Process for the production of n-octylamine in a tube

Abstract

The application belongs to the field of fine chemical industry, and particularly relates to a method for producing n-octylamine in a pipe. The application provides a method for producing n-octylamine in a pipe, which adopts a water-soluble homogeneous catalyst, and n-octyl aldehyde and ammonia water as raw materials to generate an amination reaction in a pipe reactor under a hydrogen atmosphere. The amination reaction includes two-step series reactions of dehydration and hydrogenation. N-octylamine is obtained. The water-soluble homogeneous catalyst is composed of a 3d metal salt, an EDTA type ligand, a promoter and water. The application has the advantages of high yield, low cost, simple process, no three-waste emissions and facilitation of industrialization expansion.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and particularly relates to a tubular method for producing n-octylamine. Background Art

[0002] n-Octylamine, the structural formula is as follows: Formula 1, molecular formula: C8H 19 N, abbreviated as octylamine in Chinese, is an important organic chemical intermediate and a high-grade fatty amine, widely used in the production of pesticides and medicines.

[0003]

[0004] In the currently reported prior art, the synthesis methods of n-octylamine are as follows:

[0005] Patent CN1962604 uses n-octanol and liquid ammonia as raw materials, using Ni-Cu / Al2O3 as a catalyst, to synthesize n-octylamine in a batch reactor. When the ammonia-to-alcohol molar ratio is 9, the reaction temperature is 190-220°C, and the reaction time is 2 hours, the yield is 89%. Patent CN102070460 reports a gas-liquid-solid three-phase amination reaction using n-octanol and liquid ammonia as raw materials, diatomaceous earth-supported nickel as a catalyst, and a fixed-bed reactor in the presence of hydrogen, achieving a yield of 94%. Patents CN103657682 and CN103664633 also report similar reactions. Patent CN112125807 reports a loop reactor using n-octanoic acid and liquid ammonia as the main raw materials, hydrogen as a reducing agent, to generate n-octanonitrile at high temperature and in the presence of a catalyst. The octanonitrile is then hydrogenated in the presence of a catalyst to produce n-octylamine. The addition of sulfonates can improve the efficiency of condensation; Patent CN111939925 reports that in a microchannel reactor, n-octanol and liquid ammonia are used as raw materials, hydrogen is used as a reducing agent, and alumina-loaded metal copper, nickel, platinum, chromium, and zinc are used as catalysts. The molar ratio of n-octanol to liquid ammonia is 1:1.5-3, the reaction temperature is controlled at 120°C, and the yield is controlled at 97%.

[0006] In Green Chem., 2020, 22, 7387, it was reported that n-octanal was used as raw material and a heterogeneous catalyst Ni / NiO@C-700-200-2h-EtOH was adopted. However, since it is a granular catalyst, it will clog the pipeline and cannot achieve continuous production.

[0007] The existing technology for synthesizing n-octylamine currently has the following problems:

[0008] The disadvantage of adopting a reactor is that the reaction temperature is too high, resulting in a short catalyst life and poor reaction selectivity, and the conversion rate is also low. The disadvantage of adopting a fixed-bed synthesis technology is that the requirements for equipment are high and the process operation is complicated, there is a poor heat transfer effect, and the preparation process of the catalyst is relatively complicated, and some catalysts require the participation of precious metals. Although improved by adopting a microchannel reaction device and continuous production has been achieved, it is still necessary to prepare a relatively complicated supported catalyst, and production is unstable, and the preparation process of the catalyst in each batch directly affects the product purity of each batch. In addition, in order to increase the conversion rate of n-octanol, the above method all needs to add excessive liquid ammonia, but greatly excessive liquid ammonia can produce excessive pressure under high temperature, and recovery is troublesome, increases equipment and production cost, and is also a kind of pollution to the environment. When using n-octanoic acid and liquid ammonia as raw materials, this method is due to the high reaction temperature, and the fatty acid is greatly affected by temperature on equipment corrosion, and the boiling point of octanoic acid is higher, which increases the subsequent separation difficulty, improves production cost, and seriously restricts the industrialization of this process. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for continuously preparing n-octylamine, which can realize continuous and stable production and improve production efficiency.

[0010] In order to solve the above technical problems, the present invention provides a tubular method for producing n-octylamine, which uses a water-soluble homogeneous catalyst, takes n-octanal and ammonia water as raw materials, and undergoes an amination reaction in a pipeline reactor under a hydrogen atmosphere. The amination reaction includes a two-step series reaction of dehydration and hydrogenation to obtain n-octylamine.

