Process for phosgene production with reuse of carbon dioxide from recycling of useful material

Abstract

The invention relates to a process for producing phosgene, especially for the reaction of phosgene with organic amino compound to give organic isocyanate. In this process, at least one carbon dioxide gas stream that has been formed from a hydrolysis of organically modified carbamate and may have been freed of secondary constituents is reductively converted to carbon monoxide. The resulting carbon monoxide is reacted with chlorine in a phosgene synthesis to give phosgene. The organically modified carbamate for the process can preferably be obtained from a chemolysis of end-of-life polyurethane material, especially with alcohols, amines or amino alcohols as chemolysis reagent.

Description

[0001] “Process for phosgene production with recycling of carbon dioxide from material recycling”

[0002] The invention relates to a process for the production of phosgene, in particular for the reaction of phosgene with organic amino compound to form organic isocyanate, wherein at least one carbon dioxide gas stream formed from a hydrolysis of organic carbamate and optionally purified from secondary components is converted to carbon monoxide, and the resulting carbon monoxide is converted to phosgene with chlorine in a phosgene synthesis.

[0003] The return of carbon dioxide (hereinafter also referred to as CO2) to the recycling chain represents a contribution to sustainability. In the past, there have been some efforts to utilize CO2, for example, for the production of carbon monoxide (hereinafter also referred to as CO).

[0004] EP 3 744 812 B1 describes how CO2 produced during the pyrolysis of polyurethane material and CO2 produced during the combustion of polyurethane material are converted to CO2 in a CO2 electrolysis process, reducing the CO2. The resulting CO2 is reacted with chlorine to form phosgene, which is used in the production of organic isocyanates, a building block of polyurethane. In particular, the CO2 produced during combustion must undergo a complex purification process before it can be used in electrochemical CO2 reduction.

[0005] The CO2 recycling process for the production of isocyanate compounds according to WO 2021 / 089737 A1 involves converting CO2 from an external source, such as the combustion of polyurethane recyclables, with hydrogen in a reverse water gas shift reaction (RWGS reaction) to produce CO2. Here, too, the CO2 must be extensively purified before use in the RWGS reaction.

[0006] Another way to recycle CO2 into the production of isocyanate compounds is the process described in WO 2022 / 167387 A1. In this process, the CO2 produced in a steam reforming process, along with additional CO2 from another CO2 source, is recycled into the steam reforming process. Other CO2 sources include, for example, the CO2 generated during cement production or waste incineration. CO2 from these sources also requires extensive purification before use in the steam reforming process.

[0007] The object solved by this invention is to reduce the processing effort of state-of-the-art CO2 recycling processes in order to make them more economical and / or environmentally friendly. Overall, a sustainable process for the production and recycling of polyurethane material is to be provided.

[0008] The expert understands the “sustainability” of a process in application of the UN definition of sustainable development according to the Brundtland Report of the “World Commission on Environment and Development” that the implementation of the process in the present makes as little or no contribution as possible to ensuring that future generations of humanity can no longer satisfy their own needs, in particular needs with regard to the use of resources such as fossil fuels and in particular with regard to the protection of the habitat, such as the protection of the Earth’s atmosphere.

[0009] It was found that the CO2 formed during the hydrolysis of organically modified carbamate compounds (in particular the CO2 formed during the hydrolysis of an organically modified carbamate obtained from the chemolysis of polyurethane material) has a very high degree of purity and can be made available for the reductive conversion to CO with less use of economic and / or ecological resources.

[0010] A first subject of the invention is thus a process for the preparation of phosgene (in particular for the preparation of organic isocyanate) by at least the following steps

[0011] Production of a CO2 gas stream by at least the following steps:

[0012] Providing at least one organically modified carbamate;

[0013] Hydrolysis of the provided at least one organically modified carbamate, at least with formation of organic amino compound and CO2;

[0014] Separation of the CO2 formed to obtain at least one CO2 gas stream; preferably purification of the CO2 gas stream from secondary components (in particular from secondary components selected from at least one compound from the list formed from alcohols, polyethers, hydrocarbons, organic amines, water, sulfur compounds, dust, oxygen, and nitrogen) by means of at least one purification method selected from condensation, adsorption, catalytic gas purification, or gas scrubbing to obtain a purified carbon dioxide;

[0015] Reduction of CO2 of the at least one produced, optionally purified CO2 gas stream to carbon monoxide;

[0016] Synthesis of phosgene at least from the carbon monoxide and chlorine obtained by said reduction.

[0017] For example, it is known from the documents DE 197 19 084 A1, EP 0 031 538 A2, WO 2022 / 171586 A1 and WO 2022 / 128871 A1 that organic amines and polyols as chemical compounds can be obtained from the polyurethane material by chemolysis of the polyurethane material, which chemical compounds can be recycled for the production of polyurethane material.

[0018] One approach to the material recycling of polyurethane material is, for example, alcoholysis or glycolysis, in which the urethane group is reacted with alcohol or glycol by transesterification or transurethanization:

[0019] Furthermore, the urethane group can be reacted with an amine to form a ureylene group:

[0020] The particular suitability of CCh-containing exhaust gas from the hydrolysis of organically modified carbamates, or from the chemolysis process of polyurethane material, for recycling is nowhere described.

[0021] "Polyurethane material" within the meaning of the present invention are the polyaddition products (sometimes, although not entirely correctly, also referred to as polycondensation products) obtained by reacting polyfunctional isocyanates (= isocyanate component of polyurethane production) with polyols (= polyol component of polyurethane production). Polyurethane material generally contains other structures in addition to the basic polyurethane structure outlined above, for example, structures with urea bonds. The presence of such structures deviating from the pure basic polyurethane structure in addition to polyurethane structures does not exceed the scope of the present invention. Polyurethane material is, in particular, polyurethane resins obtained by reacting polyfunctional isocyanates with polyols in the presence of a blowing agent.

[0022] In the terminology of the present invention, the term isocyanates encompasses all isocyanates known to the person skilled in the art in connection with polyurethane chemistry, such as in particular tolylene diisocyanate (TDI; prepared from tolylenediamine, TDA), the di- and polyisocyanates of the diphenylmethane series (MDI; prepared from the di- and polyamines of the diphenylmethane series, MDA), 1,5-pentane diisocyanate (PDI; prepared from 1,5-pentanediamine, PDA), 1,6-hexamethylene diisocyanate (HDI; prepared from 1,6-hexamethylenediamine, HDA), isophorone diisocyanate (IPDI; prepared from isophoronediamine, IPDA) and xylylene diisocyanate (XDI; prepared from xylylenediamine, XDA). The expression “one isocyanate” naturally also includes embodiments in which two or more different isocyanates (e.g. mixtures of MDI and TDI) were used in the production of the polyurethane foam, unless something else is expressly stated, for example by the formulation “exactly one isocyanate”.The totality of all isocyanates used in the production of polyurethane foam is referred to as the isocyanate component (of the polyurethane foam). The isocyanate component comprises at least one isocyanate. Similarly, the totality of all polyols used in the production of polyurethane foam is referred to as the polyol component (of the polyurethane foam). The polyol component comprises at least one polyol.

[0023] In the terminology of the present invention, the term polyols encompasses all polyols known to those skilled in the art in connection with polyurethane chemistry, such as, in particular, polyether polyols, polyester polyols, polyetherester polyols, and polyethercarbonate polyols. The expression "a polyol," of course, also encompasses embodiments in which two or more different polyols were used in the production of the polyurethane foam. Therefore, if reference is made below, for example, to "a polyether polyol" (or "a polyester polyol," etc.), this terminology naturally also encompasses embodiments in which two or more different polyether polyols (or two or more different polyester polyols, etc.) were used in the production of the polyurethane material.

[0024] In the terminology of the present invention, "organically modified carbamate" refers to organic urethane compounds. This includes both polyurethane material and, preferably, those organically modified carbamates formed during the chemolysis of polyurethane material by reaction with a chemolysis reagent.

[0025] An "organic compound" contains at least one covalent carbon-hydrogen bond in its molecule. An organic amino compound is therefore an organic substance that, as a chemical compound, contains at least one amino group and, in addition, at least one covalent carbon-hydrogen bond in its molecule. An organically modified carbamate is defined mutatis mutandis.

[0026] According to the invention, "chemolysis" refers to the chemical conversion of polyurethane material by cleavage of the polyurethane polymer structure through transesterification (also referred to as transurethanization) or through the formation of a ureylene group (also known as a carbonyldiimino group, *-NH-C(=O)-NH-*). A "chemolysis reagent" is a reagent that enters into a chemical reaction with the urethane bond, the reactive group of the polyurethane material, to carry out chemolysis.

[0027] In a preferred embodiment of the process, the organically modified carbamate is provided by chemolysis of polyurethane material. For the provision of the organically modified carbamate, it is sufficient within the scope of this embodiment if the organically modified carbamate is a direct process product of chemolysis of polyurethane material. This means that, for the step of providing the organically modified carbamate, it is sufficient to simply remove said organically modified carbamate as a raw material from a storage container or a feed line as part of a delivery.In this case, the phosgene producer, as the executor of the process according to the invention, does not carry out the chemolysis of the polyurethane material to produce the organically modified carbamate itself, but merely ensures that the organically modified carbamate provided has been produced by a supplier by chemolysis and is the supplier's process product. A preferred embodiment of the process is thus characterized in that at least one direct process product of a chemolysis of polyurethane material is used as the organically modified carbamate provided, comprising at least the following process steps:

[0028] Provision of polyurethane material;

[0029] Reaction of the provided polyurethane material with at least one chemolysis reagent (in particular selected from (a) a primary or secondary organic amine, (b) an amino alcohol having a primary or secondary amino group or (c) an alcohol having at least one hydroxyl group), to form at least one organically modified carbamate.

