A method and separation system for adsorption separation of high-purity cyclopentane

Abstract

This invention relates to a method and system for adsorption separation of high-purity cyclopentane. This separation method can obtain cyclopentane product with a purity ≥99.5% and 2,2-dimethylbutane byproduct with a purity ≥97.2%, comprising two parts: adsorption and regeneration. This patent utilizes a ZSM-22 molecular sieve with a TON framework structure, loaded with 0.85-2.6% Cr and 0.6-1.5% Ti by mass percentage to form 100-mesh Cr-Ti-ZSM-22 molecular sieve adsorbent spheres. The cyclopentane yield of this process can reach as high as 99.4%. This process is highly adaptable to raw materials and can handle a wide range of cyclopentane and 2,2-dimethylbutane contents, with 2,2-dimethylbutane content ranging from 5% to 30%. The method is simple to operate, the adsorbent is readily available and easily regenerated, making it suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to the separation technology of cyclopentane, and particularly to a method and separation system for adsorption separation of high-purity cyclopentane. Background Technology

[0002] Cyclopentane is an important organic chemical raw material for the production of refrigerants and foaming agents. Because it does not damage the ozone layer, it has largely replaced chlorofluorocarbons in the freezer, refrigerator, and refrigeration insulation industries, showing promising market prospects. China is the world's largest consumer, accounting for approximately 40-50%, followed by Europe and the United States.

[0003] Cyclopentane is widely found in the C5 fraction, a byproduct of reforming units and ethylene production processes in oil refining plants. Ethylene byproduct C5 can be separated into n-pentane, isopentane, and cyclopentane through catalytic hydrogenation and separation. The C5-depleted oil from reforming units contains large amounts of n-pentane, isopentane, and cyclopentane, which can be obtained through separation alone. However, 2,2-dimethylbutane significantly affects the purity of cyclopentane. Cyclopentane and 2,2-dimethylbutane have similar boiling points (at atmospheric pressure): cyclopentane is 49.25℃, and 2,2-dimethylbutane is 49.74℃, a difference of 0.49℃. They are not only near-boiling systems but also azeotropic systems with an azeotropic point of 49.4℃. Conventional distillation methods cannot yield high-purity cyclopentane; only azeotropic distillation or extractive distillation methods can be used.

[0004] US patents US4954224 and US5055162 employ extractive distillation to separate cyclopentane and 2,2-dimethylbutane, using N-methylpyrrolidone, cyclohexanol, or a mixture thereof as solvents. Chinese patent CN201510029414.1 discloses a method for extractive distillation to separate cyclopentane and 2,2-dimethylbutane, using a mixture of solvents, with N,N-dimethylformamide and / or N-formylmorpholine as the main solvent and at least one of 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, cyclopentanol, cyclohexanol, ethylene glycol, propylene glycol, methyl acetate, ethyl acetate, and phenol as the secondary solvent. Chinese patent CN202011014425.X discloses a method for extractive distillation of cyclopentane and 2,2-dimethylbutane using a partitioned column, with N,N-dimethylformamide as the solvent. Although the aforementioned patents all disclose the ability to produce cyclopentane with high purity, the solvent ratio reaches 8-12, resulting in excessively high unit consumption, and all of them have varying degrees of solvent loss. No industrial-scale equipment has been found. Summary of the Invention

[0005] The purpose of this invention is to provide a method and separation system for adsorption separation of high-purity cyclopentane, so as to solve the problems of high energy consumption, low separation efficiency and large solvent consumption in current cyclopentane separation.

[0006] To achieve the above objectives, this application employs the following technical solution:

[0007] A method for adsorption separation of high-purity cyclopentane includes the following steps:

[0008] S1. Preparation of molecular sieve adsorbents:

[0009] By impregnation, Cr-Ti-ZSM-22 adsorbent precursors are formed by loading 0.85-2.6% Cr and 0.6-1.5% Ti by mass percentage onto ZSM-22 molecular sieve with a TON framework structure. After calcination in air at 450-550℃ for 4-8 hours, 100-mesh molecular sieve adsorbent spheres are finally formed by rotating a rotary molding machine.

[0010] S2. Add the molecular sieve adsorbent microspheres prepared in step S1 to two groups of four adsorption columns.

[0011] S3. The material to be separated is introduced into the adsorption column from the feed port at the top of the adsorption column, and the separated 2,2-dimethylbutane flows out from the discharge port at the bottom of the adsorption column.