[0011] As an improvement of the tubular method for producing n-octylamine of the present invention, the method comprises the following steps:

[0012] 1) Pumping n-octanal, ammonia water, and a water-soluble homogeneous catalyst (catalyst solution) into a pipeline reactor at a mass flow rate ratio of 1-3:1:0.01-0.1 to enter a dehydration and hydrogenation reaction; hydrogen is simultaneously pumped into the pipeline reactor at a mass flow rate ratio of hydrogen to ammonia water of 0.1-0.4:1;

[0013] The reaction temperature of the pipeline reactor is 40 to 180° C. (preferably 80 to 120° C.), and the outlet back pressure valve of the pipeline reactor is controlled so that the reaction pressure of the pipeline reactor is 0.1 to 5 MPa (preferably 1.5 to 3 MPa), and the reaction time is 5 to 20 min (preferably 8 to 15 min);

[0014] 2) The product obtained from the dehydration and hydrogenation reaction is post-treated to obtain crude n-octylamine.

[0015] As a further improvement of the tubular method for producing n-octylamine of the present invention, the configuration method of the water-soluble homogeneous catalyst is:

[0016] The water-soluble homogeneous catalyst (catalyst solution) is composed of the following components in weight content: 0.5-10% (preferably 5-10%) of 3d metal salt, 5-30% (preferably 5-10%) of EDTA type ligand, 0.5-5% (preferably (3±0.3)%) of promoter and water as the balance;

[0017] The promoter is a protonic acid.

[0018] Promoters can accelerate the rate of hydrogenation reaction.

[0019] As a further improvement of the tubular method for producing n-octylamine of the present invention:

[0020] The 3d metal is at least one (i.e., one or more) of a sulfate or chloride of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn;

[0021] The EDTA-type ligand may be EDTA, EDTA-2Na, EDTA-4Na, CDTA, or at least one (i.e., one or more) having a similar coordination structure;

[0022] The protonic acid is at least one (ie, one or more) of formic acid, acetic acid, CF3SO3H, and HBF4.

[0023] As a further improvement of the tubular method for producing n-octylamine of the present invention:

[0024] The 3d metal is preferably ferrous sulfate or ferrous chloride.

[0025] The protonic acid is preferably HBF4.

[0026] As a further improvement of the tubular method for producing n-octylamine of the present invention: an alcohol solvent is added in step 1) to promote the dissolution of n-octanal as the substrate in water,

[0027] The alcohol solvent is at least one (i.e. one or more) of methanol, ethanol, and isopropanol;

[0028] The weight ratio of alcohol solvent to n-octanal is 0.01 to 0.2:1 (preferably 0.05 to 0.1:1).

[0029] As a further improvement of the tubular method for producing n-octylamine of the present invention:

[0030] The post-treatment of step 2) is as follows: extracting the product obtained from the dehydration and hydrogenation reaction with ethyl acetate, separating the phases, and removing the solvent (ethyl acetate) from the collected ethyl acetate layer containing the product to obtain crude n-octylamine.

[0031] The crude n-octylamine is then purified by vacuum distillation to obtain pure n-octylamine.

[0032] The process route of the present invention is as follows: n-octyl aldehyde and ammonia water are used as starting materials, and n-octylamine is prepared through two-step reactions of dehydration and hydrogenation in the presence of a water-soluble catalyst.

[0033] The term "preferred" as used herein refers to embodiments of the invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are unsuitable, nor is it intended to exclude other embodiments from the scope of the invention. All sources cited herein are commercially available.

[0034] The synthesis equation of n-octylamine of the present invention is as follows:

[0035]

[0036] In summary, the method for preparing n-octylamine of the present invention has the following technical advantages:

[0037] 1. Using readily available and inexpensive n-octanal and ammonia water as raw materials, the use of liquid ammonia is avoided, and the process route is more atom-economical, with low raw material consumption and environmental protection;

[0038] Explanation: Existing technologies use ammonia gas or liquid ammonia, which requires a high ammonia concentration because the catalysts are sensitive to water and easily deteriorate. However, the catalyst of the present invention is a water-soluble salt and is therefore more stable in water, thus avoiding the use of liquid ammonia.

