Sustainable preparation of hexamethylene diisocyanate for the production of polyurethane

Abstract

The present invention relates to a method of preparing hexamethylene diisocyanate according to claim 1, and of preparing polyurethane from hexamethylene diisocyanate, wherein methanol is used in the method in question as a raw material for the build-up of the hexamethylene moiety of the hexamethylene diisocyanate.

Description

[0001] Sustainable production of hexamethylene diisocyanate for the production of polyurethane

[0002] The present invention relates to a production process of hexamethylene diisocyanate for the synthesis of polyurethane, as well as a process for producing polyurethane from the hexamethylene diisocyanate obtained according to the above-mentioned production process and a multicomponent system for producing hexamethylene diisocyanate according to the above-mentioned production process.

[0003] To date, the industrial production of hexamethylene diisocyanate (also known as HDI, hexane-1,6-diyl diisocyanate, or 1,6-diisocyanatohexane) has been predominantly based on the use of fossil raw materials, such as synthesis gas from natural gas and petroleum-based aromatic compounds. The consistent use of renewable raw materials and / or valuable waste materials for the production of materials such as hexamethylene diisocyanate is a goal for the provision of sustainable plastics, such as polyurethane and materials derived from it.

[0004] Furthermore, the use of energy from renewable energy sources for the industrial production of chemical raw materials, such as hexamethylene diisocyanate, is being sought.

[0005] It was therefore an object of the present invention to provide a more sustainable production process for hexamethylene diisocyanate on an industrial scale, which enables the use of renewable raw materials. Furthermore, a further object of the invention was to provide a method for producing hexamethylene diisocyanate that can be used to achieve low-emission hexamethylene diisocyanate for the production of polyurethanes despite possible fluctuations in the availability of renewable energy. The term "renewable energy" is understood by those skilled in the art to mean energy from a non-depletable energy source, such as wind power, hydropower, bioenergy (e.g., electricity generation from biogas or biomass), or solar energy.

[0006] The expert understands the "sustainability" of a process, in application of the UN definition of sustainability ("sustainable development") according to the Brundtland Report of the "World Commission on Environment and Development", to mean that the implementation of the process in the present makes as little or no contribution as possible to ensuring that future generations of humanity will no longer be able to satisfy their own needs, in particular needs with regard to the use of resources such as fossil raw materials and in particular with regard to the conservation of habitats, such as the protection of the Earth's atmosphere. The invention therefore has the object of facilitating the production of hexamethylene diisocyanate,and polyurethane produced therefrom more sustainable than the production methods known from the prior art. The contribution of the production of hexamethylene diisocyanate and polyurethane to a declining satisfaction of the needs of future generations should be reduced or even eliminated. A first object of the invention is therefore a process for the production of hexamethylene diisocyanate for the production of polyurethane, comprising at least the steps: a) Providing hexamethylenediamine, which is a process product of a process comprising at least the following steps: i) Providing methanol, which is a process product of a process with at least the following steps: i-1) Providing carbon monoxide as a process product of at least a partial reduction of CO2 to CO and / or as a process product of at least a partial oxidation of organic material to CO,wherein at least one organic material is selected from at least one organic, solid compound, methane from a biological source or mixtures thereof; i-2) conversion of the provided carbon monoxide to methanol; ii) synthesis of propene from previously provided methanol by at least the following steps: ii-1) conversion of the previously provided methanol to a product mixture containing dimethyl ether, water and methanol; ii-2) conversion of starting material containing dimethyl ether, water and,

[0007] Methanol in each case from the aforementioned product mixture, at a temperature of more than 200°C by contact with a catalyst, preferably with at least one zeolite compound as catalyst, to give propene; iii) synthesis of acrylonitrile from the propene by at least the following steps: iii-1) provision of ammonia, which is a process product of a process having at least the following steps: iii- 1-1) provision of hydrogen gas as a product of an electrolysis of water, preferably using electrical energy generated from renewable energy; iii- 1-2) reaction of the provided hydrogen gas with gaseous nitrogen to give ammonia; iii-2) reaction of the propene with the provided ammonia to give acrylonitrile;iv) Synthesis of adiponitrile from acrylonitrile by at least the following steps: introducing a mixture containing water, said acrylonitrile, and at least one electrolyte salt into the cathode compartment of an electrolytic cell and contacting the mixture with a cathode to which an electric current is applied; cathodic hydrodimerization of the acrylonitrile to form an adiponitrile-containing product mixture;

[0008] Extraction of the adiponitrile-containing product mixture from the cathode compartment of the electrolysis cell and optional purification of the adiponitrile; v) synthesis of hexamethylenediamine from the adiponitrile by at least the following steps:

[0009] Providing hydrogen gas as a product of electrolysis, preferably using electrical energy generated from renewable energy;

[0010] Hydrogenation of the adiponitrile with the hydrogen gas to form hexamethylenediamine; b) Production of phosgene by at least the following process steps: i) Provision of carbon monoxide as a process product of at least one partial reduction of CO2 to CO and / or as a process product of at least one partial oxidation of organic material to CO, wherein at least one organic material is selected from at least one organic, solid compound, an organic, liquid monohydroxyalkyl compound, methane from a biological source or mixtures thereof; ii) Reaction of the carbon monoxide from step i) with chlorine to form phosgene; c) Reaction of the provided hexamethylenediamine with the phosgene to form hexamethylene diisocyanate.

[0011] According to the invention, a "catalyzed reaction" or "catalytic conversion" takes place using a catalyst that catalyzes the product formation from at least one reactant (e.g., carbon dioxide or methanol) by reducing the energy required and / or by increasing selectivity while increasing the product yield, compared to the same reaction under the same reaction conditions but in the absence of the catalyst. For example, the conversion according to step a) ii-2) is a catalytic conversion of said starting material to propene.

[0012] According to the present invention, a material or chemical compound is organic if the material / chemical compound contains at least one covalent carbon-hydrogen bond. A substance or material is defined as solid if it exists as a solid at 25°C and 1013 mbar. A substance or material is defined as liquid if it exists as a liquid at 25°C and 1013 mbar.

[0013] In step a) of the process according to the invention, hexamethylenediamine (also referred to as 1,6-diaminohexane or hexane-1,6-diamine) is provided. For the provision of the hexamethylenediamine, it is sufficient according to the invention if the hexamethylenediamine provided is an actual process product of at least the steps i), ii), iii), iv) and v) mentioned under a). This means that for carrying out the step of providing the hexamethylenediamine, it is sufficient to remove the hexamethylenediamine produced in this way as raw material from a storage container or from a feed line merely as part of a delivery in order to feed it at least to step c) of the process according to the invention.In this case, the hexamethylenediamine producer, as the executor of the process according to the invention, does not carry out the steps i) and ii) mentioned under a) of the process according to the invention for the preparation of the hexamethylenediamine himself, but only ensures that the hexamethylenediamine provided has been prepared by applying at least the steps i) and ii) mentioned under a) and is thus the actual product of the process.

[0014] It is also possible according to the invention if, in order to provide the hexamethylenediamine, the steps i) to v) mentioned at least under a) for producing the hexamethylenediamine are carried out as integral steps of a process according to the invention for producing hexamethylene diisocyanate by the hexamethylene diisocyanate producer and the hexamethylenediamine obtained in this way, optionally after intermediate storage in a storage container, is fed at least to step c) of the process according to the invention.

[0015] The possibilities of provision, i.e. delivery or in-house production of the specific hexamethylenediamine by the hexamethylene diisocyanate producer also apply to the following embodiments of steps i) to v) mentioned under a).

[0016] The step i) mentioned under a) in the process according to the invention requires the provision of methanol, which is an actual process product of a process with at least the following steps: i-1) Conversion of CO to methanol, wherein the CO is a process product of at least one partial reduction of CO2 to CO and / or a process product of at least one partial oxidation of organic material to CO, wherein at least one organic material is selected from at least one organic, solid compound, methane from a biological source or mixtures thereof.

[0017] According to the present invention, for the provision of methanol, it is sufficient if the methanol is an actual process product of at least the reaction mentioned under i-1), whereby carbon monoxide (also referred to as CO) is used for this reaction, which in turn is an actual process product of a specific process. This means that for the implementation of the methanol provision step, it is sufficient to simply withdraw the methanol produced in this manner as a raw material from a storage container or a supply line.In this case, the hexamethylene diisocyanate producer as the executor of the process according to the invention or the supplier of the hexamethylenediamine provided for the process according to the invention does not carry out the aforementioned reaction for producing the methanol itself, but only ensures that the methanol provided for the provision of the hexamethylenediamine has been produced by applying at least the said step i-1) and is thus the actual product of the process.

