Method for purifying n-methyl-2-pyrrolidone using a heat pump

Abstract

The present invention relates to a method for purifying N-methyl-2-pyrrolidone (NMP), the method comprising (i) introducing a raw material stream comprising NMP into a column, and heating the raw material stream for separation into a stream containing NMP, a gaseous top stream, and a bottom stream; (ii) compressing the gaseous top stream obtained in (i), obtaining a compressed gaseous top stream; (iii) transferring heat from the compressed gaseous top stream to a process stream of a chemical process, obtaining a cooled and at least partially condensed top stream; (iv) expanding the cooled and at least partially condensed top stream, resulting in an expanded top stream; and (v) returning at least part of the expanded top stream to the column according to (i). A comparatively significant amount of steam can be saved using the method according to the invention.

Description

Method for the purification of N-methyl-2-pyrrolidone using a heat pump TECHNICAL AREA The present invention relates to a process for the purification of N-methyl-2-pyrrolidone (also known as 1-methylpyrrolidin-2-one, or NMP for short) using a heat pump. INTRODUCTION N-Methyl-2-pyrrolidone is produced on an industrial scale by reacting γ-butyrolactone (hereinafter also referred to as gamma-butyrolactone) with methylamine at temperatures of 250 to 400 °C and pressures of 60 to 120 bar in adiabatic tubular reactors. The reaction is exothermic. The product mixture is then depressurized and separated by distillation in appropriate distillation columns. EP 4091688 A1 relates to a plant and process for the purification of recovered N-methylpyrrolidone (NMP). WO 2021 / 093918 A1 concerns separation devices and separation processes for separating biogenic, semi-synthetic and / or synthetic mixtures into their solid, liquid and gaseous components with heat recovery. US 2013 / 0267751 A1 relates to a process and apparatus for separating 1,2,4-trimethylbenzene (also known as pseudocumene) from a mixture comprising aromatic hydrocarbons. CN 219558744 U relates to an NMP distillation apparatus for use in a polysulfone manufacturing process (see Figure 1). According to Figure 1, this apparatus would have a distillation tower 1 comprising a side outlet for an NMP gas phase, a vapor outlet at the top, and a liquid outlet at the bottom. The vapor outlet would be connected via a compressor 2 to a falling film evaporator 3. The falling film evaporator 3 would be used to transfer heat from the compressed overhead stream to the bottom stream. CN 116947728 A relates to a method for the purification of NMP (see claim 1). According to Figure 1, a vapor stream would be separated from a distillation apparatus for the purification of NMP and, after compression, introduced into a heat exchanger. The resulting cooled stream would be returned to the distillation apparatus. Against this background, it can be considered an object of the present invention to provide, in particular, a method for purifying NMP that is comparatively energy- and resource-efficient, and in particular enables stable operation of the method. Furthermore, it can be considered an object of the present invention to provide a method for purifying NMP that, in particular, enables a reduction in CO2 emissions. Finally, it was an object of the present invention to provide a method for producing NMP in which the described purification method is implemented. DETAILED DESCRIPTION Surprisingly, it was discovered that the column used for purifying NMP can be heated by introducing a compressor and an evaporator. Specifically, the vapors generated at the top of the column can be directed via an intermediate compressor into the evaporator, where they condense and heat the column. The resulting liquid condensate from the evaporator can then be routed through an expansion valve to a top condenser. Furthermore, an additional evaporator can be used to heat the feed stream, which can also be used, for example, to start up the column and to compensate for control fluctuations. The unit bara refers to absolute pressure and the unit barg to relative pressure, where 1 bar equals 10 5 Pa corresponds. The present invention is further characterized by the following embodiments, including the individual and specific combinations of embodiments indicated by the respective dependencies. It should be noted in particular that in each case where a specific number of embodiments is defined, for example in the context of a term such as "method according to one of embodiments 1 to 4", each embodiment in this set is explicitly disclosed to the person skilled in the art, which means that the formulation of this term is to be understood by the person skilled in the art as synonymous with "method according to one of embodiments 1, 2, 3 and 4".Furthermore, it is expressly pointed out that the following list of exemplary embodiments constitutes an adequate, structured part of the general description, which is directed towards preferred aspects of the present invention and thus appropriately supports, but does not constitute, the claims of the present invention. Therefore, the present invention relates to a process for the purification of N-methyl-2-pyrrolidone (NMP), the process comprising (i) Introducing a feedstock stream comprising NMP, preferably the dehydrated product stream obtained in (b), into a column and heating the feedstock stream to separate into an NMP-containing stream, a gaseous top stream, and a bottom stream, (ii) Compressing the gaseous overhead stream obtained in (i), obtaining a compressed gaseous overhead stream, (iii) Transferring heat from the compressed gaseous overhead stream to a process stream of a chemical process, preferably to a process stream of this process or of another chemical process, more preferably to the product stream obtained in (a), to the bottom stream obtained in (i), or to the product stream obtained in (a) and to the bottom stream obtained in (i), obtaining a cooled and at least partially condensed overhead stream, (iv) Relaxing the cooled and at least partially condensed head stream, obtaining a relaxed head stream, (v) Returning at least part of the relaxed overhead flow to the column according to (i). There is no restriction regarding the number of process steps, such as (i), (ii), (iii), (iv), and (v) in the aforementioned embodiment. Accordingly, the process may include further process steps, such as (vi), (vii), and (viii) in another embodiment. Furthermore, it is possible that a process step, such as (iii), may include further process steps, such as (iii.a), (iii.b), and (iii.c) in another embodiment. Furthermore, one or more process steps can be performed multiple times; for example, steps (i), (ii), and (iii) can be performed several times in succession in this order before step (iv) is performed. The preferred order of the process steps is (i), (ii), (iii), (iv), (v) as defined in the following embodiment 1, wherein process steps (a) and (b), as defined in the following embodiment 46, are particularly preferably performed in this order before process step (i). With regard to the composition of the raw material stream introduced into the column in (i), it is preferred that it comprises NMP from 95.0 to 99.9 wt%, more preferably from 97.6 to 99.7 wt%, more preferably from 98.6 to 99.6 wt%. Regarding the composition of the raw material stream introduced into the column in (i), it is further preferred that it comprises 0.01 to 0.10 wt%, more preferably 0.03 to 0.08 wt%, more preferably 0.04 to 0.07 wt% of H2O. With regard to the composition of the raw material stream introduced into the column in (i), it is further preferred that it comprises 0.1 to 1.7 wt%, more preferably 0.3 to 1.4 wt%, more preferably 0.5 to 1.2 wt% of high-boiling compounds. wherein the high-boiling compounds preferably comprise one or more of gamma-butyrolactone, oligomers of gamma-butyrolactone, and hydroxybutyric acid. Regarding the conditions under which raw material stream is introduced into the column, it is preferred that it is introduced into the column at a mass flow rate in the range of 100 to 10,000 kg / h, more preferably from 3,500 to 5,500 kg / h, and more preferably from 4,000 to 4,750 kg / h. With regard to the conditions under which raw material stream is heated in (i), it is preferred that the temperature in the column according to (i) is in a range of 100 to 140 °C, more preferably 105 to 135 °C, more preferably 110 to 130 °C, more preferably 112 to 128 °C. With regard to the conditions under which raw material stream is heated in (i), it is preferred that the pressure in the column according to (i) is in a range of 40 to 110 mbara, more preferably 50 to 100 mbara, more preferably 55 to 90 mbara, more preferably 60 to 84 mbara. There is no restriction regarding the column in (i) provided it is suitable for heating and separating the raw material stream. Preferably, the column according to (i) is a distillation column, wherein the column preferably comprises one or more, more preferably three, packing elements, wherein the one or more packing elements are independently of one another and preferably have low pressure loss, wherein the one or more packing elements more preferably independently comprise one or more liquid collectors and liquid distributors, and wherein the one or more packing elements are more preferably independently of one another sheet metal packings or wire mesh packings. With regard to the composition of the gaseous headstream obtained in (i), it is preferred that it comprises 95.0 to 99.8 wt%, more preferably 97.8 to 99.6 wt%, more preferably 98.6 to 99.4 wt% of NMP. Regarding the composition of the gaseous overhead stream obtained in (i), it is further preferred that this overhead stream comprises 0.1 to 1.5 wt%, more preferably 0.3 to 1.3 wt%, more preferably 0.5 to 1.2 wt% of H2O. With regard to the ratio of the mass flow rate of the gaseous overhead stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column, it is preferred that this ratio is in the range of 0.95:1 to 1.20:1, more preferably from 1.00:1 to 1.15:1, more preferably from 1.05:1 to 1.09:1. With regard to the NMP-containing stream obtained in (i), it is preferred that it comprises 99.75 to 99.9999 wt%, more preferably 99.80 to 99.999 wt%, more preferably 99.85 to 99.99 wt% of NMP. With regard to the NMP-containing stream obtained in (i), it is further preferred that it comprises H2O of greater than 0 to 150 ppm, more preferably of 10 to 110 ppm, more preferably of 15 to 100 ppm. With regard to the NMP-containing stream obtained in (i), it is further preferred that it be obtained in a side draw of the column according to (i). With regard to the ratio of the mass flow rate of the NMP-containing stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column, it is preferred that this ratio is in the range of 0.75:1 to 1.10:1, more preferably from 0.85:1 to 1.00:1, more preferably from 0.90:1 to 0.94:1. With regard to the ratio of the mass flow rate of the sump stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column, it is preferred that this ratio is in the range of 0.001 :1 to 0.06:1, preferably from 0.01 :1 to 0.05:1, and more preferably from 0.02:1 to 0.04:1. With regard to the swamp stream obtained in (i), it is preferred that it comprises 60 to 72 wt%, more preferably 62 to 70 wt%, more preferably 64 to 68 wt% of NMP. With regard to the bottom stream obtained in (i), it is further preferred that it comprises 15 to 55 wt%, more preferably 25 to 45 wt%, more preferably 29 to 39 wt% of high-boiling compounds, wherein the high-boiling compounds preferably comprise 1,4-butanediol. With regard to heating according to (i) by means of one or more, preferably two, evaporators, it is preferred that the one or more evaporators are selected independently of each other, preferably from the group consisting of natural circulation evaporators and falling film evaporators. With regard to the temperature difference between the gaseous top stream obtained in (i) and the bottom stream obtained in (i), it is preferred that this is in the range of 10 to 20 °C, more preferably 12 to 18 °C, and more preferably 13 to 16 °C. With regard to the gaseous headstream obtained in (i) in (ii), it is preferred that it be compressed to a pressure in the