[0030] The polyurethane material provided can, in principle, be any type of polyurethane product, i.e., both polyurethane foams and polyurethane products from so-called CASE applications. Both flexible and rigid polyurethane foams are suitable, with flexible foams (e.g., from old mattresses, upholstered furniture, or car seats) being preferred. For polyurethane products from CASE applications, polyurethane elastomers, polyurethane adhesives, and polyurethane coatings are preferred. Of all polyurethane products, flexible polyurethane foams are particularly preferred. The polyurethane material provided is, for example, made from polyurethane waste from corresponding end-of-life polyurethane products (such as mattresses, upholstery, or insulation materials).

[0031] Furthermore, polyurethane material is preferred which, with regard to the isocyanate component, is based on an isocyanate selected from the group consisting of tolylene diisocyanate (TDI), the di- and polyisocyanates of the diphenylmethane series (MDI), 1,5-pentane diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and xylylene diisocyanate (XDI), and mixtures of two or more of the aforementioned isocyanates. Particular preference is given to polyurethane material which, with regard to the isocyanate component, is based on TDI or a mixture of TDI and MDI. Very particular preference is given to polyurethane material which, with regard to the isocyanate component, is based solely on TDI.

[0032] Furthermore, such polyurethane material is preferred which, with regard to the polyol component, is based on a polyol selected from the group consisting of a polyether polyol, a polyester polyol, a polyether ester polyol, a polyether carbonate polyol and a mixture of two or more of the aforementioned polyols.

[0033] Preferably, the preparation of the polyurethane material includes preparatory steps for the subsequent reaction with the chemolysis reagent. This involves, in particular, mechanical comminution of the polyurethane material. Such preparatory steps are known to those skilled in the art; reference is made, for example, to the review article by Simon, Borreguero, Lucas, and Rodriguez in Waste Management 2018, 76, 147-171.

[0034] It has proven particularly preferable if the provided polyurethane material has been subjected to inerting, at least comprising removing the gaseous oxygen surrounding the polyurethane material and / or embedded in its pores. Carrying out inerting is particularly recommended if the polyurethane material is in the form of a powder, granules or foam. By inerting the provided polyurethane material before reaction with the chemolysis reagent, a particularly high purity of the CCh gas stream obtained during hydrolysis is achieved. If, for example, a polyurethane material in the form of a foam is not inerted, the CO2 obtained during hydrolysis has an increased concentration of N2 and in particular of O2, which must be removed from the CO2 gas stream at great expense.

[0035] In a preferred embodiment, the inerting additionally comprises a step of supplying at least one inert gas to the polyurethane material (in particular nitrogen, carbon dioxide, argon or helium, most preferably carbon dioxide).

[0036] Inerting the provided polyurethane material is particularly preferably carried out by at least the following steps:

[0037] Degassing of the polyurethane material, wherein a first pressure of maximum 960 mbar (abs) and a temperature of maximum 120 °C are applied in a container, and the gas of the excess gas phase is removed via a gas removal device. To remove the gas, the first pressure in the container is preferably a negative pressure of less than 700 mbar ( a bs ), preferably a pressure of 0.1 mbar( a bs.) to 100 mbapabs ), and the gas is discharged via the gas discharge device.

[0038] After the gas has been removed, at least one inert gas (in particular nitrogen, carbon dioxide, argon or helium, most preferably carbon dioxide) is used to set a pressure of preferably a maximum of 1.8 bar ( a b s .), particularly preferably atmospheric pressure.

[0039] The degassing and the entire inerting process are described in the publication WO 2022 / 128871 A1, to which reference is expressly made in full here.

[0040] Likewise, within the scope of a further embodiment of the invention, it is possible for the aforementioned chemolysis reaction to be carried out as an integral step of the process for producing phosgene by the phosgene producer itself to provide the organically modified carbamate, and for the organically modified carbamate thus obtained to then be further subjected to hydrolysis to form CO2. Therefore, a corresponding preferred embodiment of the process is characterized in that said CO2 gas stream (31) is produced by chemolysis of polyurethane material, comprising at least the steps of providing polyurethane material;

[0041] Reacting the provided polyurethane material with at least one chemolysis reagent (in particular selected from (a) a primary or secondary organic amine, (b) an amino alcohol having a primary or secondary amino group or (c) an alcohol having at least one hydroxyl group), to form at least one organically modified carbamate;

[0042] Hydrolysis of the previously formed organically modified carbamate to form at least organic amino compound and CO2;

[0043] Separation of the CO2 formed while obtaining at least one CO2 gas stream.

[0044] Within the scope of the aforementioned embodiments of the invention, the hydrolysis step can be carried out as a separate process step from the conversion of the polyurethane material and / or simultaneously in one step. In a simultaneous sequence, a mixture containing the chemolysis reagent and additionally sufficient water is used.

[0045] In general, it is preferred if the organically modified carbamate provided is formed by reacting the provided polyurethane material with at least one chemolysis reagent under exclusion of oxygen or is a direct process product of such a reaction. This means that the reaction is carried out in an inert gas atmosphere (in particular in a nitrogen, carbon dioxide, argon, or helium atmosphere, particularly preferably a carbon dioxide atmosphere). Preferably, the chemolysis reagents used (water and chemolysis reagent) are also freed of oxygen by inert gas saturation. In this context, it is very particularly preferred if the provided polyurethane material is inertized as described above.

[0046] The provision of organically modified carbamate is achieved in a preferred embodiment by at least the following process steps:

[0047] Provision of polyurethane material;

[0048] Reacting the provided polyurethane material with at least one chemolysis reagent (in particular selected from (a) a primary or secondary organic amine, (b) an amino alcohol having a primary or secondary amino group or (c) an alcohol having at least one hydroxyl group), to form a composition containing at least one organically modified carbamate;

[0049] Mixing the previously obtained composition without prior separation of any water present in this composition with an organic solvent which is not completely miscible with the previously used chemolysis reagent, and phase separation into a carbamate phase (containing organically modified carbamate) and a solvent phase.

[0050] In this embodiment, the resulting carbamate phase is introduced into the hydrolysis step.

[0051] The aforementioned organic solvent to be used should not be completely miscible with the chemolysis reagent used in the chemolysis. This means that under the conditions prevailing for the above mixing, there must be a miscibility gap such that phase separation is possible. The organic solvent is particularly preferably selected from the group consisting of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and mixtures of two or more of the aforementioned organic solvents.

[0052] Within the scope of the integration of chemolysis as a process step in a further preferred embodiment of the phosgene production according to the invention, it is particularly preferred if the said conversion of polyurethane material to said organically modified carbamate and the said hydrolysis of the organically modified carbamate are carried out together in one process step.

[0053] In general, water for the hydrolysis and chemolysis reagent for the chemolytic conversion are preferably used in excess of stoichiometric amounts in the process according to the invention, regardless of whether the chemolytic conversion takes place alone or in one step in combination with the hydrolysis. This means that water for the hydrolysis is used in an amount that is theoretically sufficient to hydrolyze all polyurethane bonds of the provided polyurethane material, releasing at least carbon dioxide and organic amino compound. Similarly, the excess of stoichiometric use of chemolysis reagent means that it is used in an amount that is theoretically sufficient to convert all polyurethane bonds of the provided polyurethane material to form organically modified carbamates.When using the mass proportions of water and chemolysis reagent preferred according to the invention described below, both are regularly the case.

[0054] The chemolytic reaction is preferably carried out in such a way that the mass ratio of (total used) chemolysis reagent and (total used) water on the one hand to the provided polyurethane material on the other hand (i.e. [m(chemolysis reagent) + m(water)] / m(polyurethane product), m = mass) is in the range from 0.5 to 2.5, particularly preferably from 1.0 to 1.3, wherein the mass of water is 2.0% to 10% of the mass of the chemolysis reagent. The quantitative data with regard to water refer to the water added as a reagent for the hydrolysis. In comparison, any amounts of water already present from moisture in the chemolysis reagent used and / or in the polyurethane material used are small. Moisture in the chemolysis reagent used or in the polyurethane material used refers to traces of moisture such as can occur on an industrial scale.The mass of the water is more preferably 4.0% to 10.0%, particularly preferably 5.0% to 7.0%, of the mass of the chemolysis reagent used.

[0055] The chemolytic conversion and the hydrolysis can be carried out, for example, as chemolysis of the polyurethane material with a chemolysis reagent and water (preferably in the presence of a catalyst) at a temperature in the range of 130 °C to 220 °C, wherein the mass ratio of chemolysis reagent and water on the one hand to the polyurethane material on the other hand is in the range of 0.5 to 2.5 and the mass of water is 4.0% to 10% of the mass of the polyurethane material.

