A method for the direct preparation of diisopropylamine from monoisopropylamine

Abstract

This invention discloses a method for directly preparing diisopropylamine from monoisopropylamine. The catalytic material used in this method is a coated metal@molecular sieve catalyst. The coated metal@molecular sieve catalyst of this invention refers to a catalyst in which an active metal is fixed inside the crystal structure of a molecular sieve catalyst. The coated metal@molecular sieve catalyst used in this invention can be prepared by loading the active metal onto the raw material for synthesizing the molecular sieve, and then synthesizing the active metal to coat the crystal structure of the molecular sieve. The metal@molecular sieve catalyst prepared by this invention, due to the abundant pore structure of the support material, can improve the conversion rate of isopropylamine; because the active component is stably fixed inside the molecular sieve crystal structure, sintering will not occur during catalyst preparation and reaction, ensuring the stability of the catalyst.

Description

Technical Field

[0001] This invention relates to a method for directly preparing diisopropylamine from monoisopropylamine. Background Technology

[0002] Diisopropylamine, as a raw material for organic synthesis, is mainly used in the production of pharmaceuticals, pesticides, dyes, rubber vulcanization accelerators, emulsifiers, and detergents. Specific applications include the synthesis of pharmaceutical products such as Hepatoprotective Agent and Viproamine, as well as pesticide herbicides such as Oat Killer No. 1 and No. 2.

[0003] Diisopropylamine is usually prepared by isopropanol amination. However, isopropanol produces water during amination, and the raw material isopropanol, product water, and diisopropylamine form a ternary azeotropic system, which makes it difficult to separate the target product. This synthesis process has high energy consumption and low separation efficiency, and is not suitable for industrial production.

[0004] In addition, diisopropylamine can also be synthesized via the alkyl transfer reaction of isopropylamine, which requires a catalyst. Patent CN103787892A discloses the use of a K-Beta-Al2O3 catalyst to catalyze this reaction, but the conversion rate of isopropylamine is only 15.89%-34.67%, which is still very low. Patent CN1127373C discloses the use of a ZrO2 / Beta-Al2O3 catalyst to catalyze this reaction. Although the conversion rate of isopropylamine can reach up to 72.46%, and the total selectivity of diisopropylamine and triisopropylamine is 98.14%, the selectivity of diisopropylamine is only 54%, meaning that the selectivity of diisopropylamine in this reaction is low. Patent CN102614894B discloses the use of NiCuPt / Al2O3 catalyst to catalyze this reaction, in which the conversion rate of isopropylamine is the highest at 63.3% and the selectivity of diisopropylamine is 99.5%. Although this catalyst can achieve high conversion and selectivity, it is prepared by impregnation method and the reaction temperature during catalyst preparation is higher than 200℃. At this high temperature, the catalyst is prone to sintering, which will lead to the stability of the catalyst, that is, the catalytic activity will decrease after long-term operation, i.e., the catalyst life is not long enough.

[0005] Existing catalysts cannot simultaneously achieve high isopropylamine conversion and high diisopropylamine reaction selectivity in the alkyl transfer reaction of isopropylamine to synthesize diisopropylamine, as well as high catalyst stability that can maintain catalytic activity for a long period of time. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an improved method for the direct preparation of diisopropylamine from monoisopropylamine, which addresses the shortcomings and deficiencies of the prior art. This method can simultaneously achieve high isopropylamine conversion rate and high diisopropylamine reaction selectivity, and the catalyst activity does not decrease during long-term operation of the reaction.

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

[0008] In some embodiments, a method for preparing diisopropylamine involves using isopropylamine as a raw material and conducting an alkyl transfer reaction in the presence of a catalyst to generate the diisopropylamine. The catalyst comprises a molecular sieve support and an active metal component fixed within the crystal structure of the molecular sieve support.

[0009] In some embodiments, the molecular sieve support is selected from ZSM-5 or Beta molecular sieve.

[0010] In some embodiments, the catalyst comprises, by weight percentage, 10%-25% of an active metal component and 75%-90% of a molecular sieve support.

