Treatment process of dimethyl phosphite distillation residual liquid

Abstract

The invention discloses a treatment process of dimethyl phosphite distillation raffinate. The process comprises the following steps: filtering the dimethyl phosphite distillation raffinate; then putting the filtered filtrate into a container, and adding pure water; heating the container, dissolving the solution in the container until the solution is boiled, and stopping heating when no liquid drop is generated in a gas phase; cooling the solution in the container to 20-40 DEG C, and stopping cooling; adding liquid caustic soda into the solution in the container; transferring the solution in the container into a high-pressure kettle, and adding an efficient oxidant; heating the high-pressure kettle; introducing high-pressure air into the high-pressure kettle; controlling the reaction time in the high-pressure kettle to be 2-3 hours, stopping heating, and stopping introducing the high-pressure air; and cooling and crystallizing by using cooling water, centrifugally separating the crystal, and weighing to obtain the disodium hydrogen phosphate dodecahydrate. According to the method, the disodium hydrogen phosphate dodecahydrate can be prepared from the dimethyl phosphite distillation residual liquid, so that the waste liquid is well treated, the pollution is reduced, and the treatment thought of the dimethyl phosphite distillation residual liquid is widened.

Description

Technical Field

[0001] The invention relates to a treatment process for dimethyl phosphite distillation residue. Background Art

[0002] At present, dimethyl phosphite distillation residue is a byproduct of dimethyl phosphite production, which is the raw material of glyphosate production by glycine method. There are many ways to dispose of it. For example, Chinese patent with publication number CN112552341A discloses a glycine method for glyphosate synthesis, and another example is Chinese patent with publication number CN101928299A discloses a clean process for preparing high-purity glyphosate from glycine, and another example is Chinese patent with publication number CN102633241A discloses a method for recovering phosphorous acid by acid hydrolysis of dimethyl phosphite distillation residue; the above disposal processes are all based on the idea of ​​producing phosphorous acid and phosphoric acid, but in the case of unsatisfactory market conditions, the above ideas are single, which is not conducive to the sales of products. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a treatment process for dimethyl phosphite distillation residue. The process can prepare disodium hydrogen phosphate dodecahydrate by using the dimethyl phosphite distillation residue, thereby effectively treating the waste liquid, reducing pollution and broadening the treatment ideas for the dimethyl phosphite distillation residue.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a process for treating dimethyl phosphite distillation residue, the process steps include:

[0005] S01: filtering the dimethyl phosphite distillation residue;

[0006] S02: Then put the filtered filtrate into a container and add pure water;

[0007] S03: heating the container so that the solution in the container is dissolved until boiling, and stopping heating after no droplets are generated in the gas phase;

[0008] S04: Cooling the solution in the container to 20-40°C and stopping the cooling;

[0009] S05: adding liquid caustic soda to the solution in the container, and stopping adding liquid caustic soda when the pH value is controlled to be 7-9;

[0010] S06: moving the solution in the container into the autoclave and adding a high-efficiency oxidant;

[0011] S07: heating the autoclave; during the heating process, when the temperature reaches 120-150° C., introducing high-pressure air into the autoclave;

[0012] S08: When the temperature reaches 260°C and the pressure reaches 0.5Mpa, the gas in the autoclave is gradually discharged, and the temperature is controlled at 180-250°C and the pressure is controlled at 0.5-0.7Mpa;

[0013] S09: Under the control conditions in step S08, the reaction time in the autoclave is controlled to be 2 to 3 hours, and then the temperature is stopped and the high-pressure air is stopped;

[0014] S10: cooling the crystals with cooling water, centrifuging the crystals, and weighing to obtain disodium hydrogen phosphate dodecahydrate.

[0015] Further, in step S03, the temperature is controlled at 120°C to 130°C, and the heating time is controlled at 2 to 3 hours.

[0016] Furthermore, the dimethyl phosphite distillation residue is derived from a by-product in the process of producing dimethyl phosphite, a raw material of glyphosate, using the glycine method.

[0017] Furthermore, the components of the dimethyl phosphite distillation residue and the mass percentage of each component are: 5% to 10% of monoalkyl phosphite, 75% to 85% of phosphorous acid, 5% to 10% of dialkyl phosphite, and the others are inevitable impurities, totaling 100%.

