A method for treating hexamethylene diisocyanate light components and a method for producing hexamethylene diisocyanate

Abstract

This invention discloses a method for processing the light component of hexamethylene diisocyanate (HDI), and a method for preparing HDI using this light component processing method. The method involves hydrolyzing and dehydrating the light component, followed by ammoniation and purification, ultimately converting the light component into hexamethylenediamine. Hexamethylenediamine can then be returned as a raw material to the synthesis of HDI. This invention features a simple process and a relatively singular product. By effectively processing the light component and converting it into a raw material for HDI production, it has high application value.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for treating light components of hexamethylene diisocyanate (HDI) and a method for preparing hexamethylene diisocyanate. By effectively treating the light components, the light components are converted into raw materials for producing HDI, which has high application value. BACKGROUND

[0002] HDI is a bulk aliphatic isocyanate, mainly used for preparing HDI biuret and HDI trimer, and is an important raw material for producing polyurethane coatings and polyurethane elastomers. The product has the advantages of non-yellowing, strong weather resistance, etc., and is widely used in the fields of aviation, automobile, building, plastic, etc. HDI is generated by the reaction of phosgene and hexamethylene diamine, and then qualified products are obtained through the processes of phosgene removal, light component removal, rectification, etc. The light components mainly include chlorinated products of hexamethylene diamine, monoisocyanate, chlorinated isocyanate, etc. Due to the complex composition of the light components, the production enterprises generally send them to qualified manufacturers for incineration and landfill treatment. The HDI light components are not effectively utilized, causing resource waste and increasing the cost of enterprises when they are treated as waste.

[0003] The existing patents mainly study the synthesis process of HDI, the treatment method of tail gas, and the product refining and purification. There are few reports on the comprehensive utilization of HDI light components.

[0004] EP0626368A1 describes a method for preparing and purifying isocyanate by phosgene method, and the remaining residue after distillation is discharged as dust-free particles, and is incinerated after grinding. Incineration of light components leads to resource waste and environmental pollution.

[0005] EP1113003A1 describes a method for preparing aliphatic diisocyanate, which distills the crude reaction mixture of phosgenation of aliphatic diamine, separates the aliphatic diisocyanate production stream and the aliphatic diisocyanate waste stream, dissolves the aliphatic diisocyanate waste stream in a supercritical fluid under supercritical conditions, and extracts the aliphatic diisocyanate components by extraction, flashing and precipitation. However, this patent does not utilize the light components such as monoisocyanate and chlorinated isocyanate in the waste stream.

[0006] CN100569743C describes a method for purifying isocyanate, which separates the crude isocyanate stream into four streams to form a medium-boiling stream, a high-boiling stream and a low-boiling stream of the required product, and the low-boiling stream mainly contains 6-chlorohexyl isocyanate and 1,6-dichlorohexane as main impurities. However, this patent does not further process the low-boiling stream.

[0007] CN110072845B describes a method for preparing isocyanate, carbonating the distillation residue or pre-concentrated liquid from which the isocyanate to be prepared is removed, realizing the recovery of higher molecular weight phosgenation products in the distillation residue, but this patent does not focus on the treatment process of the lower molecular weight light component residue.

[0008] CN115925580A describes a method for resource utilization of HDI distillation residue, carbonylating heavy components such as carbodiimide, uretdione, and urea carbonyl chloride, condensing the carbonylation product with formic acid to obtain a multi-component mixed product including biuret polyisocyanate. However, this patent does not treat the light component.

[0009] The present patent provides a treatment scheme for HDI light component, which is hydrolyzed and dehydrated, then ammoniated, and the product is relatively single, which can be used as HDI synthesis raw material after refining. The process flow is shorter, and is suitable for industrial treatment of HDI light component. The present patent also provides a preparation method of hexamethylene diisocyanate using the light component treatment method. SUMMARY

[0010] The present application aims to provide a treatment method for HDI light component, which solves the problem that the prior art does not provide a treatment method for HDI light component, and improves the utilization efficiency of HDI light component.

[0011] In order to achieve the above-mentioned purpose, the present application provides a treatment method for HDI light component, comprising:

[0012] Step (1): pressurized hydrolysis of HDI light component, and dehydration of the hydrolyzed material, with the dehydration kettle residue used for ammoniation.

[0013] Step (2): ammoniation of the dehydration kettle residue in step 1 at a certain temperature and pressure, and distillation of the ammoniated liquid to obtain product hexamethylene diamine.

[0014] In the step (1), the amount of water used for hydrolysis is 20%-50% of the total weight of the light component, preferably 25%-35%.

[0015] The pressure for pressurized hydrolysis in the step (1) is 0.1-3 MPa, preferably 0.5-1 MPa, the hydrolysis temperature is 150-250℃, preferably 160-200℃, and the hydrolysis time is 0.5-5h, preferably 2-3h.

[0016] The vacuum degree for dehydration of the hydrolysis liquid in the step (1) is 10-100 KPa, preferably 10-20 KPa.