range of 150 to 450 mbara, more preferably from 170 to 350 mbara, more preferably from 180 to 290 mbara, more preferably from 190 to 260 mbara. With regard to the compression according to (ii) it is preferred that this be carried out by means of a compressor or a blower, preferably a multi-stage blower. With regard to the compressed gaseous headstream obtained in (ii), it is preferred that it has a temperature in the range of 90 to 190 °C, more preferably 100 to 180 °C, more preferably 111 to 172 °C, more preferably 147 to 172 °C. With regard to the sump flow obtained according to (i), it is preferred that it be split into a returnable sump flow and an excess sump flow. If the bottom stream obtained according to (i) is divided into a recyclable bottom stream and an excess bottom stream, it is preferred that heat is transferred from the compressed overhead stream to the recyclable bottom stream according to (iii), obtaining a heated recyclable bottom stream, wherein the heated recyclable bottom stream is recirculated into the column according to (i). With regard to the transfer of heat according to (iii) it is preferred that this be done by means of an evaporator, wherein the evaporator is preferably selected from the group consisting of natural circulation evaporators and falling film evaporators. With regard to the cooled and at least partially condensed overhead stream obtained in (iii), it is preferred that it has a temperature in the range of 130 to 156 °C, more preferably 135 to 151 °C, and more preferably 140 to 146 °C. With regard to the cooled and at least partially condensed overhead stream obtained in (iii), it is preferred that it has a pressure in the range of 150 to 450 mbara, more preferably 170 to 350 mbara, more preferably 180 to 290 mbara, more preferably 190 to 260 mbara. With regard to the chemical process, it is preferred that it includes the production of NMP. With regard to the process stream in (iii), it is preferred that it includes NMP. With regard to the process stream in (iii), it is further preferred that it comprises H2O. If the process stream in (iii) includes H2O, it is further preferred that the H2O-containing process stream is obtained in gaseous form, i.e., as water vapor, by transferring heat according to (iii). The water vapor can also be generated in a vacuum. The obtained water vapor is preferably further compressed. This can be done by means of one or more compressors, preferably a cascade of compressors. Positive displacement machines and / or turbomachines, for example, can be used as compressors. Screw compressors, radial blowers, radial turbo compressors (such as geared compressors), and / or axial turbo compressors are used. Compression preferably includes the addition of water to spray off the steam after a compressor with the longest possible inlet section. Preferably, the water is sprayed to accelerate evaporation and prevent the formation of droplet streaks, as water droplets can impair the function of the compressor blades. In particular, the blades of an axial turbo compressor should not come into contact with water droplets. Alternatively, water can also be sprayed for cooling purposes, for example, if screw compressors and / or radial blowers are used. In this way, the water vapor can be compressed to a pressure in the range of 1 to 120 barg at a temperature in the range of 127 to 450 °C, preferably to a pressure in the range of 1.5 to 2.0 barg at a temperature in the range of 127 to 200 °C, a pressure in the range of 4.0 to 5.8 barg at a temperature in the range of 151 to 200 °C, a pressure in the range of 15.0 to 17.8 barg at a temperature in the range of 201 to 250 °C, a pressure in the range of 40 to 49 barg at a temperature in the range of 250 to 300 °C, or a pressure in the range of 100 to 117 barg at a temperature in the range of 310 to 450 °C. Compression to a pressure in the range of 4.0 to 5.8 barg is comparatively more economical than compression to a pressure in the range of 15.0 to 17.8 barg. Steam at a pressure in the range of 40 to 49 barg or in the range of 100 to 117 barg can be generated by the compression described; however, generation using waste heat from a cracker or similar processes is comparatively more energy-efficient. The compressed steam can be fed into a steam network, preferably in one of the pressure and temperature ranges described herein. The compressed steam can be used in the plant used for the purification of N-methyl-2-pyrrolidone (NMP) or in spatially adjacent plants for (accompanying) heating of equipment and pipelines (e.g., for frost protection in winter), preferably at a pressure in the range of 1.5 to 2.0 barg. Alternatively, the compressed steam can be used in spatially adjacent plants for heating evaporators and reactors (e.g., to reduce steam consumption from the network). Often, compression of the steam to, for example, 3 barg is sufficient. In another alternative, the compressed steam can be mixed with green steam, even at different pressure levels. The "green steam" produced via waste heat and with the aid of green electrical energy in compressors can then be allocated to other plants or their products for energy balance purposes when connected via pipelines or a steam network.This can reduce the Product Carbon Footprint (PCF) of products manufactured in plants that do not generate green steam. With regard to the relaxation according to (iv), it is preferred that this be done by means of a relaxation valve. With regard to the overhead stream cooled and at least partially condensed in (iv), it is preferred that it be depressurized to a pressure in the range of 30 to 90 mbara, more preferably 40 to 80 mbara, more preferably 50 to 70 mbara, more preferably 55 to 65 mbara. With regard to the relaxed head current obtained in (iv), it is preferred that it has a temperature in the range of 88 to 104 °C, more preferably of 83 to 99 °C, and more preferably of 88 to 94 °C. Preferably, a portion of the relaxed headstream obtained in (iv) is liquid and a portion of the relaxed headstream obtained in (iv) is gaseous, wherein more preferably 81 to 99 wt%, more preferably 85 to 95 wt%, more preferably 88 to 92 wt% of the relaxed headstream obtained in (iv) are liquid, and wherein more preferably 1 to 19 wt%, more preferably 5 to 15 wt%, more preferably 8 to 12 wt% of the relaxed headstream obtained in (iv) are gaseous. With regard to the method, it is preferred that it further comprises (iv.1 ) cooling the relaxed headstream obtained in (iv) after (iv) and before (v). If the further process step (iv.1 ) is carried out, it is preferred that the cooling according to (iv.1 ) is carried out by means of a condenser. If the further process step (iv.1) is carried out, it is further preferred that in (iv.1) the expanded overhead flow is cooled to a temperature in the range of 88 to 104 °C, more preferably from 83 to 99 °C, more preferably from 88 to 94 °C. If the further process step (iv.1) is carried out, it is further preferred that the relaxed headstream obtained in (iv.1) has a pressure in the range of 30 to 90 mbara, more preferably 40 to 80 mbara, more preferably 50 to 70 mbara, more preferably 55 to 65 mbara. If the further process step (iv.1 ) is carried out, it is further preferred that part of the relaxed overhead stream obtained in (iv.1) is liquid and part of the relaxed overhead stream obtained in (iv.1) is gaseous. If part of the relaxed overhead stream obtained in (iv.1) is liquid and part of the relaxed overhead stream obtained in (iv.1) is gaseous, it is particularly preferred that in (v) the liquid part of the relaxed overhead stream obtained in (iv) is recycled to the column according to (i). With regard to the relaxed headstream obtained in (iv) or (iv.1 ), it is preferred that it has a mass flow rate in the range of 100 to 10,000 kg / h, preferably 4,000 to 5,500 kg / h, more preferably 4,500 to 5,000 kg / h. With regard to the relaxed overhead current obtained in (iv) or (iv.1), it is further preferred that 50 to 100 wt%, more preferably 80 to 98 wt%, more preferably 88 to 96 wt% of this current be recycled into the column according to (i). With regard to the ratio of the mass flow rate of the portion of the relaxed overhead stream recycled to the column according to (v) to the mass flow rate of the raw material stream introduced into the column, it is preferred that this ratio lies in the range of 0.94:1 to 1.10:1, more preferably from 0.98:1 to 1.06:1, more preferably from 1.01:1 to 1.03:1. With regard to the portion of the expanded overhead stream returned to the column according to (v), it is preferred that this portion has a temperature in the range of 78 to 125 °C, preferably 83 to 120 °C, more preferably 88 to 115 °C. With regard to the portion of the relaxed overhead stream returned to the column according to (v), it is preferred that this has a pressure in the range of 40 to 90 mbara, preferably 50 to 80 mbara, more preferably 55 to 75 mbara, more preferably 55 to 65 mbara. With regard to the portion of the relaxed overhead stream returned to the column according to (v), it is further preferred that this portion be liquid. With regard to the procedure, it is preferred that it further includes (i) (a) Reacting a reactant stream comprising gamma-butyrolactone (GBL) and monomethylamine (MMA) under reaction conditions to obtain a product stream comprising NMP and H2O, and (b) Introducing the product stream obtained in (a) into a column, and heating the product stream to separate it into a dehydrated product stream and an H2O-containing stream, wherein the process is for the production and purification of N-methyl-2-pyrrolidone (NMP). Provided that the further process steps (a) and (b) are carried out, it is preferred that the reactant stream has a molar ratio, GBL:MMA, of gamma-butyrolactone to monomethylamine in the range of 0.9:1 to 1.1:1, preferably from 0.99:1 to 1.01:1. Provided that the further process steps (a) and (b) are carried out, it is still preferred that the conversion according to (a) takes place in a tubular reactor. Provided that the further process steps (a) and (b) are carried out, it is further preferred that the reaction conditions according to (a) include heating the reactant stream to a temperature in the range of 320 to 400 °C, more preferably from 340 to 380 °C, more preferably from 350 to 370 °C. Provided that the further process steps (a) and (b) are carried out, it is further preferred that the reaction conditions according to (a) include applying a pressure in the range of 70 to 110 bara, more preferably from 80 to 100 bara, more preferably from 85 to 95 bara. Provided that the further process steps (a) and (b) are carried out, it is still preferred that the reaction conditions include an adiabatic conversion in (a). Provided that the further process steps (a) and (b) are carried out, it is further preferred that the product stream introduced into the column according to (b) has a temperature in the range of 125 to 195 °C, more preferably 145 to 175 °C, and more preferably 155 to 165 °C. Provided that the further process steps (a) and (b) are carried out, it is further preferred that the product stream introduced into the column according to (b) has a pressure in the range of 800 to 1,000 mbara, more preferably from 825 to 975 mbara, more preferably from 900 to 950 mbara. Provided that the further process steps (a) and (b) are carried out, it is further preferred that the heating according to (b) is carried out by means of an evaporator, wherein the evaporator is preferably selected from the group consisting of natural circulation evaporators and falling film evaporators. Provided that the further process steps (a) and (b) are carried out, it is further preferred that the temperature in the column according to (b) is in a range of 95 to 240 °C, more preferably from 100 to 235 °C, and more preferably from 105 to 230 °C. Provided that the further process steps (a) and (b) are carried out, it is further preferred that the pressure in the column according to (b) is in a range of 600 to 800 mbara, more preferably from 625 to 775 mbara, more preferably from 650 to 750 mbara. The present invention further relates to a target product that can be obtained or is attainable by a method according to the present invention. The publication “Chemical Compounds”; Issue 684; paragraphs

