Method and apparatus for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from a non-azeotropic composition.

Abstract

This application provides a method for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from a non-azeotropic composition, wherein the non-azeotropic composition is a non-azeotropic composition of tert-amyl alcohol, benzyl alcohol, and 1,1,2,2,3,3,4-heptafluorocyclopentane. In this method, tert-amyl alcohol undergoes a dehydration reaction under the action of a catalyst, and the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is obtained by distillation. The 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is then dehydrated using a dehydrating agent to obtain the recovered 1,1,2,2,3,3,4-heptafluorocyclopentane. The catalyst comprises a main catalyst and a coating layer, the coating layer having a porous structure and coating the main catalyst. The catalyst does not contact the benzyl alcohol. The catalytic reaction component of this application avoids direct contact between the catalyst and the high-boiling-point benzyl alcohol, preventing high temperatures from causing catalyst structural damage or other chemical reactions.

Description

Technical Field

[0001] This application belongs to the field of fine chemical purification and separation, and in particular relates to a method and apparatus for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from a non-azeotropic composition. Background Technology

[0002] Currently, the most commonly used organic solvents in semiconductor cleaning are hydrofluorocarbons. Among them, 1,1,2,2,3,3,4-heptafluorocyclopentane has an ODP value of 0 and a GWP of [missing information - likely a value]. 100 With a value of 195, an atmospheric lifetime of 2.8 years, and a boiling point of 82.5℃, its greenhouse effect is far less than that of chain hydrofluorocarbons. Compared with existing hydrofluoroether cleaning agents on the market, it has a higher boiling point and is non-flammable, making it a more environmentally friendly hydrofluorocarbon cleaning agent that can reduce environmental impact.

[0003] 1,1,2,2,3,3,4-Hepanocyclopentane is an environmentally friendly cyclic hydrofluorocarbon and one of the representatives of fourth-generation cleaning agents. Due to its good compatibility with a variety of solvents, it can be used as a key component in the formulation of various azeotropic and non-azeotropic cleaning agents. It has excellent cleaning effects on cutting oils, stamping oils, fluxes, fluorinated oils, epoxy resins, silicone oils, etc. used in the production processes of machinery manufacturing, semiconductor material processing, and medical devices.

[0004] A non-azeotropic fluorinated cleaning agent can be obtained by mixing 1,1,2,2,3,3,4-heptafluorocyclopentane, benzyl alcohol, and tert-amyl alcohol in a ratio of 60%, 35%, and 5%, respectively. 1,1,2,2,3,3,4-heptafluorocyclopentane and tert-amyl alcohol form a binary azeotrope (boiling point 82℃). In practical use, the binary azeotrope removes oil and other contaminants from the substrate surface and then dissolves them in benzyl alcohol, thus achieving the purpose of removing pollutants. After prolonged use, the content of each component in the cleaning agent changes, leading to a decrease in cleaning effectiveness. However, due to the existence of the binary azeotrope, it is difficult to separate and recover 1,1,2,2,3,3,4-heptafluorocyclopentane from the used cleaning agent using conventional methods.

[0005] The intramolecular dehydration reaction of tert-amyl alcohol under the action of an acidic catalyst can break the binary azeotropic system and achieve the separation of various components in the cleaning agent. However, due to the high boiling point temperature (205℃) of benzyl alcohol and the condensation reaction that occurs under the action of acidic substances, common solid acid catalysts or liquid acid catalysts such as sulfuric acid and phosphoric acid cannot be directly used in this system. Therefore, there are few reports on the recovery of the key component 1,1,2,2,3,3,4-heptafluorocyclopentane in this non-azeotropic cleaning agent. Summary of the Invention

[0006] The purpose of this application is to provide a method for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from a used non-azeotropic composition. To address the problems of existing technologies, this application employs catalytic reactive distillation, whereby tert-amyl alcohol in the composition undergoes a dehydration reaction under certain conditions. The reaction process is coupled with the distillation operation to increase the reaction rate, enhance the relative volatility between components, and disrupt the original azeotropic system, thereby achieving the recovery of 1,1,2,2,3,3,4-heptafluorocyclopentane. This apparatus and method have the advantages of simple operation, high separation efficiency, high product purity, and long catalyst lifespan.