[0011] In some embodiments, the active metal component is selected from one or more combinations of Ni, Co, Cu, Pt, Sn, Ru, and Re.

[0012] In some embodiments, when the active metal component contains Ni, Co, or Cu, the Ni, Co, or Cu accounts for 10%-21% of the mass percentage of the catalyst.

[0013] In some embodiments, when the active metal component contains Pt, Sn, Ru, or Re, the mass percentage of Pt, Sn, Ru, or Re in the catalyst is 0.5%-5%.

[0014] In some embodiments, the catalyst is prepared by a method comprising the following steps: 1) loading an active metal oxide onto a support by impregnation or hydrolysis to obtain an active metal oxide / support; 2) subjecting a silicon source, an aluminum source, an organic template agent, and the active metal oxide / support to a hydrothermal reaction, followed by filtration and calcination to obtain a catalyst precursor; 3) reducing the catalyst precursor with a reducing agent to obtain the catalyst; the support is selected from silica or aluminosilicate. The above-mentioned support is one of the raw materials for synthesizing molecular sieve supports.

[0015] In some embodiments, the catalyst is prepared by a method comprising the following steps: 1) loading an active metal oxide onto a molecular sieve support by impregnation to obtain an active metal oxide / molecular sieve support; 2) subjecting an organic template agent, the active metal oxide / molecular sieve support, and an optional silicon source to a hydrothermal reaction, followed by filtration and calcination to obtain a catalyst precursor; 3) reducing the catalyst precursor with a reducing agent to obtain the catalyst; the molecular sieve support and the molecular sieve carrier may be of the same or different types. The aforementioned molecular sieve support is also a molecular sieve, but in subsequent molecular sieve carrier synthesis reactions, the molecular sieve carrier is generated in situ or formed through crystal transformation. The molecular sieve support can be the same type of molecular sieve crystal as the molecular sieve carrier of the catalyst (in this case, equivalent to a seed crystal), or it can be a different type of molecular sieve crystal from the molecular sieve carrier of the catalyst; when the molecular sieve support and the molecular sieve carrier of the catalyst are of different types, they are grown by crystal transformation.

[0016] In some embodiments, the silicon source is selected from one or more combinations of silica sol, silica gel, and sodium silicate.

[0017] In some embodiments, the aluminum source is selected from one or more combinations of aluminum hydroxide, boehmite, alumina, and aluminum isopropoxide.

[0018] In some embodiments, the organic template agent is selected from tetrapropylammonium hydroxide (abbreviated TPAOH, a template agent for ZSM-5 molecular sieve) or tetraethylammonium hydroxide (abbreviated TEAOH, a template agent for Beta molecular sieve).

[0019] In some embodiments, the impregnation method involves impregnating silica or aluminosilicate gel with a water-soluble salt solution of the active metal component. After impregnation, the resulting solid is calcined to obtain the active metal oxide / support. The impregnation method can be an equal-volume impregnation method.

[0020] In some embodiments, during the hydrolysis method, a water-soluble salt solution of the active metal component is reacted with a tetraalkoxysilane to remove water, resulting in a solid which is then calcined to obtain an active metal oxide / support. The tetraalkoxysilane hydrolyzes to form silicon oxide. The tetraalkoxysilane may be a tetraethoxysilane.

[0021] In some embodiments, the molar ratio of silicon in the silicon source and active metal oxide / support, aluminum in the aluminum source, and organic template agent is 1:0.005-0.02:0.02-0.4, preferably 1:0.01:0.2-0.4.

[0022] In some embodiments, the molecular sieve support is a ZSM-5 molecular sieve, the molecular sieve carrier is a ZSM-5 molecular sieve, the molecular sieve support and the molecular sieve carrier are of the same type, and in step 2), the raw materials for the hydrothermal reaction include a silicon source.

[0023] In some embodiments, the molar ratio of silicon to organic template agent in the silicon source is 0.4-0.6:0.2-0.4, preferably 0.5:0.3; the mass ratio of the active metal oxide / molecular sieve support to the silicon source is 1-2:1.