[1000] until

[8005] ; ISSN: 2198-4786; published on February 12, 2024, is referred to as Reference RF1, which is incorporated herein in its entirety by reference. Preferably, the target product is a product as described in Reference RF1 in paragraphs

[1000] to

[8005] described. Preferably the The process described here is also a process for manufacturing a product, preferably the target product. The conversion step for obtaining the target product preferably comprises one or more steps as described below and can be carried out by conventional methods known to a person skilled in the art. The conversion step preferably comprises one or more of the following: recycling, preferably depolymerization, gasification, pyrolysis, and / or steam cracking; and / or purification, preferably crystallization, (solvent) extraction, distillation, evaporation, hydrotreating, absorption, adsorption, and / or ion exchange treatment; and / or processing, preferably foaming, synthesis, chemical conversion, polymerization, and / or compounding; and / or shaping, preferably foaming, extrusion, and / or forming; and / or finishing, preferably coating and / or smoothing. Additionally, the one or more steps in Reference RF1 are described in the paragraphs below.

[1000] to

[8005] described in detail. The term "building block," as used here, encompasses compounds that exist in a gaseous or liquid state under standard conditions of 0°C and 0.1 MPa. Building blocks are typically used in the chemical industry to form secondary products that exhibit higher structural complexity and / or a higher molecular weight than the building block on which the secondary product is based. The building block is preferably selected from the group consisting of hydrogen, carbon monoxide, carbon dioxide, ethylene oxide, ethylene glycols, synthesis gas consisting of a mixture of hydrogen and carbon monoxide, alkanes, alkenes, alkynes, and aromatic compounds. The alkanes, alkenes, alkynes, and aromatic compounds include, in particular, those with 1 to 12 carbon atoms. The term "monomer," as used here, encompasses molecules that can react with one another to form polymers by polymerization. The monomer is preferably selected from the group consisting of (meth)acrylic acid, salts of (meth)acrylic acid, in particular sodium, potassium, and zinc salts, (meth)acrolein, and (meth)acrylates. (Meth)acrylates with 1 to 22 carbon atoms are preferred, especially those with 1 to 8 carbon atoms. The terms (meth)acrylic acid, (meth)acrolein, or (meth)acrylate refer to acrylic acid, acrolein, or acrylate, respectively, and to methacrylic acid, methacrolein, or methacrylate, respectively. Furthermore, the monomer can be selected from hexamethylenediamine (HMD) and adipic acid. The building block can also be an intermediate compound. The term "intermediate compound," as used here, encompasses organic reagents used to form compounds of higher molecular complexity. The intermediate compound can be selected, for example, from the group consisting of phosgene, polyisocyanates, and propylene oxide. The polyisocyanates are, in particular, aromatic di- and polyisocyanates, preferably toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate. cyanate (MDI). The building block and the monomer, as well as typical conversion steps for obtaining the building block or monomer, are described in the following paragraphs.

