Separation continuous operation process and application of sucralose chlorination neutralization solution solvent

Abstract

The invention provides a separation continuous operation process and application of a sucralose chlorination neutralization solution solvent, and relates to the technical field of sucralose production.The separation process specifically comprises the following steps that 1, a chlorination neutralization solution enters a neutralization solution transfer kettle and then enters a pre-concentration kettle, and a trichloroethane gas phase and a material A are obtained; (2) feeding the material A into a concentrated drying kettle through a concentrated solution transfer kettle to obtain a DMF gas phase; (3) feeding the trichloroethane gas phase obtained in the step (1) and the DMF gas phase obtained in the step (2) into a first condenser to obtain a trichloroethane heavy phase and a DMF light phase; (4) feeding the trichloroethane heavy phase and the DMF light phase into a pre-concentration tower, and concentrating to obtain a trichloroethane gas phase and a DMF liquid phase; (5) condensing and dehydrating the trichloroethane gas phase to obtain a finished product trichloroethane; and concentrating the DMF liquid phase to obtain a finished product DMF. The process provided by the invention can effectively separate trichloroethane from DMF.

Description

Technical Field

[0001] The invention relates to the technical field of sucralose production, and in particular to a separation continuous operation process and application of a sucralose chlorination neutralization liquid solvent. Background Art

[0002] Sucralose is the only functional sweetener made from sucrose, with a sweetness that is 600 times that of sucrose. This sweetener has the characteristics of no energy, high sweetness, pure sweetness and high safety, and is currently one of the best functional sweeteners. At present, the industrial production of sucralose mostly adopts the monoester method, that is, DMF (dimethylformamide) is used as a solvent, acetic anhydride is used as an acylating agent to obtain sucrose-6-ethyl ester, and thionyl chloride is usually used as a chlorinating agent and trichloroethane is used as a solvent for chlorination reaction to produce sucralose-6-ethyl ester. The crude sugar is extracted and crystallized, and finally alkaline hydrolysis is carried out in a sodium methoxide solution in a batch reactor to obtain the sucralose product. Due to the numerous processes mentioned above, the operation process of each step is relatively complicated, so the cost is also high.

[0003] Prior art, such as patent CN116323552A, discloses a method for treating a chlorinated neutralized solution of sucralose-6-ester, which specifically comprises the following steps: (1) pre-concentrating, condensing and layering the chlorinated neutralized solution of sucralose-6-ester in sequence to obtain a first DMF light phase and a first trichloroethane heavy phase, respectively; (2) distilling the first trichloroethane heavy phase to obtain a distilled gas phase and a distilled residual liquid, respectively; condensing the distilled gas phase and layering to obtain a second DMF light phase and a second trichloroethane heavy phase, respectively; (3) washing the second trichloroethane heavy phase with water to obtain a first DMF-containing aqueous phase and a third trichloroethane heavy phase, respectively. (4) layering the distilled residual liquid, washing the obtained lower phase with water, and respectively obtaining a second DMF-containing aqueous phase and a fourth trichloroethane heavy phase; (5) rectifying the first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase and the second DMF-containing aqueous phase to obtain a DMF finished product; (6) rectifying the third trichloroethane heavy phase and the fourth trichloroethane heavy phase to respectively obtain a trichloroethane finished product and a residual liquid used for distillation; the method of the invention can improve the conversion rate and daily production capacity of sucralose-6-ester in the chlorinated neutralization liquid, reduce the generation of wastewater and waste activated carbon, reduce the three wastes, reduce energy consumption, and reduce production costs.

[0004] For example, patent CN115672222A discloses a device and method for pretreatment of chlorinated neutralization liquid and solvent recovery in the production of sucralose. The method in the invention specifically includes the following steps: (1) the heavy phase entering the distillation tower is first washed with water to remove DMF, and the heavy phase after washing is sent to the distillation tower for distillation, and the finished product trichloroethane is obtained after condensation; (2) after the distillation is completed, the residual liquid at the bottom of the tower is sent to the residual liquid transfer tank, and then the residual liquid is distilled again to recover trichloroethane, the distillation temperature is controlled to be 65-70°C, the pressure is -0.090~-0.094MPa, and the condensed liquid enters the buffer tank. The invention can obtain trichloroethane with a purity of more than 99.5%, the content of the separated tetramethylurea is more than 90%, and the residual liquid volume is reduced by 90%.

