CN112661962B - Method for treating maleic anhydride ammoniation mother liquor - Google Patents

Abstract

The invention discloses a method for treating maleic anhydride ammoniation mother liquor, which comprises the steps of concentrating the mother liquor to 70-80% of solid content, adjusting the pH value of the mixed mother liquor to 6-7 by using ammonia water, converting various substance components contained in the mother liquor into condensable ammonium salt of butenedioic acid or an aspartic acid monomer, and synthesizing a polyaspartic acid aqueous solution product through spray drying, high-temperature condensation and alkaline hydrolysis. The method can effectively utilize each component in the mother solution, not only secondarily purify the product and improve the product quality, but also has no three wastes, is environment-friendly, and is suitable for industrial popularization.

Description

Method for treating maleic anhydride ammoniation mother liquor

Technical Field

The invention relates to the technical field of environmental protection engineering, in particular to a method for treating maleic anhydride ammoniation mother liquor.

Background

The scale inhibitor can effectively control the scaling of metal ions such as calcium, magnesium and iron carbonate, sulfate, silicate and phosphate, prevent the metal scaling phenomenon in equipment such as a boiler, a cooling water system, a water injection secondary oil extraction system, a flue gas desulfurization system, a seawater desalination device and the like, and prevent the corrosion and the blockage of a pipeline.

The scale inhibitors are various, but with the increasing awareness of environmental protection of human beings, Polyaspartic Acid (PASP) is used as a non-toxic, pollution-free and biodegradable green environment-friendly scale inhibitor to gradually replace the traditional organic phosphonic acids and polycarboxylic acids scale inhibitors. Compared with the traditional corrosion and scale inhibitor, the PASP has better corrosion inhibition, scale inhibition and dispersion performances and extremely high biodegradability. The synthesis research aiming at PASP has become a key point for the research and development of water treatment agents in various countries. As early as the 90's of the 20 th century, the Donla corporation first developed polyaspartic acid to receive the United states President Green chemical challenge prize in 1996. The synthesis and performance of polyaspartic acid have been studied competitively since this country. To date, domestic and foreign research on the synthesis of polyaspartic acid has focused mainly on two directions: firstly, thermal polymerization using L-aspartic acid as raw material, and secondly, thermal polymerization using maleic anhydride or maleic acid and its derivatives as raw material. The second synthesis mode has low production cost, easily obtained raw materials, is more beneficial to large-scale production and has stronger market competitiveness. For example, zhanghouli and the like propose a synthesis method (application chemical industry, 12 months in 2011 and 12 periods in 40 volumes) for generating PASP scale inhibitor by taking maleic anhydride and ammonium carbonate as raw materials, adopting a low-temperature nitrogen fixation and high-temperature polymerization mode to generate intermediate polysuccinimide, and then carrying out alkaline hydrolysis;

patent CN108373536B proposes a synthesis method for synthesizing modified polyaspartic acid with schiff base structure by using maleic anhydride as raw material.

In the actual production, in the process of synthesizing an intermediate poly (succinic acid) (PSI), maleic anhydride cannot be completely converted into PSI, unreacted maleic acid and fumaric acid can be remained, impurities such as malic acid and iminodisuccinic acid can be generated, the product quality is seriously influenced, and raw material waste is caused; in the actual production process, although PSI and acidic mother liquor can be separated by a water washing mode, the production cost is increased to a certain extent by the generation of a large amount of acidic waste liquor, and the environmental safety is influenced. Aiming at the treatment scheme of the acidic mother liquor generated by synthesizing the polyaspartic acid product by a maleic anhydride ammoniation method, no proper method exists so far. Therefore, the invention provides a method for treating acidic mother liquor for synthesizing PASP from maleic anhydride, which can effectively realize reasonable recycling of raw materials and simultaneously eliminate the influence of impurities such as malic acid, iminodisuccinic acid and the like on the product performance and quality.

Disclosure of Invention

The invention aims to provide a method for treating maleic anhydride ammoniation mother liquor so as to solve the technical problems.