[1000] to

[1012] The reference RF1 is described in more detail. The term "Polymer A", as used here, includes thermoplastic polymers, e.g. polyamide or thermoplastic polyurethane, thermosetting polymers, e.g. polyurethane, elastomers, e.g. polybutadiene, or a copolymer or a mixture thereof, and is further defined in the following paragraphs.

[2001] until

[2007] defined by reference RF1. The term "polymer composition A", as used here, includes all compositions containing a polymer as described above and one or more additives, e.g., reinforcing agents, colorants, modifiers and / or flame retardants, and is further specified in paragraph

[2008] defined by reference RF1. The term "polymer product A", as used here, encompasses a product containing polymer A and / or polymer composition A as described above and is further specified in the paragraphs

[2009] and

[2010] defined by reference RF1. The steps for obtaining the polymer, preferably polymer A, the polymer composition, preferably polymer composition A, or the polymer product, preferably polymer product A, are described in more detail in paragraph

[2011] described in reference RF1. The term "polymer for industrial use" includes rheological polymers, polycarboxylates, alkoxysilated polyalkylenamines, alkoxysilated polyalkylenimines, polyether-based polymers, color inhibition and dirt removal or cleaning polymers, which are described in the paragraphs

[3035] until

[3044] are defined in more detail by the reference RF1. The term "surfactant for industrial use" includes non-ionic, anionic and amphoteric surfactants for industrial use, which are described in the paragraphs

[3008] until

[3034] are defined in more detail by reference RF1. The term "descaling agents for industrial use" includes non-phosphate-based builders (NPB) and phosphonates (CoP), which are described in the paragraphs

[3001] until

[3005] are described in more detail in reference RF1. The term "biocide for industrial use" refers to a chemical compound that kills microorganisms or inhibits their growth or reproduction, as described in the paragraphs

[3006] until

[3007] further defined by the reference RF1. The term "solvents for industrial use" includes alkylamides, alkylactamides, alkyl esters, lactate esters, alkyl diesters, cyclic alkyl diesters, cyclic carbonates, and aromatic aldehydes. and aromatic esters, which are in the paragraphs

[3045] until

[3055] are defined in more detail by the reference RF1. The term "dispersants for industrial use" includes anionic and non-ionic dispersants for industrial use, which are described in the paragraphs

[3056] until

[3058] are defined in more detail by the reference RF1. The term "composition and / or formulation thereof" in relation to polymers for industrial use, surfactants for industrial use, descaling agents for industrial use and / or biocides for industrial use refers to compositions for industrial use and / or products for institutional use and / or textile and household care products and / or personal care products which are listed in paragraph

[3059] The conversion steps for the production of the polymer for industrial use, the surfactant for industrial use, the descaling agent for industrial use and / or the biocide for industrial use are defined in paragraph

[3060] Reference RF1 is defined in more detail. The conversion steps for the manufacture of the composition for industrial use or the formulation of the polymer for industrial use, the surfactant for industrial use, the descaling agent for industrial use and / or the biocide for industrial use are described in paragraph

[3061] defined in more detail by reference RF1. The term "plant protection product composition" generally refers to a composition that includes an agrochemically active ingredient and at least one agrochemical formulation additive. Examples of plant protection product compositions, active ingredients, and additives are given in paragraph [number].

[4001] The reference RF1 describes it in more detail. The plant protection product composition can be in any conventional formulation. The plant protection product compositions are manufactured using conventional methods, e.g., as described in the publications by Mollet and Grubemann, Formulation technology, Wiley VCH, Weinheim, 2001; or Knowles, New developments in crop protection product formulation, Agrow Reports DS243, T&F Informa, London, 2005. The conversion steps for the production of the agrochemically active ingredients and additives can be carried out analogously to the manufacturing steps of their analogues based on petrochemical or other precursors not obtained through recycling processes.Furthermore, conversion to compounds mentioned in the sections "Polymer" and "Cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, other cosmetic ingredients or compositions or formulations thereof" can take place as described in those sections and the corresponding paragraphs in Reference RF1. The term "active pharmaceutical agents and / or intermediates thereof" encompasses substances that produce a pharmacological effect or other direct action in the diagnosis, cure, alleviation, treatment, or prevention of disease, or that affect the structure or function of the body. Intermediates thereof are isolated products that arise during a multi-step synthesis route of an active pharmaceutical agent. The term "pharmaceutical excipients" encompasses compounds or mixtures of compounds used in compositions for various pharmaceutical applications that are not themselves substantially pharmaceutically active. Active pharmaceutical ingredients and / or intermediates thereof, as well as pharmaceutical excipients, are discussed in paragraph [number].

[5001] The reference RF1 defines in more detail. The conversion steps for the production of the active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients can be carried out by one or more synthesis steps and can be performed using conventional synthesis and techniques known to a person skilled in the art. The terms animal feed additives, food additives for humans and food supplements include vitamins, provitamins and active metabolites thereof, including intermediates and precursors, in particular vitamins A, B, E, D, K and their esters such as acetate, propionate, palmitate esters or alcohols thereof such as retinol or their salts, as well as any combinations thereof; tetraterpenes, in particular isoprenoids such as carotenoids and xanthophylls, including their intermediates and precursors, as well as mixtures and derivatives thereof, in particular beta-carotene, canthaxanthin, citranaxanthin, astaxanthin, zeaxanthin, lutein, lycopene, apo-carotenoids and any combinations thereof;Organic acids, in particular formic acid, propionic acid and their salts such as sodium, calcium or ammonium salts and any combinations thereof, such as, but not limited to, mixtures of formic acid and sodium formate, propionic acid and ammonium propionate, formic acid and propionic acid, formic acid and sodium formate and propionic acid, propionic acid and sodium propionate and formic acid and sodium formate; glycerides of carboxylic acids and short-chain and medium-chain fatty acids, conjugated linoleic acids such as omega-6 fatty acid (C18:2) methyl esters and 1,2-propanediol, as well as beverage stabilizers such as polyvinylpyrrolidone polymer or polyvinylimidazole-polyvinylpyrrolidone copolymer. Animal feed additives, food additives for humans and food supplements are listed in paragraph 1.

[5002] Reference RF1 defines in more detail. The conversion steps for the production of animal feed additives, food additives for humans, and dietary supplements can be carried out by one or more synthesis steps and can be performed using conventional synthesis and techniques known to a specialist. The term "aroma chemical and aroma composition" encompasses a volatile organic compound with a molecular weight between 70 and 250 g / mol containing a functional group with a carbon skeleton of 5 to 16 carbon atoms, including linear, branched, cyclic (e.g., with a ring size of C5-C18), bicyclic, or tricyclic aliphatic chains, and not necessarily one or more unsaturated structural elements such as double bonds, triple bonds, aromatics, or heteroaromatics. The one or more additional functional groups are preferably selected from alcohols, ethers, esters, ketones, aldehydes, acetals, carboxylic acids, nitriles, thiols, or amines. In one aspect, the aroma chemical is a terpene-based aroma chemical, selected, for example, from monoterpenes and monoterpenoids, sesquiterpenes and sesquiterpenoids, diterpenes, triterpenes, or tetraterpenes.Aroma chemicals can be combined with other aroma chemicals to form an aroma composition. Aroma chemicals and aroma compositions are discussed in paragraph [number].

[5003] The reference RF1 is defined in more detail. Conversion steps for the production of the aroma chemical and aroma composition can be carried out by one or more synthesis steps and can be performed using conventional synthesis and techniques known to a specialist. The term "aqueous polymer dispersion" includes aqueous compositions containing dispersed polymers and described in section

[6001] Reference RF1, entitled "aqueous polymer dispersion", defines the dispersed polymers in more detail. These polymers can be selected from acrylic emulsion polymers, styrene-acrylic emulsion polymers, styrene-butadiene dispersions, aqueous dispersions with composite particles, acrylate-alkyd hybrid dispersions, polyurethanes (including UV-curable polyurethanes), and polyurethane-poly(meth)acrylate hybrid polymers. The term "emulsion polymer" encompasses polymers produced by free-radical emulsion polymerization. Aqueous polyurethane dispersions are discussed in section [number missing in original text].

