CN1318477C - Process for preparation of biodegradable corrosion-scale inhibitor poly-aspartic acid - Google Patents

Abstract

The invention belongs to the technical field of chemical industry, and specifically relates to a preparation method of polyaspartic acid, a biodegradable corrosion and scale inhibitor. The dry matter of maleic acid amine is obtained, then polycondensed into polysuccinimide, and finally hydrolyzed into polyaspartic acid in the presence of alkali. The invention is a homopolymer containing amide group and carboxyl group, which has good scale-inhibiting and dispersing ability for various scales and good corrosion-inhibiting performance. It can be widely used in circulating cooling water system, boiler water, oilfield water, seawater desalination, etc.

Description

Preparation method of biodegradable corrosion and scale inhibitor polyaspartic acid

technical field

The invention belongs to the technical field of chemical industry, and specifically relates to a preparation method of polyaspartic acid, a biodegradable corrosion and scale inhibitor. The corrosion and scale inhibitor is a phosphorus-free low molecular weight homopolymer, belonging to the Green and environment-friendly, biodegradable corrosion and scale inhibitor, used for scale and corrosion inhibition treatment of water quality.

Background technique

In all areas involved in water treatment, fouling and corrosion can have serious consequences for production, reducing productivity and even causing downtime. For example, in industrial circulating cooling water systems, CaCO ₃ is the most common scale, which often leads to scaling on the inner surface of equipment pipes, affecting water flow and heat transfer efficiency. In severe cases, it can also lead to pipe blockage and shutdown. Corrosion will damage equipment and equipment. Pipelines cause serious damage and reduce normal service life. In the paper industry, CaCO ₃ and BaSO ₄ are common scales in digesters, raw liquid pipelines, drifting devices and extraction devices. Reduce product quality and production capacity. In the petroleum industry, CaCO ₃ , CaSO ₄ , and BaSO ₄ are the main components of scale, which can cause a decrease in production capacity. In seawater reverse osmosis desalination, CaSO ₄ , BaSO ₄ , and SrSO ₄ are the main components of scale. These scales will block the membrane, resulting in reduced membrane flux, decreased production capacity, shortened membrane life, and increased production costs. cause production downtime. Therefore, the antiscaling treatment of industrial water has always been a research topic that people pay close attention to. Adding antiscalant for antiscaling treatment is a relatively convenient and efficient method among many antiscaling methods.

At present, phosphorus-based formulas account for a large proportion of corrosion and scale inhibitors in my country. With the improvement of human environmental awareness and stricter environmental regulations, many countries have begun to limit phosphorus emissions, which has promoted the rapid development of low-phosphorus and phosphorus-free formulas. , Low-phosphorus, phosphorus-free green water treatment agents have become a hot topic in the development of water treatment agents at home and abroad.

In the existing technology, U.S. Patent No. 4,839,461 proposes a preparation method for preparing polyaspartic acid. Maleic anhydride is dissolved in an aqueous solution, and converted into an amine salt of maleic acid by dripping ammonia water, and then heated at 125° C. At ~145°C, it is directly thermally condensed into polysuccinimide, and then hydrolyzed under the action of sodium hydroxide to polymerize into polyaspartic acid. US5,296,578 raises the temperature of thermal polycondensation in the above reaction to 220° C. to 260° C. to increase the yield of polysuccinimide. US5,714,558 reports that in a pressure vessel, water or an organic solvent is used as a medium, maleic anhydride and gaseous ammonia are added, the temperature is raised to 130°C to 300°C, and the reaction is 5 minutes to 5 hours to generate polysuccinic acid imide. The solvent is directly hydrolyzed into polyaspartic acid. If an organic solvent is used as the solvent, the organic solvent needs to be separated and then hydrolyzed into polyaspartic acid. The material produced by the process is very difficult to handle and the equipment requirements are extremely high.