[0017] In step (2), ammonia is used for ammoniation. The molar amount is calculated based on the content of each component. The molar ratio of ammonia to the residue in the dehydration vessel is 5:1-20:1, preferably 10:1-20:1. Furthermore, after the reaction is completed, excess ammonia is recovered and added to the ammoniation system.

[0018] In step (2), the ammoniation pressure is 0.5MPa-2MPa, preferably 0.8MPa-1.2MPa, the ammoniation temperature is 260℃-350℃, preferably 280℃-300℃, and the ammoniation residence time is 10min-60min, preferably 20min-30min.

[0019] Furthermore, in step (2), the ammoniation is carried out in the presence of a catalyst, which is selected from phosphate catalysts, alkaline earth metal oxides, and transition metal oxides, preferably from one or more of phosphate catalysts and alkaline earth metal oxides, and more preferably from phosphate catalysts. Furthermore, the amount of catalyst used, by weight percentage, is 5%-25% of the total weight remaining in the dehydration reactor, preferably 10%-15%.

[0020] Furthermore, the catalyst is selected from one or more of magnesium phosphate, calcium phosphate, aluminum phosphate, magnesium oxide, calcium oxide, barium oxide, iron oxide, manganese oxide, and copper oxide, preferably from one or more of magnesium phosphate, calcium phosphate, aluminum phosphate, magnesium oxide, calcium oxide, and barium oxide, and more preferably from one or more of magnesium phosphate, calcium phosphate, and aluminum phosphate.

[0021] The ammoniation step (2) is carried out in a reactor, which is a fixed-bed reactor.

[0022] In step (2), the distillation is a negative pressure distillation with a vacuum degree of 1KPa-20KPa, preferably 1KPa-5KPa, a distillation tray number of 10-30, preferably 15-20, and a reflux ratio of 3:1-5:1.

[0023] The light component, by weight, comprises: 15-25 parts of 1,6-dichlorohexane, 5-10 parts of 1-amino-6-chlorohexane, 20-30 parts of 6-chlorohexyl isocyanate, 35-40 parts of 1-amino-6-hexyl isocyanate, and 1-3 parts of hexamethylene diisocyanate.

[0024] Alternatively, the light component, by weight, comprises the following components: 15-25 parts of 1,6-dichlorohexane, 5-10 parts of 1-amino-6-chlorohexane, 20-30 parts of 6-chlorohexyl isocyanate, 35-40 parts of 1-amino-6-hexyl isocyanate, and 1-3 parts of hexamethylene diisocyanate.

[0025] The finished product hexamethylenediamine accounts for 50%-90% of the total molar amount of the light components, by molar percentage.

[0026] The present invention further provides a method for preparing hexamethylene diisocyanate, wherein the light component of hexamethylene diisocyanate is treated using the aforementioned method.

[0027] This invention also provides a method for preparing hexamethylene diisocyanate, using the hexamethylenediamine product obtained by the hexamethylene diisocyanate light component treatment method as a raw material. The method for preparing hexamethylene diisocyanate is the phosgene process. Attached Figure Description

[0028] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0029] Figure 1 This is a flowchart of a method for processing light components of HDI proposed in this invention. Detailed Implementation

[0030] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for processing light components of HDI.

[0031] "Light components" refer to components with lower boiling points. In the HDI preparation process, light components are mainly chlorinated products of hexamethylenediamine, monoisocyanates, chloroisocyanates, and other components with boiling points lower than HDI. During the removal of light components, in order to ensure the quality of the HDI product obtained from subsequent distillation, some HDI will be lost to the light components and discharged together during the separation process. In this invention, the light components of HDI are mainly composed of 1,6-dichlorohexane (Cl(CH2)6Cl), 1-amino-6-chlorohexane (NH2(CH2)6Cl), 6-chlorohexyl isocyanate (Cl(CH2)6NCO), 1-amino-6-hexyl isocyanate (NH2(CH2)6NCO), and hexamethylene diisocyanate (OCN(CH2)6NCO). The light components, by weight, include: 15-25 parts of 1,6-dichlorohexane, 5-10 parts of 1-amino-6-chlorohexane, 20-30 parts of 6-chlorohexyl isocyanate, 35-40 parts of 1-amino-6-hexyl isocyanate, and 1-3 parts of hexamethylene diisocyanate.

[0032] "Dehydration residue" refers to the material remaining after the hydrolyzed material undergoes the dehydration process, mainly consisting of hexamethylenediamine, 1-amino-6-chlorohexane, and 1,6-dichlorohexane. The molar amount of the dehydration residue is calculated as the sum of the molar amounts of all components.

[0033] For the method of the present invention, there are no particular limitations on the method for obtaining the light component of HDI, as long as the separation of HDI and the light component can be achieved. The preferred method for preparing the HDI is through the reaction of phosgene with hexamethylenediamine, such as, but not limited to, the continuous gas-phase synthesis of HDI from phosgene and hexamethylenediamine, the preparation of HDI by first forming a salt of hexamethylenediamine and then reacting it with phosgene, or the preparation of HDI by first reacting hexamethylenediamine with phosgene at low temperature and then phosgenating it at high temperature. The presence or absence of solvents in the preparation process and the method of preparing HDI, whether intermittent or continuous, are not limited.

