Method for removing carbon dioxide from liquid aqueous stream

Abstract

Disclosed is a method for removing carbon dioxide from a liquid aqueous stream comprising at least one hexane-1, 6-diamine species comprising at least one carbon dioxide derivative of hexane-1, 6-diamine, the method comprising providing a liquid aqueous stream exhibiting a carbon dioxide loading amount cL1, where 0.5 < = cL1 < = 2.5, wherein the liquid aqueous flow L1 to be heated has a temperature TL1lt according to (ii) the liquid aqueous flow L1 to be heated; t according to (ii); and heating the liquid aqueous stream at a pressure p > = 0.5 bar (absolute) to a temperature T > = 90 DEG C, thereby obtaining a vapour stream V comprising carbon dioxide and obtaining a liquid aqueous stream L2 exhibiting a carbon dioxide loading cL2, where cL2 < = 0.1.

Description

[0001] The present invention relates to a method for removing carbon dioxide from a liquid aqueous stream comprising at least one hexane-1,6-diamine species, the at least one hexane-1,6-diamine species comprising at least one carbon dioxide derivative of hexane-1,6-diamine. Preferably, the liquid aqueous stream is obtained from a fermentation process.

[0002] Hexamethylenediamine (hereinafter also referred to as HMDA and further as 1,6-diaminohexane or 1,6-hexanediamine) is a compound frequently used as a raw material, particularly for the production of polymers. Most HMDA is used in the production of nylon 66 via condensation with adipic acid. Furthermore, it is used in the production of hexamethylene diisocyanate (HDI) via phosgenation, which is in turn a monomeric raw material for the production of polyurethanes. Furthermore, HMDA serves as a crosslinking agent in epoxy resins, for example.

[0003] At present, the most commonly used commercial method for HMDA manufacture is carried out via the hydrogenation of adiponitrile in ammonia, and adiponitrile is then produced by the hydrocyanation of butadiene. However, bio-based approach is also known and is particularly described in US2017 / 0369913 A1. Usually, in such a fermentation process, carbon dioxide is used, particularly for regulating the pH of the culture medium involved. Therefore, from the fermentation process, an aqueous solution of carbon dioxide derivatives and carbon dioxide adducts (such as carbonate and carbamate) containing HMDA is obtained. However, in downstream applications using HMDA as raw material, free HMDA is used. Therefore, it is necessary to provide a kind of advantageous method for making the derivative and adduct cracking to obtain a solution comprising HMDA in its free form. According to the present invention, such a favorable method is provided.

[0004] The present invention therefore relates to a process for removing carbon dioxide from a liquid aqueous stream L1 comprising at least one hexane-1,6-diamine species comprising at least one carbon dioxide derivative of hexane-1,6-diamine, the process comprising

[0005] (i) providing a carbon dioxide loading capacity c L1 The liquid aqueous stream L1, where c L1 is defined as n L1 (CO2) / n L1 (HMDA), where n L1 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L1, and n L1 (HMDA) is the molar amount of the at least one hexane-1,6-diamine substance in L1, wherein 0.5≤c L1≤2.5, wherein the liquid aqueous stream L1 to be subjected to heating according to (ii) has a temperature T L1 <T according to (ii);

[0006] (ii) heating the liquid aqueous stream L1 provided according to (i) to a temperature T≥90° C. at a pressure p≥0.5 bar (absolute) to obtain a vapor stream V comprising carbon dioxide, and obtaining a vapor stream exhibiting a carbon dioxide loading c L2 The liquid aqueous stream L2, where c L2 is defined as n L2 (CO2) / n L2 (HMDA), where n L2 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L2, and n L2 (HMDA) is the molar amount of the at least one hexane-1,6-diamine species in L2, wherein c L2 ≤0.1.

[0007] As used herein, the term "carbon dioxide derivatives of hexane-1,6-diamine" includes all conceivable carbonates and carbamates of HMDA. Preferably, the term includes hexamethylene-1,6-carbamate (H2N-(CH2)6-NH-COO - ), hexamethylene-1,6-diaminoformate ( - OOC-HN-(CH2)6-NH-COO - ), hexamethylene-1,6-carbamate zwitterion ( + H3N-(CH2)6-NH-COO - ), hexamethylene-1,6-carbonate ( + H3N-(CH2)6-NH3 + CO3 2- ), hexamethylene-1,6-bicarbonate (H2N-(CH2)6-NH3 + HCO3 - ), and hexamethylene-1,6-bis-bicarbonate ( + H3N-(CH2)6-NH3 + (HCO3 -) 2). Preferably, the counterions of hexamethylene-1,6-carbamate and hexamethylene-1,6-dicarbamate are monoprotonated or diprotonated HMDA. Preferably, according to the present invention, 80 to 100 mol%, more preferably 90 to 100 mol%, more preferably 95 to 100 mol% of the at least one carbon dioxide derivative of hexane-1,6-diamine consists of one or more of the following: hexamethylene-1,6-carbamate, hexamethylene-1,6-dicarbamate, hexamethylene-1,6-carbamate zwitterion, hexamethylene-1,6-carbonate, hexamethylene-1,6-bicarbonate, and hexamethylene-1,6-bis-bicarbonate.

[0008] Typically, the at least one hexane-1,6-diamine substance mentioned in the present invention comprises the at least one hexane-1,6-diamine carbon dioxide derivative described above. Optionally, the at least one hexane-1,6-diamine substance further comprises other hexane-1,6-diamine substances, preferably hexane-1,6-diamine free base. According to an embodiment of the present invention, the at least one hexane-1,6-diamine substance is composed of the one or more hexane-1,6-diamine carbon dioxide derivatives and hexane-1,6-diamine free base described above. Preferably, 90 to 100 mol-%, more preferably 95 to 100 mol-%, more preferably 98 to 100 mol-% of the at least one hexane-1,6-diamine substance is composed of the at least one hexane-1,6-diamine carbon dioxide derivative and optionally hexane-1,6-diamine free base.

[0009] The total concentration of the at least one carbon dioxide derivative of hexane-1,6-diamine in the liquid aqueous stream L1 provided according to (i) is preferably in the range of 3 to 30 wt-%, more preferably in the range of 5 to 25 wt-%, more preferably in the range of 7 to 15 wt-%, such as 7 to 9 wt-% or 9 to 11 wt-% or 11 to 13 wt-% or 13 to 15 wt-%. The term "total concentration of the at least one carbon dioxide derivative of hexane-1,6-diamine" as used in this respect is to be understood as being calculated on a CO2-free basis, i.e. the weight of each carbon dioxide derivative of hexane-1,6-diamine is expressed as the weight of HMDA free base, and assuming that the liquid aqueous stream L1 is free of CO2.

[0010] Regarding the carbon dioxide loading c according to (i) L1 , the preferred range is 0.6≤c L1 ≤2.0, more preferably 0.7≤c L1 ≤1.6, such as 0.7≤c L1 ≤1.0 or 1.0≤c L1 ≤1.3 or 1.3≤cL1 ≤1.6.

[0011] Typically, the liquid aqueous stream L1 provided according to (i) may contain, in addition to water, the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base, one or more additional compounds, wherein preferably 90 to 100 wt-%, preferably 95 to 100 wt-%, more preferably 98 to 100 wt-%, more preferably 99 to 100 wt-% of the liquid aqueous stream L1 provided according to (i) consists of water, the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base.

[0012] Preferably, the liquid aqueous stream L1 provided according to (i) has a pH of at least 6. In particular, in the case where the liquid aqueous stream L1 is obtained from a fermentation process, it is preferred that it has a pH in the range from 6 to 10, more preferably in the range from 7 to 9.5, more preferably in the range from 7.5 to 9 (such as 7.5 to 8 or 8 to 8.5 or 8.5 to 9).

[0013] According to (ii), the liquid aqueous stream L1 provided according to (i) is heated to a temperature T of the stream of at least 90 °C at a pressure p ≥ 0.5 bar (absolute pressure), where T > T L1 . Preferably, T L1 is at least 10 °C, more preferably at least 15 °C, more preferably at least 20 °C. The preferred range of T is for example 10 °C to 50 °C or 15 °C to 40 °C or 20 °C to 30 °C. Preferably, 10 °C ≤ T L1 < T, more preferably 15 °C ≤ T L1 < T, more preferably 20 °C ≤ T L1 < T.

[0014] According to (ii), the temperature T to which the stream L1 is heated in the column is preferably in the range from 90 °C to 190 °C, more preferably in the range from 100 °C to 180 °C, more preferably in the range from 110 °C to 170 °C. Thus, the preferred range can be in the range from 110 °C to 120 °C or 120 °C to 130 °C or 130 °C to 140 °C or 140 °C to 150 °C or 150 °C to 160 °C or 160 °C to 170 °C.

[0015] A liquid aqueous strippant L2 with a significantly reduced carbon dioxide loading is obtained from step (ii) of the present invention, because during (ii), the at least one carbon dioxide derivative of HMDA is cleaved, CO2 is released and removed therefrom via the vapor stream V, while an aqueous solution containing HMDA free base is obtained as stream L2. Preferably, the carbon dioxide loading c of stream L2 L2is at most 0.08, more preferably at most 0.06, more preferably at most 0.04, more preferably at most 0.03, more preferably at most 0.02. L2 ≤0.08, more preferably 0≤c L2 ≤0.06, more preferably 0≤c L2 ≤0.04, more preferably 0≤c L2 ≤0.03, more preferably 0≤c L2 ≤0.02.

[0016] According to a first embodiment of the invention, the heating according to (ii) is performed in a stripping column, wherein a stripping medium is used, and wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 into the stripping column, and wherein (ii) comprises

[0017] (ii.1) heating the liquid aqueous stream L1 provided according to (i) to a temperature T of at least 90° C. in a stripping column at a pressure p of at least 0.5 bar abs.;

[0018] (ii.2) A vapor stream V is obtained at the top of the stripping column, which has a temperature T V and contains carbon dioxide, and said vapor stream V is removed from the top of the stripping column;

[0019] (ii.3) A liquid aqueous stream L2 is obtained at the bottom of the stripping column, which has a temperature T L2 and contains hexane-1,6-diamine free base, and said liquid aqueous stream L2 is removed from the bottom of the stripping column;

[0020] and wherein the method further comprises

[0021] (iii.1) subjecting the liquid aqueous stream L2 obtained according to (ii.3) to evaporation in an evaporator E1, thereby obtaining a stream having a temperature T VL2 The water vapor flow V L2 and has temperature T L3 The aqueous liquid stream L3, wherein preferably T VL2 =T L3 ;

[0022] (iii.2) The water vapor stream V obtained according to (iii.1) L2 The feed is returned to the bottom section of the stripping column.

[0023] There are no specific restrictions regarding the stripping medium. Preferably, the stripping medium comprises steam, with 90 to 100 wt.-%, more preferably 95 to 100 wt.-%, and even more preferably 99 to 100 wt.-% of the stripping medium consisting of steam being more preferred. Thus, preferably, 0 to 10 wt.-%, more preferably 0 to 5 wt.-%, and even more preferably 0 to 1 wt.-% of the stripping medium consists of one or more stripping media other than steam, preferably one or more of nitrogen, air, and lean air. Thus, while other stripping media other than steam are conceivable, it is preferred that 100 wt.-% of the stripping medium consists of steam. While this steam can be introduced into the stripping column from one or more suitable external sources, it is preferred that the steam is at least partially, and preferably completely, obtained in situ in the stripping column by heating the liquid aqueous stream L2 to a temperature T in the stripping column.

[0024] According to a preferred embodiment of the invention, the liquid stream L3 obtained from the evaporator E1 in (iii.1) as described above is passed through a heat exchanger H1. In this heat exchanger H1, part of the heat contained in L3 is transferred to another stream, preferably to the stream L1 before being sent to the stripping column, the stream L1 thus being appropriately preheated in H1. Therefore, the process of the invention preferably further comprises

[0025] (iii.3) passing the aqueous liquid stream L3 obtained according to (iii.1) through a heat exchanger H1 to obtain a liquid having a temperature T L4 The flow L4, where T L4 <T L3 ;

[0026] (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed into the stripping column, it is passed through a heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 .

[0027] Preferably, the temperature difference ΔT H1 =T L10 –T L4 , i.e. the temperature difference between the temperature of L1 after passing through H1 and the temperature of flow L4 (i.e. the temperature of flow L3 after it has transferred part of the heat contained therein to L1 in H1), is at most 20 K, more preferably at most 15 K, more preferably at most 10 K, more preferably at most 5 K.

[0028] As for the vapor stream V obtained at the top of the stripping column according to (ii.2), it preferably contains water in addition to carbon dioxide. In order to separate the water from the carbon dioxide, it is preferred to subject the stream V to a suitable separation stage, preferably condensation, from which a water stream depleted in carbon dioxide and a water-depleted carbon dioxide stream are obtained. Therefore, in the preferred case that the vapor stream V contains water in addition to carbon dioxide, the process according to the invention preferably further comprises

[0029] (iv.1) subjecting the vapor stream V obtained according to (ii.2) to condensation in a condenser C1 to obtain a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V .

[0030] Generally, it may be advantageous to operate the stripping column with internal reflux. According to this embodiment, the stream L obtained above according to (iv.1) is V The streams are appropriately split and the corresponding streams obtained are fed back to the stripping column, preferably to the top section of the stripping column. In this case, the process of the invention preferably further comprises

[0031] (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column.

[0032] As far as the corresponding reflux ratio is concerned, there is no specific limitation. Preferably, the reflux ratio is in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:1.

