Method for producing monomethylamine and dimethylamine

Abstract

The invention relates to the technical field of methylamine production, and discloses a method for producing monomethylamine and dimethylamine. The method comprises the following steps: methanol and ammonia are subjected to a contact reaction with a catalyst; the catalyst comprises a carrier and an active component loaded on the carrier; the carrier contains a silicon-phosphorus-aluminum molecular sieve with a CHA structure, and the active component is magnesium / or zinc; wherein on the basis of the total mass of the catalyst, the mass content of the active component in terms of oxide is 0.1-10%. By adopting the method provided by the invention, the purpose of high-selectivity yield increase of monomethylamine and dimethylamine can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of methylamine production, and particularly relates to a method for producing monomethylamine and dimethylamine. BACKGROUND

[0002] Methylamine is an important organic chemical raw material product, and its product categories mainly include monomethylamine, dimethylamine and trimethylamine. Methylamine has wide industrial uses, for example, monomethylamine can be used for pesticides, medicines, surfactants, dyes, accelerators, ion exchange resins, dyes, developers, solvents and the like, dimethylamine can be used for producing high-quality chemical fiber solvents and polyurethane solvents, and trimethylamine is mainly used for feed additives and reagent disinfectants. The three kinds of methylamines have different uses. However, when using a traditional catalyst to produce methylamine, the proportion of trimethylamine in the obtained methylamine product is relatively high.

[0003] At present, all the catalysts used in industrial devices are equilibrium catalysts, that is, the mixed methylamine product synthesized by methanol and liquid ammonia is a thermodynamic equilibrium product distribution, and the equilibrium group of monomethylamine and dimethylamine accounts for about 45-50wt% of the mixed methylamine. Molecular sieves are reported as main components for synthesizing methylamine catalysts, and typical examples include ZSM-5 (US4082805), offretite (USP4254061), Y type, A type (USP4436938), ZK-5 (USP879444, Journal of Catalysis 1988113:367) and the like. The catalyst developed by Mitsubishi Rayon Corporation with a 2-5nm particle size and a crystallinity greater than or equal to 60% can increase the selectivity of dimethylamine. There are also many modifications of molecular sieves, such as CN102513147A, which can change the proportion of the three mixed amines by means of alkali metal modification, rare earth modification, phosphorus element modification, water vapor treatment, alkali treatment and the like; DuPont Company and SINOPEC (Shanghai) Petroleum Chemical Research Institute Co., Ltd. respectively use modified molecular sieves as catalysts to improve the selectivity of dimethylamine. From the product distribution, the distribution of dimethylamine is mainly increased, and the amount of monomethylamine and trimethylamine is reduced.

[0004] Therefore, it is urgent to develop a catalyst capable of producing monomethylamine and dimethylamine with high selectivity to meet the different needs of enterprises. SUMMARY

[0005] The purpose of the present application is to overcome the problem that the yield of monomethylamine and dimethylamine needs to be further improved in the prior art, and to provide a method for producing monomethylamine and dimethylamine. The method provided by the present application can achieve the purpose of increasing the production of monomethylamine and dimethylamine with high selectivity.

[0006] In order to achieve the above object, the present application provides a method for producing monomethylamine and dimethylamine, which comprises: reacting methanol and ammonia with a catalyst; the catalyst comprises a carrier and an active component supported on the carrier; the carrier comprises a CHA structure-containing silico-phospho-aluminate molecular sieve, and the active component is magnesium and / or zinc.

[0007] Preferably, the content of the active component in terms of mass based on the total mass of the catalyst is 0.1-10% in terms of oxide.

[0008] Preferably, the grain size of the silico-phospho-aluminate molecular sieve is not more than 1 μm, preferably 450-650 nm.

[0009] Preferably, the content of silicon in terms of mass based on the total mass of the silico-phospho-aluminate molecular sieve is 10-25%, preferably 15-22% in terms of oxide.

