A method for preparing isooctylamine by a two-step process using isooctanol

Abstract

This invention relates to the synthesis of isooctylamine, providing a two-step method for preparing isooctylamine using isooctyl alcohol, comprising the preparation of a fixed-bed catalyst A, the preparation of isooctonitrile, and the preparation of isooctylamine. Fixed-bed catalyst A uses γ-Al₂O₃ as a support, converting copper nitrate and other substances into oxide forms, which are then reduced by hydrogen gas to form the catalyst. In this invention, isooctyl alcohol is used as a raw material in a fixed-bed reactor. Isooctyl alcohol and ammonia undergo dehydrogenation to produce isooctonitrile, which is then hydrogenated to obtain isooctylamine. During the nitrile preparation stage, the isooctonitrile content is greater than 99%, and the residual alcohol is less than 0.5%. After hydrodistillation and alkali treatment to remove isooctamide, the isooctylamine content is greater than 99.0%, resulting in high product yield and high purity.

Description

Technical Field

[0001] This invention relates to the field of isooctylamine synthesis, and in particular to a two-step method for preparing isooctylamine using isooctyl alcohol as a raw material. Background Technology

[0002] Isooctylamine (2-ethylhexylamine), as an organic fatty amine, has a wide range of applications. It is a major raw material for synthesizing pesticide synergists, and also serves as an intermediate in the synthesis of dyes, pigments, surfactants, and insecticides, as well as a raw material for the production of stabilizers, preservatives, antioxidants, flotation agents, and emulsifiers. Its main synthetic routes involve reacting isooctanoic acid with ammonia at high temperatures (280-320℃) to prepare isooctonitrile, followed by hydrogenation. This method, however, isooctanoic acid is highly corrosive to equipment at high temperatures, requiring high precision. Another method involves the ammoniation of isooctaldehyde under palladium-based noble metal catalysts. This method requires expensive palladium catalysts, and isooctaldehyde is a scarce raw material, hindering industrialization. Another common synthetic method is the direct ammoniation of isooctyl alcohol, as disclosed in invention patent CN200310122670, which describes a method for synthesizing isooctylamine from isools. However, this method suffers from low conversion rates, numerous impurities, and low yields. Summary of the Invention

[0003] To improve the yield and purity of isooctanol products and reduce equipment corrosion, this invention provides a two-step method for preparing isooctylamine using isooctanol as a raw material.

[0004] The technical solution adopted in this invention is as follows: A method for preparing isooctylamine using isooctyl alcohol in two steps, characterized by comprising the following steps: Step 1: Prepare fixed-bed catalyst A, load the catalyst into a fixed-bed reactor, introduce hydrogen and reduce the catalyst by programmed temperature increase, and after the reduction is completed, lower the fixed-bed temperature to the reaction temperature; Step 2: Set the temperature of the preheater and fixed bed between 260-270℃, introduce ammonia to replace the hydrogen in the fixed bed system for 60-90 minutes. After replacement, control the ammonia flow rate at 200-300 ml / min. Maintain the fixed bed pressure at 0.05-0.1 MPa through the back pressure valve, and pump isooctyl alcohol into the preheater. After the isooctyl alcohol and ammonia are preheated by the preheater, they enter the fixed bed for reaction. The reaction ends when the isooctonitrile content is greater than 99% and the residual alcohol is less than 0.5%. The semi-finished product in the fixed bed reactor is condensed by the condenser and then enters the receiving tank. Step 3: After the semi-finished product from Step 2 is separated into oil and water in the receiving tank, the upper layer of isooctonitrile is added to the reaction vessel, along with catalyst B and inhibitor. A hydrogenation reaction is then introduced. After the reaction is completed, the mixture is filtered and transferred to a distillation vessel. In the distillation vessel, 1-1.5% sodium hydroxide (based on the total amine content) is added. The mixture is then bubbled with nitrogen at 130-150℃ for 5-8 hours. After sampling and analysis, the isooctamide content is found to be less than 0.1%. The mixture is then cooled and distilled to obtain isooctamide with a content greater than 99%.