[0033] According to another embodiment of the present invention, the vapor stream V obtained at the top of the stripping column is used to transfer part of its heat to another stream, preferably to the aqueous liquid stream L1 before being conveyed to the stripping column, in a heat exchanger H2. In terms of this embodiment, it is preferred that the heat exchanger H2 is arranged upstream of the heat exchanger H1 according to (iii.4) described above, i.e. the stream L1 is preheated to a first elevated temperature before being conveyed to the stripping column, and the resulting preheated stream is then further preheated to a second elevated temperature, which is higher than the first elevated temperature. Still further, according to this embodiment, it is preferred that the stream obtained from H2 (which has transferred part of its heat to L1) is conveyed to a condenser, from which a water stream depleted in carbon dioxide and a water-depleted carbon dioxide stream are obtained. Therefore, the process of the present invention, in which the vapor stream V obtained according to (ii.2) further comprises water in addition to carbon dioxide, preferably further comprises

[0034] (iv.0) Passing the vapor stream V obtained according to (ii.2) through a heat exchanger H2, thereby obtaining a temperature T HVL <T V a partially condensed stream VL;

[0035] (iv.1) subjecting the stream VL obtained according to (iv.0) to condensation in a condenser C1 to obtain a stream containing water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ;

[0036] The method more preferably further comprises the step of causing the temperature T L100 Before the liquid aqueous stream L1 passes through the heat exchanger H1 according to (iii.4), it is passed through the heat exchanger H2 according to (iv.0) so as to obtain a liquid aqueous stream having a temperature T L10 The liquid aqueous flow L1, where T L10 >T L100 .

[0037] Preferably, the temperature difference ΔT H2 =T L100 –T HVL , i.e. the temperature difference between the temperature of L1 after having passed through H2 and the temperature of stream VL (i.e. the temperature of stream V after having transferred part of the heat contained therein in H2 to L1), is at most 20 K, more preferably at most 15 K, more preferably at most 10 K, more preferably at most 5 K.

[0038] According to the present invention, the latter embodiment may further exhibit a suitable internal reflux to the top of the stripping column. In this respect, it is preferred that the process further comprises after (iv.0) and before (iv.1)

[0039] (iv.2) Splitting the stream VL obtained according to (iv.0) into two streams VL1 and VL2, feeding stream VL1 back into the top section of the stripping column, and subjecting stream VL2 as stream VL according to (iv.1) to condensation in the condenser C1 according to (iv.2).

[0040] As far as the corresponding reflux ratio is concerned, there is no specific limitation. Preferably, the reflux ratio is in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:1.

[0041] According to another embodiment of the invention, the vapor stream obtained at the top of the stripping column is subjected to compression and the corresponding compressed stream obtained is used as heating medium for the evaporator of the stripping column. The cooled compressed stream thus obtained, leaving the evaporator, or a portion thereof, is then preferably fed back to the top of the stripping column. In this case, the process of the invention further comprises

[0042] (v.1) will have temperature T VK and a vapor stream V comprising carbon dioxide and preferably water K Removed from the top of the stripping column, the vapor stream V K preferably has the same chemical composition as vapor stream V;

[0043] (v.2) The stream V removed from the top of the stripping column according to (v.1) is K By means of compressor K1, a temperature T CVK The compressed flow V K , where T CVK >T VK ;

[0044] (v.3) Make the compressed flow V K As heating medium is passed through the evaporator E1 according to (iii.1), thereby obtaining a liquid phase V K (1) and optionally a vapor phase V K (g) Cooled compressed flow V K ;

[0045] (v.4) The liquid phase V obtained according to (v.3) is preferably K (1) or a portion thereof is fed into the top section of the stripping column.

[0046] As indicated in (v.3), the cooled compressed stream VK may also contain a vapor phase in addition to the liquid phase which may be fed back to the top of the column. In this case, it may be preferred if the stream VK is subjected to a suitable gas-liquid separation stage. As far as the vapor phase obtained accordingly is concerned, it may be preferred to combine it with another stream obtained in the process, preferably a vapor stream obtained from a compressor arranged downstream of the heat exchanger H2 as described above. Therefore, the process may preferably further comprise

[0047] (v.5) The vapor phase V obtained according to (v.3) K (g) with the vapor flow V obtained according to (iv.1) V merge.

[0048] According to another embodiment, the method is designed in such a way that the stripping column is appropriately combined with the concentration of the CO2-depleted aqueous solution by evaporation. According to this embodiment, the stripping column is essentially used to strip the CO2 contained in the liquid stream L1, and the corresponding CO2-depleted aqueous stream is then subjected to a downstream evaporation stage operated at a reduced pressure compared to the stripping column. Advantageously, the vapor stream obtained from the top of the stripping column or a portion thereof is used for this evaporation task. Even more preferably, the steam obtained from the evaporation is used to preheat the liquid stream L1 before it is conveyed to the stripping column. According to this method configuration, an efficient and heat-integrated method is provided, which produces a concentrated aqueous solution containing HMDA free base.

[0049] According to this embodiment combining stripping and concentration, the method preferably further comprises

[0050] (iii.3) passing the vapor stream V obtained according to (ii.2) through the evaporator E2, thereby obtaining a temperature T EV <T V Stream V;

[0051] (iii.4) subjecting the aqueous stream L3 obtained according to (iii.1) to evaporation in an evaporator E2 according to (iii.3) to obtain a stream having a temperature T VL3 The water vapor flow V L3 and has temperature T LL3 The aqueous liquid flow L L3 , where preferably T VL3 =T LL3 .

[0052] Further preferably, the method comprises

[0053] (iii.5) The steam-containing stream V obtained according to (iii.4) is L3 Through the heat exchanger H1, a temperature TVL3H The water vapor flow V L3H , where T VL3H <T VL3 ;

[0054] (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed into the stripping column, it is passed through a heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 .

[0055] Still further preferably, the process comprises subjecting the water vapor stream V obtained according to (iii.5) to L3H It undergoes condensation in condenser C2, thereby obtaining a liquid aqueous stream.

[0056] As discussed above with respect to the previous embodiment, the process arrangement combining stripping and condensation may also exhibit the following as an additional feature: the vapor stream obtained from the stripping column is condensed and, further preferably, at least a portion of the correspondingly obtained liquid stream is used for internal reflux. According to this embodiment, in which the vapor stream V obtained according to (iii.3) further comprises water in addition to carbon dioxide, the process preferably further comprises

[0057] (iv.1) subjecting the vapor stream V obtained according to (iii.3) to condensation in a condenser C1 to obtain a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V .

[0058] Further preferably, the method comprises

[0059] (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column.

[0060] As far as the corresponding reflux ratio is concerned, there is no specific limitation. Preferably, the reflux ratio is in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:1.

[0061] According to another preferred embodiment of the present invention, the aqueous solution depleted in carbon dioxide and containing HMDA free base for further downstream use is prepared using a multi-stage evaporation setup. According to this embodiment, step (ii) is carried out in an evaporation unit comprising n evaporation devices E connected in series. j , j = 1 ... n, where n ≥ 2, where the evaporation equipment E j Including heating device E Hj , where the evaporation equipment E j+1 Arranged in the evaporation equipment E j downstream of , wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 for evaporation into evaporation equipment E1;

[0062] where for j = 1…n, (ii) includes

[0063] In the evaporation equipment E j Medium pressure p j The next step will have been fed to the evaporation equipment E j The liquid water stream in the j , thus obtaining the vapor flow V j , the vapor flow V j With temperature T Vj and contains carbon dioxide, and the vapor stream V j From the evaporation equipment E j Removed and obtain liquid aqueous stream L 1j , the liquid aqueous flow L 1j With temperature T L1j And showed carbon dioxide loading c L1j , where c L1j is defined as n L1j (CO2) / n L1j (HMDA), where n L1j (CO2) is L 1j The molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine, and n L1j (HMDA) is L 1j The molar amount of at least one hexane-1,6-diamine substance in the liquid aqueous stream L 1j From the evaporation equipment E j removed; and

[0064] Will be from E j The liquid aqueous stream L removed from 1j Feed to evaporation equipment E j+1 Evaporation is carried out in the Lj As heat source through evaporation equipment E j+1Heating device E Hj+1 , and the flow W Lj+1 From the heating device E Hj+1 Remove

[0065] and where for j=n, (ii) includes

[0066] In the evaporation equipment E n Medium pressure p n The next step will have been fed to the evaporation equipment E n The liquid water stream in the n , thus obtaining the vapor flow V n = V, the vapor flow V has a temperature T V and contains carbon dioxide, and the vapor stream V is passed from the evaporation device E n and obtain a liquid aqueous stream L 1n = L2, the liquid aqueous stream L2 has a temperature T L2 And showed carbon dioxide loading c L2 , and the liquid aqueous stream L2 is taken from the evaporation device E n Remove

[0067] One of the parameter pairs (T j ;p j ) is a parameter pair (T; p) as defined in claim 1, wherein the temperature T ≥ 90°C and the pressure p ≥ 0.5 bar (absolute).

[0068] According to a preferred embodiment of the multi-stage evaporation design, the parameter pair (T1; p1) implemented in the first evaporator E1 is the parameter pair (T; p) as defined above, wherein the temperature T is ≥ 90° C. and the pressure p is ≥ 0.5 bar (absolute). Preferably, the temperature T is in the range of 90° C. to 190° C., more preferably in the range of 110° C. to 190° C., more preferably in the range of 130° C. to 190° C., such as in the range of 130° C. to 150° C. or 150° C. to 170° C. or 170° C. to 190° C.

[0069] Regarding the number n of evaporation stages connected in series, it is preferred that n=7; more preferably n=6; more preferably n=5, more preferably n=4, more preferably n=3 or n=2.

[0070] Preferably, a given evaporator is operated at a pressure lower than the pressure of the corresponding preceding evaporator, ie preferably for j=1...n-1, p j+1 <p j And T j+1 <T j .

[0071] Still further, it is preferred to operate a given evaporator so that the temperature difference between the temperature of the vapor phase obtained from said evaporator and the temperature of the liquid stream obtained from the corresponding next evaporator is within a certain range. In particular, it is preferred that for j=1...n-1, ΔT Ej+1 =T Vj –T L1j+1 In the range of 5K to 10K.

[0072] In particular, for n=2, it is preferred that

[0073] - T1 is in the range of 90°C to 190°C, preferably in the range of 110°C to 190°C, more preferably in the range of 130°C to 190°C;

[0074] - T2 is in the range of 45 to 170°C, preferably in the range of 60 to 170°C, more preferably in the range of 90 to 170°C.

[0075] In particular, for n=3, it is preferred that

[0076] - T1 is in the range of 90°C to 190°C, preferably in the range of 110°C to 190°C, more preferably in the range of 130°C to 190°C;

[0077] - T2 is in the range of 50°C to 160°C, preferably in the range of 70°C to 160°C, more preferably in the range of 90°C to 160°C;

[0078] - T3 is in the range of 35°C to 140°C, preferably in the range of 50°C to 140°C, more preferably in the range of 70°C to 140°C.

[0079] According to the multi-stage evaporation design, the carbon dioxide loading of the liquid stream obtained from a given evaporator is lower than the carbon dioxide loading of the liquid stream obtained from the previous evaporator, so that the liquid stream with the lowest carbon dioxide loading is obtained from the last evaporator, that is, for j=1...n-1, c L1j+1 <c L1j .

[0080] Preferably, in the case where the vapor stream V obtained from the last evaporator further comprises water in addition to carbon dioxide, the method further comprises subjecting this vapor stream V to condensation in a condenser C1, thereby obtaining a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V .

[0081] For certain embodiments discussed above in the context of the stripper design, the multi-evaporation design also allows for providing heat integration including preheating of the stream L1 subjected to the first evaporator. According to this arrangement, the method preferably comprises passing the vapor stream V obtained according to (ii.2) through a heat exchanger H1, thereby obtaining a temperature T VL <T V of the optionally partially condensed stream VL, wherein the process further comprises subjecting the stream VL to a temperature T L10 The liquid aqueous stream L1 passes through the heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 .

[0082] Preferably, the temperature difference ΔT H1 =T L10 –T VL It is at most 20K, more preferably at most 10K, more preferably at most 5K.

[0083] In the case of the first evaporator E1, the heating medium for evaporation purposes is fed from an external source. In particular, the method further comprises making a heating medium having a temperature T S11 Stream S 11 As heat source, the heating device E1 is used as a heat source. H1 , and the flow S 12 From the heating device E H1 Preferably, ΔT E1 =T S12 –T L11 In the range of 5K to 10K. More preferably, the flow S 11 is the vapor flow, and flow S 12 It is steam condensate.

[0084] Generally, according to the present invention, the feed stream, liquid aqueous stream L1, can be obtained from any suitable source. According to a preferred embodiment, stream L1 comprising at least one hexane-1,6-diamine species (which in turn comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is obtainable or obtained by a fermentation process. Therefore, the present invention further relates to a method as described above, wherein providing the liquid aqueous stream L1 according to (i) comprises preparing stream L1 during a fermentation process.