[0024] In some embodiments, the molecular sieve support is a Y molecular sieve, and the molecular sieve carrier is a ZSM-5 molecular sieve. The molecular sieve support and the molecular sieve carrier are of different types. In step 2), no silicon source is added during the hydrothermal reaction.

[0025] In some embodiments, the temperature of the hydrothermal reaction is 120-160°C.

[0026] In some embodiments, the calcination temperature is 400-600 °C.

[0027] In some embodiments, the reducing agent is hydrogen.

[0028] In some embodiments, the reduction reaction is carried out at a temperature of 400-600°C.

[0029] In some embodiments, the mass hourly space velocity (HHSV) of the isopropylamine is 0.5-3 h⁻¹. -1 .

[0030] In some embodiments, the temperature of the alkyl transfer reaction is 170-190°C.

[0031] In some embodiments, the pressure of the alkyl transfer reaction is 0.2-0.6 MPa.

[0032] In some embodiments, the alkyl transfer reaction is carried out under hydrogen-containing conditions.

[0033] In some embodiments, the alkyl transfer reaction is carried out in a hydrogen atmosphere, and the molar ratio of isopropylamine to hydrogen is 1:1-5.

[0034] The present invention also provides the aforementioned catalyst.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] The catalyst used in the synthesis method of this invention is a coated metal@molecular sieve catalyst. This catalyst possesses the structural effect of a molecular sieve, and the active component can be immobilized within the crystal structure of the molecular sieve. This allows for the simultaneous achievement of high isopropylamine conversion and high diisopropylamine reaction selectivity when catalyzing the direct preparation of diisopropylamine from isopropylamine. Furthermore, the active component exhibits excellent anti-sintering properties, improving catalyst stability and ensuring long-term operation without decrease in catalytic activity. In this invention, the active metal component is stably coated within the crystal framework structure of the molecular sieve catalyst support (e.g., by first impregnating the active component with the raw material for synthesizing the molecular sieve, or by obtaining the molecular sieve raw material with the immobilized active component through hydrolysis, and then using it as one of the raw materials to synthesize the molecular sieve). During the reaction, the catalyst does not exhibit metal migration or agglomeration, thus improving catalyst stability. The preparation method of the coated molecular sieve catalyst involves first immobilizing the active component on a support, and then using the immobilized support as a raw material to synthesize the metal@molecular sieve catalyst.

[0037] The synthesis method of the present invention can achieve a conversion rate of monoisopropylamine of up to 81.2% or more, a selectivity of diisopropylamine of up to 99.0% or more, and the catalytic activity of the catalyst remains basically unchanged after running for more than 950 hours. Attached Figure Description

[0038] Figure 1 The XRD pattern of the Ni@ZSM-5 catalyst prepared in Example 2 is shown below.

[0039] Figure 2 The image shows the XRD pattern of the Cu@Beta catalyst prepared in Example 3. Detailed Implementation

[0040] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0041] In this invention, "metal component / carrier" refers to a carrier that directly loads a metal component through methods such as impregnation. The metal component is usually located on the surface of the carrier. For example, Co3O4-NiO / ZSM-5 means that Co3O4-NiO is located on the surface of ZSM-5. "Metal component@carrier" refers to a carrier that fixes and coats a metal component. The metal component is usually located inside the crystal structure of the carrier. For example, CoNi@ZSM-5 means that CoNi is located inside the crystal structure of ZSM-5.

[0042] The coated metal@molecular sieve catalyst of the present invention fixes the active metal inside the crystal structure of the molecular sieve material, stabilizes the active component, prevents the catalyst from sintering at high temperature during the reaction, and improves the stability of the catalyst.

