Method for co-producing monoethylamine and acetonitrile

Abstract

The invention relates to the technical field of production of monoethylamine and acetonitrile by using ethylenediamine and refining and separation thereof, and discloses a method for co-production of monoethylamine and acetonitrile, which comprises the following steps: (S1) in the presence of a catalyst, diethylamine, hydrogen and ammonia gas are uniformly mixed and preheated, and then are subjected to an ammonolysis reactor reaction and gas-liquid separation, and a crude product obtained after gas-liquid separation passes through a monoethylamine refining tower to obtain a monoethylamine product; separating into a monoethylamine product at the top of the tower and a tower kettle product containing diethylamine and acetonitrile at the bottom of the tower; the catalyst comprises aluminum oxide modified by an SAPO-34 molecular sieve, Ni, Co, Pr and / or Nd, the content of Ni and Co is 15-40 wt%, and the molar ratio of Ni to Co is 1-8.5; (S2) separating a tower kettle product containing diethylamine and acetonitrile, which is led out by the monoethylamine refining tower, into a solvent-containing material flow at the tower top and an acetonitrile product at the tower kettle through an acetonitrile refining tower; according to the method, monoethylamine and acetonitrile products are produced at the same time through diethylamine ammonolysis reaction and rectification separation.

Description

Technical Field

[0001] This invention relates to the technical field of producing monoethylamine and acetonitrile using ethylenediamine and their purification and separation, specifically, to a method for co-producing monoethylamine and acetonitrile. Background Technology

[0002] Ethylamine, also known as aminoethane, is a colorless, flammable, volatile liquid with an ammonia odor. It is miscible with water, alcohols, and ethers in any proportion and is used in the manufacture of dyes, rubber accelerators, extractants, emulsifiers, insecticides, herbicides, and mineral processing agents. It is also widely used in the production of dyes, surfactants, antioxidants, and preservatives, and can be used to manufacture pesticides such as simazine and atrazine.

[0003] Currently, the main methods for synthesizing monoethylamine include ethylene ammoniation, chloroethane ammonolysis, acetonitrile hydrogenation, acetaldehyde ammoniation, and ethanol hydroammoniation.

[0004] The ammonolysis of chloroethane to produce monoethylamine produces hydrogen chloride as a byproduct, resulting in low raw material utilization and the generation of large amounts of chlorine-containing wastewater and salts. This process also causes severe equipment corrosion and environmental pollution, and has since been phased out.

[0005] The acetonitrile reduction method uses acetonitrile as a raw material and ammonia borane or hydrogen as a hydrogen source to prepare monoethylamine through liquid-phase hydrogenation reduction in the presence of catalysts such as metal oxides or Raney nickel. However, due to the high price of acetonitrile, its use is limited and large-scale production is difficult.

[0006] Compared to other methods, the hydroammoniation of ethanol is more economical due to the inexpensive and readily available ethanol raw material and the relatively safe and environmentally friendly overall reaction process. Currently, this method is almost universally used in China for the production of ethylamine products. The catalysts commonly used in this process are supported catalysts such as nickel and cobalt. These catalysts are mostly balanced catalysts with good catalytic performance. Therefore, the hydroammoniation process results in a relatively fixed ratio of various ethylamine products in the reaction products, with a yield ratio of approximately 2:5:3, and a relatively high proportion of diethylamine. However, the market demand for monoethylamine, diethylamine, and triethylamine differs, with relatively higher demand for monoethylamine and triethylamine. The excess diethylamine produced needs to be separated and returned to the reactor inlet to mix with fresh material before being recycled back into the alcohol amination reactor in large quantities to adjust the product ratio.

[0007] CN114315593 discloses a method for producing ethylamine with an adjustable product ratio. The method utilizes diethylamine produced from the product to further react with ethanol, ammonia, etc., to prepare triethylamine, thereby achieving an adjustable ethylamine product ratio. However, this method of extensively recycling diethylamine products significantly increases the overall energy consumption of the equipment, reduces its production efficiency, and also generates more byproducts, causing difficulties in subsequent separation and increasing economic and environmental pressures.

[0008] Acetonitrile is a widely used fine chemical product, used as an extractant, solvent, and raw material for the synthesis of pesticides. Currently, globally, acetonitrile is mainly obtained from the crude byproduct of acrylonitrile production via the ammoxidation of propylene, accounting for 2-3% of total acrylonitrile production. This production is unstable and highly dependent on the capacity of acrylonitrile plants. New acetonitrile production processes are attracting significant attention.

[0009] Currently, the main production technologies for acetonitrile include acrylonitrile by-product recovery, acetic acid ammoniation dehydration, ethanol dehydrogenation ammoniation, and monoethylamine dehydrogenation. Acrylonitrile by-product recovery suffers from limited capacity and difficulty in producing high-purity acetonitrile. Acetic acid ammoniation uses alumina as a catalyst, where acetic acid and ammonia first react at high temperatures (370-450℃) to form ammonium acetate. Ammonium acetate then dehydrates to produce acetamide, which is further dehydrated to yield acetonitrile.