[0018] It is also possible according to the invention if, in order to provide the methanol, at least the aforementioned reaction for producing the methanol is carried out as an integral step of the process according to the invention for producing hexamethylene diisocyanate by the hexamethylene diisocyanate producer or the supplier of the hexamethylenediamine provided, and the methanol obtained thereby, optionally after intermediate storage in a storage container, is fed to the synthesis of hexamethylenediamine provided under step a) of the process by carrying out at least steps ii-1), ii-2), iii), iv) and v).

[0019] The options for providing, i.e. supplying or producing the special methanol by the hexamethylene diisocyanate producer, also apply to the following embodiments of providing the methanol.

[0020] To produce methanol, carbon oxides are typically reacted with hydrogen (the mixture is also known as synthesis gas). This process is exothermic and can be described by the following reaction equations:

[0021] CO + 2H2^ CH3OH

[0022] CO2 + 3H2CH2OH + H2O

[0023] Both reactions are coupled by the also exothermic water-gas shift reaction, which can be described as follows:

[0024] CO + H2O CO2 + H2 Conventionally, synthesis gas consisting primarily of CO and H2 is used for methanol synthesis, which in turn is produced from natural gas (fossil methane) and steam in a reforming process (steam reforming). The composition of the synthesis gas has a strong influence on its optimal use. The composition can be described by the stoichiometry number (SZ):

[0025] For SZ = 2, the reactants are present in the stoichiometric ratio according to the above-mentioned reaction equations. However, slightly higher values ​​for SZ (2.01-2.1) are actually used, which is achieved by a higher hydrogen content in the synthesis gas (Dittmeyer et al., "Chemische Technik," Volume 4, 5th edition).

[0026] In the process according to the invention, the carbon monoxide required for the conversion to methanol production is not provided by conventional steam reforming using fossil carbon sources (natural gas), but by partial reduction of carbon dioxide and / or by partial oxidation (and if necessary gasification) of said organic material to CO.

[0027] In the partial oxidation of organic, solid material (preferably organic, polymeric material), according to the process according to the invention, CO is provided from organic, solid material (preferably from used polymer waste fractions) and oxygen-containing gas by converting said organic, solid material under partial oxidation into a gas containing CO (hereinafter also referred to as gasification).

[0028] By using polymer-containing waste fractions, which can, for example, consist predominantly of PET, PE, PP, polyurethane or polycarbonate-containing waste fractions (hereinafter referred to as polymer waste fraction), to provide CO, these polymer-containing waste fractions are recycled and thus hexamethylene diisocyanate and also polyurethane from this hexamethylene diisocyanate are produced with improved sustainability.

[0029] A "polymeric compound" is a molecule with a relative molar mass (Mw) of at least 2000 g / mol, whose chemical structure predominantly comprises multiply repeating structural units derived from one or more different molecules of lower relative molar mass. Unless explicitly stated otherwise, the average molar masses stated for polymers or polymeric compounds in this application are always weight-average molar masses Mw, which can generally be determined by gel permeation chromatography using an RI detector, with the measurement conveniently being carried out against an external standard. A "polymeric material" is a material containing at least one polymeric compound.Through partial oxidation, organic material (preferably solid organic material, particularly preferably polymeric organic material, most preferably the polymer waste fraction) and oxygen undergo a partial oxidation reaction, resulting in a product gas mixture containing hydrogen and CO and, if appropriate, by-products. By-products include, in particular, hydrocarbons with 1 to 8 carbon atoms. The product gas mixture also includes, among other substances, CO2 and water vapor.

[0030] As a further by-product, a residual fraction that cannot be further processed is obtained from the gasification process.

[0031] The temperature required for gasification is achieved at least partially by partial combustion (partial oxidation) of the organic solid material (preferably the polymeric organic material, particularly preferably the polymer waste fraction) with an oxygen-containing gas. The partial oxidation of the introduced organic solid material is carried out in the reactor at a temperature of at least 400°C. Preferably, the partial oxidation of the material in the reactor is carried out at a temperature in a temperature range from 600°C to 1500°C, in particular from 850°C to 1400°C, more preferably from 1100°C to 1300°C.

[0032] The carbon monoxide provided as a process product of a partial oxidation can, for example, have been produced by a process for producing carbon monoxide for the provision of methanol, comprising at least the following steps

[0033] 1) Providing an oxygen-containing gas stream containing at least 50 wt% oxygen gas,

[0034] 2) partial oxidation of organic material (preferably organic material containing at least one polymeric organic compound), wherein said organic material is introduced into a reactor of a device and treated there at least by supplying said oxygen-containing gas stream and heat at at least 400°C to form a product gas, and the resulting product gas, optionally after at least one further partial oxidation step of the product gas, is discharged from the device as a carbon monoxide-containing product gas stream together with particulate solid dispersed therein;

[0035] 3) the carbon monoxide-containing product gas stream is fed to a cleaning process in which at least

[0036] 3-1) the carbon monoxide-containing product gas stream is fed to a washing step to separate solids, wherein

[0037] (i) water is brought into contact with the carbon monoxide-containing product gas stream, whereby the particulate solid dispersed in the carbon monoxide-containing product gas stream forms a slag and this slag is removed and discharged,

[0038] (ii) the carbon monoxide-containing product gas stream purified from particulate solids is discharged;

[0039] 3-2) a carbon monoxide-containing product gas stream purified from particulate solids by means of a washing step is fed to at least one water separation step in a drying step, water is separated off and the resulting carbon monoxide-containing product gas stream is discharged,

[0040] 3-3) a carbon monoxide-containing product gas stream purified by separation of water is fed to at least one carbon dioxide separation, carbon dioxide is separated and the resulting carbon monoxide-containing product gas stream and carbon dioxide are discharged;

[0041] 3-4) a carbon monoxide-containing product gas stream purified by separation of carbon dioxide is fed to at least one separation unit for the separation of carbon monoxide, a separation of carbon monoxide is carried out and the resulting carbon monoxide and a hydrogen gas-containing residual gas are discharged;

[0042] 3-5) optionally, a hydrogen gas-containing residual gas separated by means of said separation unit is fed to a residual gas treatment, hydrogen gas is separated and hydrogen gas and a tail gas are discharged.

[0043] A solid is known to be "particulate" if it exists in the form of a granular mixture of a large number of loose, solid particles of the substance in question, which in turn includes so-called grains. A grain is a term used to describe the particulate components of powders (grains are the loose, solid particles), dusts (grains are the loose, solid particles), granules (loose, solid particles are agglomerates of several grains), and other granular mixtures.

[0044] A "reactor" is a volume in which a chemical transformation, such as the partial oxidation of a polymeric, organic compound of a material, takes place. For partial oxidation, this could be, for example, the volume of a heated vessel containing the material.

[0045] The oxygen gas required for partial oxidation can be taken, for example, from a water electrolysis plant or an air separation plant. In a preferred embodiment of partial oxidation, the oxygen-containing gas stream is provided by electrolysis of water to obtain oxygen gas and hydrogen gas, and the oxygen gas from this electrolysis is used to provide the oxygen-containing gas stream. Water electrolysis can be carried out using state-of-the-art systems. Technical systems for alkaline water electrolysis as well as for polymer electrolyte-based electrolysis, so-called PEM electrolysis, are well known and commercially available. The principles of water electrolysis are described, for example, in Chapter 6.3.4 in Volkmar M. Schmidt's "Elektrochemische Verfahrenstechnik" (2003 Wiley-VCH-Verlag; ISBN 3-527-29958-0).

[0046] According to the invention, the organic solid material introduced into the reactor for partial oxidation preferably contains at least one polymeric organic compound. The partial oxidation should take place as uniformly and selectively as possible in the reactor. An increase in these parameters can be achieved if, within the scope of a preferred embodiment, the weight ratio of the oxygen gas contained in the oxygen-containing gas stream to the polymeric organic compound is introduced into the reactor within a weight ratio range of 0.4 to 1.0 to 1.2 to 1.0, preferably from 0.6 to 1.0 to 0.9 to 1.0, based on the time before introduction.

[0047] The partial oxidation of the introduced organic, solid material is carried out in a preferred embodiment at an absolute pressure of more than 1 bar, preferably at an absolute pressure in a range of 2 to 80 bar, particularly preferably at an absolute pressure in a range of 2 to 50 bar.