[0034] Figure 1 This is a flowchart of a method for processing light components of HDI proposed in this invention, as shown below. Figure 1 As shown, the present invention provides a method for processing light components of HDI, comprising the following steps:

[0035] Step (1): The light component of HDI is subjected to pressurized hydrolysis, and the hydrolyzed material is dehydrated. The residue in the dehydration reactor is used for ammoniation.

[0036] Step (2): The residue from the dehydration reactor in Step 1 is ammonified under a certain temperature and pressure, and the ammonified liquid is distilled to obtain the product hexamethylenediamine.

[0037] In step (1), the amount of water used is 20%-50% of the weight of the light component, preferably 25%-35%, by weight percentage.

[0038] In step (1), the pressure of pressurized hydrolysis is 0.1MPa-3MPa, preferably 0.5MPa-1MPa, the hydrolysis temperature is 150℃-250℃, preferably 160℃-200℃, and the hydrolysis time is 0.5h-5h, preferably 2h-3h.

[0039] The reactions involved in the hydrolysis process include, but are not limited to, the following reaction formulas:

[0040] Cl(CH2)6NCO+H2O→Cl(CH2)6NH2+CO2

[0041] NH2(CH2)6NCO+H2O→NH2(CH2)6NH2+CO2

[0042] OCN(CH2)6NCO+H2O→NH2(CH2)6NH2+CO2

[0043] The isocyanate in the light component of HDI is converted into amino groups through a hydrolysis process, avoiding the formation of difficult-to-treat urea impurities by reacting with ammonia during ammoniation. By selecting appropriate hydrolysis pressure, temperature, and time, the complete hydrolysis of isocyanate is ensured while maintaining both high efficiency and economy of the reaction.

[0044] The vacuum degree of hydrolysate dehydration in step (1) is 10KPa-100KPa, preferably 10KPa-20KPa.

[0045] In step (2), ammonia is used for ammoniation. The inventors have found that using excess ammonia in the ammoniation process significantly improves the conversion efficiency, allowing the ammoniation reaction to proceed fully and efficiently, thereby increasing the yield of the finished hexamethylenediamine. This may be because excess ammonia helps to promote the forward reaction of the ammoniation reaction. To achieve better ammoniation results and improve the conversion rate, the molar ratio of ammonia to the residue in the dehydration reactor is 5:1-20:1, preferably 10:1-20:1. Preferably, after the reaction is completed, excess ammonia is recovered and fed into the ammoniation system to achieve the recycling of ammonia and save raw materials.

[0046] In step (2), the ammoniation pressure is 0.5MPa-2MPa, preferably 0.8MPa-1.2MPa, the ammoniation temperature is 260℃-350℃, preferably 280℃-300℃, and the ammoniation residence time is 10min-60min, preferably 20min-30min.

[0047] The reactions involved in the ammoniation process include, but are not limited to, the following reaction formulas:

[0048] Cl(CH2)6Cl + NH3 → NH2(CH2)6NH2

[0049] NH2(CH2)6Cl+NH3→NH2(CH2)6NH2

[0050] The ammoniation process converts the chlorinated products in the light components into hexamethylenediamine, resulting in a single product composition that is beneficial for subsequent applications. By selecting appropriate ammoniation pressure, temperature, time, and ammonia input, the complete ammoniation of the chlorinated products can be ensured while maintaining both high efficiency and economy in the reaction.

[0051] Preferably, the ammoniation process is carried out in the presence of a catalyst. The catalyst in the ammoniation reaction helps to promote the forward reaction, improves the efficiency of the ammoniation reaction, and thus increases the yield of the finished product, hexamethylenediamine. The catalyst is selected from one or more of phosphate catalysts, alkaline earth metal oxides, and transition metal oxides, preferably from one or more of phosphate catalysts and alkaline earth metal oxides, and more preferably from phosphate catalysts. The types of phosphate catalysts, alkaline earth metal oxides, and transition metal oxides are not particularly limited, as long as they do not adversely affect the purpose of the invention. Suitable phosphate catalysts include, but are not limited to, one or more of magnesium phosphate, calcium phosphate, and aluminum phosphate; suitable alkaline earth metal oxides include, but are not limited to, one or more of magnesium oxide, calcium oxide, and barium oxide; and suitable transition metal oxides include, but are not limited to, one or more of iron oxide, manganese oxide, and copper oxide. The amount of catalyst used is 5%-25% of the remaining weight in the dehydration reactor, preferably 10%-15%.