[0005] Furthermore, the preparation method of catalyst A includes the following steps: S1: In a reaction vessel, a measured amount of copper nitrate (Cu(NO3)2·3H2O), chromium nitrate (Cr(NO3)3·9H2O), manganese nitrate (Mn(NO3)2·4H2O), and zinc nitrate (Zn(NO3)2·6H2O) are completely dissolved in deionized water, and sodium carbonate is added to adjust the pH to 7-8. S2: Add γ-Al2O3, stir at 50-60℃ for 3-5 hours, wash with water three times, remove water by centrifuge, add graphite to filter cake and stir evenly, and extrude into cylindrical bodies with a length of 3-5mm and a diameter of 1-2mm for later use. S3: Place the cylindrical body from S2 into a muffle furnace and use a programmed heating method: raise the temperature from room temperature to 250°C at a rate of 5°C / min and hold for 2 hours; then raise the temperature to 450°C at a rate of 3°C / min and hold for 4 hours to convert the active components into oxide form. After calcination, allow it to cool naturally to room temperature.

[0006] The oxides in step S3 are in the following weight ratios: copper oxide 10-15%, chromium oxide 5-10%, manganese oxide 0.1-1%, zinc oxide 1-5%, and the balance is γ-Al2O3 support.

[0007] Among them, γ-Al2O3 has a particle size of 2-5 mm and a specific surface area of ​​150-200 m² / g.

[0008] Furthermore, in step 1, the flow rate of hydrogen gas is controlled at 200-500 mL / min, and the temperature program is to increase to 200℃ at 2℃ / min, hold for 1 h, and then increase to 300℃ at 1℃ / min and hold for 3 h.

[0009] Furthermore, in step 1, the flow rate of isooctanol pumped in is 0.8-1.5 ml / min, and the ammonia flow rate is 200-300 ml / min.

[0010] Furthermore, the hydrogenation reaction in step 3 is carried out at a temperature of 80-120℃, a reaction pressure of 2-3MPa, and a reaction time of 3-5h.

[0011] Furthermore, catalyst B in step 3 is a Raney nickel catalyst.

[0012] This invention uses isooctanol as a raw material in a fixed-bed reactor. Isooctanol and ammonia are dehydrogenated to produce isooctonitrile, which is then hydrogenated to produce isooctylamine. During the nitrile production stage, the isooctonitrile content is greater than 99%, and the residual alcohol is less than 0.5%. After hydrogenation distillation and alkali treatment to remove isooctamide, the isooctylamine content is greater than 99.0%, resulting in high product yield and high purity. Detailed Implementation

[0013] The specific embodiments of the present invention will be further described in detail below.

[0014] Preparation Example 1: Preparation of Catalyst A S1: In a reaction vessel, a fixed amount of copper nitrate (Cu(NO3)2·3H2O), chromium nitrate (Cr(NO3)3·9H2O), manganese nitrate (Mn(NO3)2·4H2O), and zinc nitrate (Zn(NO3)2·6H2O) are completely dissolved in deionized water, and sodium carbonate is added to adjust the pH to 7-8, in which the metal ions form carbonate precipitates.

[0015] S2: Add γ-Al2O3 support to the reactor. The particle size of γ-Al2O3 is 2-5 mm and the specific surface area is 150-200 m² / g. Stir at 50-60℃ for 3-5 h to allow the support to fully contact and adhere to the metal ion precipitate. Remove impurities from the precipitate by washing it three times with water. Then remove the water by centrifugation to obtain the separated filter cake.

[0016] Add graphite to the filter cake and stir evenly. Graphite, as a stable binder, does not participate in the reaction and is used for the extrusion molding of the catalyst. Extrude cylindrical bodies with a length of 3-5 mm and a diameter of 1-2 mm using an extruder for later use. S3: The cylindrical body from S2 is placed in a muffle furnace and heated using a programmed temperature rise method: from room temperature to 250℃ at a rate of 5℃ / min, held for 2 hours; then increased to 450℃ at a rate of 3℃ / min, held for 4 hours, to convert the active components into oxide form. After calcination, it is naturally cooled to room temperature. The final oxide contains 10-15% copper oxide, 5-10% chromium oxide, 0.1-1% manganese oxide, 1-5% zinc oxide, and the balance is γ-Al2O3 support.

