A method for recovering hydrochloride

Abstract

This invention relates to the field of hydrochloride recovery technology, specifically a method for recovering hydrochloride. Water is used as an extractant to separate 4,4'-diaminodiphenylmethane from the reaction solution. Then, chlorinated organic compounds are used as an extractant to separate water from the first recovery solution, yielding a second recovery solution. The second recovery solution is heated and evaporated to remove the chlorinated organic compounds, precipitating out hydrochloride containing only aniline hydrochloride and MDA hydrochloride. The recovery method is simple to operate, has low environmental requirements, and achieves a hydrochloride recovery rate of up to 95%.

Description

Technical Field

[0001] This invention relates to the field of hydrochloric acid recovery technology, specifically a method for recovering hydrochloric acid. Background Technology

[0002] In the process of producing 4,4'-diaminodiphenylmethane from aniline, formaldehyde, and hydrochloric acid, to obtain high-purity 4,4'-diaminodiphenylmethane, an alkaline solution is usually mixed with the 4,4'-diaminodiphenylmethane reaction solution to neutralize the MDA hydrochloride and aniline hydrochloride present in the reaction solution. This results in a waste of chemical resources. Therefore, how to separate MDA hydrochloride and aniline hydrochloride from the 4,4'-diaminodiphenylmethane reaction solution is of great significance for the recovery of hydrochloride from chemical raw materials. Summary of the Invention

[0003] This invention provides a method for recovering hydrochloride.

[0004] The technical solution of this invention is as follows:

[0005] A method for recovering hydrochloride salts includes the following steps:

[0006] Aniline, formaldehyde, and hydrochloric acid are mixed to produce a reaction solution containing 4,4'-diaminodiphenylmethane and hydrochloride.

[0007] The reaction solution is mixed with water at a weight ratio of 0.5-7:1. After extraction, the supernatant is retained to obtain a first recovery solution containing hydrochloride and water.

[0008] The first recovered liquid is mixed with chlorinated organic matter at a weight ratio of 1-5:1. After extraction, the lower layer is retained to obtain a second recovered liquid containing hydrochloride and chlorinated organic matter.

[0009] Heating the second recovery solution precipitates hydrochloride.

[0010] The chlorinated organic compound contains chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide in a weight ratio of 1:0.5-0.7:0.2-0.8:0.1-0.3.

[0011] In the recovery method described above, the weight ratio of the reaction solution to water is 7:1.

[0012] In the recovery method described above, the weight ratio of the first recovered liquid to the chlorinated organic matter is 3:1.

[0013] In the recycling method described above, the weight ratio of the mixture of chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide is 1:0.6:0.6:0.2.

[0014] In the recovery method described above, the temperature is controlled at 20-30°C during the process of obtaining the first recovered liquid; preferably, the temperature is 25°C.

[0015] In the recovery method described above, the temperature is controlled at 15-35°C during the operation to obtain the second recovered liquid; preferably, the temperature is 25°C.

[0016] In the recovery method described above, during the heating of the second recovered liquid, the heating temperature is controlled at 58-86°C and the heating time is 10-15 min; preferably, the heating temperature is 77°C and the heating time is 12 min.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention provides a method for recovering hydrochloride. Water is used as the extractant to separate 4,4'-diaminodiphenylmethane from the reaction solution. Then, chlorinated organic compounds are used as the extractant to separate water from the first recovery solution, yielding a second recovery solution. The second recovery solution is heated and evaporated to remove the chlorinated organic compounds, precipitating out hydrochloride containing only aniline hydrochloride and MDA hydrochloride. The recovery method is simple to operate, has low environmental requirements, and achieves a hydrochloride recovery rate of up to 95%. Detailed Implementation

[0019] Example

[0020] This embodiment provides a method for recovering hydrochloride, including the following steps:

[0021] Aniline, formaldehyde, and hydrochloric acid are mixed to produce a reaction solution containing 4,4'-diaminodiphenylmethane and hydrochloride.

[0022] The reaction solution is mixed with water at a weight ratio of 0.5-7:1. After extraction, the supernatant is retained to obtain a first recovery solution containing hydrochloride and water.

[0023] The first recovered liquid is mixed with chlorinated organic matter at a weight ratio of 1-5:1. After extraction, the lower layer is retained to obtain a second recovered liquid containing hydrochloride and chlorinated organic matter.

[0024] Heating the second recovery solution precipitates hydrochloride.

[0025] The chlorinated organic compound contains chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide in a weight ratio of 1:0.5-0.7:0.2-0.8:0.1-0.3.

