Waste liquid treatment method in p-toluenesulfonyl methyl isocyanide production process

Abstract

The invention discloses a waste liquid treatment method in a p-toluenesulfonyl methyl isocyanide production process, which comprises the following steps: S1, separating water and sodium chloride in a first-step mother solution through an MVR (mechanical vapor recompression) evaporator, subsequently supplying the water to an intermediate workshop for use, and exporting the sodium chloride; s2, carrying out reduced pressure distillation on the second-step mother liquor in a distillation kettle to obtain tetrahydrofuran, and returning the tetrahydrofuran to an intermediate workshop for self-use; adding an alkali solution into the tetrahydrofuran-removed two-step mother liquor to decompose triethylamine salt, standing for liquid separation, and returning triethylamine to an intermediate workshop from a receiving tank for self-use; the collected salt solution is treated by an MVR evaporator, and distilled water enters a water storage tank and is subsequently used in an intermediate workshop; separated sodium phosphate and sodium chloride are exported. According to the method, triethylamine can be recycled, sodium phosphate and water can be separated out, water can be returned to an intermediate production workshop to be put into use again, salt can be sold after being packaged, and remarkable environmental protection and economic benefits are achieved.

Description

TECHNICAL FIELD

[0001] The application relates to a waste liquid treatment method in the production of p-toluenesulfonylmethyl isocyanide, and belongs to the technical field of waste liquid treatment. BACKGROUND

[0002] The production process of p-toluenesulfonylmethyl isocyanide generally comprises two steps, i.e., preparation of an intermediate and preparation of a final product, and mother liquor is generated in each production step. Triethylamine is used as an acid-binding agent in the production of the final product, and due to a large amount of triethylamine used in the production, the triethylamine exists in the form of a hydrochloride salt of triethylamine in the mother liquor after the reaction is completed.

[0003] A method for recovering triethylamine from wastewater containing a hydrochloride salt of triethylamine in the prior art generally comprises the following steps: (1) the wastewater is heated to 60 DEG C, and then 20% pure liquid alkali is added to adjust the pH value of the wastewater to 8-10, (2) the triethylamine is separated from the hydrochloride salt of triethylamine after being kept warm for half an hour, (3) after the keeping warm is completed, the water layer is separated after being kept still, and the water layer is removed. After the water layer is removed, anhydrous sodium sulfate is added to the remaining organic layer to dry for 1 hour, and then filtration is performed. The filtrate after the filtration is distilled at normal pressure, and the distillate is collected.

[0004] The traditional triethylamine recovery method is relatively complicated, the recovery time is relatively long, the energy consumption is relatively high, and the environmental protection and economic benefits are relatively poor.

[0005] In view of the above problems, the application is proposed. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the application is to provide a waste liquid treatment method in the production of p-toluenesulfonylmethyl isocyanide, which comprises the following steps:

[0007] S1: one-step mother liquor treatment

[0008] Water and sodium chloride in the one-step mother liquor are separated through an MVR evaporator, the water enters a water storage tank and is used in subsequent one-step reaction in an intermediate workshop, and the sodium chloride is directly granulated and packaged for sale;

[0009] S2: two-step mother liquor

[0010] S21: separation of tetrahydrofuran

[0011] The two-step mother liquor is subjected to vacuum distillation in a distillation kettle to obtain tetrahydrofuran, and then the water in the tetrahydrofuran is removed, and then the tetrahydrofuran is returned to the intermediate workshop for self-use in two-step reaction;

[0012] S22: separation of triethylamine

[0013] The base solution is added to the two-step mother liquor from which tetrahydrofuran is removed in step S21, so that the triethylamine salt is decomposed to obtain free triethylamine and sodium chloride and sodium phosphate, and the triethylamine and the salt solution are collected by standing and separating, and then the water in the triethylamine is removed, and the triethylamine is returned to the intermediate workshop for use in the two-step reaction stage.

[0014] S23: Separation of salt

[0015] The salt solution collected in step S22 is treated by an MVR evaporator, the evaporated water is stored in a water tank for subsequent use in the intermediate workshop, and the separated sodium phosphate and sodium chloride are directly granulated and packaged for sale.

[0016] Preferably, the main components of the one-step mother liquor in step S1 are 58.08% water, 8.66% NaCl, 6.86% formaldehyde, 23.23% formamide and 3.17% HCl.

[0017] Preferably, the main components of the two-step mother liquor in step S2 are 12.6% phosphate, 12% triethylamine salt, 15% tetrahydrofuran and 60.4% water.