[0012] S4. When the molecular sieve adsorbent in the adsorption column is saturated, the regeneration process of the molecular sieve adsorbent is started to separate the molecular sieve adsorbent from the cyclopentane. The desorbed cyclopentane flows out from the discharge port at the top of the adsorption column.

[0013] Furthermore, the material to be separated is a mixture of cyclopentane and 2,2-dimethylbutane, wherein the mass percentage of 2,2-dimethylbutane is between 5% and 30%, and the remainder is cyclopentane.

[0014] By adjusting the operating parameters of the adsorption process, cyclopentane and 2,2-dimethylbutane are separated, ultimately yielding cyclopentane with a purity ≥99.5% and 2,2-dimethylbutane byproducts with a purity ≥97.2% (depending on the raw material conditions, if the impurity content is low, this content can be appropriately increased).

[0015] Furthermore, the material to be separated contains trace amounts of n-pentane and / or isopentane, and the content of n-pentane and / or isopentane in the material to be separated can affect the purity of cyclopentane and 2,2-dimethylbutane.

[0016] Furthermore, the process conditions for the adsorption column are: temperature 70-100℃, pressure 150-300KPa; the process conditions for the regeneration of the molecular sieve adsorbent are: temperature 100-130℃, pressure 80-100KPa, and regeneration / desorption time 8S-10min.

[0017] A separation system for adsorption and separation of high-purity cyclopentane, utilizing any of the above separation methods, includes an adsorption column filled with molecular sieve adsorbent, an inlet at the top of the adsorption column connected to a supply device for the material to be separated via a feed pipe, and a preheater installed on the feed pipe.

[0018] The first outlet at the bottom of the adsorption column is connected to the inlet of the first cooler through the first pipeline, and the outlet of the first cooler is connected to the inlet of the 2,2-dimethylbutane storage tank through the second pipeline.

[0019] The second outlet at the top of the adsorption column is connected to the inlet of the second cooler via a third pipeline, and the outlet of the second cooler is connected to the cyclopentane storage tank via a fourth pipeline; the inlet of the vacuum pump is connected to the fourth pipeline.

[0020] Furthermore, it also includes a steam pipeline connected to the adsorption column for the regeneration / desorption of the molecular sieve adsorbent.

[0021] Furthermore, the adsorption columns are in two or more sets, which can be switched and exchanged to achieve continuous separation.

[0022] Furthermore, the outlet temperature of the preheater is 50-100℃; the outlet temperatures of the first and second coolers are both 20-49℃.

[0023] The beneficial effects of this invention are:

[0024] 1. The Cr-Ti-ZSM-22 molecular sieve developed in this invention has good adsorption capacity for cyclopentane, high selectivity, and high cyclopentane recovery rate.

[0025] 2. Low-temperature operation allows for the separation of cyclopentane and 2,2-dimethylbutane without the need for steam or under low-pressure steam conditions.

[0026] 3. The overall process avoids the use of solvents, reducing the fixed investment in equipment.

[0027] 4. The purity of the cyclopentane product obtained by this process is ≥99.5%, and the purity of the cyclopentane product can be appropriately adjusted according to market conditions; the purity of the 2,2-dimethylbutane product is ≥97.2% (depending on the content of n-pentane and isopentane in the material to be separated).

[0028] 5. The process is highly adaptable to raw materials and can handle a wide range of cyclopentane and 2,2-dimethylbutane contents, with 2,2-dimethylbutane content ranging from 5% to 30%. Attached Figure Description

[0029] Figure 1 This is a schematic process flow diagram of the adsorption and separation of high-purity cyclopentane according to the present invention.

[0030] Symbol explanation:

[0031] C101A / B is an adsorption column; C102A / B is an adsorption column; V101 is a 2,2-dimethylbutane storage tank; V102 is a cyclopentane storage tank; E101 is the first cooler; E102 is the preheater; E103 is the second cooler. Detailed Implementation

[0032] The technical solutions of the present invention will be described in detail below through embodiments. The following embodiments are merely exemplary and can only be used to explain and illustrate the technical solutions of the present invention, and should not be construed as limiting the technical solutions of the present invention.