[0007] This application provides a method for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from an azeotropic composition.

[0008] The technical solution is as follows:

[0009] 1. A method for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from a non-azeotropic composition, wherein the non-azeotropic composition is a non-azeotropic composition of tert-amyl alcohol, benzyl alcohol, and 1,1,2,2,3,3,4-heptafluorocyclopentane, wherein,

[0010] The non-azeotropic composition undergoes a dehydration reaction of tert-amyl alcohol under the action of a catalyst, and the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is obtained by distillation.

[0011] The 1,1,2,2,3,3,4-heptafluorocyclopentane fraction was dehydrated by a dehydrating agent to obtain a 1,1,2,2,3,3,4-heptafluorocyclopentane recovery product.

[0012] The catalyst includes a main catalyst and a coating layer, wherein the coating layer has a porous structure and encapsulates the main catalyst;

[0013] The catalyst does not come into contact with the benzyl alcohol.

[0014] Furthermore, the catalyst is 0.01-0.5 parts by weight, compared to 1 part by weight of the azeotropic composition.

[0015] Furthermore, the minimum pore size of the porous structure of the coating layer is greater than the maximum pore size of the main catalyst.

[0016] Furthermore, the main catalyst is selected from one or more of the following: type A molecular sieve, type Y molecular sieve, type X molecular sieve, HZSM-5 molecular sieve, and strong acid cation exchange resin.

[0017] Preferably,

[0018] The strong acid cation exchange resin is selected from one or more of NKC-9, 001*7, D001, and D75.

[0019] Furthermore, the material of the wrapping layer is polyurethane, nylon filament, or polytetrafluoroethylene.

[0020] Furthermore, in the non-azeotropic composition, the mass ratio of 1,1,2,2,3,3,4-heptafluorocyclopentane, benzyl alcohol, and tert-amyl alcohol is 62:35:3.

[0021] Furthermore, the acidic substances in the 1,1,2,2,3,3,4-heptafluorocyclopentane recoverable are removed by an acid-removing agent to obtain the acid-removed 1,1,2,2,3,3,4-heptafluorocyclopentane recoverable.

[0022] This application provides a reactive distillation column for distillation, including a column body, wherein a catalytic reaction unit and random packing are arranged sequentially from the feed inlet to the discharge outlet in the column body;

[0023] The catalyst is provided within the catalytic reaction component.

[0024] Furthermore, the reaction catalytic reaction component is located in the lower part of the distillation column, close to the bottom of the distillation column;

[0025] Preferably,

[0026] The random packing is located at the top of the catalytic reaction unit in the direction from the inlet to the outlet.

[0027] Furthermore, the catalytic reaction component is provided with a support structure for placing the catalyst;

[0028] Preferably,

[0029] The material of the support structure is the same as the material of the wrapping layer.

[0030] Furthermore, the random packing is selected from one or more of the following: θ ring packing, glass spring packing, calendered ring packing, and triangular spiral packing.

[0031] Furthermore, the device also includes a reboiler and a condenser.

[0032] Compared with the prior art, the beneficial effects of this application are as follows:

[0033] (1) The method provided in this application couples the reaction and distillation processes, saving equipment investment and enabling efficient utilization of heat.

[0034] (2) The catalytic reaction component of this application avoids direct contact between the catalyst and high-boiling-point benzyl alcohol, preventing high temperature from causing damage to the catalyst structure or other chemical reactions.