[0005] In view of the problems existing in the prior art, it is necessary to find a separation and continuous operation process and application of the solvent of sucralose chlorination neutralization solution. Summary of the invention

[0006] The present invention aims at the problems existing in the prior art and provides a continuous operation process and application of separation of a solvent of sucralose chlorination neutralization liquid. The process can effectively separate trichloroethane and DMF.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a continuous operation process for separating a solvent of a sucralose chlorination neutralization solution, comprising the following steps:

[0009] (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle to obtain trichloroethane gas phase and material A;

[0010] (2) Material A enters the concentrated drying kettle through the concentrated liquid transfer kettle to obtain DMF gas phase;

[0011] (3) the trichloroethane gas phase obtained in step (1) and the DMF gas phase obtained in step (2) enter a first condenser to obtain a trichloroethane heavy phase and a DMF light phase;

[0012] (4) the trichloroethane heavy phase and the DMF light phase enter a pre-concentrator to be concentrated to obtain a trichloroethane gas phase and a DMF liquid phase;

[0013] (5) The trichloroethane gas phase is condensed and dehydrated to obtain the finished trichloroethane; the DMF liquid phase is concentrated to obtain the finished DMF.

[0014] It is worth mentioning that DMF described in the present invention is specifically dimethylformamide.

[0015] Furthermore, the pressure of the pre-concentration kettle in step (1) is -90 to -100 kPa, and the temperature is 50 to 60°C.

[0016] Preferably, the pressure of the pre-concentration reactor in step (1) is -95 kPa and the temperature is 55°C.

[0017] Furthermore, the chlorination neutralization liquid in step (1) comprises trichloroethane and DMF liquid.

[0018] Furthermore, the trichloroethane gas phase in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase in step (2) is pumped out through a second vacuum pump and enters a first condenser.

[0019] Furthermore, the temperature of the first condenser is below 35°C.

[0020] Furthermore, in step (2), the temperature of the concentrated drying kettle is 55-65°C, and the pressure is -90 to -100 kPa.

[0021] Preferably, the temperature of the concentrated drying kettle in step (2) is 60° C. and the pressure is -95 kPa.

[0022] Furthermore, in step (4), the temperature at the top of the pre-concentration tower is 40-50° C., and the pressure is -90 to -100 kPa.

[0023] Preferably, the temperature of the pre-concentration tower in step (4) is 45° C. and the pressure is -95 kPa.

[0024] Furthermore, the bottom of the pre-concentration tower in step (4) also includes DMF liquid, which is extracted into a concentration and drying kettle. It is worth noting that after the DMF liquid is treated in the concentration and drying kettle, a DMF gas phase is obtained, which is condensed in the second condenser through a second vacuum pump again and returned to the pre-concentration tower. Repeating the above steps can ensure that DMF is recovered by heavy division.

[0025] Furthermore, the bottom temperature of the pre-concentration tower in step (4) is 107-113°C and the pressure is -90 to -100 kPa; the condensation in step (5) is carried out in the second condenser, the temperature of the second condenser is below 35°C, and the dehydration is carried out in the dehydration tower, the temperature of the dehydration tower is 107-113°C and the pressure is -90 to -100 kPa.

[0026] Preferably, the bottom temperature of the pre-concentration tower in step (4) is 111°C and the pressure is -95 kPa; the condensation in step (5) is carried out in the second condenser, the temperature of the second condenser is 30°C, and the dehydration is carried out in the dehydration tower, the temperature of the dehydration tower is 111°C and the pressure is -100 kPa.

[0027] Furthermore, the above-mentioned separation continuous operation process provided by the present invention can be applied in the production of sucralose.

[0028] The technical effect achieved by the present invention is: Compared with the prior art, the technical effect of the present invention is:

[0029] 1) Yield: Increase the yield of solvent recovery. 180 tons of trichloroethane and 290 tons of DMF can be recovered each year.

[0030] 2) Purity: The purity of the recovered DMF and trichloroethane is high enough to be directly recycled.

[0031] 3) Cost: The recovered solvent is recycled to improve production efficiency and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The figure is a schematic diagram of the continuous operation process for separating the solvent of the chlorinated neutralized solution of sucralose according to the present invention. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention.

[0035] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs.

