A clean production method for co-producing phosphorous acid with ethyl chloride

Abstract

The invention discloses a clean production method for co-producing phosphorous acid with ethyl chloride, wherein phosphorus trichloride is mixed with a hydrochloric acid solution for hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride; the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid; a catalyst is filled in a reaction tower, and the gaseous hydrogen chloride is mixed with gasified ethanol and then introduced into the reaction tower for reaction to obtain ethyl chloride. The invention has a simple process, realizes the co-production of phosphorous acid with ethyl chloride, has low requirements for reaction temperature and reaction time, and has good prospects for promotion and application.

Description

Technical Field

[0001] The present invention relates to a clean production method for co-producing phosphorous acid with ethyl chloride, belonging to the technical field of chemical production. Background Art

[0002] Ethyl chloride is a colorless liquid below 12.4°C. It is a widely used organic solvent and is also widely used in the synthesis of pesticides, dyes, medicines and their intermediates. The synthesis methods of ethyl chloride mainly include the following three methods:

[0003] 1. Ethylene and hydrogen chloride addition reaction method. The raw material ethylene has high requirements for equipment conditions for transportation and storage, and requires high temperature and high pressure to react. The reaction conditions are harsh, so industrialization is limited.

[0004] 2. Ethane chlorination method. The reaction conditions are mild, but there are many by-products. When producing ethyl chloride, a large amount of ethylene dichloride and trichloroethane are also generated, which leads to complex product purification and separation processes, low product yields, and is not suitable for industrial mass production.

[0005] 3. Synthesis method of ethanol and hydrochloric acid. The operation is simple, enamel equipment is used, the reaction conditions are mild, and high-purity ethyl chloride can be obtained after refining. This method has the advantages of high product purity and stable yield.

[0006] The third method mentioned above is the main process for producing ethyl chloride at present, but this method also has obvious defects:

[0007] 1. The prices of raw materials hydrochloric acid and ethanol are relatively high, and the raw material cost is high.

[0008] 2. The ethanol conversion rate is low, and part of the ethanol will be brought into the crude ethyl chloride and enter the post-processing refining process together.

[0009] 3. Use hydrochloric acid to participate in the reaction. A large amount of water is brought into the reaction system. At the same time, the reaction produces water. All of this water needs to be evaporated from the reaction system. This part of water contains 5-10% ethanol and 10-20% hydrogen chloride, which needs further distillation.

[0010] 4. Using hydrochloric acid to participate in the reaction makes the reaction system unstable and cannot achieve continuous production.

[0011] 5. It is mainly based on batch reaction, which is complicated to operate and has low production efficiency.

[0012] Patent application CN110283045A discloses a clean production method for co-producing phosphorous acid with ethyl chloride, wherein phosphorus trichloride and hydrochloric acid are first hydrolyzed to generate hydrogen chloride gas and phosphorous acid solution; the phosphorous acid solution generated by the hydrolysis is vacuum concentrated and crystallized and then centrifuged to obtain the finished phosphorous acid, the filtrate is recycled and crystallized and reused, and the condensate is used as a phosphorus washing liquid for phosphorus washing; the hydrogen chloride generated by the hydrolysis is first purified by phosphorus washing to remove the entrained phosphorus trichloride, then cooled to remove water, and then mixed with vaporized ethanol and passed into a reactor to perform a synthetic reaction to generate ethyl chloride and water; the mixed gas phase generated by the reaction is first condensed by a condenser, a part of the condensate is refluxed to the reactor, and the other part is refluxed to the last stage of phosphorus washing kettle; the condensed crude ethyl chloride gas is then washed with water, washed with alkali, dried at 2-4 levels, and then compressed and condensed to obtain the finished liquefied ethyl chloride. This patent application realizes the co-production of phosphorous acid with ethyl chloride, but requires multi-stage reactions, the process steps are cumbersome, and the hydrogen chloride is excessive, which affects the purity of the product and limits the industrial production application. Summary of the invention

[0013] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a clean production method for co-producing phosphorous acid with ethyl chloride, which has a simple process and realizes the co-production of phosphorous acid with ethyl chloride.

[0014] To achieve the above object, the present invention adopts the following technical solutions:

[0015] A clean production method for co-producing phosphorous acid with ethyl chloride, the specific steps are as follows:

[0016] (1) first preparing a carrier with activated carbon as a core and amorphous alumina as a shell, then uniformly dispersing zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide in anhydrous ethanol to obtain a zinc chloride solution, and then compounding the carrier with the zinc chloride solution to obtain a catalyst for standby use;

[0017] (2) then mixing phosphorus trichloride with hydrochloric acid solution to carry out hydrolysis reaction to generate phosphorous acid solution and gaseous hydrogen chloride, which are respectively entered into step (3) and step (4);

[0018] (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid;

[0019] (4) A catalyst is filled in a reaction tower, and gaseous hydrogen chloride is mixed with vaporized ethanol and introduced into the reaction tower for reaction to obtain ethyl chloride.