[0085] For such fermentation processes, it is preferred that the genetically engineered microorganisms be cultured or grown in a suitable culture or fermentation medium containing a nitrogen source and a carbon source in a suitable reaction vessel. During the fermentation of the genetically engineered microorganisms producing HMDA, carbon dioxide is used to regulate and control the pH of the culture medium. As for the carbon dioxide, carbon dioxide can be produced metabolically by the microorganisms or artificially. Alternatively, carbon dioxide can be added from a suitable external source. Preferably, the growth conditions and carbon dioxide concentration of the microorganisms are controlled so that the pH is maintained at a desired value for a specific period of time during the fermentation. Typically, during the fermentation process, the pH will increase from a value within the range of about 6.5 to about 7.5 to a pH of about 8.5, because, for example, the buffer is formed by HMDA and carbon dioxide. Once the fermentation is complete, i.e., the at least one hexane-1,6-diamine substance is formed, the cells can be removed, for example, by suitable filtration to separate the crude aqueous solution from the undesirable by-products contained in the retentate. The fermented aqueous solution obtained by such suitable filtration is referred to herein as liquid aqueous stream L1.

[0086] Preferably, according to the present invention, the finally obtained stream L2 or its downstream stream (as above described as stream L3, stream L4 or stream L L3 The stream (as described above, being CO2-depleted and containing free HMDA) is subjected to a suitable post-treatment, more preferably to a suitable separation stage, wherein free HMDA is separated from the stream. Preferably, the separation stage comprises an extraction stage, wherein the stream is contacted with a suitable organic extraction solvent. More preferably, the separation stage further comprises a distillation stage downstream of the extraction stage, wherein the organic effluent stream obtained from the extraction is suitably distilled in order to separate the HMDA from the extraction solvent. It may be preferred to recycle the thus separated extraction solvent back into the extraction stage.

[0087] Thus, according to the invention, stream L2 or a downstream stream obtained therefrom is subjected to extraction, wherein the downstream stream obtained from L2 is stream L3 as defined above, stream L4 as defined above, or stream L5 as defined above. L3 .

[0088] The HMDA thus separated can be used as is or be subjected to further purification, for example in a further downstream distillation stage. The correspondingly obtained HMDA can then be used, for example, as a starting material for the preparation of polyamides such as nylon, polyureas, isocyanates such as hexamethylene diisocyanate, polyurethanes, and copolymers of one or more thereof, as well as for (semi-quantitative) detection reactions of certain sugars such as disaccharides, such as lactose, maltose, cellobiose, lactulose or maltulose.

[0089] The present invention is further illustrated by the following set of examples and combinations of examples obtained by the dependencies and back-references as shown. In particular, it should be noted that in each case where a series of examples is mentioned, for example, in the context of a term such as "a method as described in any one of Examples 1 to 4", each example in this series is intended to be clearly disclosed to the skilled person, that is, the wording of this term should be understood by the skilled person as synonymous with "a method as described in any one of Examples 1, 2, 3 and 4". In addition, it should be clearly pointed out that the following set of examples represents a suitable structural part of the general description of the preferred aspects of the present invention, and therefore appropriately supports but does not represent the claims of the present invention.

[0090] 1. A method for removing carbon dioxide from a liquid aqueous stream L1 comprising at least one hexane-1,6-diamine species, the at least one hexane-1,6-diamine species comprising at least one carbon dioxide derivative of hexane-1,6-diamine, the method comprising

[0091] (i) providing a carbon dioxide loading capacity c L1 The liquid aqueous stream L1, where c L1 is defined as n L1 (CO2) / n L1 (HMDA), where n L1 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L1, and n L1 (HMDA) is the molar amount of the at least one hexane-1,6-diamine substance in L1, wherein 0.5≤c L1 ≤2.5, wherein the liquid aqueous stream L1 to be subjected to heating according to (ii) has a temperature T L1 <T according to (ii);

[0092] (ii) heating the liquid aqueous stream L1 provided according to (i) to a temperature T≥90° C. at a pressure p≥0.5 bar (absolute) to obtain a vapor stream V comprising carbon dioxide, and obtaining a vapor stream exhibiting a carbon dioxide loading c L2 The liquid aqueous stream L2, where c L2 is defined as n L2 (CO2) / n L2 (HMDA), where n L2 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L2, and n L2 (HMDA) is the molar amount of the at least one hexane-1,6-diamine species in L2, wherein c L2 ≤0.1.

[0093] 2. The method according to Example 1, wherein 80 to 100 mol-%, preferably 90 to 100 mol-%, more preferably 95 to 100 mol-% of the at least one carbon dioxide derivative of hexane-1,6-diamine consists of one or more of the following: hexamethylene-1,6-carbamate, hexamethylene-1,6-dicarbamate, hexamethylene-1,6-carbamate zwitterion, hexamethylene-1,6-carbonate, hexamethylene-1,6-bicarbonate, and hexamethylene-1,6-bis-bicarbonate.

[0094] 3. The method according to Example 1 or 2, wherein 90 to 100 mol-%, preferably 95 to 100 mol-%, more preferably 98 to 100 mol-% of the at least one hexane-1,6-diamine substance consists of the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base.

[0095] 4. The method according to any one of Examples 1 to 3, wherein the total concentration of the at least one carbon dioxide derivative of hexane-1,6-diamine in the liquid water stream L1 provided according to (i) is in the range of 3 to 30 wt-%, preferably in the range of 5 to 25 wt-%, more preferably in the range of 7 to 15 wt-% based on the total weight of the stream L1.

[0096] 5. The method according to any one of Examples 1 to 4, wherein 0.6 ≤ c L1 ≤ 2.0, preferably 0.7 ≤ c L1 ≤ 1.6.

[0097] 6. The method according to any one of Examples 1 to 5, wherein 90 to 100 wt-%, preferably 95 to 100 wt-%, more preferably 99 to 100 wt-% of the liquid water stream L1 provided according to (i) consists of water, the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base.

[0098] 7. The method according to any one of Examples 1 to 6, wherein the liquid water stream L1 provided according to (i) has a pH in the range of 6 to 10, preferably in the range of 7 to 9.5, more preferably in the range of 7.5 to 9 at the temperature of L1 at 25 °C.

[0099] 8. The method according to any one of Examples 1 to 7, wherein 10 °C ≤ T L1 < T, preferably 15 °C ≤ T L1 < T, more preferably 20 °C ≤ T L1 < T.

[0100] 9. The process of any one of embodiments 1 to 8, wherein the temperature T according to (ii) is in the range of 90°C to 190°C, preferably in the range of 100°C to 180°C, more preferably in the range of 110°C to 170°C.

[0101] 10. The method of any one of embodiments 1 to 9, wherein c L2 ≤0.08, preferably c L2 ≤0.06, more preferably c L2 ≤0.04, more preferably c L2 ≤0.02.

[0102] 11. The method of any one of embodiments 1 to 10, wherein step (ii) is performed in a stripping column using a stripping medium, wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 to the stripping column, and wherein (ii) comprises

[0103] (ii.1) heating the liquid aqueous stream L1 provided according to (i) to a temperature T of at least 90° C. in a stripping column at a pressure p of at least 0.5 bar abs.;

[0104] (ii.2) A vapor stream V is obtained at the top of the stripping column, which has a temperature T V and contains carbon dioxide, and said vapor stream V is removed from the top of the stripping column;

[0105] (ii.3) A liquid aqueous stream L2 is obtained at the bottom of the stripping column, which has a temperature T L2 and contains hexane-1,6-diamine free base, and said liquid aqueous stream L2 is removed from the bottom of the stripping column;

[0106] The method further comprises

[0107] (iii.1) subjecting the liquid aqueous stream L2 obtained according to (ii.3) to evaporation in an evaporator E1, thereby obtaining a stream having a temperature T VL2 The water vapor flow V L2 and has temperature T L3 The aqueous liquid stream L3, wherein preferably T VL2 =T L3 ;

[0108] (iii.2) The water vapor stream V obtained according to (iii.1) L2 The feed is returned to the bottom section of the stripping column.

[0109] 12. The process according to embodiment 11, wherein the stripping medium comprises steam, wherein preferably 90 to 100 wt-%, more preferably 95 to 100 wt-%, more preferably 99 to 100 wt-% of the stripping medium consists of steam.

[0110] 13. The process according to embodiment 12, wherein the steam is obtained at least partially, preferably completely, in situ in the stripping column by heating the liquid aqueous stream L1 to a temperature T in the stripping column.

[0111] 14. The process of any one of embodiments 11 to 13, wherein 0 to 10 wt-%, preferably 0 to 5 wt-%, more preferably 0 to 1 wt-% of the stripping medium consists of one or more of nitrogen, air and lean air.

[0112] 15. The method of any one of embodiments 11 to 14, further comprising

[0113] (iii.3) passing the aqueous liquid stream L3 obtained according to (iii.1) through a heat exchanger H1 to obtain a liquid having a temperature T L4 The flow L4, where T L4 <T L3 ;

[0114] (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed into the stripping column, it is passed through a heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 .

[0115] 16. The method of embodiment 15, wherein according to (iii.4), ΔT H1 =T L10 –T L4 , and where ΔT H1 ≤20K, preferably ΔT H1 ≤10K, more preferably ΔT H1 ≤5K.

[0116] 17. The process of any one of embodiments 11 to 16, wherein the vapor stream V obtained according to (ii.2) further comprises water in addition to carbon dioxide, the process further comprising

[0117] (iv.1) subjecting the vapor stream V obtained according to (ii.2) to condensation in a condenser C1 to obtain a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V .

[0118] 18. The method of embodiment 17, further comprising

[0119] (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column.

[0120] 19. The method of embodiment 18, wherein the reflux ratio is in the range of 0.01:1 to 1:1, preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:1.

[0121] 20. The process of any one of embodiments 11 to 16, wherein the vapor stream V obtained according to (ii.2) further comprises water in addition to carbon dioxide, the process further comprising

[0122] (iv.0) Passing the vapor stream V obtained according to (ii.2) through a heat exchanger H2, thereby obtaining a temperature T HVL <T V a partially condensed stream VL;

[0123] (iv.1) subjecting the stream VL obtained according to (iv.0) to condensation in a condenser C1 to obtain a stream containing water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ;

[0124] The method further comprises the step of causing the L100 Before the liquid aqueous stream L1 passes through the heat exchanger H1 according to (iii.4), it is passed through the heat exchanger H2 according to (iv.0) so as to obtain a liquid aqueous stream having a temperature T L10 The liquid aqueous flow L1, where T L10 >T L100 .

[0125] 21. The method of embodiment 20, wherein ΔT H2 =T L100 –T HVL , and where ΔT H2 ≤20K, preferably ΔT H1 ≤10K, more preferably ΔT H1 ≤5K.

[0126] 22. The method of embodiment 20 or 21, further comprising after (iv.0) and before (iv.1):

[0127] (iv.2) Splitting the stream VL obtained according to (iv.0) into two streams VL1 and VL2, feeding stream VL1 back into the top section of the stripping column, and subjecting stream VL2 as stream VL according to (iv.1) to condensation in the condenser C1 according to (iv.2).

[0128] 23. The method of embodiment 22, wherein the reflux ratio is in the range of 0.01:1 to 1:1, preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:1.

[0129] 24. The method of any one of embodiments 11 to 23, further comprising

[0130] (v.1) will have temperature T VK and a vapor stream V comprising carbon dioxide and preferably water K Removed from the top of the stripping column, the vapor stream V K preferably has the same chemical composition as vapor stream V;

[0131] (v.2) The stream V removed from the top of the stripping column according to (v.1) is K By means of compressor K1, a temperature T CVK The compressed flow V K , where T CVK >T VK ;

[0132] (v.3) Make the compressed flow V K As heating medium is passed through the evaporator E1 according to (iii.1), thereby obtaining a liquid phase V K (1) and optionally a vapor phase V K (g) Cooled compressed flow V K ;

[0133] (v.4) The liquid phase V obtained according to (v.3) is preferably K (1) or a portion thereof is fed into the top section of the stripping column.

[0134] 25. The method of embodiment 24, when embodiment 24 is dependent upon embodiment 17, further comprising:

[0135] (v.5) The vapor phase V obtained according to (v.3) K (g) with the vapor flow V obtained according to (iv.1) V merge.

[0136] 26. The method of any one of embodiments 11 to 14, further comprising

[0137] (iii.3) passing the vapor stream V obtained according to (ii.2) through the evaporator E2, thereby obtaining a temperature T EV <T V Stream V;

[0138] (iii.4) subjecting the aqueous stream L3 obtained according to (iii.1) to evaporation in an evaporator E2 according to (iii.3) to obtain a stream having a temperature T VL3 The water vapor flow V L3 and has temperature T LL3 The aqueous liquid flow L L3 , where preferably T VL3 =T LL3 .

[0139] 27. The method of embodiment 26, further comprising

[0140] (iii.5) The steam-containing stream V obtained according to (iii.4) is L3 Through the heat exchanger H1, a temperature T VL3H The water vapor flow V L3H , where T VL3H <T VL3 ;

[0141] (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed into the stripping column, it is passed through a heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 .

[0142] 28. The method of embodiment 27, further comprising subjecting the water vapor stream V obtained according to (iii.5) to L3H It undergoes condensation in condenser C2, thereby obtaining a liquid aqueous stream.

[0143] 29. The method of any one of embodiments 26 to 28, wherein the vapor stream V obtained according to (iii.3) further comprises water in addition to carbon dioxide, the method further comprising

[0144] (iv.1) subjecting the vapor stream V obtained according to (iii.3) to condensation in a condenser C1 to obtain a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in waterV .

[0145] 30. The method of embodiment 29, further comprising

[0146] (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column.

[0147] 31. The method of embodiment 30, wherein the reflux ratio is in the range of 0.01:1 to 1:1, preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:1.

