Method and device for separating and purifying 1-chloro-1, 1-difluoroethane

Abstract

The invention provides a 1-chloro-1, 1-difluoroethane separation and purification method and device, and the method comprises the following steps: 1) carrying out deacidification-dehydration treatment on a to-be-separated mixture to obtain a first intermediate; the mixture to be separated is prepared from 1-chloro-1, 1-difluoroethane, 2-chloro-1, 1-difluoroethane, 1, 1-difluoroethane and hydrogen chloride; 2) performing pressurization treatment and heat exchange liquefaction treatment on the first intermediate to obtain a liquid-phase intermediate; and 3) sequentially carrying out light component removal treatment and heavy component removal treatment on the liquid-phase intermediate to obtain the 1-chloro-1, 1-difluoroethane, wherein a heat exchange medium of the heat exchange liquefaction treatment is derived from a reflux heavy component of the heavy component removal treatment, and the separation and purification method provided by the invention can realize high-efficiency separation of a product and improve the utilization efficiency of resources and energy.

Description

Technical Field

[0001] The invention relates to a method for separating and purifying 1-chloro-1,1-difluoroethane, in particular to a method and device for separating and purifying 1-chloro-1,1-difluoroethane, belonging to the technical field of fluorine chemical industry. Background Art

[0002] 1-Chloro-1,1-difluoroethane (R142b) is a widely used fluorine-containing compound that can be used as a refrigerant, foaming agent, propellant, etc. Due to its low damage to the ozone layer, it is one of the substitutes for traditional Freon. In addition, 1-chloro-1,1-difluoroethane is an important raw material for the synthesis of 1,1-difluoroethylene, which is a monomer for the production of polyvinylidene fluoride resin PVDF. PVDF, as a functional polymer material with good comprehensive properties, can be used in many aspects such as electronics, aerospace, etc., especially as a lithium battery adhesive. Therefore, the industrial production of 1-chloro-1,1-difluoroethane is of great significance.

[0003] In industry, 1-chloro-1,1-difluoroethane is usually prepared from difluoroethane and chlorine gas as raw materials through photochlorination reaction. However, the prepared product may contain impurities such as by-product 2-chloro-1,1-difluoroethane and residual raw materials. How to achieve efficient separation of products and improve resource and energy utilization efficiency has become a technical problem that needs to be urgently solved by technicians in this field. Summary of the invention

[0004] The invention provides a method for separating and purifying 1-chloro-1,1-difluoroethane. The method can realize efficient separation of 1-chloro-1,1-difluoroethane and improve the utilization efficiency of resources and energy.

[0005] The present invention also provides a device for separating and purifying 1-chloro-1,1-difluoroethane, which is used to perform the above separation and purification method and can achieve efficient separation of 1-chloro-1,1-difluoroethane.

[0006] In one aspect, the present invention provides a method for separating and purifying 1-chloro-1,1-difluoroethane, comprising the following steps:

[0007] 1) performing a deacidification-dehydration treatment on a mixture to be separated to obtain a first intermediate; the mixture to be separated comprises 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane, 1,1-difluoroethane, and hydrogen chloride;

[0008] 2) subjecting the first intermediate to a pressurization treatment and a heat exchange liquefaction treatment to obtain a liquid intermediate;

[0009] 3) The liquid intermediate is subjected to light removal treatment and heavy removal treatment in sequence to obtain the 1-chloro-1,1-difluoroethane; wherein the heat exchange medium of the heat exchange liquefaction treatment is derived from the reflux heavy component of the heavy removal treatment.

[0010] In the separation and purification method as described above, the mixture to be separated is derived from the reaction liquid of the photochlorination reaction.

[0011] In the separation and purification method as described above, in the light removal treatment, the light components removed include 1,1-difluoroethane.

[0012] In the separation and purification method as described above, in the de-heavy treatment, the removed heavy components also include the heavy components to be separated;

[0013] The heavy components to be separated are separated and recovered to obtain 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane and heavy component waste liquid respectively.

[0014] In the separation and purification method as described above, the deacidification-dehydration treatment includes deacidification treatment and dehydration treatment in sequence; wherein,

[0015] The deacidification treatment comprises contacting the mixture to be separated with water in reverse at 30° C. to 80° C. and a pressure of 0.01 MPa to 0.8 MPa to obtain a deacidification intermediate;

[0016] The dehydration treatment includes contacting the deacidified intermediate with a solid alkaline substance at 10° C. to 80° C. and a pressure of 0.01 MPa to 1.0 MPa to obtain the first intermediate.

[0017] In the separation and purification method as described above, the pressure of the pressurized treatment is 1.5MPa to 4MPa, and the temperature is 120°C to 220°C;

[0018] And / or, the heat exchange liquefaction treatment has a pressure of 1.5 MPa to 4.0 MPa and a temperature of 60° C. to 200° C.;

[0019] And / or, the tower top pressure of the light removal treatment is 0.5MPa-2.0MPa, the tower top temperature is 30°C-100°C, and the tower bottom temperature is 50°C-150°C;

[0020] And / or, the tower top pressure of the deweighting treatment is 0.5MPa-1.0MPa, the tower top temperature is 30°C-100°C, and the tower bottom temperature is 50°C-150°C;

[0021] And / or, the tower top pressure of the separation and recovery is 0.1MPa-1.0MPa, the tower top temperature is 0°C-70°C, and the tower bottom temperature is 40°C-100°C.