[6002] Reference RF1, entitled "Polyurethane dispersions", is defined in more detail. UV-curable polyurethanes are described in section

[6017] further defined in reference RF1. Polyurethane and poly(meth)acrylate hybrid polymers are described in section

[6016] further defined by the reference RF1. The term "polymeric dispersant" preferably includes polymers with a polyether-side chain, in particular polycarboxylate ether polymers and polycondensation products, which are described in paragraph

[6020] Reference RF1, entitled "Polymeric Dispersant," defines these in more detail. The conversion (polymerization) steps for the production of aqueous polymer dispersions with emulsion polymers are described in section [section number missing in original text].

[6003] further defined in reference RF1 entitled "Emulsion polymerization". The compositions and uses of aqueous polymer dispersions and polymeric dispersants are further defined in the following sections of Reference RF1: Section

[6004] entitled "Uses of aqueous polymer dispersions", section

[6005] entitled "Binders for architectural and construction coatings", section

[6006] entitled "Binders for paper coating", section

[6007] with the title "Binder for fiber bonding", Section

[6008] entitled "Adhesive polymers and adhesive compositions", Section

[6015] entitled "Aqueous polyurethane dispersions for coating compositions", Section

[6016] entitled "Aqueous polyurethane-poly(meth)acrylate hybrid polymers for coating compositions", Section

[6017] entitled "Aqueous UV-curable polyurethane dispersions, their manufacture and use and compositions containing them", Section

[6018] entitled “Inorganic binder compositions with polymeric dispersants and their use”, Section

[6019] entitled "100% curable coating compositions made of UV crosslinkable poly(meth)acrylate and their use in the manufacture of pressure-sensitive self-adhesive articles". Polyisocyanates, compositions containing them, and their uses are discussed in section

[6010] further defined in reference RF1 entitled "Polyisocyanates". Hyperbranched polyester polyols and their uses are discussed in section

[6011] Reference RF1, entitled "Organically solvent-based hyperbranched polyester polyols for coating compositions," is defined in more detail. The conversion steps for producing the hyperbranched polyester polyols are described in section

[6012] further defined in reference RF1 entitled "Production of organic solvent-based hyperbranched polyester polyols". Coating compositions containing hyperbranched polyester polyols, polyisocyanates and additives, as well as substrates coated therewith, are described in section

[6013] further defined in reference RF1 entitled "Organic solvent-based two-component coating compositions with hyperbranched polyester polyols and polyisocyanates". Unsaturated polyester polyols, solvent-based coating compositions containing these unsaturated polyester polyols, and substrates for coating with these coating compositions are described in section

[6018] further defines reference RF1 entitled "Organic solvent-based coating compositions with unsaturated polyester polyols". 100% curable coating compositions are described in section

[6019] further defines the reference RF1. Polymer dispersants for inorganic binder compositions are discussed in section

[6020] further defines the reference RF1. Inorganic binder compositions with polymeric dispersants and their use are discussed in section

[6021] Reference RF1 is defined in more detail. The conversion steps for the production of the polymeric dispersants are described in section

[6020] further defines the reference RF1. The term "cosmetic surfactant", as used here, includes non-ionic, anionic, cationic and amphoteric surfactants and is defined in paragraph

[7002] Reference RF1 defines the term "emollient" as used here. It refers to a chemical compound used to protect, moisturize, and / or lubricate the skin and is further defined in paragraph [reference number missing in original text].

[7003] further defined by the reference RF1. The term "wax", as used here, includes pearlescent agents and opacifying agents and is defined in paragraph

[7004] further defined by the reference RF1. The term "cosmetic polymer", as used here, encompasses any polymer that can be used as a component of a cosmetic formulation and is defined in paragraph

[7005] further defined by the reference RF1. The term "UV filter", as used here, refers to a chemical compound that blocks or absorbs ultraviolet light and is discussed in paragraph

[7006] further defined by the reference RF1. The term "other cosmetic ingredient," as used here, encompasses any ingredient suitable for the manufacture of a cosmetic formulation. Several sources state cosmetically acceptable ingredients. For example, the Cosing database on the European Commission's website contains cosmetic ingredients, and the International Cosmetic Ingredient Dictionary and Handbook, published by the Personal Care Products Council (PCPC), lists cosmetic ingredients. The term "composition and / or formulation thereof" in relation to the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter and / or other cosmetic ingredient refers to personal care and / or cosmetic compositions or formulations described in paragraph

[7007] The conversion steps for the production of the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, or other cosmetic ingredient are defined in more detail in paragraph [number].

[7008] further defined by the reference RF1. The terms "polymer B", "polymer composition B", "coating composition", "further functional composition", "film", "shaped body", "coating" and "coated substrate" are known to those skilled in the art and are used in the paragraphs

