Aldehyde removal method in amino alcohol preparation process

Abstract

The invention discloses a dealdehyding method in an amino alcohol preparation process, which comprises the following steps: S1, cleaning, drying and disinfecting a container; s2, adding 400-2000g of nitroalcohol with the concentration of 10-50% and a methanol solution into the container, and detecting the content of free formaldehyde; s3, primary amine, secondary amine and polyamine compounds are added into the container, and the container is heated to 50 DEG C and stirred for 1.0 h; s4, detecting the content of formaldehyde in the reaction liquid in the container by using a formaldehyde detector; s5, enabling the reaction liquid to pass through a trickle bed reactor filled with Raney nickel at a uniform speed, and detecting an outlet sample; and S6, analyzing the conversion rate of nitro alcohol and the selectivity of amino alcohol according to a gas phase detection result, and transferring the obtained hydrogenation reaction liquid to a desolventizing tower to recover the solvent methanol, the dealdehyding agent is low in price and small in usage amount, and does not affect solvent recycling.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of de-aldehyde method, and in particular to a de-aldehyde method in the preparation process of amino alcohol. BACKGROUND

[0002] Nitroalkane and formaldehyde are condensed to prepare nitro alcohol, and the nitro alcohol can be reduced to prepare a series of amino alcohols. Amino alcohol is an important organic synthesis raw material and is widely used in coatings, metal processing, electronics, new energy, cosmetics, medicine and pesticide, carbon dioxide absorption and other fields. For example, 2-amino-2-methyl-1-propanol (AMP) is mainly used for high-end water-based coating additives, which can improve the dispersion efficiency of pigments, stabilize the pH value, and significantly reduce the odor of the coating; as a cutting fluid formula raw material for processing precision parts, it can improve the metal processing precision and prolong the service life of the metal processing fluid; in the field of cosmetics, it can be applied to relatively high-end styling sprays and jelly water, and AMP is also a very effective CO2 chemical ion exchange resin. Other amino alcohol products mainly include 2-amino-2-methyl-1-propanol (AMP), 2-aminobutanol (AB), 2-amino-2-ethyl-1, 3-propanediol (AEPD), 2-amino-2-methyl-1, 3-propanediol (AMPD), etc. In order to ensure the conversion rate of nitro alcohol raw material in the condensation polymerization reaction of nitroalkane and formaldehyde under the action of alkaline catalyst, the amount of formaldehyde raw material is increased, so that there is a large amount of unreacted formaldehyde in the reaction solution. The residual formaldehyde will reduce the selectivity of the main product amino alcohol in the hydrogenation reaction process. In patent CN114105788 A, primary amine organic amines such as isopropylamine, isobutylamine, and ethanolamine are added to the reaction solution. In patent CN102803201 A, C1-C6 alkylamine (ethylamine, propylamine, or butylamine) or C1-C6 nitroalkane (nitroethane, nitropropane, etc.) is added in the preparation process of amino alcohol.

[0003] In the above two processes, the de-formaldehyde scheme is to introduce an aldehyde scavenger such as an amine substance or a nitroalkane in the hydrogenation process. Formaldehyde and the aldehyde scavenger react to generate a substance that does not affect the purity of the amino alcohol (2-amino-2-methyl-1-propanol) product in the hydrogenation process.

[0004] N-methyl isopropylamine (boiling point 50-53℃) or N,N-dimethyl isopropylamine (boiling point 65℃) are obtained by isopropylamine and formaldehyde nucleophilic addition, dehydration and hydrogenation reduction reaction; aminoethane is synthesized by hydrogenation of nitroethane, and then N,N-dimethylethylamine (boiling point 36-38℃) or N-methylethylamine (boiling point 36-37℃) is synthesized by hydroxymethylation reaction with formaldehyde, both of which have boiling points below 100℃; propylamine is synthesized by hydrogenation of nitropropane, and then N,N-dimethylpropylamine (boiling point 65.85℃) and N-methyl-n-propylamine (boiling point 65℃) are obtained by further addition of formaldehyde to propylamine, both of which have boiling points below 70℃. During the product separation process, these heteroamine substances will continue to be entrained in the solvent, directly affecting the yield and quality of the amino alcohol product, and must be further treated before reuse, increasing the production cost.

