Method and system for normalizing C6 alkane

Abstract

The invention relates to the technical field of normalizing, in particular to a C6 alkane normalizing method and system. The C6 alkane normalizing method comprises the following steps: A) carrying out low-temperature dechlorination treatment on isohexane after dehydration treatment; b) preheating the material obtained in the step A) by a second heat exchanger, preheating by a first heat exchanger, preheating by a reaction preheater, and carrying out a normalizing reaction in a normalizing reactor; c) cooling a product after the normalizing reaction through a second heat exchanger, and then carrying out gas-liquid separation; and D) feeding the liquid-phase material subjected to gas-liquid separation into a stabilizing tower to remove light components of C5 and below, feeding the material at the bottom of the stabilizing tower into an n-hexane tower to separate isohexane, and obtaining an n-hexane product at the bottom of the tower. The method provided by the invention can effectively convert isohexane into normal hexane.

Description

Technical Field

[0001] The present invention relates to the technical field of normalization, and in particular to a method and system for normalization of C6 alkanes. Background Art

[0002] Normalization is an important chemical reaction that can transform low-level chemicals into high-level substances. Its discovery is of great significance to the development of the field of chemistry, as it enables chemists to perform more sophisticated synthetic reactions. Normalization has been widely used in industrial production, and it can be used to make and transform a variety of useful organic substances. It is also often used in drug synthesis, thereby achieving universal and reasonable access to drugs.

[0003] At present, the mainstream normalization technology in industry is mainly concentrated in the C4 field, among which the typical one is the process technology of isobutane forming normal butane, but there is no report on the relevant process technology of normalization technology in the C5 / C6 field. After the epidemic, the domestic and foreign economies began to recover, and a series of polyolefin units of large domestic refineries and local refineries were gradually put into operation. The demand for environmentally friendly solvent n-hexane surged in the second half of 2023, and the phenomenon of market supply and demand is expected to reappear in the second half of 2024 to the first half of 2025. The process technology for the production of solvent n-hexane is mainly the separation process of raffinate oil / pyrolysis gasoline light hydrocarbon oil, but because the mass content of n-hexane in raffinate oil / pyrolysis gasoline light hydrocarbon oil is generally about 12%, and the mass content of isohexane component is about 20%. While obtaining the solvent n-hexane, a large amount of isohexane products will also be re-produced. Isohexane is mainly used as a common solvent in the cleaning industry, the preparation of gas chromatography calibration solutions, and as a gasoline additive to improve the combustion performance of gasoline. However, the isohexane market is relatively saturated, and excess isohexane is generally used for gasoline blending, which greatly affects and reduces the economic benefits of isohexane products. At the same time, with the gradual commissioning of polyolefin units in major refineries across the country in 2024, the environmentally friendly solvent n-hexane has great market potential. Therefore, how to convert isohexane into n-hexane has become the main problem to be solved. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method and system for normalization of C6 alkanes, which can effectively convert isohexane into normal-hexane.

[0006] The present invention provides a method for normalization of C6 alkanes, comprising the following steps:

[0007] A) subjecting isohexane to a dehydration treatment and then to a low-temperature dechlorination treatment;

[0008] B) preheating the material obtained in step A) through a second heat exchanger, then through a first heat exchanger, and then through a reaction preheater, and then entering a normalization reactor for a normalization reaction;

[0009] C) cooling the product after the normalization reaction through a second heat exchanger and then performing gas-liquid separation;

[0010] D) the liquid phase material after the gas-liquid separation enters a stabilization tower to remove light components of C5 and below, the material at the bottom of the stabilization tower enters a normal hexane tower to separate isohexane, and a normal hexane product is obtained at the bottom of the tower.

[0011] Preferably, in step A), the isohexane is high-purity isohexane, and the components of the high-purity isohexane include 2,2-dimethylbutane, cyclopentane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane and n-hexane; in the high-purity isohexane, the mass content of 2,2-dimethylbutane is 0.37%, the mass content of cyclopentane is 0.6%, the mass content of 2,3-dimethylbutane is 10.37%, the mass content of 2-methylpentane is 70.37%, the mass content of 3-methylpentane is 18.13%, and the mass content of n-hexane is 0.16%.