[0010] CN11757320 discloses a method for preparing acetonitrile and co-producing acetamide via acetic acid ammoniation. This method controls the reaction temperature and process to adjust the product to be either acetamide or acetonitrile. However, the preparation of acetonitrile still faces problems such as high reaction temperature and difficulties in subsequent dehydration. Ethanol dehydrogenation ammoniation is currently a hot research topic. The process roughly involves the dehydrogenation of ethanol to aldehyde, ammoniation of the aldehyde to hydroxylamine, dehydration of the hydroxylamine to monoethylamine, and then dehydrogenation of the monoethylamine to acetonitrile, potentially generating byproducts such as butyronitrile and pyridine bases. This process typically involves reaction temperatures between 300-450℃, and subsequent purification is also difficult. Monoethylamine dehydrogenation directly dehydrogenates monoethylamine to produce acetonitrile.

[0011] CN101648888 and CN113620836 both disclose a method for preparing acetonitrile using the dehydrogenation of monoethylamine. Both methods employ a Cu-Zn-Al catalyst, with reaction temperatures ranging from 250-500℃ and reaction pressures from 0.01-2.0 MPa. This method is simple, produces no water during the reaction, and generates hydrogen as a byproduct, making it suitable for companies with monoethylamine as a raw material. To date, no technology has been found that simultaneously produces monoethylamine and acetonitrile using diethylamine.

[0012] In view of the various problems existing in the production of monoethylamine and acetonitrile, it is of great significance to research and develop a method for producing monoethylamine and acetonitrile using the diethylamine reaction. Summary of the Invention

[0013] The purpose of this invention is to overcome the deficiency in the prior art that there is no diethylamine reaction to simultaneously produce monoethylamine and acetonitrile, and to provide a method for co-producing monoethylamine and acetonitrile. This method utilizes the ammonolysis reaction of diethylamine and separates the products by distillation to simultaneously produce monoethylamine and acetonitrile.

[0014] To achieve the above objectives, the present invention provides a method for the co-production of monoethylamine and acetonitrile, wherein the method comprises:

[0015] (S1) Under the action of a supported catalyst, diethylamine, hydrogen and ammonia are mixed, preheated and then reacted in an ammonolysis reactor and separated into gas and liquid. The crude product is then separated into monoethylamine product at the top of the tower and diethylamine and acetonitrile product at the bottom of the tower.

[0016] The supported catalyst includes a support and an active component and an additive supported on the support. The support is alumina modified with SAPO-34 molecular sieve. The active component is Ni and Co. The additive is Pr and / or Nd. Based on the total weight of the supported catalyst, the total content of Ni and Co elements is 15-40 wt%, and the molar ratio of Ni / Co is 1-8.5.

[0017] (S2) The product from the bottom of the diethylamine and acetonitrile column, which was drawn from the monoethylamine purification column, is then separated into a solvent-containing stream at the top of the column and an acetonitrile product at the bottom of the column through an acetonitrile purification column.

[0018] Through the above technical solution, the method of the present invention utilizes the ammonolysis reaction of diethylamine and separates it by distillation to simultaneously produce monoethylamine and acetonitrile products. The reaction process does not generate water, and the subsequent product purification is relatively easy. In addition, the extraction ratio of monoethylamine and acetonitrile products can be adjusted by changing the process conditions, making the equipment more flexible. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of the method for co-producing monoethylamine and acetonitrile according to the present invention. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] As previously stated, the present invention provides a method for the co-production of monoethylamine and acetonitrile, wherein the method comprises:

[0022] (S1) Under the action of a supported catalyst, diethylamine, hydrogen and ammonia are mixed, preheated and then reacted in an ammonolysis reactor and separated into gas and liquid. The crude product is then separated into monoethylamine product at the top of the tower and diethylamine and acetonitrile product at the bottom of the tower.

[0023] The supported catalyst includes a support and an active component and an additive supported on the support. The support is alumina modified with SAPO-34 molecular sieve. The active component is Ni and Co. The additive is Pr and / or Nd. Based on the total weight of the supported catalyst, the total content of Ni and Co elements is 15-40 wt%, and the molar ratio of Ni / Co is 1-8.5.

[0024] (S2) The product from the bottom of the diethylamine and acetonitrile column, which was drawn from the monoethylamine purification column, is then separated into a solvent-containing stream at the top of the column and an acetonitrile product at the bottom of the column through an acetonitrile purification column.

[0025] According to the present invention, the top temperature of the monoethylamine refining column is 10-30°C, and the top pressure is 0.05-0.2 MPa; in the present invention, the theoretical number of trays of the monoethylamine refining column is 45-60, and the feed inlet is located in the lower middle part; preferably, the top temperature of the monoethylamine refining column is 18-20°C, and the top pressure is 0.9-0.15 MPa; in the present invention, the theoretical number of trays of the monoethylamine refining column is 52-58, and the feed inlet is located on the 32nd-35th tray.

[0026] According to the present invention, the top temperature of the acetonitrile refining column is 60-110℃, and the top pressure is 0.05-0.2MPa; in the present invention, the theoretical number of trays of the acetonitrile refining column is 30-50, and the feed inlet is located at the top; preferably, the top temperature of the acetonitrile refining column is 60-65℃, and the top pressure is 0.15-0.2MPa; the theoretical number of trays of the acetonitrile refining column is 38-45, and the feed inlet is located on the 5th-10th tray.