[0020] Preferably, in step (1), the carrier is prepared by the following method, measured in parts by weight: first, ultrasonically disperse 1 part of powdered activated carbon in 4-5 parts of 1-2% glucose aqueous solution to obtain activated carbon slurry; then, add 1 part of aluminum chloride to 8-10 parts of distilled water, stir at 50-60°C for 15-25 minutes, add activated carbon slurry while stirring, add 8-10% ammonia water dropwise under heat-insulating stirring conditions until the system pH = 8, keep warm and stand for 1-2 hours, filter and take the filter cake, wash with water until there is no chloride ion, dry at 110-120°C for 10-12 hours, roast at 550-600°C for 6-8 hours under nitrogen protection, and crush to 100-200 mesh to obtain the carrier.

[0021] Further preferably, the process conditions of ultrasonic dispersion are: 400-500W ultrasonic oscillation treatment for 20-30 minutes; stirring rate is 300-500r / min.

[0022] Preferably, in step (1), the mass ratio of zinc chloride to anhydrous ethanol is 1:7-9, and the molar amounts of zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide are equimolar; ultrasonic dispersion is adopted, and the specific process conditions are: 500-600W ultrasonic oscillation treatment for 20-30 minutes.

[0023] Preferably, in step (1), the specific method of compounding is: adding the carrier to a zinc chloride solution of 11 to 14 times its weight, stirring at room temperature (25°C) for 4 to 5 hours, heating in a water bath at 70 to 80°C for 6 to 7 hours under closed conditions, keeping it open at 70 to 80°C for 6 to 7 hours, and vacuum drying at 70 to 80°C for 6 to 7 hours.

[0024] Preferably, in step (2), a hydrochloric acid solution is injected into a reaction vessel, and phosphorus trichloride is added dropwise at 65 to 70° C. and 0.05 to 0.08 MPa to carry out a bubbling hydrolysis reaction for 90 to 110 minutes; wherein the mass concentration of the hydrochloric acid solution is 30 to 36%, and the volume ratio of phosphorus trichloride to the hydrochloric acid solution is 1:3.

[0025] Preferably, in step (3), the preparation method of phosphorous acid is as follows: the phosphorous acid solution is concentrated at 75 to 85°C and -0.05 to -0.07 MPa for 80 to 100 minutes, transferred to a crystallization kettle, cooled to 35 to 40°C at 20 to 30°C / hour, cooled to room temperature (25°C) at 2 to 3°C / hour, and centrifuged to dehydrate to obtain phosphorous acid.

[0026] Further preferably, the process conditions for centrifugal dehydration are: centrifugation at 15000-20000 r / min for 10-15 minutes.

[0027] Preferably, in step (4), the dimensions of the reaction tower are: 0.46 m in diameter and 4.6 m in height; the filling amount of the catalyst is 3 / 5 to 4 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 2 to 3 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts. The introduction rate of gaseous hydrogen chloride and vaporized ethanol is critical. If it is too fast, the reaction will be insufficient, and the product yield and purity will be reduced; if it is too slow, impurities may be generated, affecting the purity of the product, and the long reaction time also increases the production cost.

[0028] Preferably, in step (4), the reaction temperature in the reaction tower is 35-40°C.

[0029] Preferably, in step (4), the product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -3 to -5°C at a rate of 1 to 2°C / min while stirring, and the liquid is filtered out at this temperature and dried to obtain ethyl chloride.

[0030] Further preferably, the gas phase pressure in the condenser is 0.8 MPa and the outlet temperature of the cooling circulating water is below 38°C.

[0031] Preferably, the stirring rate is 200 to 300 r / min. If the stirring rate is too slow, ethyl chloride will be introduced into the process of water freezing into ice, resulting in ethyl chloride loss; if the stirring rate is too fast, it will affect the freezing of water into ice and affect the separation of ethyl chloride and water.

[0032] Further preferably, the specific method of drying is: the liquid flows through a cylindrical adsorption device filled with calcium chloride, the diameter of the adsorption device is 0.6m, the height is 1.5m, and the liquid flow rate is 300kg / h.

[0033] Beneficial effects of the present invention:

[0034] The present invention mixes phosphorus trichloride with a hydrochloric acid solution for hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride; the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid; a catalyst is filled in a reaction tower, and the gaseous hydrogen chloride is mixed with gasified ethanol and then introduced into the reaction tower for reaction to obtain ethyl chloride. The present invention has a simple process, realizes the co-production of phosphorous acid with ethyl chloride, has low requirements for reaction temperature and reaction time, and has good prospects for promotion and application.

