EA043124B1 - OBTAINING HYDROXYETHYLPIPERAZINE - Google Patents

Description

Piperazine (PIP) is an organic compound that includes a 6-membered ring containing two nitrogen atoms. Piperazine can be formed as a by-product during the ammoniation of 1,2-dichloroethane or ethanolamine. Hydroxyethylpiperazine (HEP) is a piperazine that additionally contains a hydroxyethyl group, which may be referred to as 1-(2-hydroxyethyl)piperazine. For example, hydroxyethylpiperazine may have the following structure:

Hydroxyethylpiperazine can be obtained by the reaction of ethoxylation of piperazine (for example, by the reaction of previously obtained piperazine with ethylene oxide). Both hydroxyethylpiperazine and dihydroxyethylpiperazine (DIGEP) can be formed in the process for producing hydroxyethylpiperazine. The product obtained may be used as a mixture or additional processing steps may be carried out to purify the product streams and obtain the desired product. In addition, this method can be modified so that the production of one piperazine is more favorable than that of another piperazine. For example, using a higher ratio of moles of ethylene oxide to moles of piperazine can promote the formation of dihydroxyethylpiperazine and reduce the yield of hydroxyethylpiperazine, this is unfavorable if the goal is to obtain hydroxyethylpiperazine with high purity. In addition, using low ratios of moles of ethylene oxide to moles of piperazine can result in a significant amount of unreacted piperazine, and separation of unreacted piperazine in an industrial scale process can be difficult because the piperazine solidifies at room temperature. Thus, it is necessary to use a method for the production of hydroxyethylpiperazine, which is able to continuously monitor the value of the ratio of moles of ethylene oxide to the number of moles of piperazine, in order to minimize the influence of high and lower values of the ratio of moles of ethylene oxide to the number of moles of piperazine.

International Application Publication No. WO/2017/011283 discloses a process for the preparation of hydroxyalkylpiperazines, which comprises (i) loading a feed stream containing piperazine into the first position of a reactive distillation column, and (ii) loading a feed stream containing C2-C8 alkylene oxide into one or more other reactive distillation column positions. While the use of reactive distillation may promote the formation of monohydroxyethylpiperazine and/or eliminate the need for a separate multi-stage distillation, alternative processes are needed that use standard continuous equipment to further enable large quantities of hydroxyethylpiperazine to be produced economically on an industrial scale.

Brief summary of the invention

Embodiments can be carried out using a continuous process for the production of hydroxyethylpiperazine, which includes loading pure piperazine, recycled piperazine and ethylene oxide into a reactor to obtain crude hydroxyethylpiperazine, where the reactor is a tank reactor with continuous stirring or a reactor with a perfect displacement. The method further includes continuously feeding crude hydroxyethylpiperazine exiting the reactor into a distillation system that includes at least one distillation column, at least a recycle piperazine stream and a hydroxyethylpiperazine stream are obtained in the distillation system, the recycle piperazine stream contains recycle piperazine, which is loaded into the reactor to obtain crude hydroxyethylpiperazine, and the hydroxyethylpiperazine stream contains at least 60 wt.% hydroxyethylpiperazine, based on the total weight of the hydroxyethylpiperazine stream.

Brief description of the drawings

The details of the embodiments will become clearer to those of ordinary skill in the art from the detailed description of exemplary embodiments given with reference to the accompanying drawings, in which the following is presented.

In FIG. 1 is a process flow diagram illustrating a typical continuous reactive distillation process using recycle stream to produce hydroxyethylpiperazine according to Working Examples 1 and 2.

In FIG. 2 is a process flow diagram illustrating a semi-batch reaction and distillation process without using a recycle stream for producing hydroxyethylpiperazine according to Comparative Example A.