[0043] Example 1

[0044] This embodiment provides a catalyst and uses it to catalyze the preparation of diisopropylamine from monoisopropylamine, as detailed below:

[0045] 1) Preparation of Co3O4 / SiO2:

[0046] Equal-volume impregnation was performed by impregnating silica in an aqueous solution containing cobalt nitrate. After impregnation, the powder was dried and then calcined to prepare Co3O4 / SiO2. Equal-volume impregnation means that the aqueous solution just barely covers the silica after it is added.

[0047] 2) Preparation of the molecular sieve catalyst Co@ZSM-5:

[0048] Sodium aluminate (NaAlO2), Co3O4 / SiO2, silica, and tetrapropylammonium hydroxide (TPAOH) (a 35% aqueous solution by mass) were added to water and stirred until homogeneous. The molar ratio of SiO2 (total SiO2 in Co3O4 / SiO2 and silica):NaAlO2:TPAOH:water was 1:0.01:0.2:30, and the mass ratio of Co3O4 / SiO2 to silica was 1:1. After homogeneous stirring, the mixture was placed in a polytetrafluoroethylene-lined reactor and crystallized at 160℃ for 48 hours in a sealed reactor. After the reaction, the solid was washed with deionized water until the pH of the filtered water reached 7. The filtered solid was then calcined at 550℃ for 4 hours to obtain Co3O4@ZSM-5. Finally, Co3O4@ZSM-5 was reduced at 500℃ for 6 hours under a hydrogen atmosphere to obtain the reduced catalyst Co@ZSM-5. ICP analysis showed that the mass percentage of Co in the catalyst was 16%.

[0049] 3) Catalyst evaluation and synthesis reaction:

[0050] The prepared catalyst Co@ZSM-5 was granulated to 20-40 mesh, and 4g of the catalyst was placed in a catalyst evaluation device. The feedstock was monoisopropylamine, and the catalyst was fed at a mass hourly space velocity (MHSV) of 1 / h and a hydrogen-to-monoisopropylamine molar ratio of 3. The reaction temperature was 170℃, and the reaction pressure was 0.4MPa. The test results showed a monoisopropylamine conversion of 81.2% and a diisopropylamine selectivity of 99.1%. After 1000h of operation, the catalyst performance was: monoisopropylamine conversion of 80.1% and diisopropylamine selectivity of 99.3%.

[0051] Example 2

[0052] This embodiment provides a catalyst and uses it to catalyze the preparation of diisopropylamine from monoisopropylamine, as detailed below:

[0053] 1) Preparation of NiO / SiO2:

[0054] By hydrolysis, tetraethoxysilane is added to an aqueous solution of nickel nitrate. After stirring thoroughly, the water is continuously evaporated to dryness. The solid obtained after evaporation is then calcined to obtain NiO / SiO2.

[0055] 2) Preparation of Ni@ZSM-5 molecular sieve catalyst:

[0056] Boehmite (AlOOH hydrate), NiO / SiO2, fine silica gel, and tetrapropylammonium hydroxide (TPAOH) (35% aqueous solution by mass percentage) were added to water and stirred until homogeneous. The molar ratio of SiO2 (total SiO2 in NiO / SiO2 and fine silica gel):AlOOH:TPAOH:water was 1:0.01:0.2:30, and the mass ratio of NiO / SiO2 to fine silica gel was 1:1. After homogeneous stirring, the mixture was placed in a polytetrafluoroethylene-lined reactor and crystallized at 160℃ for 48 hours in a sealed reactor. After the reaction, the solid was washed with deionized water until the pH of the filtered water reached 7. The filtered solid was then calcined at 550℃ for 4 hours to obtain NiO@ZSM-5. Finally, NiO@ZSM-5 was reduced at 500℃ for 6 hours under a hydrogen atmosphere to obtain the reduced catalyst Ni@ZSM-5. The mass percentage content of Ni in the catalyst was determined by ICP to be 21%.