[0035] (3) The catalyst in this application has high reaction efficiency, and the purity and yield of the target product 1,1,2,2,3,3,4-heptafluorocyclopentane are high. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a reactive distillation column used for distillation. Detailed Implementation

[0037] In this application, "azeotropic composition" or "azeotrope" means a mixture in equilibrium with the liquid phase that exhibits the same composition as the liquid phase. An azeotrope refers to a mixture of two or more homogeneous solutions of different components, mixed in a specific ratio, that, under a fixed pressure, has only one boiling point. When an azeotrope reaches its azeotropic point, because the proportion of the gaseous component produced by boiling is exactly the same as that of the liquid component, the solution components cannot be separated by distillation or fractional distillation. In other words, the two components of an azeotrope cannot be separated by simple distillation or fractional distillation. In this application, tert-amyl alcohol and 1,1,2,2,3,3,4-heptafluorocyclopentane can form an azeotropic composition with a boiling point of 85°C.

[0038] In this application, the term "non-azeotropic composition" or "non-azeotropic substance" does not refer to an azeotropic point. During evaporation or condensation at a certain temperature, the compositions of the gas and liquid phases differ, and the temperature continuously changes from a saturated liquid to a two-phase region until complete evaporation. In this application, 1,1,2,2,3,3,4-heptafluorocyclopentane, benzyl alcohol, and tert-amyl alcohol constitute a non-azeotropic composition.

[0039] In the non-azeotropic composition, the mass ratio of 1,1,2,2,3,3,4-heptafluorocyclopentane, benzyl alcohol, and tert-amyl alcohol is 62:35:3.

[0040] The catalyst-catalyzed dehydration reactions involved in this application are as follows:

[0041]

[0042] Tertiary amyl alcohol undergoes a dehydration reaction with a catalyst to yield a mixture of 2-methyl-1-butene and 2-methyl-2-butene.

[0043] In this application, the mixture of 2-methyl-1-butene and 2-methyl-2-butene has a boiling point of 37°C, 1,1,2,2,3,3,4-heptafluorocyclopentane has a boiling point of 82°C, and benzyl alcohol has a boiling point of 206°C.

[0044] This application provides a method for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from a non-azeotropic composition, wherein the azeotropic composition is a non-azeotropic composition of tert-amyl alcohol, benzyl alcohol, and 1,1,2,2,3,3,4-heptafluorocyclopentane, wherein the non-azeotropic composition undergoes a dehydration reaction of tert-amyl alcohol under the action of a catalyst, and the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is obtained by distillation; the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is then subjected to an acid removal agent and a dehydration agent to remove acidic substances and water, respectively, to obtain the 1,1,2,2,3,3,4-heptafluorocyclopentane recovered product; the catalyst includes a main catalyst and a coating layer, the coating layer having a porous structure and coating the main catalyst; the catalyst does not contact the benzyl alcohol.

[0045] In this application, if the main catalyst comes into contact with benzyl alcohol, it will swell and crack. Therefore, to avoid this, this application uses a porous coating layer, mainly to fix the main catalyst and prevent it from directly contacting benzyl alcohol.

[0046] In some embodiments of this application, the coating layer is made of polyurethane, nylon filament, or polytetrafluoroethylene. The applicant has discovered that only when the coating layer is made of polyurethane, nylon filament, or polytetrafluoroethylene will the coating layer not undergo a chemical reaction with benzyl alcohol or other changes affecting its properties. Otherwise, the coating layer is prone to partial incompatibility with benzyl alcohol, leading to problems such as coating layer dissolution.

[0047] In some embodiments of this application, the minimum pore size of the porous structure of the coating layer is greater than the maximum pore size of the main catalyst. Here, "pore size of the porous structure" refers to the size of the pores in the porous structure, and the specific pore size of the porous structure of the coating layer can be purchased according to actual needs.

[0048] "Main catalyst pore size" refers to the diameter of the main catalyst particles. In some specific embodiments, the main catalyst pore size can be selected according to actual needs, such as 1 mm, 3 mm, 5 mm or 8 mm.