[0148] 32. The method of any one of embodiments 1 to 10, wherein step (ii) is performed in an evaporation unit comprising n evaporation devices E connected in series. j , j = 1 ... n, where n ≥ 2, where the evaporation equipment E j Including heating device E Hj , where the evaporation equipment E j+1 Arranged in the evaporation equipment E j downstream of , wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 for evaporation into evaporation equipment E1;

[0149] where for j = 1…n, (ii) includes

[0150] In the evaporation equipment E j Medium pressure p j The next step will have been fed to the evaporation equipment E j The liquid water stream in the j , thus obtaining the vapor flow V j , the vapor flow V j With temperature T Vj and contains carbon dioxide, and the vapor stream V j From the evaporation equipment E j Removed and obtain liquid aqueous stream L 1j , the liquid aqueous flow L 1j With temperature T L1j And showed carbon dioxide loading c L1j , where c L1j is defined as n L1j (CO2) / n L1j (HMDA), where n L1j (CO2) is L 1jThe molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine, and n L1j (HMDA) is L 1j The molar amount of at least one hexane-1,6-diamine substance in the liquid aqueous stream L 1j From the evaporation equipment E j removed; and

[0151] Will be from E j The liquid aqueous stream L removed from 1j Feed to evaporation equipment E j+1 Evaporation is carried out in the Lj As heat source through evaporation equipment E j+1 Heating device E Hj+1 , and the flow W Lj+1 From the heating device E Hj+1 Remove

[0152] and where for j = n, (ii) includes

[0153] In the evaporation equipment E n Medium pressure p n The next step will have been fed to the evaporation equipment E n The liquid water stream in the n , thus obtaining the vapor flow V n = V, the vapor flow V has a temperature T V and contains carbon dioxide, and the vapor stream V is passed from the evaporation device E n and obtain a liquid aqueous stream L 1n = L2, the liquid aqueous stream L2 has a temperature T L2 And showed carbon dioxide loading c L2 , and the liquid aqueous stream L2 is taken from the evaporation device E n Remove

[0154] One of the parameter pairs (T j ;p j ) is a parameter pair (T; p) as defined in claim 1, wherein the temperature T ≥ 90°C and the pressure p ≥ 0.5 bar (absolute).

[0155] 33. The method of embodiment 32, wherein the parameter pair (T1; p1) is the parameter pair (T; p) as defined in embodiment 1, wherein the temperature T ≥ 90°C and the pressure p ≥ 0.5 bar (absolute).

[0156] 34. The method of embodiment 33, wherein T is in the range of 90°C to 190°C, preferably in the range of 110°C to 190°C, more preferably in the range of 130°C to 190°C.

[0157] 35. The method of any one of embodiments 32 to 34, wherein n=7; preferably wherein n=6; more preferably wherein n=5, more preferably wherein n=4, more preferably wherein n=3 or n=2.

[0158] 36. The method of any one of embodiments 32 to 35, wherein for j=1...n-1, p j+1 <p j And T j+1 <T j .

[0159] 37. The method of embodiment 36, wherein for j=1...n-1, ΔT Ej+1 =T Vj –T L1j+1 In the range of 5K to 10K.

[0160] 38. The method of any one of embodiments 32 to 37, wherein n=2, and wherein

[0161] - T1 is in the range of 90°C to 190°C, preferably in the range of 110°C to 190°C, more preferably in the range of 130°C to 190°C;

[0162] - T2 is in the range of 45 to 170°C, preferably in the range of 60 to 170°C, more preferably in the range of 90 to 170°C.

[0163] 39. The method of any one of embodiments 32 to 37, wherein n=3, and wherein

[0164] - T1 is in the range of 90°C to 190°C, preferably in the range of 110°C to 190°C, more preferably in the range of 130°C to 190°C;

[0165] - T2 is in the range of 50°C to 160°C, preferably in the range of 70°C to 160°C, more preferably in the range of 90°C to 160°C;

[0166] - T3 is in the range of 35°C to 140°C, preferably in the range of 50°C to 140°C, more preferably in the range of 70°C to 140°C.

[0167] 40. The method of any one of embodiments 32 to 39, wherein for j=1...n-1, c L1j+1 <c L1j .

[0168] 41. The method of any one of embodiments 32 to 40, wherein the vapor stream V further comprises water in addition to carbon dioxide, the method further comprising subjecting the vapor stream V to condensation in a condenser C1, thereby obtaining a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V .

[0169] 42. The method of any one of embodiments 32 to 40, further comprising passing the vapor stream V obtained according to (ii.2) through a heat exchanger H1, thereby obtaining a temperature T VL <T V of the optionally partially condensed stream VL, wherein the process further comprises subjecting the stream VL to a temperature T L10 The liquid aqueous stream L1 passes through the heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 .

[0170] 43. The method of embodiment 42, wherein ΔT H1 =T L10 –T VL , and where ΔT H1 ≤20K, preferably ΔT H1 ≤10K, more preferably ΔT H1 ≤5K.

[0171] 44. The method of any one of embodiments 32 to 43, further comprising: S11 Stream S 11 As heat source, the heating device E1 of the evaporation device H1 , and the flow S 12 From the heating device E H1 Remove from .

[0172] 45. The method of embodiment 44, wherein ΔT E1 =T S12 –T L11 In the range of 5K to 10K.

[0173] 46. The method of embodiment 44 or 45, wherein the stream S 11 It is a steam flow.

[0174] 47. The method of any one of embodiments 1 to 46, wherein the liquid aqueous stream L1 is obtained from a fermentation process.

[0175] 48. The method of any one of embodiments 1 to 47, wherein stream L2 or a downstream stream obtained therefrom is subjected to extraction.

[0176] 49. The method of embodiment 48, wherein the downstream stream obtained from L2 is stream L3 as defined in embodiment 11, stream L4 as defined in embodiment 8, or stream L as defined in embodiment 26. L3 .

[0177] 50. A method for removing carbon dioxide from a liquid aqueous stream L1 comprising at least one hexane-1,6-diamine species, the at least one hexane-1,6-diamine species comprising at least one carbon dioxide derivative of hexane-1,6-diamine, the method comprising

[0178] (i) providing a carbon dioxide loading capacity c L1 The liquid aqueous stream L1, where c L1 is defined as n L1 (CO2) / n L1 (HMDA), where n L1 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L1, and n L1 (HMDA) is the molar amount of the at least one hexane-1,6-diamine substance in L1, wherein 0.5≤c L1 ≤2.5, wherein the liquid aqueous stream L1 to be subjected to heating according to (ii) has a temperature T L1 <T according to (ii);

[0179] (ii) heating the liquid aqueous stream L1 provided according to (i) to a temperature T≥90° C. at a pressure p≥0.5 bar (absolute) to obtain a vapor stream V comprising carbon dioxide, and obtaining a vapor stream exhibiting a carbon dioxide loading c L2 The liquid aqueous stream L2, where c L2 is defined as n L2 (CO2) / n L2 (HMDA), where n L2 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L2, and n L2 (HMDA) is the molar amount of the at least one hexane-1,6-diamine species in L2, wherein c L2 ≤0.1.

[0180] wherein step (ii) is carried out in a stripping column using a stripping medium, wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 to the stripping column, and wherein (ii) comprises

[0181] (ii.1) heating the liquid aqueous stream L1 provided according to (i) to a temperature T of at least 90° C. in a stripping column at a pressure p of at least 0.5 bar abs.;

[0182] (ii.2) A vapor stream V is obtained at the top of the stripping column, which has a temperature T V and contains carbon dioxide, and said vapor stream V is removed from the top of the stripping column;

[0183] (ii.3) A liquid aqueous stream L2 is obtained at the bottom of the stripping column, which has a temperature T L2 and contains hexane-1,6-diamine free base, and said liquid aqueous stream L2 is removed from the bottom of the stripping column;

[0184] The method further comprises

[0185] (iii.1) subjecting the liquid aqueous stream L2 obtained according to (ii.3) to evaporation in an evaporator E1, thereby obtaining a stream having a temperature T VL2 The water vapor flow V L2 and has temperature T L3 The aqueous liquid stream L3, wherein preferably T VL2 =T L3 ;

[0186] (iii.2) The water vapor stream V obtained according to (iii.1) L2 The feed is returned to the bottom section of the stripping column;

[0187] wherein the stripping medium preferably comprises steam, wherein more preferably 90 to 100 wt-%, more preferably 95 to 100 wt-%, more preferably 99 to 100 wt-% of the stripping medium consists of steam, and

[0188] The steam is preferably obtained at least partly, more preferably completely, in situ in the stripping column by heating the liquid aqueous stream L1 to a temperature T in the stripping column.

[0189] 51. The method of embodiment 50, further comprising

[0190] (iii.3) passing the aqueous liquid stream L3 obtained according to (iii.1) through a heat exchanger H1 to obtain a liquid having a temperature T L4 The flow L4, where T L4 <T L3 ;

[0191] (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed into the stripping column, it is passed through a heat exchanger H1 to obtain a liquid having a temperature T L1The liquid aqueous flow L1, where T L1 >T L10 ;

[0192] According to (iii.4), ΔT H1 =T L10 –T L4 , and wherein preferably ΔT H1 ≤20K, more preferably ΔT H1 ≤10K, more preferably ΔT H1 ≤5K.

[0193] 52. The method of embodiment 50 or 51, wherein the vapor stream V obtained according to (ii.2) further comprises water in addition to carbon dioxide, the method further comprising

[0194] (iv.1) subjecting the vapor stream V obtained according to (ii.2) to condensation in a condenser C1 to obtain a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ;

[0195] Wherein the method preferably further comprises

[0196] (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column, wherein the reflux ratio is preferably in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:1.

[0197] 53. The method of embodiment 50 or 51, wherein the vapor stream V obtained according to (ii.2) further comprises water in addition to carbon dioxide, the method further comprising

[0198] (iv.0) Passing the vapor stream V obtained according to (ii.2) through a heat exchanger H2, thereby obtaining a temperature T HVL <T V a partially condensed stream VL;

[0199] (iv.1) subjecting the stream VL obtained according to (iv.0) to condensation in a condenser C1 to obtain a stream containing water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ;

[0200] The method further comprises the step of causing the L100 Before the liquid aqueous stream L1 passes through the heat exchanger H1 according to (iii.4), it is passed through the heat exchanger H2 according to (iv.0) so as to obtain a liquid aqueous stream having a temperature T L10 The liquid aqueous flow L1, where T L10 >T L100 .

[0201] where ΔT H2 =T L100 –T HVL , and wherein preferably ΔT H2 ≤20K, more preferably ΔT H1 ≤10K, more preferably ΔT H1 ≤5K.

[0202] 54. The method of embodiment 53, further comprising after (iv.0) and before (iv.1):

[0203] (iv.2) dividing the stream VL obtained according to (iv.0) into two streams VL1 and VL2, feeding stream VL1 back into the top section of the stripping column, and subjecting stream VL2 to condensation in a condenser C1 according to (iv.2) as stream VL according to (iv.1);

[0204] The reflux ratio is preferably in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, and more preferably in the range of 0.05:1 to 0.2:1.

[0205] 55. The method of any one of embodiments 50 to 54, further comprising

[0206] (v.1) will have temperature T VK and a vapor stream V comprising carbon dioxide and preferably water K Removed from the top of the stripping column, the vapor stream V K preferably has the same chemical composition as vapor stream V;

[0207] (v.2) The stream V removed from the top of the stripping column according to (v.1) is K By means of compressor K1, a temperature T CVK The compressed flow V K , where T CVK >T VK ;

[0208] (v.3) Make the compressed flow V KAs heating medium is passed through the evaporator E1 according to (iii.1), thereby obtaining a liquid phase V K (1) and optionally a vapor phase V K (g) Cooled compressed flow V K ;

[0209] (v.4) The liquid phase V obtained according to (v.3) is preferably K (1) or a portion thereof is fed into the top section of the stripping column.

[0210] 56. The method of embodiment 50, further comprising

[0211] (iii.3) passing the vapor stream V obtained according to (ii.2) through the evaporator E2, thereby obtaining a temperature T EV <T V Stream V;

[0212] (iii.4) subjecting the aqueous stream L3 obtained according to (iii.1) to evaporation in an evaporator E2 according to (iii.3) to obtain a stream having a temperature T VL3 The water vapor flow V L3 and has temperature T LL3 The aqueous liquid flow L L3 , where preferably T VL3 =T LL3 ;

[0213] The method preferably further comprises

[0214] (iii.5) The steam-containing stream V obtained according to (iii.4) is L3 Through the heat exchanger H1, a temperature T VL3H The water vapor flow V L3H , where T VL3H <T VL3 ;

[0215] (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed into the stripping column, it is passed through a heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 ;

[0216] wherein the water vapor stream V obtained according to (iii.5) is preferably L3H It undergoes condensation in condenser C2, thereby obtaining a liquid aqueous stream.

[0217] 57. The method of embodiment 56, wherein the vapor stream V obtained according to (iii.3) further comprises water in addition to carbon dioxide, the method further comprising

[0218] (iv.1) subjecting the vapor stream V obtained according to (iii.3) to condensation in a condenser C1 to obtain a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ;

[0219] The method preferably further comprises

[0220] (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column;

[0221] The reflux ratio is preferably in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, and more preferably in the range of 0.05:1 to 0.2:1.