[0057] 3) Catalyst evaluation and synthesis reaction:

[0058] The prepared catalyst was granulated to 20-40 mesh, and 4g of catalyst was placed in a catalyst evaluation device. The feedstock was monoisopropylamine, fed at a mass hourly space velocity (MHSV) of 1 / h and a hydrogen-to-monoisopropylamine molar ratio of 3. The reaction temperature was 180℃, and the reaction pressure was 0.5MPa. The test results showed a monoisopropylamine conversion of 82.2% and a diisopropylamine selectivity of 99.1%. After 950 hours of operation, the catalyst performance was: monoisopropylamine conversion of 81.1% and diisopropylamine selectivity of 99.2%.

[0059] Example 3

[0060] This embodiment provides a catalyst and uses it to catalyze the preparation of diisopropylamine from monoisopropylamine, as detailed below:

[0061] 1) Preparation of Cu / aluminosilicate adhesive:

[0062] Aluminosilicate silica gel (with an atomic molar ratio of 100 for silicon and aluminum) was impregnated in an aqueous solution containing copper nitrate using an equal-volume impregnation method. After impregnation, the powder was dried and then calcined to prepare CuO / aluminosilicate silica gel.

[0063] 2) Preparation of Cu@Beta catalyst:

[0064] CuO / aluminosilicate gel, fine silica gel, and tetraethylammonium hydroxide (TEAOH) (35% aqueous solution by mass) were added to water and stirred until homogeneous. The molar ratio of Si:Al:TEAOH:water was 1:0.01:0.4:40, and the mass ratio of Cu / aluminosilicate gel to fine silica gel was 1:1. After homogeneous stirring, the mixture was placed in a polytetrafluoroethylene-lined reactor and crystallized at 120°C for 72 hours in a sealed reactor. After the reaction, the solid was washed with deionized water until the pH of the filtered water reached 7, yielding CuO@Beta. The filtered solid was calcined at 550°C for 4 hours to obtain CuO@Beta. Finally, CuO@Beta was reduced at 500°C for 6 hours under a hydrogen atmosphere to obtain the reduced catalyst Cu@Beta. ICP analysis showed that the mass percentage content of Cu in the catalyst was 19%.

[0065] 3) Catalyst evaluation and synthesis reaction:

[0066] The prepared catalyst was granulated to 20-40 mesh, and 4g of catalyst was placed in a catalyst evaluation device. The feedstock was monoisopropylamine, and the catalyst was fed at a mass hourly space velocity (MHSV) of 1 / h and a molar ratio of hydrogen to monoisopropylamine of 5. The reaction temperature was 170℃, and the reaction pressure was 0.6MPa. The test results showed a monoisopropylamine conversion of 84.1% and a diisopropylamine selectivity of 99.6%. After 1000 hours of operation, the catalyst performance was as follows: monoisopropylamine conversion of 82.9% and diisopropylamine selectivity of 99.4%.

[0067] Example 4

[0068] This embodiment provides a catalyst and uses it to catalyze the preparation of diisopropylamine from monoisopropylamine, as detailed below:

[0069] 1) Preparation of Co3O4-NiO / ZSM-5:

[0070] ZSM-5 molecular sieve (with a silicon-to-aluminum atomic molar ratio of 100) was impregnated in an aqueous solution containing cobalt nitrate and nickel nitrate using an equal-volume impregnation method. After impregnation, the powder was dried and then calcined to prepare Co3O4-NiO / ZSM-5. At this point, Co3O4-NiO is located on the surface of ZSM-5.

[0071] 2) Preparation of CoNi@ZSM-5 catalyst:

[0072] Silica and tetrapropylammonium hydroxide (TPAOH) (35% aqueous solution by mass) were added to water and stirred until homogeneous. The molar ratio of SiO2:TPAOH:water was 0.5:0.3:30. After thorough stirring, Co3O4-NiO / ZSM-5 was added, at 100% of the mass of silica. The mixture was then placed in a polytetrafluoroethylene-lined reactor and sealed for crystallization at 160℃ for 12 hours. After the reaction, the solid was washed with deionized water until the pH of the filtered water reached 7, yielding Co3O4-NiO@ZSM-5. The filtered solid was calcined at 550℃ for 4 hours to obtain Co3O4-NiO@ZSM-5. Finally, Co3O4@ZSM-5 was reduced at 500℃ for 6 hours under a hydrogen atmosphere to obtain the reduced catalyst CoNi@ZSM-5. ICP analysis showed that the mass percentage content of Co in the catalyst was 11%, and the mass percentage content of Ni was 12%. At this time, CoNi is located inside the ZSM-5 crystal structure.