[0005] Patent CN108976128A discloses a process for converting formaldehyde into methylal and removing it from the system by reactive distillation, which can reduce the formaldehyde content to 5-200ppm. Because the reactive distillation process uses an acidic catalyst, the condensation process of nitroalcohol (NMP) uses an alkaline catalyst, and the de-aldehyde process consumes a large amount of acidic catalyst, not only increasing the amount of solid waste, but also increasing the production cost. SUMMARY

[0006] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a de-aldehyde method in the preparation process of amino alcohol, which uses high-boiling primary amine, secondary amine and polyamine compounds as de-aldehyde agent. The substance obtained by the reaction of the de-aldehyde agent and formaldehyde has a high boiling point (>250℃) and stable properties during the separation process of the target product, which does not affect the product quality and solvent reuse. The recovered solvent can be directly reused. The de-aldehyde process is simple. The de-aldehyde agent is cheap and has a small usage amount, which can reduce the production cost.

[0007] According to the technical scheme provided by the embodiment of the present application, a de-aldehyde method in an amino alcohol preparation process comprises the following steps: S1, cleaning, drying and sterilizing a container; S2, taking 400-2000g of a nitro alcohol and methanol solution with a concentration of 10-50% and adding the solution into the container, and detecting the free formaldehyde content; S3, adding primary amine, secondary amine and polyamine compounds into the container, heating the container to 50 DEG C and stirring for 1.0h; S4, detecting the formaldehyde content of the reaction liquid in the container by using a formaldehyde detector; S5, uniformly passing the reaction liquid through a trickle bed reactor provided with Raney nickel, and detecting the outlet sample; S6, analyzing the nitro alcohol conversion rate and amino alcohol selectivity according to the gas phase detection result, and the rest is an incomplete intermediate in the hydrogenation reaction, and the obtained hydrogenation reaction liquid is transferred to a desolventizing column to recover the solvent methanol; and S7, detecting the chromatographic purity, amine impurity and PH value of the recovered solvent methanol. The primary amine, secondary amine and polyamine compounds are one of diethanolamine, N-n-butyl ethylenediamine, N-(2-hydroxyethyl) diethylene triamine and hydroxyethyl ethylenediamine. The container is cleaned by using clean water, the container is dried by using a dryer, and the sterilization time of the container is 10-30min. The container is made of high-temperature resistant material, the detection time of the formaldehyde detector is less than 5min. The container is stirred by using a paddle stirring device, and the stirring time is 3-6min. The container is heated by using an electric heating plate, and the desolventizing column is a vertical desolventizing column. The addition amount of the primary amine, secondary amine and polyamine substance is 0.001%-5% of the free formaldehyde amount, and preferably 0.005%-0.1%.

[0008] In summary, the process uses high-boiling primary amine, secondary amine and polyamine compounds as de-aldehyde agents, the raw materials are easy to obtain, the price is low, the boiling point is high (> 250 DEG C), the properties are stable in the target product separation process, the product quality and solvent reuse are not affected, the recovered solvent can be directly reused, the de-aldehyde process is simple, the de-aldehyde agent is cheap, the use amount is small, and the production cost can be reduced. DETAILED DESCRIPTION

[0009] The present application will be further described in conjunction with the embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application.

[0010] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail in conjunction with the embodiments.

[0011] The reaction products NMP, AMP, MMAMP, DMAMP, AEPD, propylamine, N-methyl propylamine, isopropylamine, and methyl isopropylamine, etc. are analyzed by a gas chromatograph (Agilent 7890A), and the chromatographic column is DB 624. The formaldehyde content is determined by the acetylacetone spectrophotometric method (determined by a UV-visible spectrometer (Shimadzu UV 2550), and the determination wavelength is 413 nm.

[0012] A de-aldehyde method in an amino alcohol preparation process, comprising the following steps: S1, cleaning, drying and sterilizing a container; S2, taking 400-2000g of a nitro alcohol and methanol solution with a concentration of 10-50% and detecting free formaldehyde content; S3, adding primary amine, secondary amine and polyamine compounds to the container, heating the container to 50°C and stirring for 1.0h; S4, detecting the formaldehyde content of the reaction liquid in the container by using a formaldehyde detector; S5, passing the reaction liquid through a trickle bed reactor with Raney nickel at a constant speed and detecting the outlet sample; S6, analyzing the conversion rate of nitro alcohol and the selectivity of amino alcohol according to the gas phase detection result, and the rest is an incomplete intermediate of hydrogenation reaction, and the obtained hydrogenation reaction liquid is transferred to a desolventizing column to recover solvent methanol; S7, analyzing the chromatographic purity, amine impurities and PH value of the recovered solvent methanol. The primary amine, secondary amine and polyamine compounds are one of diethanolamine, N-n-butyl ethylenediamine, N-(2-hydroxyethyl) diethylene triamine and hydroxyethyl ethylenediamine. The container is cleaned with water, the container is dried by a dryer, and the sterilization time of the container is 10-30min. The container is made of high-temperature resistant material, and the detection time of the formaldehyde detector is within 5min. The container is stirred by a paddle stirring device, and the stirring time is 3-6min. The container is heated by an electric heating plate, and the desolventizing column is a vertical desolventizing column. The addition amount of the primary amine, secondary amine and polyamine substance is 0.001%-5% of the free formaldehyde content, and is preferably 0.005%-0.1%.