[0010] The inventors of the present application have found that the silico-phospho-aluminate molecular sieve with CHA topology has a small pore opening and can have high selectivity for monomethylamine and dimethylamine, but the activity of the catalyst is low if it is used alone. The inventors of the present application have further found that the activity of the catalyst can be improved and the selectivity for monomethylamine and dimethylamine can be significantly improved by using the silico-phospho-aluminate molecular sieve in combination with a specific active component and controlling the content of the active component to be 0.1-10%. Preferably, the small-grain silico-phospho-aluminate molecular sieve is used and the content of silicon in the silico-phospho-aluminate molecular sieve is increased, so that the catalyst has high activity and the purpose of increasing the production of monomethylamine and dimethylamine with high selectivity is achieved. According to experiments, the selectivity for monomethylamine and dimethylamine is more than 90% and the conversion rate of methanol is more than 90% by using the method provided by the present application, and good effects are achieved. DETAILED DESCRIPTION

[0011] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges are provided as example of the starting point and the ending point for a range. Any numerical value, however, can be expressed as a range by either adding or subtracting a value thereof. The value of a range provided herein is intended to be a precise value, and any value outside of that particular range is not intended to be part of the range. Any value provided herein is intended to be a precise value, and any value outside of that particular value is not intended to be part of the range. The disclosure of a single value of a desired property also pertains to ranges based on that single value, unless the context clearly indicates otherwise.

[0012] In the present application, "optionally" means containing or not containing, adding or not adding, using or not using.

[0013] The present application provides a method for producing monomethylamine and dimethylamine, which comprises: reacting methanol and ammonia with a catalyst; the catalyst comprises a carrier and an active component supported on the carrier; the carrier comprises a CHA structure-containing silico-phospho-aluminate molecular sieve, and the active component is magnesium and / or zinc.

[0014] The mass content of the active component, on the basis of the total mass of the catalyst, is 0.1-10% as calculated in terms of oxides.

[0015] In the present application, the mass content of the active component, on the basis of the total mass of the catalyst, is 0.1-10%, preferably 1-7%, more preferably 1-5%, specifically, for example, any value in the range constituted by any two of the point values 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%. With this preferred embodiment, the selectivity of monomethylamine and dimethylamine is more favorably improved.

[0016] To further improve the catalytic performance of the catalyst, preferably, the mass content of the silico-phosphorous-aluminum molecular sieve, on the basis of the total mass of the catalyst, is 55-85%, preferably 60-80%, more preferably 70-80%, specifically, for example, any value in the range constituted by any two of the point values 55%, 60%, 65%, 70%, 75%, 80%, 85%.

[0017] According to the present application, preferably, the grain size of the silico-phosphorous-aluminum molecular sieve is not more than 1 μm, preferably 400-700 nm.

[0018] The present inventors have found in the course of their research that the intracrystalline diffusion channel of a small-grain silico-phosphorous-aluminum molecular sieve is shorter, the external specific surface area is larger, and the exposed orifices are more numerous, which makes the reactant and product molecules more efficiently enter and exit the molecular sieve channel, favoring an increase in the contact probability of the reactants with the catalytically active sites and, in turn, an improvement in the reaction activity.

[0019] In the present application, when the grains are spherical, the grain size refers to the grain diameter; when the grains are spheroidal, the grain size refers to the diameter of the largest circumscribed circle thereof.

[0020] The grain size according to the present application is determined by scanning electron microscopy, specifically by randomly taking 5-10 molecular sieve grains and measuring the grain size distribution thereof.

[0021] For example, a grain size of 500-600 nm means that the grain size of the molecular sieve grains randomly taken is distributed in the range of 500-600 nm.

[0022] According to the present application, preferably, the mass content of silicon is 10-30%, preferably 15-22%, in terms of oxide, based on the total mass of the silico-phospho-aluminate molecular sieve, and specifically, for example, can be any value in the range constituted by any two of the point values 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%. With this preferred embodiment, increasing the content of silicon in the silico-phospho-aluminate molecular sieve can further improve the activity of the catalyst.

[0023] According to the present application, preferably, the mass ratio of aluminum to phosphorus in the silico-phospho-aluminate molecular sieve is 1:1.25-1.55, in terms of oxide.

[0024] Since the silico-phospho-aluminate molecular sieve is stable in nature, the content of each component in the silico-phospho-aluminate molecular sieve in the catalyst of the present application can be considered the same as that of the silico-phospho-aluminate molecular sieve raw material.

[0025] The content of each component in the silico-phospho-aluminate molecular sieve raw material of the present application is measured by the ICP-OES (inductively coupled plasma emission spectrometer) method.

[0026] The present application has a wide selection range for the type of the silico-phospho-aluminate molecular sieve, and preferably, the silico-phospho-aluminate molecular sieve is SAPO-34 molecular sieve and / or SAPO-47, and more preferably, is SAPO-34 molecular sieve. With the above specific type of molecular sieve, the selectivity of monomethylamine and dimethylamine is more improved.

[0027] In the present application, the active component is magnesium and / or zinc, and preferably is magnesium. With this preferred embodiment, the selectivity of monomethylamine and dimethylamine is more improved.

[0028] According to the present application, preferably, the carrier further contains a binder.