[0056] When combining chemolysis and hydrolysis in a single process step, it has proven particularly preferable not to add the water used for hydrolysis right at the beginning of the reaction period, or at least not to add it completely. It has proven useful to initially mix no or only a small proportion, namely 2% to 4%, of the total amount of water to be used with the remaining reactants (i.e., at least the chemolysis reagent and polyurethane material) and to add the remaining or entire amount of water later over the course of the reaction. The water for the hydrolysis of the organically modified carbamates formed as intermediates is added continuously or in portions at intervals in such a way that the boiling point of the reaction mixture always remains within the specified ranges, in particular within the particularly preferred range of 165°C to 185°C.The dosing time of the water is preferably in the range of 1.0 hour to 5.0 hours (depending on the boiling point of the chemolysis reagent used). In a preferred embodiment, a mass ratio of (total used) chemolysis reagent and (total used) water on the one hand to polyurethane material on the other hand [m(chemolysis reagent + water) / m(polyurethane material)] in the range of 1.1 to 1.3 is used. If the water is added gradually rather than all at once as described above, this applies to the total amount of water used.

[0057] The amount of water used in the joint implementation of chemolysis and hydrolysis in one process step is preferably 5.0% to 7.0% of the mass of the chemolysis reagent used; this applies particularly in conjunction with the aforementioned range of 1.0 to 1.3 for the mass ratio [m(chemolysis reagent + water) / m(polyurethane material)]. If the water is not added all at once, but gradually as described above, this applies to the total amount of water used in this step.

[0058] When chemolysis and hydrolysis are combined in a single process step, it is not necessary to add all the water at the beginning. In this case, the above-mentioned water quantity ranges relative to the mass of the chemolysis reagent refer to the total amount of water added by the end of the reaction. If the chemolysis reagent is added successively, the same applies.

[0059] In particular, it is also possible to use the polyurethane material

[0060] (I) initially adding only the chemolysis reagent or the chemolysis reagent and a first portion of water, and then (II) adding water or a second portion of water, in particular only after the polyurethane material has dissolved.

[0061] The expression "dissolved" in this context does not necessarily imply the presence of a "true" solution in the sense of a completely homogeneous mixture. It may well be that this is a cloudy "solution" of the polyurethane material; such a situation does not exceed the scope of the present invention.

[0062] When carrying out the joint implementation of the chemolysis and hydrolysis in the aforementioned steps (I) and (II), it is particularly preferred to add the water or the second portion of water continuously or in portions in step (II) such that the temperature of the liquid phase during step (II) deviates from the temperature of the liquid phase from step (I) by a maximum of 20 °C, preferably by a maximum of 15 °C, particularly preferably by a maximum of 10 °C, very particularly preferably by a maximum of 5.0 °C, and extraordinarily very particularly preferably by a maximum of 1.0 °C. In this way, the temperature is always high enough to ensure that the chemolytic conversion progresses.

[0063] A single-step chemolysis combined with hydrolysis is described, for example, in WO 2022 / 171586 A1, using an alcohol with at least one hydroxyl group as the chemolysis reagent. This publication is expressly incorporated herein by reference in its entirety.

[0064] A chemolysis procedure with hydrolysis as a separate step is described, for example, in US Pat. No. 4,336,406 and WO 2020 / 260387 A1, each using an alcohol with at least one hydroxyl group as the chemolysis reagent. This publication is expressly incorporated herein by reference in its entirety.

[0065] Chemolysis can generally be carried out, optionally in combination with hydrolysis, in any reactor known in the art for such a purpose. Stirred tank reactors and tubular reactors are particularly suitable as chemolysis reactors.

[0066] In a further embodiment, it is particularly preferred to support the chemolysis as a reaction of polyurethane material with a chemolysis reagent (for example, alone or in one step in combination with the hydrolysis) by using at least one catalyst. In this preferred embodiment, the catalyst used is particularly preferably at least one compound selected from carbonate, bicarbonate, orthophosphate, monohydrogen orthophosphate, metaphosphate, hydroxide, organic amine (especially diethanolamine), organometallic compounds (especially titanium tetrabutanolate, tin octanoate, or dibutyltin dilaurate), or mixtures of two or more of the aforementioned catalysts.Most preferably, at least one metal salt selected from a carbonate, a hydrogen carbonate, an orthophosphate, a mono-hydrogen orthophosphate, a metaphosphate or a mixture of two or more of the aforementioned metal salts is used as catalyst.

[0067] Orthophosphates are the salts of orthophosphoric acid, H3PO4, in which all protons have been removed (= PO4 3 ). Mono-hydrogen orthophosphates are the salts of orthophosphoric acid in which two protons have been split off (= HPO4 2 ). Metaphosphates are condensation products of orthophosphoric acid with the molecular formula [(PO3) ] n , where n denotes a natural number (in particular 3 or 4).

[0068] If a catalyst is used in a chemolysis step, it is preferably added in such an amount that its mass is 0.1% to 3.5% of the mass of the polyurethane material provided.

[0069] If a catalyst is used as an aqueous solution, the water used as solvent must also be taken into account in the above-mentioned quantitative data on the water used in the hydrolysis, ie the amount of water to be used additionally in the hydrolysis, if necessary, must be reduced accordingly.

[0070] It is further preferred to use at least one of the aforementioned catalysts for the hydrolysis.

[0071] In a further embodiment, it is particularly preferred to carry out the chemolysis (for example alone or preferably in one step in combination with the hydrolysis) as a reaction of polyurethane material with at least one chemolysis reagent selected from (a) a primary or secondary organic amine, (b) an amino alcohol having a primary or secondary amino group or (c) an alcohol having at least one hydroxyl group.

[0072] As an alcohol with at least one hydroxyl group, at least one alcohol with at least two hydroxyl groups is preferably suitable as a chemolysis reagent. It is particularly preferred if the chemolysis reagent is selected from ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl glycol, triethylene glycol, glycerol, 2-methyl-1,3-propanediol, or mixtures of two or more of the aforementioned alcohols.

[0073] As an amino alcohol with a primary or secondary amino group, at least one amino alcohol selected from ethanolamine, N-methylethanolamine, 3-amino-l-propanol is preferably suitable as a chemolysis reagent.

[0074] As a primary or secondary organic amine, at least one aliphatic primary or aliphatic secondary organic amine is preferably suitable as a chemolysis reagent. The primary or secondary amines are preferably mono- and / or diamines. 1,2-Ethylenediamine, 1,4-diaminobutane, 1,6-hexamethylenediamine, or a mixture of two or more thereof are particularly preferred chemolysis reagents as primary or secondary organic amines.

[0075] Said chemolytic conversion of polyurethane material with chemolysis reagent to form said organically modified carbamate is preferably carried out at a temperature in the range of 140°C to 220°C, preferably 170°C to 200°C. This temperature should also preferably be maintained during simultaneous conversion of polyurethane material with hydrolysis in one step. There are no particular requirements regarding the pressure. The reaction can be carried out at both reduced and elevated pressure; for example, at a pressure of 200 mbar (abs.) to 2000 mbar (abs.), preferably 500 mbar (abs.) to 1500 mbar (abs.), particularly preferably 900 mbar (abs.) to 1300 mbar (abs.), and in particular at ambient pressure. Pressures in the context of the present invention are always given as absolute pressures, indicated by a subscript "abs." following the pressure unit. (e.g. an absolute pressure of 900 mbar is expressed as “900 mbapabs.)"). According to a further embodiment, those processes are preferred in which the resulting CO2 gas stream has a temperature of 140 °C to 220 °C, preferably of 170 °C to 200 °C.

[0076] The resulting carbon dioxide can preferably be purified from secondary constituents, in particular nitrogen, oxygen, chemolysis reagent (such as diethylene glycol), sulfur compounds, dust, and water, using at least one purification method selected from condensation, adsorption, catalytic gas purification, or gas scrubbing to obtain a purified carbon dioxide (31a). However, the CO2 gas stream obtained by the process according to the invention has an excellent degree of purity for further use in the reduction of CO2. If appropriate, a few purification steps are required to process the CO2 prior to the reduction of CO2. These purification steps are easy and effective to carry out. The CO2 obtained from the hydrolysis of the CO2 gas stream contains, as its predominant secondary constituents, chemolysis reagent, as well as the organic amino compound and polyol formed during the chemolysis.These secondary components can be effectively removed by cleaning (4) the CO2 gas stream (31), in which at least the CO2 gas stream is passed through several condensers and cooled, whereby the organic and aqueous components contained in the gas stream as secondary components condense, are separated as a liquid and, after completion of the cleaning (4), a cleaned CO2 gas stream (31a) is fed to the reduction (6) to carbon monoxide.

[0077] A further improved purification of the CO2 gas stream is achieved when a combination of condensation and gas scrubbing is carried out.

[0078] The carbon monoxide required for the synthesis of phosgene is prepared by reducing (6) CO2 of the at least one optionally purified CO2 gas stream (31, 31a) prepared as described above to carbon monoxide (21a). In a further preferred embodiment of the process, the reduction of CO2 is carried out by at least one process selected from

[0079] A) the electrochemical reduction of CO2, preferably using electrical energy produced from renewable energy, B) a reformer process in which methane (preferably biomethane) and steam are converted into carbon monoxide with the addition of at least CO2 and with the addition of heat energy at a temperature of at least 500°C,

[0080] C) Conversion of hydrogen and CO2 to carbon monoxide in a reverse water-gas shift RWGS reaction zone.

[0081] 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.

[0082] When carrying out a reduction of CO2, it is preferred if the optionally purified CO2 gas stream for the reduction (6) is introduced into an electrolysis device and is reduced to carbon monoxide at an electrode, preferably at a gas diffusion electrode (particularly preferably using electrical energy produced from renewable energy).