[0035] Phosphorus trichloride and hydrochloric acid solution are mixed and hydrolyzed to generate a phosphorous acid solution containing a small amount of hydrochloric acid, which will affect the purity of the phosphorous acid product. The present invention achieves the removal of hydrochloric acid during concentration and improves the purity of phosphorous acid by adjusting the vacuum concentration crystallization parameters.

[0036] A specially prepared catalyst is introduced when gaseous hydrogen chloride reacts with gasified ethanol. First, a carrier with activated carbon as the core and amorphous alumina as the shell is prepared. Then zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide salt are uniformly dispersed in anhydrous ethanol to obtain a zinc chloride solution, and then the carrier and the zinc chloride solution are compounded to obtain. The catalyst promotes full contact between gaseous hydrogen chloride and ethanol, promotes the reaction, and has low requirements for reaction temperature and reaction time, so that a complete reaction can be achieved. Excessive hydrogen chloride is not required, which saves raw materials and reduces the difficulty of post-processing. When preparing the catalyst, 1-ethyl-3-methylimidazolium dicyanamide salt has a certain complexing effect on zinc ions, strengthens the binding force between zinc chloride and the carrier, and thus exerts a better catalytic effect. The carrier is activated carbon as the core and amorphous alumina as the shell, wherein the amorphous alumina also synergizes with zinc ions to improve the catalytic effect.

[0037] After the reaction is completed, the product discharged from the top of the reaction tower is condensed by a condenser, and water is condensed under cooling conditions to achieve separation of ethyl chloride and water. This is simple and convenient, and ensures the yield and purity of ethyl chloride. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its contents.

[0039] Powdered activated carbon was purchased from Hunan Durban Activated Carbon Co., Ltd. with a particle size of 100 mesh.

[0040] 1-Ethyl-3-methylimidazolium dicyanamide was purchased from Henan Wokas Biotechnology Co., Ltd.

[0041] Embodiment 1:

[0042] A clean production method for co-producing phosphorous acid with ethyl chloride, the specific steps are as follows:

[0043] (1) first preparing a carrier with activated carbon as the core and amorphous alumina as the shell, then uniformly dispersing 1 kg of zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide in 7 kg of anhydrous ethanol to obtain a zinc chloride solution, and then compounding the carrier with 11 times the weight of the zinc chloride solution to obtain a catalyst for standby use;

[0044] (2) then mixing phosphorus trichloride with a 30% hydrochloric acid solution by volume three times the volume thereof to carry out a hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride, which are then respectively carried out into step (3) and step (4);

[0045] (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid;

[0046] (4) A catalyst is filled in a reaction tower, and gaseous hydrogen chloride is mixed with vaporized ethanol and introduced into the reaction tower for reaction to obtain ethyl chloride.

[0047] Wherein, in step (1), the carrier is prepared by the following method: first, ultrasonically disperse 1 kg of powdered activated carbon in 4 kg of 1% glucose aqueous solution to obtain activated carbon slurry; then, add 1 kg of aluminum chloride to 8 kg of distilled water, stir at 50°C for 15 minutes, add activated carbon slurry while stirring, add 8% ammonia water dropwise under heat preservation and stirring conditions until the system pH = 8, keep warm and stand for 1 hour, filter and take the filter cake, wash with water until there is no chloride ion, dry at 110°C for 10 hours, roast at 550°C for 6 hours under nitrogen protection, and crush to 100 mesh to obtain the carrier.

[0048] The process conditions of ultrasonic dispersion are: 400W ultrasonic oscillation treatment for 20 minutes; stirring rate is 300r / min.

[0049] In step (1), zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide are used in equimolar amounts; ultrasonic dispersion is adopted, and the specific process conditions are: 500W ultrasonic oscillation treatment for 20 minutes.

[0050] In step (1), the specific method of compounding is: adding the carrier to the zinc chloride solution, stirring at room temperature (25°C) for 4 hours, heating in a 70°C water bath for 6 hours under closed conditions, keeping it open at 70°C for 6 hours, and vacuum drying at 70°C for 6 hours.

[0051] In step (2), hydrochloric acid solution is injected into the reaction container, and phosphorus trichloride is added dropwise at 65° C. and 0.05 MPa to carry out bubbling hydrolysis reaction for 90 minutes.

[0052] In step (3), the preparation method of phosphorous acid is as follows: the phosphorous acid solution is concentrated at 75°C and -0.05MPa for 80 minutes, transferred to a crystallization kettle, cooled to 35°C at 20°C / hour, cooled to room temperature (25°C) at 2°C / hour, and centrifuged to obtain phosphorous acid. The process conditions of centrifugal dehydration are: centrifugation at 15000r / min for 10 minutes.