[0018] Furthermore, in step S02, the weight of pure water added is 20% to 30% of the filtrate.

[0019] Furthermore, in step S03, the temperature is controlled at 120°C to 130°C, and the heating time is controlled at 2 to 3 hours.

[0020] Furthermore, the high-efficiency oxidant is a nitrate substance.

[0021] Further, step S01 specifically includes: weighing the dimethyl phosphite distillation residue and putting it into a tromethamine funnel to filter out impurities therein.

[0022] After adopting the above technical scheme, when the profit of producing phosphorous acid products by using dimethyl phosphite distillation residue is lower than the profit of producing disodium hydrogen phosphate dodecahydrate, the process line for preparing disodium hydrogen phosphate dodecahydrate is selected to improve the profit margin. DETAILED DESCRIPTION

[0023] The present invention provides a treatment process for dimethyl phosphite distillation residue, and those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It should be particularly pointed out that all similar replacements and modifications are obvious to those skilled in the art, and they all belong to the scope of protection of the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0024] A process for treating dimethyl phosphite distillation residue, the process steps comprising:

[0025] S01: filtering the dimethyl phosphite distillation residue; Step S01 specifically comprises: weighing the dimethyl phosphite distillation residue and putting it into a tromethamine funnel to filter out impurities therein; the impurities include tar, slag, etc., which are mainly brought over from yellow phosphorus and corrosion of pipelines during the production process.

[0026] S02: Then put the filtered filtrate into a container and add pure water;

[0027] S03: heating the container so that the solution in the container is dissolved until boiling, and stopping heating after no droplets are generated in the gas phase; this step mainly involves hydrolyzing the monoalkyl phosphite and dialkyl phosphite with water to generate phosphorous acid and methanol, which is gasified and cooled to a liquid under high temperature conditions with a content of about 80%, and is returned to the glyphosate production system for purification and used as a raw material for glyphosate production;

[0028] S04: Cooling the solution in the container to 20-40°C and stopping the cooling;

[0029] S05: adding liquid caustic soda to the solution in the container, and stopping adding liquid caustic soda when the pH value is controlled to be 7 to 9; in this step, the liquid caustic soda reacts with phosphorous acid to generate sodium phosphite;

[0030] S06: moving the solution in the container into the autoclave and adding a high-efficiency oxidant;

[0031] S07: heating the autoclave; during the heating process, when the temperature reaches 120-150° C., introducing high-pressure air into the autoclave;

[0032] S08: When the temperature reaches 260°C and the pressure reaches 0.5Mpa, the gas in the autoclave is gradually discharged, and the temperature is controlled at 180-250°C and the pressure is controlled at 0.5-0.7Mpa;

[0033] S09: Under the control conditions in step S08, the reaction time in the autoclave is controlled to be 2 to 3 hours, and then the temperature is stopped and the high-pressure air is stopped;

[0034] S10: cooling the crystals with cooling water, centrifuging the crystals, and weighing to obtain disodium hydrogen phosphate dodecahydrate.

[0035] Specifically, phosphorous acid contains organic matter such as COD and BOD, sodium phosphite is a strong reducing agent, and the high-efficiency oxidant is specifically nitrate. Nitrate is a strong oxidant. Under high temperature conditions and the introduction of oxygen, COD, BOD and other organic matter are oxidized and decomposed into CO2 and H2O, organic phosphorus is oxidized into phosphate, organic amines are decomposed into inorganic ammonia, and sodium phosphite is oxidized into phosphate.

[0036] Further, in step S03, the temperature is controlled at 120°C to 130°C, and the heating time is controlled at 2 to 3 hours.

[0037] Furthermore, the dimethyl phosphite distillation residue is derived from a by-product in the process of producing dimethyl phosphite, a raw material of glyphosate, using the glycine method.

[0038] Furthermore, the components of the dimethyl phosphite distillation residue and the mass percentage of each component are: 5% to 10% of monoalkyl phosphite, 75% to 85% of phosphorous acid, 5% to 10% of dialkyl phosphite, and the others are inevitable impurities, totaling 100%.

[0039] Furthermore, in step S02, the weight of pure water added is 20% to 30% of the filtrate.