[8000] until

[8005] further defines the reference RF1. In a preferred embodiment, the target product is selected from: i) a building block or monomer; or ii) a polymer, preferably polymer A, a polymer composition, preferably polymer composition A, or a polymer product, preferably polymer product A; or iii) a cleaning polymer, cleaning surfactant, descaling agent, cleaning biocide, or a composition or formulation thereof; or iv) an agrochemical composition, agrochemical formulation aid, or agrochemical active substance; or v) an active pharmaceutical ingredient or an intermediate thereof, a pharmaceutical excipient, a feed additive, a human food additive, a dietary supplement, a flavoring chemical, or a flavoring composition;or vi) Aqueous polymer dispersion, preferably polyurethane or polyurethane-poly(meth)acrylate hybrid polymer dispersion, emulsion, binder for paper and fiber coatings, UV-curable acrylic polymer for hot melts and coatings, polyisocyanates, hyperbranched polyester polyols, polymeric dispersant for inorganic binder compositions, unsaturated polyester polyol or 100% curable composition; or vii) Cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, other cosmetic ingredients or compositions or formulations thereof; or viii) Polymer B, polymer composition B, coating composition, other functional composition, film, molded body, coating or coated substrate.; In a preferred embodiment, the content of N-methyl-2-pyrrolidone (NMP) in the target product is 1% by weight or more, preferably 2% by weight or more, more preferably 5% by weight or more, more preferably 15% by weight or more, more preferably 30% by weight or more, more preferably 40% by weight or more, more preferably 60% by weight or more, more preferably 80% by weight. or more, more preferably 90% by weight or more, more preferably 95% by weight or more; and / or wherein the content of N-methyl-2-pyrrolidone (NMP) in the target product is 100% by weight or less, preferably 95% by weight or less, more preferably 90% by weight or less, more preferably 50% by weight or less, more preferably 25% by weight or less, more preferably 10% by weight or less; and wherein the content is preferably determined on the basis of identity preservation and / or separation and / or mass balance and / or the book and chain of claims of the custody models, preferably on the basis of mass balance, preferably the International Sustainability and Carbon Certification (ISCC) Standard. In a preferred embodiment, the method, preferably according to one of the embodiments mentioned above, comprises the step: Conversion of the product of the process, namely N-methyl-2-pyrrolidone (NMP), which can be obtained or is obtained by one of the above embodiments, to obtain the target product. The present invention further comprises a target product, preferably a target product according to one of the embodiments mentioned herein, which is produced or can be produced by a process that includes the use of a steam stream produced by the process described herein. The present invention is further characterized by the following embodiments, including the individual and specific combinations of embodiments indicated by the respective dependencies. It should be noted in particular that in each case where a specific number of embodiments is defined, for example in the context of a term such as "method according to one of embodiments 1 to 4", each embodiment in this set is explicitly disclosed to the person skilled in the art, which means that the formulation of this term is to be understood by the person skilled in the art as synonymous with "method according to one of embodiments 1, 2, 3 and 4".Furthermore, it is expressly pointed out that the following list of exemplary embodiments constitutes an adequate, structured part of the general description, which is directed towards preferred aspects of the present invention and thus appropriately supports, but does not constitute, the claims of the present invention. 1. Process for the purification of N-methyl-2-pyrrolidone (NMP), the process comprising (i) introducing a feedstock stream comprising NMP, preferably the dehydrated product stream obtained in (b), into a column, and heating the feedstock stream to separate it into an NMP-containing stream, a gaseous overhead stream, and a bottom stream, (ii) Compressing the gaseous overhead stream obtained in (i), obtaining a compressed gaseous overhead stream, (iii) Transferring heat from the compressed gaseous overhead stream to a process stream of a chemical process, preferably to a process stream of this process or of another chemical process, more preferably to the product stream obtained in (a), to the bottom stream obtained in (i), or to the product stream obtained in (a) and to the bottom stream obtained in (i), obtaining a cooled and at least partially condensed overhead stream, (iv) Relaxing the cooled and at least partially condensed head stream, obtaining a relaxed head stream, (v) Returning at least part of the relaxed overhead flow to the column according to (i). 2. The method according to embodiment 1, wherein the raw material stream introduced into the column in (i) comprises 95.0 to 99.9 wt%, preferably 97.6 to 99.7 wt%, more preferably 98.6 to 99.6 wt% of NMP. 3. The method according to embodiment 1 or 2, wherein the raw material stream introduced into the column in (i) comprises 0.01 to 0.10 wt%, preferably 0.03 to 0.08 wt%, more preferably 0.04 to 0.07 wt%, of H2O. 4. The process according to one of embodiments 1 to 3, wherein the raw material stream introduced into the column in (i) comprises 0.1 to 1.7 wt%, preferably 0.3 to 1.4 wt%, more preferably 0.5 to 1.2 wt%, of high-boiling compounds, wherein the high-boiling compounds preferably comprise one or more of gamma-butyrolactone, oligomers of gamma-butyrolactone, and hydroxybutyric acid. 5. The method according to one of embodiments 1 to 4, wherein the raw material stream in (i) is introduced into the column at a mass flow rate in the range of 100 to 10,000 kg / h, preferably from 3,500 to 5,500 kg / h, more preferably from 4,000 to 4,750 kg / h. 6. The method according to one of embodiments 1 to 5, wherein the temperature in the column according to (i) is in a range of 100 to 140 °C, preferably 105 to 135 °C, more preferably 110 to 130 °C, more preferably 112 to 128 °C. 7. The method according to one of embodiments 1 to 6, wherein the pressure in the column according to (i) is in a range of 40 to 110 mbara, preferably 50 to 100 mbara, more preferably 55 to 90 mbara, more preferably 60 to 84 mbara. 8. The method according to one of embodiments 1 to 7, wherein the column according to (i) is a distillation column, wherein the column preferably comprises one or more, more preferably three, packing elements, wherein the one or more packing elements are more preferably independent of one another and have a low pressure loss, wherein the one or more packing elements more preferably comprise one or more liquid collectors and liquid distributors, and wherein the one or more packing elements are more preferably independent of one another and are sheet metal packings or wire mesh packings. 9. The method according to one of embodiments 1 to 8, wherein the gaseous overhead stream obtained in (i) comprises 95.0 to 99.8 wt%, preferably 97.8 to 99.6 wt%, more preferably 98.6 to 99.4 wt% of NMP. 10. The method according to one of embodiments 1 to 9, wherein the gaseous overhead stream obtained in (i) comprises 0.1 to 1.5 wt%, preferably 0.3 to 1.3 wt%, more preferably 0.5 to 1.2 wt%, of H2O. 11. The method according to one of the embodiments I to 10, wherein the ratio of the mass flow rate of the gaseous overhead stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column is in the range of 0.95:1 to 1.20:1, preferably from 1.00:1 to 1.15:1, more preferably from 1.05:1 to 1.09:1. 12. The method according to one of embodiments 1 to 11, wherein the NMP-containing stream obtained in (i) comprises 99.75 to 99.9999 wt%, preferably 99.80 to 99.999 wt%, more preferably 99.85 to 99.99 wt% of NMP. 13. The method according to one of embodiments 1 to 12, wherein the NMP-containing stream obtained in (i) comprises H2O of greater than 0 to 150 ppm, preferably of 10 to 110 ppm, more preferably of 15 to 100 ppm. 14. The method according to one of embodiments 1 to 13, wherein the NMP-containing stream obtained in (i) is obtained in a side draw of the column according to (i). 15. The method according to one of embodiments 1 to 14, wherein the ratio of the mass flow rate of the NMP-containing stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column is in the range of 0.75:1 to 1.10:1, preferably from 0.85:1 to 1.00:1, more preferably from 0.90:1 to 0.94:1. 16. The method according to one of embodiments 1 to 15, wherein the ratio of the mass flow rate of the bottom stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column is in the range of 0.001 :1 to 0.06:1, preferably from 0.01 :1 to 0.05:1, more preferably from 0.02:1 to 0.04:1. 17. The method according to one of embodiments 1 to 16, wherein the sump stream obtained in (i) comprises 60 to 72 wt%, preferably 62 to 70 wt%, more preferably 64 to 68 wt% of NMP. 18. The method according to one of embodiments 1 to 17, wherein the bottom stream obtained in (i) comprises 15 to 55 wt%, preferably 25 to 45 wt%, more preferably 29 to 39 wt% of high-boiling compounds, wherein the high-boiling compounds preferably comprise 1,4-butanediol. 19. The method according to one of embodiments 1 to 18, wherein the heating according to (i) is carried out by means of one or more, preferably two, evaporators, wherein the one or more evaporators are preferably selected independently of each other from the group consisting of natural circulation evaporators and falling film evaporators. 20. The method according to one of embodiments 1 to 19, wherein the temperature difference from the gaseous top stream obtained in (i) to the bottom stream obtained in (i) is in the range of 10 to 20 °C, preferably from 12 to 18 °C, more preferably from 13 to 16 °C. 21. The method according to one of embodiments 1 to 20, wherein the gaseous headstream obtained in (i) is compressed in (ii) to a pressure in the range of 150 to 450 mbara, preferably 170 to 350 mbara, more preferably 180 to 290 mbara, more preferably 190 to 260 mbara. 22. The method according to one of embodiments 1 to 21, wherein the compression according to (ii) is carried out by means of a compressor or a blower, preferably a multi-stage blower. 23. The method according to one of embodiments 1 to 22, wherein the compressed gaseous headstream obtained in (ii) has a temperature in the range of 90 to 190 °C, preferably 100 to 180 °C, more preferably 111 to 172 °C, more preferably 147 to 172 °C. 24. The method according to one of embodiments 1 to 23, wherein the sump flow obtained according to (i) is split into a returnable sump flow and an excess sump flow. 25. The method according to embodiment 24, wherein according to (iii) heat is transferred from the compressed overhead stream to the recirculated bottom stream, obtaining a heated recirculated bottom stream, and wherein the heated recirculated bottom stream is recirculated into the column according to (i). 26. The method according to one of embodiments 1 to 25, wherein the transfer of heat according to (iii) is carried out by means of an evaporator, wherein the evaporator is preferably selected from the group consisting of natural circulation evaporators and falling film evaporators. 27. The method according to one of embodiments 1 to 26, wherein the cooled and at least partially condensed overhead stream obtained in (iii) has a temperature in the range of 130 to 156 °C, preferably 135 to 151 °C, more preferably 140 to 146 °C. 28. The method according to one of embodiments 1 to 27, wherein the cooled and at least partially condensed overhead stream obtained in (iii) has a pressure in the range of 150 to 450 mbara, preferably 170 to 350 mbara, more preferably 180 to 290 mbara, more preferably 190 to 260 mbara. 29. The method according to one of embodiments 1 to 28, wherein the chemical method comprises the production of NMP. 30. The method according to one of embodiments 1 to 29, wherein the process stream in (iii) comprises NMP. 31. The method according to one of embodiments 1 to 30, wherein the process stream comprises (iii) H2O. 32. The method according to one of the embodiments I to 31, wherein the relaxation according to (iv) is carried out by means of a relaxation valve. 