[0036] It is worth noting that the raw materials used in the present invention are all common commercially available products, so their sources are not specifically limited.

[0037] The chlorination neutralization liquid in the present invention comprises trichloroethane and DMF liquid.

[0038] The schematic diagram of the continuous operation process for separating the solvent of the chlorinated neutralized solution of sucralose of the present invention is shown in Figure 1 .

[0039] Example 1

[0040] A continuous operation process for separating a solvent of a sucralose chlorination neutralization solution comprises the following steps:

[0041] (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle (pressure is -90 kPa, temperature is 50°C) to obtain trichloroethane gas phase and material A;

[0042] (2) Material A enters the concentrated drying kettle (temperature 55°C, pressure -90kpa) through the concentrated liquid transfer kettle to obtain DMF gas phase;

[0043] (3) The trichloroethane gas phase obtained in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase obtained in step (2) is pumped out through a second vacuum pump and enters a first condenser, the temperature of the first condenser is 35° C., and a trichloroethane heavy phase and a DMF light phase are obtained;

[0044] (4) The trichloroethane heavy phase and the DMF light phase enter a pre-concentration tower (tower top temperature is 40° C., pressure is -90 kPa, tower bottom temperature is 107° C., pressure is -90 kPa), and are concentrated to obtain a trichloroethane gas phase and a DMF liquid phase; the tower bottom of the pre-concentration tower also contains DMF liquid, and the DMF liquid is treated in a concentration and drying kettle to obtain a DMF gas phase, which is again condensed in a second condenser through a second vacuum pump and returned to the pre-concentration tower. Repeating the above steps can ensure that DMF can be recovered by heavy fractionation;

[0045] (5) The trichloroethane gas phase enters the second condenser for condensation (temperature is 35°C), and then enters the dehydration tower (temperature is 107°C, pressure is -90kPa) for dehydration to obtain the finished trichloroethane; the DMF liquid phase is concentrated to obtain the finished DMF.

[0046] Example 2

[0047] A continuous operation process for separating a solvent of a sucralose chlorination neutralization solution comprises the following steps:

[0048] (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle (pressure is -100 kPa, temperature is 60°C) to obtain trichloroethane gas phase and material A;

[0049] (2) Material A enters the concentrated dry kettle (temperature 65°C, pressure -100 kPa) through the concentrated liquid transfer kettle to obtain DMF gas phase;

[0050] (3) The trichloroethane gas phase obtained in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase obtained in step (2) is pumped out through a second vacuum pump and enters a first condenser, the temperature of the first condenser is 20° C., and a trichloroethane heavy phase and a DMF light phase are obtained;

[0051] (4) The trichloroethane heavy phase and the DMF light phase enter a pre-concentration tower (tower top temperature is 50° C., pressure is −100 kPa, tower bottom temperature is 113° C., pressure is −100 kPa), and are concentrated to obtain a trichloroethane gas phase and a DMF liquid phase; the tower bottom of the pre-concentration tower also contains a DMF liquid, and the DMF liquid is treated in a concentration and drying kettle to obtain a DMF gas phase, which is again condensed in a second condenser through a second vacuum pump and returned to the pre-concentration tower. Repeating the above steps can ensure that DMF can be recovered by heavy fractionation;

[0052] (5) The trichloroethane gas phase enters the second condenser for condensation (temperature is 20°C), and then enters the dehydration tower (temperature is 113°C, pressure is -100kPa) for dehydration to obtain the finished trichloroethane; the DMF liquid phase is concentrated to obtain the finished DMF.

[0053] Example 3

[0054] A continuous operation process for separating a solvent of a sucralose chlorination neutralization solution comprises the following steps:

[0055] (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle (pressure is -100 kPa, temperature is 60°C) to obtain trichloroethane gas phase and material A;

[0056] (2) Material A enters the concentrated dry kettle (temperature 65°C, pressure -100 kPa) through the concentrated liquid transfer kettle to obtain DMF gas phase;

[0057] (3) The trichloroethane gas phase obtained in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase obtained in step (2) is pumped out through a second vacuum pump and enters a first condenser, the temperature of the first condenser is 20° C., and a trichloroethane heavy phase and a DMF light phase are obtained;