[0053] In step (4), the dimensions of the reaction tower are: diameter 0.46 m, height 4.6 m; the filling amount of the catalyst is 3 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 2 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts.

[0054] The reaction temperature in the reaction tower is 35°C.

[0055] The product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -3°C at a rate of 1°C / min while stirring. At this temperature, the liquid is filtered and dried to obtain ethyl chloride. The gas phase pressure in the condenser is 0.8MPa, and the outlet temperature of the cooling circulating water is below 38°C.

[0056] The stirring rate is 200r / min.

[0057] The specific method of drying is: the liquid flows through a cylindrical adsorption device filled with calcium chloride, the diameter of the adsorption device is 0.6m, the height is 1.5m, and the liquid flow rate is 300kg / h.

[0058] Embodiment 2:

[0059] A clean production method for co-producing phosphorous acid with ethyl chloride, the specific steps are as follows:

[0060] (1) first preparing a carrier with activated carbon as the core and amorphous alumina as the shell, then uniformly dispersing 1 kg of zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide in 9 kg of anhydrous ethanol to obtain a zinc chloride solution, and then compounding the carrier with 14 times the weight of the zinc chloride solution to obtain a catalyst for standby use;

[0061] (2) then mixing phosphorus trichloride with a 36% hydrochloric acid solution by volume, and performing a hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride, which are then respectively subjected to step (3) and step (4);

[0062] (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid;

[0063] (4) A catalyst is filled in a reaction tower, and gaseous hydrogen chloride is mixed with vaporized ethanol and introduced into the reaction tower for reaction to obtain ethyl chloride.

[0064] Wherein, in step (1), the carrier is prepared by the following method: first, ultrasonically disperse 1 kg of powdered activated carbon in 5 kg of 2% glucose aqueous solution to obtain activated carbon slurry; then, add 1 kg of aluminum chloride to 10 kg of distilled water, stir at 60°C for 25 minutes, add activated carbon slurry while stirring, add 10% ammonia water dropwise under heat preservation and stirring conditions until the system pH = 8, keep warm and stand for 2 hours, filter and take the filter cake, wash with water until there is no chloride ion, dry at 120°C for 12 hours, roast at 600°C for 8 hours under nitrogen protection, and crush to 200 mesh to obtain the carrier.

[0065] The process conditions of ultrasonic dispersion are: 500W ultrasonic oscillation treatment for 30 minutes; stirring rate is 500r / min.

[0066] In step (1), zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide are used in equimolar amounts; ultrasonic dispersion is adopted, and the specific process conditions are: 600W ultrasonic oscillation treatment for 30 minutes.

[0067] In step (1), the specific method of compounding is: adding the carrier to the zinc chloride solution, stirring at room temperature (25°C) for 5 hours, heating in a water bath at 80°C for 7 hours under closed conditions, keeping it open at 80°C for 7 hours, and vacuum drying at 80°C for 7 hours.

[0068] In step (2), hydrochloric acid solution is injected into the reaction container, and phosphorus trichloride is added dropwise at 70° C. and 0.08 MPa to carry out bubbling hydrolysis reaction for 110 minutes.

[0069] In step (3), the preparation method of phosphorous acid is as follows: the phosphorous acid solution is concentrated at 85°C and -0.07MPa for 100 minutes, transferred to a crystallization kettle, cooled to 40°C at 30°C / hour, cooled to room temperature (25°C) at 3°C / hour, and centrifuged to obtain phosphorous acid. The process conditions of centrifugal dehydration are: centrifugation at 20000r / min for 15 minutes.

[0070] In step (4), the dimensions of the reaction tower are: diameter 0.46 m, height 4.6 m; the filling amount of the catalyst is 4 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 3 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts.

[0071] The reaction temperature in the reaction tower is 40°C.

[0072] The product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -5°C at a rate of 2°C / min while stirring. At this temperature, the liquid is filtered and dried to obtain ethyl chloride. The gas phase pressure in the condenser is 0.8MPa, and the outlet temperature of the cooling circulating water is below 38°C.

[0073] The stirring rate is 300r / min.

[0074] The specific method of drying is: the liquid flows through a cylindrical adsorption device filled with calcium chloride, the diameter of the adsorption device is 0.6m, the height is 1.5m, and the liquid flow rate is 300kg / h.