[0222] 58. The method of any one of embodiments 50 to 57, wherein 80 to 100 mol-%, preferably 90 to 100 mol-%, more preferably 95 to 100 mol-% of the at least one carbon dioxide derivative of hexane-1,6-diamine consists of one or more of hexamethylene-1,6-carbamate, hexamethylene-1,6-dicarbamate, hexamethylene-1,6-carbamate zwitterion, hexamethylene-1,6-carbonate, hexamethylene-1,6-bicarbonate, and hexamethylene-1,6-bis-bicarbonate;

[0223] wherein preferably 90 to 100 mol-%, more preferably 95 to 100 mol-%, more preferably 98 to 100 mol-% of the at least one hexane-1,6-diamine species consists of the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base.

[0224] 59. The method of any one of embodiments 50 to 58, wherein 0.6 ≤ c L1 ≤2.0, preferably 0.7≤c L1 ≤1.6.

[0225] 60. The method according to any one of Examples 50 to 59, wherein 90 to 100% by weight, preferably 95 to 100% by weight, more preferably 99 to 100% by weight of the liquid aqueous stream L1 provided according to (i) consists of water, the at least one carbon dioxide derivative of hexane-1,6-diamine, and optionally the free base of hexane-1,6-diamine;

[0226] wherein the liquid aqueous stream L1 provided according to (i) has a pH preferably in the range from 6 to 10, more preferably in the range from 7 to 9.5, more preferably in the range from 7.5 to 9 at the temperature of L1 at 25 °C.

[0227] 61. The method according to any one of Examples 50 to 60, wherein 10 °C ≤ T L1 < T, preferably 15 °C ≤ T L1 < T, more preferably 20 °C ≤ T L1 < T;

[0228] wherein the temperature T according to (ii) is preferably in the range from 90 °C to 190 °C, more preferably in the range from 100 °C to 180 °C, more preferably in the range from 110 °C to 170 °C.

[0229] 62. The method according to any one of Examples 50 to 61, wherein c L2 ≤ 0.08, preferably c L2 ≤ 0.06, more preferably c L2 ≤ 0.04, more preferably c L2 ≤ 0.02.

[0230] 63. The method according to any one of Examples 50 to 62, wherein the liquid aqueous stream L1 is obtainable or obtained by a fermentation process, and wherein the stream L2 or a downstream stream obtained therefrom is subjected to extraction, wherein the downstream stream obtained from L2 is the stream L3 as defined in Example 50, the stream L4 as defined in Example 51, or the stream L as defined in Example 56 L3 .

[0231] 64. A method for removing carbon dioxide from a liquid aqueous stream L1 comprising at least one hexane-1,6-diamine substance, the at least one hexane-1,6-diamine substance comprising at least one carbon dioxide derivative of hexane-1,6-diamine, the method comprising

[0232] (i) providing a liquid aqueous stream L1 exhibiting a carbon dioxide loading c L1 where c L1 is defined as n L1 (CO2) / n L1 (HMDA), where n L1(CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L1, and n L1 (HMDA) is the molar amount of the at least one hexane-1,6-diamine substance in L1, wherein 0.5≤c L1 ≤2.5, wherein the liquid aqueous stream L1 to be subjected to heating according to (ii) has a temperature T L1 <T according to (ii);

[0233] (ii) heating the liquid aqueous stream L1 provided according to (i) to a temperature T≥90° C. at a pressure p≥0.5 bar (absolute) to obtain a vapor stream V comprising carbon dioxide, and obtaining a vapor stream exhibiting a carbon dioxide loading c L2 The liquid aqueous stream L2, where c L2 is defined as n L2 (CO2) / n L2 (HMDA), where n L2 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L2, and n L2 (HMDA) is the molar amount of the at least one hexane-1,6-diamine species in L2, wherein c L2 ≤0.1,

[0234] Wherein step (ii) is carried out in an evaporation unit, which comprises n evaporation devices E connected in series j , j = 1 ... n, where n ≥ 2, where the evaporation equipment E j Including heating device E Hj , where the evaporation equipment E j+1 Arranged in the evaporation equipment E j downstream of , wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 for evaporation into evaporation equipment E1;

[0235] where for j = 1…n, (ii) includes

[0236] In the evaporation equipment E j Medium pressure p j The next step will have been fed to the evaporation equipment E j The liquid water stream in the j , thus obtaining the vapor flow V j , the vapor flow V j With temperature T Vj and contains carbon dioxide, and the vapor stream V j From the evaporation equipment E j Removed and obtain liquid aqueous stream L 1j, the liquid aqueous flow L 1j With temperature T L1j And showed carbon dioxide loading c L1j , where c L1j is defined as n L1j (CO2) / n L1j (HMDA), where n L1j (CO2) is L 1j The molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine, and n L1j (HMDA) is L 1j The molar amount of at least one hexane-1,6-diamine substance in the liquid aqueous stream L 1j From the evaporation equipment E j removed; and

[0237] Will be from E j The liquid aqueous stream L removed from 1j Feed to evaporation equipment E j+1 Evaporation is carried out in the Lj As heat source through evaporation equipment E j+1 Heating device E Hj+1 , and the flow W Lj+1 From the heating device E Hj+1 Remove

[0238] and where for j = n, (ii) includes

[0239] In the evaporation equipment E n Medium pressure p n The next step will have been fed to the evaporation equipment E n The liquid water stream in the n , thus obtaining the vapor flow V n = V, the vapor flow V has a temperature T V and contains carbon dioxide, and the vapor stream V is passed from the evaporation device E n and obtain a liquid aqueous stream L 1n = L2, the liquid aqueous stream L2 has a temperature T L2 And showed carbon dioxide loading c L2 , and the liquid aqueous stream L2 is taken from the evaporation device E n Remove

[0240] One of the parameter pairs (T j ;p j ) is the parameter pair (T; p) as defined in Example 1, wherein the temperature T ≥ 90°C and the pressure p ≥ 0.5 bar (absolute);

[0241] Preferably wherein n=7; more preferably wherein n=6; more preferably wherein n=5, more preferably wherein n=4, more preferably wherein n=3 or n=2.

[0242] 65. The method of embodiment 64, wherein the parameter pair (T1; p1) is the parameter pair (T; p) as defined in embodiment 1, wherein the temperature T ≥ 90°C and the pressure p ≥ 0.5 bar (absolute);

[0243] Wherein T is preferably in the range of 90°C to 190°C, more preferably in the range of 110°C to 190°C, and further preferably in the range of 130°C to 190°C.

[0244] 66. The method of embodiment 64 or 65, wherein for j=1...n-1, p j+1 <p j ;c L1j+1 <c L1j And T j+1 <T j ; and where for j=1…n-1, ΔT Ej+1 =T Vj –T L1j+1 Preferably in the range of 5K to 10K.

[0245] 67. The method of any one of embodiments 64 to 66, wherein the vapor stream V further comprises water in addition to carbon dioxide, the method further comprising subjecting the vapor stream V to condensation in a condenser C1, thereby obtaining a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V .

[0246] 68. The method of any one of embodiments 64 to 66, further comprising passing the vapor stream V obtained according to (ii.2) through a heat exchanger H1, thereby obtaining a vapor stream having a temperature T VL <T V of the optionally partially condensed stream VL, wherein the process further comprises subjecting the stream VL to a temperature T L10 The liquid aqueous stream L1 passes through the heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous flow L1, where T L1 >T L10 .

[0247] 69. The method according to any one of Examples 64 to 68, wherein 80 to 100 mol-%, preferably 90 to 100 mol-%, more preferably 95 to 100 mol-% of the at least one carbon dioxide derivative of hexane-1,6-diamine consists of one or more of the following: hexamethylene-1,6-carbamate, hexamethylene-1,6-dicarbamate, hexamethylene-1,6-carbamate zwitterion, hexamethylene-1,6-carbonate, hexamethylene-1,6-bicarbonate, and hexamethylene-1,6-bis-bicarbonate;

[0248] where preferably 90 to 100 mol-%, more preferably 95 to 100 mol-%, more preferably 98 to 100 mol-% of the at least one hexane-1,6-diamine substance consists of the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base.

[0249] 70. The method according to any one of Examples 64 to 69, wherein 0.6 ≤ c L1 ≤ 2.0, preferably 0.7 ≤ c L1 ≤ 1.6.

[0250] 71. The method according to any one of Examples 64 to 69, wherein 90 to 100 wt-%, preferably 95 to 100 wt-%, more preferably 99 to 100 wt-% of the liquid water stream L1 provided according to (i) consists of water, the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base;

[0251] where the liquid water stream L1 provided according to (i) has a pH preferably in the range of 6 to 10, more preferably in the range of 7 to 9.5, more preferably in the range of 7.5 to 9 at the temperature of L1 at 25 °C.

[0252] 72. The method according to any one of Examples 64 to 71, wherein 10 °C ≤ T L1 < T, preferably 15 °C ≤ T L1 < T, more preferably 20 °C ≤ T L1 < T;

[0253] where the temperature T according to (ii) is preferably in the range of 90 °C to 190 °C, more preferably in the range of 100 °C to 180 °C, more preferably in the range of 110 °C to 170 °C.

[0254] 73. The method according to any one of Examples 64 to 72, wherein c L2 ≤ 0.08, preferably c L2 ≤ 0.06, more preferably c L2 ≤ 0.04, more preferably cL2 ≤0.02.

[0255] In the context of the present invention, the term "X is one or more of A, B, and C", where X is a given feature and each of A, B, and C represents a specific implementation of the feature, should be understood as disclosing that X is A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. In this respect, it should be noted that a skilled person is able to convert the above abstract terms into concrete examples, for example, where X is temperature and A, B, and C are specific temperatures such as 10°C, 20°C, and 30°C. In this regard, it is further noted that the skilled person is able to expand the above terms to fewer specific implementations of the features, such as “X is one or more of A and B”, which discloses that X is A, or B, or A and B, or to more specific implementations of the features, such as “X is one or more of A, B, C, and D”, which discloses that X is A, or B, or C, or D, or A and B, or A and C, or A and D, or B and C, or B and D, or C and D, or A and B and C, or A and B and D, or B and C and D. BRIEF DESCRIPTION OF THE DRAWINGS

[0256] Figure 1 is a schematic diagram of the method according to the present invention

[0257] according to Figure 1 , an aqueous liquid stream L1 comprising at least one hexane-1,6-diamine species comprising at least one carbon dioxide derivative of hexane-1,6-diamine is passed to the top section of a stripping column. At the top of the stripping column, a vapor stream V comprising carbon dioxide is obtained and removed. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed and then passed to an evaporator E1 where L2 is heated to obtain a vapor stream V L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes.

[0258] Figure 2 is a schematic diagram of the method according to the present invention

[0259] according to Figure 2An aqueous liquid stream L1 comprising at least one hexane-1,6-diamine species, comprising at least one carbon dioxide derivative of hexane-1,6-diamine, is passed to the top section of a stripping column. At the top of the stripping column, a vapor stream V comprising carbon dioxide is obtained and removed. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed from the stripping column. Liquid stream L2 is split, and a portion of L2 is passed to evaporator E1, where it is heated to obtain vapor stream V. L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes.

[0260] Figure 3 is a schematic diagram of a method according to the invention comprising preheating of the liquid stream L1

[0261] according to Figure 3 An aqueous liquid stream L1 containing at least one hexane-1,6-diamine substance (which contains at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a heat exchanger H1 and the correspondingly heated stream L1 is conveyed to the top section of a stripping column. At the top of the stripping column, a vapor stream V containing carbon dioxide is obtained and removed. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed from the stripping column. The liquid stream L2 is conveyed to an evaporator E1, where it is heated to obtain a vapor stream V. L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. Stream L3 is used as heating medium in heat exchanger H1 for preheating stream L1 and obtaining a correspondingly cooled stream L4.

[0262] Figure 4 is a schematic diagram of a method according to the invention comprising preheating of the liquid stream L1 and further comprising recirculating

[0263] according to Figure 4 , an aqueous liquid stream L1 containing at least one hexane-1,6-diamine substance (which contains at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a heat exchanger H1, and the corresponding heated stream L1 is sent to the top section of a stripping column. At the top of the stripping column, a vapor stream V containing carbon dioxide is obtained and removed. The vapor stream V is then sent to a condenser C1, and a vapor stream V is obtained from the condenser. V and liquid flow L V and remove it from C1. Then the liquid flow L VThe liquid stream L2 is sent to the evaporator E1 where it is heated to obtain the vapor stream V L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. Stream L3 is used as heating medium in heat exchanger H1 for preheating stream L1 and obtaining a correspondingly cooled stream L4.

[0264] Figure 5 is a schematic diagram of the method according to the invention, which comprises a two-step preheating of the liquid stream L1

[0265] according to Figure 5 , an aqueous liquid stream L1 containing at least one hexane-1,6-diamine substance (which contains at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a first heat exchanger H2, and the corresponding heated stream L1 is passed through a second heat exchanger H1, and the corresponding heated stream L1 is sent to the top section of a stripping column. At the top of the stripping column, a vapor stream V containing carbon dioxide is obtained and removed. The vapor stream V is used as a heating medium in the first heat exchanger H2 for the first preheating of the liquid stream L1, and a partially condensed stream V is obtained. L , then the partially condensed stream V L is sent to the condenser C1 and a vapor stream V is obtained from the condenser VL and liquid flow L VL At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed from the stripping column. The liquid stream L2 is sent to the evaporator E1 where it is heated to obtain a vapor stream V L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. Stream L3 is used as heating medium in the second heat exchanger H1 for preheating stream L1 and obtaining a correspondingly cooled stream L4.