[0058] (4) The trichloroethane heavy phase and the DMF light phase enter a pre-concentration tower (tower top temperature is 50° C., pressure is −100 kPa, tower bottom temperature is 113° C., pressure is −100 kPa), and are concentrated to obtain a trichloroethane gas phase and a DMF liquid phase; the tower bottom of the pre-concentration tower also contains a DMF liquid, and the DMF liquid is treated in a concentration and drying kettle to obtain a DMF gas phase, which is again condensed in a second condenser through a second vacuum pump and returned to the pre-concentration tower. Repeating the above steps can ensure that DMF can be recovered by heavy fractionation;

[0059] (5) The trichloroethane gas phase enters the second condenser for condensation (temperature is 20°C), and then enters the dehydration tower (temperature is 113°C, pressure is -100kPa) for dehydration to obtain the finished trichloroethane; the DMF liquid phase is concentrated to obtain the finished DMF.

[0060] Comparative Example 1

[0061] The conventional process in the art is specifically: a continuous operation process for separating the solvent of sucralose chlorination neutralization solution, comprising the following steps:

[0062] (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle (pressure is -95 kPa, temperature is 50°C) to obtain trichloroethane gas phase and material A;

[0063] (2) Material A enters the concentrated dry kettle (temperature 55°C, pressure -95kpa) through the concentrated liquid transfer kettle to obtain DMF gas phase;

[0064] (3) The trichloroethane gas phase obtained in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase obtained in step (2) is pumped out through a second vacuum pump and enters a first condenser, the temperature of the first condenser is 35° C., and a trichloroethane heavy phase and a DMF light phase are obtained;

[0065] (4) The trichloroethane heavy phase and the DMF light phase enter a pre-concentration tower (tower top temperature is 40° C., pressure is -95 kPa, tower bottom temperature is 107° C., pressure is -95 kPa), and are concentrated to obtain a trichloroethane gas phase and a DMF liquid phase; the tower bottom of the pre-concentration tower also contains DMF liquid, and the DMF liquid is treated in a concentration and drying kettle to obtain a DMF gas phase, which is again condensed in a second condenser through a second vacuum pump and returned to the pre-concentration tower. Repeating the above steps can ensure that DMF can be recovered by heavy fractionation;

[0066] (5) The trichloroethane gas phase enters the second condenser for condensation (temperature is 35°C), and then enters the dehydration tower (temperature is 107°C, pressure is -95kpa) for dehydration to obtain the finished trichloroethane; the DMF liquid phase is concentrated to obtain the finished DMF.

[0067] Comparative Example 2

[0068] A continuous operation process for separating a solvent of a sucralose chlorination neutralization solution comprises the following steps:

[0069] (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle (pressure is -100 kPa, temperature is 60°C) to obtain trichloroethane gas phase and material A;

[0070] (2) Material A enters the concentrated dry kettle (temperature 65°C, pressure -100 kPa) through the concentrated liquid transfer kettle to obtain DMF gas phase;

[0071] (3) The trichloroethane gas phase obtained in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase obtained in step (2) is pumped out through a second vacuum pump and enters a first condenser, the temperature of the first condenser is 40° C., and a trichloroethane heavy phase and a DMF light phase are obtained;

[0072] (4) The trichloroethane heavy phase and the DMF light phase enter a pre-concentration tower (tower top temperature is 50° C., pressure is −100 kPa, tower bottom temperature is 113° C., pressure is −100 kPa), and are concentrated to obtain a trichloroethane gas phase and a DMF liquid phase; the tower bottom of the pre-concentration tower also contains a DMF liquid, and the DMF liquid is treated in a concentration and drying kettle to obtain a DMF gas phase, which is again condensed in a second condenser through a second vacuum pump and returned to the pre-concentration tower. Repeating the above steps can ensure that DMF can be recovered by heavy fractionation;

[0073] (5) The trichloroethane gas phase enters the second condenser for condensation (temperature is 40°C), and then enters the dehydration tower (temperature is 113°C, pressure is -100kPa) for dehydration to obtain the finished trichloroethane; the DMF liquid phase is concentrated to obtain the finished DMF.

[0074] The only difference from Example 3 is that the condenser temperature is doubled, the reaction time is shortened but the content is reduced.