[0012] Preferably, in step A), the operating pressure of the dehydration treatment is controlled at 0.5-1.2 MPa, and the temperature is controlled at 50-120° C.;

[0013] The water content of the isohexane raw material after the dehydration treatment is ≤0.5ppm.

[0014] Preferably, in step A), the pressure of the low-temperature dechlorination treatment is controlled at 0.5-2.5 MPa and the temperature is controlled at 25-100° C.;

[0015] The material after the low-temperature dechlorination treatment satisfies the mass content of H2O ≤0.5ppm, the mass content of S ≤1.0ppm, the volume content of CO and CO2 ≤1.0ppm, the volume content of CO ≤10.5ppm, the mass content of olefins ≤10.0ppm, the mass content of Cl ≤0.1ppm, and the mass content of basic nitrogen ≤1.0ppm.

[0016] Preferably, step B) comprises:

[0017] The material obtained in step A) is preheated by the second heat exchanger, preheated by the first heat exchanger, and then preheated by the reaction preheater, and then enters the first normalization reactor for normalization reaction. The reaction product is cooled by the first heat exchanger, enters the second normalization reactor for normalization reaction, and then cooled by the second heat exchanger.

[0018] Preferably, in step B), the feed rate of the first normalization reactor is 3-6 t / h, the reaction temperature is 100-200°C, the pressure is 2.0-8.0 MPa, and the mass space velocity is 0.5-5.0 h -1 ;

[0019] The feed rate of the second normalization reactor is 3-6 t / h, the reaction temperature is 120-200°C, the pressure is 2.5-8.0 MPa, and the mass space velocity is 0.5-5.0 h -1 .

[0020] Preferably, in step C), the pressure of the gas-liquid separation is controlled at 0.5-3.0 MPa;

[0021] The hydrogen obtained by gas-liquid separation is recycled and enters the second heat exchanger again.

[0022] Preferably, in step D), the top pressure of the stabilization tower is controlled at 0.05-3 MPa, the top temperature is controlled at 50-200° C., and the bottom temperature is controlled at 50-300° C.;

[0023] The top temperature of the n-hexane tower is controlled at 50-150° C., the top pressure is controlled at 0-1.5 MPa, and the bottom temperature is controlled at 110-300° C.;

[0024] The isohexane component is separated from the top of the stabilization tower for reuse and enters the second heat exchanger again.

[0025] The present invention also provides a system for normalization of C6 alkanes, comprising:

[0026] A drying tower, wherein the drying tower is provided with an isohexane inlet;

[0027] a dechlorination tank connected to the isohexane outlet of the drying tower;

[0028] a second heat exchanger, wherein the isohexane inlet of the second heat exchanger is connected to the isohexane outlet of the dechlorination tank;

[0029] a first heat exchanger, wherein the isohexane inlet of the first heat exchanger is connected to the isohexane outlet of the second heat exchanger;

[0030] a reaction preheater connected to the isohexane outlet of the second heat exchanger;

[0031] A first normalization reactor connected to the isohexane outlet of the reaction preheater; a product outlet of the first normalization reactor is connected to a product inlet of the first heat exchanger;

[0032] A second normalization reactor connected to the product outlet of the first heat exchanger; the product outlet of the second normalization reactor is connected to the product inlet of the second heat exchanger;

[0033] A high-precipitation gas-liquid separation tank connected to the product outlet of the second heat exchanger;

[0034] A stabilization tower connected to the liquid material outlet of the high-resolution gas-liquid separation tank;

[0035] A n-hexane tower is connected to the bottom material outlet of the stabilization tower; and a n-hexane outlet is arranged at the bottom of the n-hexane tower.

[0036] Preferably, a first branch inlet is provided on the pipeline between the dechlorination tank and the second heat exchanger; the hydrogen outlet of the high-precision gas-liquid separation tank is connected to the first branch inlet;

[0037] A second branch inlet is arranged on the pipeline between the dechlorination tank and the second heat exchanger; and the isohexane outlet of the normal hexane tower is connected to the second branch inlet.