[0073] 3) Catalyst evaluation and synthesis reaction:

[0074] The prepared catalyst was granulated to 20-40 mesh, and 4g of catalyst was placed in a catalyst evaluation device. The feedstock was monoisopropylamine, and the catalyst was fed at a mass hourly space velocity (MHSV) of 1 / h and a molar ratio of hydrogen to monoisopropylamine of 5. The reaction temperature was 185℃, and the reaction pressure was 0.6MPa. The test results showed a monoisopropylamine conversion of 83.2% and a diisopropylamine selectivity of 99.2%. After 1100 hours of operation, the catalyst performance was as follows: monoisopropylamine conversion of 81.9% and diisopropylamine selectivity of 99.4%.

[0075] Example 5

[0076] This embodiment provides a catalyst and uses it to catalyze the preparation of diisopropylamine from monoisopropylamine, as detailed below:

[0077] 1) Preparation of NiO-PtO2 / Y:

[0078] NiO-PtO2 / Y was prepared by impregnating a Y molecular sieve (with an atomic molar ratio of silicon to aluminum of 100) in an aqueous solution containing nickel nitrate and chloroplatinic acid using an equal-volume impregnation method. After impregnation, the powder was dried and then calcined.

[0079] 2) Preparation of NiPt@ZSM-5 catalyst:

[0080] NiO-PtO2 / Y and tetrapropylammonium hydroxide (35% aqueous solution by mass) were added to water and stirred until homogeneous, with the molar ratio of Si:Al:TPAOH:water being 1:0.01:0.2:30. After homogeneous stirring, the mixture was placed in a polytetrafluoroethylene-lined reactor and the reactor was sealed and crystallized at 160℃ for 24 hours (this process is called crystallization, where Y molecular sieve is converted to ZSM-5). After the reaction, the solid was washed with deionized water until the pH of the filtered water reached 7, yielding NiO-PtO2@ZSM-5. The filtered solid was then calcined at 550℃ for 4 hours to obtain H... + -NiO-PtO2@ZSM-5. Finally, H + NiO-PtO2@ZSM-5 was reduced at 500℃ for 6 h in a hydrogen atmosphere to obtain the reduced catalyst NiPt@ZSM-5. ICP analysis showed that the mass percentage content of Ni in the catalyst was 15%, and the mass percentage content of Pt in the catalyst was 1%.

[0081] 3) Catalyst evaluation and synthesis reaction:

[0082] The prepared catalyst was granulated to 20-40 mesh, and 4g of catalyst was placed in a catalyst evaluation device. The feedstock was monoisopropylamine, and the catalyst was fed at a mass hourly space velocity (MHSV) of 1 / h and a molar ratio of hydrogen to monoisopropylamine of 7. The reaction temperature was 165℃, and the reaction pressure was 0.2MPa. The test results showed a monoisopropylamine conversion of 81.9% and a diisopropylamine selectivity of 99.0%. After 950 hours of operation, the catalyst performance was as follows: monoisopropylamine conversion of 80.9% and diisopropylamine selectivity of 99.3%.

[0083] Comparative Example 1

[0084] The NiCuPt / Al2O3 catalyst disclosed in patent CN102614894B is specifically the catalyst in experimental example 1 of that patent.

[0085] Catalyst evaluation:

[0086] Same as Example 1. The test results showed that the conversion rate of monoisopropylamine was 62.1%, and the selectivity of diisopropylamine was 99.5%. After running for 500 hours, the conversion rate of monoisopropylamine was 30.8%, and the selectivity of diisopropylamine was 99.6%.