[0083] For example, CCh electrolysis 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. The disadvantage of conventional high-temperature electrolysis is its poor scale-up capability, so low-temperature electrolysis is currently still preferable for larger CO quantities, e.g., more than 1 t / h of CO.

[0084] If CO2 electrolysis is operated as low-temperature electrolysis, the electrolysis takes place at a temperature below 150°C.

[0085] In all CO2 electrolysis processes, the CO2 gas is fed into the cathode chamber.

[0086] In the case of low-temperature electrolysis, CO2 is converted into carbon monoxide and optionally hydrogen, in particular at a gas diffusion electrode. At the same time, O2 or, if appropriate, alternatively, chlorine can be generated at the anode. If chlorine is generated at the anode, this chlorine can be fed into phosgene synthesis and thus into isocyanate production as an additional raw material. Those skilled in the art are familiar, for example, with electrodes and a method for carrying out the electrochemical reduction of CO2 from the publication WO 2021 / 069470 A. The electrochemical reduction of CO2 is preferably carried out according to a process of WO 2021 / 069470 A. This publication 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 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.

[0087] Following the established principles, a MEA (membrane electrode assembly) concept can also be used in 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 occur on both the anode and cathode sides. It is also possible to place a gas diffusion electrode in direct contact with the membrane.

[0088] The gas diffusion electrode used can be installed in the electrolysis cell in either a zero-gap or a finite-gap configuration. A preferred configuration for low-temperature electrolysis of CO2 is described in WO 2020 / 057998 A1, to which reference is expressly made in its entirety. An excess of CO2 can be supplied to the cathode compartment, or rather the gas diffusion electrode installed therein. Excess means introducing more CO2 than would be 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 compartment.

[0089] A suitable reformer process, in which methane (preferably biomethane) and steam are converted into carbon monoxide with the addition of at least said CO2 and with the addition of thermal energy at a temperature of at least 500°C, is described in PCT patent application number PCT / EP2022 / 052267, which is expressly incorporated by reference in its entirety. This process relates to the production of carbon monoxide from methane, steam, and CO2 for the preparation of phosgene for the synthesis of organic isocyanate, comprising at least the steps

[0090] Synthesis of carbon monoxide in a reformer process in which methane 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,

[0091] 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;

[0092] Providing CO2 for said addition to the aforementioned reforming process at least from said separation of CO2 from the aforementioned purification step, with the proviso that

[0093] 1) 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; or 2) for the provision of the CO2 added to the synthesis of the aforementioned reformer process, additional CO2 from another CCh source is used; or

[0094] 3) a combination of the above options 1) and 2) is chosen.

[0095] The preferred methane source for the reformer process is methane from biological sources. Experts define "methane from biological sources" (also referred to as biomethane), as distinct from fossil methane, as 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.

[0096] As a further CCh source for the above-mentioned step 2), preferably at least one external CCh source serves, which contributes CO2 which is not emitted by the process according to the invention. An external CO2 source would be, for example, the CO2 which arises during cement production, during FE production for ammonia synthesis, during the combustion of fuels (e.g. waste incineration), or CO2 which is obtained from the air. This CO2 from an external CCh source is obtained in a preferred embodiment of the process according to the invention by absorbing a CO2 portion from (i) process gases or exhaust gases which are selected from at least one process selected from cement production, ferrous metal production, combustion and / or (ii) from air by introducing it into alkali lye, for example potassium hydroxide solution. This forms potassium bicarbonate, which can then be thermally decomposed again to CO2 and potassium hydroxide solution.The CO2 released in this process is then fed into the reformer process for carbon monoxide synthesis. Such released CO2 can also be used for CO2 reduction according to A) (electrochemical reduction) or C) (RWGS reaction), independently of the reformer process.

[0097] In a particularly preferred embodiment of the process according to the invention, the carbon monoxide for the phosgene synthesis, in particular for the synthesis of phosgene, is produced from said CO2 by at least one conversion of hydrogen and CO2 in a reverse water-gas shift (RWGS) reaction zone to carbon monoxide. Such an embodiment is described, for example, in the document WO 2021 / 089737 A, to which reference is expressly made in its entirety. A very particularly preferred embodiment of the process according to the invention is characterized in that a hydrogen stream is provided and, together with the optionally purified CO2 gas stream, is converted according to the principle of the reverse water gas shift reaction (in particular in a reaction zone) to a product gas comprising carbon monoxide and optionally by-products.

[0098] 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 containing 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, together and reacted in the reaction zone.

[0099] In this particularly preferred process, at least the following steps are most preferably carried out for the production of carbon monoxide:

[0100] Feeding of provided hydrogen gas together with the said CO2 gas stream into an RWGS reaction zone and conversion of the reactants according to the principle of the RWGS reaction to form a product gas mixture of water vapor, CO and optionally by-products, in particular lower hydrocarbons, particularly preferably methane;

[0101] 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;

[0102] 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;

[0103] The remaining carbon monoxide from the separation is fed into the phosgene synthesis. The RWGS reaction is preferably carried out in the presence of at least one catalyst.

[0104] This is particularly preferably selected from at least one compound from the group:

[0105] (I) Mixed metal oxides of the formula A(i- w -x)AVA" x B(iyz)B'yB"zO3-deita where:

[0106] 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

[0107] 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

[0108] 0 ^ w ^ 0.5; 0 ^ x < 0.5; 0 ^ y ^ 0.5; 0 ^ z ^ 0.5 and - 1 V delta VI ;

[0109] (II) Mixed metal oxides of the formula A(iwx)A' w A" x Bi- y -z>B' y B"zO3-deita where:

[0110] 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

[0111] 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

[0112] 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

[0113] 0V w V 0.5; 0V x V 0.5; 0VyV 0.5; 0 V z V 0.5 and - 1 V delta V 1 ;

[0114] (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

[0115] M3 is selected from the group: Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu;

[0116] (IV) Mixed metal oxides of the formula LO x (M <y / z)Al(2-y / z)O3)z; wobei hier gilt:

[0117] 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

[0118] 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

[0119] 1 < x V 2; 0 < y V 12; and 4 V z V 9;

[0120] (V) Mixed metal oxides of the formula LO(AhO3)z; where:

[0121] 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

[0122] 4 V to V 9;

[0123] (VI) oxide catalyst comprising Ni and Ru.

[0124] (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:

[0125] 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

[0126] 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

[0127] 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.

[0128] In another embodiment, the hydrogen stream provided for the RWGS reaction is preferably obtained by electrolysis of water to hydrogen and oxygen. Water electrolysis to produce hydrogen gas represents the electrochemical conversion of water. Using electricity, water is split into hydrogen and oxygen. Known processes include proton exchange electrolysis (PEM electrolysis), which is described, for example, in EP 3489394 A. Another process is alkaline water electrolysis. The two processes differ, in particular, in the process parameters such as temperature, pressure, and pH. However, both processes lead to the target products of water and oxygen gas. Water electrolysis can be carried out using state-of-the-art systems. Technical systems for alkaline water electrolysis and PEM electrolysis are well known and commercially available.The principles of water electrolysis are described as examples in Chapter 6.3.4 in Volkmar M. Schmidt’s “Electrochemical Process Engineering” (2003 Wiley-VCH-Verlag; ISBN 3-527-29958-0).

[0129] It is particularly preferred if the water electrolysis (5) for providing the hydrogen stream is carried out using electrical power generated from renewable energy, in particular from renewable energy in the form of wind power, solar energy or hydropower.

[0130] The carbon monoxide obtained from the reduction of CO2 is purified, if necessary, from any byproducts present and used for the synthesis of phosgene. This synthesis of phosgene is carried out by reacting at least chlorine gas and carbon monoxide, with at least the carbon monoxide from the reduction of CO2 being converted and phosgene being extracted. The purification of the carbon monoxide preferably takes place before use in the synthesis of phosgene by at least the following steps:

[0131] Separation of water,

[0132] Separation of unreacted carbon dioxide from the gas mixture obtained from the separation of water, in particular by means of amine scrubbing and recycling of the unreacted carbon dioxide to the reduction of CO2 in the process according to the invention,

[0133] Separation of any hydrogen present from the gas mixture obtained after separation of unreacted carbon dioxide, in particular using a cold box.

[0134] In a further preferred embodiment of the process, the carbon dioxide is separated after water has been separated from the carbon monoxide-containing product gas. For this purpose, the carbon monoxide-containing gas is first fed to a water separation unit, where the water is separated. 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 carbon monoxide-containing gas is cooled to separate the water, for example, and the water is separated, for example as condensate.

[0135] “Amine scrubbing” here refers in particular to the generally known scrubbing 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 even at relatively low pressure in an absorption column.

[0136] A preferred variant of the process according to the invention is a process in which the carbon monoxide-containing gas (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 which, at 25°C and 1013 mbar, contains at least 95 vol.% carbon monoxide, more preferably at least 99 vol.% carbon monoxide. The product gas introduced is preferably first separated into two gas streams in the H2-CO separation unit. This produces one gas in the form of a gas stream which contains at least 95 vol.% (preferably at least 99 wt.%) carbon monoxide, and another gas in the form of a gas stream whose largest constituent is hydrogen and which contains, among other things, carbon monoxide and methane. The additional 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.An 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 subjected to subsequent residual gas treatment to concentrate the hydrogen. After processing through the residual gas treatment, a hydrogen-enriched gas is obtained in the form of a gas stream, and another gas – the so-called residual gas from the residual gas treatment or tail gas – is obtained in the form of a gas stream. This gas contains a mixture of CO, methane, and a smaller amount of hydrogen than the hydrogen-enriched gas.