Detailed description of the invention

The present invention provides a continuous process for the production of hydroxyethylpiperazine (also referred to as HEP in the present invention) which utilizes a recycle piperazine stream fed to a reactor in conjunction with a distillation procedure in which, after the separation procedure, the piperazine is recycled back to the reactor. The reactor is a continuously stirred tank reactor or a plug flow reactor. In a continuous process, a low ratio of moles of ethylene oxide to moles of piperazine is used when added to the reactor, and unreacted piperazine is recycled back to the reactor. A continuous process using a reactor and a recycle stream can provide unexpectedly high piperazine conversion and high selectivity for hydroxyethylpiperazine in industrial scale production, for example, compared to the selectivity for dihydroxyethylpiperazine (also called DIGEP in the present invention). In addition, the continuous process allows the reactor to continuously monitor the value of the ratio of moles of ethylene oxide to the number of moles of piperazine in the reactor and be able to control it in real time.

A continuously stirred tank reactor (in the present invention and in the industry also referred to as ERRP) means a tank reactor equipped with an agitator that operates in a steady state with continuous input of a stream of reactants into the reactor and withdrawal of products from the reactor and with continuous stirring. A plug-flow reactor (in the present invention and in the industry also referred to as PEV) means a tubular reactor, which is one long tubular reactor or a plurality of short tubular reactors, which operates in a steady state with a stream of reactants continuously introduced into the inlet of the tubular reactor and products exiting from the outlet. openings of the tubular reactor (the outlet is located at the end of the tube opposite the end on which the inlet is located). The plug flow reactor may include flow obstructions.

A high piperazine conversion means that the piperazine conversion is greater than 0.70 (e.g., greater than 0.75, greater than 0.80, greater than 0.85, greater than 0.90, greater than 0.95, greater than 0.96, etc.). P.)

High selectivity means that the number of moles of hydroxyethylpiperazine (in the stream of HEPTO) in terms of the number of moles of pure piperazine loaded into the reactor (in the stream of HIPP, in Fig. 1) is at least 50% and the number of moles of dihydroxyethylpiperazine in terms of the number of moles of pure piperazine is less than 50%. For example, the HEP yield may be 55 to 100% (eg, 60 to 100%, 65 to 100%, 60 to 99%, 60 to 95%, 65 to 85%, etc.). The number of moles of DIGEP in terms of the number of moles of pure piperazine loaded into the reactor (in the PIP-INPUT stream) can be from 0 to 45% (for example, from 0 to 40%, from 0 to 35%, from 1 to 40%, from 5 to 40%, 15 to 35%, etc.).

In FIG. 1 is a flow chart of a typical process that uses a continuous reaction (e.g., a continuous charge of at least pure piperazine and recycled piperazine, and optionally a continuous charge of ethylene oxide) in conjunction with a distillation procedure to separate unreacted piperazine from a product stream to form recycled piperazine. . The method may further include adding a catalyst such as an ethoxylation catalyst (eg, boron-based catalysts).

In particular, as shown in FIG. 1, the ethylene oxide (EO-INPUT) and piperazine (PIP-INPUT) feed streams are continuously fed into a continuous reactor (eg, a continuously stirred tank reactor or a plug flow reactor). The product obtained in the reactor, which is the crude hydroxyethylpiperazine (NHEP), is a mixture that contains unreacted piperazine, hydroxyethylpiperazine, dihydroxyethylpiperazine and water. The product obtained in the reactor is continuously loaded into a distillation system (DIST, which includes, for example, at least one distillation column) for the separation procedure. The distillation system can be charged with one or more streams of water (WATER-INPUT), for example, to dilute one or more streams and/or to control the freezing temperature of one or more streams. At least three streams may be formed in the distillation system. In particular, a hydroxyethylpiperazine product stream (HEP-OUT), a dihydroxyethylpiperazine product stream (DIHEP-OUT) and a recycle piperazine stream (RIP-RC) can be formed. The hydroxyethylpiperazine product stream may be the end product stream and/or may be further processed to form the end product. The dihydroxyethylpiperazine product stream may be the end product stream, may be further processed to form the end product and/or may be discarded.