[0017] The calcined oxide was loaded into a fixed-bed reactor, and hydrogen was introduced at a flow rate of 200-500 mL / min. The temperature was programmed for reduction: the temperature was increased to 200℃ at 2℃ / min and held for 1 h; then increased to 300℃ at 1℃ / min and held for 3 h. After the reduction was completed, the oxide reduction was finished and catalyst A was obtained. The fixed-bed temperature was then reduced to a suitable reaction temperature.

[0018] Preparation Example 2: Preparation of Isooctylamine Step 1: Preparation of isooctonitrile Set the preheater and fixed bed temperatures between 260-270℃. Open the ammonia gas supply, controlling the flow rate at 300-500 ml / min. Open the vent to replace the hydrogen in the fixed bed system for 60-90 minutes. After replacement, control the ammonia flow rate at 200-300 ml / min. Maintain the fixed bed pressure at 0.05-0.1 MPa using the back pressure valve. Begin pumping in isooctanol at a flow rate of 0.8-1.5 ml / min. After preheating in the preheater, the isooctanol and ammonia enter the fixed bed for reaction. The isooctonitrile content should be greater than 99%, and the residual alcohol less than 0.5%. After the reaction, the mixture is condensed in the condenser and then transferred to the receiving tank.

[0019] Step 2: Preparation of isooctylamine The dehydrated isooctanonitrile is added to a reaction vessel, along with a Raney nickel catalyst and an inhibitor. The reaction temperature is controlled at 80-120℃, the reaction pressure at 2-3 MPa, and the reaction time at 3-5 hours. After hydrogenation and sedimentation, the mixture is filtered and transferred to a distillation vessel. In the distillation vessel, 1-1.5% sodium hydroxide (based on the total amine content) is added, and the mixture is bubbled with nitrogen gas at 130-150℃ for 5-8 hours. After sampling and analysis, the isooctanoamide content is found to be less than 0.1%. Then, the mixture is cooled and distilled to obtain isooctanoamide with a purity greater than 99%. Example

[0020] The catalyst was prepared according to the following composition: copper content 15%, chromium content 8%, manganese content 0.5%, and zinc content 3%. Fixed-bed catalyst A was prepared according to the catalyst preparation process.

[0021] 500g of catalyst A was loaded into a fixed-bed reactor. After reducing the catalyst according to the catalyst reduction method, the temperature was lowered to 260℃, and the ammonia flow rate was adjusted to 300ml / min. The fixed bed was purged for 60min. After the purging was completed, the fixed bed pressure was adjusted to 0.1MPa through the back pressure valve. The isooctyl alcohol was pumped in at a rate of 1.5ml / min, and ammonia was simultaneously introduced into the fixed bed at a rate of 300ml / min. The generated isooctonitrile was condensed and entered into the product collection tank. After continuous pumping for 48 hours, samples were taken for analysis. The chromatographic content of isooctonitrile was 99.1%, the content of isooctyl alcohol was 0.1%, and the content of isooctamide was 0.5%.

[0022] Add 400g of isooctonitrile after water separation to the reactor, add 20g of Raney nickel, add 4g of 48% sodium hydroxide, purge with nitrogen three times, purge with hydrogen three times, raise the temperature to 80℃, and set the reaction pressure to 2MPa. After 5 hours of reaction, the residual isooctonitrile was found to be 0.05%, and the reaction was terminated. After filtration, the mixture was transferred to a distillation reactor.