[0137] 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 electrical current generated from renewable energy, in particular from renewable energy in the form of wind power, solar energy, or hydropower. - TI -.

[0138] In a particularly preferred embodiment of the process, the phosgene formed by the phosgene synthesis is used in a further step for the production of organic isocyanate, in which the phosgene from the phosgene synthesis is reacted with at least one organic amino compound, in particular with the organic amino compound obtained during the hydrolysis of the organically modified carbamate, and at least organic isocyanate is extracted. Preferably, at least organic isocyanate and hydrogen chloride are extracted.

[0139] In general, those processes according to the invention of this embodiment are preferred in which the obtained organic isocyanate contains at least two isocyanate groups. For this purpose, the organic amino compound having at least two amino groups, in particular the organic amino compound obtained during the hydrolysis of the organically modified carbamate, is preferably used as the reactant in the synthesis.

[0140] Particularly preferably, the organic isocyanate obtained contains at least two isocyanate groups and has a molecular weight of at most 1000 g / mol, in particular of at most 800 g / mol.

[0141] Organic amines which are very particularly preferably used are selected from tolylenediamine (IDA), methylenedi(phenylamine) (MDA) (in turn preferably selected from diphenylmethane-2,2'-diamine, diphenylmethane-2,4'-diamine, diphenylmethane-4,4'-diamine or mixtures thereof), hexamethylenediamine, isophoronediamine, 1,3-bis(aminomethyl)benzene, cyclohexyldiamine or mixtures thereof, where TDA, MDA or mixtures thereof, in particular the TDA or MDA obtained in the hydrolysis of the organically modified carbamate, are very particularly preferred organic isocyanates.

[0142] Very particularly preferably obtained organic isocyanates are selected from tolylene diisocyanate (TDI), methylene di(phenyl isocyanate) (MDI) (in turn preferably selected from diphenylmethane 2,2'-diisocyanate, diphenylmethane 2,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate or mixtures thereof), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)benzene (XDI), cyclohexyl diisocyanate (CHDI) or mixtures thereof, with TDI, MDI or mixtures thereof being very particularly preferred organic isocyanates. Furthermore, in the embodiment involving the synthesis of organic isocyanate, hydrogen chloride is preferably also produced in addition to said organic isocyanate. It is again preferable to supply this hydrogen chloride as a starting material for the production of chlorine for said synthesis of phosgene.The necessary separation and purification of the hydrogen chloride formed in the isocyanate production can then be carried out by an oxidative conversion in a thermocatalytic gas phase oxidation with oxygen to chlorine and water and, if necessary, using O2 from water electrolysis.

[0143] Another alternative approach to utilizing hydrogen chloride as a starting material for chlorine production is the reaction of hydrogen chloride with water to form hydrochloric acid, followed by electrochemical oxidation of the hydrochloric acid to chlorine and, if necessary, hydrogen. This aqueous hydrochloric acid is used, in particular, for the previously described electrochemical oxidation following hydrochloric acid electrolysis with a gas diffusion electrode, the electrochemical oxidation following hydrochloric acid diaphragm electrolysis, or the electrochemical oxidation following chlor-alkali electrolysis. In the case of hydrochloric acid electrolysis with a gas diffusion electrode, the O2 required can be obtained from water electrolysis.

[0144] The hydrogen chloride produced during isocyanate production can also be converted into hydrochloric acid after purification and absorption in water, and the resulting hydrochloric acid can be sold on the market for various applications.

[0145] Within the scope of a particularly preferred embodiment of the process, a phosgene synthesis is additionally carried out by reacting at least chlorine gas and the carbon monoxide previously obtained after purifying the said carbon monoxide-containing product gas from step c); an isocyanate production by reacting the obtained phosgene with at least one organic amine to form at least one organic isocyanate compound and hydrogen chloride; a separation and purification of the hydrogen chloride formed in the isocyanate production and a subsequent oxidative conversion of the hydrogen chloride, selected from a conversion of hydrogen chloride in a thermocatalytic gas phase oxidation with oxygen to chlorine and water, optionally using oxygen from water electrolysis, a conversion of hydrogen chloride with water to hydrochloric acid and subsequent electrochemical oxidation of the hydrochloric acid to chlorine and optionally hydrogen;a subsequent addition of the chlorine formed to the said synthesis of phosgene following the oxidative conversion of the hydrogen chloride, optionally with the addition of an additional quantity of chlorine to the said synthesis of phosgene originating from a chlor-alkali electrolysis;

[0146] The organic isocyanates obtained can optionally be reacted in an additional step of the process with at least one organic compound having at least two hydroxyl groups, in particular at least one polyester polyol or polyether polyol, to form polyurethane material.

[0147] Polyurethane materials produced in this way are components of commercial products, for example, in the form of foams, paints, and insulating compounds. At the end of their life cycle, they can be reused as polyurethane material for the process according to the invention.

[0148] Another object of the invention is the use of CO2, which is the direct product of a process comprising at least the step of hydrolyzing at least one organically modified carbamate, in a reduction reaction (ie a reduction of CO2) for producing carbon monoxide for phosgene production.

[0149] Corresponding embodiments of the process according to the invention also apply mutatis mutandis to this subject matter of the invention. Yet another subject matter of the invention is the use of carbon monoxide, the direct product of a process comprising at least one reduction reaction of CO2, which was produced by hydrolysis of at least one organic compound selected from organically modified carbamate, for the production of phosgene.

[0150] Corresponding embodiments of the method according to the invention also apply mutatis mutandis to this subject matter of the invention.

[0151] Yet another object of the invention is an apparatus for producing phosgene, comprising at least one unit for providing a CO2 gas stream which is a direct product of a process which comprises at least the step of hydrolyzing at least one organic compound selected from organically modified carbamate, said unit comprising at least one CCE outlet for said CO2 gas stream;and optionally at least one unit for purifying the CO2 gas stream of secondary components containing at least one unit from the group formed by condensation unit, adsorption unit, gas scrubbing unit or catalytic gas purification unit, wherein the unit for purifying the CO2 gas stream has at least one inlet for the CO2 gas stream as the CO2 gas stream to be purified, which inlet is in fluid communication with the CCh outlet of the unit for providing the CO2 gas stream and wherein the unit for purifying the CO2 gas stream has at least one outlet for a purified CO2 gas stream;and at least one unit for reducing the at least one provided, optionally purified, CO2 gas stream to carbon monoxide, comprising at least one inlet for the CO2 gas stream, which is in fluid communication with at least one outlet of the unit for providing a CO2 gas stream, optionally via the at least one unit for purifying the CO2 gas stream, and comprising at least one outlet for carbon monoxide; at least one unit for producing phosgene, comprising at least one inlet for chlorine gas, which is in fluid communication with a source of chlorine gas, and at least one inlet for carbon monoxide, which is in fluid communication with at least one outlet for carbon monoxide of the unit for reducing said CO2 gas stream; at least one outlet for phosgene.;

[0152] A fluid connection is a device that connects device parts to one another and through which a substance, which can exist in any state of matter, can be transported as a material flow from one device part to the next, for example, a supply line in the form of a pipe. The term "fluidly connected" means that the named device parts are connected to one another via a fluid connection.

[0153] A "reaction space" is a volume of a device in which the reactants involved in a chemical reaction are present together and in which the chemical reaction takes place. For a chemical reaction, this could, for example, be the volume of a vessel or container in which the reactants are present together and are to be reacted.

[0154] A preferred embodiment of the device is suitable for the simultaneous execution of the chemolytic conversion and the hydrolysis in one step and is characterized in that the unit for providing a CO2 gas stream contains a unit for the hydrolysis of at least one organic compound, comprising at least one hydrolysis device containing at least one inlet for a chemolysis reagent, at least one inlet for water-containing liquid, at least one inlet for polyurethane material and at least one outlet for the CO2 gas stream, wherein said organic substance and said liquid can be contacted in a reaction zone of the hydrolysis device and the CO2 gas stream formed can be discharged through said outlet. A further preferred embodiment of the device is suitable for the separate execution of the chemolytic conversion and the hydrolysis and is characterized in thatthat the unit for providing a CO2 gas stream contains a unit for hydrolyzing at least one organic compound, comprising at least one chemolysis device containing at least one inlet for a liquid containing a chemolysis reagent, at least one inlet for polyurethane material, and at least one outlet for organically modified carbamate, wherein said organic substance and said liquid are contacted in the reaction zone of the reactor and can be converted to at least one organic compound selected from organically modified carbamate; and at least one hydrolysis device containing at least one inlet for a water-containing liquid, at least one inlet for organically modified carbamate, and at least one outlet for the CO2 gas stream,wherein in a reaction zone of the hydrolysis device, said organically modified carbamate and said aqueous liquid can be contacted and the CO2 gas stream formed can be discharged through said outlet, wherein the inlet for organically modified carbamate is in fluid communication with the outlet for organically modified carbamate of the reactor for chemolysis.