The piperazine recycle stream is fed back to the reactor, for example as a continuous piperazine recycle stream being fed into the reactor.

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In FIG. 2 is a process flow diagram using a comparative semi-batch reaction and distillation procedure. However, unreacted piperazine exiting the distillation system is not recycled back to the semi-batch reactor. The semi-batch reactor is loaded with an initial batch of piperazine (PIPVOD) and continuously loaded with ethylene oxide (EO-INTRODUCTION), and after the components are allowed to react in the semi-batch reactor, the crude hydroxyethylpiperazine (NHEP) exits the reactor and enters the distillation system (DIST ) for the separation procedure. The distillation system can be loaded with a stream of water (WATER-INPUT). There are three streams in the distillation system. In particular, a hydroxyethylpiperazine product stream (HEP-LEV), a dihydroxyethylpiperazine product stream (DIHEP-OUT) and a piperazine stream (PIP-RC) are formed, which are not recycled back to the reactor. In particular, in this process, the piperazine stream (PIP-RC) is not fed as a continuous stream back to the semi-batch reactor in order to achieve high piperazine conversion and high selectivity for hydroxyethylpiperazine in industrial scale production.

System designed to produce hydroxyethylpiperazine

A continuous process for producing hydroxyethylpiperazine may include (i) continuously feeding a stream of freshly made piperazine into a reactor (e.g., a continuously stirred or agitated plug reactor), (ii) continuously feeding an ethylene oxide stream into the reactor, (iii) continuously feeding a recycle stream of piperazine into the reactor, (iv) continuously carrying out in the reactor the reaction of piperazine with ethylene oxide to obtain a crude hydroxyethylpiperazine product, (v) loading the crude hydroxyethylpiperazine product into a distillation system that includes at least one distillation column, and (vi) receiving in a distillation recycle piperazine flow system. It should be understood that a continuous process means a process in which materials are processed continuously for a defined period of time (e.g., for at least 1 hour), and is distinct from a batch or semi-batch process in which materials are processed in stages. .

The distillation system may include at least one distillation column. If two or more distillation columns are used, the distillation columns may be connected in series and/or in parallel. If a single distillation column is used, then the distillation column may include a plurality of distillation sections which are arranged in such a way that they operate similarly to the theoretical use of two or more distillation columns, with each section producing a theoretical overhead stream and a bottom stream.

For example, if the distillation system includes two or more distillation sections/columns, then the first distillation section/column may receive a crude hydroxyethylpiperazine product stream exiting the reactor. In the first distillation section/column, an overhead stream can be obtained which contains water and piperazine, then this stream is used to obtain recycle piperazine, which is loaded back into the reactor. In addition, a bottom stream can be obtained in the first distillation section/column, which contains hydroxyethylpiperazine and dihydroxyethylpiperazine. Thus, in the first distillation section/column of the distillation system, the recycle piperazine stream can be separated before the dihydroxyethylpiperazine stream and the hydroxyethylpiperazine stream are separated from each other.

The second distillation section/column may be fed with an overhead stream exiting the first distillation section/column to separate water from piperazine. The overhead stream leaving the second distillation section/column may contain water and the bottom stream may contain piperazine, which is used to produce a recycle piperazine stream. The bottoms stream leaving the second distillation section/column can be further processed outside the distillation system to control the piperazine concentration and then fed back into the reactor. The overhead stream leaving the second distillation section/column may be waste water and/or may be further processed to be usable.

The third distillation section/column may be fed with the bottom stream leaving the first distillation section/column to separate the hydroxyethylpiperazine from the dihydroxyethylpiperazine. The overhead stream leaving the third distillation section/column may contain hydroxyethylpiperazine and the bottom stream may contain dihydroxyethylpiperazine. Additional distillation sections/columns may be included in the distillation system, for example for further purification of recycle piperazine and hydroxyethyl piperazine and/or dihydroxyethyl piperazine product streams.