In order to achieve the purpose, the invention adopts the following technical scheme: a treatment method of maleic anhydride ammoniation mother liquor specifically comprises the following steps:

(1) separating the intermediate polysuccinimide PSI, washing with water to obtain a maleic anhydride ammoniated mother liquor, carrying out negative pressure external evaporation and concentration on the maleic anhydride ammoniated mother liquor until the solid content is 70-80%, then adding ammonia water with a certain content into the mother liquor under the stirring condition, and adjusting the pH value of the system to 6-7;

(2) carrying out spray drying on the mixed maleic anhydride ammoniation mother liquor obtained in the step (1) at 180-220 ℃ to obtain solid powder;

(3) transferring the solid powder into a solid reactor, carrying out thermal polymerization for 1-3 h at 220-260 ℃ to obtain earthy yellow solid particles, crushing to obtain polysuccinimide PSI with the purity of more than 99%, and hydrolyzing to obtain a polyaspartic acid aqueous solution product.

As a further scheme of the invention, the solid main components of the maleic anhydride ammoniation mother liquor in the step (1) comprise: 25-30% of butenedioic acid, 10-15% of aspartic acid, 45-50% of iminodisuccinic acid and 5-20% of malic acid.

As a further scheme of the invention, the content of the ammonia water in the step (1) is 20-25%, and the external steaming negative pressure is-0.09 to-0.07 MPa.

As a further scheme of the invention, the water content of the solid powder in the step (2) is 2-5%.

As a further aspect of the present invention, the negative pressure solid state reactor in the step (3) is any one of a stirred reactor, a rotary reactor and a fluidized bed reactor.

The invention has the beneficial effects that: the invention provides a method for converting mother liquor in the process of synthesizing polyaspartic acid into polyaspartic acid and malic acid through treatment; the method effectively improves the utilization rate of the raw materials, converts the butenedioic acid and the aspartic acid in the mother liquor into PASP, and converts the iminodisuccinic acid into the aspartic acid and the malic acid; in the method, malic acid can be decomposed into water and butenedioic acid in the reaction process for continuous reaction, no residue is generated, the product is secondarily purified, the product quality is improved, three wastes are not generated, and the method is environment-friendly; the method utilizes ammonia water to adjust the pH value of the system, so that all substance components in the mother liquor are converted into ammonium salt of the butenedioic acid or aspartic acid which can be condensed through a certain process reaction, the operation is simple, and the industrial production is favorably realized.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention uses part of raw materials and equipment with the following specifications:

the spray dryer is an LPG-150 type liquid centrifugal spray granulation dryer; the solid reactor is a rotary reactor; the solid content of the mother liquor is 26.43%, the pH (stock solution) is 4.31, and the main solid components comprise: 26% of butenedioic acid, 13% of aspartic acid, 46% of iminodisuccinic acid and 15% of malic acid (determined by nuclear magnetism).

Example 1

(1) Adding 2000kg of mother liquor containing 26.43% of solid content into an external steaming kettle, starting stirring, externally steaming water under the pressure of-0.09 MPa, concentrating until the solid content is 70.54%, and then dropwise adding 715kg of ammonia water containing 20% of solid content to obtain 1465kg of mother liquor, wherein the pH value of the system is 6.55;

(2) setting the air inlet temperature of an LPG-150 liquid centrifugal spray granulation dryer to be 190 ℃, and preparing 728kg of solid powder from the treated mother liquor through a spray dryer, wherein the water content of the particles is 9.87%;

(3) transferring all solid powder into a rotary reactor, carrying out thermal polymerization reaction for 2h at 242 +/-2 ℃, and carrying out alkaline hydrolysis on the obtained polysuccinimide powder to obtain 1660kg of a light yellow sodium polyaspartate aqueous solution with the content of 40.75 percent.

Through nuclear magnetic detection, the purity of the intermediate polysuccinimide is 99.18%, and the molecular weight of the hydrolyzed PASP is 4839 through a limit viscosity number method.