[0039] 2. The pipeline reactor uses a water-soluble homogeneous catalyst. The catalyst is inexpensive, readily available, stable, and simple to operate. Complex catalyst preparation is unnecessary; only a specific ratio of catalyst needs to be prepared. The catalyst can also be easily separated and recycled (i.e., the aqueous catalyst solution can be recycled). This enables a continuous dehydration and hydrogenation process for producing n-octylamine. This process is more efficient than the existing batch process, avoids the separation and storage of intermediate materials, and operates under mild process conditions, promising promising industrial applications.

[0040] Note: The dehydration between octanal and ammonia to form imine is a spontaneous process.

[0041] 3. The present invention uses a water-soluble homogeneous catalyst, which completely avoids the problem of pipeline blockage and realizes continuous production.

[0042] 4. The present invention can realize the recycling and utilization of the catalyst aqueous solution.

[0043] In summary, compared with existing technologies, this invention offers high atom economy, with water as the only byproduct, resulting in a clean, zero-pollution process. Furthermore, the catalyst is readily available and recyclable, resulting in low cost. This process boasts high yield, low cost, simplicity, no waste, and is amenable to industrial scale-up. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0045] Figure 1 Schematic diagram of the device of the present invention. DETAILED DESCRIPTION

[0046] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto:

[0047] Device Example 1: A continuous pipeline device for preparing n-octylamine, including a pipeline reactor and various storage tanks, valves, pumps and corresponding connecting pipelines, its structure is as follows: Figure 1 As shown, the details are as follows:

[0048] The outlet of the n-octanal raw material tank is connected to the inlet of the stop valve 9 after passing through the stop valve 1, pump I, stop valve 4 in sequence;

[0049] The outlet of the ammonia raw material tank is connected to the inlet of stop valve 9 after passing through stop valve 2, pump II, stop valve 5 in sequence;

[0050] The outlet of the catalyst aqueous solution storage tank is connected to the inlet of the stop valve 9 after passing through the stop valve 3, pump III, stop valve 6 in sequence;

[0051] The nitrogen supply device is connected to the inlet of the stop valve 9 through the stop valve 10.

[0052] The outlet of the stop valve 9 is connected to the inlet of the pipeline reactor through a one-way valve, and a hydrogen inlet with a stop valve 7 is set on the pipeline between the one-way valve and the inlet of the pipeline reactor. The function of the one-way valve is to prevent the material from flowing back.

[0053] The outlet of the pipeline reactor is connected to the collection tank through a back pressure valve; the back pressure valve is used to control the reaction pressure of the pipeline reactor.

[0054] During actual operation, stop valves 1 to 9 are all in the open state, and pumps I to III are all in the working state; when the reaction is completed, all pumps are turned off, as well as stop valves 1 to 7, and stop valve 10 is opened to purge the material in the pipeline with nitrogen (after purging, close stop valve 10).

[0055] The n-octanal, ammonia and catalyst aqueous solutions are transported to the pipeline reactor by their respective pumps. The reaction liquid flowing out of the pipeline reactor flows into the collection tank through the back pressure valve, and then is extracted to remove the solvent and purified by reduced pressure distillation to obtain the product n-octylamine.

[0056] Example 1-1, a method for preparing n-octylamine, comprising the following steps:

[0057] The water-soluble homogeneous catalyst (catalyst solution) is composed of the following components in weight content: FeSO4 5wt%, EDTA-4Na 10wt%, HBF4 3wt%, and the rest is water.

[0058] The mass content of ammonia in ammonia water is 22-25%.

[0059] The inner diameter of the pipe reactor is about 10 mm and the pipe length is about 20 m.

[0060] Under the action of pump 1, n-octanal enters the pipeline reactor at a flow rate of 25g / min; under the action of pump 2, ammonia water enters the pipeline reactor at a flow rate of 15g / min; under the action of pump 3, the catalyst aqueous solution enters the pipeline reactor at a flow rate of 0.5g / min; the pumping rate from the hydrogen inlet to the pipeline reactor is 0.02m 3 / min (1.8g / min) of hydrogen.

[0061] The reaction materials formed by n-octanal, ammonia water and catalyst aqueous solution undergo amination reaction in a pipeline reactor at a reaction temperature of 80°C. The reaction residence time of the reaction materials in the pipeline reactor is 9.7 minutes. The pressure in the pipeline reactor is stabilized at 1.5 MPa by controlling the back pressure valve after the pipeline reactor.