[0048] The partial oxidation of the organic solid material can be carried out in at least one of the following three reactors: entrained flow gasification reactor, fluidized bed gasification reactor and fixed bed gasification reactor.

[0049] For use in an entrained-flow gasification reactor, the organic solid material must be ground to a particle size with an average particle diameter X 50.s of < 0.1 mm (dust). It is fed into the reactor either pneumatically or as a slurry. The major limitation of this type of partial oxidation for chemical waste recycling is the grindability and pumpability of feedstocks from heterogeneous waste. Thermal treatment of biomass (torrefaction) at 200–300 °C under O2 exclusion is used to produce a "biochar" with grindability similar to that of hard coal. In another variant, upstream pyrolysis can be used to produce a pumpable pyrolysis oil. The oil obtained by waste pyrolysis can be partially oxidized either directly or in the form of a slurry mixed with the solid pyrolysis residue (pyrolysis coke).This process configuration was designed by Noell (Noell Conversion Process for the Recycling and Disposal of Waste, Jürgen Carl EF-Verl. für Energie- und Umwelttechnik, 1994. ISBN: 3924511829). Another variant is the use of a fluidized bed gasification reactor. The gasification of organic, solid material, especially waste, in fluidized bed reactors is widely known through the technologies EBARA (Showa Denko, Japan), ENERKEM (Enerkem, Edmonton, Canada), and the large-scale demonstration of high-temperature Winkler gas production (HTW) by Rheinbraun AG (now RWE) from 1993 to 1997 in Berrenrath, Germany. Pretreatment for feeding the organic material, or material containing polymeric organic compounds, into the reactor requires comminution to an average particle diameter X50.3 of 30-80 mm.The feed into the reactor vessel is via screw conveyors, limiting the gasifier pressure to a maximum of 10 bar. The technologies from ENERKEM and EBARA enable the gasification of high-calorific waste (plastic waste or plastic-rich refuse-derived fuels). Fluidized bed gasifiers are operated at mild temperatures of 700 - 950 °C, well below the ash melting point of the feedstock, to prevent caking and agglomeration in the reactor. A further advantage of this mild reactor temperature is the incomplete carbon conversion in the fluidized bed. Furthermore, the raw gas from fluidized bed gasification reactors typically contains significant amounts of methane and other hydrocarbons. To compensate for this and ensure a high syngas yield of H2 and CO, the ENERKEM and EBARA processes utilize a second high-temperature stage for partial oxidation (approx.1400 °C), located directly downstream of the fluidized bed, to melt fly ash and convert hydrocarbons in the first-stage product gas into the final carbon monoxide-containing product gas stream. ENERKEM calls this second stage a "thermoreformer," while EBARA calls it a "high-temperature gasification furnace." The high temperature of this second partial oxidation stage increases CO2 production.

[0050] The CO for the provision of methanol can also preferably originate as a process product from the conversion of methane from a biological source by means of partial oxidation in a conventional reformer process. In a preferred embodiment of such a provision, the CO is a process product of a conversion of at least methane from a biological source and water vapor (particularly preferably with the addition of CO2), with the addition of thermal energy at a temperature of at least 500°C, to carbon monoxide. A further suitable, sustainable reformer process with the addition of CO2 is described in the PCT patent application with the application number PCT / EP2022 / 052267, to which reference is expressly made in its entirety. This process relates to the production of carbon monoxide from methane from a biological source, water vapor, and CO2, comprising at least the steps

[0051] Synthesis of carbon monoxide in a reformer process in which methane from a biological source and water vapor are converted into carbon monoxide-containing product gas with the addition of at least CO2 and with the addition of heat energy at a temperature of at least 500°C,

[0052] Purification of the carbon monoxide-containing product gas obtained from the aforementioned synthesis, at least by separation of CO2 and optionally additionally by at least one separation selected from the separation of water, the separation of hydrogen or a combination thereof, to obtain carbon monoxide;

[0053] Providing CO2 for said addition to the aforementioned reforming process at least from said separation of CO2 from the aforementioned purification step.

[0054] In this case, it is again preferred if the heat energy supplied to the reformer process for the synthesis of carbon monoxide is provided by at least one method selected from (i) the combustion of fuel containing hydrogen generated by means of renewable energy, (ii) the combustion of fuel containing methane from a biological source, (iii) conversion of electrical energy generated from renewable energy into heat.

[0055] Experts understand "methane from biological sources" (also referred to as biomethane), as distinct from fossil methane, to be methane that is technically obtained from biomass through methane fermentation. Methane fermentation is known to be the anaerobic decomposition of organic matter by microorganisms. Methane from biological sources is produced, for example, in biogas plants, where both organic waste and renewable raw materials are fermented accordingly.

[0056] Experts define "renewable energy" as energy from a non-depletable energy source, such as wind power, hydropower, bioenergy (e.g., the generation of electricity from biogas or biomass), or solar energy. Therefore, wind power, solar energy, hydropower, or a mixture of these are particularly suitable renewable energy sources.

[0057] According to the invention, the methanol provided according to i) of process step a) according to the invention is preferably a process product of a conversion of CO, wherein this CO used in the conversion is a process product of at least a partial reduction of CO2 to CO, in particular selected from a reverse water-gas-shift reaction using H2 provided by electrolysis (preferably by water electrolysis, ie electrolysis of water), from an electrochemical reduction of CO2 to CO or from mixtures thereof.

[0058] In a particularly preferred embodiment of the process according to the invention, the methanol provided is provided as a process product of a conversion of CO, wherein the CO used in the conversion is a process product of at least a partial reduction of a gas stream which contains at least CO X with x = 1 or 2 and optionally hydrogen gas.

[0059] It has also proven highly preferred if, in one embodiment of the process, methanol is obtained by converting CO2 with or without hydrogen and used to produce methanol. It is particularly preferred if the conversion is an electrochemical reaction, a homogeneously catalyzed reaction, or a heterogeneously catalyzed reaction. In another embodiment, the CO2 used for this purpose also comes from another CCE source, for example, the CO2 emitted during the production of thermal energy or the CO2 from an external CCE source, e.g., an industrial exhaust gas.

[0060] According to the invention, an “electrochemical reaction” takes place by applying an electric current in the reaction medium (e.g. via at least one electrode immersed in the reaction medium) in the presence of at least one reactant (e.g. carbon dioxide).

[0061] A "catalyzed reaction" or "catalytic conversion" is defined as above (vide supra). According to the invention, a "homogeneously catalyzed reaction" takes place using a homogeneous catalyst, and a "heterogeneously catalyzed reaction" takes place using a heterogeneous catalyst.

[0062] A preferred CCE source is at least one "external CCE source" that contributes CO2 that is not emitted by the process according to the invention. An external CO2 source would be, for example, the CO2 generated during cement production, during ammonia synthesis, during fermentation, in the exhaust gases generated during fuel combustion (e.g., waste incineration), or CO2 extracted from the air.

[0063] In a particularly preferred embodiment of the process according to the invention, the carbon monoxide for methanol synthesis is produced from CO2 in a reverse water-gas shift (RWGS) reaction zone by at least one conversion of hydrogen and CO2 to carbon monoxide. Such an embodiment of carbon monoxide production is described, for example, in document WO 2021 / 089737 A, which is expressly incorporated herein by reference in its entirety.

[0064] A "reaction zone" is the part of a reaction space in which a chemical reaction, e.g., a reverse water-gas shift reaction, takes place. A "reaction space" is a volume in which the reactants involved in a chemical reaction are brought together and in which the chemical reaction takes place. For a chemical reaction, this could, for example, be the volume of a vessel in which a reactant, e.g., carbon dioxide in the case of a reverse water-gas shift reaction, and its reactant, hydrogen in the case of a reverse water-gas shift reaction, are present together and are reacted in the reaction zone. This volume could, for example, be located in a reactor.

[0065] The hydrogen gas used for the RWGS reaction is preferably provided by electrolysis, in particular by chlor-alkali electrolysis or water electrolysis, particularly preferably by water electrolysis. In each case, electrical energy generated from renewable energy (in particular hydropower, solar energy, or wind power) is preferably used.