[0040] Furthermore, in step S03, the temperature is controlled at 120°C to 130°C, and the heating time is controlled at 2 to 3 hours.

[0041] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments.

[0042] Embodiment 1

[0043] A process for treating dimethyl phosphite distillation residue, the process steps comprising:

[0044] S01: Weigh 250g of dimethyl phosphite distillation residue and put it into a chloramine funnel to filter out impurities; after testing, the components of the dimethyl phosphite distillation residue and the mass percentage of each component are: monoalkyl phosphite 6.3%, phosphorous acid 82.4%, dialkyl phosphite 9.6%, and the others are inevitable impurities, totaling 250g;

[0045] S02: Then put the filtered filtrate into a container and add 57.5g of pure water;

[0046] S03: heating the container so that the solution in the container is dissolved until boiling, the temperature is controlled at 121°C, and after heating for 2.2 hours, no droplets are generated in the gas phase, and the heating is stopped, and the container is loaded to obtain;

[0047] S04: Cool the solution in the container to 25°C and stop cooling;

[0048] S05: Add 1173.5 g of liquid caustic soda with a concentration of 30% into the solution in the container, and stop adding liquid caustic soda when the pH value is controlled to be 7.5;

[0049] S06: Move the solution in the container into an autoclave and add 5.2 g of nitrate;

[0050] S07: heating the autoclave; during the heating process, when the temperature reaches 125° C., introducing high-pressure air into the autoclave;

[0051] S08: When the temperature reaches 260°C and the pressure reaches 0.5Mpa, the gas in the autoclave is gradually discharged, and the temperature is controlled at 195°C and the pressure is controlled at 0.55Mpa;

[0052] S09: Under the control conditions in step S08, the reaction time in the autoclave is controlled to be 2.3 hours, and then the temperature is stopped and the high-pressure air is stopped;

[0053] S10: Then cool the crystals with cooling water, centrifuge the crystals, and weigh to obtain 952.6 g of disodium hydrogen phosphate dodecahydrate.

[0054] Embodiment 2

[0055] A process for treating dimethyl phosphite distillation residue, the process steps comprising:

[0056] S01: Weigh 250g of dimethyl phosphite distillation residue and put it into a chloramine funnel to filter out impurities; after testing, the components of the dimethyl phosphate distillation residue and the mass percentage of each component are: monoalkyl phosphite 7.6%, phosphorous acid 77.6%, dialkyl phosphite 8.4%, and the remainder is inevitable impurities, totaling 250g;

[0057] S02: Then put the filtered filtrate into a container and add 65g of pure water;

[0058] S03: heating the container so that the solution in the container is dissolved until boiling, the temperature is controlled at 125° C., the heating time is controlled at 2.5 h, and the heating is stopped after no droplets are generated in the gas phase;

[0059] S04: Cool the solution in the container to 25°C and stop cooling;

[0060] S05: Add 1252 g of liquid caustic soda with a concentration of 30% into the solution in the container, and stop adding liquid caustic soda when the pH value is controlled to be 8.4;

[0061] S06: Move the solution in the container into an autoclave and add 4.5 g of nitrate;

[0062] S07: heating the autoclave; during the heating process, when the temperature reaches 135° C., introducing high-pressure air into the autoclave;

[0063] S08: When the temperature reaches 260°C and the pressure reaches 0.5Mpa, the gas in the autoclave is gradually discharged, and the temperature is controlled at 205°C and the pressure is controlled at 0.62Mpa;

[0064] S09: Under the control conditions in step S08, the reaction time in the autoclave is controlled to be 2.5 hours, and then the temperature is stopped and the high-pressure air is stopped;

[0065] S10: Then cool the crystals with cooling water, centrifuge the crystals, and weigh to obtain 921.5% disodium hydrogen phosphate dodecahydrate.