[0155] It is further preferred within the scope of this embodiment if the unit for the hydrolysis of at least one organic compound additionally contains at least one separation device, wherein the outlet for organically modified carbamate of the chemolysis device is in fluid communication with the inlet of the separation device and the separation device has at least one inlet for organic solvent which is not completely miscible with the previously used chemolysis reagent, which inlet is in fluid communication with a source of said organic solvent and contains at least one outlet for a carbamate phase, which in fluid communication with the inlet of the hydrolysis device.The separation device is designed such that the composition obtained during the chemolysis, at least comprising at least one organically modified carbamate, can be contacted with an organic solvent that is not completely miscible with the previously used chemolysis reagent. After thorough mixing and contacting, a phase separation into a carbamate phase (containing organically modified carbamate) and a solvent phase can be effected, from which the carbamate phase can be separated and discharged from the separation device. In this embodiment, the carbamate phase is introduced into the hydrolysis device.

[0156] In a further preferred embodiment of the device, the unit for reducing the at least one provided, optionally purified, CO2 gas stream (31, 31a) is an electrolysis unit with a gas diffusion electrode for CO2 reduction or a reverse water gas shift reactor.

[0157] The invention is explained in more detail below with reference to Figures 1 and 2, using examples 1 to 4, without limiting the invention to these examples. In Figures 1 and 2, the following reference numerals have the meanings shown on the right:

[0158] 1 Chemolysis, here: Glycolysis la Gas stream CO2 from chemolysis (glycolysis)

[0159] 1b Chemolysis reagent (here: diethylene glycol (DEG)) additive to replace losses

[0160] 1c Polyol from chemolysis

[0161] Id Gas stream CO2 from coupled chemolysis with hydrolysis (here: hydroglycolysis) le H2O + catalyst Na2COs for coupled chemolysis and hydrolysis (here: hydroglycolysis)

[0162] 2 Hydrolysis

[0163] 2a Gas stream CO2 from hydrolysis

[0164] 2b TDA from hydrolysis

[0165] 2c H2O for hydrolysis

[0166] 3 coupled chemolysis with hydrolysis (here: hydroglycolysis)

[0167] 3a Polyol solvent from hydroglycolysis

[0168] 4 Solvent Extraction

[0169] 4a organic amino compound (here: TDA) / organically modified carbamates from solvent extraction

[0170] 4b H2O replacement losses

[0171] 4c polyol toluene from solvent extraction

[0172] 4d Polyol and solvent from Solvent Extraction 5 Solvent Evaporation

[0173] 5a Toluene from solvent evaporation

[0174] 5b Solvent cyclohexane from 5

[0175] 5 c Solvent compensation for losses

[0176] 5d polyol

[0177] 6 Polyol production

[0178] 6a Polyol from polyol production

[0179] 6b Rejection of residues

[0180] 7 Amine cleaning

[0181] 7a organic amino compound (here aTDA) from amine purification

[0182] 7b Chemolysis reagent (here DEG) from amine purification

[0183] 7 c remainder

[0184] 7d H2O from amine purification

[0185] 7f H2O from Amine Purification

[0186] 8 Isocyanate production

[0187] 8a TDI

[0188] 8b HCl from isocyanate production

[0189] 9 Phosgene production

[0190] 9a Phosgen

[0191] 10 HCl Recycling

[0192] 10a Chlorine from HCl recycling

[0193] 11 PU foam production

[0194] 15 Process gas treatment CO by: cooling, drying, CO2 separation (amine scrubbing) &

[0195] H2-CO separation

[0196] 15a H2 from H2-CO separation

[0197] 15b CO from H2-CO separation

[0198] 15c CO2 from CO2 capture

[0199] 20 H2 production

[0200] 20a H2 from water electrolysis

[0201] 20c H2O for water electrolysis replacement losses

[0202] 30 CO production by reduction of CO2 (CO2 electrolysis or RWGS) 30a CO product gas stream from the reduction of CO2

[0203] 40 CO2 compression

[0204] 40a CO2 after compression

[0205] 41 CO2 upgrading (CO2 from chemolysis)

[0206] 41a CO2 from chemolysis after treatment

[0207] 41b CO2 Purge Electricity from 41

[0208] 41c CO2 Purge electricity from 44

[0209] 44 CO2 upgrading from hydrolysis

[0210] 44a CO2 purified from hydrolysis

[0211] 45 CO2 upgrading hydroglycolysis

[0212] 45a CO2 purified from hydroglycolysis treatment

[0213] 45b CO2 purge from treatment 45

[0214] 46 CO2 storage (optional)

[0215] 52 Production of polyurethane material (here: PU foam production)

[0216] 52a Polyurethane material for the market

[0217] 54 Market / Recycling Collection / Separation

[0218] 54a Recycled PU foam

[0219] 60 Provision of polyurethane material (here: PU foam preparation & inerting)

[0220] 60a Polyurethane material (here: TDI-based PU foam)

[0221] 70 Heating RWGS electric or BioGas or H2

[0222] Examples

[0223] Example 1 (Fig, 1):

[0224] A schematic overview of the overall process for the production of low-emission toluene diisocyanate (TDI), CO production using RWGS, which is heated with bio-natural gas, HCl recycling using CH production by thermocatalytic gas phase oxidation (Deacon) of HCl and H2 provision from water electrolysis and CO2 provision from chemolysis of polyurethane material (TDI based foams) with diethylene glycol (DEG) as chemolysis reagent and hydrolysis of the resulting organically modified carbamates in a separate step.

[0225] 300 kg of a polyurethane material 60a in the form of a residual moisture-containing polyurethane foam with a weight fraction of 33 wt.% TDI and 67 wt.% polyol (ARCOL® Polyol 1108) are provided. This material is dissolved with 300 kg of diethylene glycol as the chemolysis reagent and with the addition of 5.5 kg of Na2CO3 as the catalyst in a chemolysis 1 under a carbon dioxide inert gas atmosphere. The product mixture obtained during the dissolution, comprising 227.1 kg of polyol, 251.1 kg of diethylene glycol, and 119.6 g of TDA / organically modified carbamates, is added to a solvent extraction 4 with toluene as the solvent prior to hydrolysis 2. This solvent extraction is carried out analogously to the example from WO 2020 / 260387 A1. The solvent phase obtained after phase separation with 1367 kg toluene and 227.1 kg polyol is transferred to a solvent evaporation 5, where the solvent toluene is almost completely separated from the polyol and returned to the solvent extraction 4.The resulting polyol is further processed in polyol production 6.

[0226] The carbamate phase obtained after phase separation in solvent extraction 4, containing 119.6 kg of TDA / organically modified carbamate, is transferred to hydrolysis 2, where it is hydrolyzed in a carbon dioxide inert gas atmosphere with the addition of a total of 16.5 kg of water for 2.5 h at 180°C. This yields a total liquid composition containing 51.1 kg of TDA and 300 kg of diethylene glycol, as well as a CO2 gas stream 2a. The liquid composition is transferred to an amine purification 7, where it is separated into 47.92 kg of TDA 7a and approximately 300 kg of diethylene glycol 7b, and residue 7c.

[0227] A gas stream 1a containing 3.7 kg / h of CO2, containing traces of N2 and O2, DEG, and water, is withdrawn from chemolysis 1 and fed to CCE treatment 41. The gas stream 1a has a temperature of 180°C and a pressure of 1.01 bpabs. The gas stream 1a is cooled to 25°C by means of a heat exchanger, thereby largely removing water and DEG.

[0228] Subsequently, the gas stream 1a is dried via zeolite, a partial stream 41a is purged with 0.3 kg CO2 and the residual gas stream 41a with 3.4 kg CO2 is fed to the compression 40 at 25°C.

[0229] A CO2 gas stream 2a containing 33.2 kg / h of CO2 and traces of N2 and O2, DEG, water, and toluene is taken from hydrolysis 2. The gas stream has a temperature of 180°C and a pressure of 1.01 bar abs. Gas stream 2a is cooled to 25°C using a heat exchanger, largely removing water and DEG.

[0230] The cooled gas stream is then dried via zeolite, a partial stream is purged with 2 kg / h CO2 and the residual gas stream 44a with 31.2 kg / h CO2 is fed to the compression 40 at 25°C.

[0231] A continuous gas stream 40a with 34.6 kg / h CO2 at 30 bar and 40°C is taken from the compressor stage 40 and fed to a CO production by reduction of CO2 30 in the form of a RWGS in the reaction chamber of the RWGS.

[0232] The RWGS reaction is operated at 802°C, with biogas being fed in and burned to maintain the reaction temperature. Optionally, hydrogen could also be used for heating or electrically heated. 34.6 kg / h of CO2 and 1.57 kg / h of hydrogen 20a from water electrolysis 20 are fed into the RWGS reaction chamber for CO production by reducing CO2 30, which operates at a temperature of 802°C and 30 bar.

[0233] From the RWGS reaction, the resulting product gas mixture 30a consisting of CO, H2O, unreacted CO2 and unreacted H2 as well as by-products, mainly small amounts of methane, is removed and cooled in a process gas cooling system of the process gas conditioning CO 15.

[0234] The gas mixture is then fed into a process gas dryer for the CO 15 process gas treatment system, where a total of approximately 14.1 kg / h of water is separated. This water is then fed into the water electrolysis unit 20.

[0235] A total of 1.57 kg / h of hydrogen is extracted from water electrolysis 20, and 14.13 kg / h of water is fed into the water electrolysis. This water consists of the recycled water from the process gas drying and freshly added water.