[0066] In the particularly preferred process, the carbon monoxide provided for the provision of the methanol is a product of a process comprising at least the following steps:

[0067] Provision of a CCE gas stream,

[0068] Cleaning the CO2 gas stream from secondary components, in particular nitrogen oxides, sulphur compounds, dust, water, oxygen and HCl, optionally by means of adsorption, gas scrubbing or catalytic treatment to obtain purified carbon dioxide,

[0069] Feeding of hydrogen gas together with the purified CO2 gas stream into a RWGS reaction zone and conversion of the reactants according to the principle of the RWGS reaction to a product gas mixture of water vapor, CO and optionally by-products, in particular lower hydrocarbons, particularly preferably methane,

[0070] Separation of unreacted carbon dioxide from the gas mixture obtained from the separation of the RWGS reaction, in particular by means of amine scrubbing, and recycling of the unreacted carbon dioxide to the RWGS reaction,

[0071] Separation of the hydrogen not converted in the RWGS reaction from the gas mixture of carbon monoxide and hydrogen obtained after the separation, in particular using a cold box, and optionally recycling the hydrogen to the RWGS reaction,

[0072] Removal of the remaining carbon monoxide from the separation.

[0073] The CCE source for providing the CCE gas stream can be, for example, the CO2 emitted during the provision of heat energy for the process according to the invention (e.g. for the RWGS reaction), the CO2 obtained during air separation or CO2 from another external CCE source.

[0074] An "external CCE source" contributes CO2 that is not emitted by the process according to the invention or its embodiments. An external CO2 source would be, for example, the CO2 produced in the exhaust gas during cement production or during the combustion of fuels (e.g., waste incineration), or CO2 extracted from the air. Within the scope of a preferred embodiment of the process according to the invention, this CO2 from an external CCE source is obtained by absorbing a CO2 portion from (i) process gases or exhaust gases selected from at least one process selected from cement production, H2 production, or combustion, and / or (ii) from air by introducing it into alkali metal hydroxide solution, for example, potassium hydroxide solution. This produces potassium bicarbonate, which can subsequently be thermally decomposed back into CO2 and potassium hydroxide solution. The CO2 released in this process is then fed to the process according to the invention for the synthesis of carbon monoxide.

[0075] The RWGS reaction is preferably carried out in the reaction zone at a temperature > 650°C, particularly preferably > 700°C, most preferably > 750°C.

[0076] The RWGS reaction is preferably carried out in the presence of at least one catalyst. This is particularly preferably selected from at least one compound from the group:

[0077] (I) Mixed metal oxides of the formula A(i. w.X )A' w A" x Bi. y.Z )B' y B" z O3-deita where:

[0078] A, A' and A" are independently selected from the group: Mg, Ca, Sr, Ba, Li, Na, K, Rb, Cs, Sn, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ti, Lu, Ni, Co, Pb, Bi and / or Cd; and

[0079] B, B' and B" are independently selected from the group: Cr, Mn, Fe, Bi, Cd, Co, Cu, Ni, Sn, Al, Ga, Sc, Ti, V, Nb, Ta, Mo, Pb, Hf, Zr, Tb, W, Gd, Yb, Mg, Li, Na, K, Ce and / or Zn; and

[0080] 0 < w < 0.5; 0 < x < 0.5; 0 < y < 0.5; 0 < z < 0.5 and - 1 < delta < I ;

[0081] (II) Mixed metal oxides of the formula A(i. w.X )A' w A" x Bi. y.Z )B' y B" z O3-deita where:

[0082] A, A' and A" are independently selected from the group: Mg, Ca, Sr, Ba, Li, Na, K, Rb, Cs, Sn, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ti, Lu, Ni, Co, Pb and / or Cd; and

[0083] B is selected from the group: Cr, Mn, Fe, Bi, Cd, Co, Cu, Ni, Sn, Al, Ga, Sc, Ti, V, Nb, Ta, Mo, Pb, Hf, Zr, Tb, W, Gd, Yb, Mg, Cd, Zn, Re, Ru, Rh, Pd, Os, Ir and / or Pt; and

[0084] B' is selected from the group: Re, Ru, Rh, Pd, Os, Ir and / or Pt; and B" is selected from the group: Cr, Mn, Fe, Bi, Cd, Co, Cu, Ni, Sn, Al, Ga, Sc, Ti, V, Nb, Ta, Mo, Pb, Hf, Zr, Tb, W, Gd, Yb, Mg, Cd and / or Zn; and

[0085] 0 < w < 0.5; 0 < x < 0.5; 0 < y < 0.5; 0 < z < 0.5 and - 1 < delta < 1 ;

[0086] (III) mixtures of at least two different metals M1 and M2 on a support comprising an oxide of Al, Ce and / or Zr doped with a metal M3; where: M1 and M2 are independently selected from the group: Re, Ru, Rh, Ir, Os, Pd and / or Pt; and

[0087] M3 is selected from the group: Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu;

[0088] (IV) Mixed metal oxides of the formula LOx(M( y / Z )Al(2- y / z)O3)z; where:

[0089] L is selected from the group: Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, Sn, Pb, Pd, Mn, In, Ti, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu; and

[0090] M is selected from the group: Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Zn, Cu, Ag and / or Au; and

[0091] 1 < x < 2; 0 < y < 12; and 4 < z < 9;

[0092] (V) Mixed metal oxides of the formula LO ALOs^; where:

[0093] L is selected from the group: Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, Sn, Pb, Mn, In, Ti, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu; and

[0094] 4 < z < 9;

[0095] (VI) oxide catalyst comprising Ni and Ru.

[0096] (VII) metal M1 and / or at least two different metals M1 and M2 on and / or in a support, wherein the support is a carbide, oxycarbide, carbonitride, nitride, boride, silicide, germanide and / or selenide of the metals A and / or B; where:

[0097] Ml and M2 are independently selected from the group: Cr, Mn, Fe, Co, Ni, Re, Ru, Rh, Ir, Os, Pd, Pt, Zn, Cu, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and / or Lu; and

[0098] A and B are independently selected from the group: Be, Mg, Ca, Sc, I i, V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Hf, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and / or Lu; and / or

[0099] Reaction products of (I), (II), (III), (IV), (V), (VI) and / or (VII) in the presence of carbon dioxide, hydrogen, carbon monoxide and / or water at a temperature of > 700 °C.

[0100] In an equally preferred embodiment of the process, the methanol provided for the provision of hexamethylenediamine in the process according to the invention is provided from carbon monoxide, the carbon monoxide being a product of an electrochemical partial reduction of carbon dioxide to carbon monoxide. In this embodiment, to provide CO, a CO2 gas stream is introduced into an electrolysis device and reduced to carbon monoxide at an electrode, preferably at a gas diffusion electrode (particularly preferably using electrical energy generated from renewable energy). This electrochemical partial reduction is also referred to below as CO2 electrolysis.

[0101] CO2 electrolysis, for example, can be a high-temperature electrolysis process, which operates at temperatures exceeding 600°C, possibly with the addition of water to produce synthesis gas. High-temperature electrolysis processes are generally well-known and commercially available, for example, from Haldor Topsoe, eCOs®. During high-temperature electrolysis, oxygen is produced at the anode.

[0102] If the CCE electrolysis is operated as low-temperature electrolysis, the electrolysis takes place at a temperature below 150°C.

[0103] In all CCE electrolysis processes, the CO2 gas is fed into the cathode chamber.

[0104] In the case of low-temperature electrolysis, CO2 is converted, in particular, at a gas diffusion electrode to carbon monoxide and optionally hydrogen. Those skilled in the art are familiar with electrodes and a method for carrying out the electrochemical reduction of CO2, for example, from WO 2021 / 069470 A. The electrochemical reduction of CO2 is preferably carried out according to a process described in WO 2021 / 069470 A. This document is expressly incorporated herein by reference in its entirety. In this preferred electrolytic process for producing carbon monoxide, carbon monoxide, optionally hydrogen, and chlorine are obtained by the electrochemical conversion of carbon dioxide and alkali metal chloride solution.This preferred electrolysis process is characterized in that the carbon dioxide is electrochemically reduced at a gas diffusion electrode as cathode in an aqueous alkali chloride-containing solution as catholyte and at the same time chlorine is anodically generated from an aqueous alkali chloride-containing solution as anolyte, wherein the alkali salt of carbonic acid formed in the catholyte, selected from alkali carbonate, alkali hydrogen carbonate or mixtures thereof, is then reacted with hydrogen chloride to form carbon dioxide and alkali chloride and the carbon dioxide released in this process is returned to the cathode compartment to the gas diffusion electrode and the alkali chloride generated is returned optionally to the anode compartment and / or to the cathode compartment.

[0105] According to known principles, an MEA (membrane electrode assembly) concept can also be used for low-temperature electrolysis. A catalyst is applied to the membrane. A gas diffusion layer placed in front of it regulates gas and liquid transport. This can be done on both the anode and cathode sides. Furthermore, it is possible to place a gas diffusion electrode in direct contact with the membrane. The gas diffusion electrode used can be installed in the electrolysis cell in a zero-gap or finite-gap arrangement. A preferred arrangement for low-temperature electrolysis of CO2 is described in WO 2020 / 057998 A1, to which reference is expressly made in its entirety.

