Integrated recycling method for kettle residues generated in synthesis process of 5, 5-dimethylhydantoin

Abstract

The invention relates to a method for integrally recycling kettle residues generated in the synthesis process of 5, 5-dimethylhydantoin, which comprises the following steps: 1, dissolving the kettle residues in water, and filtering an adsorbent to obtain a yellow kettle residue solution containing hydantoin; and 2, carrying out vacuum concentration on the kettle residue solution, adding a formaldehyde aqueous solution, and carrying out reaction, filtration and impurity removal to obtain the dimethylol hydantoin product. And 3, adding calcium hydroxide and a catalyst into the kettle residue solution which is obtained by filtering in the step 2 and does not contain hydantoin, and carrying out medium-high temperature reaction, concentration and recrystallization to obtain a glycine product. According to the method, the kettle residues generated in the synthesis process of the 5, 5-dimethylhydantoin are integrally recycled, firstly, the residual 5, 5-dimethylhydantoin product in the kettle residues is used for synthesizing the dihydroxy hydantoin product, then other components in the kettle residues are decomposed into glycine, and all compounds in the kettle residues are effectively utilized. No harmful'three wastes' are generated in the recycling process, so that the treatment cost of the kettle residues is saved, and the environment-friendly integrated recycling of the kettle residues is realized.

Description

Technical Field

[0001] The invention relates to an integrated recycling method for kettle residues produced in the synthesis process of 5,5-dimethylhydantoin. Background Art

[0002] 5,5-dimethylhydantoin is a widely used chemical raw material, which can be widely used in the synthesis of preservatives, disinfectants, water-soluble resin modifiers and α,α-dimethylglycine, etc. In the process of preparing 5,5-dimethylhydantoin, multiple concentration and evaporation will be carried out, which will produce a colored organic residue composed of various substances. Its main components include N-formylglycine amide, 2,5-diketopiperazine, hydantoin, hydantoin acid, glycine dipeptide, glycine, etc. The composition is complex, and the treatment effect is not obvious under the action of high temperature, hydrochloric acid and caustic soda. Therefore, the decomposition of the residue is of great environmental value and economic value. In addition, the residue contains about 50% of 5,5-dimethylhydantoin, and the reuse of this part of the material is also an important means to enhance the economic value.

[0003] At present, the main treatment method for hyaluronic acid residue is incineration, which requires extremely high treatment temperature, and the gas damage generated during the treatment process far exceeds the economic benefits, causing huge energy consumption and environmental pollution. Hyaluronic acid + formaldehyde aqueous solution 5:6 Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention aims to solve the technical problem of recycling the kettle residue produced in the synthesis process of 5,5-dimethylhydantoin, and provides an integrated recycling method of the kettle residue produced in the synthesis process of 5,5-dimethylhydantoin: A method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin, comprising the following steps: The kettle residue is dissolved in water, and filtered through activated carbon adsorption to obtain a kettle residue solution; the kettle residue solution is vacuum concentrated in a 90°C to 100°C water bath environment until no distilled water flows out, to obtain a concentrated kettle residue solution with a 55% hydantoin content; Adding formaldehyde aqueous solution to the concentrated still solution of step 1), performing vacuum reaction in a water bath, reacting 5,5-dimethylhydantoin in the still solution with formaldehyde to generate dihydroxymethylhydantoin, cooling the reaction solution to allow dihydroxymethylhydantoin to crystallize, and filtering to obtain dihydroxymethylhydantoin product and filtrate; The filtrate in step 2) is added with calcium hydroxide and a catalyst and heated in an oil bath in vacuum to 120°C-150°C, the residual components in the filtrate are hydrolyzed for 5-15h, and the crude glycine is obtained by vacuum concentration, and the glycine product is obtained after adding water for recrystallization; wherein the mass ratio of calcium hydroxide to catalyst is 100:5-30:0.1-5; wherein the catalyst is a mixture of titanium dioxide and bismuth trioxide, and the mass ratio of titanium dioxide to bismuth trioxide is 3:2-1:1.

[0005] According to the method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin as described in claim 1, it is further designed that the mass ratio of the kettle residues to water in step 1) is 1:0.5~1.5.

[0006] According to the method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin as described in claim 1, it is further designed that the reaction negative pressure in step 1) is ≥0.05MPa.

[0007] According to the method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin as described in claim 1, it is further designed that the hydantoin content in the concentrated kettle residue in step 1) is 20% to 60%, the total input mass of the formaldehyde aqueous solution in step 2) is 6:5 of the mass of hydantoin in the solution, and the formaldehyde content in the formaldehyde aqueous solution is 55%.

[0008] According to the method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin as described in claim 1, it is further designed that the formaldehyde aqueous solution in step 2) is added in 5 to 8 batches, and the material is added after the previous batch is completely dissolved and uniformly dissolved.

[0009] According to claim 1, a method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin, further designed that the water bath reaction conditions in step 2) are two-stage temperature control reactions, the first temperature control reaction: 60~100°C for feeding, the reaction time is until all the formaldehyde aqueous solution is added; the second temperature control reaction: 90~120°C for the synthesis reaction after feeding, the reaction time is 10~120min.