[0062] Description: The amination reaction carried out in a pipeline reactor involves two steps of dehydration and hydrogenation. The dehydration is achieved by mixing n-octanal and ammonia water.

[0063] The resulting reaction liquid (a mixture consisting of an aqueous catalyst solution and an oil phase (including unreacted reactants and products)) flows into a collection tank, is extracted with ethyl acetate (the volume of ethyl acetate used is 0.5 to 2 times the volume of the reaction solution), and phases are separated. The ethyl acetate organic phase is collected, the solvent (ethyl acetate) is removed, and the product is purified by vacuum distillation (collecting the fraction at approximately 107.3° C. at 0.1 bar pressure) to obtain the n-octylamine product (purity ≥99.5%). The aqueous phase obtained by phase separation is the aqueous catalyst solution and can be reused.

[0064] When the amount of n-octanal m1 is 60g and the amount of ammonia m2 is about 36g, the amount of n-octylamine m3 obtained is 58g, and the yield is 96%. The formula for calculating the yield of n-octylamine is:

[0065]

[0066] In Examples 1-2 to 1-7, the product yield was tested by changing the reaction temperature in the pipeline reactor. The results are shown in Table 1 below.

[0067] Table 1. Effect of reaction temperature on n-octylamine yield

[0068]

[0069] The purity of the n-octylamine product obtained in the above case is ≥99.5%.

[0070] In the Example 2 series, relative to Example 1-1, the length of the pipeline reactor is changed, thereby correspondingly changing the residence time of the reaction, and the rest is the same as Example 1-1; thus, Examples 2-1 to 2-5 are obtained.

[0071] The product yield was detected and the following data were obtained (Table 2).

[0072] Table 2. Effect of reaction residence time on n-octylamine yield

[0073]

[0074] The purity of the n-octylamine product obtained in the above case is ≥99.5%.

[0075] In the Example 3 series, compared with the Example 1-1, the back pressure valve after the pipeline reactor is adjusted to change the reaction pressure, and the rest is the same as the Example 1-1, thereby obtaining the Examples 3-1 to 3-4.

[0076] The product yield was detected and the following data were obtained (Table 3).

[0077] Table 3. Effect of reaction pressure on n-octylamine yield

[0078]

[0079] The purity of the n-octylamine product obtained in the above case is ≥99.5%.

[0080] Example 4 series and Comparative Example 1 series,

[0081] Relative to Example 1-1, the flow rates of n-octanal, ammonia material, and catalyst aqueous solution were changed, and the tube length of the pipeline reactor was adjusted accordingly to ensure that the residence time of the reaction remained unchanged, and the rest was equivalent to Example 1-1; thereby obtaining corresponding Examples 4-1 to 4-4, and the product yield was tested to obtain the following data (Table 4).

[0082] Table 4. Effect of material flow rate ratio on n-octylamine yield

[0083]

[0084] Example 5 series,

[0085] Compared to Example 1-1, the flow rate of n-octanal remained unchanged, the ratio of hydrogen to aqueous ammonia was changed, and the length of the tubular reactor was adjusted accordingly to ensure that the residence time of the reaction remained unchanged. The remaining conditions were the same as in Example 1-1. Thus, corresponding Examples 5-1 to 5-5 were obtained, and the product yields were tested, yielding the following data (Table 5).

[0086] Table 5. Effect of material flow rate ratio on n-octylamine yield

[0087]

[0088] Example 6 Series: Compared to Example 1-1, the type of 3d metal salt, the type of EDTA-type ligand, and the type of promoter in the catalyst aqueous solution were changed, while the content remained unchanged. All other conditions were the same as in Example 1-1. The product yield was measured and the following data was obtained (Table 6).

[0089] Table 6. Effect of the composition of the catalyst aqueous solution on the yield of n-octylamine

[0090]

[0091] Example 7 series: Compared with Example 1-1, the contents of 3d metal salt and EDTA-type ligand in the catalyst aqueous solution were changed, and the rest were the same as Example 1-1. The product yield was tested and the following data were obtained (Table 7).

