Method for recycling aniline in preparation process of diphenylmethane series diamine and polyamine

Abstract

The invention relates to a method for recycling aniline in a preparation process of diphenylmethane series diamine and polyamine. The method is used for recycling aniline from an aniline-water mixed solution generated in a DAM refining process through liquid-liquid two-phase standing layering, wherein particularly the aniline content of 53 wt% in the aniline-water mixed solution is taken as a boundary value, when the aniline content is less than 53 wt%, the aniline-water mixed solution is directly layered, and when the aniline content is more than or equal to 53 wt%, the aniline content in theaniline-water mixed solution is adjusted to be less than 53 wt% and then layering is performed, or an auxiliary aid is added into the aniline-water mixed solution and then layering is performed, wherein the auxiliary aid is one or more of water-insoluble micromolecular aromatic hydrocarbon or chlorinated aromatic hydrocarbon and hydrochloride or sulfate of alkali metal. The method has the advantages of being simple, high in separation efficiency, high in recovery rate, high in recovered aniline concentration and the like, stable phase splitting of aniline water generated by the DAM refining unit can be achieved, and recovered aniline can be directly used as a raw material for producing DAM.

Description

technical field

[0001] The invention belongs to the technical field of DAM preparation and separation, and mainly relates to a method for recycling excess aniline in the preparation process of diphenylmethane series diamines and polyamines. Background technique

[0002] The production of diamines and polyamines (DAM) of the diphenylmethane series by the reaction of aniline with formaldehyde in the presence of an acid catalyst is generally known, the mixture of said diamines and polyamines being mainly widely used in the production of the corresponding Mixture of diisocyanates and polyisocyanates. According to the prior art, the preparation process of diamines and polyamines of the diphenylmethane series mainly includes the reaction of aniline and formaldehyde under an acidic catalyst to obtain a reaction liquid, and then neutralizes with lye and washes with water to obtain an organic compound containing diamines and polyamines. After that, DAM and aniline water are separate...

Examples

Embodiment 1

[0058] The phase separation process of aniline water during DAM preparation and DAM refining:

[0059] a) Aniline and hydrochloric acid are mixed in a static mixer to form aniline hydrochloride. The molar ratio of hydrochloric acid to aniline is 0.20, and then mixed with formaldehyde with a mass concentration of 37% and reacted at 60° C. for 30 minutes. The molar ratio of formaldehyde to aniline is 0.48, Obtain diamine and polyamine reaction solution containing diaminodiphenyl series;

[0060] b) Add 50wt% sodium hydroxide aqueous solution to the reaction solution in step a) according to 1.1 times the molar weight of hydrochloric acid for neutralization, carry out phase separation in a stratifier, and use 90°C hot pure water to neutralize the crude product after neutralization The amine organic phase is washed, and then the phases are separated again to obtain the refined polyamine organic phase comprising aniline and water after washing;

[0061] c) under the absolute pressu...

Embodiment 2

[0069] The phase separation process of aniline water during DAM preparation and DAM refining:

[0070] a) Aniline and hydrochloric acid are mixed in a static mixer to form aniline hydrochloride. The molar ratio of hydrochloric acid to aniline is 0.30, and then mixed with a 50% aqueous solution of formaldehyde at a mass concentration of 65°C for 40 minutes. The molar ratio of formaldehyde to aniline is 0.43 , to obtain diamine and polyamine reaction solutions containing diaminodiphenyl series;

[0071] b) Add 50wt% sodium hydroxide aqueous solution to the reaction solution in step a) according to 1.05 times the molar weight of hydrochloric acid for neutralization, carry out phase separation in a stratifier, and use 95°C hot pure water to neutralize the crude product after neutralization The amine organic phase is washed, and then the phases are separated again to obtain a refined polyamine organic phase comprising aniline and water;

[0072] c) stripping and distilling the ref...