[0010] According to the method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin as described in claim 1, it is further designed that the cooling temperature in step 2) should be 0~20°C.

[0011] According to the method for integrated recycling of kettle residues produced during the synthesis of 5,5-dimethylhydantoin as described in claim 1, it is further designed that the total content of kettle residue organic matter in the filtrate in step 3) is ≥10%.

[0012] The beneficial effects of the present invention are: Compared with the existing still residue treatment technology, the present invention does not require high-temperature incineration and consumes a large amount of fuel, and the reaction process is safe and reliable, with low requirements on equipment. It can fully recover the organic matter in the still residue and has good economic benefits; and less wastewater is generated by the recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a flow chart of the present invention.

[0014] Figure 2 It is a data table of 4 embodiments of the present invention. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0016] like Figure 1 The method for integrated recycling of the kettle residue produced in the synthesis process of 5,5-dimethylhydantoin is carried out according to the following steps: 1. Add 1 part of the kettle residue to 0.5~1.5 parts of water and filter to obtain a kettle residue solution. Concentrate the kettle residue solution in a water bath at a reaction temperature of 95~100℃ under vacuum with a negative pressure of ≥0.1MPa to obtain a concentrated kettle residue solution with a 40%~50% hydantoin content; 2. Add 1-2 parts of 40%-60% formaldehyde aqueous solution to 1 part of concentrated kettle residual solution, and conduct vacuum reaction in a water bath. The reaction is a two-stage temperature control reaction. The first temperature control reaction: feed at 80-90℃, and the reaction time is until all the formaldehyde aqueous solution is added; the second temperature control reaction: perform the synthesis reaction after feeding at 95-105℃, and the reaction time is 30-90min. After cooling to 5-15℃, filter and remove impurities to obtain the dihydroxymethyl hydantoin product; 3. Add 8-15 parts of calcium hydroxide and 0.5-2 parts of catalyst to 100 parts of the filtrate in step 2, and heat to 120-150°C in an oil bath under vacuum for 5-15 hours. Then vacuum concentrate to obtain crude glycine, and add water for recrystallization to obtain glycine product; This specific implementation scheme provides a specific implementation scheme for the integrated recycling method of the kettle residues produced during the synthesis of 5,5-dimethylhydantoin.

[0017] The following experiments were used to verify the effect of the present invention: Example

[0018] 1. Add 1 part of the still residue to 1 part of water, filter and obtain a still residue solution. Concentrate the still residue solution in a water bath at a reaction temperature of 100°C under vacuum and at a negative pressure of 0.1 MPa to obtain a concentrated still residue solution with a 50% hydantoin content; 2. Add 0.5 parts of 40% formaldehyde aqueous solution to 1 part of concentrated kettle residual solution, and conduct vacuum reaction in a water bath. The reaction is a two-stage temperature control reaction. The first temperature control reaction: feed at 84°C, and the reaction time is until all the formaldehyde aqueous solution is added; the second temperature control reaction: perform the synthesis reaction after feeding at 100°C, and the reaction time is 40 minutes. After cooling to 10°C, filter and remove impurities to obtain the dihydroxymethyl hydantoin product; 3. Add 12.5 parts of calcium hydroxide and 1 part of catalyst (0.5 parts of titanium dioxide and 0.5 parts of bismuth trioxide) to 100 parts of the filtrate in step 2, and heat to 150°C in an oil bath under vacuum for 7.5 hours. Then vacuum concentrate to obtain crude glycine, and add water for recrystallization to obtain glycine product; Example

[0019] 1. Add 1 part of the still residue to 0.75 parts of water, filter and obtain a still residue solution. Concentrate the still residue solution in a water bath at a reaction temperature of 100°C under vacuum and at a negative pressure of 0.1 MPa to obtain a concentrated still residue solution with a 55% hydantoin content; 2. Add 0.75 parts of 50% formaldehyde aqueous solution to 1 part of concentrated kettle residual solution, and conduct vacuum reaction in a water bath. The reaction is a two-stage temperature control reaction. The first temperature control reaction: feed at 90°C, and the reaction time is until all the formaldehyde aqueous solution is added; the second temperature control reaction: conduct the synthesis reaction after feeding at 100°C, and the reaction time is 60 minutes. After cooling to 0°C, filter and remove impurities to obtain the dihydroxymethyl hydantoin product; 3. Add 10 parts of calcium hydroxide and 1 part of catalyst (0.5 parts of titanium dioxide and 0.5 parts of bismuth trioxide) to 100 parts of the filtrate in step 2, and heat to 120°C in an oil bath under vacuum for 5 hours. Then vacuum concentrate to obtain crude glycine, and add water for recrystallization to obtain glycine product; Example