[0106] An excess of CO2 can be fed into the cathode chamber, or rather the gas diffusion electrode installed therein. Excess means introducing more CO2 than is necessary for stoichiometric conversion due to the flowing electric current. Thus, a gas mixture consisting of unreacted CO2, CO, and H2 emerges from the cathode chamber.

[0107] In a further embodiment of CO2 electrolysis, it is preferred if the electrical energy used for this purpose is electrical energy produced from renewable energy, in particular electrical energy produced from wind power, solar energy or hydropower.

[0108] If the carbon monoxide used to provide the methanol is a process product of at least one of the aforementioned processes, at least one of the processes known to the person skilled in the art can be used to convert the CO to methanol, starting from CO-containing synthesis gas.

[0109] If CO is not already produced directly as a mixture with sufficient hydrogen as synthesis gas from step ii-1), if a sufficient amount of hydrogen gas is not available, hydrogen gas is added to the CO before conversion to methanol to obtain synthesis gas. This hydrogen gas, which is additionally added to the CO as part of the preparation of methanol, is preferably provided by electrolysis, in particular by chlor-alkali electrolysis or water electrolysis. Water electrolysis can be carried out using state-of-the-art systems. Technical systems for alkaline water electrolysis as well as for polymer electrolyte-based electrolysis, so-called PEM electrolysis, are well known and commercially available. The principles of water electrolysis are described as an example in Chapter 6.3.4 in Volkmar M. Schmidt's "Elektrochemische Verfahrenstechnik" (2003 Wiley-VCH-Verlag; ISBN 3-527-29958-0).In a further embodiment, it is preferred if the electrical energy used for the electrolysis to produce hydrogen is electrical energy produced from renewable energy, in particular electrical energy produced from wind power, solar energy or hydropower.

[0110] Particularly preferred is an embodiment in which the methanol to be provided for the process according to the invention was produced as a process product using renewable energy, preferably at a geographical location with good availability of renewable energy, in order to subsequently provide this methanol for the process according to the invention either by delivery via transport in containers or via methanol stream as part of a continuous process. For provision as part of a continuous process, the methanol production is preferably in fluid communication with the production of hexamethylenediamine, e.g., via a pipeline.

[0111] Methanol production plants can be licensed on the market, for example, from Air Liquide, Johnson Matthey, and other companies. An overview of conventional methanol production from synthesis gas is published, for example, in Ott et al., Methanol in: Ullmann's Encyclopedia of Industrial Chemistry, 2012, Wiley-VCH Verlag, Weinheim (doi 10.1002 / 14356007.al6_465.pub3), which is expressly incorporated by reference.

[0112] The methanol provided as described above according to step a) i) is converted to propene in step a) ii) of the process according to the invention for providing the hexamethylenediamine by a process comprising at least the following steps:

[0113] Providing propene as a product of a process comprising at least the following steps: ii-1) converting the previously provided methanol to a product mixture containing dimethyl ether, water, and methanol; ii-2) converting starting material containing dimethyl ether, water, and methanol, each from the aforementioned product mixture, to propene at a temperature of more than 200°C by contact with a catalyst, preferably with at least one zeolite compound.

[0114] Steps ii-1) and ii-2) are part of the methanol-to-propylene process (also called the MTP process). The MTP process was first developed by Lurgi.

[0115] In an MTP process, for example, gaseous methanol is converted over a catalyst in a reactor to a product mixture containing dimethyl ether, water, and methanol as defined in step ii-1) of the process according to the invention. Suitable reactors for this purpose include, for example, a fixed-bed reactor or a fluidized-bed reactor.

[0116] In a preferred embodiment of the process according to the invention, the conversion of the methanol provided according to step a) ii-1) is carried out by contacting the methanol, preferably the methanol in the gas phase, with a catalyst.

[0117] A particularly preferred catalyst for converting the methanol in step ii-1) is, for example, AbOs granulate, as described in the publications EP 0 448 000 B1 or DE 197 23 363 A1. Before converting the methanol in step a) ii-1), the methanol provided is preferably brought to a temperature in the range from 200°C to 350°C, and the conversion is carried out using this appropriately tempered methanol. The product mixture comprising dimethyl ether, methanol, and water preferably has a temperature of 350°C to 450°C after the conversion.

[0118] The product mixture from step ii-1), in particular in the form of a gas stream, is introduced, optionally after carrying out optional purification steps, as starting material for step ii-2), for example, into a further reactor and converted there to propene over a catalyst. Suitable catalysts include, for example, the catalyst marketed by Clariant under the trade name MTPROP®, or a zeolite compound as a catalyst, as described, for example, in US Pat. No. 7,015,369 B2, column 1, lines 43-52, and in Examples 1 and 2 thereof. Preferably, in a further embodiment of the process according to the invention, the starting material is converted to propene by contact with a zeolite compound as a catalyst.

[0119] It is preferred if in step ii-2) the starting material is reacted at a temperature of 350°C to 600°C, in particular at a temperature of 380°C to 550°C.

[0120] The propene provided by step ii-2) of the process according to the invention is reacted with ammonia to form acrylonitrile according to step iii), optionally after the separation of secondary constituents. According to the invention, for the provision of the hexamethylenediamine, it is sufficient if the acrylonitrile used for this purpose is an actual process product of at least steps i), ii), and iii) mentioned under a). This means that for the implementation of the step of providing the hexamethylenediamine, it is sufficient to simply withdraw the acrylonitrile produced in this manner as a raw material from a storage tank or a feed line as part of a delivery in order to feed it to at least step a) iv) of the process according to the invention.In this case, the hexamethylene diisocyanate producer, as the executor of the process according to the invention, does not itself carry out the steps i), ii) and iii) mentioned under a) of the process according to the invention for the preparation of the acrylonitrile, but only ensures that the hexamethylenediamine provided has been prepared from acrylonitrile which has been synthesized by applying at least the steps i), ii) and iii) mentioned under a) and is thus the actual process product thereof.

[0121] For the synthesis of acrylonitrile from propene, ammonia is first provided as the actual process product of a process comprising at least the following steps: iii- 1-1) Providing hydrogen gas by electrolysis of water, preferably using electrical energy generated from renewable energy; iii-1-2) Conversion of the provided hydrogen gas with gaseous nitrogen to form ammonia.

[0122] The electrolysis of water, which is carried out in step iii-1-1) to synthesize the hydrogen gas to be produced, can be carried out using state-of-the-art systems. Technical systems for alkaline water electrolysis as well as for polymer electrolyte-based electrolysis, known as PEM electrolysis, are well-known and commercially available. The principles of water electrolysis are described, for example, in Chapter 6.3.4 of Volkmar M. Schmidt's "Electrochemical Process Engineering" (2003, Wiley-VCH-Verlag; ISBN 3-527-29958-0).

[0123] The ammonia is produced according to step a) iii-1-2) starting from nitrogen and the hydrogen provided in the previous step a) iii-1-1) in a manner well known to the person skilled in the art, as described, for example, by the Haber-Bosch process using known reactor technologies and designs for this process, to which reference is expressly made in full here.

[0124] For the supply and production of ammonia, it has proven preferable for the nitrogen used to be provided by air separation. Air separation processes and suitable nitrogen production plants are state-of-the-art and commercially available.

[0125] The propene provided by at least the aforementioned process steps is then oxidatively reacted with the provided ammonia to form acrylonitrile, preferably by the so-called SOHIO process (for example, according to US Pat. No. 2,904,580 A). According to the invention, it is preferred if the reaction of the provided ammonia with the propene according to step a) iii-2) takes place using atmospheric oxygen at a temperature of 350°C to 550°C.

[0126] In a further embodiment of the process for preparing the acrylonitrile provided, the reaction is particularly preferably carried out at a relative pressure of 40 to 220 kPa.

[0127] It has proven advantageous to allow the reaction of the provided ammonia with the propene according to step a) iii-2) to take place over a molybdate- and / or antimonate-based catalyst. In this embodiment, it is again preferred if the aforementioned temperature is maintained and the reaction is carried out using oxygen, preferably atmospheric oxygen.