[0027] According to the present invention, in order to achieve better technical effects, diethylamine, hydrogen and ammonia are mixed, preheated and then introduced into a reactor, and reacted under the action of a catalyst to obtain a crude product containing monoethylamine and acetonitrile; the specific reaction conditions include: a reaction temperature of 180-300℃ and a reaction pressure of 0.1-10MPa; preferably, a reaction temperature of 200-270℃ and a reaction pressure of 0.5-8MPa; more preferably, a reaction temperature of 220-245℃ and a reaction pressure of 1.5-5MPa.

[0028] According to the present invention, the feed liquid hourly space velocity of diethylamine is 0.05 m. 3 / (m 3 ·h)–1m 3 / (m 3 ·h), preferably 0.1m 3 / (m 3 ·h)–0.6m 3 / (m 3 ·h), more preferably 0.3m 3 / (m 3 ·h)-0.5m 3 / (m 3 ·h).

[0029] According to the present invention, ammonia is preheated to liquid ammonia. In the present invention, the molar ratio of diethylamine:hydrogen:liquid ammonia is 1:(0.1-5):(5-100), preferably 1:(0.2-2):(10-80), and more preferably 1:(0.5-1):(37-62).

[0030] According to the present invention, the method further includes:

[0031] (1) Reaction: Diethylamine, hydrogen and ammonia are mixed, preheated and then introduced into an ammonolysis reactor. The reaction is carried out under the action of a catalyst to obtain a crude product containing monoethylamine and acetonitrile.

[0032] (2) Deammoniation: The crude product containing at least part of monoethylamine and acetonitrile after gas-liquid separation is separated into a top product containing liquid ammonia and a bottom product containing monoethylamine and acetonitrile by a deammoniation tower.

[0033] (3) Monoethylamine purification: The product in the bottom of the column containing monoethylamine and acetonitrile drawn from the deammoniation column is separated into monoethylamine product at the top of the column and diethylamine and acetonitrile product in the bottom of the column by passing it through the monoethylamine purification column.

[0034] (4) Diethylamine purification: The product in the bottom of the column containing diethylamine and acetonitrile drawn from the monoethylamine purification column is separated into diethylamine at the top of the column and a product in the bottom of the column containing triethylamine and acetonitrile by passing it through the diethylamine purification column.

[0035] (5) Triethylamine purification: The product in the bottom of the diethylamine purification tower containing triethylamine and acetonitrile is passed through the triethylamine purification tower, and a solvent is introduced into the triethylamine purification tower at the same time to separate the triethylamine product in the bottom of the tower and the product in the top of the tower containing solvent and acetonitrile.

[0036] (6) Liquid-liquid separator: The product from the bottom of the triethylamine purification tower containing solvent and acetonitrile is fed into the liquid-liquid separator. After separation and enrichment, the upper layer with a higher solvent concentration is returned to the triethylamine purification tower, and the lower layer with a higher acetonitrile concentration is fed into the subsequent acetonitrile purification tower.

[0037] (7) Acetonitrile purification tower: The above-mentioned stream with a high concentration of acetonitrile is passed through the acetonitrile purification tower to separate the solvent-containing stream at the top of the tower and the high-purity acetonitrile product at the bottom of the tower.

[0038] According to the present invention, the top temperature of the deammoniation tower is 20-30℃ and the top pressure is 0.8-1.2MPa; in the present invention, the theoretical number of trays of the deammoniation tower is 42-65, and the feed inlet is located in the lower middle part; preferably, the top temperature of the deammoniation tower is 23-25℃ and the top pressure is 0.9-1.1MPa; in the present invention, the theoretical number of trays of the deammoniation tower is 52-60, and the feed inlet is located on the 29th-35th tray.

[0039] According to the present invention, the top temperature of the diethylamine refining column is 45-70°C, and the top pressure is 0.05-0.2 MPa; in the present invention, the theoretical number of trays of the diethylamine refining column is 50-70, and the feed inlet is located in the lower middle part; preferably, the top temperature of the diethylamine refining column is 49-55°C, and the top pressure is 0.1-0.16 MPa; in the present invention, the theoretical number of trays of the diethylamine refining column is 57-65, and the feed inlet is located on the 33rd-39th tray.

[0040] According to the present invention, the top temperature of the triethylamine refining column is 54-65°C, and the top pressure is 0.1-0.3 MPa; in the present invention, the theoretical number of plates of the triethylamine refining column is 50-70, the feed inlet is located in the lower middle part, and the solvent feed inlet is located in the upper middle part; preferably, the top temperature of the triethylamine refining column is 56-62°C, and the top pressure is 0.15-0.2 MPa; in the present invention, the theoretical number of plates of the triethylamine refining column is 55-62, the feed inlet is located on the 32nd-38th plate, and the solvent feed inlet is located on the 9th-10th plate.

[0041] According to the present invention, the operating temperature of the liquid-liquid separator is 50-70°C, and the operating pressure is 0.05-0.2 MPa; preferably, the operating temperature of the liquid-liquid separator is 56-63°C, and the operating pressure is 0.12-0.15 MPa. In the present invention, the solvent in step (6) is selected from one or more of n-pentane, n-hexane, cyclohexane, 2-methylpentane, and 3-methylpentane. More preferably, the solvent is 2-methylpentane and / or 3-methylpentane.