[0013] Example 1: A container is cleaned, dried and sterilized; 2000g of a 2-nitro-2-methyl-1-propanol (NMP) and methanol solution with a concentration of 10-20% is taken and added to the container, and the free formaldehyde content is detected as 4000ppm; 8g of diethylene triamine is added to the container, the container is heated to 50°C and stirred for 1.0h; the formaldehyde content of the reaction liquid in the container is detected by using a formaldehyde detector as 20ppm; the reaction liquid is passed through a trickle bed reactor with Raney nickel at a constant speed, and the outlet sample is detected; according to the gas phase detection result, the conversion rate of NMP is 99.9%, the selectivity of AMP is 99.4%, and the rest is an incomplete intermediate of hydrogenation reaction, and the obtained hydrogenation reaction liquid is transferred to a desolventizing column to recover solvent methanol; the chromatographic purity of the recovered methanol is 99.75%, isopropylamine / methyl isopropylamine is 0.0056%, and the PH value is 8.05.

[0014] Example 2: The container was cleaned, dried and sterilized; 2-nitro-2-methyl-1-propanol (NMP) and methanol solution with a concentration of 10-20% 2000g was added into the container, and the free formaldehyde content was detected to be 6120ppm; diethylenetriamine 8g was added into the container, the container was heated to 50°C and stirred for 1.0h; the formaldehyde content of the reaction liquid in the container was detected by using a formaldehyde detector to be 15ppm; the reaction liquid was uniformly passed through the trickle bed reactor with Raney nickel, and the outlet sample was detected; according to the gas phase detection result, the NMP conversion rate was 99.9%, the AMP selectivity was 99.4%, and the rest was incomplete intermediate of hydrogenation reaction. The obtained hydrogenation reaction liquid was transferred to the desolventizing recovery tank to recover the solvent methanol; the recovered methanol had a chromatographic purity of 99.83%, isopropylamine / methyl isopropylamine 0.005%, and PH 7.9.

[0015] Example 3: 2-nitro-2-methyl-1-propanol (NMP) reaction liquid with a concentration of 50% 400g was added into the recovered methanol 1600g (the free formaldehyde content was detected to be 4800ppm) in Example 2, diethanolamine 7g was added, stirred at 50°C for 1.0h, and the formaldehyde content was detected to be 20ppm. The reaction liquid was uniformly passed through the trickle bed reactor with Raney nickel, the outlet sample was detected, and according to the gas phase detection result, the NMP conversion rate was 99.9%, the AMP selectivity was 99.5%, and the rest was incomplete intermediate of hydrogenation reaction.

[0016] Example 4: The container was cleaned, dried and sterilized; 2-nitrobutanol and methanol solution with a concentration of 10-15% 2000g was added into the container, and the free formaldehyde content was detected to be 3120ppm; diethylenetriamine 4.5g was added into the container, the container was heated to 50°C and stirred for 1.0h; the formaldehyde content of the reaction liquid in the container was detected by using a formaldehyde detector to be 18ppm; the reaction liquid was uniformly passed through the trickle bed reactor with Raney nickel, and the outlet sample was detected; according to the gas phase detection result, the 2-nitrobutanol conversion rate was 99.9%, the 2-aminobutanol selectivity was 99.4%, and the rest was incomplete intermediate of hydrogenation reaction. The obtained hydrogenation reaction liquid was transferred to the desolventizing recovery tank to recover the solvent methanol; the recovered methanol had a chromatographic purity of 99.85%, propylamine / N-methylpropylamine 0.004%, and PH 7.9.

[0017] The obtained recovered methanol 2000 g was added with 15% 2-nitrobutanol, and after stirring uniformly, the free formaldehyde content was detected as 2780 ppm, 3.5 g of diethylene triamine was added, the container was heated to 50 DEG C and stirred for 1.0 h; the formaldehyde content of the reaction liquid in the container was detected by using a formaldehyde detector as 15 ppm; the reaction liquid was uniformly passed through a trickle bed reactor provided with Raney nickel, and the outlet sample was detected; according to the gas phase detection result, the conversion rate of 2-nitrobutanol was 99.92%, the selectivity of 2-aminobutanol was 99.42%, and the rest was incomplete intermediate of hydrogenation reaction.