The hydroxyethylpiperazine product stream exiting the distillation system may have an HEP purity of at least 60 wt.% (at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.% and so on.). The dihydroxyethylpiperazine product stream exiting the distillation system may have a DIGEP purity of at least 35 wt.% (at least wt.%, at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, not less than 80 wt.%, etc.), and may optionally be further diluted with one or more solvents.

When added to the reactor, the ratio of moles of ethylene oxide to the number of moles of pure piperazine (freshly prepared piperazine loaded into the reactor) can be more than 1.01 (for example, more than 1.02, more than 1.05, more than 1.10, more than 1.15, more than 1.20, more than 1.22, etc.). The ratio of moles of ethylene oxide to moles of pure piperazine may be less than 4.00 (e.g., less than 3.50, less than 3.00, less than 2.50, less than 2.00, less than 1.99, less than 1.50, etc.). P.). When added to the reactor, the ratio of moles of ethylene oxide to total moles of piperazine, including the number of moles of pure piperazine and the number of moles of recycled piperazine, can be less than 1.01 (less than 1.00, less than 0.90, less than 0.85, less than 0, 80, less than 0.75, less than 0.70) and more than 0.01 (for example, more than 0.05, more than 0.10, more than 0.20, more than 0.30, more than 0.40, more than 0.50, more than 0.60, etc.). For example, the ratio of moles can be from 0.01 to 1.00.

The hydroxyethylpiperazine product stream exiting the distillation system contains at least 60% by weight of hydroxyethylpiperazine, based on the total weight of the hydroxyethylpiperazine stream. For example, it contains from 60 to 100 wt.% (for example, from 65 to 100 wt.%, from 70 to 100 wt.%, from 80 to 100 wt.%, from 85 to 100 wt.%, from 90 up to 100 wt.%, from 95 to 100 wt.%, from 97 to 100 wt.%, from 98 to 100 wt.%, from 99 to 100 wt.%, etc.) of hydroxyethylpiperazine, the remainder being other components contained in the crude hydroxyethylpiperazine.

The dihydroxyethylpiperazine product stream contains at least 35% by weight of dihydroxyethylpiperazine, based on the total weight of the dihydroxyethylpiperazine stream. So, for example, it contains from 35 to 100 wt.% (for example, from 40 to 100 wt.%, from 50 to 100 wt.%, from 60 to 100 wt.%, from 70 to 100 wt.%, from 80 up to 100 wt.%, from 90 to 100 wt.%, from 91 to 100 wt.%, etc.) of dihydroxyethylpiperazine, the remainder being other components contained in the crude dihydroxyethylpiperazine. The dihydroxyethylpiperazine product stream can be further diluted with water after leaving the distillation system. The further diluted dihydroxyethylpiperazine product stream may contain 5 to 80 wt% (e.g., 10 to 70 wt%, 20 to 60 wt%, 30 to 55 wt%, 35 to 50 wt%, 40 up to 45 wt.%, etc.) dihydroxyethylpiperazine.

The composition of the recycle piperazine stream can be adjusted, for example by adding or removing water, after it exits the distillation system and then loaded into the reactor as recycle piperazine. Thus, for example, the recycled piperazine stream may have the same ratio of piperazine to solvent as fresh piperazine fed to the reactor, or a similar ratio. For example, freshly prepared piperazine loaded into the reactor may contain from 30 to 99 wt.% (for example, from 40 to 98 wt.%, from 50 to 97 wt.%, from 55 to 96 wt.%, from 60 to 95 wt.%, 50 to 90 wt.%, 60 to 90 wt.%, 50 to 85 wt.%, 60 to 85 wt.%, 50 to 80 wt.%, 60 to 80 wt. .%, from 50 to 70 wt.%, from 60 to 70 wt.%, etc.) of piperazine in one or more solvents (for example, at least in water). Similarly, the recycled piperazine fed to the reactor may contain from 30 to 99 wt.% (for example, from 40 to 98 wt.%, from 50 to 97 wt.%, from 55 to 96 wt.%, from 60 to 95 wt.%, from 50 to 90 wt.%, from 60 to 90 wt.%, from 50 to 85 wt.%, from 60 to 85 wt.%, from 50 to 80 wt.%, from 60 to 80 wt. %, from 50 to 70 wt.%, from 60 to 70 wt.%, etc.) piperazine in one or more solvents (for example, at least in water).