[0049] In some embodiments of this application, the catalyst is 0.01-0.5 parts by weight, relative to 1 part by weight of the azeotropic composition;

[0050] For example, compared to 1 part by weight of the azeotropic composition, the catalyst can be 0.01 parts by weight, 0.02 parts by weight, 0.03 parts by weight, 0.04 parts by weight, 0.05 parts by weight, 0.06 parts by weight, 0.07 parts by weight, 0.08 parts by weight, 0.09 parts by weight, 0.1 parts by weight, 0.11 parts by weight, 0.12 parts by weight, 0.13 parts by weight, 0.14 parts by weight, 0.15 parts by weight, 0.16 parts by weight, 0.17 parts by weight, 0.18 parts by weight, 0.19 parts by weight, 0.2 parts by weight, 0.21 parts by weight, 0.22 parts by weight, 0.23 parts by weight, or 0.24 parts by weight. 0.25 parts by weight, 0.26 parts by weight, 0.27 parts by weight, 0.28 parts by weight, 0.29 parts by weight, 0.3 parts by weight, 0.31 parts by weight, 0.32 parts by weight, 0.33 parts by weight, 0.34 parts by weight, 0.35 parts by weight, 0.36 parts by weight, 0.37 parts by weight, 0.38 parts by weight, 0.39 parts by weight, 0.4 parts by weight, 0.41 parts by weight, 0.42 parts by weight, 0.43 parts by weight, 0.44 parts by weight, 0.45 parts by weight, 0.46 parts by weight, 0.47 parts by weight, 0.48 parts by weight, 0.49 parts by weight, 0.5 parts by weight, or any range between these.

[0051] In some embodiments of this application, the main catalyst is selected from one or more of type A molecular sieves, type Y molecular sieves, type X molecular sieves, HZSM-5 molecular sieves, and strongly acidic cation exchange resins.

[0052] In some embodiments of this application, the strong acid cation exchange resin is selected from one or more of NKC-9, 001*7, D001, and D75.

[0053] In some embodiments of this application, the mass ratio of 1,1,2,2,3,3,4-heptafluorocyclopentane, benzyl alcohol, and tert-amyl alcohol in the non-azeotropic composition is 35:62:3. In some embodiments of this application, the mass ratio of the acid remover to the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is 1:(2-10).

[0054] In some embodiments of this application, the acid remover is selected from one or more of type A, type Y, type X molecular sieves, and activated alumina.

[0055] In some embodiments of this application, the acid removal reaction time is 1-120 hours, preferably 24-120 hours.

[0056] In some embodiments of this application, the mass ratio of the dehydrating agent to the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is 1:(2-10).

[0057] In some embodiments of this application, the dehydrating agent is selected from one or more of the following: color-changing silica gel, anhydrous calcium chloride, anhydrous magnesium sulfate, anhydrous sodium carbonate, anhydrous sodium sulfate, molecular sieve, and activated alumina.

[0058] In some embodiments of this application, the water removal reaction time is 1-120 hours, preferably 24-120 hours.

[0059] This application provides an apparatus for implementing the above method, such as... Figure 1 As shown, the reactive distillation column used for distillation includes a column body, and the column body is provided with a catalytic reaction component and a random packing material in sequence from the feed inlet to the discharge outlet. The catalytic reaction component contains the catalyst.

[0060] In a specific embodiment, the catalytic reaction component is located inside the distillation column and does not directly contact the bottom material. For example, the catalytic reaction component is located in the lower part of the distillation column.

[0061] like Figure 1 As shown, the random packing is located at the top of the catalytic reaction unit in the direction from the inlet to the outlet.

[0062] like Figure 1 As shown, the catalytic reaction component has a support structure for placing the catalyst.

[0063] In a specific implementation, the material of the support structure is the same as the material of the wrapping layer.

[0064] In a specific embodiment, the random packing is selected from one or more of the following: θ-ring packing, glass spring packing, calendered ring packing, and triangular spiral packing.