[0128] The acrylonitrile produced according to step iii-2) of the process according to the invention is electrochemically converted to adiponitrile (CAS No. 111-69-3, also known as adipic acid dinitrile) according to step iv). According to the invention, for the provision of the hexamethylenediamine, it is sufficient if the adiponitrile used is an actual process product of at least steps i), ii), iii), and iv) mentioned under a). This means that for the implementation of the step of providing the hexamethylenediamine, it is sufficient to simply remove the adiponitrile produced in this manner as a raw material from a storage container or a feed line in order to feed it to at least step a) v) of the process according to the invention.In this case, the hexamethylene diisocyanate producer, as the executor of the process according to the invention, does not carry out the steps i), ii), iii) and iv) mentioned under a) of the process according to the invention for the preparation of the adiponitrile itself, but only ensures that the hexamethylenediamine provided has been prepared from adiponitrile which has been synthesized by applying at least the steps i), ii), iii) and iv) mentioned under a) and is thus the actual process product thereof.

[0129] The said adiponitrile must be an actual process product of at least the steps

[0130] Introducing a mixture containing water, said acrylonitrile from step a) iii-2), and at least one electrolyte salt into the cathode compartment of an electrolysis cell and contacting the mixture with a cathode to which an electric current is applied; cathodic hydrodimerization of the acrylonitrile to form an adiponitrile-containing product mixture;

[0131] Extraction of the adiponitrile-containing product mixture from the cathode compartment of the electrolysis cell and optional purification of the adiponitrile. These steps are carried out, for example, as described in the patent US 3,193,480 A, to which reference is expressly made in its entirety.

[0132] To prepare the mixture, at least water, said acrylonitrile, and at least one electrolyte salt are blended. This preferably forms an emulsion of acrylonitrile-containing droplets in water.

[0133] In a preferred embodiment, at least one quaternary ammonium salt, in particular at least one quaternary ammonium sulfonate, is suitable as the electrolyte salt in the cathode compartment of the electrolysis cell. A particularly preferred electrolyte salt is selected from at least one electrolyte salt from the group consisting of tetraalkylammonium salts, tetraalkanolammonium salts, dialkyl-dialkanolammonium salts,

[0134] Alkyltrialkanolammonium salts, trialkylalkanolammonium salts,

[0135] Trialkylbenzylammonium salts, quaternary N-heterocyclo-N-alkylammonium salts, with the sulfonic acid salts thereof being more particularly suitable. Particularly preferred alkyl groups of the ammonium cations of the aforementioned salts are (Ci-Ce)-alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl. Particularly preferred alkanol groups are (Ci-Ce)-hydroxyalkyl groups such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, and 4-hydroxypropyl. Particularly preferred N-heterocyclo groups include, for example, piperidinium, morpholinium, and pyrrolidinium. Particularly suitable anions of the quaternary ammonium salts are chloride, fluoride, sulfates, phosphates, and sulfonates.

[0136] The tetraalkylammonium salts of aryl- or alkylarylsulfonic acids are particularly preferred electrolyte salts. Particularly preferred sulfonate anions of the quaternary ammonium salts preferably usable as electrolyte salts are benzenesulfonate, o-toluylsulfonate, m-toluylsulfonate, o-toluylsulfonate, m-toluylsulfonate, p-toluylsulfonate, o-cumylsulfonate, m-cumylsulfonate, p-cumylsulfonate, alpha-naphthylsulfonate, beta-naphthylsulfonate, p-xylylsulfonate, or mixtures thereof. Particularly preferred sulfate anions are selected from at least one anion with an organic radical that is analogous to the organic radicals of the aforementioned sulfonate anions.

[0137] In a highly preferred embodiment, at least one electrolyte salt is selected from tetramethylammonium chloride, tetraethylammonium chloride, tetra(n-butyl)ammonium chloride, tetraethylammonium p-toluylsulfonate, tetraethylammonium o-toluylsulfonate, tetraethylammonium m-toluylsulfonate, tetraethylammonium benzenesulfonate; tetraethylammonium o-, m- or p-cumylsulfonate or o-, m-, or p-ethylbenzenesulfonate; N,N-dimethylpiperidinium, o-, m- or p-toluylsulfonate or o-, m- or p-biphenylsulfonate; tetrabutylammonium alpha- or beta-naphthylsulfonate or o-, m- or p-toluylsulfonate; tetrapropylammonium o-, m- or p-amylbenzenesulfonate or alpha-ethyl-beta-naphthylsulfonate; Tetra(2-hydroxylethyl)ammonium o-, m- or p-cumyl sulfonate or o-, m- or p-toluyl sulfonate; tetra(4-hydroxybutyl)ammonium benzenesulfonate or p-xylyl-3-sulfonate;Tetrapentylammonium o-, m- or p-toluylsulfonate or o-, m- or p-hexylbenzenesulfonates, tetrapentylammonium p-cumyl-3-sulfonate or benzenesulfonate; Methyltriethylammonium o-, m- or p-toluylsulfonate or mesityl-2-sulfonate; Trimethylethylammonium o-xylyl-4-sulfonate or o-, m- or p-toluylsulfonate; triethylpentylammonium alpha- or beta-naphthylsulfonate or o-, m- or p-butylbenzenesulfonate, trimethyl-hydroxyethylammonium benzenesulfonate or o-, m- or p-toluylsulfonate; N,N-diethylpiperidinium or N-methylpyrrolidinium o-, m- or p-hexylbenzenesulfonate or o-, m- or p-toluylsulfonate, N,N-di-isopropyl or N,N-dibutylmorpholinium, o-, m- or p-toluylsulfonate or o-, m- or p-biphenylsulfonate, or mixtures of the aforementioned salts.;

[0138] In a further preferred embodiment, it has proven advantageous if the mixture introduced in step a) iv) has a pH in the range from pH 7 to pH 10, in particular from pH 7 to pH 9.5. It is further particularly preferred if the pH of the mixture in the cathode compartment is determined by the normality of the anolyte in the anode compartment of the electrolysis cell and the formal migration of H + -ions from the anode compartment to the cathode compartment. For this purpose, the anolyte in the anode compartment of the electrolysis cell preferably has a normality in the range of 0.4 to 1.2.

[0139] In a preferred embodiment, the electrolysis cell in which the electrochemical hydrodimerization takes place has a cathode compartment and an anode compartment separated from each other by a membrane. Suitable membranes for this purpose include those mentioned in US Pat. No. 3,193,480 A, or are commercially available, e.g., under the trade name Nafion® 115.

[0140] In a further embodiment of the process, it is preferred if an electric current with a current density of 15 to 40 A / dm 2 , particularly preferably at a voltage of 5 to 20 volts.

[0141] It is further preferred according to the invention if the cathodic hydrodimerization of the acrylonitrile to adiponitrile is carried out by an applied electric current which was actually generated using renewable energy, in particular selected from wind power, hydropower, solar energy or mixtures thereof.

[0142] The adiponitrile provided according to step a) iv) is converted to hexamethylenediamine by catalytic hydrogenation with hydrogen by processes known to those skilled in the art (preferably at a temperature in the range from 100°C to 200°C and an operating pressure in the range from 28 to 41 MPa). The hydrogenation is more preferably carried out in the liquid phase, optionally with the addition of ammonia as a heat transfer medium. Suitable catalysts for the catalytic hydrogenation of adiponitrile are, in particular, cobalt-containing catalysts, as described, for example, in US 3,232,888 A, US 3,821,305 A, US 3,773,832 or US 4,598,058 A. Iron-containing catalysts, as described, for example, in US 3,696,153 A or US 4,587,228 A, are also usable.

[0143] In step b) of the process according to the invention, phosgene is produced. In step b) i) of the process according to the invention, carbon monoxide is first prepared, which is an actual process product of at least the methods listed in step b) i).

[0144] For the provision of carbon monoxide, it is sufficient within the meaning of the invention if the carbon monoxide is a process product of at least the methods listed in step b) i). This means that when carrying out the process according to the invention, it is sufficient for the step of providing carbon monoxide to simply remove said carbon monoxide as an actual process product of said steps as part of a delivery as raw material from a storage container or from a feed line. In this case, the hexamethylene diisocyanate producer, as the executor of the process according to the invention, does not carry out the production of the carbon monoxide itself, but merely ensures that the carbon monoxide provided was produced accordingly by a supplier and is an actual process product of at least the methods listed in step b) i).

[0145] Likewise, within the scope of one embodiment of the invention, it is possible for the above-mentioned steps for producing carbon monoxide to be carried out as integral steps of a process according to the invention in step b) i) by the hexamethylene diisocyanate producer itself to provide the carbon monoxide, and for the carbon monoxide obtained thereby to be fed to the phosgene production in step b) ii).