[0029] According to the present application, preferably, the binder is silicon dioxide and / or aluminum oxide, and more preferably is silicon dioxide. With this preferred embodiment, the strength of the catalyst is improved and the generation of trimethylamine is inhibited.

[0030] According to the present application, preferably, the mass content of the binder is 10-40%, preferably 16-35%, more preferably 18-26%, specifically, for example, can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% and any value in the range constituted by any two of these point values.

[0031] In the catalyst described in the present application, the content of each component adds up to 100%.

[0032] The content of each component of the catalyst described in the present application is measured by the amount of feed.

[0033] The preparation method of the catalyst described in the present application is not particularly limited, as long as the catalyst with the above composition can be prepared. In order to more clearly illustrate the preparation of the above catalyst, a specific preparation method is provided, and the present application is not limited thereto.

[0034] According to the present application, preferably, the preparation method of the catalyst comprises the following steps:

[0035] S1, mixing and forming a silico-phospho-aluminum molecular sieve with CHA structure and an optional binder precursor, then drying and first calcining to obtain a catalyst carrier;

[0036] S2, introducing an active component to the catalyst carrier.

[0037] Preferably, the silico-phospho-aluminum molecular sieve is a hydrogen-type silico-phospho-aluminum molecular sieve.

[0038] In the present application, the silico-phospho-aluminum molecular sieve can be commercially available or prepared according to conventional methods in the art, and the present application is not particularly limited thereto, as long as the silico-phospho-aluminum molecular sieve with the above composition is obtained.

[0039] The type of the binder precursor described in the present application can be a conventional selection in the art. The embodiment of the present application exemplarily uses silica sol.

[0040] In the mixing process of S1, a peptizing agent and a extrusion aid can be added or not.

[0041] The type and amount of the peptizing agent and the extrusion aid are not particularly limited in the present application, and can be a conventional selection in the art, which is subject to the subsequent smooth molding.

[0042] In the mixing process of S1, water can be added or not. The amount of water is not particularly limited in the present application, and is ensured to be suitable for subsequent molding.

[0043] The molding method of S1 is not particularly limited in the present application, and at least one of the commonly used molding methods in the art, such as extrusion molding, spray molding, round molding and tablet molding, can be used. The present application preferably uses extrusion molding.

[0044] The drying of S1 can be performed by a conventional method in the art. The drying of S1 can be oven drying or vacuum drying. Preferably, the conditions of the drying of S1 include a temperature of 80-120℃ and a time of 2-12 hours.

[0045] According to a specific embodiment of the present application, the molding is first air-dried at room temperature, and then dried.

[0046] The conditions of the first calcination of S1 are not particularly limited in the present application, and can be performed according to conventional methods in the art. Preferably, the conditions of the first calcination of S1 include a temperature of 500-600℃ and a time of 2-10 hours. The first calcination is generally performed in an air atmosphere, which can include a flowing atmosphere or a static atmosphere.

[0047] The method for introducing the active component onto the catalyst carrier is not particularly limited in the present application, and various methods conventionally used in the art can be used. The present application preferably uses an impregnation method.

[0048] According to the present application, preferably, the process of S2 includes impregnating the carrier in an impregnation solution containing a compound of the active component, and then drying and second calcination.

[0049] The impregnation method is not particularly limited in the present application, and the impregnation method can be excess liquid impregnation or equal volume impregnation, etc. according to the amount of the impregnation solution.

[0050] The number of impregnations is not particularly limited in the present application, and the impregnation can be performed once or multiple times, as long as the mass content of the active component in the catalyst is within the above range.

[0051] The temperature of the impregnation is not particularly limited in the present application, and can be performed according to conventional methods, such as room temperature. The time of the impregnation is also not particularly limited in the present application, as long as the required amount of the active component can be loaded on the catalyst carrier. When the required amount and conditions of the impregnation are determined, the appropriate impregnation time can be easily selected. The environment of the impregnation is not particularly limited in the present application, and can be performed under a sealed condition or in an open environment according to conventional methods in the art.

[0052] The kind of the active component-containing compound is not particularly limited, and can be selected according to the prior art. Preferably, the active component-containing compound is at least one of nitrate, chloride and sulfate of the active component.

[0053] Preferably, the concentration of the impregnation solution of the active component-containing compound is 0.05-0.3 g / mL.

[0054] The kind of the solvent in the impregnation solution of the active component-containing compound is not particularly limited, and can be selected according to the prior art. Preferably, water is used as the solvent in the embodiment of the present application.