[0075] Embodiment 3:

[0076] A clean production method for co-producing phosphorous acid with ethyl chloride, the specific steps are as follows:

[0077] (1) first preparing a carrier with activated carbon as the core and amorphous alumina as the shell, then uniformly dispersing 1 kg of zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide in 7 kg of anhydrous ethanol to obtain a zinc chloride solution, and then compounding the carrier with 14 times the weight of the zinc chloride solution to obtain a catalyst for standby use;

[0078] (2) then mixing phosphorus trichloride with a 30% hydrochloric acid solution by volume three times the volume thereof to carry out a hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride, which are then respectively carried out into step (3) and step (4);

[0079] (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid;

[0080] (4) A catalyst is filled in a reaction tower, and gaseous hydrogen chloride is mixed with vaporized ethanol and introduced into the reaction tower for reaction to obtain ethyl chloride.

[0081] Wherein, in step (1), the carrier is prepared by the following method: first, ultrasonically disperse 1 kg of powdered activated carbon in 5 kg of 1% glucose aqueous solution to obtain activated carbon slurry; then, add 1 kg of aluminum chloride to 10 kg of distilled water, stir at 50°C for 25 minutes, add activated carbon slurry while stirring, add 8% ammonia water dropwise under heat preservation and stirring conditions until the system pH = 8, keep warm and stand for 2 hours, filter and take the filter cake, wash with water until there is no chloride ion, dry at 110°C for 12 hours, roast at 550°C for 8 hours under nitrogen protection, and crush to 100 mesh to obtain the carrier.

[0082] The process conditions of ultrasonic dispersion are: 500W ultrasonic oscillation treatment for 20 minutes; stirring rate is 500r / min.

[0083] In step (1), zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide are used in equimolar amounts; ultrasonic dispersion is adopted, and the specific process conditions are: 500W ultrasonic oscillation treatment for 30 minutes.

[0084] In step (1), the specific method of compounding is: adding the carrier to the zinc chloride solution, stirring at room temperature (25°C) for 4 hours, heating in a water bath at 80°C for 6 hours under closed conditions, keeping it open at 80°C for 6 hours, and vacuum drying at 80°C for 6 hours.

[0085] In step (2), hydrochloric acid solution is injected into a reaction vessel, and phosphorus trichloride is added dropwise at 70° C. and 0.05 MPa to carry out a bubbling hydrolysis reaction for 110 minutes.

[0086] In step (3), the preparation method of phosphorous acid is as follows: the phosphorous acid solution is concentrated at 75°C and -0.07MPa for 80 minutes, transferred to a crystallization kettle, cooled to 35°C at 30°C / hour, cooled to room temperature (25°C) at 3°C / hour, and centrifuged to obtain phosphorous acid. The process conditions of centrifugal dehydration are: centrifugation at 15000r / min for 15 minutes.

[0087] In step (4), the dimensions of the reaction tower are: diameter 0.46 m, height 4.6 m; the filling amount of the catalyst is 3 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 3 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts.

[0088] The reaction temperature in the reaction tower is 35°C.

[0089] The product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -3°C at a rate of 2°C / min while stirring. At this temperature, the liquid is filtered and dried to obtain ethyl chloride. The gas phase pressure in the condenser is 0.8MPa, and the outlet temperature of the cooling circulating water is below 38°C.

[0090] The stirring rate is 300r / min.

[0091] The specific method of drying is: the liquid flows through a cylindrical adsorption device filled with calcium chloride, the diameter of the adsorption device is 0.6m, the height is 1.5m, and the liquid flow rate is 300kg / h.

[0092] Embodiment 4:

[0093] A clean production method for co-producing phosphorous acid with ethyl chloride, the specific steps are as follows:

[0094] (1) first preparing a carrier with activated carbon as the core and amorphous alumina as the shell, then uniformly dispersing 1 kg of zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide in 8 kg of anhydrous ethanol to obtain a zinc chloride solution, and then compounding the carrier with 12 times the weight of the zinc chloride solution to obtain a catalyst for standby use;

[0095] (2) then mixing phosphorus trichloride with a 33% hydrochloric acid solution by volume, and performing a hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride, which are then respectively subjected to step (3) and step (4);

[0096] (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid;

[0097] (4) A catalyst is filled in a reaction tower, and gaseous hydrogen chloride is mixed with vaporized ethanol and introduced into the reaction tower for reaction to obtain ethyl chloride.

[0098] Wherein, in step (1), the carrier is prepared by the following method: first, ultrasonically disperse 1 kg of powdered activated carbon in 4.5 kg of 2% glucose aqueous solution to obtain activated carbon slurry; then, add 1 kg of aluminum chloride to 9 kg of distilled water, stir at 55°C for 20 minutes, add activated carbon slurry while stirring, add 10% ammonia water dropwise under heat-insulating and stirring conditions until the system pH = 8, keep warm and stand for 2 hours, filter and take the filter cake, wash with water until there is no chloride ion, dry at 115°C for 11 hours, roast at 580°C for 7 hours under nitrogen protection, and crush to 150 mesh to obtain the carrier.