[0052] Preferably, in step (2), the ammoniation process is carried out using ammonia gas in the presence of a catalyst. Preferably, the molar ratio of ammonia gas to the residue in the dehydration reactor is 10:1-20:1, and the catalyst is one or more selected from iron oxide, manganese oxide, copper oxide, magnesium oxide, calcium oxide, barium oxide, magnesium phosphate, calcium phosphate, and aluminum phosphate; more preferably, in step (2), the molar ratio of ammonia gas to the residue in the dehydration reactor is 10:1-20:1, and the catalyst is one or more selected from magnesium oxide, calcium oxide, barium oxide, magnesium phosphate, calcium phosphate, and aluminum phosphate; most preferably, in step (2), the molar ratio of ammonia gas to the residue in the dehydration reactor is 10:1-20:1, and the catalyst is one or more selected from magnesium phosphate, calcium phosphate, and aluminum phosphate.

[0053] In step (2), ammoniation is carried out in a reactor, which is a fixed-bed reactor.

[0054] In step (2), the distillation is performed under negative pressure, with a vacuum degree of 1 kPa-20 kPa, preferably 1 kPa-5 kPa. The number of distillation trays is 10-30, preferably 15-20, and the reflux ratio is 3:1-5:1. The distillation yields hexamethylenediamine, improving its purity. Preferably, the purity is above 99.5%, and further preferably above 99.8%.

[0055] The light component, by weight, comprises: 15-25 parts of 1,6-dichlorohexane, 5-10 parts of 1-amino-6-chlorohexane, 20-30 parts of 6-chlorohexyl isocyanate, 35-40 parts of 1-amino-6-isocyanate hexyl ester, and 1-3 parts of hexamethylene diisocyanate. The light component is substantially free of hexamethylenediamine.

[0056] In the light component, 1-amino-6-hexyl isocyanate is hydrolyzed to hexamethylenediamine, hexamethylene diisocyanate is hydrolyzed to hexamethylenediamine, 6-chlorohexyl isocyanate is hydrolyzed to 1-amino-6-chlorohexane, 1-amino-6-chlorohexane is then aminated to hexamethylenediamine, and 1,6-dichlorohexane is aminated to hexamethylenediamine. The product composition is singular.

[0057] The finished product hexamethylenediamine accounts for 50%-90% of the molar amount of the light component, and the specific formula for calculating the yield is shown below:

[0058]

[0059] The molar amount of the light component is calculated as the sum of the molar amounts of all components.

[0060] The HDI light component processing method described in this invention converts the HDI light component into hexamethylenediamine, which can be used as a raw material for HDI production. The conversion efficiency is high, realizing the resource utilization of the light component and improving economic benefits. At the same time, it avoids the practice of incinerating or landfilling the light component as waste in the prior art, which is beneficial to environmental protection.

[0061] Preferably, the final product, hexamethylenediamine, is returned to the production process of hexamethylene diisocyanate. The production process of hexamethylene diisocyanate is preferably the phosgene process.

[0062] Compared with the prior art, the present invention has the following advantages:

[0063] (1) The light component of HDI is first hydrolyzed to convert the isocyanate into amino groups, so as to avoid the reaction of isocyanate with ammonia during the ammonification process to generate urea impurities that are difficult to treat.

[0064] (2) The light component is hydrolyzed and aminated, and the main product is hexamethylenediamine, which has a relatively simple composition and reduces the difficulty of post-processing.

[0065] (3) The process is short and the light components of HDI are utilized by resources, making it suitable for industrial production.

[0066] (4) By effectively treating the light components, the light components can be converted into raw materials for HDI production and can be returned to the synthesis reaction of HDI, saving raw materials and being economical and environmentally friendly.

[0067] The technical solution of the present invention will be further described below with reference to specific embodiments. The scope of protection of the present invention is not limited to the following embodiments; these examples are provided for illustrative purposes only and do not limit the present invention in any way.

[0068] The equipment used in all embodiments of the present invention is:

[0069] The dehydration kettle and distillation column are both standard equipment.

[0070] Solid bed reactor manufacturer: Tianjin Aozhan Chemical Technology Co., Ltd.

[0071] In all embodiments of this invention, the HDI light component is obtained from the phosgene process during HDI production, with approximately 3-5% light component produced per ton of HDI. The HDI light component in the embodiments has the same composition, including 21 parts of 1,6-dichlorohexane, 8 parts of 1-amino-6-chlorohexane, 27 parts of 6-chlorohexyl isocyanate, 41 parts of 1-amino-6-hexyl isocyanate, and 3 parts of hexamethylene diisocyanate. Based on 100 kg of light component, and considering the total molar amount of each component in the HDI light component, the molar amount of the HDI light component is 667 mol. According to the law of conservation of mass, the total molar amount of the material after hydrolysis and dehydration remains unchanged; the molar amount remaining in the dehydration vessel is 667 mol. The more thorough the hydrolysis, the lower the weight remaining in the dehydration vessel.

[0072] Example 1:

[0073] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 30 kg of water used. The hydrolysis reaction pressure was 1.0 MPa, the hydrolysis reaction temperature was 200 °C, and the hydrolysis time was 3 h. The hydrolysate was dehydrated under a vacuum of 20 kPa, yielding 88.1 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 13.22 kg of magnesium phosphate catalyst was added to the fixed bed, with the catalyst amount being 15% of the weight of the dehydrated residue. 10005 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 15:1. The ammonification reaction pressure was 1.0 MPa, the ammonification temperature was 280 °C, and the residence time was 30 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 2 kPa, and a reflux ratio of 3:1. A total of 68.3 kg of finished hexamethylenediamine was obtained, with a content of 99.81% as determined by analysis. The finished hexamethylenediamine accounted for 88.12% of the initial light component molar amount.