[0055] The drying in S2 can be performed by using the method according to the prior art, and the conditions of the drying in S1 can be used.

[0056] According to the present application, preferably, the conditions of the second calcination include that the temperature is 500-650 ℃, and the time is 2-10 h.

[0057] The conditions of the methanol amination reaction are not particularly limited, and can be performed according to the prior art. Preferably, the conditions of the methanol amination reaction include that the temperature is 300-420 ℃, the pressure is 0.5-5 MPa, the volume space velocity is 1-20 h -1 .

[0058] According to the present application, preferably, the molar ratio of ammonia to methanol is 1.5-4.

[0059] According to the preferred embodiment, the catalyst provided by the present application has more excellent catalytic performance under the above conditions, and has higher conversion rate and selectivity.

[0060] In the present application, the "first" and "second" do not limit the substances and operations, and are only used to distinguish the substances introduced in different steps and the operations performed in different stages.

[0061] The present application will be described in detail by the following examples.

[0062] In the following examples, the grain size of the SAPO molecular sieve is obtained by scanning electron microscope observation.

[0063] The components of the catalyst are calculated by the amount of the raw materials.

[0064] The preparation example of the present application is used to illustrate the preparation of the catalyst of the present application

[0065] Preparation Example 1

[0066] Hydrogen-type SAPO-34 molecular sieve (dry base rate 75%, silicon oxide content 16.5 wt%, mass ratio of aluminum to phosphorus 1:1.38, and crystal grain size 500-600 nm) was mixed with silica sol (40 wt% of silicon dioxide) and Echinochloa crusgalli powder (mass ratio of SAPO-34 molecular sieve to Echinochloa crusgalli powder 16:1 on a dry base) to obtain a mixture. The mixture was kneaded and extruded into strips, air-dried, dried at 110°C for 24 h, and then calcined at 550°C for 6 h to obtain a catalyst carrier.

[0067] A solution was prepared by dissolving 5 g of magnesium nitrate hexahydrate in 50 mL of water. The solution was added to the catalyst carrier, which was then dried at 110°C for 10 h and calcined at 550°C for 6 h. Catalyst A was prepared. The catalyst composition is shown in Table 1.

[0068] Preparation Example 2

[0069] Hydrogen-type SAPO-34 molecular sieve (dry base rate 80%, silicon oxide content 18.1 wt%, mass ratio of aluminum to phosphorus 1:1.45, and crystal grain size 500-600 nm) was mixed with silica sol (40 wt% of silicon dioxide) and Echinochloa crusgalli powder (mass ratio of SAPO-34 molecular sieve to Echinochloa crusgalli powder 12.5:1 on a dry base) to obtain a mixture. The mixture was kneaded and extruded into strips, air-dried, dried at 110°C for 12 h, and then calcined at 550°C for 6 h to obtain a catalyst carrier.

[0070] A solution was prepared by dissolving 23 g of magnesium nitrate hexahydrate in 70 mL of water. The solution was added to the catalyst carrier, which was then dried at 110°C for 10 h and calcined at 550°C for 6 h. Catalyst B was prepared. The catalyst composition is shown in Table 1.

[0071] Preparation Example 3

[0072] Preparation was performed according to the method of Preparation Example 1, except that SAPO-34 molecular sieve with a crystal grain size of 800-900 nm was used in the preparation of the catalyst carrier. The catalyst was recorded as C. The catalyst composition is shown in Table 1.

[0073] Preparation Example 4

[0074] Preparation was performed according to the method of Preparation Example 1, except that SAPO-34 molecular sieve with a silicon oxide content of 10.5 wt% and a mass ratio of aluminum to phosphorus 1:1.26 on an oxide basis was used in the preparation of the catalyst carrier. The catalyst was recorded as D. The catalyst composition is shown in Table 1.

[0075] Preparation Example 5

[0076] The procedure of Preparation Example 1 was followed except that instead of adding magnesium nitrate hexahydrate, an equal mass of zinc nitrate hexahydrate was added as the metal oxide. The catalyst was labeled E. The catalyst composition is shown in Table 1.

[0077] Preparation Example 6

[0078] The procedure of Preparation Example 1 was followed except that the amount of magnesium nitrate was adjusted so that the mass content of magnesium oxide in the catalyst produced was 8.5%. The catalyst was labeled F. The catalyst composition is shown in Table 1.

[0079] Comparative Preparation Example 1

[0080] The procedure of Preparation Example 1 was followed except that instead of using SAPO-34 molecular sieve as the catalyst support, an equal mass of ZSM-5 molecular sieve was used. The catalyst was labeled G. The catalyst composition is shown in Table 1.