[0075] Comparative Example 3

[0076] (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle (pressure is -100 kPa, temperature is 60°C) to obtain trichloroethane gas phase and material A;

[0077] (2) Material A enters the concentrated dry kettle (temperature 65°C, pressure -100 kPa) through the concentrated liquid transfer kettle to obtain DMF gas phase;

[0078] (3) The trichloroethane gas phase obtained in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase obtained in step (2) is pumped out through a second vacuum pump and enters a first condenser, the temperature of the first condenser is 20° C., and a trichloroethane heavy phase and a DMF light phase are obtained;

[0079] (4) The trichloroethane heavy phase and the DMF light phase enter a pre-concentration tower (tower top temperature is 45°C, pressure is -100 kPa, tower bottom temperature is 113°C, pressure is -100 kPa), and are concentrated to obtain a trichloroethane gas phase and a DMF liquid phase; the tower bottom of the pre-concentration tower also contains DMF liquid, and the DMF liquid is treated in a concentration and drying kettle to obtain a DMF gas phase, which is again condensed in a second condenser through a second vacuum pump and returned to the pre-concentration tower. Repeating the above steps can ensure that DMF can be recovered by heavy fractionation;

[0080] (5) The trichloroethane gas phase enters the second condenser for condensation (temperature is 20°C), and then enters the dehydration tower (temperature is 113°C, pressure is -100kPa) for dehydration to obtain the finished trichloroethane; the DMF liquid phase is concentrated to obtain the finished DMF.

[0081] The only difference from Example 3 is that the temperature of the pre-concentration tower is reduced by 5 degrees and the processing amount is reduced.

[0082] Effect detection:

[0083] Detection method: Liquid chromatography detection, the test results are shown in Table 1 below.

[0084] Table 1

[0085]

[0086]

[0087] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A continuous operation process for separating a solvent from a chlorinated neutralized sucralose solution, characterized in that: The following steps are involved: (1) The chlorinated neutralized liquid enters the neutralized liquid transfer kettle, and then enters the pre-concentration kettle to obtain trichloroethane gas phase and material A; (2) Material A enters the concentrated drying kettle through the concentrated liquid transfer kettle to obtain DMF gas phase; (3) the trichloroethane gas phase obtained in step (1) and the DMF gas phase obtained in step (2) enter a first condenser to obtain a trichloroethane heavy phase and a DMF light phase; (4) the trichloroethane heavy phase and the DMF light phase enter a pre-concentrator to be concentrated to obtain a trichloroethane gas phase and a DMF liquid phase; (5) The trichloroethane gas phase is condensed and dehydrated to obtain the finished trichloroethane; The DMF liquid phase is concentrated to obtain finished DMF.

2. The separation continuous operation process according to claim 1, characterized in that: The pressure of the pre-concentration kettle in step (1) is -90 to -100 kPa, and the temperature is 50 to 60°C.

3. The separation continuous operation process according to claim 1, characterized in that: The number of the pre-concentration kettles in step (1) is ≥1.

4. The separation continuous operation process according to claim 1, characterized in that: The chlorination neutralization liquid in step (1) comprises trichloroethane and DMF liquid.

5. The separation continuous operation process according to claim 1, characterized in that: The trichloroethane gas phase in step (1) is pumped out through a first vacuum pump and enters a first condenser, and the DMF gas phase in step (2) is pumped out through a second vacuum pump and enters a first condenser.

6. The separation continuous operation process according to claim 1, characterized in that: The temperature of the concentrated drying kettle in step (2) is 55-65°C and the pressure is -90 to -100 kPa.

7. The separation continuous operation process according to claim 1, characterized in that: The temperature at the top of the pre-concentration tower in step (4) is 40-50°C, and the pressure is -90 to -100 kPa.

8. The separation continuous operation process according to claim 1, characterized in that: The bottom of the pre-concentration tower in step (4) also includes DMF liquid, and the DMF liquid is extracted into a concentration and drying kettle.

9. The separation continuous operation process according to claim 1, characterized in that: The bottom temperature of the pre-concentration tower in step (4) is 107-113°C and the pressure is -90 to -100 kPa; the condensation in step (5) is carried out in the second condenser, the temperature of the second condenser is below 35°C, and the dehydration is carried out in the dehydration tower, the temperature of the dehydration tower is 107-113°C and the pressure is -90 to -100 kPa.

10. Use of the separation continuous operation process according to any one of claims 1 to 9 in the production of sucralose.

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