[0023] During the distillation process, 1% sodium hydroxide of the total amine content was added and the temperature was raised to 140°C. The reaction was carried out under nitrogen bubbling for 5 hours. The isooctamide content was measured to be 0.06%. The temperature was then lowered and the mixture was slowly vacuumed for distillation to obtain an isooctamide content of 99.1%. Example

[0024] The catalyst was prepared according to the following composition: copper content 10%, chromium content 5%, manganese content 0.1%, and zinc content 1%. Fixed-bed catalyst A was prepared according to the catalyst preparation process. 500g of catalyst A was loaded into a fixed-bed reactor. After reducing the catalyst according to the catalyst reduction method, the temperature was lowered to 270℃, and the ammonia flow rate was adjusted to 200ml / min. The fixed bed was purged for 90min. After the purging was completed, the fixed bed pressure was adjusted to 0.08MPa through the back pressure valve. The isooctanol pumping rate was 0.8ml / min, and ammonia was simultaneously introduced into the fixed bed at a rate of 200ml / min. The generated isooctonitrile was condensed and entered into the product collection tank. After continuous pumping for 48 hours, samples were taken for analysis. The chromatographic content of isooctonitrile was 99.0%, the content of isooctol was 0.08%, and the content of isooctamide was 0.6%.

[0025] Add 400g of isooctonitrile after water separation to the reactor, add 25g of Raney nickel, add 4g of 48% sodium hydroxide, purge with nitrogen three times, purge with hydrogen three times, raise the temperature to 100℃, and set the reaction pressure to 3MPa. After 3 hours of reaction, the residual isooctonitrile was found to be 0.06%. The reaction was then stopped, filtered, and distilled.

[0026] During the distillation process, sodium hydroxide of 1.5% of the total amine content was added and the temperature was raised to 130°C. The reaction was carried out under nitrogen bubbling for 8 hours. The content of isooctamide was measured to be 0.08%. Then, the temperature was lowered and the mixture was slowly vacuumed for distillation to obtain isooctamide with a content of 99.3%. Example

[0027] The catalyst was prepared according to the following composition: copper content 12%, chromium content 3%, manganese content 1%, zinc content 2%. Fixed-bed catalyst A was prepared according to the catalyst preparation process. 500g of catalyst A was loaded into a fixed-bed reactor. After reducing the catalyst according to the catalyst reduction method, the temperature was lowered to 265℃, and the ammonia flow rate was adjusted to 250ml / min. The fixed bed was purged for 80min. After the purging was completed, the fixed bed pressure was adjusted to 0.09MPa through the back pressure valve. The isooctyl alcohol was pumped in at a rate of 1ml / min, and ammonia was simultaneously introduced into the fixed bed at a rate of 250ml / min. The generated isooctonitrile was condensed and entered into the product collection tank. After continuous pumping for 48 hours, samples were taken for analysis. The chromatographic content of isooctonitrile was 99.1%, the content of isooctyl alcohol was 0.09%, and the content of isooctamide was 0.4%.

[0028] Add 400g of isooctonitrile after water separation to the reactor, add 30g of Raney nickel, add 4g of 48% sodium hydroxide, purge with nitrogen three times, purge with hydrogen three times, then raise the temperature to 120℃, the reaction pressure to 2.5MPa, and after 4 hours of reaction, the residual isooctonitrile was found to be 0.04%, the reaction was stopped, and the mixture was filtered and then distilled.

[0029] During the distillation process, sodium hydroxide of 1.2% of the total amine content was added and the temperature was raised to 140°C. After 6 hours of nitrogen bubbling reaction, the isooctamide content was found to be 0.07%. Then, the temperature was lowered and the sample was slowly vacuumed for distillation to obtain isooctamide with a content of 99.6%.

[0030] As can be seen from the results of the above embodiments, the isooctylamine preparation method provided by the present invention uses isooctyl alcohol as raw material to prepare isooctylamine through a two-step reaction. The preparation process has low equipment corrosion, the catalyst used does not require expensive precious metal raw materials, the preparation cost is lower, and the purity of the obtained isooctylamine product can reach more than 99%, with low impurity content and higher yield, making it suitable for large-scale industrial production.