[0033] The process of this invention is as follows:

[0034] like Figure 1 As shown, the materials to be separated are 2,2-dimethylbutane and cyclopentane, with contents of 25% and 75% respectively (the content of 2,2-dimethylbutane can be between 5-30%). Other impurities are determined as needed (directly affecting the purity of 2,2-dimethylbutane and cyclopentane). After molecular sieve adsorption and regeneration processes, 2,2-dimethylbutane with a purity ≥98.6% is obtained from 2,2-dimethylbutane storage tank V101, and cyclopentane with a purity ≥99.5% is obtained from cyclopentane storage tank V102.

[0035] The specific steps are as follows:

[0036] 1. Molecular sieve adsorption:

[0037] The materials to be separated, 2,2-dimethylbutane and cyclopentane, with contents of approximately 25% and 75% respectively, are preheated by preheater E102 and enter from the upper part of adsorption columns C101A / B or C102A / B. They are then heated by steam I to the molecular sieve adsorption operating temperature. The upper discharge valve is closed, and after the cyclopentane is adsorbed by the Cr-Ti-ZSM-22 molecular sieve adsorbent, the lower material outlet valve of the adsorption column is opened. The 2,2-dimethylbutane product, after being removed from cyclopentane, is cooled by the first cooler E101 and stored in the 2,2-dimethylbutane storage tank V101.

[0038] 2. Molecular sieve regeneration:

[0039] After the Cr-Ti-ZSM-22 molecular sieve is saturated with adsorption, close the upper feed valve and lower discharge valve of C101A / B or C102A / B, open the upper discharge valve, and use steam II to heat the adsorption column to the molecular sieve regeneration operating temperature. Control the operating pressure through vacuum pump P101. After the desorbed cyclopentane stream is cooled by the second cooler E103, it is stored in the cyclopentane storage tank V102.

[0040] 3. The two adsorption columns, C101A / B and C102A / B, can be switched and used interchangeably.

[0041] The operating conditions are as follows:

[0042] 1. Molecular sieve adsorption:

[0043] The process operating conditions of the adsorption column are: 70-100℃, 150-300KPa(a); the outlet temperature of the preheater E102 is 50-100℃; the adsorption time is 8S-10min; and the outlet temperature of the first cooler E101 is 20-49℃.

[0044] 2. Molecular sieve regeneration:

[0045] Adsorption column process operating conditions: 100-130℃, 80-100KPa(a); Second cooler E103 stream outlet temperature: 20-49℃; Regeneration / desorption time: 8S-10min.

[0046] This invention discloses an adsorption separation method for high-purity cyclopentane, applicable to the separation of mixtures of cyclopentane and 2,2-dimethylbutane. It is particularly suitable for separating mixtures of cyclopentane and 2,2-dimethylbutane containing trace amounts of n-pentane and isopentane after removing light components such as n-pentane and isopentane, and heavy components such as C6 components from the system. The purification concentration of the cyclopentane product can be determined according to market conditions. This process can concentrate cyclopentane purity to over 99.5% and 2,2-dimethylbutane purity to over 97.2% (depending on the n-pentane and isopentane content in the materials to be separated). The cyclopentane yield can reach as high as 99.4%.

[0047] Adsorber operating conditions:

[0048] Normal operating conditions Adsorption and dehydration regeneration Upper pressure / kPa(a) 150-300 80-100 Lower pressure / kPa(a) 158-308 88-108 Upper temperature / °C 70-100 100-130 Lower part temperature / °C 70-100 100-130

[0049] Example 1

[0050] The specific composition of the mixture of cyclopentane and 2,2-dimethylbutane to be processed is as follows:

[0051] Serial Number Components content / % Remark 1 isopentane 0.3 2 n-Pentane 0.2 3 2,2-Dimethylbutane 25 4 cyclopentane 74.5

[0052] 1. Molecular sieve adsorption:

[0053] The material to be separated, containing 0.3% isopentane, 0.2% n-pentane, 25.0% 2,2-dimethylbutane, and 74.5% cyclopentane, is preheated by preheater E102 and enters from the upper part of adsorption columns C101A / B or C102A / B. It is then heated by steam I to the molecular sieve adsorption operating temperature. The upper discharge valve is closed, and after the cyclopentane is adsorbed by the Cr-Ti-ZSM-22 molecular sieve, the lower material outlet valve of the adsorption column is opened. The 2,2-dimethylbutane product, after being cooled by the first cooler E101, is stored in the 2,2-dimethylbutane storage tank V101.