[0042] According to the present invention, in order to better optimize and improve the multifunctionality of the above-mentioned catalyst, such as the dehydrogenation, hydrogenation or ammoniation functions of the catalyst, preferably, the total content of Ni and Co elements is 15-40 wt% based on the total weight of the supported catalyst, and the molar ratio of Ni / Co is 3-7; more preferably, the total content of Ni and Co elements is 20-35 wt% based on the total weight of the supported catalyst.

[0043] According to the present invention, in order to improve the selectivity of the target products monoethylamine and acetonitrile during the reaction, the catalyst contains an auxiliary agent, preferably Pr or Nd, more preferably Nd; and even more preferably, the content of the auxiliary agent is 0.5-3 wt% based on the total weight of the supported catalyst.

[0044] According to the present invention, the catalyst support, also known as a carrier, is an essential component of a supported catalyst. The catalytically active component is loaded onto the surface of the support. The support primarily serves to support the active component, giving the catalyst specific physical properties, while the support itself generally does not possess catalytic activity. However, the support allows the active component to be dispersed on its surface, achieving a higher specific surface area and improving the catalytic efficiency per unit mass of active component. Based on the inventors' research, preferably, the catalyst support used in the present invention is SAPO-34 molecular sieve-modified alumina, wherein the alumina content in the support is 50-90 wt% of the total weight of the support; preferably, the alumina content in the support is 60-80 wt% of the total weight of the support.

[0045] According to the present invention, alumina is a well-known amphoteric oxide, possessing both acidic and basic sites, but its surface properties vary depending on the production method, calcination, and processing of the support raw material. Furthermore, the inventors have discovered that other substances can be added during the support preparation process to modify certain surface properties. For example, adding SiO2, ZrO2, molecular sieves, zeolites, and acid-base precursors to Al2O3 can improve certain support characteristics. In the technical solution of the present invention, the support can also be treated with fluorine-containing compounds, phosphorus-containing compounds, sulfur-containing compounds, or selenium-containing compounds. These compounds can also be added during the support forming process or catalyst forming process for modification. Additionally, other forms of these compounds or corresponding elements can be introduced during the production of the support raw material. These methods of modifying the support are merely illustrative and not limited thereto. The inventors have found that adding an appropriate amount of SAPO-34 molecular sieve further improves the catalyst performance of the present invention. Preferably, the SAPO-34 molecular sieve has a SiO2 / (SiO2+Al2O3+P2O5) ratio of 0.09-0.12, more preferably 0.11, a grain size of 1-2 μm, more preferably 1.2, and a specific surface area >600 m². 2 / g, preferably 610m 2 / g.

[0046] The shape and size of the catalyst of the present invention can be customized arbitrarily, such as spherical, strip, columnar, ring, etc., with the size mostly between 0.3-6 mm, more preferably between 0.5-4 mm. This size requirement is mainly based on the fixed bed reactor design of the present invention to facilitate installation, reduce bed pressure, and other requirements.

[0047] In this invention, it should be noted that there are many methods for preparing the support, such as precipitation, impregnation, sol-gel methods, etc., with impregnation being preferred. Those skilled in the art can implement one of these methods to prepare the catalyst according to the catalyst formulation of this invention. For example, when preparing the catalyst using the impregnation method, the active and auxiliary components required to be loaded on the support are preferably soluble salt solutions of the components, such as aqueous solutions of nitrates, formates, or oxalates. In this invention, preferably, one or more of nickel nitrate, nickel acetate, and cobalt nitrate can be used.

[0048] The impregnation of the support with metal salt solution can be carried out in any desired order, or multiple impregnations can be performed continuously using a solution containing one or more metal salts. After impregnation, the support needs to be dried at a specific temperature, preferably 80-150°C. The drying time can be set according to the specific temperature, material quantity, and equipment performance, ensuring that the moisture content of the dried support does not affect subsequent calcination; no specific limit is placed on the drying time. The dried catalyst precursor needs to be calcined at a specific temperature to decompose the salts of the desired supported components into oxides. The calcination temperature is preferably 150-500°C, more preferably 300-500°C, for 2-6 hours. If multiple impregnations are performed, it is best to perform drying and calcination after each impregnation. The final oxidized catalyst needs to be reduced to acquire catalytic activity. The preferred reduction temperature for the catalyst is 150-500℃, more preferably 200-450℃. The gas used for reduction can be pure hydrogen or a mixed gas, such as a mixture of hydrogen and nitrogen. During reduction, the reduction temperature can be gradually increased, but the temperature rise should not be too rapid, for example, not exceeding 30℃ / hour. Of course, other methods can also be used to reduce the catalyst, such as irradiation reduction.

[0049] According to a particularly preferred embodiment of the present invention, such as Figure 1 As shown, a method for co-producing monoethylamine and acetonitrile includes:

[0050] (1) Reaction: Diethylamine, recycled material, hydrogen and ammonia are mixed, preheated and then introduced into the reactor. Under the action of the catalyst, a crude product containing monoethylamine and acetonitrile is obtained. The mixed product from the reactor is cooled and separated into crude monoethylamine and acetonitrile products and hydrogen-containing gas after gas-liquid separation. The gas is recycled.