Claims

1. A method for preparing isooctylamine using a two-step process with isooctyl alcohol, characterized in that, Includes the following steps: Step 1: Prepare fixed-bed catalyst A, load the catalyst into a fixed-bed reactor, introduce hydrogen and reduce the catalyst by programmed temperature increase, and after the reduction is completed, lower the fixed-bed temperature to the reaction temperature; Step 2: Set the temperature of the preheater and fixed bed between 260-270℃, introduce ammonia to replace the hydrogen in the fixed bed system for 60-90 minutes. After replacement, control the ammonia flow rate at 200-300 ml / min. Maintain the fixed bed pressure at 0.05-0.1 MPa through the back pressure valve, and pump isooctyl alcohol into the preheater. After the isooctyl alcohol and ammonia are preheated by the preheater, they enter the fixed bed for reaction. The reaction ends when the isooctonitrile content is greater than 99% and the residual alcohol is less than 0.5%. The semi-finished product in the fixed bed reactor is condensed by the condenser and then enters the receiving tank. Step 3: After the semi-finished product from Step 2 is separated into oil and water in the receiving tank, the upper layer of isooctonitrile is added to the reaction vessel, along with catalyst B and inhibitor. A hydrogenation reaction is then introduced. After the reaction is completed, the mixture is filtered and transferred to a distillation vessel. In the distillation vessel, 1-1.5% sodium hydroxide (based on the total amine content) is added. The mixture is then bubbled with nitrogen at 130-150℃ for 5-8 hours. After sampling and analysis, the isooctamide content is found to be less than 0.1%. The mixture is then cooled and distilled to obtain isooctamide with a content greater than 99%.

2. The method for preparing isooctylamine using a two-step method with isooctyl alcohol according to claim 1, characterized in that, The preparation method of catalyst A includes the following steps: S1: In a reaction vessel, a measured amount of copper nitrate (Cu(NO3)2·3H2O), chromium nitrate (Cr(NO3)3·9H2O), manganese nitrate (Mn(NO3)2·4H2O), and zinc nitrate (Zn(NO3)2·6H2O) are completely dissolved in deionized water, and sodium carbonate is added to adjust the pH to 7-8. S2: Add γ-Al2O3, stir at 50-60℃ for 3-5 hours, wash with water three times, remove water through centrifuge to obtain filter cake, add graphite to filter cake and stir evenly, and extrude into cylindrical bodies with a length of 3-5mm and a diameter of 1-2mm for later use. S3: Place the cylindrical body from S2 into a muffle furnace and use a programmed heating method: raise the temperature from room temperature to 250°C at a rate of 5°C / min and hold for 2 hours; then raise the temperature to 450°C at a rate of 3°C / min and hold for 4 hours to convert the active components into oxide form. After calcination, allow it to cool naturally to room temperature.

3. The method for preparing isooctylamine using a two-step method with isooctyl alcohol according to claim 2, characterized in that, The oxides in step S3 are in the following weight ratios: copper oxide 10-15%, chromium oxide 5-10%, manganese oxide 0.1-1%, zinc oxide 1-5%, aluminum oxide 50-60%, and the balance is graphite.

4. The method for preparing isooctylamine using a two-step method with isooctyl alcohol according to claim 1, characterized in that, In step 1, the flow rate of hydrogen gas is controlled at 200-500 mL / min. The temperature program is to increase the temperature to 200℃ at 2℃ / min, hold for 1 hour, and then increase the temperature to 300℃ at 1℃ / min and hold for 3 hours.

5. The method for preparing isooctylamine using a two-step method with isooctyl alcohol according to claim 1, characterized in that, In step 1, the flow rate of isooctanol pumped in is 0.8-1.5 ml / min, and the ammonia flow rate is 200-300 ml / min.

6. The method for preparing isooctylamine using a two-step method with isooctyl alcohol according to claim 1, characterized in that, The hydrogenation reaction in step 3 is carried out at a temperature of 80-120℃, a pressure of 2-3 MPa, and for 3-5 hours.

7. The method for preparing isooctylamine using a two-step method with isooctyl alcohol according to claim 1, characterized in that, In step 3, catalyst B is a Raney nickel catalyst.