[0074] Example 2:

[0075] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 30 kg of water used. The hydrolysis reaction pressure was 1.0 MPa, the hydrolysis reaction temperature was 180 °C, and the hydrolysis time was 3 h. The hydrolysate was dehydrated under a vacuum of 100 kPa, yielding 92.1 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 18.42 kg of magnesium oxide catalyst was added to the fixed bed, with the catalyst amount being 20% ​​of the weight of the dehydrated residue. 6670 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 10:1. The ammonification reaction pressure was 0.5 MPa, the ammonification temperature was 280 °C, and the residence time was 30 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 5 kPa, and a reflux ratio of 3:1. A total of 53.5 kg of finished hexamethylenediamine was obtained, with a content of 99.78% as determined by analysis. The finished hexamethylenediamine accounted for 69.03% of the initial light component molar amount.

[0076] Example 3:

[0077] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 50 kg of water used. The hydrolysis reaction pressure was 3.0 MPa, the hydrolysis reaction temperature was 240 °C, and the hydrolysis time was 5 h. The hydrolysate was dehydrated under a vacuum of 100 kPa, yielding 91.2 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 13.68 kg of aluminum phosphate catalyst was added to the fixed bed, with the catalyst amount being 15% of the weight of the dehydrated residue. 13340 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 20:1. The ammonification reaction pressure was 1.5 MPa, the ammonification temperature was 330 °C, and the residence time was 50 min. The ammonified liquid was then distilled in a negative pressure distillation column with 30 trays, a distillation vacuum of 10 kPa, and a reflux ratio of 3:1. A total of 62.3 kg of finished hexamethylenediamine was obtained, with a content of 99.85% as determined by analysis. The finished hexamethylenediamine accounted for 80.38% of the initial light component molar amount.

[0078] Example 4:

[0079] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 20 kg of water used. The hydrolysis reaction pressure was 0.5 MPa, the hydrolysis reaction temperature was 200 °C, and the hydrolysis time was 2 h. The hydrolysate was dehydrated under a vacuum of 50 kPa to obtain 91.8 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 22.95 kg of iron oxide catalyst was added to the fixed bed, with the catalyst amount being 25% of the weight of the dehydrated residue. 10005 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 15:1. The ammonification reaction pressure was 1.0 MPa, the ammonification temperature was 260 °C, and the residence time was 60 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 15 kPa, and a reflux ratio of 3:1. A total of 46.8 kg of finished hexamethylenediamine was obtained, with a content of 99.73% as determined by analysis. The finished hexamethylenediamine accounted for 60.38% of the initial light component molar amount.

[0080] Example 5:

[0081] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 40 kg of water used. The hydrolysis reaction pressure was 2.5 MPa, the hydrolysis reaction temperature was 220 °C, and the hydrolysis time was 3.5 h. The hydrolysate was dehydrated under a vacuum of 30 kPa to obtain 91.6 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 4.58 kg of magnesium phosphate catalyst was added to the fixed bed, with the catalyst amount being 5% of the weight of the dehydrated residue. 3335 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 5:1. The ammonification reaction pressure was 0.5 MPa, the ammonification temperature was 270 °C, and the residence time was 40 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 5 kPa, and a reflux ratio of 3:1. A total of 42.7 kg of finished hexamethylenediamine was obtained, with a content of 99.88% as determined by analysis. The finished hexamethylenediamine accounted for 55.09% of the initial light component molar amount.

[0082] Example 6:

[0083] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 30 kg of water used. The hydrolysis reaction pressure was 3.0 MPa, the hydrolysis reaction temperature was 250 °C, and the hydrolysis time was 4 h. The hydrolysate was dehydrated under a vacuum of 100 kPa, yielding 89.3 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 13.40 kg of calcium phosphate catalyst was added to the fixed bed, with the catalyst amount being 15% of the weight of the dehydrated residue. 13340 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 20:1. The ammonification reaction pressure was 2.0 MPa, the ammonification temperature was 350 °C, and the residence time was 60 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 5 kPa, and a reflux ratio of 5:1. A total of 61.1 kg of finished hexamethylenediamine was obtained, with a content of 99.82% as determined by analysis. The finished hexamethylenediamine accounted for 78.83% of the initial light component molar amount.