[0038] The present invention provides a method for normalization of C6 alkanes, comprising the following steps: A) performing a low-temperature dechlorination treatment on isohexane after dehydration treatment; B) preheating the material obtained in step A) through a second heat exchanger, preheating through a first heat exchanger, and then preheating through a reaction preheater, and then entering a normalization reactor for normalization reaction; C) cooling the product after the normalization reaction through a second heat exchanger, and then performing gas-liquid separation; D) entering a liquid phase material after the gas-liquid separation into a stabilization tower to remove light components of C5 and below, and the material at the bottom of the stabilization tower enters a normal hexane tower to separate isohexane, and a normal hexane product is obtained at the bottom of the tower. The method provided by the present invention can effectively convert isohexane into normal hexane. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The main principle diagram of the normalization reaction;

[0040] Figure 2 A system diagram for normalization of C6 alkanes is provided for one embodiment of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The present invention provides a method for normalization of C6 alkanes, comprising the following steps:

[0043] A) subjecting isohexane to a dehydration treatment and then to a low-temperature dechlorination treatment;

[0044] B) preheating the material obtained in step A) through a second heat exchanger, then through a first heat exchanger, and then through a reaction preheater, and then entering a normalization reactor for a normalization reaction;

[0045] C) cooling the product after the normalization reaction through a second heat exchanger and then performing gas-liquid separation;

[0046] D) the liquid phase material after the gas-liquid separation enters a stabilization tower to remove light components of C5 and below, the material at the bottom of the stabilization tower enters a normal hexane tower to separate isohexane, and a normal hexane product is obtained at the bottom of the tower.

[0047] Step A):

[0048] The isohexane raw material is dehydrated and then subjected to low-temperature dechlorination treatment.

[0049] In certain embodiments of the present invention, the isohexane is high-purity isohexane, and the components of the high-purity isohexane include 2,2-dimethylbutane, cyclopentane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane and normal hexane. In the high-purity isohexane, the mass content of 2,2-dimethylbutane is 0.37%, the mass content of cyclopentane is 0.6%, the mass content of 2,3-dimethylbutane is 10.37%, the mass content of 2-methylpentane is 70.37%, the mass content of 3-methylpentane is 18.13%, and the mass content of normal hexane is 0.16%. The water content (mass content) of the isohexane raw material is 30-40ppm.

[0050] The dehydration treatment is carried out in a drying tower. The operating pressure of the dehydration treatment (drying tower) is controlled at 0.5-1.2 MPa, such as 0.8 MPa; the temperature is controlled at 50-120° C., such as 80° C. The water content (mass content) of the isohexane raw material after the dehydration treatment is ≤0.5 ppm.

[0051] Low temperature dechlorination treatment is to treat HCl generated in the pretreatment of isohexane during hydrogenation reaction. In certain embodiments of the present invention, the low temperature dechlorination treatment is carried out in a dechlorination tank. The pressure of the low temperature dechlorination treatment (dechlorination tank) is controlled at 0.5-2.5 MPa and the temperature is controlled at 25-100°C.

[0052] In certain embodiments of the present invention, the material after the low-temperature dechlorination treatment satisfies the mass content of H2O ≤0.5ppm, the mass content of S ≤1.0ppm, the volume content of CO and CO2 ≤1.0ppm, the volume content of CO ≤10.5ppm, the mass content of olefins ≤10.0ppm, the mass content of Cl ≤0.1ppm, and the mass content of basic nitrogen ≤1.0ppm.

[0053] Step B):

[0054] The material obtained in step A) is preheated in the second heat exchanger, then preheated in the first heat exchanger, and then preheated in the reaction preheater before entering the normalization reactor for normalization reaction.

[0055] More specifically, the material obtained in step A) is preheated by the second heat exchanger, then preheated by the first heat exchanger, and then preheated by the reaction preheater, and then enters the first normalization reactor for normalization reaction. The reaction product is cooled by the first heat exchanger, then enters the second normalization reactor for normalization reaction, and then cooled by the second heat exchanger.