Example 2

(1) Adding 2000kg of mother liquor with the solid content of 26.43% into an external steaming kettle, starting stirring, externally steaming water under the pressure of-0.07 MPa, concentrating until the solid content is 79.26%, and then dropwise adding 633kg of ammonia water with the content of 25% to obtain 1300kg of mother liquor, wherein the pH value of the system is 7.05;

(2) setting the air inlet temperature of an LPG-150 type liquid centrifugal spray granulation dryer to be 200 ℃, and preparing the treated mother liquor into 736kg of white solid powder through a spray dryer, wherein the water content of the granules is 8.16%;

(3) transferring all solid powder into a rotary reactor, performing thermal polymerization reaction at 258 +/-2 ℃ for 3h, and performing alkaline hydrolysis on the obtained polysuccinimide powder to obtain 1715kg of a light yellow sodium polyaspartate aqueous solution with the content of 40.56 percent.

Through nuclear magnetic detection, the purity of the intermediate polysuccinimide is 99.31 percent, and the molecular weight of the hydrolyzed PASP is 4583 by a limit viscosity number method.

Comparative example conventional Process

(1) Adding 1000kg of mother liquor with the content of 26.43% into an external steaming kettle, externally steaming and concentrating under the pressure of-0.07 MPa until the mother liquor is nearly dry, then transferring into an oven, drying at 70 +/-5 ℃ to obtain blocky solid, and crushing to obtain 264kg of solid powder.

(2) Transferring the solid powder into a rotary reactor, adding 65kg of ammonium carbonate monohydrate, stirring and heating to 200 +/-2 ℃ for reaction for 3 hours, transferring the obtained solid into a hydrolysis kettle, adding water for dissolution, filtering, adding a sodium hydroxide aqueous solution into the solid to adjust the pH value of the system to 10.2, heating and hydrolyzing for 1 hour to obtain 450kg of a light yellow sodium polyaspartate aqueous solution with the content of 40.17%.

Through nuclear magnetic detection, the product PASP content is 98.86%, the PASP molecular weight is 4744 by a limit viscosity number method, the content of the imino disuccinic acid in 423kg of the obtained filtrate is 29.55%, and the content of the malic acid is 0.34%.

As can be seen from the comparative example, the mother liquor obtained according to the conventional process technique was treated, and 125kg of iminodisuccinic acid and 1.44kg of malic acid contained therein were finally precipitated and separated in their inherent forms; in the method, the pH value of the ammoniation adjusting system is adjusted to 6-7, so that all substances such as iminodisuccinic acid and malic acid which are byproducts in the maleic anhydride ammoniated mother liquor can be effectively converted into ammonium salt of the polycondensable butene diacid or aspartic acid, the recycling of the substances is realized, and the yield of the product is improved.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (1)

1. The method for treating the maleic anhydride ammoniation mother liquor is characterized by comprising the following steps:

separating the intermediate polysuccinimide PSI and washing with water to obtain maleic anhydride ammoniated mother liquor, wherein the solid content of the mother liquor is 26.43 percent, the pH value is 4.31, and the solid components comprise: 26% of butenedioic acid, 13% of aspartic acid, 46% of iminodisuccinic acid and 15% of malic acid, and judging according to nuclear magnetism;

(1) adding 2000kg of mother liquor with the solid content of 26.43% into an external steaming kettle, starting stirring, externally steaming water under the pressure of-0.07 MPa, concentrating until the solid content is 79.26%, and then dropwise adding 633kg of ammonia water with the content of 25% to obtain 1300kg of mother liquor, wherein the pH value of the system is 7.05;

(2) setting the air inlet temperature of an LPG-150 type liquid centrifugal spray granulation dryer to be 200 ℃, and preparing 736kg of white solid powder from the treated mother liquor through a spray dryer, wherein the water content of the granules is 8.16%;

(3) transferring all solid powder into a rotary reactor, performing thermal polymerization reaction at 258 +/-2 ℃ for 3h, and performing alkaline hydrolysis on the obtained polysuccinimide powder to obtain 1715kg of a light yellow sodium polyaspartate aqueous solution with the content of 40.56 percent.