Chinese patent CN 1398799A hydrolyzes it into maleic acid, then reacts it with ammonia water to generate amine salt of maleic acid, conducts thermal condensation polymerization of amine salt of maleic acid at a certain temperature to obtain polysuccinamide, separates and dries to obtain polysuccinamide, Then, dehydration and cyclization are performed at a certain temperature to generate polysuccinimide, and finally, the sodium salt of polyaspartic acid is hydrolyzed under the action of aqueous sodium hydroxide solution. At present, there is no report on the preparation method of polyaspartic acid, a biodegradable corrosion and scale inhibitor.

Contents of the invention

The object of the present invention is to provide a preparation method of the antiscalant polyaspartic acid with short process steps, convenient process treatment and simple equipment.

The preparation method of the biodegradable corrosion and scale inhibitor polyaspartic acid proposed by the present invention is to use maleic anhydride as raw material, generate maleic acid through alkaline hydrolysis, obtain maleic acid amine through drying treatment, and then carry out polymerization reaction Generate polysuccinimide, and finally hydrolyze in the presence of alkali to generate the sodium salt of polyaspartic acid. The specific steps are: first hydrolyze maleic anhydride to maleic acid, then cool it, control the reaction temperature at 0-20°C, add 25% ammonia water to generate an aqueous solution of maleic amine; The aqueous solution is dried by a spray dryer to obtain white ammonium maleate, and the temperature is controlled at 120°C to 180°C; the dried ammonium maleate is placed in a pressure vessel for polycondensation reaction, and the temperature is controlled at 200°C to 240°C. for 3 to 5 hours, and the pressure is 0.4 to 0.6 MPa to obtain polysuccinimide; then hydrolyze polysuccinimide with sodium hydroxide aqueous solution, control the reaction temperature at 70°C to 90°C, and obtain reddish-brown viscous The solid content of the polyaspartic acid solution can be adjusted by controlling the water content.

In the present invention, the molar ratio of maleic acid to ammonia (25% wt. ammonia water) is 1:1.2˜1:2.

In the present invention, the molar ratio of polysuccinimide to sodium hydroxide is 1:1˜1:1.2.

In U.S. Patent No. 4,839,461 and U.S. Patent No. 5,296,578, in the process of polysuccinimide thermal condensation polymerization of maleic acid amine, because the aqueous solution is first polymerized, and then slowly dehydrated into polysuccinimide, the process begins It is easy to produce foaming, viscous substances that are extremely difficult to stir, and then produce hard solid substances that adhere to the equipment, making it very troublesome to handle and extremely demanding on equipment. In the present invention, maleic acid amine is dried by a spray dryer, and then placed in a pressure vessel for thermal polycondensation. Since the polycondensation is carried out in an anhydrous state, the viscous substance that is extremely difficult to stir and the sticky substance attached to the equipment are avoided. Hard solid substance.

In the present invention, since the ammonium maleate is directly placed in the pressure vessel, the polymerization and dehydration are carried out synchronously by controlling the pressure, the process and equipment are simpler, and the process and process time are greatly shortened.

The invention has good scale inhibition effect on CaCO ₃ , CaSO ₄ , BaSO ₄ , SrSO ₄ , especially high tolerance to calcium, obvious stability to chlorine and iron ions, and strong heat resistance , Can be widely used in circulating cooling water systems, boiler water, oilfield water, seawater desalination, etc.

Detailed ways

The present invention is further described below through a series of embodiments.

Example 1:

Add 196g of maleic anhydride to a three-necked flask equipped with a stirring and thermometer, then add 98ml of water, then heat in a water bath to 55°C to 80°C, stir for 30 minutes after the maleic anhydride dissolves, then cool to about 5°C, Stirring was stopped, and 272 g of 25% ammonia solution was slowly added. Dry this liquid in a spray dryer at a temperature of 160°C to obtain white ammonium maleate, then place the ammonium maleate in a pressure vessel to stir and heat it to about 220°C with an oil bath, and maintain the pressure at 0.4MPa. After 5 hours, polysuccinimide was obtained. Under the condition of 50℃～80℃, polysuccinimide is hydrolyzed into sodium polyaspartic acid with 20% aqueous sodium hydroxide solution, and a reddish-brown viscous liquid with a solid content of not less than 35% is obtained, namely A solution of polyaspartic acid was obtained.