[0081] Comparative Preparation Example 2

[0082] The procedure of Preparation Example 1 was followed except that instead of adding magnesium nitrate, an equal mass of sodium chloride was added as the metal oxide. The catalyst was labeled H. The catalyst composition is shown in Table 1.

[0083] Table 1

[0084]

[0085] Example 1

[0086] The catalyst A prepared in Preparation Example 1 was packed in a fixed bed reactor and subjected to a methanol amination reaction at a reaction temperature of 360°C, a volume space velocity of ammonia and methanol of 8 h -1 , a reaction pressure of 2 MPa, and a molar ratio of ammonia to methanol of 2. The reaction results after 3 h of reaction are shown in Table 2.

[0087] Examples 2-6, Comparative Examples 1-2

[0088] The procedure of Example 1 was followed except that the catalysts (B-H) of Preparation Examples 2-6 and Comparative Examples 1-2 were packed in a fixed bed reactor, respectively.

[0089] Example 7

[0090] The catalyst A prepared in Preparation Example 1 was packed in a fixed bed reactor and subjected to a methanol amination reaction at a reaction temperature of 390°C, a volume space velocity of ammonia and methanol of 15 h -1 , a reaction pressure of 2.8 MPa, and a molar ratio of ammonia to methanol of 1.5. The reaction results after 5 h of reaction are shown in Table 2.

[0091] Table 2

[0092]

[0093] As can be seen from the results in Table 2, the monomethylamine and dimethylamine obtained by the method of the present application have significantly higher selectivity.

[0094] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and belong to the protection scope of the present application.

Claims

1. A method for producing monomethylamine and dimethylamine, characterized in that: The method comprises: bringing methanol and ammonia into contact with a catalyst for reaction; the catalyst comprises a carrier and an active component supported on the carrier; the carrier comprises a silicon-phosphorus-aluminum molecular sieve with a CHA structure, and the active component is magnesium and / or zinc; Wherein, based on the total mass of the catalyst, the mass content of the active component calculated as oxide is 0.1-10%.

2. The method according to claim 1, wherein Based on the total mass of the catalyst, the mass content of the active component calculated as oxide is 1-7%; Preferably, based on the total mass of the catalyst, the mass content of the silicon-phosphorus-aluminum molecular sieve is 55-85%, preferably 60-80%.

3. The method according to claim 1 or 2, wherein: The crystal particle size of the silicon-phosphorus-aluminum molecular sieve is not greater than 1 μm, preferably 400-700 nm.

4. The method according to any one of claims 1 to 3, wherein: Based on the total mass of the silicon-phosphorus-aluminum molecular sieve, the mass content of silicon is 10-30%, preferably 15-22%, calculated as oxide; Preferably, in the silicon-phosphorus-aluminum molecular sieve, the mass ratio of aluminum to phosphorus, calculated as oxide, is 1:1.25-1.

55.

5. The method according to any one of claims 1 to 4, wherein: The silicon-phosphorus-aluminum molecular sieve is selected from SAPO-34 molecular sieve and / or SAPO-47 molecular sieve, preferably SAPO-34 molecular sieve; Preferably, the active ingredient is magnesium.

6. The method according to any one of claims 1 to 5, wherein: The carrier also contains a binder; Preferably, the binder is silica and / or alumina, more preferably silica; Preferably, based on the total mass of the catalyst, the mass content of the binder is 10-40%, preferably 16-35%.

7. The method according to any one of claims 1 to 6, wherein: The preparation method of the catalyst comprises the following steps: S1, mixing a silicon-phosphorus-aluminum molecular sieve having a CHA structure and an optional binder precursor to form a mixture, followed by drying and a first calcination to obtain a catalyst support; S2. Introducing active components onto the catalyst support.

8. The method according to claim 7, wherein: S1: The first calcination conditions include: a temperature of 500-600°C and a time of 2-10 hours.

9. The method according to claim 7, wherein: The S2 process comprises: impregnating the support in an impregnation solution containing a compound of an active component, followed by drying and a second calcination; Preferably, the compound of the active ingredient is selected from at least one of nitrate, chloride and sulfate of the active ingredient; Preferably, the second calcination conditions include: temperature of 500-650° C. and time of 2-10 h.

10. The method according to any one of claims 1 to 9, wherein: The conditions of the methanol amination reaction include: temperature of 300-420°C, pressure of 0.5-5 MPa, volume space velocity of 1-20 h -1 ; Preferably, the molar ratio of ammonia to methanol is 1.5-4.

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