[0084] Example 7:

[0085] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 30 kg of water used. The hydrolysis reaction pressure was 1.0 MPa, the hydrolysis reaction temperature was 200℃, and the hydrolysis time was 3 h. The hydrolysate was dehydrated under a vacuum of 20 kPa to obtain 88.3 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. The catalyst in the fixed bed was a composite catalyst of 4.415 kg magnesium phosphate and 8.83 kg manganese oxide, with magnesium phosphate accounting for 5% of the weight of the dehydrated residue, manganese oxide accounting for 10% of the weight of the dehydrated residue, and the total catalyst amount accounting for 15% of the weight of the dehydrated residue. 10005 mol of ammonia was introduced, with an ammonia:dehydrated residue molar ratio of 15:1, an ammonification reaction pressure of 1.0 MPa, an ammonification temperature of 280℃, and a residence time of 30 min. The ammoniated liquid was then distilled in a negative pressure distillation column with 15 trays, a vacuum of 2 kPa, and a reflux ratio of 3:1. A total of 48.6 kg of hexamethylenediamine was obtained, with a purity of 99.78%, representing 62.71% of the initial light component molar weight.

[0086] Example 8:

[0087] (1) 100 kg of HDI light components were subjected to pressurized hydrolysis, with 30 kg of water used. The hydrolysis reaction pressure was 1.0 MPa, the hydrolysis reaction temperature was 200℃, and the hydrolysis time was 3 h. The hydrolysate was dehydrated under a vacuum of 20 kPa, and the residue from the dehydration reactor was used for ammoniation. (2) The residue from the dehydration reactor of the hydrolysate in step (1) was ammonified, and ammonia gas and the residue from the dehydration reactor were simultaneously introduced into the ammoniation fixed-bed reactor. The catalyst in the fixed bed was a composite catalyst consisting of 4.42 kg of magnesium phosphate, 4.42 kg of magnesium oxide, and 4.42 kg of copper oxide, wherein the amount of magnesium phosphate was 5% of the weight of the residue from the dehydration reactor, the amount of magnesium oxide was 5% of the weight of the residue from the dehydration reactor, the amount of copper oxide was 5% of the weight of the residue from the dehydration reactor, and the total amount of catalyst was 15% of the weight of the residue from the dehydration reactor. 10005 mol of ammonia gas was introduced, with an ammonia-to-dehydration residue molar ratio of 15:1. The ammoniation reaction pressure was 1.0 MPa, the ammoniation temperature was 280℃, and the residence time was 30 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 2 kPa, and a reflux ratio of 3:1. A total of 55.8 kg of hexamethylenediamine was obtained, with a purity of 99.86%, representing 71.99% of the initial light component molar weight.

[0088] Example 9:

[0089] (1) 100 kg of HDI light component was hydrolyzed under pressure, with water amounting to 30 kg of the light component weight. The hydrolysis reaction pressure was 1.0 MPa, the hydrolysis reaction temperature was 200℃, and the hydrolysis time was 3 h. The hydrolysate was dehydrated under a vacuum of 20 kPa, yielding 88.3 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 13.25 kg of magnesium phosphate catalyst was added to the fixed bed, with the catalyst amount being 15% of the dehydrated residue weight. 3335 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 5:1. The ammonification reaction pressure was 1.0 MPa, the ammonification temperature was 280℃, and the residence time was 30 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 2 kPa, and a reflux ratio of 3:1. A total of 46.2 kg of finished hexamethylenediamine was obtained, with a content of 99.83% as determined by analysis. The finished hexamethylenediamine accounted for 59.61% of the initial light component molar amount.

[0090] Comparative Example 1:

[0091] (1) 100 kg of HDI light component was subjected to pressurized hydrolysis, with water amounting to 30 kg of the light component weight. The hydrolysis reaction pressure was 1.0 MPa, the hydrolysis reaction temperature was 200℃, and the hydrolysis time was 3 h. The hydrolysate was dehydrated under a vacuum of 20 kPa, yielding 88.4 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. There was no catalyst in the fixed bed, and 10005 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 15:1. The ammonification reaction pressure was 1.0 MPa, the ammonification temperature was 280℃, and the residence time was 30 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 2 kPa, and a reflux ratio of 3:1. A total of 25.6 kg of finished hexamethylenediamine was obtained, with a content of 99.76% as determined by analysis. The finished hexamethylenediamine accounted for 33.03% of the initial light component molar amount.

[0092] Comparative Example 2:

[0093] (1) 100 kg of HDI light component was hydrolyzed under pressure, with water amounting to 30 kg of the light component weight. The hydrolysis reaction pressure was 1.0 MPa, the hydrolysis reaction temperature was 200℃, and the hydrolysis time was 3 h. The hydrolysate was dehydrated under a vacuum of 20 kPa, yielding 88.2 kg of dehydrated residue. (2) The dehydrated residue from step (1) was ammonified, with ammonia and the dehydrated residue entering the ammonification fixed-bed reactor simultaneously. 13.23 kg of magnesium phosphate catalyst was added to the fixed bed, with the catalyst amount being 15% of the dehydrated residue weight. 1334 mol of ammonia was added, with an ammonia:dehydrated residue molar ratio of 2:1. The ammonification reaction pressure was 1.0 MPa, the ammonification temperature was 280℃, and the residence time was 30 min. The ammonified liquid was then distilled in a negative pressure distillation column with 15 trays, a distillation vacuum of 2 kPa, and a reflux ratio of 3:1. A total of 29.3 kg of finished hexamethylenediamine was obtained, with a content of 99.79% as determined by analysis. The finished hexamethylenediamine accounted for 37.80% of the initial light component molar amount.