[0054] 2. Molecular sieve regeneration:

[0055] After the Cr-Ti-ZSM-22 molecular sieve is saturated with adsorption, close the upper feed valve and lower discharge valve of C101A / B or C102A / B, open the upper discharge valve, and use steam II to heat the adsorption column to the molecular sieve regeneration operating temperature. Control the operating pressure through vacuum pump P101. After the desorbed cyclopentane stream is cooled by the second cooler E103, it is stored in the cyclopentane storage tank V102.

[0056] 3. The two adsorption columns, C101A / B and C102A / B, can be switched and used interchangeably.

[0057] The operating conditions are as follows:

[0058] 1. Molecular sieve adsorption:

[0059] The process operating conditions of the adsorption column are: 70℃, 150KPa(a); the outlet temperature of the preheater E102 stream is 50℃; the adsorption time is 5.5min; and the outlet temperature of the first cooler E101 stream is 25℃.

[0060] 2. Molecular sieve regeneration:

[0061] The process operating conditions of the adsorption column are: 100℃, 80KPa(a); the outlet temperature of the E103 stream from the second cooler is 25℃; the regeneration / desorption time is 5.5min.

[0062] After adsorption separation, the cyclopentane and 2,2-dimethylbutane products obtained are as follows:

[0063] Cyclopentane products:

[0064] Serial Number Components content / % Remark 1 isopentane 0.04 2 n-Pentane 0.02 3 2,2-Dimethylbutane 0.14 4 cyclopentane 99.8

[0065] 2,2-Dimethylbutane products:

[0066]

[0067]

[0068] Cyclopentane yield: 99.9%.

[0069] Example 2

[0070] The specific composition of the mixture of cyclopentane and 2,2-dimethylbutane to be processed is as follows:

[0071] Serial Number Components content / % Remark 1 isopentane 0.04 2 n-Pentane 0.05 3 2,2-Dimethylbutane 5 4 cyclopentane 94.91

[0072] 1. Molecular sieve adsorption:

[0073] The material to be separated, containing 0.04% isopentane, 0.05% n-pentane, 5.0% 2,2-dimethylbutane and 94.91% cyclopentane, is preheated by preheater E102 and enters from the upper part of adsorption column C101A / B or C102A / B. It is then heated by steam I to the molecular sieve adsorption operating temperature. The upper discharge valve is closed, and after the cyclopentane is adsorbed by Cr-Ti-ZSM-22 molecular sieve, the lower material outlet valve of the adsorption column is opened. The 2,2-dimethylbutane product, after being cooled by the first cooler E101, is stored in 2,2-dimethylbutane storage tank V101.

[0074] 2. Molecular sieve regeneration:

[0075] After the Cr-Ti-ZSM-22 molecular sieve is saturated with adsorption, close the upper feed valve and lower discharge valve of C101A / B or C102A / B, open the upper discharge valve, and use steam II to heat the adsorption column to the molecular sieve regeneration operating temperature. Control the operating pressure through vacuum pump P101. After the desorbed cyclopentane stream is cooled by the second cooler E103, it is stored in the cyclopentane V102 tank.

[0076] 3. The two adsorption columns, C101A / B and C102A / B, can be switched and used interchangeably.

[0077] The operating conditions are as follows:

[0078] 1. Molecular sieve adsorption:

[0079] The process operating conditions of the adsorption column are: 100℃, 300KPa(a); the outlet temperature of the preheater E102 stream is 90℃; the adsorption time is 10min; and the outlet temperature of the first cooler E101 stream is 35℃.

[0080] 2. Molecular sieve regeneration:

[0081] The process operating conditions of the adsorption column are: 130℃, 100KPa(a); the outlet temperature of the E103 stream from the second cooler is 35℃; the regeneration / desorption time is 10min.

[0082] After adsorption separation, the cyclopentane and 2,2-dimethylbutane products obtained are as follows:

[0083] Cyclopentane products:

[0084] Serial Number Components content / % Remark 1 isopentane 0.01 2 n-Pentane 0.01 3 2,2-Dimethylbutane 0.38 4 cyclopentane 99.6

[0085] 2,2-Dimethylbutane products:

[0086] Serial Number Components content / % Remark 1 isopentane 0.64 2 n-Pentane 0.85 3 2,2-Dimethylbutane 97.24 4 cyclopentane 1.28

[0087] Cyclopentane yield: 99.9%.