[0065] In this application, the maximum operating temperature of the main catalyst is 120°C.

[0066] like Figure 1 As shown, the device also includes a reboiler and a condenser.

[0067] In this application, a reactive distillation column is used to couple the dehydration reaction of tert-amyl alcohol and the distillation process of 1,1,2,2,3,3,4-heptafluorocyclopentane. In this application, using this reactive distillation column, the cleaning agent to be treated is introduced into the column reboiler and heated to boiling using a reboiler. The heating power of the reboiler is controlled to maintain the temperature of the internal components of the catalytic reaction column at 60-100℃, the overall operating pressure of the column at 0-0.2 MPa (gauge pressure), and the condenser temperature at 5-20℃. After maintaining total reflux until the temperature and pressure at the top of the column are constant, the reflux ratio is adjusted to (1-5):1. The product with an outlet temperature of 30-75℃ is collected as the fore fraction; the fraction with an outlet temperature of 75-85℃ is collected as the 1,1,2,2,3,3,4-heptafluorocyclopentane recovery product.

[0068] In a specific embodiment, benzyl alcohol has a boiling point of 206°C, and the temperature of the internal components of the catalytic reaction tower is maintained at 60-100°C. Therefore, benzyl alcohol remains in the bottom of the reactive distillation tower throughout the entire reactive distillation stage. As the catalytic dehydration reaction proceeds, the mixture of 2-methyl-1-butene and 2-methyl-2-butene, the products of tert-amyl alcohol dehydration, has a boiling point of 37°C, and 1,1,2,2,3,3,4-heptafluorocyclopentane has a boiling point of 82°C. In the pre-fraction collected at 30-75°C, 2-methyl-1-butene and 2-methyl-2-butene are the main components, while 1,1,2,2,3,3,4-heptafluorocyclopentane accounts for a small proportion. At this point, the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction does not meet the requirements. At 75-85℃, the collected fraction is mainly 1,1,2,2,3,3,4-heptafluorocyclopentane with a purity of about 98-99.9%, which meets the purity requirements.

[0069] This application provides a general and / or specific description of the materials and test methods used in the experiments. In the following examples, unless otherwise specified, % represents wt%, i.e., weight percentage. Reagents or instruments used, unless otherwise specified, are all commercially available conventional reagent products.

[0070] Example

[0071] Example 1

[0072] like Figure 1 The reactive distillation column shown includes a column body, within which, from the feed inlet to the discharge outlet, are sequentially arranged a catalytic reaction unit and random packing. The catalytic reaction unit contains the catalyst and a supporting structure. The catalytic reaction unit is located at the bottom of the distillation column and does not directly contact the bottom material.

[0073] 1 kg of used cleaning agent was added to the bottom of a 2 L reactive distillation column. The cleaning agent had the following composition: 1,1,2,2,3,3,4-heptafluorocyclopentane: benzyl alcohol: tert-amyl alcohol in a mass ratio of 62:35:3. 100 g of NKC-9 strong acid cation exchange resin with a diameter of 1.5 mm was wrapped with 20-mesh nylon wire mesh. The main catalyst was NKC-9 strong acid cation exchange resin. The wrapping layer was a porous nylon wire mesh with a pore size of 0.5 mm. The catalyst dosage was 100 g. The support structure was made of nylon wire. The catalyst and support structure were loaded together into the catalytic reaction component of the column with a diameter of 50 mm. Random packing material was used to fill the column body above the catalytic reaction component. The packing height was 1 m. The random packing material was 3 mm θ-ring stainless steel wire mesh.

[0074] The condensation temperature of the catalytic reaction distillation column is 15℃, the operating pressure is 0MPa (gauge pressure), the temperature of the catalytic reaction section is 82℃, and the reflux ratio is 4:1.

[0075] A total of 125g of the fraction collected at 30-75℃ and a total of 498g of the fraction collected at 75-82℃ were obtained.