33. The method according to one of embodiments 1 to 32, wherein in (iv) the cooled and at least partially condensed overhead stream is expanded to a pressure in the range of 30 to 90 mbara, preferably 40 to 80 mbara, more preferably 50 to 70 mbara, more preferably 55 to 65 mbara. 34. The method according to one of embodiments 1 to 33, wherein the relaxed overhead flow obtained in (iv) has a temperature in the range of 88 to 104 °C, preferably 83 to 99 °C, more preferably 88 to 94 °C. 35. The method according to one of embodiments 1 to 34, wherein a portion of the relaxed overhead stream obtained in (iv) is liquid and a portion of the relaxed overhead stream obtained in (iv) is gaseous, wherein preferably 81 to 99 wt.%, more preferably 85 to 95 wt.%, more preferably 88 to 92 wt.% of the relaxed overhead stream obtained in (iv) is liquid, and wherein preferably 1 to 19 wt.%, more preferably 5 to 15 wt.%, more preferably 8 to 12 wt.% of the relaxed overhead stream obtained in (iv) is gaseous. 36. The method according to one of embodiments 1 to 35, further comprising (iv) and (v) (iv.1 ) Cooling of the relaxed head stream obtained in (iv). 37. The method according to embodiment 36, wherein the cooling according to (iv.1 ) is carried out by means of a condenser. 38. The method according to embodiment 36 or 37, wherein in (iv.1 ) the relaxed overhead flow is cooled to a temperature in the range of 88 to 104 °C, preferably from 83 to 99 °C, more preferably from 88 to 94 °C. 39. The method according to one of the embodiments 36 to 38, wherein the relaxed head flow obtained in (iv.1 ) has a pressure in the range of 30 to 90 mbara, preferably 40 to 80 mbara, more preferably 50 to 70 mbara, more preferably 55 to 65 mbara. 40. The method according to one of embodiments 36 to 39, wherein a portion of the relaxed overhead stream obtained in (iv.1) is liquid and a portion of the relaxed overhead stream obtained in (iv.1) is gaseous. 41. The method according to embodiment 40, wherein in (v) the liquid part of the relaxed overhead stream obtained in (iv) is recycled into the column according to (i). 42. The method according to one of embodiments 1 to 41, wherein the relaxed overhead flow obtained in (iv) or (iv.1) has a mass flow rate in the range of 100 to 10,000 kg / h, preferably 4,000 to 5,500 kg / h, more preferably 4,500 to 5,000 kg / h. 43. The method according to one of embodiments 1 to 42, wherein 50 to 100 wt%, preferably 80 to 98 wt%, more preferably 88 to 96 wt%, of the relaxed overhead stream obtained in (iv) or (iv.1) is recycled to the column according to (i). 44. The method according to one of embodiments 1 to 43, wherein the ratio of the mass flow rate of the portion of the expanded overhead stream recycled to the column according to (v) to the mass flow rate of the raw material stream introduced into the column is in the range of 0.94:1 to 1.10:1, preferably from 0.98:1 to 1.06:1, more preferably from 1.01:1 to 1.03:1. 45. The method according to one of embodiments 1 to 44, wherein the portion of the expanded overhead stream recirculated into the column according to (v) has a temperature in a range from 78 to 125 °C, preferably from 83 to 120 °C, more preferably from 88 to 115 °C. 46. ​​The method according to one of embodiments 1 to 45, wherein the portion of the expanded overhead stream returned to the column according to (v) has a pressure in the range of 40 to 90 mbara, preferably 50 to 80 mbara, more preferably 55 to 75 mbara, more preferably 55 to 65 mbara. 47. The method according to one of embodiments 1 to 46, wherein the portion of the expanded overhead stream returned to the column according to (v) is liquid. 48. The method according to one of embodiments 1 to 47, further comprising (i) (a) Reacting a reactant stream comprising gamma-butyrolactone (GBL) and monomethylamine (MMA) under reaction conditions to obtain a product stream comprising NMP and H2O, and (b) Introducing the product stream obtained in (a) into a column, and heating the product stream to separate it into a dehydrated product stream and an l-hO-containing stream, wherein the process is for the production and purification of N-methyl-2-pyrrolidone (NMP). 49. The method according to embodiment 48, wherein the reactant stream has a molar ratio, GBL:MMA, of gamma-butyrolactone to monomethylamine in the range of 0.9:1 to 1.1:1, preferably from 0.99:1 to 1.01:1. 50. The method according to embodiment 48 or 49, wherein the conversion according to (a) takes place in a tubular reactor. 51. The method according to one of embodiments 48 to 50, wherein the reaction conditions according to (a) comprise heating the reactant stream to a temperature in the range of 320 to 400 °C, preferably from 340 to 380 °C, more preferably from 350 to 370 °C. 52. The method according to one of embodiments 48 to 51, wherein the reaction conditions according to (a) comprise applying a pressure in the range of 70 to 110 bara, preferably 80 to 100 bara, more preferably 85 to 95 bara. 53. The method according to one of embodiments 48 to 52, wherein the reaction conditions include an adiabatic conversion in (a). 54. The method according to one of embodiments 48 to 53, wherein the product stream introduced into the column according to (b) has a temperature in the range of 125 to 195 °C, preferably 145 to 175 °C, more preferably 155 to 165 °C. 55. The method according to one of embodiments 48 to 54, wherein the product stream introduced into the column according to (b) has a pressure in the range of 800 to 1,000 mbara, preferably from 825 to 975 mbara, more preferably from 900 to 950 mbara. 56. The method according to one of embodiments 48 to 55, wherein the heating according to (b) is carried out by means of an evaporator, wherein the evaporator is preferably selected from the group consisting of natural circulation evaporators and falling film evaporators. 57. The method according to one of embodiments 48 to 56, wherein the temperature in the column according to (b) is in a range of 95 to 240 °C, preferably from 100 to 235 °C, more preferably from 105 to 230 °C. 58. The method according to one of the embodiments 48 to 57, wherein the pressure in the column according to (b) is in a range of 600 to 800 mbara, preferably from 625 to 775 mbara, more preferably from 650 to 750 mbara. 59. Method for producing a target product by converting N-methyl-2-pyrrolidone (NMP) that can be obtained or has been obtained according to the method of any one of claims 1 to 58. 60. The method according to embodiment 59, wherein the N-methyl-2-pyrrolidone (NMP) content in the target product is 1% by weight or more, preferably 2% by weight or more, more preferably 5% by weight or more, more preferably 15% by weight or more, more preferably 30% by weight or more, more preferably 40% by weight or more, more preferably 60% by weight or more, more preferably 80% by weight or more, more preferably 90% by weight or more, more preferably 95% by weight or more; and / or wherein the N-methyl-2-pyrrolidone (NMP) content in the target product is 100% by weight or less, preferably 95% by weight or less, more preferably 90% by weight or less, more preferably 50% by weight or less, more preferably 25% by weight or less, more preferably 10% by weight or less;and wherein the content is preferably determined on the basis of identity preservation and / or segregation and / or mass balance and / or book and claim chain of custody models, preferably on the basis of mass balance, preferably the International Sustainability and Carbon Certification (ISCC) Standard.; 61. The method according to embodiment 59 or 60, wherein the method, preferably according to one of the embodiments mentioned above, comprises the step: Conversion of the product of the process, namely N-methyl-2-pyrrolidone (NMP), which can be obtained or is obtained by one of the above embodiments, to obtain the target product. The present invention is further illustrated by the following reference examples, examples and comparative examples. EXAMPLES Reference example 1: Production of NMP NMP is produced in a reactor. The reactant stream introduced into the reactor consists of gamma-butyrolactone and monomethylamine in a 1:1 molar ratio. The reaction conditions include a temperature of 360 °C and a pressure of 90 bar. The product stream containing NMP and H₂O is processed in a distillation column to remove some of the H₂O, yielding an NMP-containing stream. Example 2: Purification of NMP according to the present invention The NMP-containing electricity obtained from the production of NMP according to reference example 1 is further processed. The purification of NMP is carried out using a system comprising a distillation column, a compressor, two evaporators, a pressure relief valve, and a condenser, as shown in Figure 1. The stream fed into the distillation column has an NMP content of 98.85 wt%, a H₂O content of 0.05 wt%, and a high-boiling content of 1.1 wt%. The stream is fed into the distillation column at a mass flow rate of 4550 kg / h. The bottom temperature of the distillation column is approximately 128 °C at a pressure of approximately 84 mbar, while the top temperature is approximately 112 °C at a pressure of approximately 60 mbar. The lower part of the distillation column is flanked by two evaporators used for heating. One evaporator (see evaporator 3a in Fig. 1) is operated with the top stream via compressor 2. In evaporator 3a, the vapors condense and heat the distillation column. The other evaporator is used to start up the distillation column and to compensate for control fluctuations; this evaporator can be operated with steam (see evaporator 3b in Fig. 1). The vapor is collected at the top of the distillation column and has a content of 98.9 wt% NMP and 1.1 wt% H₂O. The mass flow rate of the top stream is 4850 kg / h. The vapor is fed from the top of the distillation column into the evaporator 3a via compressor 2. Compressor 2 has an electrical drive power P ei of 55 kW. The headstream flow is compressed in the compressor to a pressure of 250 mbar. The resulting- Liquid condensate from evaporator 3a is fed into the overhead condenser 5 via expansion valve 4. Evaporator 3a provides a thermal output of 590 kW, while the steam-operated evaporator 3b operates at a thermal output of 162 kW. The coefficient of performance (COP) for this process arrangement is: COP = Qtherm / Pei = 590 / 55 = 10.7. Assuming an annual operating time of 8000 h and a steam saving of 90% of the normal steam requirement, this can result in a saving of approximately 8,100 t / a or approximately 875 t / a CO2. Comparative example 3: Purification of NMP The NMP-containing stream obtained from the production of NMP according to Reference Example 1 is further processed. In the pure distillation of NMP, the raw material is continuously fed into the middle section of a distillation column. The column has three low-pressure-loss packing elements (sheet metal or wire mesh packings), each with a liquid collector (below) and a liquid distributor (above). The NMP raw material is fed into the liquid distributor of the bottom packing at a temperature of 120 °C. The column sump is heated with 16 bar steam via an evaporator (natural circulation evaporator or falling film evaporator). The sump temperature is approximately 128 °C. At the top of the column, the vapors are condensed using an air cooler or water cooler. Some of the liquid product collected at the top is drawn off, and the majority is returned to the top liquid distributor as reflux. The reflux ratio (recirculation / drawoff) is 20–25:1. All liquid is drawn off from the liquid collector below the top packing and fed into the product container. A portion of this container is returned to the column, while the majority, as pure NMP, is drawn off via a cooler to the tank farm. The reflux ratio (return / drawoff) is 1:3-4. At full capacity, an NMP output of 4,200 kg / h with a water content of <50 ppm can be obtained. This distillation process results in a steam requirement of 1.3 t at full capacity. 16 bar steam (Qtherm= 750 kW thermal power) or a specific energy consumption of 180 kW per t (NMP). Description of the image Figure 1: shows a schematic representation of a plant for the purification of NMP according to the present invention, in particular comprising a distillation column, two evaporators, a compressor, an expansion valve, and a condenser. List of reference symbols 1 distillation column 2 compressors 3a, 3b Evaporator 4. Relief valve 5 Capacitor Cited literature - WO 2021 / 093918 A1 - US 2013 / 0267751 A1 - EP 4091688 A1