[0026] Specifically:

[0027] Aniline, formaldehyde, and hydrochloric acid are mixed to generate a reaction solution containing 4,4'-diaminodiphenylmethane, aniline hydrochloride, and MDA hydrochloride.

[0028] The reaction solution is mixed with water, and the temperature is controlled at 20-30℃, preferably 25℃. After extraction in an extraction tower, a first recovery solution is obtained. The purpose of using water as the extractant is to separate 4,4'-diaminodiphenylmethane by water extraction and recover the hydrochloride. The first recovery solution contains aniline hydrochloride, MDA hydrochloride, and water.

[0029] The weight ratio of the reaction solution to water is 0.5-7:1, with a preferred weight ratio of 7:1, which results in a higher extraction rate.

[0030] Then, the first recovered liquid is mixed with chlorinated organic compounds, and the temperature is controlled at 15-35℃, preferably 25℃. After extraction in an extraction tower, a second recovered liquid is obtained. The purpose of using chlorinated organic compounds as the extractant is to separate the water from the first recovered liquid and recover the extract hydrochloride. The second recovered liquid contains aniline hydrochloride and MDA hydrochloride, as well as chlorinated organic compounds.

[0031] The weight ratio of the first recovered liquid to the chlorinated organic matter is 1-5:1, with a preferred weight ratio of 3:1.

[0032] The chlorinated organic compounds contain chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide. Di-n-butylamide can improve the extraction rate of chlorinated organic compounds. The mixing ratio of chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide is 1:0.5-0.7:0.2-0.8:0.1-0.3, with a preferred weight ratio of 1:0.6:0.6:0.2. Finally, the second recovery liquid is heated in a water bath at a controlled temperature of 58-86℃, preferably 77℃, for 10-15 min, preferably 12 min, to evaporate and remove the chlorinated organic compounds, yielding hydrochloride as the precipitate.

[0033] Example 1

[0034] The reaction solution was mixed with water at a weight ratio of 0.5:1, and the temperature was controlled at 20°C. After extraction in an extraction tower, the first recovered solution was obtained. Chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide were mixed at a weight ratio of 1:0.5:0.2:0.1 to obtain chlorinated organic compounds. Next, the first recovered solution and the chlorinated organic compounds were mixed at a weight ratio of 1:1, and the temperature was controlled at 15°C. After extraction in an extraction tower, the second recovered solution was obtained. The second recovered solution was heated in a water bath at a temperature of 58°C for 10 minutes to evaporate and remove the chlorinated organic compounds, and the precipitated product was hydrochloride.

[0035] The recovery rate of hydrochloride was 91%.

[0036] Example 2

[0037] The reaction solution was mixed with water at a weight ratio of 7:1, and the temperature was controlled at 30°C. After extraction in an extraction tower, the first recovered solution was obtained. Chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide were mixed at a weight ratio of 1:0.7:0.8:0.3 to obtain chlorinated organic compounds. Next, the first recovered solution was mixed with the chlorinated organic compounds at a weight ratio of 5:1, and the temperature was controlled at 35°C. After extraction in an extraction tower, the second recovered solution was obtained. The second recovered solution was heated in a water bath at a temperature of 86°C for 15 minutes to evaporate and remove the chlorinated organic compounds, and the precipitated product was hydrochloride.

[0038] The recovery rate of hydrochloride was 93%.

[0039] Example 3

[0040] The reaction solution was mixed with water at a weight ratio of 7:1, and the temperature was controlled at 25°C. After extraction in an extraction tower, the first recovered solution was obtained. Chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide were mixed at a weight ratio of 1:0.6:0.6:0.2 to obtain chlorinated organic compounds. Next, the first recovered solution was mixed with the chlorinated organic compounds at a weight ratio of 3:1, and the temperature was controlled at 25°C. After extraction in an extraction tower, the second recovered solution was obtained. The second recovered solution was heated in a water bath at 77°C for 12 minutes to evaporate and remove the chlorinated organic compounds, and the precipitated product was hydrochloride.

[0041] The recovery rate of hydrochloride was 95%.

[0042] To verify the hydrochloride recovery effect of the method provided in this application, comparative examples 1-3 are also provided in this application to compare and verify the hydrochloride recovery effect of different methods.