[0056] The material temperature after preheating in the second heat exchanger is 70-90°C, such as 85°C; the material temperature after preheating in the first heat exchanger is 90-110°C, such as 107°C; the material temperature after preheating in the reaction preheater is 110-135°C, such as 132°C.

[0057] The temperature of the material after cooling by the first heat exchanger is 110-140°C, for example, 116°C; the temperature of the material after cooling by the second heat exchanger is 60-110°C, for example, 75°C.

[0058] In certain embodiments of the present invention, the catalyst for the normalization reaction is ATIS-2L low-temperature catalyst produced by Axens.

[0059] ATIS-2L low-temperature catalyst is a chlorinated alumina-based catalyst containing a small amount of Pt. It is sensitive to impurities and requires chlorine supplementation, so the water content (mass content) of the isohexane feedstock needs to be controlled.

[0060] In certain embodiments of the present invention, the feed rate of the first normalization reactor is 3-6 t / h, the reaction temperature is 100-200°C, the pressure is 2.0-8.0 MPa, and the mass space velocity is 0.5-5.0 h -1 (Note: The mass space velocity is the ratio of the reactor feed amount to the catalyst loading amount, and the reactor feed includes fresh feed and recycled feed.) Specifically, the feed amount of the first normalization reactor is 4 t / h; the reaction temperature is 135°C, 145°C, 165°C, 180°C, 195°C; the pressure is 3.5 MPa; the mass space velocity is 1.13 h -1 .

[0061] In certain embodiments of the present invention, the feed rate of the second normalization reactor is 3-6 t / h, the reaction temperature is 120-200°C, the pressure is 2.5-8.0 MPa, and the mass space velocity is 0.5-5.0 h -1(Note: The mass space velocity is the ratio of the reactor feed amount to the catalyst loading amount, and the reactor feed includes fresh feed and recycled feed.) Specifically, the feed amount of the second normalization reactor is 4 t / h; the reaction temperature is 135°C, 145°C, 165°C, 180°C, 195°C; the pressure is 3.5 MPa; the mass space velocity is 1.13 h -1 .

[0062] The main principle of the normalization reaction is the normalization of 2,3-dimethylbutane and 2-methylpentane to n-hexane, and the cracking to light components. Figure 1 shown. Figure 1 This is the main principle diagram of the normalization reaction.

[0063] Normalization reaction is an endothermic reaction, so the raw materials need to be preheated and heated up, but normalization is a reversible reaction, and the reaction can often proceed to a near equilibrium conversion rate. Since the heat effect of the reaction is very small, the effect of temperature on the equilibrium composition is not significant, but low temperature operation is beneficial to reduce side reactions. Therefore, the reaction product should be appropriately cooled to achieve the purpose of inhibiting side reactions.

[0064] Step C):

[0065] The product after the normalization reaction is cooled by a second heat exchanger and then subjected to gas-liquid separation.

[0066] In certain embodiments of the present invention, the gas-liquid separation is performed in a high-precision gas-liquid separation tank, which separates the product after the normalization reaction from hydrogen, and the hydrogen is recycled.

[0067] The pressure of the gas-liquid separation (high-separation gas-liquid separation tank) is controlled at 0.5-3.0 MPa.

[0068] The gas-liquid separation obtains hydrogen and liquid phase materials. The hydrogen obtained by gas-liquid separation is recycled and enters the second heat exchanger again, is preheated by the second heat exchanger, is preheated by the first heat exchanger, and is preheated by the reaction preheater before entering the normalization reactor for normalization reaction, and the subsequent treatment is repeated.

[0069] Specifically, a first branch inlet is provided on the pipeline between the dechlorination tank and the second heat exchanger; the hydrogen outlet of the high-resolution gas-liquid separation tank is connected to the first branch inlet. The hydrogen separated by the high-resolution gas-liquid separation tank can be transported to the first branch inlet through a hydrogen circulation compressor.