Embodiment 3

[0085] The phase separation process of aniline water during DAM preparation and DAM refining:

[0086] a) Aniline and hydrochloric acid are mixed in a static mixer to form aniline hydrochloride. The molar ratio of hydrochloric acid to aniline is 0.30, and then mixed with a 50% aqueous solution of formaldehyde at a mass concentration of 65°C for 40 minutes. The molar ratio of formaldehyde to aniline is 0.38 , to obtain diamine and polyamine reaction solutions containing diaminodiphenyl series;

[0087] b) Add 50% sodium hydroxide solution to the reaction solution in step a) according to 1.15 times the molar weight of hydrochloric acid for neutralization, carry out phase separation in a stratifier, and use 85°C hot pure water to neutralize the crude product after neutralization The amine organic phase is washed, and then the phases are separated again to obtain a refined polyamine organic phase comprising aniline and water;

[0088] c) under the absolute pressure of 4kPa, the r...

technical field

[0001] The invention belongs to the technical field of DAM preparation and separation, and mainly relates to a method for recycling excess aniline in the preparation process of diphenylmethane series diamines and polyamines. Background technique

[0002] The production of diamines and polyamines (DAM) of the diphenylmethane series by the reaction of aniline with formaldehyde in the presence of an acid catalyst is generally known, the mixture of said diamines and polyamines being mainly widely used in the production of the corresponding Mixture of diisocyanates and polyisocyanates. According to the prior art, the preparation process of diamines and polyamines of the diphenylmethane series mainly includes the reaction of aniline and formaldehyde under an acidic catalyst to obtain a reaction liquid, and then neutralizes with lye and washes with water to obtain an organic compound containing diamines and polyamines. After that, DAM and aniline water are separate...

Examples

Embodiment 1

[0058] The phase separation process of aniline water during DAM preparation and DAM refining:

[0059] a) Aniline and hydrochloric acid are mixed in a static mixer to form aniline hydrochloride. The molar ratio of hydrochloric acid to aniline is 0.20, and then mixed with formaldehyde with a mass concentration of 37% and reacted at 60° C. for 30 minutes. The molar ratio of formaldehyde to aniline is 0.48, Obtain diamine and polyamine reaction solution containing diaminodiphenyl series;

[0060] b) Add 50wt% sodium hydroxide aqueous solution to the reaction solution in step a) according to 1.1 times the molar weight of hydrochloric acid for neutralization, carry out phase separation in a stratifier, and use 90°C hot pure water to neutralize the crude product after neutralization The amine organic phase is washed, and then the phases are separated again to obtain the refined polyamine organic phase comprising aniline and water after washing;

[0061] c) under the absolute pressu...

Embodiment 2

[0069] The phase separation process of aniline water during DAM preparation and DAM refining:

[0070] a) Aniline and hydrochloric acid are mixed in a static mixer to form aniline hydrochloride. The molar ratio of hydrochloric acid to aniline is 0.30, and then mixed with a 50% aqueous solution of formaldehyde at a mass concentration of 65°C for 40 minutes. The molar ratio of formaldehyde to aniline is 0.43 , to obtain diamine and polyamine reaction solutions containing diaminodiphenyl series;

[0071] b) Add 50wt% sodium hydroxide aqueous solution to the reaction solution in step a) according to 1.05 times the molar weight of hydrochloric acid for neutralization, carry out phase separation in a stratifier, and use 95°C hot pure water to neutralize the crude product after neutralization The amine organic phase is washed, and then the phases are separated again to obtain a refined polyamine organic phase comprising aniline and water;

[0072] c) stripping and distilling the ref...

Embodiment 3

[0085] The phase separation process of aniline water during DAM preparation and DAM refining:

[0086] a) Aniline and hydrochloric acid are mixed in a static mixer to form aniline hydrochloride. The molar ratio of hydrochloric acid to aniline is 0.30, and then mixed with a 50% aqueous solution of formaldehyde at a mass concentration of 65°C for 40 minutes. The molar ratio of formaldehyde to aniline is 0.38 , to obtain diamine and polyamine reaction solutions containing diaminodiphenyl series;

[0087] b) Add 50% sodium hydroxide solution to the reaction solution in step a) according to 1.15 times the molar weight of hydrochloric acid for neutralization, carry out phase separation in a stratifier, and use 85°C hot pure water to neutralize the crude product after neutralization The amine organic phase is washed, and then the phases are separated again to obtain a refined polyamine organic phase comprising aniline and water;

[0088] c) under the absolute pressure of 4kPa, the r...

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