[0076] Example 2

[0077] The only difference between Example 2 and Example 1 is that the main catalyst is HZSM-5 strong acid cation exchange resin, while the other conditions are the same.

[0078] Example 3

[0079] The only difference between Example 3 and Example 1 is that the main catalyst is 13X molecular sieve strong acid cation exchange resin, while the other conditions are the same.

[0080] Example 4

[0081] The only difference between Example 4 and Example 1 is that the main catalyst is Y molecular sieve strong acid cation exchange resin, while the other conditions are the same.

[0082] Example 5

[0083] The only difference between Example 5 and Example 1 is that the main catalyst is 5A molecular sieve strong acid cation exchange resin, while the other conditions are the same.

[0084] Example 6

[0085] The only difference between Example 6 and Example 1 is that the wrapping layer is a polytetrafluoroethylene mesh with a porous structure; all other conditions are the same.

[0086] Example 7

[0087] The only difference between Example 7 and Example 1 is that the wrapping layer is a polyurethane mesh with a porous structure; all other conditions are the same.

[0088] Example 8

[0089] The only difference between Example 8 and Example 1 is that the wrapping layer is a PET polyester plastic mesh with a porous structure; all other conditions are the same.

[0090] Example 9

[0091] The only difference between Example 9 and Example 1 is that the random packing is 3mm calendered ring packing, and the other conditions are the same.

[0092] Example 10

[0093] The only difference between Example 10 and Example 1 is that the catalyst and the supporting structure are placed together in the bottom of the reactive distillation column, and the catalyst is filled into the column body with random packing material with a height of 1m. The random packing material is 3mm θ-ring stainless steel wire mesh.

[0094] Comparative Example 1

[0095] The only difference between Comparative Example 1 and Example 1 is that zinc chloride is placed in the bottom of the reactive distillation column, and random packing is used to fill the column body above the catalyst. The packing height is 1m, and the random packing is 3mm θ-ring stainless steel wire mesh.

[0096] Comparative Example 2

[0097] The only difference between Comparative Example 2 and Example 1 is that concentrated sulfuric acid was placed in the bottom of the reactive distillation column, and random packing was used to fill the column body above the catalyst. The packing height was 1m, and the random packing was 3mm θ-ring stainless steel wire mesh.

[0098] Comparative Example 3

[0099] The only difference between Comparative Example 3 and Example 1 is that NKC-9 strong acid cation exchange resin was placed in the bottom of the reactive distillation column, and random packing was used to fill the column body above the catalyst. The packing height was 1m, and the random packing was 3mm θ-ring stainless steel wire mesh.

[0100] Table 1

[0101]

[0102] Of Examples 1-5, the strongly acidic cation exchange resin exhibited the best catalytic effect, followed by HZSM-5 molecular sieve, which required the shortest time. In Examples 6-7, replacing the coating layer with polytetrafluoroethylene (PTFE) mesh and polyurethane mesh had little impact on the catalyst's catalytic efficiency. In Example 8, the PET polyester mesh coating layer dissolved in benzyl alcohol due to incompatibility. In Example 10, the catalyst was placed in the bottom of a distillation column, allowing the main catalyst to contact and dissolve in benzyl alcohol. Comparative Example 1 used a solid acid catalyst, zinc chloride, but zinc chloride dissolved in benzyl alcohol and underwent other chemical reactions, thus losing its catalytic activity. Consequently, the tert-amyl alcohol in the cleaning agent could not undergo a dehydration reaction, failing to disrupt the binary azeotropic system, and therefore, high-purity 1,1,2,2,3,3,4-heptafluorocyclopentane was not obtained. Concentrated sulfuric acid, a liquid acid catalyst, reacts chemically with benzyl alcohol and also catalyzes the dehydration of some tert-amyl alcohol. The resulting water dilutes the concentrated sulfuric acid, significantly reducing its catalytic activity; therefore, high-purity 1,1,2,2,3,3,4-heptafluorocyclopentane was not collected in Comparative Example 2. In Comparative Example 3, the NKC-9 catalyst was placed in the bottom of the distillation column, directly contacting benzyl alcohol. This contact caused the NKC-9 catalyst to swell and rupture, resulting in loss of catalytic activity.

