that is, no carrier acid modification treatment was performed. The silica-alumina gel powder was directly used for the impregnation in step 2). The test result was an isopropanol conversion rate of 85.1%.

[0108] It can be seen that in the present invention, the carrier is first subjected to acid treatment and / or alkali treatment. During acid treatment, a part of Al in the carrier is removed by reaction, the Si-O-Al bond in the carrier is broken between O and Al, and a pore structure is formed in the corresponding part of Al. In this structure, an Si-OH structure is generated. During alkali treatment, a part of Si in the carrier is removed by reaction, the Si-O-Al bond in the carrier is broken between O and Si, and a pore structure is formed in the corresponding part. In this structure, an Al-OH structure is generated. Then, the carrier is loaded with an oxide of an active metal component, and finally, it is subjected to hydrophobic modification. The silane coupling agent for hydrophobic modification will hydrolyze to generate an Si-OH structure. The Si-OH or Al-OH in the pore structure of the carrier will undergo a condensation reaction with the Si-OH generated by the hydrolysis of the hydrophobic modifier, so that the group around the pore structure is modified into a hydrophobic group, and the active component is basically loaded in the pore structure. Therefore, after hydrophobic modification, the environment around the active component in the catalyst is a hydrophobic environment, providing an anhydrous-like environment on the surface of the active component of the catalyst. This environment repels water, promotes the departure of the water generated during the preparation of isopropylamine from isopropanol, and makes the equilibrium reaction shift forward, thereby significantly improving the conversion rate of isopropanol. When the carrier is not subjected to acid treatment or alkali treatment, or even if it is treated, but the silane hydrophobic treatment is not carried out after loading the active component, the aforementioned anhydrous environment cannot be formed, which is not conducive to the improvement of the isopropanol conversion rate.

[0109] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0110] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

Claims

1. A method for preparing isopropylamine from isopropanol, using isopropanol and ammonia as raw materials, reacting in the presence of a catalyst to produce the isopropylamine, characterized in that: The catalyst is prepared by a preparation method including the following steps: 1) subjecting the support to acid treatment and / or base treatment to obtain a treated support, wherein the support contains silicon and / or aluminum elements; 2) loading an oxide of an active metal component on the treated support to obtain a catalyst precursor. 3) The catalyst precursor is hydrophobically modified with a silane coupling agent, and the catalyst is obtained after reduction; the acid used in the acid treatment is selected from one or a combination of citric acid, oxalic acid, and acetic acid; the base used in the base treatment is selected from one or two of sodium hydroxide and potassium hydroxide; the acid treatment is achieved by immersing the carrier in an aqueous solution of the acid; the base treatment is achieved by immersing the carrier in an aqueous solution of the base; the silane coupling agent is (R1) n Si(OR2) m , where R1 is independently selected from methyl, ethyl, or propyl, R2 is independently selected from methyl or ethyl, n is 1, 2, or 3, m is 1, 2, or 3, and n + m = 4; the hydrophobic modification is achieved by immersing the catalyst precursor in a solution of the silane coupling agent.

2. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The support is selected from one or a combination of silica-alumina gel, silica, ZSM-5 molecular sieve, and Beta molecular sieve.

3. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The temperature of the acid treatment and / or base treatment is 50-60°C.

4. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: When the support is silica-alumina gel or ZSM-5 molecular sieve, the support is subjected to acid treatment and / or base treatment in step 1); or when the support is silica, the support is subjected to base treatment in step 1); or when the support is Beta molecular sieve, the support is subjected to acid treatment in step 1).

5. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The time of the acid treatment and / or base treatment is 2-6 h.

6. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: In step 2), the active component is loaded on the treated support by an impregnation method or a co-precipitation method; and / or, by mass percentage, the catalyst comprises 10%-27% of an active metal component and 73%-90% of the treated support.

7. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The active metal component is selected from Ni, Co, Cu, Cu / Pt, Cu / Ni, or Ni / Pt, wherein Cu / Pt is a combination of Cu and Pt, Cu / Ni is a combination of Cu and Ni, and Ni / Pt is a combination of Ni and Pt.

8. The method for preparing isopropylamine from isopropanol according to claim 7, characterized in that: In the Cu / Pt or Ni / Pt, the mass percentage of Pt in the catalyst is 0.5%-5%; in the Cu / Ni, the mass percentage of Cu in the catalyst is 10%-15%.

9. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The temperature of the hydrophobic modification is 60-80°C.

10. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The time of the hydrophobic modification is 4-12 h.

11. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The mass of the silane coupling agent accounts for 5%-10% of the mass of the catalyst precursor.

12. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: The mass hourly space velocity of the isopropanol is 0.5 - 3 h -1 ; and / or, the temperature of the reaction is 165 - 195 °C; and / or, the pressure of the reaction is 1 - 2 MPa; and / or, the molar ratio of the isopropanol to ammonia is 1:1 - 7; and / or, the reaction is carried out in a hydrogen atmosphere, and the molar ratio of the isopropanol to hydrogen is 1:1 - 3.

13. The method for preparing isopropylamine from isopropanol according to claim 1, characterized in that: Isopropylamine is used to replace ammonia, and the molar ratio of isopropanol to isopropylamine is 1:1.1-1:1.5.