[0051] (2) Deammoniation: At least part of the crude product containing monoethylamine and acetonitrile is sent to the deammoniation tower to separate it into a top product containing liquid ammonia and a bottom product containing monoethylamine and acetonitrile.

[0052] (3) Monoethylamine purification: The product from the bottom of the deammoniation tower containing monoethylamine and acetonitrile is sent to the monoethylamine purification tower to separate the monoethylamine product at the top of the tower and the bottom product containing diethylamine and acetonitrile.

[0053] (4) Diethylamine purification: The bottom product of the monoethylamine purification tower containing diethylamine and acetonitrile is sent to the diethylamine purification tower to separate diethylamine at the top of the tower and bottom product containing triethylamine and acetonitrile.

[0054] (5) Triethylamine purification: The product from the bottom of the diethylamine purification tower containing triethylamine and acetonitrile is sent to the triethylamine purification tower, and a solvent is introduced into the triethylamine purification tower to separate the triethylamine product at the bottom of the tower and the product at the top of the tower containing solvent and acetonitrile.

[0055] (6) Liquid-liquid separator: The product from the bottom of the triethylamine refining tower containing solvent and acetonitrile is passed into the liquid-liquid separator. After separation and enrichment, the upper layer with a higher solvent concentration is returned to the triethylamine refining tower, and the lower layer with a higher acetonitrile concentration is sent to the subsequent acetonitrile refining tower.

[0056] (7) Acetonitrile purification tower: The above-mentioned stream with a high concentration of acetonitrile is sent to the acetonitrile purification tower to separate the solvent-containing stream at the top of the tower and the high-purity acetonitrile product at the bottom of the tower. The solvent-containing stream is then recycled to the liquid-liquid separator.

[0057] The circulating materials come from the top product of the deammoniation tower containing liquid ammonia, the unreacted diethylamine at the top of the diethylamine refining tower, and the hydrogen separated from the gas-liquid separator after the reactor.

[0058] The present invention will be described in detail below through embodiments.

[0059] In the following examples and comparative examples:

[0060] The specific mass composition of the catalyst was determined by semi-quantitative X-ray fluorescence analysis:

[0061] SAPO-34 raw material is a commercially available product from Beijing Innocare Technology Co., Ltd. (In the embodiments and / or comparative examples of this invention, SiO2 / (SiO2+Al2O3+P2O5) is 0.11, grain size is 1.2μm, and specific surface area is 610m²). 2 / g, sodium content is 0.007wt%;

[0062] The modified alumina carrier was prepared by extrusion molding of boehmite and SAPO-34. The boehmite was a commercially available product from Guangxi Yulin Sida Powder Co., Ltd. (prepared by aluminum alkoxide method, BET≥240m). 2 / g, pore volume ≥0.80ml / g, colloidal index ≥75%; preferably, in the embodiments and / or comparative examples of the present invention, it is prepared by the aluminum alkoxide method, BET 245m2 / g, pore volume 0.88ml / g, colloidal index 75%;

[0063] All metal salts used in the preparation of the catalyst were analytical grade nitrates, purchased from Beijing Innocare Technology Co., Ltd.

[0064] Example 1

[0065] In this embodiment, the catalyst has the following specific mass content composition: 21.4 wt% nickel, 5.22 wt% cobalt, and the molar ratio of Ni / Co is 4.1; 0.73 wt% neodymium, and the balance is γ-Al2O3 support modified with SAPO-34 molecular sieve, wherein the Al2O3 content is 72.5 wt% of the total support. The catalyst is prepared by equal volume impregnation method.

[0066] A method for co-producing monoethylamine and acetonitrile includes the following steps:

[0067] (1) Reaction: Diethylamine, hydrogen, and ammonia were mixed, preheated, and then introduced into a reactor. Under the action of a catalyst, a crude product containing monoethylamine and acetonitrile was obtained. The specific reaction conditions were: reaction pressure 1.5 MPa, reaction temperature 245 °C, and liquid hourly space velocity of diethylamine 0.5 m / s. 3 / (m 3 •h), the molar ratio of diethylamine:hydrogen:liquid ammonia is 1:0.55:37.5;

[0068] (2) Deammoniation: The crude product containing at least part of monoethylamine and acetonitrile after gas-liquid separation is sent to the deammoniation tower to separate it into a top product containing liquid ammonia and a bottom product containing monoethylamine and acetonitrile; the theoretical number of trays of the deammoniation tower is 60, the feed inlet is located on the 35th tray, the top temperature is 23.4℃, and the top pressure is 0.9MPa;

[0069] (3) Monoethylamine refining: The product from the bottom of the deammoniation tower containing monoethylamine and acetonitrile is sent to the monoethylamine refining tower to separate the monoethylamine product at the top of the tower and the product from the bottom of the tower containing diethylamine and acetonitrile; the monoethylamine refining tower has a theoretical number of 52 plates, the feed inlet is located on the 32nd plate, the temperature at the top of the tower is 18.6℃, and the pressure at the top of the tower is 0.09MPa;

[0070] (4) Diethylamine purification: The bottom product of the monoethylamine purification tower containing diethylamine and acetonitrile is sent to the diethylamine purification tower to separate diethylamine at the top of the tower and the bottom product containing triethylamine and acetonitrile; the theoretical number of plates of the diethylamine purification tower is 65, the feed inlet is located at the 39th plate, the top temperature of the tower is 49.5℃, and the top pressure of the tower is 0.16MPa;

[0071] (5) Triethylamine purification: The bottom product of the diethylamine purification tower containing triethylamine and acetonitrile is sent to the triethylamine purification tower. At the same time, 2-methylpentane is introduced into the triethylamine purification tower to separate the triethylamine product in the bottom of the tower and the top product containing 2-methylpentane and acetonitrile. The theoretical number of plates of the triethylamine purification tower is 62, the feed inlet is located on the 38th plate, the feed inlet of 2-methylpentane is located on the 9th plate, the top temperature is 56.3℃, and the top pressure is 0.15MPa.