Claims

Claims 1. A process for the purification of N-methyl-2-pyrrolidone (NMP), comprising the process (i) Introducing a feedstock stream comprising NMP into a column, and heating the feedstock stream to separate it into an NMP-containing stream, a gaseous overhead stream, and a bottom stream, (ii) Compressing the gaseous overhead stream obtained in (i), obtaining a compressed gaseous overhead stream, (iii) Transferring heat from the compressed gaseous overhead stream to a process stream of a chemical process, obtaining a cooled and at least partially condensed overhead stream, (iv) Relaxing the cooled and at least partially condensed head stream, obtaining a relaxed head stream, (v) Returning at least part of the relaxed overhead flow to the column according to (i).

2. The method according to claim 1, wherein the raw material stream introduced into the column in (i) comprises 95.0 to 99.9 wt.%, preferably 97.6 to 99.7 wt.%, more preferably 98.6 to 99.6 wt.% of NMP.

3. The method according to one of claims 1 to 2, wherein the temperature in the column according to (i) is in a range of 100 to 140 °C, preferably 105 to 135 °C, more preferably 110 to 130 °C, more preferably 112 to 128 °C.

4. The method according to any one of claims 1 to 3, wherein the ratio of the mass flow rate of the gaseous overhead stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column is in the range of 0.95:1 to 1.20:1, preferably from 1.00:1 to 1.15:1, more preferably from 1.05:1 to 1.09:

1.

5. The method according to any one of claims 1 to 4, wherein the ratio of the mass flow rate of the NMP-containing stream obtained in (i) to the mass flow rate of the raw material stream introduced into the column is in the range of 0.75:1 to 1.10:1, preferably from 0.85:1 to 1.00:1, further preferred from 0.90:1 to 0.94:

1.

6. The method according to any one of claims 1 to 5, wherein the gaseous headstream obtained in (i) is compressed in (ii) to a pressure in the range of 150 to 450 mbara, preferably 170 to 350 mbara, more preferably 180 to 290 mbara, more preferably 190 to 260 mbara.

7. The method according to any one of claims 1 to 6, wherein the cooled and at least partially condensed overhead stream obtained in (iii) has a temperature in the range of 130 to 156 °C, preferably 135 to 151 °C, more preferably 140 to 146 °C.

8. The method according to any one of claims 1 to 7, wherein the chemical method comprises the production of NMP.

9. The method according to any one of claims 1 to 8, wherein the process stream in (iii) comprises NMP.

10. The method according to any one of claims 1 to 9, wherein in (iv) the cooled and at least partially condensed overhead stream is expanded to a pressure in the range of 30 to 90 mbara, preferably 40 to 80 mbara, more preferably 50 to 70 mbara, more preferably 55 to 65 mbara.

11. The method according to any one of claims 1 to 10, wherein a portion of the relaxed overhead stream obtained in (iv) is liquid and a portion of the relaxed overhead stream obtained in (iv) is gaseous, wherein preferably 81 to 99 wt.%, more preferably 85 to 95 wt.%, more preferably 88 to 92 wt.% of the relaxed overhead stream obtained in (iv) is liquid, and wherein preferably 1 to 19 wt.%, more preferably 5 to 15 wt.%, more preferably 8 to 12 wt.% of the relaxed overhead stream obtained in (iv) is gaseous.

12. The method according to any one of claims 1 to 11, further comprising (iv) and (v) (iv.1 ) Cooling of the relaxed head stream obtained in (iv).

13. The method according to claim 12, wherein in (iv.1 ) the relaxed overhead flow is cooled to a temperature in the range of 88 to 104 °C, preferably from 83 to 99 °C, more preferably from 88 to 94 °C.

14. The method according to any one of claims 1 to 13, further comprising (i) (a) Reacting a reactant stream comprising gamma-butyrolactone (GBL) and monomethylamine (MMA) under reaction conditions to obtain a product stream comprising NMP and H2O, and (b) Introducing the product stream obtained in (a) into a column, and heating the product stream to separate it into a dehydrated product stream and an H2O-containing stream, wherein the process is for the production and purification of N-methyl-2-pyrrolidone (NMP).

15. Method for producing a target product by converting N-methyl-2-pyrrolidone (NMP) that can be obtained or has been obtained according to any one of claims 1 to 14.

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