[0018] Preferably, step S1 is specifically: the one-step mother liquor is directly pumped into an MVR evaporator by a corrosion-resistant magnetic pump, the feeding amount is 2 t / h, the water and sodium chloride in the one-step mother liquor are separated by the MVR evaporator, the water is stored in a water tank for subsequent use in the one-step reaction in the intermediate workshop, and the sodium chloride is directly granulated and packaged for sale.

[0019] Preferably, step S21 is specifically: the two-step mother liquor is pumped into a distillation kettle by a corrosion-resistant magnetic pump, stirring is started, a vacuum pump is started, the temperature is controlled at 35-45°C for reduced pressure distillation, the evaporated tetrahydrofuran is condensed by a stainless steel condenser and flows to a tetrahydrofuran receiving tank; At this time, the evaporated tetrahydrofuran has a large amount of water, which needs to be removed by a bipolar membrane, and the tetrahydrofuran after removing the water is returned to the intermediate workshop for use in the two-step reaction.

[0020] Preferably, the condensing medium in step S21 is cold brine.

[0021] Preferably, step S22 is specifically: the remaining two-step mother liquor in step S21 is pumped into the enamel alkali adjusting tank by a corrosion-proof magnetic pump, a liquid alkali solution is pumped in, and the pH of the solution is adjusted to be greater than 11, at this time, the triethylamine salt is decomposed to obtain free triethylamine and sodium chloride and sodium phosphate; after stirring for 1 h, the stirring is stopped, and the system is left to stand for 1 h, the triethylamine and the salt solution are separated, the triethylamine is in the upper layer, and the salt solution is in the lower layer, and the triethylamine and the salt solution are collected respectively; the triethylamine contains part of water, the triethylamine is pumped into a triethylamine distillation tower through a corrosion-proof magnetic pump, normal pressure distillation is set, the temperature is 90-95 DEG C, the distilled triethylamine is condensed through a stainless steel condenser, enters a fractional distillation tank, the distilled triethylamine is recycled to the distillation kettle through the distillation tower by a corrosion-proof magnetic pump, and after intermediate detection of water content, the triethylamine in the fractional distillation tank enters a receiving tank and a distillation kettle respectively. When the water content is detected to be unqualified, the valve of the triethylamine receiving tank is closed, the triethylamine in the fractional distillation tank does not enter the receiving tank, and all enters the distillation kettle for next treatment, and the triethylamine returns to the intermediate workshop from the receiving tank for self-use in the two-step reaction stage.

[0022] Preferably, step S23 is specifically: the salt solution collected in step S22 is pumped into an MVR evaporator through a corrosion-proof magnetic pump, the feeding amount is 2 t / h, the distilled water enters a water storage tank for subsequent use in the intermediate workshop; and the sodium phosphate and the sodium chloride are directly granulated, packaged and sold.

[0023] The beneficial effects of the present application are as follows:

[0024] The present application not only recycles triethylamine, but also is used with an MVR evaporation device to separate sodium phosphate, sodium phosphate and water, the water can be returned to the intermediate production workshop for reuse, and the salt can be packaged and sold, so that remarkable environmental protection and economic benefits are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a one-step mother liquor treatment flow chart.

[0026] Figure 2 It is a two-step mother liquor treatment flow chart. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application is further described below in combination with specific embodiments.

[0028] REFERENCE Figure 1 and Figure 2The mother liquor treated in the present application is divided into one-step mother liquor and two-step mother liquor. The main components of the one-step mother liquor are water (58.08%), NaCl (8.66%), formaldehyde (6.86%), formamide (23.23%), and HCl (3.17%). The main components of the two-step mother liquor are phosphate (12.6%), triethylamine salt (12%), tetrahydrofuran (15%), and water (60.4%). The main purpose of the present application is to recover water and NaCl in the one-step mother liquor, and to recover tetrahydrofuran, triethylamine, phosphate, NaCl, and water in the two-step mother liquor. Tetrahydrofuran, triethylamine, and water are used in the intermediate workshop; NaCl and sodium phosphate are sold.

[0029] The one-step mother liquor can be directly distilled and separated, and the water is returned to the intermediate workshop for self-use; the NaCl separated by distillation is granulated and packaged for sale. The two-step mother liquor needs to be first distilled under reduced pressure to separate tetrahydrofuran, and then treated by a bipolar membrane water removal device for self-use in the two-step reaction; the remaining two-step mother liquor is adjusted with a 30% sodium hydroxide solution, the triethylamine salt is converted into triethylamine, and after standing, the solution is layered, the upper layer of triethylamine is returned to the intermediate workshop for self-use after distillation; the lower layer of salt solution is evaporated to separate water, NaCl, and sodium phosphate, the water is self-used, and the salt is sold.