[0087] Comparative Example 2

[0088] This comparative example provides a catalyst (without pre-fixing the active component) and uses it to catalyze the preparation of diisopropylamine from monoisopropylamine, as detailed below:

[0089] 1) Preparation of Co3O4-NiO / ZSM-5:

[0090] ZSM-5 molecular sieve (with an atomic molar ratio of silicon to aluminum of 100) was impregnated in an aqueous solution containing cobalt nitrate and nickel nitrate by an equal-volume impregnation method. The mass contents of Co and Ni were 15% of the mass of ZSM-5 molecular sieve, respectively. After impregnation, the powder was dried and then calcined to prepare Co3O4-NiO / ZSM-5.

[0091] 2) Preparation of CoNi / ZSM-5 catalyst:

[0092] Co3O4-NiO / ZSM-5 was reduced at 500℃ for 6 h in a hydrogen atmosphere to obtain the reduced CoNi / ZSM-5 catalyst. ICP analysis showed that the mass percentage of Co in the catalyst was 11%, and the mass percentage of Ni was 12%. At this point, CoNi remained on the catalyst surface.

[0093] 3) Catalyst evaluation and synthesis reaction:

[0094] Same as Example 4. Test results: Monoisopropylamine conversion rate 81.2%, diisopropylamine selectivity 99.0%. After 600 hours of operation, the monoisopropylamine conversion rate was 40.9%, and the diisopropylamine selectivity was 99.2%.

[0095] Comparative Example 3

[0096] This comparative example provides a catalyst (without pre-fixing the active component) and uses it to catalyze the preparation of diisopropylamine from monoisopropylamine, as detailed below:

[0097] 1) Preparation of CuO / Beta:

[0098] Beta molecular sieves (with an atomic molar ratio of silicon to aluminum of 100) were impregnated in an aqueous solution containing copper nitrate using an equal-volume impregnation method. The mass content of Cu was 15% of the mass of the Beta molecular sieves. After impregnation, the solid was dried and calcined at 550°C for 4 hours to obtain CuO@Beta.

[0099] 2) Preparation of Cu / Beta catalyst:

[0100] CuO / Beta was reduced at 500℃ for 6 h in a hydrogen atmosphere to obtain the reduced catalyst Cu@Beta. ICP analysis showed that the mass percentage of Cu in the catalyst was 19%.

[0101] 3) Catalyst evaluation and synthesis reaction:

[0102] Same as Example 3. Test results: Monoisopropylamine conversion rate 81.3%, diisopropylamine selectivity 99.3%. After 600 hours of operation, the monoisopropylamine conversion rate was 35.6%, and the diisopropylamine selectivity was 99.2%.

[0103] It is evident that if the active components are not fixed before the molecular sieve is synthesized in situ during catalyst preparation, the active components are prone to sintering, significantly reducing the stability of the catalyst and decreasing its catalytic activity after long-term operation.

Claims

1. A method for preparing diisopropylamine, comprising using isopropylamine as a raw material and subjecting it to an alkyl transfer reaction in the presence of a catalyst to generate the diisopropylamine, characterized in that: The catalyst comprises a molecular sieve support and an active metal component immobilized within the crystal structure of the molecular sieve support; the molecular sieve support is selected from ZSM-5 or Beta molecular sieve; the active metal component is selected from one or more combinations of Ni, Co, Cu, and Pt. The catalyst is prepared by a method including the following steps: 1) loading an active metal oxide onto a support by impregnation or hydrolysis to obtain an active metal oxide / support; 2) subjecting a silicon source, an aluminum source, an organic template agent, and the active metal oxide / support to a hydrothermal reaction, followed by filtration and calcination to obtain a catalyst precursor. 3) The catalyst precursor is reduced using a reducing agent to obtain the catalyst; The support is selected from silicon oxide or aluminum silicate; Alternatively, the catalyst may be prepared by a method comprising the following steps: 1) loading an active metal oxide onto a molecular sieve support by an impregnation method to obtain an active metal oxide / molecular sieve support; 2) The organic template agent, the active metal oxide / molecular sieve support, and an optional silicon source are subjected to a hydrothermal reaction, filtered, and calcined to obtain a catalyst precursor; 3) The catalyst precursor is reduced with a reducing agent to obtain the catalyst; the molecular sieve support and the molecular sieve carrier may be of the same or different types; The organic template agent is selected from tetrapropylammonium hydroxide or tetraethylammonium hydroxide.