[0070] In certain embodiments of the present invention, in the first normalization reactor, the circulation ratio of hydrogen is 2 to 10 (circulation ratio = (reactor feed - fresh feed) / (fresh feed)), such as 7.5. The hydrogen circulation amount is 4000 to 6000 Nm 3 / h.

[0071] Step D):

[0072] The liquid phase material after the gas-liquid separation enters a stabilization tower to remove light components of C5 and below through ordinary distillation, and the material at the bottom of the stabilization tower enters a normal hexane tower to separate isohexane, and a normal hexane product is obtained at the bottom of the tower.

[0073] In certain embodiments of the present invention, the liquid phase material after the gas-liquid separation can enter the stabilization tower through a feed pump.

[0074] In certain embodiments of the present invention, the top pressure of the stabilization tower is controlled at 0.05-3 MPa, such as 1.5 MPa; the top temperature is controlled at 50-200°C, such as 68°C; and the bottom temperature is controlled at 50-300°C, such as 110°C.

[0075] The material at the bottom of the stabilization tower enters the n-hexane tower to separate isohexane, and the n-hexane product is obtained at the bottom of the tower. The isohexane component is separated from the top of the tower for reuse and enters the second heat exchanger again. After being preheated by the second heat exchanger, it is preheated by the first heat exchanger and then preheated by the reaction preheater, and then enters the normalization reactor for normalization reaction, and the subsequent treatment is repeated.

[0076] Specifically, a second branch inlet is arranged on the pipeline between the dechlorination tank and the second heat exchanger; and the isohexane outlet of the normal hexane tower is connected to the second branch inlet.

[0077] In certain embodiments of the present invention, the top temperature of the n-hexane tower is controlled at 50-150°C, such as 72°C; the top pressure is controlled at 0-1.5MPa, such as 1MPa; and the bottom temperature is controlled at 110-300°C, such as 115°C.

[0078] The normalized product enters the stabilization tower to separate C5 and lower light components. The bottom material of the stabilization tower enters the n-hexane tower to separate isohexane and n-hexane. The isohexane obtained at the top of the tower is mixed with fresh feed and fed into the normalization reactor. Qualified n-hexane products are obtained at the bottom of the tower.

[0079] The present invention also provides a system for normalization of C6 alkanes, comprising:

[0080] A drying tower, wherein the drying tower is provided with an isohexane inlet;

[0081] a dechlorination tank connected to the isohexane outlet of the drying tower;

[0082] a second heat exchanger, wherein the isohexane inlet of the second heat exchanger is connected to the isohexane outlet of the dechlorination tank;

[0083] a first heat exchanger, wherein the isohexane inlet of the first heat exchanger is connected to the isohexane outlet of the second heat exchanger;

[0084] a reaction preheater connected to the isohexane outlet of the second heat exchanger;

[0085] A first normalization reactor connected to the isohexane outlet of the reaction preheater; a product outlet of the first normalization reactor is connected to a product inlet of the first heat exchanger;

[0086] A second normalization reactor connected to the product outlet of the first heat exchanger; the product outlet of the second normalization reactor is connected to the product inlet of the second heat exchanger;

[0087] A high-precipitation gas-liquid separation tank connected to the product outlet of the second heat exchanger;

[0088] A stabilization tower connected to the liquid material outlet of the high-resolution gas-liquid separation tank;

[0089] A n-hexane tower is connected to the bottom material outlet of the stabilization tower; and a n-hexane outlet is arranged at the bottom of the n-hexane tower.

[0090] Figure 2 A system diagram of normalization of C6 alkanes is provided for one embodiment of the present invention. In which, 1 is a drying tower, 2 is a dechlorination tank, 3 is a first heat exchanger, 4 is a second heat exchanger, 5 is a reaction preheater, 6 is a first normalization reactor, 7 is a second normalization reactor, 8 is a high-fraction gas-liquid separation tank, 9 is a hydrogen circulation compressor, 10 is a feed pump, 11 is a stabilization tower, and 12 is a normal-hexane tower.