[0146] The embodiments mentioned in step b) i) of the partial reduction of CO2 to CO and the partial oxidation of organic material to CO, wherein at least one organic material is selected from at least one organic, solid compound, methane from a biological source, or mixtures thereof, have already been described under step a) i-1) (vide supra). These also apply accordingly to step b) i).

[0147] Furthermore, in step b) i), the carbon monoxide can originate from a partial oxidation of at least one monohydroxyalkyl compound, in particular methanol. This step is referred to below as catalytic decomposition. It is preferred if the monohydroxyalkyl compound is methanol and the methanol is a process product of at least the steps described under a) i). The embodiments described above under step a) i) must again be taken into account here (vide supra).

[0148] In the catalytic decomposition step of methanol, the methanol provided is, in a preferred embodiment, decomposed by contacting gaseous methanol with a catalyst and catalytically decomposing it to form carbon monoxide and, optionally, hydrogen gas. If the methanol is not in gaseous form for this purpose (e.g., when removed from a storage container), it is first subjected to evaporation. The energy input required for evaporation can be generated by using fossil fuels, such as natural gas, as an energy source.For the process according to the invention, heat energy is particularly preferably supplied to adjust the temperature required for evaporation. This heat energy is provided by at least one method selected from (i) the combustion of fuel containing hydrogen (gaseous H2) generated by renewable energy, (ii) the combustion of fuel containing methane from a biological source, or (iii) the conversion of electrical energy generated from renewable energy into heat. It is particularly preferred, in turn, if wind power, solar energy, hydropower, or mixtures thereof are used as the renewable energy.

[0149] For the catalytic decomposition, gaseous methanol is preferably passed over a catalyst whose active component contains at least one transition metal species. The person skilled in the art understands transition metal species to be all d-block elements and their chemical compounds. The catalyst is particularly preferably a transition metal species applied to a support. Most preferably, this is at least one transition metal species selected from group VII, VIII, or XI of the Periodic Table of the Elements, which in turn is preferably applied to a support. The catalytic decomposition of the methanol is preferably carried out at a temperature below 500°C, particularly preferably below 400°C. If energy input is necessary for the catalytic decomposition of methanol, this can be achieved by using fossil fuels, such as natural gas, as the energy source.To adjust the temperature required for the catalytic decomposition of methanol, the process according to the invention particularly preferably uses thermal energy provided by at least one method selected from (i) the combustion of fuel containing hydrogen (gaseous H2) generated by renewable energy, (ii) the combustion of fuel containing methane from a biological source, or (iii) the conversion of electrical energy generated from renewable energy into heat. It is particularly preferred, in turn, if wind power, solar energy, hydropower, or mixtures thereof are used as the renewable energy.

[0150] The catalytic decomposition of methanol is preferably carried out at a temperature of at least 200°C. It is again preferred if the temperature for the catalytic decomposition of methanol is set at 200 to below 500°C, particularly preferably at 200 to below 400°C.

[0151] The catalytic decomposition of methanol is preferably carried out at an absolute pressure of less than 50 bar, particularly preferably less than 40 bar.

[0152] The product gas obtained from the catalytic decomposition contains, in addition to carbon monoxide, often also methanol, carbon dioxide, hydrogen, and water, as well as possibly by-products, which may include ethers (dimethyl ether), alcohols (ethanol), aldehydes, or esters. Preferably, the product gas obtained from the catalytic decomposition is subjected to a purification step in a preferred, additional process step before being converted with chlorine to phosgene, in which methanol, carbon dioxide, hydrogen, and water, as well as any by-products, are separated from the carbon monoxide.

[0153] The carbon monoxide provided for step b) ii) is preferably freed from secondary components and purified before phosgene production. For this purpose, the carbon monoxide is preferably fed to a carbon dioxide separation unit in a CCE separation unit, where the CO2 is separated.

[0154] The CO2 separation unit, and thus the separation of CO2, can be implemented as an "amine scrubbing" process, whereby the carbon monoxide-containing product gas from the reformer process undergoes, in particular, the generally known scrubbing of the gas mixture according to the principle of chemisorption with amines such as monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), or diglycolamine (DGA), which achieves a high purity of the purified gas mixture in an absorption column. In a further preferred embodiment of the process according to the invention, water is separated from the carbon monoxide produced.

[0155] In a further preferred embodiment of the process, the carbon dioxide is separated after water has been separated from the provided carbon monoxide. For this purpose, the provided carbon monoxide is first fed to a water separation unit, where the water is separated, and the dry carbon monoxide-containing product gas obtained after the water separation is fed to a CO2 separation unit, where the CO2 is separated. In the water separation unit, the provided carbon monoxide is cooled to separate the water, for example, and the water is separated, for example as condensate.

[0156] A preferred variant of the process according to the invention is a process in which the carbon monoxide provided (preferably previously freed from water and CO2) is introduced into an H2-CO separation unit in which hydrogen is separated. This produces at least one gas stream whose gas contains at least 95 vol.% carbon monoxide, more preferably at least 99 vol.% carbon monoxide, at 25°C and 1013 mbar. Said introduced carbon monoxide is preferably first separated into two gas streams in the H2-CO separation unit. This produces a gas in the form of a gas stream containing at least 95 vol.% (preferably at least 99 wt.%) carbon monoxide, and a further gas in the form of a gas stream whose largest constituent is hydrogen and contains, among other things, carbon monoxide. The further gas is also referred to as the residual gas from the H2-CO separation or, if no residual gas treatment takes place, as the tail gas.A H2-CO separation unit operating according to this separation principle is the so-called cold box. The hydrogen-containing residual gas from the H2-CO separation can be recycled into methanol production.

[0157] The carbon monoxide obtained (optionally after purification) is reacted with chlorine to form phosgene in a next process step b) ii), preferably over a catalyst. The catalyst is particularly preferably activated carbon.

[0158] For the provision of chlorine for the synthesis of phosgene carried out in this embodiment, the production of chlorine gas from electrochemical oxidation after hydrochloric acid electrolysis with a gas diffusion electrode (also referred to as the HCl ODC electrolysis process (ODC stands for oxygen depleting electrode, an ODC used, for example, is the so-called ODC (oxygen depleting cathode)); suitable electrolysis cells cf. US, 6022, 634 A, WO 03 / 31690 A1), the production of chlorine gas from hydrochloric acid diaphragm electrolysis (cf. EP 1 103 636 A1), the production of chlorine gas from thermocatalytic gas phase oxidation (cf. WO 2012 / 025483 A2), and the production of chlorine from chlor-alkali electrolysis (cf. WO 2009 / 007366 A2) are sufficiently known to the person skilled in the art. The contents of the aforementioned documents cited in connection with the production of chlorine gas are expressly and fully referred to.In a preferred variant of this embodiment of the process, the chlorine required for the synthesis of phosgene is produced electrolytically, in particular by electrochemical oxidation after hydrochloric acid electrolysis with a gas diffusion electrode, by electrochemical oxidation after hydrochloric acid diaphragm electrolysis, or by electrochemical oxidation after chlor-alkali electrolysis. It is particularly preferred if said electrochemical oxidation is carried out using electricity generated from renewable energy, in particular from renewable energy in the form of wind power, solar energy, or hydropower.

[0159] In step c) of the process according to the invention, phosgene is reacted with the hexamethylenediamine prepared in step a), and hexamethylene diisocyanate is produced. Corresponding processes and apparatus for reacting phosgene with organic amine compounds are known to those skilled in the art, for example from WO 2017 / 093215 A1, which is expressly incorporated herein by reference in its entirety. It has proven advantageous in the context of the present process if, in a preferred embodiment, the phosgene and the hexamethylenediamine are reacted in the gas phase to obtain hexamethylene diisocyanate. The phosgenation of amines in the gas phase is known per se and can be carried out, for example, as described in EP 0 289 840 B1, EP 1 319 655 A2, EP 1 555 258 A1, EP 1 275 639 A1, EP 1 275 640 A1, EP 1 449 826 A1, EP 1 754 698 B1, DE 10 359 627 A1, DE 10 2005 042392 A1 or WO 2017 / 093215 A1.

[0160] A second subject of the invention is a process for producing polyurethane, comprising at least the following steps:

[0161] Providing hexamethylene diisocyanate, which is a process product of the process of the first subject matter of the invention;

[0162] Providing at least one organic polyol;

[0163] Reaction of said hexamethylene diisocyanate with said organic polyol to form polyurethane.