[0030] S1: one-step mother liquor treatment (separation of salt and water)

[0031] The one-step mother liquor is directly pumped into the MVR evaporator from the one-step mother liquor tank in the tank area by a corrosion-resistant magnetic pump, the water and sodium chloride in the one-step mother liquor are separated by the MVR evaporator (feed quantity 2 t / h), the water enters the water storage tank, and is subsequently used in the intermediate workshop for one-step reaction. The sodium chloride is directly granulated, packaged, and sold. The kettle residue is distilled twice by MVR.

[0032] S1: two-step mother liquor (separation of tetrahydrofuran, triethylamine, water, and salt)

[0033] (1) Separation of tetrahydrofuran

[0034] 5000L of two-step mother liquor is pumped into two 6300L two-step mother liquor distillation kettles by a corrosion-resistant magnetic pump, stirring is started, a vacuum pump is started, and the temperature is controlled at 35-45°C for distillation under reduced pressure, the distilled tetrahydrofuran is cooled by a stainless steel condenser (the condensing medium is cold brine), flows into a 3000L tetrahydrofuran receiving tank, and about 700-800L of tetrahydrofuran is collected; at this time, the distilled tetrahydrofuran has a relatively large water content, which needs to be removed by 200kg / h of a bipolar membrane. The tetrahydrofuran after water removal is returned to the intermediate workshop for self-use in the two-step reaction.

[0035] (2) Separation of triethylamine

[0036] In 2 pairs of 6300L enamel alkali tank with corrosion magnetic pump into about 4200-4300L of the remaining two-step mother liquor, 1276kg of 30% liquid caustic soda solution, adjust the solution pH>11, at this time the salt decomposition of triethylamine and sodium chloride, sodium phosphate. After stirring for 1h, turn off the stirring, the system is stationary 1h, start the liquid, triethylamine and salt solution layering, triethylamine in the upper layer, salt solution in the lower layer.

[0037] The upper layer of triethylamine containing part of the water, triethylamine corrosion magnetic pump into the triethylamine distillation column, set the atmospheric distillation, temperature 90-95℃, the distillation of triethylamine through stainless steel condenser, into the fractionating tank, with corrosion magnetic pump distillation of triethylamine through distillation column return to the distillation kettle cycle, intermediate detection of moisture qualified, fractionating tank triethylamine according to certain proportion, respectively into the receiving tank and distillation kettle. When the detection of moisture is not qualified, close the triethylamine receiving tank valve, triethylamine in the fractionating tank no longer enter the receiving tank, all into the distillation kettle for next processing. Triethylamine from the receiving tank back to the intermediate workshop two-step reaction stage for use.

[0038] (3) the separation of salt

[0039] Salt solution through corrosion magnetic pump into MVR evaporator, the feed rate of 2t / h, the water into the water storage tank, subsequent use of intermediates workshop; sodium phosphate, sodium chloride directly into granules, packaged for sale. There is no separation of waste liquid.

[0040] Reaction equation: (only two-step mother liquor separation triethylamine process will have a reaction)

[0041] 1, triethylamine hydrochloride + sodium hydroxide

[0042] (C2H5)3NH + Cl - +NaOH→(C2H5)3N+NaCl+H2O

[0043] 2, triethylamine phosphate + sodium hydroxide

[0044] (C2H5)3NH + H2PO4 - +NaOH→(C2H5)3N+NaH2PO4sodium dihydrogen phosphate+H2O

[0045] The foregoing merely illustrates the principles of the application and application of its leading features. This application is not limited to the exact details shown above and described herein, and obvious modifications will occur to those skilled in the art. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and without intent that the application be limited to the subjects shown or described, the scope of the application being indicated by the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.

[0046] Furthermore, it should be understood that although the description above is based on embodiments, not every embodiment contains only one independent technical solution, and the description above is only for the sake of clarity, and those skilled in the art should understand the description as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for treating waste liquid in the production of p-tolylsulfonylmethyl isocyanide, characterized by, Comprising the following steps: S1: one-step mother liquor treatment The water and sodium chloride in the one-step mother liquor are separated by an MVR evaporator, the water is fed into a water storage tank for subsequent use in the one-step reaction in the intermediate workshop, and the sodium chloride is directly granulated and packaged for external sale. S2: two-step mother liquor S21: separation of tetrahydrofuran The two-step mother liquor is distilled under reduced pressure in a distillation kettle to obtain tetrahydrofuran, and then the water in the tetrahydrofuran is removed, and then returned to the intermediate workshop for self-use in the two-step reaction. S22: separation of triethylamine An alkali solution is added to the two-step mother liquor from which the tetrahydrofuran has been removed in step S21 to decompose the triethylamine salt to obtain free triethylamine and sodium chloride and sodium phosphate, and the mixture is allowed to stand and separate into an upper layer of triethylamine and a lower layer of a salt solution, and then the triethylamine and the salt solution are collected separately, and then the water in the triethylamine is removed, and the triethylamine is returned to the intermediate workshop from a receiving tank for self-use in the two-step reaction. S23: separation of salt The salt solution collected in step S22 is treated by an MVR evaporator, the water evaporated is fed into a water storage tank for subsequent use in the intermediate workshop, and the separated sodium phosphate and sodium chloride are directly granulated and packaged for external sale.