[0072] (6) Liquid-liquid separator: The product from the bottom of the triethylamine refining tower containing 2-methylpentane and acetonitrile is passed into the liquid-liquid separator. After separation and enrichment, the upper layer with a higher concentration of 2-methylpentane is returned to the triethylamine refining tower, and the lower layer with a higher concentration of acetonitrile is sent to the subsequent acetonitrile refining tower. The operating temperature of the liquid-liquid separator is 56.0℃ and the operating pressure is 0.15MPa.

[0073] (7) Acetonitrile refining tower: The above-mentioned stream with a high acetonitrile concentration is sent to the acetonitrile refining tower to separate the stream containing 2-methylpentane at the top of the tower and the high-purity acetonitrile product at the bottom of the tower. The theoretical number of trays of the acetonitrile refining tower is 45, the feed inlet is located on the 10th tray, the top temperature of the tower is 60.2℃, and the top pressure of the tower is 0.15MPa.

[0074] Table 1 shows the specific composition of each reaction stream in the above steps.

[0075] After the reaction stabilized, samples were taken for analysis. The reaction results are shown in Table 3.

[0076] Table 1

[0077]

[0078] Example 2

[0079] In this embodiment, the catalyst has the following specific mass composition: 27.2 wt% nickel, 4.09 wt% cobalt, and a Ni / Co molar ratio of 6.65; 1.26 wt% neodymium, and the balance is a γ-Al2O3 support modified with SAPO-34 molecular sieve, wherein the Al2O3 content is 68.6 wt% of the total support. The catalyst is prepared by an equal-volume impregnation method.

[0080] A method for co-producing monoethylamine and acetonitrile includes the following steps:

[0081] (1) Reaction: Diethylamine, hydrogen, and ammonia were mixed, preheated, and then introduced into a reactor. Under the action of a catalyst, a crude product containing monoethylamine and acetonitrile was obtained. The specific reaction conditions were: reaction pressure 5.0 MPa, reaction temperature 221℃, and liquid hourly space velocity of diethylamine 0.3 m / s. 3 / (m 3•h), the molar ratio of diethylamine:hydrogen:liquid ammonia is 1:1:62;

[0082] (2) Deammoniation: At least a portion of the crude product containing monoethylamine and acetonitrile after gas-liquid separation is sent to the deammoniation tower to separate it into a top product containing liquid ammonia and a bottom product containing monoethylamine and acetonitrile; the theoretical number of trays of the deammoniation tower is 52, the feed inlet is located on the 29th tray, the top temperature is 25.1℃, and the top pressure is 1.1MPa;

[0083] (3) Monoethylamine purification: The product from the deammoniation tower containing monoethylamine and acetonitrile is sent to the monoethylamine purification tower to separate the monoethylamine product at the top of the tower and the product from the bottom of the tower containing diethylamine and acetonitrile; the monoethylamine purification tower has a theoretical number of 58 plates, the feed inlet is located on the 35th plate, the temperature at the top of the tower is 24.4℃, and the pressure at the top of the tower is 0.15MPa;

[0084] (4) Diethylamine purification: The bottom product of the monoethylamine purification tower containing diethylamine and acetonitrile is sent to the diethylamine purification tower to separate diethylamine at the top of the tower and the bottom product containing triethylamine and acetonitrile; the theoretical number of plates of the diethylamine purification tower is 57, the feed inlet is located on the 33rd plate, the top temperature of the tower is 55.1℃, and the top pressure of the tower is 0.10MPa;

[0085] (5) Triethylamine purification: The bottom product of the diethylamine purification tower containing triethylamine and acetonitrile is sent to the triethylamine purification tower. At the same time, 3-methylpentane is introduced into the triethylamine purification tower to separate the triethylamine product in the bottom of the tower and the top product containing 3-methylpentane and acetonitrile. The theoretical number of plates of the triethylamine purification tower is 55, the feed inlet is located on the 32nd plate, the feed inlet of 3-methylpentane is located on the 9th plate, the top temperature is 62.0℃, and the top pressure is 0.21MPa.

[0086] (6) Liquid-liquid separator: The product from the bottom of the triethylamine refining tower containing 3-methylpentane and acetonitrile is passed into the liquid-liquid separator. After separation and enrichment, the upper layer with a higher concentration of 3-methylpentane is returned to the triethylamine refining tower, and the lower layer with a higher concentration of acetonitrile is sent to the subsequent acetonitrile refining tower. The operating temperature of the liquid-liquid separator is 63.0℃ and the operating pressure is 0.12MPa.