[0066] Embodiment 3

[0067] A process for treating dimethyl phosphite distillation residue, the process steps comprising:

[0068] S01: Weigh 250g of dimethyl phosphite distillation residue and put it into a chloramine funnel to filter out impurities; after testing, the components of the dimethyl phosphate distillation residue and the mass percentage of each component are: monoalkyl phosphite 8.2%, phosphorous acid 74.5%, dialkyl phosphite 6.6%, and the remainder is inevitable impurities, totaling 250g;

[0069] S02: Then put the filtered filtrate into a container and add 70g of pure water;

[0070] S03: heating the container so that the solution in the container is dissolved until boiling, the temperature is controlled at 127° C., the heating time is controlled at 2.8 h, and the heating is stopped after no droplets are generated in the gas phase;

[0071] S04: Cool the solution in the container to 35°C and stop cooling;

[0072] S05: Add 1273 g of liquid caustic soda with a concentration of 30% into the solution in the container, and stop adding liquid caustic soda when the pH value is controlled to be 8.9;

[0073] S06: Move the solution in the container into an autoclave and add 6.2 g of nitrate;

[0074] S07: heating the autoclave; during the heating process, when the temperature reaches 146° C., introducing high-pressure air into the autoclave;

[0075] S08: When the temperature reaches 260°C and the pressure reaches 0.5Mpa, the gas in the autoclave is gradually discharged, and the temperature is controlled at 241°C and the pressure is controlled at 0.66Mpa;

[0076] S09: Under the control conditions in step S08, the reaction time in the autoclave is controlled to be 2.8 hours, and then the temperature is stopped and the high-pressure air is stopped;

[0077] S10: Then cool the crystals with cooling water, centrifuge the crystals, and weigh to obtain 896.5 sodium hydrogen phosphate dodecahydrate.

[0078] It can be seen from the above examples that disodium hydrogen phosphate dodecahydrate can be prepared using dimethyl phosphite distillation residue, thereby replacing the method of preparing phosphorous acid.

[0079] The specific embodiments described above further illustrate the technical problems, technical solutions and beneficial effects solved by the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for treating dimethyl phosphite distillation residue, characterized in that: The process steps include: S01: filtering the dimethyl phosphite distillation residue; S02: Then put the filtered filtrate into a container and add pure water; S03: heating the container so that the solution in the container is dissolved until boiling, and stopping heating after no droplets are generated in the gas phase; S04: Cooling the solution in the container to 20-40°C and stopping the cooling; S05: adding liquid caustic soda to the solution in the container, and stopping adding liquid caustic soda when the pH value is controlled to be 7-9; S06: moving the solution in the container into the autoclave and adding a high-efficiency oxidant; S07: heating the autoclave; during the heating process, when the temperature reaches 120-150° C., introducing high-pressure air into the autoclave; S08: When the temperature reaches 260°C and the pressure reaches 0.5Mpa, the gas in the autoclave is gradually discharged, and the temperature is controlled at 180-250°C and the pressure is controlled at 0.5-0.7Mpa; S09: Under the control conditions in step S08, the reaction time in the autoclave is controlled to be 2 to 3 hours, and then the temperature is stopped and the high-pressure air is stopped; S10: cooling the crystals with cooling water, centrifuging the crystals, and weighing to obtain disodium hydrogen phosphate dodecahydrate.

2. The treatment process according to claim 1, characterized in that: In step S03, the temperature is controlled at 120°C to 130°C, and the heating time is controlled at 2 to 3 hours.

3. The treatment process according to claim 1, characterized in that: The dimethyl phosphite distillation residue is derived from a by-product in the process of producing dimethyl phosphite, a raw material of glyphosate, by the glycine method.

4. The treatment process according to claim 1, characterized in that: The components of the dimethyl phosphite distillation residue and the mass percentage of each component are: 5% to 10% of monoalkyl phosphite, 75% to 85% of phosphorous acid, 5% to 10% of dialkyl phosphite, and the rest are inevitable impurities, totaling 100%.

5. The treatment process according to claim 1, characterized in that: In step S02, the weight of pure water added is 20% to 30% of the filtrate.

6. The treatment process according to claim 1, characterized in that: In step S03, the temperature is controlled at 120°C to 130°C, and the heating time is controlled at 2 to 3 hours.

7. The treatment process according to claim 1, characterized in that: The highly efficient oxidant is a nitrate substance.

8. The treatment process according to claim 1, characterized in that: Step S01 specifically comprises: weighing the dimethyl phosphite distillation residue and putting it into a tromethamine funnel to filter out the impurities therein.