2. A process for the treatment of waste liquids in the production of p-tolylsulfonylmethyl isocyanide according to claim 1, characterized in that, The main components of the one-step mother liquor in step S1 are 58.08% water, 8.66% NaCl, 6.86% formaldehyde, 23.23% formamide, and 3.17% HCl.

3. A process for the treatment of waste liquids in the production of p-tolylsulfonylmethyl isocyanide as claimed in claim 1, characterized in that, The main components of the two-step mother liquor in step S2 are 12.6% phosphate, 12% triethylamine salt, 15% tetrahydrofuran, and 60.4% water.

4. A process for treating waste liquid in the production of p-tolylsulfonylmethyl isocyanide according to Claim 1, characterized by, Step S1 specifically: the one-step mother liquor is directly fed into the MVR evaporator by a corrosion-resistant magnetic pump, the feed amount is 2 t / h, the water and sodium chloride in the one-step mother liquor are separated by the MVR evaporator, the water is fed into a water storage tank for subsequent use in the one-step reaction in the intermediate workshop, and the sodium chloride is directly granulated and packaged for external sale.

5. A process for treating waste liquid in the production of p-tolylsulfonylmethyl isocyanide according to Claim 1, characterized by, Step S21 specifically: the two-step mother liquor is fed into the distillation kettle by a corrosion-resistant magnetic pump, the stirring is turned on, the vacuum pump is turned on, the temperature is controlled at 35-45°C for distillation under reduced pressure, the evaporated tetrahydrofuran is condensed by a stainless steel condenser and flows into a tetrahydrofuran receiving tank; At this time, the evaporated tetrahydrofuran has a relatively large amount of water, which needs to be removed by a bipolar membrane, and the tetrahydrofuran after removing the water is returned to the intermediate workshop for self-use in the two-step reaction.

6. The waste liquid treatment method in the production of p-toluenesulfonylmethylisocyanate as described in claim 5, characterized in that, The condensing medium in step S21 is cold brine.

7. A process for treating waste liquids from the production of p-tolylsulfonylmethyl isocyanide as defined in claim 1, wherein The step S22 is specifically: the remaining two-step mother liquor in step S21 is pumped into the enamel alkali adjusting tank by a corrosion-proof magnetic pump, a liquid alkali solution is pumped in, and the pH of the solution is adjusted to be greater than 11, at this time, the triethylamine salt is decomposed to obtain free triethylamine and sodium chloride and sodium phosphate; after stirring for 1 h, the stirring is stopped, the system is left to stand for 1 h, the triethylamine and the salt solution are separated, the triethylamine is in the upper layer, and the salt solution is in the lower layer, and the triethylamine and the salt solution are collected respectively; the triethylamine contains part of water, the triethylamine is pumped into a triethylamine distillation tower by a corrosion-proof magnetic pump, normal pressure distillation is set, the temperature is 90-95 DEG C, the distilled triethylamine is condensed by a stainless steel condenser, enters a fractional distillation tank, the distilled triethylamine is pumped into the distillation tower by a corrosion-proof magnetic pump and returned to the distillation kettle for circulation, after the intermediate water content is qualified, the triethylamine in the fractional distillation tank is respectively introduced into a receiving tank and a distillation kettle, and when the water content is unqualified, the valve of the triethylamine receiving tank is closed, the triethylamine in the fractional distillation tank is not introduced into the receiving tank, and is all introduced into the distillation kettle for next treatment, and the triethylamine is returned to the intermediate workshop from the receiving tank for self-use in the two-step reaction stage.

8. A process for treating waste liquids from the production of p-tolylsulfonylmethyl isocyanide as defined in claim 1, wherein, The step S23 is specifically: the salt solution collected in step S22 is pumped into an MVR evaporator by a corrosion-proof magnetic pump, the feeding amount is 2 t / h, the distilled water is introduced into a water storage tank, and is used subsequently in the intermediate workshop; the sodium phosphate and the sodium chloride are directly granulated, packaged and sold.

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