[0164] Organic polyols are organic compounds with at least two hydroxyl groups. These are preferably selected from polyester polyols, polyether polyols, polycarbonate polyols, polyetherester polyols, polyacrylate polyols, polyester polyacrylate polyols, or mixtures thereof, particularly preferably selected from the group of polyether polyols and / or polyester polyols.

[0165] In a preferred embodiment, the process for producing polyurethane is characterized in that the hexamethylene diisocyanate is provided using a multi-component system according to the third subject matter of the invention (vide infra). A third subject matter of the invention is a multi-component system for producing hexamethylene diisocyanate according to a production process of the first subject matter of the invention, comprising i) a volume filled with hexamethylenediamine, which is a process product of step a) of the process according to the first subject matter of the invention; ii) a volume filled with carbon monoxide, which is a process product of step b) i-1) of the process according to the first subject matter of the invention; iii) at least one electrolysis device for producing chlorine;iv) at least one reactor for producing phosgene, the reactor having at least one inlet for chlorine in fluid communication with the electrolysis device for producing chlorine, and at least one inlet for carbon monoxide in fluid communication with the volume filled with the carbon monoxide; v) at least one reactor for producing hexamethylene diisocyanate, which contains at least one inlet for said phosgene and at least one inlet for said hexamethylenediamine, the inlet for said phosgene being in fluid communication with the reactor for producing phosgene and the inlet for said hexamethylenediamine being in fluid communication with the volume of said hexamethylenediamine;

[0166] All embodiments of step a) of the process according to the invention for preparing hexamethylene diisocyanate are also valid for the multicomponent system mutatis mutandis.

[0167] All embodiments of step b) of the process according to the invention for preparing hexamethylene diisocyanate are also valid for the multicomponent system mutatis mutandis.

[0168] A fourth aspect of the invention is therefore the use of methanol as a raw material for producing the hexamethylene residue of hexamethylene diisocyanate. A corresponding use is preferred, which is carried out by a process according to the first aspect of the invention.

Claims

P a t e n t a n s p r ü c h e 1. A process for the preparation of hexamethylene diisocyanate for the production of polyurethane, comprising at least the steps: a) Providing hexamethylenediamine, which is a process product of a process comprising at least the following steps: i) Providing methanol, which is a process product of a process with at least the following steps: i-1) Providing carbon monoxide as a process product of at least one partial reduction of CO2 to CO and / or as a process product of at least one partial oxidation of organic material to CO, wherein at least one organic material is selected from at least one organic, solid compound, methane from a biological source or mixtures thereof; i-2) Conversion of the provided carbon monoxide to methanol; ii) Synthesis of propene from previously provided methanol by at least the following steps: ii-1) Conversion of the previously provided methanol to a Product mixture containing dimethyl ether, water and methanol; ii-2) Conversion of starting material containing dimethyl ether, water and methanol, each from the aforementioned product mixture, at a temperature of more than 200°C by contact with a catalyst, preferably with at least one zeolite compound as catalyst, to propene; iii) Synthesis of acrylonitrile from the propene by at least the following steps: iii-1) Provision of ammonia, which is a process product of a A process comprising at least the following steps: iii- 1-1) providing hydrogen gas as a product of water electrolysis, preferably using electrical energy generated from renewable energy; iii- 1-2) reacting the provided hydrogen gas with gaseous nitrogen to form ammonia; iii-2) reacting the propene with the ammonia provided to form acrylonitrile; iv) synthesizing adiponitrile from the acrylonitrile by at least the following steps: Introducing a mixture containing water, said acrylonitrile, and at least one electrolyte salt into the cathode compartment of an electrolysis cell and contacting the mixture with a cathode to which an electric current is applied; cathodic hydrodimerization of the acrylonitrile to form an adiponitrile-containing product mixture; Extraction of the adiponitrile-containing product mixture from the cathode compartment of the electrolysis cell and optional purification of the adiponitrile; v) synthesis of hexamethylenediamine from the adiponitrile by at least the following steps: Providing hydrogen gas as a product of electrolysis, preferably using electrical energy generated from renewable energy; Hydrogenation of the adiponitrile with the hydrogen gas to form hexamethylenediamine; b) Production of phosgene by at least the following process steps: i) Provision of carbon monoxide as a process product of at least one partial reduction of CO2 to CO and / or as a process product of at least one partial oxidation of organic material to CO, wherein at least one organic material is selected from at least one organic, solid compound, an organic, liquid monohydroxyalkyl compound, methane from a biological source or mixtures thereof; ii) Reaction of the carbon monoxide from step i) with chlorine to form phosgene; c) Reaction of the provided hexamethylenediamine with the phosgene to form hexamethylene diisocyanate.

2. Process according to claim 1, characterized in that the carbon monoxide provided in step a) i-1) and / or in step b) i-1) is each independently a process product of at least one partial reduction of a gas stream containing at least CO X with x = 1 or 2 and optionally hydrogen gas.

3. Process according to one of claims 1 or 2, characterized in that the carbon monoxide provided in step a) i-1) and / or in step b) i-1) is each independently a process product of at least one partial reduction of CO2 to CO, in particular selected from a reverse water-gas shift reaction using H2 provided by electrolysis, from an electrochemical reduction of CO2 to CO or from mixtures thereof.

4. Process according to one of the preceding claims, characterized in that the carbon monoxide provided in step a) i-1) and / or in step b) i-1) is each independently a process product of at least one reverse water-gas shift reaction using H2 provided by electrolysis or is provided from an electrochemical reduction of CO2 to CO or from mixtures thereof, with the proviso that in each case electrical energy produced from renewable energy is used.

5. Process according to one of the preceding claims, characterized in that the conversion of the methanol according to step a) ii-1) is carried out by contacting the methanol, preferably the methanol in the gas phase, with a catalyst.

6. Process according to one of the preceding claims, characterized in that for the conversion of the methanol in step a) ii-1), said methanol provided has a temperature in a range from 200°C to 350°C.

7. Process according to one of the preceding claims, characterized in that the conversion of the starting material according to step a) ii-2) takes place at a temperature of 350°C to 600°C, in particular of 380°C to 550°C.

8. Process according to one of the preceding claims, characterized in that the reaction of the ammonia provided with the propene according to step a) iii-2) is carried out using atmospheric oxygen at a temperature of 350°C to 550°C.

9. Process according to one of the preceding claims, characterized in that the reaction of the ammonia provided with the propene according to step a) iii-2) takes place on a molybdate- and / or antimonate-based catalyst.

10. Process according to one of the preceding claims, characterized in that the electrolyte salt in the cathode compartment of the electrolysis cell is selected from at least one quaternary ammonium salt, in particular at least one quaternary ammonium sulfonate.

11. Process according to one of the preceding claims, characterized in that in step a) iv) the electrolysis cell has a cathode compartment and an anode compartment which are separated from each other by a membrane.

12. Process according to one of the preceding claims, characterized in that in step a) iv) the mixture introduced has a pH in the range from pH 7 to pH 10, in particular from pH 7 to pH 9.

5.

13. A process according to any one of the preceding claims, characterized in that an electric current with a current density of 15 to 40 A / dm 2 is present.

14. A process for producing polyurethane, comprising at least the following steps: Providing hexamethylene diisocyanate which is a process product of the process according to any one of claims 1 to 13; Providing at least one organic polyol; Reaction of said hexamethylene diisocyanate with said polyol to form polyurethane.

15. The method according to claim 14, characterized in that the provision of the hexamethylene diisocyanate is carried out using a multi-component system according to claim 16.

16. A multi-component system for producing hexamethylene diisocyanate according to a production process of claims 1 to 13, comprising i) a volume filled with hexamethylenediamine, which is a process product of step a) of the process according to any one of claims 1 to 13; ii) a volume filled with carbon monoxide, which is a process product of step b) i-1) of the process according to any one of claims 1 to 13; iii) at least one electrolysis device for producing chlorine; iv) at least one reactor for producing phosgene, wherein the reactor has at least one inlet for chlorine, which is in fluid communication with the electrolysis device for producing chlorine, and at least one inlet for carbon monoxide, which is in fluid communication with the volume filled with the carbon monoxide;v) at least one reactor for producing hexamethylene diisocyanate, which contains at least one inlet for said phosgene and at least one inlet for said hexamethylenediamine, wherein the inlet for said phosgene is in fluid communication with the reactor for producing phosgene and the inlet for said hexamethylenediamine is in fluid communication with the volume of said hexamethylenediamine; 7. Use of methanol as a raw material for producing the hexamethylene residue of hexamethylene diisocyanate, preferably by a process according to one of claims 1 to 13.

Images