[0103] Experimental Example

[0104] Yield refers to the overall yield, specifically the ratio of the mass of collected 1,1,2,2,3,3,4-heptafluorocyclopentane multiplied by 99% to the mass of 1,1,2,2,3,3,4-heptafluorocyclopentane in the feedstock. The calculation method is as follows:

[0105]

[0106] In the formula:

[0107] m F7A : 1,1,2,2,3,3,4-heptafluorocyclopentane, multiplied by 99%, g

[0108] M 原料 : The quality of the raw materials input, in grams

[0109] Mass fraction (%) of 1,1,2,2,3,3,4-heptafluorocyclopentane in the raw material

[0110] The distillation yield is the ratio of the mass of the collected 1,1,2,2,3,3,4-heptafluorocyclopentane multiplied by 99% to the mass of the feedstock. The calculation method is as follows:

[0111]

[0112] In the formula:

[0113] mF7A : 1,1,2,2,3,3,4-heptafluorocyclopentane, multiplied by 99%, g

[0114] M 原料 : 62% of the mass of the raw materials input, g

[0115] Table 2

[0116]

[0117]

[0118] As shown in Table 2, Comparative Example 1 used a solid acid catalyst, zinc chloride. However, zinc chloride dissolved in benzyl alcohol and underwent other chemical reactions, thus losing its catalytic activity. This prevented the dehydration of tert-amyl alcohol in the cleaning agent and the disruption of the binary azeotropic system, resulting in the failure to obtain high-purity 1,1,2,2,3,3,4-heptafluorocyclopentane. The liquid acid catalyst, concentrated sulfuric acid, reacted with benzyl alcohol and also catalyzed the dehydration of some tert-amyl alcohol. The resulting water diluted the concentrated sulfuric acid, significantly reducing its catalytic activity. Therefore, Comparative Example 2 did not yield high-purity 1,1,2,2,3,3,4-heptafluorocyclopentane. In Comparative Example 3, the NKC-9 catalyst was placed in the bottom of the distillation column, directly contacting benzyl alcohol. This contact caused the NKC-9 catalyst to swell and rupture, losing its catalytic effect. Examples 1-10 used the apparatus of this application. The NKC-9 catalyst did not directly contact benzyl alcohol, avoiding a chemical reaction. Simultaneously, the catalyst's operating temperature was maintained at 78°C, not exceeding its maximum operating temperature (120°C), thus ensuring stable catalyst structure and performance. Table 2 shows that Examples 1-5 all achieved the separation and recovery of 1,1,2,2,3,3,4-heptafluorocyclopentane from the cleaning agent, with a product purity of approximately 99%. The experimental results using NKC-9 strong acid cation exchange resin as the catalyst were the best, achieving a product purity of 99.2% and a 1,1,2,2,3,3,4-heptafluorocyclopentane yield of 80.3%. In Examples 8 and 10, the PET polyester plastic mesh layer dissolved in benzyl alcohol due to its incompatibility with the formaldehyde.

[0119] Experimental Example 1

[0120] In Experiment 1, the method of Comparative Example 3 was used, with 10 consecutive feedings. After each feeding, the morphology of the catalyst and the product yield were tested. The catalyst was then recovered and fed again, and the morphology of the catalyst and the product yield were tested again.

[0121] Experiment Example 2

[0122] Experimental Example 2 followed the method of Example 1, with 10 consecutive feedings. After each feeding, the morphology of the catalyst and the product yield were tested. The catalyst was then recovered before the next feeding, and the morphology of the catalyst and the product yield were tested again. The parameters are shown in Table 3.