[0236] The remaining gas mixture from the process gas drying is fed to a CO2 separation in the process gas treatment CO 15. The CO2 separation takes place by means of amine scrubbing, whereby the separated CO2 15c is fed back into the reduction of CO2 30 (RWGS reaction). The energy for the CO2 separation from the formed CCh-amine complex is obtained from the above-mentioned process gas cooling, in which the RWGS reaction gases are cooled. The gas freed from CO2 is fed to the H2-CO separation in the process gas treatment CO 15. For the H2-CO separation, a so-called cold box is used, in which the H2-CO gas mixture is cooled and hydrogen and CO are separated. The separated hydrogen (15a) is fed back into the RWGS reaction (31). 22.0 kg / h of CO 15b from the H2-CO separation are fed into a phosgene synthesis 9. The CO 15b reacted with 55.78 kg / h of chlorine 10a, which was taken from an HCl recycling process 10.The HCl gas is converted to chlorine by thermocatalytic gas-phase oxidation (Deacon) of HCl from isocyanate production 8. Optionally, the O2 from water electrolysis 20 can be used for the oxidation of HCl gas in the Deacon process 10.

[0237] From the phosgene synthesis 9, 77.78 kg / h of phosgene are taken and reacted in an isocyanate production 8 with 47.92 kg / h of toluene diamine 7a to form 68.35 kg / h of toluene diisocyanate 8a.

[0238] The resulting HCl gas, at a rate of 57.35 kg / h, is purified via low-temperature distillation and fed into a CH production process by thermocatalytic gas-phase oxidation 10. In the thermocatalytic gas-phase oxidation 10, the HCl gas is converted to chlorine and H2O with oxygen at approximately 300°C over a ruthenium oxide-based catalyst. The required oxygen of 12.57 kg / h is taken from the water electrolysis 20.

[0239] The resulting toluene diisocyanate 68.35 kg / h 8a is reacted with the 227.1 kg / h polyol (essentially corresponding to the specification of ARCOL® Polyol 1108) 6a obtained from the process to produce 295.44 kg / h polyurethane material in a PU foam production 52.

[0240] After use of the polyurethane material in various applications on the market 54, it can be collected and recycled in order to provide the resulting polyurethane material as a valuable material after processing and preparation 60 of chemolysis (1).

[0241] The hydrogen 20a is produced in a water electrolysis plant 20 with a capacity of 0.088 MW, using renewable energy. The water electrolysis plant 20 is an alkaline water electrolysis plant operating at a current density of 8 kA / m 2and a cell voltage of 2 V per electrolysis element. 0.088 MW and 14.13 kg / h of water (16a+20c) are supplied from the process gas cooling system, the process gas drying system, and from the CO 15 separation process gas treatment system, as well as externally. 1.57 kg / h of H2 and 12.56 kg / h of oxygen are extracted from the water electrolysis system.

[0242] The process according to the invention recycles almost all raw materials of the TDI-based PU material, such as the amine and the polyol, thus closing the value chain.

[0243] By using renewable energy in water electrolysis, the CO2 footprint of the phosgene produced from CO and CH is further reduced, thus enabling a more sustainably produced TDI and the resulting PU material.

[0244] Example 2 (Fig 1):

[0245] This example corresponds to Example 1 except for the implementation of CO2 reduction.

[0246] A low-temperature CO2 electrolysis is used to reduce CO2 30. The CO2 electrolysis is conveniently carried out according to European patent application number 18195279.7, Example 1. The electrolysis is carried out at a pressure of 1.2 bar abs. Ten elements of 1.6 m each are used. 2 Electrode area is used, which are connected together to form an electrolyzer. The electrolysis is carried out at a cell voltage of 3.7 V, a current density of 4.05 kA / m 2 It operates with a CO2 efficiency of 65%. It consumes 0.239 MWh of renewable energy, primarily wind power, corresponding to a connected load of 0.239 MW.

[0247] 34.6 kg / h of CO2 are fed to the CO2 electrolysis unit 30 after drying, purification in 41, and compression 40 at a pressure of 1.2 bar abs. A gas mixture 30a of 22 kg / h CO, 200 kg / h CO2, and 0.85 kg / h H2 is withdrawn from the CO2 electrolysis unit 30.

[0248] Furthermore, 19.36 kg / h of O2 are withdrawn from the anode chamber of the electrolysis.

[0249] The gas mixture 30a produced from electrolysis 30 is fed to a process gas treatment 15 with drying and CO2 separation in the form of an amine scrubbing, and the unreacted CO2 15c is separated from the mixture and returned to electrolysis 30. The gas freed from CO2, consisting of CO and H2, is fed to a CO-H2 separation in the form of a cold box, in which the separation of CO and H2 takes place. 22 kg / h of CO 15b is reacted with the CH 10a originating from HCl recycling 10 to form phosgene 9a in phosgene production 9, and this is reacted with the TDA 7a originating from hydrolysis 2 and amine purification 7 to form TDI 8a in isocyanate production 8.

[0250] Example 3 (Fig 2):

[0251] Fig. 2 A schematic overview of the overall process for the production of low-emission toluene diisocyanate (TDI), with rWGS reaction, chlorine production, PU production, use and recycling of the polyurethane material waste and recycling via hydroglycolysis and use of CO2 for the RWGS reaction

[0252] 300 kg of a polyurethane material 60a in the form of a residual moisture-containing polyurethane foam with a weight fraction of 33 wt.% TDI and 67 wt.% polyol (ARCOL® Polyol 1108) are provided. This is reacted with 300 kg of diethylene glycol as the chemolysis reagent and with the addition of 5.5 kg of Na2CO3 as the catalyst in a combined chemolysis and hydrolysis (here: hydroglycolysis) 3 with a total of 16.5 kg of water under a carbon dioxide inert gas atmosphere as described in Example x of publication WO XXX. A product solution 3a and a CO2 gas stream ld are obtained.

[0253] After the reaction, the product solution is transferred to a solvent extraction stage 4 and mixed with 1866 kg of cyclohexane. The solvent phase 4d obtained after phase separation, comprising 1866 kg of cyclohexane, 223.6 kg of polyol, and 1.8 kg of residue, is transferred to a solvent evaporation stage 5, where the solvent cyclohexane is almost completely separated from the polyol and returned to the solvent extraction stage 4. The resulting polyol is further processed in the polyol production stage 6 and separated from the residues 6b.

[0254] The amine-containing phase (TDA) obtained after phase separation in solvent extraction 4, containing 52 kg TDA, water, salts and 300 kg DEG, is transferred to an amine purification 7 and separated there into 47.92 kg TDA 7a and approximately 300 kg diethylene glycol 7b and residue 7c.

[0255] A gas stream ld containing 37.4 kg / h of CO2, containing traces of N2 and O2, DEG, and water, is withdrawn from hydroglycolysis 3 and fed to CO2 treatment 45. The gas stream ld has a temperature of 180°C and a pressure of 1.01 bar abs. The gas stream ld is cooled to 25°C using a heat exchanger, thereby largely removing water and DEG. Subsequently, the gas stream ld is dried using zeolite, a partial stream 45b is purged with 2.8 kg of CO2, and the residual gas stream 45a containing 34.6 kg / h of CO2 is fed to compression 40 at 25°C.

[0256] A continuous gas stream 40a with 34.6 kg / h CO2 at 30 bar and 40°C is taken from the compressor stage 40 and fed to a CO production by reduction of CO2 30 in the form of a RWGS in the reaction chamber of the RWGS.

[0257] The RWGS reaction 30 operates at 802°C, with biomethane being fed in and burned to maintain the reaction temperature. Optionally, hydrogen could also be used for heating or electrical heating. 34.6 kg / h of CO2 40a and 1.57 kg / h of hydrogen 20a from a water electrolysis 20 are fed into the reaction chamber of the RWGS 30, which operates at a temperature of 802°C and 30 bar.

[0258] From the RWGS reaction, the resulting product gas mixture 30a consisting of CO, H2O, unreacted CO2 and unreacted H2 as well as by-products, mainly small amounts of methane, is removed and cooled in a process gas cooling system of the process gas conditioning system 15.

[0259] The gas mixture is then fed to a process gas dryer (process gas treatment 15), where a total of approximately 14.1 kg / h of water is separated. This water is then fed to the water electrolysis plant 20.

[0260] A total of 1.57 kg / h of hydrogen 20a is withdrawn from water electrolysis 20, and 14.13 kg / h of water is fed into the water electrolysis. This water consists of the recycled water from the aforementioned process gas drying and freshly added water.

[0261] The remaining gas mixture from the process gas drying is fed to a CO2 separation process gas treatment 15. CO2 separation is carried out by amine scrubbing, with the separated CO2 15c being fed back to the RWGS reaction 30.

[0262] The energy for CO2 separation from the formed CCh-amine complex is obtained from the process gas cooling of the process gas treatment 15, in which the RWGS reaction gases 30a are cooled. The gas freed from CO2 is fed to the H2-CO separation of the process gas treatment 15. For the H2-CO separation, a so-called cold box is used, in which the H2-CO gas mixture is cooled and hydrogen and CO are separated. The separated hydrogen 15a is fed back to the RWGS reaction 30. From the H2-CO separation, 22.0 kg / h of CO 15b are fed to a phosgene synthesis 9. Here, the CO 15b reacted with 55.78 kg / h of chlorine 10a, which was taken from an HCl recycling process 10. The HCl gas is converted to chlorine by thermocatalytic gas-phase oxidation (Deacon) of HCl from isocyanate production 8. Optionally, the O2 from water electrolysis 20 can be used for the oxidation of HCl gas in the Deacon process 10.