[0088] Example 3

[0089] The specific composition of the mixture of cyclopentane and 2,2-dimethylbutane to be processed is as follows:

[0090] Serial Number Components content / % Remark 1 isopentane 0.01 2 n-Pentane 0.01 3 2,2-Dimethylbutane 30 4 cyclopentane 69.98

[0091] 1. Molecular sieve adsorption:

[0092] The material to be separated, containing 0.04% isopentane, 0.05% n-pentane, 5% 2,2-dimethylbutane, and 94.91% cyclopentane, is preheated by preheater E102 and enters from the top of adsorption columns C101A / B or C102A / B. It is then heated by steam I to the molecular sieve adsorption operating temperature. The upper discharge valve is closed, and after the cyclopentane is adsorbed by the Cr-Ti-ZSM-22 molecular sieve, the lower material outlet valve of the adsorption column is opened. The 2,2-dimethylbutane product, after being cooled by the first cooler E101, is stored in the 2,2-dimethylbutane storage tank V101.

[0093] 2. Molecular sieve regeneration:

[0094] After the Cr-Ti-ZSM-22 molecular sieve is saturated with adsorption, close the upper feed valve and lower discharge valve of C101A / B or C102A / B, open the upper discharge valve, and use steam II to heat the adsorption column to the molecular sieve regeneration operating temperature. Control the operating pressure through vacuum pump P101. After the desorbed cyclopentane stream is cooled by the second cooler E103, it is stored in the cyclopentane storage tank V102.

[0095] 3. The two adsorption columns, C101A / B and C102A / B, can be switched and used interchangeably.

[0096] The operating conditions are as follows:

[0097] 1. Molecular sieve adsorption:

[0098] The process operating conditions of the adsorption column are: 85℃, 200KPa(a); the outlet temperature of the preheater E102 is 60℃; the adsorption time is 7min; and the outlet temperature of the first cooler E101 is 40℃.

[0099] 2. Molecular sieve regeneration:

[0100] The process operating conditions of the adsorption column were: 120℃, 95KPa(a); the outlet temperature of the E103 stream from the second cooler was 40℃; and the regeneration / desorption time was 7min.

[0101] After adsorption separation, the cyclopentane and 2,2-dimethylbutane products obtained are as follows:

[0102] Cyclopentane products:

[0103] Serial Number Components content / % Remark 1 isopentane 0.001 2 n-Pentane 0.001 3 2,2-Dimethylbutane 0.098 4 cyclopentane 99.9

[0104] 2,2-Dimethylbutane products:

[0105]

[0106]

[0107] Cyclopentane yield: 99.9%.

[0108] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for adsorption separation of high-purity cyclopentane, characterized in that, Includes the following steps: S1. Preparation of molecular sieve adsorbents: By impregnation, Cr-Ti-ZSM-22 adsorbent precursors are formed by loading 0.85-2.6% Cr and 0.6-1.5% Ti by mass percentage onto ZSM-22 molecular sieve with a TON framework structure. After calcination in air at 450-550℃ for 4-8 hours, 100-mesh molecular sieve adsorbent spheres are finally formed by rotating a rotary molding machine. S2. Add the molecular sieve adsorbent beads prepared in step S1 into the adsorption column; S3. The material to be separated is introduced into the adsorption column from the feed inlet at the top of the adsorption column, and the separated 2,2-dimethylbutane flows out from the discharge outlet at the bottom of the adsorption column. S4. When the molecular sieve adsorbent in the adsorption column is saturated, the regeneration process of the molecular sieve adsorbent is started to separate the molecular sieve adsorbent from the cyclopentane. The desorbed cyclopentane flows out from the discharge port at the top of the adsorption column. The process conditions for the adsorption column are: temperature 70-100℃, pressure 150-300KPa; the process conditions for the regeneration of the molecular sieve adsorbent are: temperature 100-130℃, pressure 80-100KPa, and regeneration / desorption time 8S-10min.

2. The method for adsorption separation of high-purity cyclopentane according to claim 1, characterized in that, The material to be separated is a mixture of cyclopentane and 2,2-dimethylbutane, wherein the mass percentage of 2,2-dimethylbutane is between 5% and 30%, and the remainder is cyclopentane.

3. The method for adsorption separation of high-purity cyclopentane according to claim 2, characterized in that, The material to be separated contains trace amounts of n-pentane and / or isopentane. The content of n-pentane and / or isopentane in the material to be separated can affect the purity of cyclopentane and 2,2-dimethylbutane.

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