Reagents such as freshly prepared piperazine and ethylene oxide can be loaded into the reactor at a temperature close to ambient temperature, for example, equal to from 20 to 25°C. The recycled piperazine can be cooled (eg temperatures below 80°C start temperature) and loaded into the reactor at a temperature close to ambient temperature, eg 20 to 25°C. In addition, freshly made piperazine, ethylene oxide and recycled piperazine can be loaded into the reactor at a pressure greater than atmospheric pressure, for example, at a pressure of 138 to 689 kPa, 138 to 552 kPa, 207 to 483 kPa, and the like. The temperature of the hydroxyethyl piperazine product stream exiting the distillation system may be elevated, for example, its temperature exceeds 60°C (for example, 65 to 150°C, 80 to 120°C, 80 to 110°C, etc. ).

Application of hydroxyethylpiperazine

Piperazines find practical applications in a wide range of applications, including the production of plastics, resins, and other industrial products. Piperazines can also be used in a variety of end products, such as those for improved oil and gas recovery, pesticides, automotive fluids, and pharmaceuticals. For example, hydroxyethylpiperazine can be used to absorb various contaminants often found in oil and gas streams. Typical pollutants include carbon dioxide, hydrogen sulfide and other sulfur pollutants. For example, hydroxyethylpiperazine can be used as a chemical solvent that absorbs contaminants.

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Examples

The following are approximate characteristics, features, parameters, etc. for illustrative working examples, comparative examples, as well as data used to obtain the results shown in working and comparative examples.

Materials used include the following: ethylene oxide (EO), piperazine (PIP) and a piperazine solution which contains 68% by weight of piperazine with the remainder being water as solvent and residual amounts of other impurities.

Working Examples 1 and 2 use a continuous reactor and a distillation procedure using multiple columns, and a recycle stream is used to produce hydroxyethylpiperazine as shown in FIG. 1. Working example 1 uses a continuous stirred tank reactor (CSR) and working example 2 uses a plug flow reactor (PRE). Comparative Example A uses a conventional semi-batch reactor and a distillation procedure using multiple columns, without using a recycle stream feed back to the semi-batch reactor to produce hydroxyethylpiperazine, as shown in FIG. 2.

The results presented in Table 1 below are based on the amount of pure piperazine, on a dry matter basis (i.e., excluding water contained in the feed as part of the piperazine solution) and assuming that the ethylene oxide sample contains 100 wt% EO. The HEP product stream leaving the distillation system is assumed to have a purity of about 99.3% by weight, with impurities being the remainder. The DIGEP product stream, DIGEP-OUTPUT, is expected to have a purity of about 43.7% by weight, with the remainder being water and impurities. For simulations, it is assumed that the DIGEP product stream is diluted with water to achieve a purity of 43.7 wt.%, in practice, dilution water can be added to the DIGEP product stream after it exits the distillation system. The results presented in table. 1 are based on obtaining equal amounts of HEP product (ie 47.6 million pounds) and on the assumption that the distillation systems are the same in the three examples.

The piperazine conversion is defined as the piperazine conversion taking into account the amount of pure piperazine loaded, excluding recycled piperazine. The yields of the products are determined as follows: the yield of HEP is defined as the number of moles of HEP obtained in terms of the number of moles of piperazine loaded into the reactor. In addition, the yield of DIGEP is defined as the number of moles of the obtained DIGEP in terms of the number of moles of piperazine loaded into the reactor. The total molar selectivity of HEP formation with respect to the selectivity of DIGEP formation means the number of moles of HEP obtained in terms of the number of moles of DIGEP obtained.