[0099] The process conditions of ultrasonic dispersion are: 500W ultrasonic oscillation treatment for 25 minutes; stirring rate is 400r / min.

[0100] In step (1), zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide are used in equimolar amounts; ultrasonic dispersion is adopted, and the specific process conditions are: 600W ultrasonic oscillation treatment for 25 minutes.

[0101] In step (1), the specific method of compounding is: adding the carrier to the zinc chloride solution, stirring at room temperature (25°C) for 4.5 hours, heating in a water bath at 75°C for 6.5 hours under closed conditions, keeping it at 75°C for 7 hours, and vacuum drying at 75°C for 7 hours.

[0102] In step (2), hydrochloric acid solution is injected into the reaction container, and phosphorus trichloride is added dropwise at 68° C. and 0.07 MPa to carry out bubbling hydrolysis reaction for 100 minutes.

[0103] In step (3), the preparation method of phosphorous acid is as follows: the phosphorous acid solution is concentrated at 80°C and -0.06MPa for 90 minutes, transferred to a crystallization kettle, cooled to 37°C at 25°C / hour, cooled to room temperature (25°C) at 2.5°C / hour, and centrifuged to obtain phosphorous acid. The process conditions of centrifugal dehydration are: centrifugation at 18000r / min for 12 minutes.

[0104] In step (4), the dimensions of the reaction tower are: diameter 0.46 m, height 4.6 m; the filling amount of the catalyst is 3 / 5 to 4 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 2.5 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts.

[0105] The reaction temperature in the reaction tower is 38°C.

[0106] The product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -4°C at a rate of 1.5°C / min while stirring. The liquid is filtered and dried at this temperature to obtain ethyl chloride. The gas phase pressure in the condenser is 0.8MPa, and the outlet temperature of the cooling circulating water is below 38°C.

[0107] The stirring rate is 250r / min.

[0108] The specific method of drying is: the liquid flows through a cylindrical adsorption device filled with calcium chloride, the diameter of the adsorption device is 0.6m, the height is 1.5m, and the liquid flow rate is 300kg / h.

[0109] Comparative Example 1

[0110] A method for producing phosphorous acid by co-production of ethyl chloride, comprising the following specific steps:

[0111] (1) Powdered activated carbon is used as a carrier, and then 1 kg of zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide are uniformly dispersed in 7 kg of anhydrous ethanol to obtain a zinc chloride solution, and then the carrier is compounded with 11 times the weight of the zinc chloride solution to obtain a catalyst for standby use;

[0112] (2) then mixing phosphorus trichloride with a 30% hydrochloric acid solution by volume three times the volume thereof to carry out a hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride, which are then respectively carried out into step (3) and step (4);

[0113] (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid;

[0114] (4) A catalyst is filled in a reaction tower, and gaseous hydrogen chloride is mixed with vaporized ethanol and introduced into the reaction tower for reaction to obtain ethyl chloride.

[0115] Wherein, in step (1), zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide salt are used in equimolar amounts; ultrasonic dispersion is adopted, and the specific process conditions are: 500W ultrasonic oscillation treatment for 20 minutes.

[0116] In step (1), the specific method of compounding is: adding the carrier to the zinc chloride solution, stirring at room temperature (25°C) for 4 hours, heating in a 70°C water bath for 6 hours under closed conditions, keeping it open at 70°C for 6 hours, and vacuum drying at 70°C for 6 hours.

[0117] In step (2), hydrochloric acid solution is injected into the reaction container, and phosphorus trichloride is added dropwise at 65° C. and 0.05 MPa to carry out bubbling hydrolysis reaction for 90 minutes.

[0118] In step (3), the preparation method of phosphorous acid is as follows: the phosphorous acid solution is concentrated at 75°C and -0.05MPa for 80 minutes, transferred to a crystallization kettle, cooled to 35°C at 20°C / hour, cooled to room temperature (25°C) at 2°C / hour, and centrifuged to obtain phosphorous acid. The process conditions of centrifugal dehydration are: centrifugation at 15000r / min for 10 minutes.

[0119] In step (4), the dimensions of the reaction tower are: diameter 0.46 m, height 4.6 m; the filling amount of the catalyst is 3 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 2 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts.

[0120] The reaction temperature in the reaction tower is 35°C.

[0121] The product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -3°C at a rate of 1°C / min while stirring. At this temperature, the liquid is filtered and dried to obtain ethyl chloride. The gas phase pressure in the condenser is 0.8MPa, and the outlet temperature of the cooling circulating water is below 38°C.

[0122] The stirring rate is 200r / min.

[0123] The specific method of drying is: the liquid flows through a cylindrical adsorption device filled with calcium chloride, the diameter of the adsorption device is 0.6m, the height is 1.5m, and the liquid flow rate is 300kg / h.