[0087] (7) Acetonitrile refining tower: The above-mentioned stream with a high acetonitrile concentration is sent to the acetonitrile refining tower to separate the stream containing 3-methylpentane at the top of the tower and the high-purity acetonitrile product at the bottom of the tower. The theoretical number of trays of the acetonitrile refining tower is 38, the feed inlet is located on the 5th tray, the top temperature of the tower is 63.5℃, and the top pressure of the tower is 0.20MPa.

[0088] Table 2 shows the specific composition of each reactant stream in the above steps.

[0089] After the reaction stabilized, samples were taken for analysis. The reaction results are shown in Table 3.

[0090] Table 2

[0091]

[0092]

[0093] Example 3

[0094] The co-production of monoethylamine and acetonitrile was carried out using the same method as in Example 1, except that a different catalyst was used. Specifically, the catalyst used in Example 3 consisted of: 20.5 wt% nickel, 6.31 wt% cobalt, with a Ni / Co molar ratio of 3.25; 1.12 wt% neodymium, and the balance being a γ-Al₂O₃ support modified with SAPO-34 molecular sieve, wherein the Al₂O₃ content was 63.5 wt% of the total support. The catalyst was prepared by an equal-volume impregnation method.

[0095] 100 mL of the solution was placed in the reactor and activated with hydrogen at 250°C for 2 hours. The temperature was then lowered to 200°C, and the system pressure was increased to 7.5 MPa using hydrogen. Ammonia, after being preheated and mixed with hydrogen, was then metered into the reactor using a metering pump. Diethylamine was also metered into the reactor. The three reacted through a catalyst bed under the following conditions: a molar ratio of hydrogen to liquid ammonia to diethylamine of 1:40:1, and a liquid hourly space velocity (LHSV) of 0.25 h⁻¹. -1 After the reaction stabilized, samples were taken for analysis. The reaction results are shown in Table 3.

[0096] Example 4

[0097] The same method as in Example 1 was used to co-produce monoethylamine and acetonitrile, except that a different catalyst was used. Specifically, the catalyst used in Example 3 consisted of 16.56 wt% nickel, 4.25 wt% cobalt, and a Ni / Co molar ratio of 3.9; 0.75 wt% neodymium, with the balance being a γ-Al2O3 support modified with SAPO-34 molecular sieve, wherein the Al2O3 content was 76.2 wt% of the total support. The catalyst was prepared by an equal-volume impregnation method.

[0098] The catalyst evaluation method was the same as in Example 3, and the results are shown in Table 3.

[0099] Example 5

[0100] The same method as in Example 1 was used to co-produce monoethylamine and acetonitrile, except that a different catalyst was used. Specifically, the catalyst used in Example 3 was: 21.82 wt% nickel, 5.81 wt% cobalt, with a Ni / Co molar ratio of 3.76; 1.02 wt% neodymium, and the balance being a γ-Al2O3 support modified with SAPO-34 molecular sieve, wherein the Al2O3 content was 69.8 wt% of the total support. The catalyst was prepared by an equal-volume impregnation method.

[0101] The catalyst evaluation method was the same as in Example 3, and the results are shown in Table 3.

[0102] Comparative Example 1

[0103] The same method as in Example 1 was used to co-produce monoethylamine and acetonitrile, except that a different catalyst was used. Specifically, the catalyst used in Comparative Example 1 consisted of 13.12 wt% nickel, 1.45 wt% cobalt, and a Ni / Co molar ratio of 9.05; 0.90 wt% neodymium, with the balance being a γ-Al2O3 support modified with SAPO-34 molecular sieve, wherein the Al2O3 content was 65.44 wt% of the total support. The catalyst was prepared by an equal-volume impregnation method.

[0104] The catalyst evaluation method was the same as in Example 3, and the results are shown in Table 3.

[0105] Comparative Example 2

[0106] The co-production of monoethylamine and acetonitrile was carried out using the same method as in Example 1, except that a different catalyst was used. Specifically, the catalyst used in Comparative Example 2 consisted of 14.50 wt% nickel, 9.85 wt% cobalt, and a Ni / Co molar ratio of 1.47; 0.68 wt% neodymium, with the balance being a γ-Al2O3 support modified with SAPO-34 molecular sieve, wherein the Al2O3 content was 50.86 wt% of the total support. The catalyst was prepared by an equal-volume impregnation method.

[0107] The catalyst evaluation method was the same as in Example 3, and the results are shown in Table 3.

[0108] Comparative Example 3

[0109] The same method as in Example 1 was used to co-produce monoethylamine and acetonitrile, except that a different catalyst was used. Specifically, the catalyst used in Comparative Example 3 was: 35.52 wt% nickel, 7.34 wt% cobalt, and a Ni / Co molar ratio of 4.84; 0.78 wt% neodymium, and the balance being a γ-Al2O3 support modified with SAPO-34 molecular sieve, wherein the Al2O3 content was 68.89 wt% of the total support. The catalyst was prepared by an equal-volume impregnation method.

[0110] The catalyst evaluation method was the same as in Example 3, and the results are shown in Table 3.

[0111] Table 3

[0112]

[0113] As can be seen from the above embodiments, the method of the present invention can simultaneously produce monoethylamine and acetonitrile products using the diethylamine ammonolysis reaction. The above embodiments are merely illustrative, and the application of this method is not limited to the diethylamine reaction example described above.