[0091] In certain embodiments of the present invention, a first branch inlet is provided on the pipeline between the dechlorination tank and the second heat exchanger; the hydrogen outlet of the high-resolution gas-liquid separation tank is connected to the first branch inlet. A hydrogen circulation compressor is provided between the hydrogen outlet of the high-resolution gas-liquid separation tank and the first branch inlet.

[0092] In certain embodiments of the present invention, a feed pump is provided between the liquid phase material outlet of the high-fraction gas-liquid separation tank and the stabilization tower.

[0093] In certain embodiments of the present invention, a second branch inlet is provided on the pipeline between the dechlorination tank and the second heat exchanger; and the isohexane outlet of the n-hexane tower is connected to the second branch inlet.

[0094] The present invention has no particular limitation on the types of the above-mentioned devices, and all of them can be commonly available on the market.

[0095] In order to further illustrate the present invention, a method and system for normalization of C6 alkanes provided by the present invention are described in detail below in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0096] Example 1

[0097] Using the present invention Figure 2 system;

[0098] 1) High-purity isohexane is used as a raw material, wherein the mass content of 2,2-dimethylbutane is 0.37%, the mass content of cyclopentane is 0.6%, the mass content of 2,3-dimethylbutane is 10.37%, the mass content of 2-methylpentane is 70.37%, the mass content of 3-methylpentane is 18.13%, and the mass content of n-hexane is 0.16%. The water content (mass content) of the isohexane raw material is 35 ppm.

[0099] The isohexane raw material is dehydrated in a drying tower, the operating pressure of the drying tower is controlled at 0.8MPa, the temperature is controlled at 80°C, and the water content (mass content) of the isohexane raw material after the dehydration treatment is ≤0.5ppm; then, low-temperature dechlorination treatment is carried out in a dechlorination tank, the pressure of the dechlorination tank is controlled at 1.5MPa, and the temperature is controlled at 50°C.

[0100] The material after low-temperature dechlorination treatment satisfies the mass content of H2O ≤0.5ppm, the mass content of S ≤1.0ppm, the volume content of CO and CO2 ≤1.0ppm, the volume content of CO ≤10.5ppm, the mass content of olefins ≤10.0ppm, the mass content of Cl ≤0.1ppm, and the mass content of basic nitrogen ≤1.0ppm.

[0101] 2) The material after low-temperature dechlorination treatment is preheated to 85°C by the second heat exchanger, preheated to 107°C by the first heat exchanger, and then preheated to 132°C by the reaction preheater, and then enters the first normalization reactor for normalization reaction, and the reaction product is cooled to 116°C by the first heat exchanger, enters the second normalization reactor for normalization reaction, and then cooled to 75°C by the second heat exchanger. The catalyst for the normalization reaction is ATIS-2L low-temperature catalyst produced by Axens.

[0102] The feed rate of the first normalization reactor is 4 t / h, the reaction temperature is 135°C, the pressure is 3.5 MPa, and the mass space velocity is 1.13 h -1 , the circulation ratio of hydrogen is 7.5; the feed rate of the second normalization reactor is 4t / h, the reaction temperature is 135°C, the pressure is 3.5Mpa, and the mass space velocity is 1.13h -1 .

[0103] 3) The product after the normalization reaction is cooled by the second heat exchanger, and then gas-liquid separation is performed in a high-resolution gas-liquid separation tank. The pressure of the high-resolution gas-liquid separation tank is controlled at 2.0 MPa. The hydrogen obtained by gas-liquid separation is recycled and enters the second heat exchanger again. After being preheated by the second heat exchanger, it is preheated by the first heat exchanger, and then preheated by the reaction preheater, and then enters the first normalization reactor for normalization reaction, and the subsequent treatment is repeated.

[0104] 4) The liquid phase material after the gas-liquid separation enters the stabilization tower through the feed pump to remove light components of C5 and below, and the material at the bottom of the stabilization tower enters the normal hexane tower to separate isohexane, and the normal hexane product is obtained at the bottom of the tower; the isohexane component is separated from the top of the tower for reuse, and enters the second heat exchanger again, and after being preheated by the second heat exchanger, it is preheated by the first heat exchanger, and then preheated by the reaction preheater, it enters the first normalization reactor for normalization reaction, and repeats the subsequent treatment. The top pressure of the stabilization tower is controlled at 1.5MPa, the top temperature is controlled at 68°C, and the bottom temperature is controlled at 110°C. The top temperature of the normal hexane tower is controlled at 72°C, the top pressure is controlled at 1MPa, and the bottom temperature is controlled at 115°C.