[0266] Figure 6 is a schematic diagram of a method according to the invention comprising a two-step preheating of the liquid stream L1 and further comprising a reflux

[0267] according to Figure 6 , an aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a first heat exchanger H2, and the corresponding heated stream L1 is passed through a second heat exchanger H1 and sent to the top section of the stripping column. Figure 6In the embodiment of the present invention, the stripping column comprises an additional backwash section in the top section of the column, and the liquid stream L1 is introduced into the column between the stripping section and the backwash section. At the top of the stripping column, a vapor stream V containing carbon dioxide is obtained and removed. The vapor stream V is used as heating medium in the first heat exchanger H2 for the first preheating of the liquid stream L1, and a partially condensed stream V is obtained. L , then the partially condensed stream V L is sent to the condenser C1 and a vapor stream V is obtained from the condenser VL and liquid flow L VL and remove it from C1. The liquid stream L1 is then divided into two streams L VL1 and L VL2 , and the flow L VL1 The liquid stream L2 is sent to the evaporator E1 where it is heated to obtain a vapor stream V L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. Stream L3 is used as heating medium in the second heat exchanger H1 for preheating stream L1 and obtaining a correspondingly cooled stream L4.

[0268] Figure 7 is a schematic diagram of a process according to the invention comprising a two-step preheating of the liquid stream L1, further comprising reflux and overhead vapor compression

[0269] according to Figure 7 , an aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a first heat exchanger H2, and the corresponding heated stream L1 is passed through a second heat exchanger H1 and sent to the top section of the stripping column. Figure 6 In the embodiment of the present invention, the stripping column comprises an additional backwash section in the top section of the column, and the liquid stream L1 is introduced into the column between the stripping section and the backwash section. At the top of the stripping column, a vapor stream V containing carbon dioxide is obtained and removed. A portion V is separated from the top vapor stream V. K , while the remaining stream V is used as heating medium in the first heat exchanger H2 for the first preheating of the liquid stream L1 and obtaining a partially condensed stream V L , then the partially condensed stream V L is sent to the condenser C1 and a vapor stream V is obtained from the condenser VL and liquid flow L VL and remove it from C1. The liquid stream L1 is then divided into two streams L VL1 and LVL2 , and the flow L VL 1 is sent back to the top section of the stripping column. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed from the stripping column. The liquid stream L2 is sent to the evaporator E1 where it is heated to obtain a vapor stream V L2 And liquid stream L3. Make the stream V separated from the vapor stream V K Passes through compressor K1 and obtains compressed flow V K and used as heating medium to heat the stream L3 in the evaporator E1. The corresponding cooled stream V is then K Transfer to drum, from which the liquid flow V K (1) is sent to the top section of the stripping column above the backwash section, and from this tank the gaseous stream V K (g) and the vapor flow V obtained from condenser C1 VL Combine the stream V obtained from evaporator E1 L2 The feed is returned to the bottom section of the stripping column for heating purposes. Stream L3 is used as heating medium in the second heat exchanger H1 for preheating stream L1 and obtaining a correspondingly cooled stream L4.

[0270] Figure 8 is a schematic diagram of a method according to the invention, the method further comprising evaporation of stream L3

[0271] according to Figure 8 , an aqueous liquid stream L1 comprising at least one hexane-1,6-diamine species comprising at least one carbon dioxide derivative of hexane-1,6-diamine is passed to the top section of a stripping column. At the top of the stripping column, a vapor stream V comprising carbon dioxide is obtained and removed. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed and then passed to an evaporator E1 where L2 is heated to obtain a vapor stream V L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. The liquid stream L3 obtained from the evaporator E1 is passed through the evaporator E2 and a vapor stream V is obtained. L3 and liquid flow L L3 , where L L3 is depleted in carbon dioxide and is concentrated with respect to hexane-1,6-diamine. As heating medium for the evaporator E2, the vapor stream V obtained from the top of the stripping column is used.

[0272] Figure 9 is a schematic diagram of a method according to the invention, the method further comprising evaporation of stream L3 and preheating of stream L1

[0273] according to Figure 9 , an aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a heat exchanger H1, and the corresponding heated stream L1 is conveyed to the top section of a stripping column. At the top of the stripping column, a vapor stream V comprising carbon dioxide is obtained and removed. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed and then conveyed to an evaporator E1, where L2 is heated to obtain a vapor stream V L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. The liquid stream L3 obtained from the evaporator E1 is passed through the evaporator E2 and a vapor stream V is obtained. L3 and liquid flow L L3 , where L L3 is depleted in carbon dioxide and is concentrated relative to hexane-1,6-diamine. L3 is used as heating medium in the heat exchanger H1 for preheating the liquid stream L1 and obtaining a correspondingly cooled stream V L3H As heating medium for the evaporator E2 , the vapor stream V obtained from the top of the stripping column is used.

[0274] Figure 10 is a schematic diagram of a method according to the invention, the method further comprising evaporation of stream L3 and preheating of stream L1, further comprising condensation of the vapor stream

[0275] according to Figure 10 , an aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a heat exchanger H1, and the corresponding heated stream L1 is conveyed to the top section of a stripping column. At the top of the stripping column, a vapor stream V comprising carbon dioxide is obtained and removed. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed and then conveyed to an evaporator E1, where L2 is heated to obtain a vapor stream V L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. The liquid stream L3 obtained from the evaporator E1 is passed through the evaporator E2 and a vapor stream V is obtained. L3 and liquid flow L L3 , where L L3 is depleted in carbon dioxide and is concentrated relative to hexane-1,6-diamine. L3 is used as heating medium in the heat exchanger H1 for preheating the liquid stream L1 and obtaining a correspondingly cooled stream V L3HAs heating medium for evaporator E2, the vapor stream V obtained from the top of the stripping column is used. The cooled stream V obtained from evaporator E2 is then sent to condenser C1, from which the liquid stream L is obtained. V and vapor flow V V The cooled stream V obtained from the heat exchanger H1 is then L3H A liquid aqueous stream is obtained as condensate via a condenser C2.

[0276] Figure 11 is a schematic diagram of a process according to the invention, the process further comprising evaporation of stream L3 and preheating of stream L1, further comprising condensation of the vapor stream, and further comprising reflux

[0277] according to Figure 11 , an aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a heat exchanger H1 and the correspondingly heated stream L1 is conveyed to the top section of the stripping column. Figure 11 In the embodiment of the present invention, the stripping column comprises an additional backwash section in the top section of the column, and a liquid stream L1 is introduced into the column between the stripping section and the backwash section. At the top of the stripping column, a vapor stream V containing carbon dioxide is obtained and removed. At the bottom of the stripping column, a liquid aqueous stream L2 depleted in carbon dioxide is obtained and removed and then conveyed to an evaporator E1 where L2 is heated to obtain a vapor stream V. L2 and liquid stream L3. Then stream V L2 The feed is returned to the bottom section of the stripping column for heating purposes. The liquid stream L3 obtained from the evaporator E1 is passed through the evaporator E2 and a vapor stream V is obtained. L3 and liquid flow L L3 , where L L3 is depleted in carbon dioxide and is concentrated relative to hexane-1,6-diamine. L3 is used as heating medium in the heat exchanger H1 for preheating the liquid stream L1 and obtaining a correspondingly cooled stream V L3H As heating medium for evaporator E2, the vapor stream V obtained from the top of the stripping column is used. The cooled stream V obtained from evaporator E2 is then sent to condenser C1, from which the liquid stream L is obtained. V and vapor flow V V The cooled stream V obtained from the heat exchanger H1 is then L3H The liquid aqueous stream LV obtained from the condenser C1 is then divided into two streams L V1 and L V2 , and stream LV1 is sent as reflux back to the top section of the stripper above the stripper backwash section.

[0278] Figure 12 is a schematic diagram of the process according to the invention comprising a two-stage evaporation of the stream L1

[0279] according to Figure 12 The aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is conveyed to a heating device E H1 In the first evaporation device E1, the heating medium flow S 11 By heating device E H1 The steam flow V1 and the liquid flow L1 are obtained from the evaporation device E1. 11 , liquid flow L 11 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H1 Get the corresponding cooled flow S 12 Then the liquid flow L 11 Convey to the heating device E H2 The steam flow V1 obtained from the first evaporation device E1 is used as a heating medium to pass through the heating device E2. H2 , for the liquid flow L 11 Heating is performed. From the evaporation device E1, a vapor flow V2 (V) and a liquid flow L are obtained. 11 (L2), the liquid stream L2 is carbon dioxide-depleted and rich in hexane-1,6-diamine. H2 Get the corresponding cooled flow W L2 .

[0280] Figure 13 is a schematic diagram of a process according to the invention comprising a two-stage evaporation of the stream L1, further comprising condensing the vapor stream obtained from the downstream evaporation stage

[0281] according to Figure 13 The aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is conveyed to a heating device E H1 In the first evaporation device E1, the heating medium flow S 11 By heating device E H1 The steam flow V1 and the liquid flow L1 are obtained from the evaporation device E1. 11 , liquid flow L 11 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H1 Get the corresponding cooled flow S 12 Then the liquid flow L 11 Convey to the heating device EH2 The steam flow V1 obtained from the first evaporation device E1 is used as a heating medium to pass through the heating device E2. H2 , for the liquid flow L 11 Heating is performed. From the evaporation device E1, a vapor flow V2 (V) and a liquid flow L are obtained. 12 (L2), the liquid stream L2 is carbon dioxide-depleted and rich in hexane-1,6-diamine. H2 Get the corresponding cooled flow W L2 The vapor stream V2 (V) obtained from the evaporation device E2 is then sent to the condenser C1 from which the condensed liquid stream L is obtained. V and vapor flow V V .

[0282] Figure 14 is a schematic diagram of the method according to the invention comprising a three-stage evaporation of the stream L1

[0283] according to Figure 14 The aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is conveyed to a heating device E H1 In the first evaporation device E1, the heating medium flow S 11 By heating device E H1 The steam flow V1 and the liquid flow L1 are obtained from the evaporation device E1. 11 , liquid flow L 11 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H1 Get the corresponding cooled flow S 12 Then the liquid flow L 11 Convey to the heating device E H2 The steam flow V1 obtained from the first evaporation device E1 is used as a heating medium to pass through the heating device E2. H2 , for the liquid flow L 11 Heating is performed. From the evaporation device E2, a vapor flow V2 and a liquid flow L are obtained. 12 , liquid flow L 12 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H2 Get the corresponding cooled flow W L2 Then the liquid flow L 12 Convey to the heating device E H3 The steam flow V2 obtained from the second evaporation device E2 is used as a heating medium to pass through the heating device E3. H3 , for the liquid flow L 12From the evaporation device E3, a vapor flow V3 (V) and a liquid flow L are obtained. 13 (L2), the liquid stream L2 is carbon dioxide-depleted and rich in hexane-1,6-diamine. H3 Get the corresponding cooled flow W L3 .

[0284] Figure 15 is a schematic diagram of a process according to the invention comprising a three-stage evaporation of stream L1, further comprising condensing the vapor stream obtained from the downstream evaporation stage

[0285] according to Figure 14 The aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is conveyed to a heating device E H1 In the first evaporation device E1, the heating medium flow S 11 By heating device E H1 The steam flow V1 and the liquid flow L1 are obtained from the evaporation device E1. 11 , liquid flow L 11 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H1 Get the corresponding cooled flow S 12 Then the liquid flow L 11 Convey to the heating device E H2 The steam flow V1 obtained from the first evaporation device E1 is used as a heating medium to pass through the heating device E2. H2 , for the liquid flow L 11 Heating is performed. From the evaporation device E2, a vapor flow V2 and a liquid flow L are obtained. 12 , liquid flow L 12 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H2 The corresponding cooled flow W is obtained L2 Then the liquid flow L 12 Convey to the heating device E H3 The steam flow V2 obtained from the second evaporation device E2 is used as a heating medium to pass through the heating device E3. H3 , for the liquid flow L 12 From the evaporation device E3, a vapor flow V3 (V) and a liquid flow L are obtained. 13 (L2), the liquid stream L2 is carbon dioxide-depleted and rich in hexane-1,6-diamine. H3 Get the corresponding cooled flow W L3 The vapor stream V3 (V) obtained from the evaporation device E3 is then sent to the condenser C1 from which the condensed liquid stream L is obtained.V and vapor flow V V .

[0286] Figure 16 is a schematic diagram of a method according to the invention comprising a two-stage evaporation of stream L1, further comprising a preheating of stream L1

[0287] according to Figure 16 The aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a heat exchanger H1 and the corresponding heated liquid stream L1 is conveyed to a heating device E1 equipped with H1 In the first evaporation device E1, the heating medium flow S 11 By heating device E H1 The steam flow V1 and the liquid flow L1 are obtained from the evaporation device E1. 11 , liquid flow L 11 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H1 Get the corresponding cooled flow S 12 Then the liquid flow L 11 Convey to the heating device E H2 The steam flow V1 obtained from the first evaporation device E1 is used as a heating medium to pass through the heating device E2. H2 , for the liquid flow L 11 Heating is performed. From the evaporation device E1, a vapor flow V2 (V) and a liquid flow L are obtained. 11 (L2), the liquid stream L2 is carbon dioxide-depleted and rich in hexane-1,6-diamine. H2 Get the corresponding cooled flow W L2 The vapor stream V2 (V) obtained from the evaporation device E2 is used as heating medium in the heat exchanger H1 for preheating the liquid stream L1 and obtaining a correspondingly cooled stream V L .