[0124] Comparative Example 2

[0125] A method for producing phosphorous acid by co-production of ethyl chloride, comprising the following specific steps:

[0126] (1) first preparing a carrier with activated carbon as the core and amorphous alumina as the shell, then uniformly dispersing 1 kg of zinc chloride in 7 kg of anhydrous ethanol to obtain a zinc chloride solution, and then compounding the carrier with 11 times the weight of the zinc chloride solution to obtain a catalyst for standby use;

[0127] (2) then mixing phosphorus trichloride with a 30% hydrochloric acid solution by volume three times the volume thereof to carry out a hydrolysis reaction to generate a phosphorous acid solution and gaseous hydrogen chloride, which are then respectively carried out into step (3) and step (4);

[0128] (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid;

[0129] (4) A catalyst is filled in a reaction tower, and gaseous hydrogen chloride is mixed with vaporized ethanol and introduced into the reaction tower for reaction to obtain ethyl chloride.

[0130] Wherein, in step (1), the carrier is prepared by the following method: first, ultrasonically disperse 1 kg of powdered activated carbon in 4 kg of 1% glucose aqueous solution to obtain activated carbon slurry; then, add 1 kg of aluminum chloride to 8 kg of distilled water, stir at 50°C for 15 minutes, add activated carbon slurry while stirring, add 8% ammonia water dropwise under heat preservation and stirring conditions until the system pH = 8, keep warm and stand for 1 hour, filter and take the filter cake, wash with water until there is no chloride ion, dry at 110°C for 10 hours, roast at 550°C for 6 hours under nitrogen protection, and crush to 100 mesh to obtain the carrier.

[0131] The process conditions of ultrasonic dispersion are: 400W ultrasonic oscillation treatment for 20 minutes; stirring rate is 300r / min.

[0132] In step (1), ultrasonic dispersion is adopted, and the specific process conditions are: 500W ultrasonic oscillation treatment for 20 minutes.

[0133] In step (1), the specific method of compounding is: adding the carrier to the zinc chloride solution, stirring at room temperature (25°C) for 4 hours, heating in a 70°C water bath for 6 hours under closed conditions, keeping it open at 70°C for 6 hours, and vacuum drying at 70°C for 6 hours.

[0134] In step (2), hydrochloric acid solution is injected into the reaction container, and phosphorus trichloride is added dropwise at 65° C. and 0.05 MPa to carry out bubbling hydrolysis reaction for 90 minutes.

[0135] In step (3), the preparation method of phosphorous acid is as follows: the phosphorous acid solution is concentrated at 75°C and -0.05MPa for 80 minutes, transferred to a crystallization kettle, cooled to 35°C at 20°C / hour, cooled to room temperature (25°C) at 2°C / hour, and centrifuged to obtain phosphorous acid. The process conditions of centrifugal dehydration are: centrifugation at 15000r / min for 10 minutes.

[0136] In step (4), the dimensions of the reaction tower are: diameter 0.46 m, height 4.6 m; the filling amount of the catalyst is 3 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 2 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts.

[0137] The reaction temperature in the reaction tower is 35°C.

[0138] The product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -3°C at a rate of 1°C / min while stirring. At this temperature, the liquid is filtered and dried to obtain ethyl chloride. The gas phase pressure in the condenser is 0.8MPa, and the outlet temperature of the cooling circulating water is below 38°C.

[0139] The stirring rate is 200r / min.

[0140] The specific method of drying is: the liquid flows through a cylindrical adsorption device filled with calcium chloride, the diameter of the adsorption device is 0.6m, the height is 1.5m, and the liquid flow rate is 300kg / h.

[0141] The various indicators of phosphorous acid obtained in step (3) of Examples 1 to 4 were investigated with reference to HG-T 2520-2006 "Industrial Phosphorous Acid". The results are shown in Table 1.

[0142] Table 1. Phosphorous acid index detection

[0143] Phosphorous acid mass fraction (%) Chloride mass fraction (%) Example 1 ≥99.8 ≤0.001 Example 2 ≥99.8 ≤0.001 Example 3 ≥99.8 ≤0.001 Example 4 ≥99.8 ≤0.001

[0144] The yield of ethyl chloride was calculated according to the following formula for the production methods of Examples 1 to 4 and Comparative Examples 1 and 2: Yield of ethyl chloride (%) = molar amount of product ethyl chloride / molar amount of raw material ethanol × 100%. The results are shown in Table 2.

[0145] Table 2. Comparison of ethyl chloride yields

[0146] Ethyl chloride yield (%) Example 1 95.6 Example 2 95.7 Example 3 95.9 Example 4 96.5 Comparative Example 1 90.1 Comparative Example 2 90.3

[0147] The various indicators of ethyl chloride obtained in step (3) were investigated with reference to HG-T 5713-2020 "Ethyl Chloride for Industrial Use". The results are shown in Table 3.