[0105] The components of the n-hexane product were detected, and the results are shown in Table 1.

[0106] Table 1 Component test results of n-hexane products

[0107]

[0108]

[0109] Example 2

[0110] The difference from Example 1 is:

[0111] In step 2), the reaction temperature of the first normalization reactor is 145°C, and the reaction temperature of the second normalization reactor is 145°C.

[0112] The components of the n-hexane product were detected, and the results are shown in Table 2.

[0113] Table 2 Component test results of n-hexane products

[0114]

[0115] Example 3

[0116] The difference from Example 1 is:

[0117] In step 2), the reaction temperature of the first normalization reactor is 165°C, and the reaction temperature of the second normalization reactor is 165°C.

[0118] The components of the n-hexane product were tested, and the results are shown in Table 3.

[0119] Table 3 Component test results of n-hexane products

[0120] Component name Mass content% Butane 0.23 Pentane 1.35 2,2-Dimethylbutane 0.62 2,3-Dimethylbutane 1.19 2-Methylpentane 1.77 3-Methylpentane 16.2 n-Hexane 78.64 Methylcyclopentane 0.23 Cyclohexane 0 C7+ 0 total 100

[0121] Example 4

[0122] The difference from Example 1 is:

[0123] In step 2), the reaction temperature of the first normalization reactor is 180°C, and the reaction temperature of the second normalization reactor is 180°C.

[0124] The components of the n-hexane product were tested, and the results are shown in Table 4.

[0125] Table 4 Component test results of n-hexane products

[0126]

[0127]

[0128] Example 5

[0129] The difference from Example 1 is:

[0130] In step 2), the reaction temperature of the first normalization reactor is 195°C, and the reaction temperature of the second normalization reactor is 195°C.

[0131] The components of the n-hexane product were tested, and the results are shown in Table 5.

[0132] Table 5 Component test results of n-hexane products

[0133]

[0134]

[0135] Since the reaction of normalization of isohexane to generate normal hexane is an endothermic reaction, it can be seen from Examples 1 to 5 that under the reaction conditions of a reaction temperature of 135 to 165° C. and a reaction pressure of 3.5 MPa, the normalization conversion rate of isohexane increases with the increase of the reaction temperature. However, when the reaction temperature is 180 to 195° C., the normalization conversion rate gradually decreases with the increase of the reaction temperature. This is mainly because isohexane is prone to some side reactions such as cracking and olefin saturation at high temperatures, which reduces the isohexane conversion rate. Therefore, selecting a suitable temperature range and appropriately maintaining a high temperature is conducive to the normalization reaction of isohexane.

[0136] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for normalization of C6 alkanes, comprising the following steps: A) subjecting isohexane to a dehydration treatment and then to a low-temperature dechlorination treatment; B) preheating the material obtained in step A) through a second heat exchanger, then through a first heat exchanger, and then through a reaction preheater, and then entering a normalization reactor for a normalization reaction; C) cooling the product after the normalization reaction through a second heat exchanger and then performing gas-liquid separation; D) the liquid phase material after the gas-liquid separation enters a stabilization tower to remove light components of C5 and below, the material at the bottom of the stabilization tower enters a normal hexane tower to separate isohexane, and a normal hexane product is obtained at the bottom of the tower.

2. The method according to claim 1, characterized in that In step A), the isohexane is high-purity isohexane, and the components of the high-purity isohexane include 2,2-dimethylbutane, cyclopentane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane and n-hexane; in the high-purity isohexane, the mass content of 2,2-dimethylbutane is 0.37%, the mass content of cyclopentane is 0.6%, the mass content of 2,3-dimethylbutane is 10.37%, the mass content of 2-methylpentane is 70.37%, the mass content of 3-methylpentane is 18.13%, and the mass content of n-hexane is 0.16%.