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Table 1

Working example 1 Working example 2 Comparative example A Raw material (tons) Ethylene oxide 13.2 9.7 13.2 Pure piperazine 20.4 16.9 28.1 Molar ratio when added to the reactor The ratio of the number of moles of ethylene oxide to the number of moles of pure piperazine * (excluding recycle flow) 1.37 1.23 1.01 The ratio of the number of moles of ethylene oxide to the total number of moles of pure piperazine (including recycle flow) 0.67 0.61 1.01 Product (tons) Product stream-HEP (HEP-OUT) (purity -99.3 wt.%) 21.6 21.6 21.6 Product stream-DIGEP (DIGEPVIVOD) (purity -43.7 wt.%)** 25.2 10.5 24.41 Piperazine Conversion Degree of conversion 0.97 0.98 0.70 Total output (product streams) gap (%) 69.9 84.7 50.9 DIGEP (%) 38.1 15.8 36.9 Molar selectivity The selectivity of the formation of HEP in relation to the selectivity of the formation DIGEP 2.6 6.3 2.7

* total number of moles of pure piperazine in terms of dry matter, excluding recycled piperazine;

* * Purity of 43.7 wt% based on dilution of the resulting DIGEP product stream with water

In table. 1 shows that using a recycled piperazine stream can allow the use of less pure piperazine required without compromising the purity of the HEP product stream, while unexpectedly providing higher piperazine conversion and overall yield of HEP product streams. In addition, in Working Example 1, it was found that the use of ERNP and a recycle stream can provide a significant improvement in overall yield and HEP selectivity relative to DHEP selectivity comparable to that achieved using the conventional semi-batch process in Comparative Example A. In Working Example 2 found that the use of RIV can provide a significant improvement in overall yield and HEP selectivity relative to DIGEP selectivity, and provide a better overall yield than using the conventional semi-batch process in Comparative Example and the ERNP reactor in Working Example 1.

The results are given in table. 1 were generated using commercially available simulation software, ASPENPLUS™ version 8.6 (available from Aspen Technology). Physical characteristics are determined using regression analysis of the data. The ASPEN software uses the Reactor Module Plug (for the RIV reactor), RCSTR (for the ERNP reactor), and rigorous calculation for the RADFRAC distillation module. The distillation procedure involves the use of multiple columns. Each column contains a sufficient number of stages, including plates or packing, to ensure the required purity of the separated product. Working pressure can match vacuum. In the examples, the following three columns are used in the distillation procedure:

a 17-stage vacuum (51 kPa) module designed to separate PIP and water from a crude reaction mixture, a 17-stage high vacuum (0.5 kPa) module designed to separate HEP from DIGEP, and a 12-stage module operating at atmospheric pressure is designed for PIP separation.

The capacity of the distillation system is typically limited by the capacity of the first column reboiler, with the top temperature maintained at 110°C. Upon receipt of the same amounts of HEP having the required purity, in all examples, the starting materials - 6043124 VA, the degree of conversion, the yield of the product and the selectivity are different. In all examples, for reliable comparison, the power of the first distillation column is constant and equal to 1.52 kJ/h. The flows obtained using the ASPEN model are presented in Table. 2, 3 and 4 for working examples 1 and 2 and comparative example A, respectively.

For working examples 1 and 2, the parameters used for simulation are presented in the tables below. 2 and 3, respectively. In table. 2 and 3: EO means ethylene oxide loaded into the reactor and PIP means pure piperazine loaded into the reactor. PIP-RC means a recycle piperazine stream that is diluted with water to provide a piperazine concentration of about 68 wt.%, thus it means a stream that enters the reactor. HEP-OUT means a stream of hydroxyethylpiperazine leaving the distillation system having a purity of greater than 99% by weight. DIGEP-OUT means the stream of dihydroxyethylpiperazine leaving the distillation system, diluted with water to provide a purity of 43.7 wt.%. HEP-WITH pressure means the pressure in the distillation column in which the hydroxyethyl piperazine is separated from the dihydroxyethyl piperazine. The DIGEP-OUT pressure means the pressure at which the DIGEP stream is pumped until it is diluted with a purity of 43.7%.