[0043] Comparative Example 1

[0044] The reaction solution was mixed with water at a weight ratio of 7:1, and the temperature was controlled at 30°C. After extraction in an extraction tower, the first recovered solution was obtained. Chloroform, carbon tetrachloride, and dichloroethane were mixed at a weight ratio of 1:0.7:0.8 to obtain chlorinated organic compounds. Next, the first recovered solution was mixed with the chlorinated organic compounds at a weight ratio of 5:1, and the temperature was controlled at 35°C. After extraction in an extraction tower, the second recovered solution was obtained. The second recovered solution was heated in a water bath at a temperature of 86°C for 15 minutes to evaporate and remove the chlorinated organic compounds, and the precipitated product was hydrochloride.

[0045] The recovery rate of hydrochloride was 87%.

[0046] Comparative Example 2

[0047] The reaction solution was mixed with water at a weight ratio of 7:1, and the temperature was controlled at 30°C. After extraction in an extraction tower, the first recovered solution was obtained. Carbon tetrachloride, dichloroethane, and di-n-butylamide were mixed at a weight ratio of 0.7:0.8:0.3 to obtain chlorinated organic compounds. Next, the first recovered solution was mixed with the chlorinated organic compounds at a weight ratio of 5:1, and the temperature was controlled at 35°C. After extraction in an extraction tower, the second recovered solution was obtained. The second recovered solution was heated in a water bath at a temperature of 86°C for 15 minutes to evaporate and remove the chlorinated organic compounds, and the precipitated product was hydrochloride.

[0048] The recovery rate of hydrochloride was 89%.

[0049] Comparative Example 3

[0050] The reaction solution was mixed with water at a weight ratio of 7:1, and the temperature was controlled at 30°C. After extraction in an extraction tower, the first recovered solution was obtained. Carbon tetrachloride and dichloroethane were mixed at a weight ratio of 0.7:0.8 to obtain chlorinated organic compounds. Next, the first recovered solution and the chlorinated organic compounds were mixed at a weight ratio of 5:1, and the temperature was controlled at 35°C. After extraction in an extraction tower, the second recovered solution was obtained. The second recovered solution was heated in a water bath at a temperature of 86°C for 15 minutes to evaporate and remove the chlorinated organic compounds, and the precipitated product was hydrochloride.

[0051] The recovery rate of hydrochloride was 84%.

[0052] This embodiment provides a method for recovering hydrochloride. Water is used as an extractant to separate 4,4'-diaminodiphenylmethane from the reaction solution. Then, chlorinated organic compounds are used as an extractant to separate water from the first recovery solution, resulting in a second recovery solution. The second recovery solution is heated and evaporated to remove the chlorinated organic compounds, precipitating out hydrochloride containing only aniline hydrochloride and MDA hydrochloride. The recovery method is simple to operate, has low environmental requirements, and achieves a hydrochloride recovery rate of up to 95%.

Claims

1. A method for recovering hydrochloride, characterized in that, Includes the following steps: Aniline, formaldehyde, and hydrochloric acid are mixed to generate a reaction solution containing 4,4'-diaminodiphenylmethane, aniline hydrochloride, and MDA hydrochloride. The reaction solution is mixed with water at a weight ratio of 7:1, and the temperature is controlled at 30°C. After extraction in an extraction tower, a first recovery solution is obtained. Chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide are mixed at a weight ratio of 1:0.7:0.8:0.3 to obtain chlorinated organic compounds. The first recovery solution is mixed with the chlorinated organic compounds at a weight ratio of 5:1, and the temperature is controlled at 35°C. After extraction in an extraction tower, a second recovery solution is obtained. The second recovery solution is heated in a water bath at 86°C for 15 minutes to evaporate and remove the chlorinated organic compounds, precipitating out hydrochloride.

2. A method for recovering hydrochloride, characterized in that, Includes the following steps: Aniline, formaldehyde, and hydrochloric acid are mixed to generate a reaction solution containing 4,4'-diaminodiphenylmethane, aniline hydrochloride, and MDA hydrochloride. The reaction solution is mixed with water at a weight ratio of 7:1, and the temperature is controlled at 25°C. After extraction in an extraction tower, a first recovery solution is obtained. Chloroform, carbon tetrachloride, dichloroethane, and di-n-butylamide are mixed at a weight ratio of 1:0.6:0.6:0.2 to obtain chlorinated organic compounds. The first recovery solution is mixed with the chlorinated organic compounds at a weight ratio of 3:1, and the temperature is controlled at 25°C. After extraction in an extraction tower, a second recovery solution is obtained. The second recovery solution is heated in a water bath at 77°C for 12 minutes to evaporate and remove the chlorinated organic compounds, precipitating out hydrochloride.