[0148] Table 3. Ethyl chloride index detection

[0149]

[0150]

[0151] As can be seen from Tables 1, 2 and 3, the production methods of Examples 1 to 4 have high phosphorous acid purity, high ethyl chloride yield and high purity.

[0152] In comparative example 1, commercially available powdered activated carbon was directly used to replace the carrier when preparing the catalyst. In comparative example 2, 1-ethyl-3-methylimidazole dicyanamide salt was omitted when preparing the catalyst. The yield and purity of the product ethyl chloride were significantly reduced, indicating that the catalyst specifically prepared by the present invention helps to promote the reaction of hydrogen chloride and ethanol and improve the yield of ethyl chloride.

[0153] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A clean production method for co-producing phosphorous acid with ethyl chloride, characterized in that: The specific steps are as follows: (1) first preparing a carrier with activated carbon as a core and amorphous alumina as a shell, then uniformly dispersing zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide in anhydrous ethanol to obtain a zinc chloride solution, and then compounding the carrier with the zinc chloride solution to obtain a catalyst for standby use; (2) then mixing phosphorus trichloride with hydrochloric acid solution to carry out hydrolysis reaction to generate phosphorous acid solution and gaseous hydrogen chloride, which are respectively entered into step (3) and step (4); (3) the phosphorous acid solution is vacuum concentrated, crystallized and centrifuged to obtain phosphorous acid; (4) Filling a reaction tower with a catalyst, mixing gaseous hydrogen chloride with vaporized ethanol and passing it into the reaction tower for reaction to obtain ethyl chloride; In parts by weight, the carrier is prepared by the following method: first, ultrasonically dispersing 1 part of powdered activated carbon in 4-5 parts of 1-2% glucose aqueous solution to obtain activated carbon slurry; then, adding 1 part of aluminum chloride to 8-10 parts of distilled water, stirring at 50-60° C. for 15-25 minutes, adding activated carbon slurry while stirring, adding 8-10% ammonia water dropwise under heat preservation and stirring conditions until the system pH is 8, heat preservation and standing for 1-2 hours, filtering to obtain a filter cake, washing with water until there is no chloride ion, drying at 110-120° C. for 10-12 hours, roasting at 550-600° C. for 6-8 hours under nitrogen protection, and crushing to 100-200 meshes to obtain the carrier; The mass ratio of zinc chloride to anhydrous ethanol is 1:7-9, and the molar amounts of zinc chloride and 1-ethyl-3-methylimidazolium dicyanamide are equimolar; ultrasonic dispersion is adopted, and the specific process conditions are: 500-600W ultrasonic oscillation treatment for 20-30 minutes; The specific method of compounding is as follows: adding the carrier to a zinc chloride solution of 11 to 14 times its weight, stirring at room temperature for 4 to 5 hours, heating in a water bath at 70 to 80°C for 6 to 7 hours under closed conditions, keeping it open at 70 to 80°C for 6 to 7 hours, and vacuum drying at 70 to 80°C for 6 to 7 hours. In step (2), a hydrochloric acid solution is injected into a reaction container, and phosphorus trichloride is added dropwise at 65 to 70° C. and 0.05 to 0.08 MPa to perform a bubbling hydrolysis reaction for 90 to 110 minutes; wherein the mass concentration of the hydrochloric acid solution is 30 to 36%, and the volume ratio of phosphorus trichloride to the hydrochloric acid solution is 1:3; In step (3), the preparation method of phosphorous acid is as follows: concentrating the phosphorous acid solution at 75 to 85° C. and -0.05 to -0.07 MPa for 80 to 100 minutes, transferring it to a crystallization kettle, cooling it to 35 to 40° C. at 20 to 30° C. / hour, cooling it to room temperature at 2 to 3° C. / hour, and centrifuging and dehydrating it to obtain phosphorous acid; In step (4), the dimensions of the reaction tower are: diameter 0.46 m, height 4.6 m; the filling amount of the catalyst is 3 / 5 to 4 / 5 of the volume of the reaction tower; gaseous hydrogen chloride and vaporized ethanol are introduced from the bottom of the reaction tower, the introduction rate of gaseous hydrogen chloride is 2 to 3 L / min, and the vaporized ethanol and gaseous hydrogen chloride are introduced in equimolar amounts; The reaction temperature in the reaction tower is 35-40°C; The product discharged from the top of the reaction tower is condensed by a condenser, and the temperature is lowered to -3 to -5°C at a rate of 1 to 2°C / min while stirring. At this temperature, the liquid is filtered and dried to obtain ethyl chloride.

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