table 2

EO-INPUT PIP- ENTER pipRC GAP CONCLUSION DIGEP-OUTPUT Molar flow (kmol/h) Water 0 7.18 7.95 <0.01 9.87 Pure piperazine 0 3.19 3.38 0.02 <0.01 GEO 0 0 0.02 2.22 0.10 DIGEP 0 0 <0.01 <0.01 0.85 Ethylene oxide 4.02 0 0 0 0 Mass flow (kg/h) Water 0 129.29 143.16 <0.01 177.80 Pure piperazine 0 247.75 291.13 1.87 <0.01 GEO 0 0 3.00 288.51 12.87 DIGEP 0 0 0.06 0.03 148.00 Ethylene oxide 176.90 0 0 0 0 Mass fraction Water 0 0.32 0.33 <0.01 0.53 Pure piperazine 0 0.68 0.66 0.01 <0.01 GEO 0 0 0.01 0.99 0.04 DIGEP 0 0 <0.01 <0.01 0.44 Ethylene oxide 1.00 0 0 0 0 Total Total flow (kmol/h) 4.02 10.37 11.35 2.24 10.82 Total flow (kg/h) 176.90 404.05 437.35 290.41 338.68 Full s consumption (m / h) 0.20 0.39 0.45 0.29 0.33 Temperature (°C) 20.0 20.0 96.8 92.3 67.0 Pressure (kPa) 330.9 330.9 330.9 0.4 101.3

For working example 2, the parameters used for simulation are shown in the table below. 3.

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Table 3

eo input PIP- ENTER pipRC GAP CONCLUSION DIGEP-OUTPUT Molar flow (kmol/h) Water 0 7.43 7.84 <0.01 5.15 Pure piperazine 0 3.30 3.40 0.03 <0.01 GEO 0 0 0.03 2.78 0.05 DIGEP 0 0 <0.01 <0.01 0.44 Ethylene oxide 3.72 0 0 0 0 Mass flow (kg/h) Water 0 133.89 141.21 <0.01 92.70 Pure piperazine 0 284.52 292.93 2.16 <0.01 GEO 0 0 3.63 361.86 6.71 DIGEP 0 0 0.03 0.04 77.16 Ethylene oxide 163.75 0 0 0 0 Mass fraction Water 0 0.32 0.32 <0.01 0.52 Pure piperazine 0 0.68 0.67 0.01 <0.01 GEO 0 0 <0.01 0.99 0.04 digap 0 0 <0.01 <0.01 0.44 Ethylene oxide 1.00 0 0 0 0 Total Total flow (kmol/h) 3.72 10.74 11.27 2.80 5.64 Total flow (kg/h) 163.75 418.41 437.80 364.06 176.57 Full flow (m ³ / h) 0.19 0.40 0.45 0.36 0.17 Temperature (°C) 20.0 20.0 97.4 92.7 67.6 Pressure (kPa) 330.9 330.9 330.9 0.4 101.3

For Comparative Example A, the parameters used for simulation are shown in Table 1 below. 4. NGEP-OUT means the crude hydroxyethylpiperazine stream exiting the reactor and entering the distillation system. PIP-RC means the piperazine stream leaving the distillation system, which in Comparative Example A is not recycled back to the reactor. HEP-BOD means the hydroxyethyl piperazine stream exiting the distillation system, and DIHEP-BOD means the dihydroxyethyl piperazine stream leaving the distillation system diluted with water to a purity of 43.7% by weight.