[0263] From the phosgene synthesis 9, 77.78 kg / h of phosgene are taken and reacted in an isocyanate production 8 with 47.92 kg / h of toluene diamine 7a to form 68.35 kg / h of toluene diisocyanate 8a.

[0264] The resulting HCl gas, at a rate of 57.35 kg / h, is purified via low-temperature distillation and fed into a CH production process by thermocatalytic gas-phase oxidation (10). In the thermocatalytic gas-phase oxidation (10), the HCl gas is converted to chlorine and H2O with oxygen at approximately 300°C over a ruthenium oxide-based catalyst. The required oxygen of 12.57 kg / h is taken from the water electrolysis (20).

[0265] The resulting toluene diisocyanate 68.35 kg / h 8a is reacted with the 223.6 kg / h polyol (essentially corresponds to the specification of ARCOL® Polyol 1108) 6a obtained from the process to produce 291.95 kg / h polyurethane material in a PU foam production 52.

[0266] After use of the polyurethane material in various applications in the market 54, it can be collected and recycled to provide the resulting polyurethane material waste after processing and preparation 60 of hydroglycolysis 3.

[0267] The hydrogen 20a is produced in a water electrolysis plant 20 with a capacity of 0.088 MW, using renewable energy. The water electrolysis plant 20 is an alkaline water electrolysis plant operating at a current density of 8 kA / m 2and a cell voltage of 2 V per electrolysis element. 0.088 MW and 14.13 kg / h of water are supplied from the process gas cooling of the process gas conditioning (PGA) 15, the process gas drying of the PGA 15, and externally. 1.57 kg / h of H2 and 12.56 kg / h of oxygen are withdrawn from the water electrolysis. The process according to the invention recycles almost all of the raw materials of the TDI-based PU material, such as the amine and the polyol, thus closing the value chain.

[0268] By using renewable energy in water electrolysis, the CCh footprint of the phosgene produced from CO and CH is further reduced, thus enabling a sustainably produced TDI or the resulting PU material.

[0269] Example 4 (Fig, 2):

[0270] This example corresponds to example 3 except for the implementation of the CO2 reduction.

[0271] For the reduction of CO2 30, a low-temperature CO2 electrolysis is carried out as described in Example 2.

Claims

Patent claims 1. Process for the preparation of phosgene by at least the following steps Producing a CO2 gas stream (31) by at least the following steps: Providing at least one organically modified carbamate; Hydrolysis of the provided at least one organically modified carbamate, at least with formation of organic amino compound and CO2; Separating the CO2 formed to obtain at least one CO2 gas stream; preferably purifying (4) the CO2 gas stream (31) from secondary components, in particular from secondary components selected from at least one compound from the list formed from alcohols, polyethers, hydrocarbons, organic amines, water, sulfur compounds, dust, oxygen, and nitrogen, by means of at least one purification method selected from condensation, adsorption, catalytic gas purification, or gas scrubbing to obtain a purified carbon dioxide (31a); Reduction (6) of CO2 of the at least one produced, optionally purified CO2 gas stream (31, 31a) to carbon monoxide (21a); Synthesis (1) of phosgene (20) from at least the carbon monoxide (21a) and chlorine (22) obtained by said reduction.

2. Process according to claim 1, characterized in that at least one direct process product of a chemolysis of polyurethane material is used as the organically modified carbamate provided, comprising at least the following Process steps: Provision of polyurethane material; Implementation of the provided polyurethane material with at least one Chemolysis reagent selected from (a) a primary or secondary organic amine, (b) an amino alcohol having a primary or secondary amino group or (c) an alcohol having at least one hydroxyl group, to form at least one organically modified carbamate. Process according to one of claims 1 or 2, characterized in that said CO2 gas stream (31) is produced by chemolysis of polyurethane material, comprising at least the steps Provision of polyurethane material; reacting the provided polyurethane material with at least one chemolysis reagent selected from (a) a primary or secondary organic amine, (b) an amino alcohol having a primary or secondary amino group or (c) an alcohol having at least one hydroxyl group, to form at least one organically modified carbamate; Hydrolysis of the previously formed organically modified carbamate to form at least organic amino compound and CO2; Separation of the CO2 formed to obtain at least one CO2 gas stream. Process according to claim 3, characterized in that said conversion of the provided polyurethane material to said organically modified carbamate and said hydrolysis of said carbamate are carried out together in one process step. Process according to one of claims 2 to 4, characterized in that the resulting CO2 gas stream has a temperature of 140 °C to 220 °C, preferably of 170 °C to 200 °C. Process according to one of claims 2 to 5, characterized in that said conversion of the provided polyurethane material to said organically modified carbamate is carried out using at least one catalyst, in particular selected from carbonate, bicarbonate, orthophosphate, monohydrogen orthophosphate, metaphosphate, hydroxide, organic amine, organometallic compounds or mixtures of two or more of the aforementioned catalysts. Process according to one of claims 2 to 6, characterized in that the chemolysis reagent is selected from ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl glycol, triethylene glycol, glycerol, 2-methyl-1,3-propanediol, or mixtures of two or more of the aforementioned alcohols. Process according to one of the preceding claims, characterized in that a purification (4) of secondary components from the CO2 gas stream (31) takes place, and in this process at least the CO2 gas stream is passed through several condensers and cooled, wherein the organic and aqueous components present in the gas stream as secondary components condense, are separated off as a liquid, and after completion of the purification (4), a purified CO2 gas stream (31a) is fed to the reduction (6) to carbon monoxide.Method according to one of the preceding claims, characterized in that a hydrogen stream (29a) is provided and, together with the optionally purified CO2 gas stream (31, 31a), is converted into a product gas (39) containing carbon monoxide (21) and optionally by-products (32) according to the principle of the reverse water gas shift reaction. Method according to claim 9, characterized in that, to provide the hydrogen stream (29a), an electrolysis (5) of water (26) to hydrogen (29) and oxygen (27) is carried out. Method according to claim 10, characterized in that the water electrolysis (5) is carried out using electrical power generated from renewable energy, in particular from renewable energy in the form of wind power, solar energy, or hydropower. Method according to one of the preceding claims, characterized in that the optionally purified CO2 gas stream is converted into a...is introduced into an electrolysis device and reduced to carbon monoxide at an electrode, preferably a gas diffusion electrode. A device for producing phosgene, comprising at least one unit for providing a CO2 gas stream that is the direct product of a process that includes at least the step of hydrolyzing at least one organic compound selected from organically modified carbamate, said unit comprising at least one CCh outlet for said CO2 gas stream;optionally at least one unit for cleaning the CO2 gas stream (31) of secondary components containing at least one unit from the group formed by condensation unit, adsorption unit, gas scrubbing unit or catalytic gas cleaning unit, wherein the unit for cleaning the CO2 gas stream has at least one inlet for the CO2 gas stream (31) as the CO2 gas stream to be cleaned, which inlet is in fluid communication with the CO2 outlet of the unit for providing the CO2 gas stream and wherein the unit for cleaning the CO2 gas stream has at least one outlet for a cleaned CO2 gas stream;at least one unit for reducing the at least one provided, optionally purified, CO2 gas stream (31, 31a) to carbon monoxide (21a), comprising at least one inlet for the CO2 gas stream, which is in fluid communication with at least one outlet of the unit for providing a CO2 gas stream, optionally via the at least one unit for purifying the CO2 gas stream, and comprising at least one outlet for carbon monoxide; at least one unit for producing phosgene, comprising at least one inlet for chlorine gas, which is in fluid communication with a source of chlorine gas, and; at least one inlet for carbon monoxide, which is in fluid communication with at least one outlet for carbon monoxide of the unit for reducing said CO2 gas stream; at least one outlet for phosgene. Apparatus according to claim 13, characterized in that the unit for providing a CO2 gas stream contains a unit for hydrolyzing at least one organic compound, containing at least one hydrolysis device containing at least one inlet for a liquid containing water and chemolysis reagent, at least one inlet for polyurethane material, and at least one outlet for the CO2 gas stream, wherein, in a reaction zone of the hydrolysis device, polyurethane material and said liquid can be contacted, and the formed CO2 gas stream can be discharged through said outlet. Apparatus according to claim 14, characterized inthat the unit for providing a CO2 gas stream contains a unit for hydrolyzing at least one organic compound, comprising at least one chemolysis device, comprising at least one inlet for a liquid containing a chemolysis reagent, at least one inlet for polyurethane material and at least one outlet for organically modified carbamate, wherein in the reaction zone of the reactor, polyurethane material and said liquid are contacted and can be converted to at least one organic compound selected from organically modified carbamate; at least one hydrolysis device, comprising at least one inlet for a chemolysis reagent, at least one inlet for water-containing liquid, organically modified carbamate and at least one outlet for the CO2 gas stream, wherein in a reaction zone of the hydrolysis device, said organically modified carbamate and said water-containing liquid, and the CO2 gas stream formed can be led out through said outlet, wherein the inlet for organically modified carbamate is in fluid communication with the outlet for organically modified carbamate of the chemolysis device.

16. Device according to one of claims 13 to 15, characterized in that the Unit for reducing the at least one provided, optionally purified, CO2 gas stream (31, 31a) is an electrolysis unit with a gas diffusion electrode for CO2 reduction or a reverse water gas shift reactor.

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