[0114] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for co-producing monoethylamine and acetonitrile, characterized in that, The method includes: (S1) Under the action of a supported catalyst, diethylamine, hydrogen and ammonia are mixed, preheated and then reacted in an ammonolysis reactor and separated into gas and liquid. The crude product is then separated into monoethylamine product at the top of the tower and diethylamine and acetonitrile product at the bottom of the tower. The supported catalyst includes a support and an active component and an additive supported on the support. The support is alumina modified with SAPO-34 molecular sieve. The active component is Ni and Co. The additive is Pr and / or Nd. Based on the total weight of the supported catalyst, the total content of Ni and Co elements is 15-40 wt%, and the molar ratio of Ni / Co is 1-8.

5. (S2) The product from the bottom of the diethylamine and acetonitrile column, which was drawn from the monoethylamine purification column, is then separated into a solvent-containing stream at the top of the column and an acetonitrile product at the bottom of the column through an acetonitrile purification column.

2. The method according to claim 1, wherein, The top temperature of the monoethylamine refining column is 10-30℃, and the top pressure is 0.05-0.2MPa.

3. The method according to claim 1 or 2, wherein, The acetonitrile refining column has a top temperature of 60-110℃ and a top pressure of 0.05-0.2MPa.

4. The method according to any one of claims 1-3, wherein, The conditions for reacting diethylamine, hydrogen, and ammonia in an ammonolysis reactor after mixing, preheating, and then reacting include: a reaction temperature of 180-300℃ and a reaction pressure of 0.1-10MPa. And / or, the feed liquid hourly space velocity for diethylamine is 0.05 m³ / s. 3 / (m 3 ·h)-1m 3 / (m 3 ·h); And / or, the molar ratio of diethylamine: hydrogen: liquid ammonia is 1:(0.1-5):(5-100).

5. The method according to claim 1, wherein, Based on the total weight of the supported catalyst, the total content of Ni and Co elements is 15-40 wt%, and the molar ratio of Ni / Co is 3-7; Preferably, the total content of Ni and Co elements is 20-35 wt%, based on the total weight of the supported catalyst.

6. The method according to claim 1, wherein, The auxiliary agent is Nd; And / or, based on the total weight of the supported catalyst, the content of the promoter is 0.5-3 wt%.

7. The method according to claim 1, wherein, The alumina content in the carrier is 50-90 wt% of the total weight of the carrier; Preferably, the alumina content in the carrier is 60-80 wt% of the total weight of the carrier.

8. The method according to claim 1 or 7, wherein, The SAPO-34 molecular sieve has a SiO2 / (SiO2+Al2O3+P2O5) ratio of 0.09-0.12, a grain size of 1-2 μm, and a specific surface area >600 m². 2 / g.

9. The method according to any one of claims 1-8, wherein, The method further includes: (1) Reaction: Diethylamine, hydrogen and ammonia are mixed, preheated and then introduced into an ammonolysis reactor. The reaction is carried out under the action of a catalyst to obtain a crude product containing monoethylamine and acetonitrile. (2) Deammoniation: The crude product containing at least part of monoethylamine and acetonitrile after gas-liquid separation is separated into a top product containing liquid ammonia and a bottom product containing monoethylamine and acetonitrile by a deammoniation tower. (3) Monoethylamine purification: The product in the bottom of the column containing monoethylamine and acetonitrile drawn from the deammoniation column is separated into monoethylamine product at the top of the column and diethylamine and acetonitrile product in the bottom of the column by passing it through the monoethylamine purification column. (4) Diethylamine purification: The product in the bottom of the column containing diethylamine and acetonitrile drawn from the monoethylamine purification column is separated into diethylamine at the top of the column and a product in the bottom of the column containing triethylamine and acetonitrile by passing it through the diethylamine purification column. (5) Triethylamine purification: The product in the bottom of the diethylamine purification tower containing triethylamine and acetonitrile is passed through the triethylamine purification tower, and a solvent is introduced into the triethylamine purification tower at the same time to separate the triethylamine product in the bottom of the tower and the product in the top of the tower containing solvent and acetonitrile. (6) Liquid-liquid separator: The product from the bottom of the triethylamine purification tower containing solvent and acetonitrile is fed into the liquid-liquid separator. After separation and enrichment, the upper layer with a higher solvent concentration is returned to the triethylamine purification tower, and the lower layer with a higher acetonitrile concentration is fed into the subsequent acetonitrile purification tower. (7) Acetonitrile purification tower: The above-mentioned stream with a high concentration of acetonitrile is passed through the acetonitrile purification tower to separate the solvent-containing stream at the top of the tower and the high-purity acetonitrile product at the bottom of the tower.

10. The method according to claim 9, wherein, The temperature at the top of the ammonia removal tower is 20-30℃, and the pressure at the top of the tower is 0.8-1.2MPa; And / or, the top temperature of the diethylamine refining column is 45-70℃, and the top pressure is 0.05-0.2MPa; And / or, the top temperature of the triethylamine refining column is 54-65℃, and the top pressure is 0.1-0.3MPa; And / or, the operating temperature of the liquid-liquid separator is 50-70℃, and the operating pressure is 0.05-0.2MPa.

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