[0094] Experimental results:

[0095] The experimental results are as follows:

[0096] Table 1 Experimental Results

[0097] Serial number Mass of hexanediamine / kg Purity / % Molar amount of the initial light component / % Example 1 68.3 99.81 88.12 Example 2 53.5 99.78 69.03 Example 3 62.3 99.85 80.38 Example 4 46.8 99.73 60.38 Example 5 42.7 99.88 55.09 Example 6 61.1 99.82 78.83 Example 7 48.6 99.78 62.71 Example 8 55.8 99.86 71.99 Example 9 46.2 99.83 59.61 Comparative Example 1 25.6 99.76 33.03 Comparative Example 2 29.3 99.79 37.80

[0098] Examples 1-9 yielded high-purity hexamethylenediamine with a purity exceeding 99.7% and high yield. Approximately 3-5% light components were produced per ton of HDI, and 42.7-68.3 kg of hexamethylenediamine was obtained from 100 kg of light components, with a yield exceeding 55.09%. Examples 1, 3, and 6 used phosphoric acid catalysts in their ammoniation processes, achieving the highest yields with an ammonia-to-dehydration residue molar ratio of 15:1-20:1.

[0099] Comparative Example 1, without the use of a catalyst, had a yield of only 33.03%. Examples 1-9, which used an ammoniation catalyst, saw a significant increase in yield. This demonstrates that using a catalyst in the ammoniation process can further improve conversion efficiency and yield more finished hexamethylenediamine.

[0100] Magnesium phosphate catalyst was added in Examples 1 and 7-8. Example 1 used only magnesium phosphate catalyst, Example 7 used a composite catalyst of magnesium phosphate and manganese oxide, and Example 8 used a composite catalyst of magnesium phosphate, magnesium oxide, and copper oxide. The yield of Example 1 was the highest, followed by Example 8, and the yield of Example 7 was relatively low. It can be seen that under the same experimental conditions, phosphate catalysts have the best catalytic effect, followed by alkaline earth metal oxide catalysts, and then transition metal oxide catalysts.

[0101] Table 2 Effect of catalyst dosage and ammonia input on yield

[0102]

[0103] Examples 1, 5, 9, and Comparative Example 2 all used magnesium phosphate catalyst. Comparative Example 2 had the lowest ammonia input, with an ammonia-to-dehydration reactor molar ratio of 2:1, and a yield of only 37.80%. Examples 5 and 9 had increased ammonia input compared to Comparative Example 2, with an ammonia-to-dehydration reactor molar ratio of 5:1, and yields of 55.09% and 59.61%, respectively. Example 9 had a slightly higher yield than Example 5 due to the addition of more catalyst, but the difference was not significant. Example 1 was the optimal example, with the highest ammonia and catalyst inputs, an ammonia-to-dehydration reactor molar ratio of 15:1, and the catalyst accounting for 15% of the remaining weight in the dehydration reactor. It also had the highest yield, reaching 88.12%. Therefore, the amount of ammonia input during ammoniation affects the yield; a higher ammonia input results in a higher yield. A good effect is achieved when the ammonia-to-dehydration reactor molar ratio is 5:1. However, a further improvement is achieved when the ammonia-to-dehydration reactor molar ratio reaches 15:1. This is because excess ammonia promotes the forward reaction of ammoniation, thereby increasing the ammoniation efficiency and further increasing the yield of the finished product, hexamethylenediamine. In addition, the amount of catalyst input during ammoniation also affects the yield; a higher catalyst input results in a higher yield because increasing the catalyst input also promotes the forward reaction of ammoniation. However, a comparison between Examples 5 and 9 shows that when the ammonia input is low, increasing the catalyst input has limited effect on improving the ammoniation efficiency. As shown in Example 1, when both the ammonia input and the magnesium phosphate catalyst input are high, an unexpectedly high yield is obtained. This may be because the high ammonia input and the high catalyst input have a synergistic effect, greatly improving the efficiency of the ammoniation reaction and thus obtaining more finished product, hexamethylenediamine.

[0104] The present invention provides a method for processing HDI light components, which converts HDI light components into hexamethylenediamine with high product purity and high conversion efficiency, enabling the resource utilization of HDI light components.

[0105] Those skilled in the art should note that the embodiments described in this invention are merely exemplary, and various other substitutions, changes, and improvements can be made within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is defined only by the claims.

Claims

1. A process for the treatment of hexamethylene diisocyanate light components, characterized in that It comprises the following steps: Step (1) pressurized hydrolysis of hexamethylene diisocyanate light component, after hydrolysis, the material is dehydrated, and the dehydration residue is used for amination; Step (2) amination of the dehydration residue in step (1), and rectification of the amination liquid to obtain hexamethylene diamine product; The hexamethylene diisocyanate light component mainly comprises 1,6-dichlorohexane, 1-amino-6-chlorohexane, 6-chlorohexyl isocyanate and 1-amino-6-isocyanate hexyl.

2. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The amount of water used in the hydrolysis in step (1) is 20%-50% of the total weight of the light component.

3. The method of treating hexamethylene diisocyanate light components according to claim 2, characterized in that, The amount of water used in the hydrolysis in step (1) is 25%-35% of the total weight of the light component.

4. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized by, The pressure of the pressurized hydrolysis in step (1) is 0.1-3 MPa, the hydrolysis temperature is 150-250℃, and the hydrolysis time is 0.5-5 h.

5. The method of treating hexamethylene diisocyanate light components according to claim 4, characterized in that, The pressure of the pressurized hydrolysis in step (1) is 0.5-1 MPa, the hydrolysis temperature is 160-200℃, and the hydrolysis time is 2-3 h.

6. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The vacuum degree of the dehydration of the hydrolysis liquid in step (1) is 10-100 KPa.

7. The method of treating hexamethylene diisocyanate light components according to claim 6, characterized in that, The vacuum degree of the dehydration of the hydrolysis liquid in step (1) is 10-20 KPa.

8. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized by, The amination in step (2) uses ammonia, and the molar ratio of ammonia to the dehydration residue is 5:1-20:1 according to the molar amount calculated based on the content of each component.

9. The method of treating hexamethylene diisocyanate light components according to claim 8, characterized in that, The amination in step (2) uses ammonia, and the molar ratio of ammonia to the dehydration residue is 10:1-20:1 according to the molar amount calculated based on the content of each component.

10. The method of treating hexamethylene diisocyanate light components according to claim 8, characterized in that, After the reaction is completed, the excess ammonia is recovered and fed into the amination system.

11. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The amination pressure in step (2) is 0.5-2 MPa, the amination temperature is 260-350℃, and the amination residence time is 10-60 min.

12. The method of treating hexamethylene diisocyanate light components according to claim 11, characterized in that, The amination pressure in step (2) is 0.8-1.2 MPa, the amination temperature is 280-300℃, and the amination residence time is 20-30 min.

13. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The amination in step (2) is carried out in the presence of a catalyst, and the catalyst is selected from one or more of phosphate catalysts, alkaline earth metal oxides and transition metal oxides.

14. The method of treating hexamethylene diisocyanate light components according to claim 13, characterized in that, The amination in step (2) is carried out in the presence of a catalyst, and the catalyst is selected from one or more of phosphate catalysts and alkaline earth metal oxides.

15. The method of treating hexamethylene diisocyanate light components according to claim 14, characterized in that, The amination in step (2) is carried out in the presence of a catalyst, and the catalyst is a phosphate catalyst.

16. The method of treating hexamethylene diisocyanate light components according to claim 13, characterized in that, The catalyst is selected from one or more of magnesium phosphate, calcium phosphate, aluminum phosphate, magnesium oxide, calcium oxide, barium oxide, iron oxide, manganese oxide and copper oxide.

17. The method of treating hexamethylene diisocyanate light components according to claim 16, characterized in that, The catalyst is selected from one or more of magnesium phosphate, calcium phosphate and aluminum phosphate.

18. The method of treating hexamethylene diisocyanate light components according to claim 17, characterized in that, The catalyst is selected from one or more of magnesium phosphate, calcium phosphate and aluminum phosphate.

19. The method of treating hexamethylene diisocyanate light components according to claim 13, characterized in that, The amount of the catalyst used is 5%-25% of the total weight of the dehydration residue.

20. The method of treating hexamethylene diisocyanate light components according to claim 19, characterized in that, The amount of the catalyst used is 10%-15% of the total weight of the dehydration residue.

21. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The amination in step (2) is carried out in a reactor, and the reactor is a fixed bed reactor.

22. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The rectification in step (2) is negative pressure rectification, the vacuum degree is 1-20 KPa, the number of rectification plates is 10-30, and the reflux ratio is 3:1-5:

1.

23. The method of treating hexamethylene diisocyanate light components according to claim 22, characterized in that, The rectification in step (2) is negative pressure rectification, the vacuum degree is 1-5 KPa, and the number of rectification plates is 15-20.

24. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The light component comprises, in parts by weight, 1,6-dichlorohexane 15-25 parts, 1-amino-6-chlorohexane 5-10 parts, 6-chlorohexyl isocyanate 20-30 parts, 1-amino-6-isocyanate hexane 35-40 parts, and hexamethylene diisocyanate 1-3 parts.

25. The method of treating hexamethylene diisocyanate light components according to claim 1, characterized in that, The molar amount of the finished product hexamethylene diamine accounts for 50%-90% of the total molar amount of the light component in percentage by mole.

26. A process for the preparation of hexamethylene diisocyanate, characterized in that, The hexamethylene diisocyanate light component is treated by any one of the methods according to claims 1-25, and the hexamethylene diamine product obtained by the hexamethylene diisocyanate light component treatment method is used as a raw material.

27. The method of claim 26, wherein the hexamethylene diisocyanate is prepared by The preparation method of the hexamethylene diisocyanate is a phosgene method.

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