[0092] Table 7. Effect of the composition of the catalyst aqueous solution on the yield of n-octylamine

[0093]

[0094] Example 8 Series: Compared to Example 1-1, an alcohol solvent was added to promote the dissolution of the imine. The alcohol solvent and n-octanal were added together, with a weight ratio of 0.05:1. This formed solvent-containing n-octanal. The flow rate of the solvent-containing n-octanal was adjusted to ensure that the flow rate remained constant at 25 g / min. The length of the tubular reactor was slightly adjusted accordingly to ensure that the residence time of the reaction remained essentially unchanged. The remaining conditions were the same as in Example 1-1. Thus, corresponding Examples 8-1 to 8-3 were obtained. The product yields were tested, and the following data were obtained (Table 8).

[0095] Table 8. Effect of adding alcohol solvent on the yield of n-octylamine

[0096]

[0097]

[0098] Example 9 series, recycling and reuse

[0099] The aqueous phase (catalyst aqueous solution) collected in Example 1-1 was used to replace the catalyst aqueous solution, and the rest was the same as Example 1-1; thus, the recovery experiment was repeated, and this was the first recovery.

[0100] And so on, the second to fifth recycling are obtained accordingly.

[0101] The product yield was tested and the following data were obtained (Table 9). It can be seen that except for a small amount of catalyst loss due to extraction, the catalyst recovered five times can still maintain good reaction activity.

[0102] Table 9. Catalyst aqueous solution repeated recovery experiment

[0103]

[0104] Comparative Example 1: HBF4 as a promoter in the "catalyst aqueous solution" of Example 1-1 was omitted, and the amount of water was increased accordingly. The rest of the process was the same as in Example 1-1. The result was: the yield of n-octylamine was 55%.

[0105] Comparative Example 2: The catalyst in Example 1-1 was replaced with the heterogeneous catalyst Ni / NiO@C-700-200-2h-EtOH reported in the document Green Chem., 2020, 22, 7387, and mixed with ethanol to prepare a catalyst suspension feed. After the reaction, the yield of n-octylamine was only 40%, most of which was unreacted imine intermediates, and the catalytic activity of the catalyst recovered by filtration was 0.

[0106] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples and is subject to numerous variations. All variations that can be directly derived or conceived by a person of ordinary skill in the art from the disclosure of the present invention are considered to be within the scope of protection of the present invention.

Claims

1. A tubular method for producing n-octylamine, characterized in that: A water-soluble homogeneous catalyst is used to carry out an amination reaction in a pipeline reactor with n-octanal and ammonia as raw materials under a hydrogen atmosphere. The amination reaction includes a two-step series reaction of dehydration and hydrogenation. The following steps are involved: 1) Pumping n-octanal, ammonia water, and a water-soluble homogeneous catalyst into a pipeline reactor at a mass flow rate ratio of 1-3:1:0.01-0.1 to enter a dehydration and hydrogenation reaction; hydrogen is simultaneously pumped into the pipeline reactor at a mass flow rate ratio of hydrogen to ammonia water of 0.1-0.4:1; The reaction temperature of the pipeline reactor is 40-180° C., and the outlet back pressure valve of the pipeline reactor is controlled so that the reaction pressure of the pipeline reactor is 0.1-5 MPa and the reaction time is 5-20 min. The water-soluble homogeneous catalyst is composed of the following components in weight content: 0.5-10% of 3d metal salt, 5-30% of EDTA type ligand, 0.5-5% of promoter and water as the balance; The promoter is a protonic acid; The EDTA-type ligand is EDTA, EDTA-2Na, EDTA-4Na or CDTA; The 3d metal is any one of the sulfates or chlorides of Fe, Cu, and Zn; 2) The product obtained from the dehydration and hydrogenation reaction is post-treated to obtain crude n-octylamine.

2. The tubular method for producing n-octylamine according to claim 1, wherein: The protonic acid is any one of formic acid, acetic acid, CF3SO3H, and HBF4.

3. The tubular method for producing n-octylamine according to claim 2, wherein: 3d metal is ferrous sulfate or ferrous chloride; The protonic acid is HBF4.

4. The tubular method for producing n-octylamine according to claim 3, wherein: In step 1), an alcohol solvent is added to promote the dissolution of the substrate n-octanal in water. The alcohol solvent is at least one of methanol, ethanol, and isopropanol; Alcohol solvent: n-octanal = 0.01-0.2:1 by weight ratio.

5. A tubular method for synthesizing n-octylamine according to any one of claims 1 to 4, characterized in that: The post-treatment of step 2) is as follows: extracting the product obtained from the dehydration and hydrogenation reaction with ethyl acetate, separating the phases, and removing the solvent from the collected ethyl acetate layer containing the product to obtain crude n-octylamine.

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