2. The method for preparing diisopropylamine according to claim 1, characterized in that: The catalyst comprises 10%-25% active metal components and 75%-90% molecular sieve support by mass percentage.

3. The method for preparing diisopropylamine according to claim 1, characterized in that: When the active metal component contains Ni, Co, or Cu, the mass percentage of Ni, Co, or Cu in the catalyst is 10%-21%; when the active metal component contains Pt, the mass percentage of Pt in the catalyst is 0.5%-5%.

4. The method for preparing diisopropylamine according to claim 1, characterized in that: The silicon source is selected from one or more combinations of silica sol, silica gel, and sodium silicate.

5. The method for preparing diisopropylamine according to claim 1, characterized in that: The aluminum source is selected from one or more combinations of aluminum hydroxide, boehmite, alumina, and aluminum isopropoxide.

6. The method for preparing diisopropylamine according to claim 1, characterized in that: In the impregnation method, a water-soluble salt solution of the active metal component is impregnated with silicon oxide or aluminosilicate gel. After impregnation, the solid obtained after impregnation is calcined to obtain an active metal oxide / support.

7. The method for preparing diisopropylamine according to claim 1, characterized in that: In the hydrolysis method, a water-soluble salt solution of the active metal component is reacted with tetraalkoxysilane to remove water, and the resulting solid is calcined to obtain an active metal oxide / support.

8. The method for preparing diisopropylamine according to claim 1, characterized in that: The molar ratio of silicon in the silicon source and active metal oxide / support, aluminum in the aluminum source, and organic template agent is 1:0.005-0.02:0.02-0.

4.

9. The method for preparing diisopropylamine according to claim 1, characterized in that: The molecular sieve support is ZSM-5 molecular sieve, the molecular sieve carrier is ZSM-5 molecular sieve, the molecular sieve support and the molecular sieve carrier are of the same type, and in step 2), the raw materials for the hydrothermal reaction include a silicon source.

10. The method for preparing diisopropylamine according to claim 9, characterized in that: The molar ratio of silicon to organic template agent in the silicon source is 0.4-0.6:0.2-0.4; the mass ratio of the active metal oxide / molecular sieve support to the silicon source is 1-2:

1.

11. The method for preparing diisopropylamine according to claim 1, characterized in that: The molecular sieve support is a Y molecular sieve, and the molecular sieve carrier is a ZSM-5 molecular sieve. The molecular sieve support and the molecular sieve carrier are of different types. In step 2), no silicon source is added during the hydrothermal reaction.

12. The method for preparing diisopropylamine according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 120-160℃.

13. The method for preparing diisopropylamine according to claim 1, characterized in that: The calcination temperature is 400-600℃.

14. The method for preparing diisopropylamine according to claim 1, characterized in that: The reducing agent is hydrogen; and / or the temperature of the reduction reaction is 400-600℃.

15. The method for preparing diisopropylamine according to claim 1, characterized in that: The mass hourly space velocity (MSV) of the isopropylamine is 0.5-3 h⁻¹. -1 .

16. The method for preparing diisopropylamine according to claim 1, characterized in that: The temperature of the alkyl transfer reaction is 170-190°C; and / or the pressure of the alkyl transfer reaction is 0.2-0.6 MPa.

17. The method for preparing diisopropylamine according to claim 1, characterized in that: The alkyl transfer reaction is carried out under hydrogen-containing conditions.

18. The method for preparing diisopropylamine according to claim 1, characterized in that: The alkyl transfer reaction is carried out in a hydrogen atmosphere, and the molar ratio of isopropylamine to hydrogen is 1:1-5.

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