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Table 4

| ngep* PIP-RC GAP CONCLUSION DIGEP-OUTPUT Molar flow (kmol/h) Water 14.16 4.02 0 13.74 Pure piperazine 1.71 1.71 <0.01 <0.01 GEO 3.40 0.05 3.21 0.14 DIGEP 1.18 <0.01 <0.01 1.18 Mass flow (kg/h) Water 255.14 72.34 0 247.57 Pure piperazine 147.29 146.99 <0.01 <0.01 GEO 442.77 7.07 417.79 17.92 DIGEP 206.20 0.09 0.04 206.07 Mass fraction Water 0.24 0.32 <0.01 0.52 Pure piperazine 0.14 0.65 <0.01 <0.01 GEO 0.42 0.03 0.99 0.04 DIGEP 0.20 <0.01 <0.01 0.44 Total Total flow (kmol/h) 20.46 5.78 3.21 15.06 Total flow (kg/h) 1051.41 226.48 417.83 471.56 Full flow (m/h) 0.99 0.23 0.41 0.46 Temperature (°C) 60.0 98.1 96.9 68.4 Pressure (kPa) 273.7 102.7 0.4 101.3

* the composition of the NGEP flow is determined at the outlet of the semi-batch reactor

In addition, for comparative example And the parameters of the reaction in a semi-batch mode, used for modeling, are presented in the following table. 5.

____________________________________________________ Table 5

Pure piperazine (kg) 28068 EO (kg) 13154 The duration of the reaction carried out in a semi-batch mode (h) 2.5 Product-NGEP (kg) 54431

CLAIM

Claims (8)

1. Conducted in a continuous mode, the method of obtaining N-(2-hydroxyethyl)piperazine, the method includes loading pure piperazine, recycled piperazine and ethylene oxide into a reactor to obtain crude N-(2-hydroxyethyl)piperazine, the reactor is a tank reactor with continuous stirring or a reactor with perfect displacement; moreover, the ratio of the number of moles of ethylene oxide to the number of moles of pure piperazine added to the reactor is more than 1.01; and continuously feeding the crude N-(2-hydroxyethyl)piperazine exiting the reactor into a distillation system which includes at least one distillation column, the distillation system producing at least a recycle piperazine stream and an N-(2hydroxyethyl)piperazine stream , the recycle piperazine stream contains recycle piperazine, which is loaded into the reactor to obtain crude N-(2-hydroxyethyl)piperazine, and the N-(2hydroxyethyl)piperazine stream contains at least 60 wt.% N-(2-hydroxyethyl)piperazine in terms of the total weight of the N-(2-hydroxyethyl)piperazine stream. 2. The method of claim 1 wherein the ratio of moles of ethylene oxide to total moles of piperazine, including moles of pure piperazine and moles of recycled piperazine, is between 0.10 and 1.01. 3. Process according to any one of claims 1, 2, wherein the recycle piperazine stream contains from 30 to 99% by weight of piperazine. 4. The method according to any one of claims 1 to 3, wherein the distillation system comprises three distillation columns, the first distillation column receives the crude N-(2hydroxyethyl)piperazine leaving the reactor, the second distillation column receives the overhead stream leaving the first distillation column, and water is separated from piperazine in it, and the third distillation column receives the bottom stream leaving the first distillation - 9 043124 columns, and N-(2-hydroxyethyl)piperazine is separated from N,N'-di(2-hydroxyethyl)piperazine. 5. The method according to any one of paragraphs. 1-4, in which in the distillation system an N,N'-di(2-hydroxyethyl)piperazine stream is additionally obtained, which contains at least 35 wt.% N,N'-di(2hydroxyethyl)piperazine, calculated on the total mass of the N stream ,N'-di(2-hydroxyethyl)piperazine. 6. The process of claim 5, wherein in the distillation system, the recycle piperazine stream is separated before the N,N'-di(2-hydroxyethyl)piperazine stream and the N-(2-hydroxyethyl)piperazine stream are separated from each other. 7. Process according to any one of claims 1 to 6, wherein the recycle piperazine stream, diluted with water, is continuously fed directly into the reactor. 8. Process according to any of claims 1 to 7, wherein the reactor is a plug flow reactor.