[0288] Figure 17 is a schematic diagram of a method according to the invention comprising a three-stage evaporation of stream L1, further comprising a preheating of stream L1

[0289] according to Figure 17 The aqueous liquid stream L1 comprising at least one hexane-1,6-diamine substance (which comprises at least one carbon dioxide derivative of hexane-1,6-diamine) is passed through a heat exchanger H1 and the corresponding heated liquid stream L1 is conveyed to a heating device E1 equipped with H1 In the first evaporation device E1, the heating medium flow S 11 By heating device E H1The steam flow V1 and the liquid flow L1 are obtained from the evaporation device E1. 11 , liquid flow L 11 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H1 Get the corresponding cooled flow S 12 Then the liquid flow L 11 Convey to the heating device E H2 The steam flow V1 obtained from the first evaporation device E1 is used as a heating medium to pass through the heating device E2. H2 , for the liquid flow L 11 Heating is performed. From the evaporation device E2, a vapor flow V2 and a liquid flow L are obtained. 12 , liquid flow L 12 is depleted in carbon dioxide and enriched in hexane-1,6-diamine. H2 Get the corresponding cooled flow W L2 Then the liquid flow L 12 Convey to the heating device E H3 The steam flow V2 obtained from the second evaporation device E2 is used as a heating medium to pass through the heating device E3. H3 , for the liquid flow L 12 From the evaporation device E3, a vapor flow V3 (V) and a liquid flow L are obtained. 13 (L2), the liquid stream L2 is carbon dioxide-depleted and rich in hexane-1,6-diamine. H3 Get the corresponding cooled flow W L3 The vapor stream V3 (V) obtained from the evaporation device E3 is used as heating medium in the heat exchanger H1 for preheating the liquid stream L1 and a correspondingly cooled stream V is obtained. L .

[0290] Figure 18 is a representation of the results obtained from Example 2.1.

[0291] exist Figure 18 In the graph of , the temperature of the evaporator E1 is plotted on the x-axis and the heat energy (in kWh) per kg of free HMDA is plotted on the y-axis. The following curves are shown for the following percentages of HMDA:

[0292]

[0293] Figure 19 is a representation of the results obtained from Examples 2.2 and 2.3.

[0294] exist Figure 19In the graph of , the temperature of the evaporator E1 is plotted on the x-axis, while on the y-axis are plotted the thermal energy (in kWh) per kg of free HMDA (upper graph) and the amount of free HMDA obtained per kg of HMDA substance in L1 (lower graph). The following curves are shown, attributable to the following percentages of HMDA:

[0295]

[0296] Figure 20 is a representation of the results obtained from Example 2.4.

[0297] exist Figure 20 In the graph of , the temperature of the evaporator E1 is plotted on the x-axis, while on the y-axis are plotted the thermal energy (in kWh) per kg of free HMDA (upper graph) and the amount of free HMDA obtained per kg of HMDA substance in L1 (lower graph). The following curves are shown, attributable to the following percentages of HMDA:

[0298]

[0299] Figure 21 is a representation of the results obtained from Example 2.5.

[0300] exist Figure 21 In the graph of , the temperature of the evaporator E1 is plotted on the x-axis and the specific energy requirement (in kWh) per kg of free HMDA is plotted on the y-axis. The following curves are shown for the following percentages of HMDA:

[0301]

[0302] Examples

[0303] 1. Determination of the thermal stability of HMDA aqueous solutions

[0304] The thermal stability of two aqueous solutions, a 20 wt% HMDA solution without CO2 and a 20 wt% HMDA solution loaded with CO2, was determined via dynamic differential calorimetry (DSC). For the CO2-free solution, an exothermic decomposition reaction with an energy release of more than 70 J / g was observed at a temperature of 465°C. The CO2-loaded HMDA solution (20 wt% HMDA with a CO2 loading of 1.0 mol CO2 / mol HMDA) was less heat-resistant and, at a temperature of 200°C (onset temperature), an exothermic reaction with an energy release of 50 J / g was observed. It can be ruled out that the energy release observed at the onset temperature is due to the release of CO2, since CO2 release is an endothermic process. Therefore, it can be concluded that starting at a temperature of 200°C, CO2-loaded HMDA in aqueous solution is thermally unstable.

[0305] 2. Examples based on process simulation

[0306] Before the process simulation, a thermodynamic model was developed based on which the phase equilibrium (vapor-liquid equilibrium) of the system CO2–HMDA–H2O can be described. The following chemical reactions in the liquid phase were considered:

[0307] Proton self-migration of water:

[0308] Formation of bicarbonate:

[0309] Carbonate formation:

[0310] 1. Protonation of HMDA:

[0311] 2. Protonation of HMDA:

[0312] Monocarbamate formation:

[0313] Formation of biscarbamate:

[0314] Formation of zwitterions:

[0315] For all process simulations, it is assumed that all reactions are carried out quickly enough during stripping and can therefore be regarded as equilibrium reactions. The model is based on gas solubility measurements for temperatures of 30°C to 60°C taken from the literature (Mondal et al., Fluid Phase Equilibria [fluid phase equilibrium], 402 (2015), pp. 102-112), supplemented by gas solubility measurements performed by the inventors of the present invention at up to 160°C. In addition, the vapor-liquid equilibrium of the binary system H2O-HMDA is also considered to allow for the volatility of HMDA to be described in addition to the dissolved amount of CO2. In this context, literature data (Rousseau et al., AIChE Symp. Ser. [AIChE Symposium Series] (1989) 85 (271), pp. 73-78) are used. In order to describe the non-ideality-activity coefficient v in the liquid phase, the G of Pitzer as formulated by Edwards is used. E -Modell (Edwards et al., AIChE J. (1975) 21(29), pp. 248-259), and to describe the gas phase, the cubic equation of state according to Redlich-Kwong-Soave was used. On this basis, process simulations can be used to describe the separation of CO2 and the preparation of a CO2-free aqueous HMDA solution.

[0316] For all process simulations described below, the following liquid aqueous feed stream L1 was used: aqueous solution, 10 wt-%, based on CO 2 -free HMDA, having a temperature of 30° C., which was adjusted to a pH of 8.5 using CO 2 .

[0317] 2.1 Using a stripping tower to separate CO2

[0318] According to this example 2.1, use Figure 4 The stripping column of the configuration shown in separates the CO2 contained in the feed stream L1. The stripping gas used is a stripping vapor which is prepared in situ during the stripping, i.e. in the bottom section of the stripping column, part of the HDA aqueous solution is evaporated. Due to the high boiling point of HMDA, essentially only water is evaporated. At the top of the stripping column, the preheated stream L1 is conveyed into the column and passed through it countercurrently to the stripping vapor. The preheating of L1 is achieved by heat integration, according to which the hot CO2-depleted HMDA solution leaving E1 as stream L3 transfers heat in H1 to the cold HMDA stream L1. At the top of the column, a vapor stream V is obtained, which contains H2O, CO2 and traces of HMDA. This stream V is conveyed to the condenser C1, in which the H2O and HMDA are condensed out and discharged as stream L Vis recycled back to the column and CO2 is used as a gas (stream V V ) leaves C1. For simulation purposes, condenser C1 was operated at an outlet temperature of 45°C.

[0319] As far as the stripping column is concerned, a mass transfer-based model is used in the model to describe the stripping column, for which a two-inch packing (one inch = 2.54 cm) with a packing height of 10 m is used. The diameter of the column is designed to be 65% of the flooding point of the column. The pressure at the top of the column varies between 0.6 and 9 bar, which corresponds to an evaporator temperature of between 88°C and 175°C. The proportion of free HMDA relative to the amount of HMDA contained in L1 is specified to be between 50% and 97%; thus, using this stripping column, the yield of free HMDA can be significantly increased. In addition, it was found that as the temperature / pressure in the stripping column increases, less energy is required to obtain free HMDA. Thus, for example, for 97% of free HMDA, the optimal temperature of evaporator E1 was found to be at least, preferably greater than 150°C. In this context, reference is made to Figure 18 , which shows the results of this simulation.

[0320] 2.2 Using a stripping tower to separate CO2

[0321] According to this example 2.2, use Figure 5 The stripping column of the configuration shown in Figure 1 separates the CO₂ contained in the feed stream L1. Compared to the stripping column described in Example 2.1, this configuration represents a modification that allows the method's objective, namely, increasing the HMDA content by evaporating and stripping the CO₂, to be achieved. This modification primarily relates to the heat integration concept involved and the fact that the condensate obtained from condenser C1 is not recirculated back into the stripping column.

[0322] According to the present heat integration concept, the cold feed stream L1 is first brought to a higher temperature using a vapor stream V containing HO, CO2 and traces of HMDA. The heated stream L1 thus obtained is then brought to its final temperature in a second heating step using a hot stream L3 obtained from the evaporator E1, which is depleted in CO2 and contains free HMDA. Once it has entered the column, the stream L1 (which passes through the column countercurrently with the stripping steam) is subjected to evaporation, thereby producing a top stream V containing CO2, HO and traces of HMDA.

[0323] As far as the stripping column is concerned, a mass transfer-based model is used in the model to describe the stripping column, for which a two-inch packing (one inch = 2.54 cm) with a packing height of 10 m is used. The diameter of the column is designed to be 65% of the flooding point of the column. The pressure at the top of the column varies between 0.2 and 9 bar, which corresponds to an evaporator temperature between 65° C. and 178° C. The degree of evaporation is specified by the water content of the CO2-poor concentrated HMDA solution (stream L2). Values of 80 wt.-%, 70 wt.-% and 60 wt.-% water content of L2 are selected. Although the corresponding necessary energy input is higher than the energy input according to Example 2.4 (three-stage evaporation); however, a higher free HMDA yield is obtained. According to Example 2.4, a maximum of 88% free HMDA is obtained at a water content of 80 wt.-%, while according to this Example 2.2, 98% free HMDA is obtained at a water content of 80 wt.-%. As Figure 19 As shown in , as the pressure / temperature in the stripping column increases, the portion of HMDA that is vaporized increases and is removed with the condensate.

[0324] 2.3 Using a stripping tower to separate CO2

[0325] According to this example 2.3, the configuration according to example 2.2 is enhanced by a backwash section at the top of the stripping column; see corresponding Figure 6 In particular, above the feed point of the column L1, an additional packed bed was installed. For the modeling of the column, a packing height of 3.5 m was chosen, with the same 2-inch packing used in the other packing section. The condensate flow L VL Partial flow L VL1 Transfer to the backwash section and select a reflux ratio of 1:10.

[0326] According to this process configuration, the HMDA content in the condensate can be reduced, and thus the overall yield of free HMDA can be reduced. As for the configuration without backwash section according to Example 2.2, there is an optimal temperature range with respect to energy input and free HMDA yield. Figure 19 , where the results are shown.

[0327] 2.4 Separation of CO2 using multi-stage evaporation

[0328] According to this example 2.4, evaporation is performed using a three-stage evaporation including heat integration, such as Figure 17 According to this process configuration, only evaporator E1 needs to be powered by external energy (such as external steam (flow S 11)) is heated, while evaporators E2 and E3 are heated by streams V1 and V2, respectively. To this end, the temperature and pressure of evaporator E2 must be lower than those of E1, and the temperature and pressure of evaporator E3 must be lower than those of E2, respectively. In addition, feed stream L1 is preheated in heat exchanger H1 using stream V3 = V. A value of 10 K is specified as the driving temperature difference between the condenser and the evaporator. The temperature of evaporator E1 is set, and the temperatures of evaporators E2 and E3 are optimized so that the temperature of evaporator E1 is lower than that of E1 by S 11 The energy supplied from the outside is minimized. For evaporator E1, the temperature is varied from 110°C to 200°C, with the water content of the CO2-lean concentrated HMDA solution being specified as 60 wt-%, 70 wt-% and 80 wt-%.

[0329] The results are shown in Figure 20 The decisive parameter is the amount of HMDA present as free HMDA after the CO 2 separation. Other HMDA species such as protonated HMDA or carbamates cannot be extracted in the subsequent extraction stage, where only free HMDA can be extracted into the organic phase. Figure 20 As shown in , for a value of 80 wt.-% water, the energy input is 2 kWh / kg free HMDA; surprisingly, it was found that the yield of free HMDA was 88%. (In this context, it should be noted that for a corresponding one-stage evaporation, the energy input would be as high as 6.2 kWh / kg free HMDA at a yield of only 74%.

[0330] In general, it was found that at higher temperatures and at temperatures of at least 130°C, the specific energy requirement of E1 was minimized, and at temperatures of at least 190°C, a slight increase in the energy requirement was observed.

[0331] 2.5 Separation of CO2 using stripping and evaporation

[0332] According to another configuration of the method of the present invention (in Figure 11 ), combining the advantages of stripping and evaporation. In this process, the stripping column is primarily used to drive off the CO2, and in the downstream evaporation stage E2, which is operated at a reduced pressure compared to the upstream stripping column, the excess steam obtained at the top of the stripping column in V is used to additionally evaporate the water contained in L3. Figure 11 The preferred embodiment shown in FIG. 1 is to obtain the corresponding flow V L3 It is further used to preheat the feed stream L1.

[0333] Thus, this process configuration combines the advantages of separating CO2 in a stripping column with the advantages of concentrating the bottoms stream obtained from said column with respect to its free HMDA content. The results are shown in Figure 21 middle.