Example 2:

Add 196g of maleic anhydride to a three-necked flask equipped with a stirring and thermometer, then add 98ml of water, then heat in a water bath to 55°C to 80°C, stir for 30 minutes after the maleic anhydride dissolves, then cool to about 5°C, Stirring was stopped, and 163 g of 25% aqueous ammonia solution was slowly added to generate amine maleate. Dry the maleic ammonium liquid in a spray dryer at 160°C to obtain white maleic ammonium, then place the maleic ammonium in a pressure vessel and heat it to about 240°C with an oil bath, and maintain the pressure at 0.5 MPa, and reacted for 4 hours to obtain polysuccinimide. Cool to 50°C-80°C, add 20% sodium hydroxide aqueous solution to hydrolyze to polyaspartic acid sodium salt, and obtain a reddish-brown viscous liquid with a solid content of not less than 35%, namely polyaspartic acid solution.

Example 3:

Add 294g of maleic anhydride to a three-necked flask equipped with a stirring and thermometer, then add 140ml of water, then heat in a water bath to 55°C-80°C, stir for 30 minutes after the maleic anhydride dissolves, then cool to about 5°C, Stop stirring, slowly add 25% ammonia solution 306g, generate maleic acid amine. Dry the ammonium maleate liquid in a spray dryer at 160°C to obtain white ammonium maleate, then place the ammonium maleate in a pressure vessel and heat it to about 230°C with an oil bath, maintaining the pressure at 0.5MPa , Reacted for 3 hours to obtain polysuccinimide. Cool to 50°C-80°C, add 20% sodium hydroxide aqueous solution to hydrolyze to polyaspartic acid sodium salt, and obtain a reddish-brown viscous liquid with a solid content of not less than 35%, namely polyaspartic acid solution.

Example 4:

Add 294g of maleic anhydride to a three-necked flask equipped with a stirring and thermometer, then add 140ml of water, then heat in a water bath to 55°C-80°C, stir for 30 minutes after the maleic anhydride dissolves, then cool to about 5°C, Stirring was stopped, and 245 g of 25% aqueous ammonia solution was slowly added to generate amine maleate. Dry the maleic ammonium liquid in a spray dryer at 170°C to obtain white maleic ammonium, then place the maleic ammonium in a pressure vessel and heat it to about 200°C with an oil bath, and maintain the pressure at 0.4 MPa, react for 5 hours to obtain polysuccinimide. Cool to 50°C-80°C, add 20% sodium hydroxide aqueous solution to hydrolyze to polyaspartic acid sodium salt, and obtain a reddish-brown viscous liquid with a solid content of not less than 35%, namely polyaspartic acid solution.

Claims (3)

1, a kind of preparation method of biodegradable corrosion and scale inhibitor polyaspartic acid, it is characterized in that concrete steps are: at first maleic anhydride is hydrolyzed to be maleic acid, then it is cooled, control reaction temperature is 0- 20°C, add 25% ammonia water to generate an aqueous solution of ammonium maleate; then dry the aqueous solution of ammonium maleate through a spray dryer to obtain white ammonium maleate, and the temperature is controlled at 120°C to 180°C; the dried Ammonium maleate is placed in a pressure vessel to undergo polycondensation reaction, the temperature is controlled at 200°C to 240°C, the reaction time is 3 to 5 hours, and the pressure is 0.4 to 0.6MPa to obtain polysuccinimide; then polysuccinimide The amine is hydrolyzed with 20% aqueous sodium hydroxide solution, and the reaction temperature is controlled at 70°C to 90°C to obtain a reddish-brown viscous polyaspartic acid solution. 2. The method for preparing the biodegradable corrosion and scale inhibitor polyaspartic acid according to claim 1, characterized in that the molar ratio of maleic acid to ammonia water is 1:1.2-1:2. 3. The method for preparing the biodegradable corrosion and scale inhibitor polyaspartic acid according to claim 1, characterized in that the molar ratio of polysuccinimide to sodium hydroxide is 1:1-1:1.2.