[0018] Example 1: 2000 g of 2-nitro-2-methyl-1-propanol (NMP) methanol solution with a concentration of 10-20% (the free formaldehyde content was detected as 4000 ppm) was taken, 15 g of isopropylamine was added, stirred at 50 DEG C for 1.0 h, the formaldehyde content in the reaction liquid was detected as 20 ppm, the reaction liquid was uniformly passed through a trickle bed reactor provided with Raney nickel, the outlet sample was detected, and according to the gas phase detection result, the conversion rate of NMP was 99.9%, the selectivity of AMP was 99.4%, the recovered methanol was recovered from the obtained hydrogenation reaction, the chromatographic purity of the recovered methanol was 98.3%, the methyl isopropylamine was 0.6%, the isopropylamine was 0.7%, the rest was small molecule heteroamine, and the recovered methanol PH was 11.5.

[0019] Example 2: 400 g of 2-nitro-2-methyl-1-propanol (NMP) reaction liquid with a concentration of 10-20% was taken, 1600 g of recovered methanol in the comparative example (the free formaldehyde content was detected as 5000 ppm) was added, 7 g of isopropylamine was added, stirred at 50 DEG C for 1.0 h, the formaldehyde content was detected as 20 ppm, the reaction liquid was uniformly passed through a trickle bed reactor provided with Raney nickel, the outlet sample was detected, and according to the gas phase detection result, the conversion rate of NMP was 99.9%, the selectivity of AMP was 90.4%, MAMP was 3.2%, DMAMP was 0.8%, isopropylamine was 4%, methyl isopropylamine was 2.1%, and the rest was incomplete intermediate of hydrogenation reaction.

[0020] The above description is only the preferred embodiment of the present application and the description of the technical principle and the like scheme. Meanwhile, the invention range involved in the present application is not limited to the technical scheme formed by the specific combination of the above technical features, and should also cover other technical schemes formed by any combination of the above technical features or equivalent features without departing from the invention concept. For example, the technical scheme formed by replacing the above features with the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A dealdehyde method in an amino alcohol preparation process, characterized in that: Including the following step, S1. Clean, dry and sterilize the container; S2, adding 400-2000 g of a 10-50% nitroalcohol and methanol solution into the container, and detecting the free formaldehyde content; S3. Add primary amine, secondary amine and polyamine compound into the container, heat the container to 50° C. and stir for 1.0 h; S4, using a formaldehyde detector to detect the formaldehyde content of the reaction liquid in the container; S5, passing the reaction solution through a trickle bed reactor containing Raney nickel at a uniform rate, and detecting an outlet sample; S6. Analyze the nitroalcohol conversion and aminoalcohol selectivity based on the gas phase detection results. The rest are incomplete intermediates of the hydrogenation reaction. Transfer the resulting hydrogenation reaction liquid to a desolventizing tower to recover the solvent methanol. S7, performing chromatographic purity, amine impurity analysis and pH value detection on the recovered solvent methanol.

2. The method for removing aldehydes from an amino alcohol preparation process according to claim 1, wherein: The primary amine, secondary amine and polyamine compound is one of diethanolamine, N-n-butylethylenediamine, N-(2-hydroxyethyl)diethylenetriamine and hydroxyethylethylenediamine.

3. The dealdehyde removal method in a process for preparing amino alcohols according to claim 1, wherein: The container is cleaned with clean water and dried in a dryer. The disinfection time of the container is 10 to 30 minutes.

4. The method for removing aldehydes from an amino alcohol preparation process according to claim 1, wherein: The container is made of high-temperature resistant material, and the detection time of the formaldehyde detector is within 5 minutes.

5. The method for removing aldehydes from an amino alcohol preparation process according to claim 1, wherein: The container is stirred by a paddle stirring device, and the stirring time is 3 to 6 minutes.

6. The method for removing aldehydes from an amino alcohol preparation process according to claim 1, wherein: The container is heated by an electric heating plate, and the desolventizing tower is a vertical desolventizing tower.

7. The method for removing aldehydes from an amino alcohol preparation process according to claim 1, wherein: The added amount of the primary amine, secondary amine and polyamine substances is 0.001% to 5% of the free formaldehyde amount, preferably 0.005% to 0.1%.