[0020] 1. Add 1 part of the still residue to 1 part of water, filter and obtain a still residue solution. Concentrate the still residue solution in a water bath at a reaction temperature of 100°C under vacuum and at a negative pressure of 0.1 MPa to obtain a concentrated still residue solution with a hydantoin content of 55%; 2. Add 0.83 parts of 60% formaldehyde aqueous solution to 1 part of concentrated kettle residual solution, and conduct vacuum reaction in a water bath. The reaction is a two-stage temperature control reaction. The first temperature control reaction: feed at 90°C, and the reaction time is until all the formaldehyde aqueous solution is added; the second temperature control reaction: conduct the synthesis reaction after feeding at 100°C, and the reaction time is 60 minutes. After cooling to 0°C, filter and remove impurities to obtain the dihydroxymethyl hydantoin product; 3. Add 12 parts of calcium hydroxide and 0.75 parts of catalyst (0.45 parts of titanium dioxide and 0.3 parts of bismuth trioxide) to 100 parts of the filtrate in step 2, and heat to 150°C in an oil bath under vacuum for 15 hours. Then vacuum concentrate to obtain crude glycine, and add water for recrystallization to obtain glycine product; Example

[0021] 1. Add 1 part of the still residue to 1 part of water, filter and obtain a still residue solution. Concentrate the still residue solution in a water bath at a reaction temperature of 100°C under vacuum and at a negative pressure of 0.1 MPa to obtain a concentrated still residue solution with a 50% hydantoin content; 2. Add 1.5 parts of 55% formaldehyde aqueous solution to 1 part of concentrated kettle residual solution, and conduct vacuum reaction in a water bath. The reaction is a two-stage temperature control reaction. The first temperature control reaction: feed at 80°C, and the reaction time is until all the formaldehyde aqueous solution is added; the second temperature control reaction: perform the synthesis reaction after feeding at 102°C, and the reaction time is 60 minutes. After cooling to 5°C, filter and remove impurities to obtain the dihydroxymethyl hydantoin product; 3. Add 15 parts of calcium hydroxide and 0.5 parts of catalyst (0.3 parts of titanium dioxide and 0.2 parts of bismuth trioxide) to 100 parts of the filtrate in step 2, and heat to 150°C in an oil bath under vacuum for 12.5 hours. Then vacuum concentrate to obtain crude glycine, and add water for recrystallization to obtain glycine product; Table: The content and yield of dihydroxymethylhydantoin obtained in the experimental example, and the content and yield of glycine obtained.

[0022] like Figure 2 As shown, the present invention effectively recovers organic matter in the kettle residue with lower power consumption.

Claims

1. A method for the integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin, characterized by the following steps: 1) Dissolve the kettle residue in water, and obtain a kettle residue solution after filtration using activated carbon adsorption; vacuum concentrate the kettle residue solution in a water bath environment at 90°C to 100°C until no distilled water flows out, to obtain a concentrated kettle residue solution with a 55% hydantoin content; 2) adding the formaldehyde aqueous solution to the concentrated still solution of step 1), and performing a vacuum reaction in a water bath, wherein the 5,5-dimethylhydantoin in the still solution reacts with the formaldehyde to generate dihydroxymethylhydantoin, cooling the reaction solution to allow the dihydroxymethylhydantoin to crystallize, and filtering to obtain the dihydroxymethylhydantoin product and a filtrate; 3) adding calcium hydroxide and a catalyst to the filtrate in step 2) and heating it in an oil bath under vacuum to 120°C-150°C, hydrolyzing the residual components in the filtrate for 5-15h, concentrating under vacuum to obtain crude glycine, and adding water to recrystallize to obtain a glycine product; wherein, The mass ratio of calcium hydroxide to catalyst is 100:5~30:0.1~5; wherein the catalyst is a mixture of titanium dioxide and bismuth trioxide, and the mass ratio of titanium dioxide to bismuth trioxide is 3:2~1:

1.

2. The method for integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin according to claim 1, characterized in that The mass ratio of the kettle residue to water in step 1) is 1:0.5-1.

5.

3. The method for integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin according to claim 1, characterized in that In step 1), the reaction negative pressure is ≥ 0.05 MPa.

4. The method for integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin according to claim 1, characterized in that The content of hydantoin in the concentrated kettle residue in step 1) is 20% to 60%, the total mass of the formaldehyde aqueous solution input in step 2) is 6:5 of the mass of hydantoin in the solution, and the formaldehyde content in the formaldehyde aqueous solution is 55%.

5. The method for integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin according to claim 1, characterized in that The formaldehyde aqueous solution in step 2) is added in 5 to 8 batches, and the next batch is added after the previous batch is completely dissolved.

6. The method for integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin according to claim 1, characterized in that The water bath reaction conditions in step 2) are two-stage temperature control reactions, the first temperature control reaction: 60-100°C for feeding, the reaction time is until all the formaldehyde aqueous solution is fed; the second temperature control reaction: 90-120°C for the synthesis reaction after feeding, the reaction time is 10-120 minutes.

7. The method for integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin according to claim 1, characterized in that The cooling temperature in step 2) should be 0~20℃.

8. The method for integrated recycling of the still residue produced during the synthesis of 5,5-dimethylhydantoin according to claim 1, characterized in that The total content of residual organic matter in the filtrate in step 3) is ≥ 10%.

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