[0123] The results of Experiment 1 and Experiment 2 are shown in Table 4.

[0124] Table 3

[0125]

[0126] Table 4

[0127]

[0128] As shown in Table 4, in Experiment 2, the catalyst was directly added to the bottom of the column. Although the purity of the collected 1,1,2,2,3,3,4-heptafluorocyclopentane remained around 99% with increasing number of feed cycles, the actual yield decreased significantly, by 24%. The catalyst showed significant damage and structural disruption after 10 cycles. In Experiment 2, the catalytic reaction-distillation coupling device provided in this application was used. The catalyst did not directly contact the high-boiling-point bottom material, and the actual operating temperature was lower than its maximum tolerance temperature. Therefore, after 10 cycles, the catalyst's structure and performance remained stable. The purity of the collected product was around 99%, and the yield was around 80%.

[0129] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Anyone skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent application.

Claims

1. A method for recovering 1,1,2,2,3,3,4-heptafluorocyclopentane from a non-azeotropic composition, wherein the non-azeotropic composition is a non-azeotropic composition of tert-amyl alcohol, benzyl alcohol, and 1,1,2,2,3,3,4-heptafluorocyclopentane, wherein, The non-azeotropic composition undergoes a dehydration reaction of tert-amyl alcohol under the action of a catalyst, and the 1,1,2,2,3,3,4-heptafluorocyclopentane fraction is obtained by distillation. The 1,1,2,2,3,3,4-heptafluorocyclopentane fraction was dehydrated by a dehydrating agent to obtain a 1,1,2,2,3,3,4-heptafluorocyclopentane recovery product. The catalyst includes a main catalyst and a coating layer, wherein the coating layer has a porous structure and encapsulates the main catalyst; The catalyst does not come into contact with the benzyl alcohol; The main catalyst is selected from one or more of type A molecular sieve, type Y molecular sieve, type X molecular sieve, HZSM-5 molecular sieve, and strong acid cation exchange resin; the strong acid cation exchange resin is selected from one or more of NKC-9, 001*7, D001, and D75. The material of the wrapping layer is polyurethane, nylon filament, or polytetrafluoroethylene; The minimum pore size of the porous structure of the coating layer is greater than the maximum pore size of the main catalyst; The catalyst is 0.01-0.5 parts by weight, compared to 1 part by weight of the azeotropic composition.

2. The method according to claim 1, characterized in that, In the non-azeotropic composition, the mass ratio of 1,1,2,2,3,3,4-heptafluorocyclopentane, benzyl alcohol, and tert-amyl alcohol is 62:35:

3.

3. The method according to claim 1, characterized in that, The acidic substances in the 1,1,2,2,3,3,4-heptafluorocyclopentane recoverable were removed by an acid-removing agent to obtain the acid-removed 1,1,2,2,3,3,4-heptafluorocyclopentane recoverable.

4. An apparatus for implementing the method according to any one of claims 1 to 3, characterized in that, The reactive distillation column used for distillation includes a column body, and the column body is provided with a catalytic reaction unit and random packing from the feed inlet to the discharge outlet. The catalyst is provided within the catalytic reaction component.

5. The apparatus according to claim 4, characterized in that, The catalytic reaction component is located in the lower part of the distillation column, close to the bottom of the distillation column.

6. The apparatus according to claim 5, characterized in that, The random packing is located at the top of the catalytic reaction unit in the direction from the inlet to the outlet.

7. The apparatus according to claim 4, characterized in that, The catalytic reaction component is provided with a support structure for placing the catalyst.

8. The apparatus according to claim 7, characterized in that, The material of the support structure is the same as the material of the wrapping layer.

9. The apparatus according to claim 4, characterized in that, Random packing is selected from one or more of the following: θ-ring packing, glass spring packing, calendered ring packing, and triangular spiral packing.

10. The apparatus according to claim 4, characterized in that, The device also includes a reboiler and a condenser.

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