3. The method according to claim 1, characterized in that In step A), the operating pressure of the dehydration treatment is controlled at 0.5-1.2 MPa and the temperature is controlled at 50-120° C.; The water content of the isohexane raw material after the dehydration treatment is ≤0.5ppm.

4. The method according to claim 1, characterized in that: In step A), the pressure of the low-temperature dechlorination treatment is controlled at 0.5-2.5 MPa and the temperature is controlled at 25-100° C.; The material after the low-temperature dechlorination treatment satisfies the mass content of H2O ≤0.5ppm, the mass content of S ≤1.0ppm, the volume content of CO and CO2 ≤1.0ppm, the volume content of CO ≤10.5ppm, the mass content of olefins ≤10.0ppm, the mass content of Cl ≤0.1ppm, and the mass content of basic nitrogen ≤1.0ppm.

5. The method according to claim 1, characterized in that Step B) comprises: The material obtained in step A) is preheated by the second heat exchanger, preheated by the first heat exchanger, and then preheated by the reaction preheater, and then enters the first normalization reactor for normalization reaction. The reaction product is cooled by the first heat exchanger, enters the second normalization reactor for normalization reaction, and then cooled by the second heat exchanger.

6. The method according to claim 5, characterized in that In step B), the feed rate of the first normalization reactor is 3-6 t / h, the reaction temperature is 100-200°C, the pressure is 2.0-8.0 MPa, and the mass space velocity is 0.5-5.0 h -1 ; The feed rate of the second normalization reactor is 3-6 t / h, the reaction temperature is 120-200°C, the pressure is 2.5-8.0 MPa, and the mass space velocity is 0.5-5.0 h -1 .

7. The method according to claim 5, characterized in that In step C), the pressure of the gas-liquid separation is controlled at 0.5-3.0 MPa; The hydrogen obtained by gas-liquid separation is recycled and enters the second heat exchanger again.

8. The method according to claim 5, characterized in that In step D), the top pressure of the stabilization tower is controlled at 0.05-3 MPa, the top temperature is controlled at 50-200° C., and the bottom temperature is controlled at 50-300° C.; The top temperature of the n-hexane tower is controlled at 50-150° C., the top pressure is controlled at 0-1.5 MPa, and the bottom temperature is controlled at 110-300° C.; The isohexane component is separated from the top of the stabilization tower for reuse and enters the second heat exchanger again.

9. A system for normalization of C6 alkanes, comprising: A drying tower, wherein the drying tower is provided with an isohexane inlet; a dechlorination tank connected to the isohexane outlet of the drying tower; a second heat exchanger, wherein the isohexane inlet of the second heat exchanger is connected to the isohexane outlet of the dechlorination tank; a first heat exchanger, wherein the isohexane inlet of the first heat exchanger is connected to the isohexane outlet of the second heat exchanger; a reaction preheater connected to the isohexane outlet of the second heat exchanger; A first normalization reactor connected to the isohexane outlet of the reaction preheater; a product outlet of the first normalization reactor is connected to a product inlet of the first heat exchanger; A second normalization reactor connected to the product outlet of the first heat exchanger; the product outlet of the second normalization reactor is connected to the product inlet of the second heat exchanger; A high-precipitation gas-liquid separation tank connected to the product outlet of the second heat exchanger; A stabilization tower connected to the liquid material outlet of the high-resolution gas-liquid separation tank; A n-hexane tower is connected to the bottom material outlet of the stabilization tower; and a n-hexane outlet is arranged at the bottom of the n-hexane tower.

10. The system according to claim 9, characterized in that A first branch inlet is arranged on the pipeline between the dechlorination tank and the second heat exchanger; the hydrogen outlet of the high-precision gas-liquid separation tank is connected to the first branch inlet; A second branch inlet is arranged on the pipeline between the dechlorination tank and the second heat exchanger; and the isohexane outlet of the normal hexane tower is connected to the second branch inlet.

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