[0334] References:

[0335] US 2017 / 0369913 A1

Claims

1. A method for removing carbon dioxide from a liquid aqueous stream L1 comprising at least one hexane-1,6-diamine species, the at least one hexane-1,6-diamine species comprising at least one carbon dioxide derivative of hexane-1,6-diamine, the method comprising (i) providing a carbon dioxide loading capacity c L1 The liquid aqueous stream L1, where c L1 is defined as n L1 (CO2) / n L1 (HMDA), where n L1 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L1, and n L1 (HMDA) is the molar amount of the at least one hexane-1,6-diamine substance in L1, wherein 0.5≤c L1 ≤2.5, wherein the liquid aqueous stream L1 to be subjected to heating according to (ii) has a temperature T L1 <T according to (ii); (ii) heating the liquid aqueous stream L1 provided according to (i) to a temperature T≥90° C. at a pressure p≥0.5 bar (absolute) to obtain a vapor stream V comprising carbon dioxide and to obtain a vapor stream exhibiting a carbon dioxide loading c L2 The liquid aqueous stream L2, where c L2 is defined as n L2 (CO2) / n L2 (HMDA), where n L2 (CO2) is the molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine in L2, and n L2 (HMDA) is the molar amount of the at least one hexane-1,6-diamine species in L2, wherein c L2 ≤0.

1.

2. The method according to claim 1, wherein 80 to 100 mol-%, preferably 90 to 100 mol-%, more preferably 95 to 100 mol-% of the at least one carbon dioxide derivative of hexane-1,6-diamine consists of one or more of the following: hexamethylene-1,6-carbamate, hexamethylene-1,6-dicarbamate, hexamethylene-1,6-carbamate zwitterion, hexamethylene-1,6-carbonate, hexamethylene-1,6-bicarbonate, and hexamethylene-1,6-bis-bicarbonate; wherein preferably 90 to 100 mol-%, more preferably 95 to 100 mol-%, more preferably 98 to 100 mol-% of the at least one hexane-1,6-diamine species consists of the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base.

3. The method according to claim 1 or 2, wherein 0.6≤c L1 ≤2.0, preferably 0.7≤c L1 ≤1.

6.

4. The method according to any one of claims 1 to 3, wherein 90 to 100 wt.-%, preferably 95 to 100 wt.-%, more preferably 99 to 100 wt.-% of the liquid aqueous stream L1 provided according to (i) consists of water, the at least one carbon dioxide derivative of hexane-1,6-diamine and optionally hexane-1,6-diamine free base; wherein the liquid aqueous stream L1 provided according to (i) has a pH preferably in the range of 6 to 10, more preferably in the range of 7 to 9.5, more preferably in the range of 7.5 to 9 at a temperature of L1 of 25°C.

5. The method according to any one of claims 1 to 4, wherein 10°C ≤ T L1 <T, preferably 15°C ≤ T L1 <T, more preferably 20°C ≤ T L1 <T; Wherein the temperature T according to (ii) is preferably in the range of 90°C to 190°C, more preferably in the range of 100°C to 180°C, more preferably in the range of 110°C to 170°C.

6. The method according to any one of claims 1 to 5, wherein c L2 ≤0.08, preferably c L2 ≤0.06, more preferably c L2 ≤0.04, more preferably c L2 ≤0.

02.

7. The method according to any one of claims 1 to 6, wherein Step (ii) is performed in a stripping column using a stripping medium, wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 into the stripping column, and wherein (ii) comprises (ii.1) heating the liquid aqueous stream L1 provided according to (i) to a temperature T of at least 90° C. in the stripping column at a pressure p of at least 0.5 bar abs.; (ii.2) A vapor stream V is obtained at the top of the stripping column, the vapor stream V having a temperature T V and contains carbon dioxide, and said vapor stream V is removed from the top of the stripping column; (ii.3) The liquid aqueous stream L2 is obtained at the bottom of the stripping column, and the liquid aqueous stream has a temperature T L2 and contains hexane-1,6-diamine free base, and said liquid aqueous stream L2 is removed from the bottom of the stripping column; The method further comprises (iii.1) subjecting the liquid aqueous stream L2 obtained according to (ii.3) to evaporation in an evaporator E1, thereby obtaining a stream having a temperature T VL2 The water vapor flow V L2 and has temperature T L3 The aqueous liquid stream L3, wherein preferably T VL2 =T L3 ; (iii.2) the water vapor stream V obtained according to (iii.1) L2 Feed back into the bottom section of the stripping column; wherein the stripping medium preferably comprises steam, wherein more preferably 90 to 100 wt-%, more preferably 95 to 100 wt-%, more preferably 99 to 100 wt-% of the stripping medium consists of steam, and The steam is preferably obtained at least partially, more preferably completely, in situ in the stripping column by heating the liquid aqueous stream L1 to the temperature T in the stripping column.

8. The method of claim 7, further comprising (iii.3) passing the aqueous liquid stream L3 obtained according to (iii.1) through a heat exchanger H1 to obtain a liquid having a temperature T L4 The flow L4, where T L4 <T L3 ; (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed to the stripping column, it is passed through the heat exchanger H1 to obtain a stream having a temperature T L1 The liquid aqueous stream L1, where T L1 >T L10 ; According to (iii.4), ΔT H1 =T L10 –T L4 , and wherein preferably ΔT H1 ≤20K, more preferably ΔT H1 ≤10K, more preferably ΔT H1 ≤5K.

9. The method according to claim 7 or 8, wherein The vapor stream V obtained according to (ii.2) further comprises water in addition to carbon dioxide, the method further comprising (iv.1) subjecting the vapor stream V obtained according to (ii.2) to condensation in a condenser C1, thereby obtaining a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ; Wherein the method preferably further comprises (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column, with the reflux ratio preferably in the range of 0.01 :1 to 1 :1, more preferably in the range of 0.03:1 to 0.3:1, more preferably in the range of 0.05:1 to 0.2:

1.

10. The method according to claim 7 or 8, wherein The vapor stream V obtained according to (ii.2) further comprises water in addition to carbon dioxide, the method further comprising (iv.0) passing the vapor stream V obtained according to (ii.2) through a heat exchanger H2, thereby obtaining a temperature T HVL <T V a partially condensed stream VL; (iv.1) subjecting the stream VL obtained according to (iv.0) to condensation in a condenser C1, thereby obtaining a stream containing water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ; The method further comprises the step of causing the L100 Before the liquid aqueous stream L1 passes through the heat exchanger H1 according to (iii.4), it is passed through the heat exchanger H2 according to (iv.0) to obtain a liquid aqueous stream having the temperature T L10 The liquid aqueous stream L1, where T L10 >T L100 , where ΔT H2 =T L100 –T HVL , and wherein preferably ΔT H2 ≤20K, more preferably ΔT H1 ≤10K, more preferably ΔT H1 ≤5K.

11. The method of claim 10, further comprising after (iv.0) and before (iv.1): (iv.2) dividing the stream VL obtained according to (iv.0) into two streams VL1 and VL2, feeding stream VL1 back into the top section of the stripping column, and subjecting stream VL2 to condensation in the condenser C1 according to (iv.2) as stream VL according to (iv.1); The reflux ratio is preferably in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, and more preferably in the range of 0.05:1 to 0.2:

1.

12. The method of any one of claims 7 to 11, further comprising (v.1) will have temperature T VK and a vapor stream V comprising carbon dioxide and preferably water K Removed from the top of the stripping column, the vapor stream V K preferably having the same chemical composition as the vapor stream V; (v.2) subjecting the stream V removed from the top of the stripping column according to (v.1) to K By means of compressor K1, a temperature T CVK The compressed flow V K , where T CVK >T VK ; (v.3) Make the compressed flow V K As heating medium is passed through the evaporator E1 according to (iii.1), thereby obtaining a liquid phase V K (1) and optionally a vapor phase V K (g) Cooled compressed flow V K ; (v.4) The liquid phase V obtained according to (v.3) is preferably K (1) or a portion thereof is fed into the top section of the stripping column.

13. The method of claim 7, further comprising (iii.3) passing the vapor stream V obtained according to (ii.2) through the evaporator E2, thereby obtaining a temperature T EV <T V The flow V; (iii.4) subjecting the aqueous stream L3 obtained according to (iii.1) to evaporation in the evaporator E2 according to (iii.3) to obtain a stream having a temperature T VL3 The water vapor flow V L3 and has temperature T LL3 The aqueous liquid flow L L3 , where preferably T VL3 =T LL3 ; The method preferably further comprises (iii.5) the steam-containing stream V obtained according to (iii.4) L3 Through the heat exchanger H1, a temperature T VL3H The water vapor flow V L3H , where T VL3H <T VL3 ; (iii.4) In the case of a temperature T L10 Before the liquid aqueous stream L1 is fed to the stripping column, it is passed through the heat exchanger H1 to obtain a stream having a temperature T L1 The liquid aqueous stream L1, where T L1 >T L10 ; wherein the water vapor stream V obtained according to (iii.5) is preferably L3H It undergoes condensation in condenser C2, thereby obtaining a liquid aqueous stream.

14. The method of claim 13, wherein: The vapor stream V obtained according to (iii.3) further comprises water in addition to carbon dioxide, the method further comprising (iv.1) subjecting the vapor stream V obtained according to (iii.3) to condensation in a condenser C1, thereby obtaining a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V ; The method preferably further comprises (iv.2) The liquid flow L obtained according to (iv.1) V Split into two streams L V1 and L V2 , and the flow L V1 The feed is returned to the top section of the stripping column; The reflux ratio is preferably in the range of 0.01:1 to 1:1, more preferably in the range of 0.03:1 to 0.3:1, and more preferably in the range of 0.05:1 to 0.2:

1.

15. The method according to any one of claims 1 to 6, wherein Step (ii) is carried out in an evaporation unit comprising n evaporation devices E connected in series. j , j = 1 ... n, where n ≥ 2, where the evaporation equipment E j Including heating device E Hj , where the evaporation equipment E j+1 Arranged in the evaporation equipment E j downstream of , wherein providing the liquid aqueous stream L1 according to (i) comprises feeding the liquid aqueous stream L1 for evaporation into the evaporation equipment E1; where for j = 1…n, (ii) includes In the evaporation equipment E j Medium pressure p j The next will have been fed to the evaporation equipment E j The liquid water stream is heated to a temperature T j , thus obtaining the vapor flow V j , the vapor flow V j With temperature T Vj and contains carbon dioxide, and the vapor stream V j From the evaporation device E j Removed and obtain liquid aqueous stream L 1j , the liquid aqueous flow L 1j With temperature T L1j And showed carbon dioxide loading c L1j , where c L1j is defined as n L1j (CO2) / n L1j (HMDA), where n L1j (CO2) is L 1j The molar amount of carbon dioxide contained in the at least one carbon dioxide derivative of hexane-1,6-diamine, and n L1j (HMDA) is L 1j The molar amount of at least one hexane-1,6-diamine substance in the liquid aqueous stream L 1j From the evaporation device E j removed; and Will be from E j The liquid aqueous stream L removed from 1j Feed to the evaporation equipment E j+1 and make the vapor flow V Lj As heat source through the evaporation device E j+1 Heating device E Hj+1 , and the flow W Lj+1 From the heating device E Hj+1 Remove and where for j=n, (ii) includes In the evaporation equipment E n Medium pressure p n The next will have been fed to the evaporation equipment E n The liquid water stream is heated to a temperature T n , thus obtaining the vapor flow V n = V, the vapor flow V has a temperature T V and contains carbon dioxide, and the vapor stream V is passed from the evaporation device E n and obtain a liquid aqueous stream L 1n = L2, the liquid aqueous stream L2 has a temperature T L2 And showed carbon dioxide loading c L2 , and the liquid aqueous stream L2 is passed from the evaporation device E n Remove One of the parameter pairs (T j ;p j ) is a parameter pair (T; p) as defined in claim 1, wherein the temperature T ≥ 90°C and the pressure p ≥ 0.5 bar (absolute); Preferably wherein n=7; more preferably wherein n=6; more preferably wherein n=5, more preferably wherein n=4, more preferably wherein n=3 or n=2.

16. The method of claim 15, wherein: the parameter pair (T1; p1) being the parameter pair (T; p) as defined in claim 1, wherein the temperature T ≥ 90°C and the pressure p ≥ 0.5 bar (absolute); Wherein T is preferably in the range of 90°C to 190°C, more preferably in the range of 110°C to 190°C, and further preferably in the range of 130°C to 190°C.

17. The method according to claim 15 or 16, wherein For j=1…n-1, p j+1 <p j ;c L1j+1 <c L1j And T j+1 <T j ; and where for j=1…n-1, ΔT Ej+1 =T Vj –T L1j+1 Preferably in the range of 5K to 10K.

18. The method according to any one of claims 15 to 17, wherein The vapor stream V further comprises water in addition to carbon dioxide, and the method further comprises subjecting the vapor stream V to condensation in a condenser C1, thereby obtaining a vapor stream comprising water, lean in carbon dioxide and having a temperature T LV Liquid flow L V , and further obtain a steam stream V containing carbon dioxide and depleted in water V .

19. The method according to any one of claims 15 to 17, further comprising passing the vapor stream V obtained according to (ii.2) through a heat exchanger H1, thereby obtaining a vapor stream having a temperature T VL <T V of the optionally partially condensed stream VL, wherein the process further comprises subjecting the stream VL to a temperature T L10 The liquid aqueous stream L1 passes through the heat exchanger H1 to obtain a liquid having a temperature T L1 The liquid aqueous stream L1, where T L1 >T L10 .

20. The method according to any one of claims 1 to 19, wherein The liquid aqueous stream L1 is obtainable or obtained by a fermentation process, and wherein the stream L2 or a downstream stream obtained therefrom is subjected to extraction, wherein the downstream stream obtained from L2 is a stream L3 as defined in claim 7, a stream L4 as defined in claim 8, or a stream L as defined in claim 13. L3 .

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