[0022] In another aspect, the present invention provides a device for separating and purifying 1-chloro-1,1-difluoroethane, wherein the device is used to perform the separation and purification method as described above;

[0023] It includes a deacidification-dehydration treatment unit, a pressurization treatment unit, a heat exchange liquefaction treatment unit, a light removal treatment unit, and a heavy removal treatment unit;

[0024] The deacidification-dehydration treatment unit comprises an inlet for receiving a mixture to be separated, a first intermediate outlet of the deacidification-dehydration treatment unit is communicated with the inlet of the pressurization treatment unit, the outlet of the pressurization treatment unit is communicated with the heat medium inlet of the heat exchange liquefaction treatment unit, the heat medium outlet of the heat exchange liquefaction treatment unit is communicated with the inlet of the light removal treatment unit, the liquid phase outlet of the light removal treatment unit is communicated with the liquid phase inlet of the heavy removal treatment unit, and the gas phase outlet of the heavy removal treatment unit is used to output the 1-chloro-1,1-difluoroethane;

[0025] The reflux heavy component outlet of the de-weighting unit is communicated with the cold medium inlet of the heat exchange liquefaction unit, and the cold medium outlet of the heat exchange liquefaction unit is communicated with the reflux heavy component inlet of the de-weighting unit.

[0026] The device as described above further comprises a photochlorination reaction unit,

[0027] The light component outlet of the light component removal treatment unit is communicated with the raw material inlet of the photochlorination reaction unit.

[0028] The device as described above further comprises a separation and recovery unit;

[0029] The separation and recovery unit includes a top reflux light component outlet and a side line 2-chloro-1,1-difluoroethane byproduct production outlet;

[0030] The outlet of the heavy component to be separated of the de-weighting processing unit is communicated with the inlet of the heavy component to be separated of the separation and recovery unit.

[0031] The device as described above, wherein the deacidification-dehydration treatment unit comprises a deacidification treatment unit and a dehydration treatment unit;

[0032] The deacidification intermediate outlet of the deacidification treatment unit is connected to the inlet of the dehydration treatment unit;

[0033] The inlet of the mixture to be separated is arranged in the deacidification treatment unit, and the outlet of the first intermediate is arranged in the dehydration treatment unit.

[0034] The separation and purification method provided by the present invention efficiently obtains 1-chloro-1,1-difluoroethane by sequentially subjecting the mixture to be separated to deacidification-dehydration treatment, pressurization treatment, heat exchange liquefaction treatment, light removal treatment, heavy removal treatment and other treatment processes, and improves the efficiency of resource and energy use through a multi-stage treatment method. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a separation and purification device provided in Example 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of the separation and purification device provided in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0038] In one aspect, the present invention provides a method for separating and purifying 1-chloro-1,1-difluoroethane, comprising the following steps:

[0039] 1) performing a deacidification-dehydration treatment on the mixture to be separated to obtain a first intermediate; the mixture to be separated includes 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane, 1,1-difluoroethane, and hydrogen chloride;

[0040] 2) subjecting the first intermediate to a pressurization treatment and a heat exchange liquefaction treatment to obtain a liquid intermediate;

[0041] 3) The liquid intermediate is subjected to light removal treatment and heavy removal treatment in sequence to obtain 1-chloro-1,1-difluoroethane; wherein the heat exchange medium for the heat exchange liquefaction treatment is derived from the reflux heavy component of the heavy removal treatment.

[0042] In the process of industrial preparation of 1-chloro-1,1-difluoroethane, the obtained mixture to be separated mainly includes 1-chloro-1,1-difluoroethane (R142b), 1,1-difluoroethane (R152), 2-chloro-1,1-difluoroethane (R142), 1,2-dichloro-1,1-difluoroethane (R132b), 2,2-dichloro-1,1-difluoroethane (R132a), 1,2,2-trichloro-1,1-difluoroethane (R122), 1,2,2,2-tetrachloro-1,1-difluoroethane (R112a), chlorine, hydrogen chloride, hydrogen fluoride, water, etc. The separation and purification method of the present invention is mainly used for separation and purification of the mixture to be separated to obtain the main product 1-chloro-1,1-difluoroethane with higher purity, so as to realize efficient utilization of resources and energy.

[0043] In detail, a mixture to be separated including 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane, 1,1-difluoroethane and hydrogen chloride is subjected to a deacidification-dehydration treatment to remove chlorine, hydrogen chloride, hydrogen fluoride, water and the like in the mixture to be separated, thereby obtaining a first intermediate including 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane, 1,1-difluoroethane and other high-boiling-point components.

[0044] It can be understood that the mixture to be separated may also include 1,2-dichloro-1,1-difluoroethane (R132b), 2,2-dichloro-1,1-difluoroethane (R132a), 1,2,2-trichloro-1,1-difluoroethane (R122), 1,2,2,2-tetrachloro-1,1-difluoroethane (R112a) and some other isomers or structurally similar heavy component impurities. After the deacidification-dehydration treatment, the heavy component impurities are retained in the first intermediate for subsequent treatment.

[0045] Subsequently, in step 2), the gaseous first intermediate is pressurized to obtain a pressurized first intermediate, and then the pressurized first intermediate is subjected to a heat exchange liquefaction treatment with a reflux heavy component obtained by a subsequent deweighting treatment, the cold of the reflux heavy component is transferred to the pressurized first intermediate, and the heat of the pressurized first intermediate is transferred to the reflux heavy component, and the gaseous first intermediate is converted into a liquid first intermediate through heat exchange liquefaction treatment.

[0046] By subjecting the refluxed heavy component to a heat exchange liquefaction treatment with the pressurized first intermediate, the energy consumption of the heat exchange liquefaction treatment and the subsequent de-weighting treatment can be saved, thereby improving the efficiency of energy and resource utilization.

[0047] In step 3), the liquid intermediate is subjected to a light removal treatment to remove light components in the liquid intermediate to obtain a target mixed solution including 1-chloro-1,1-difluoroethane. The target mixed solution also includes other heavy component impurities such as 2-chloro-1,1-difluoroethane. The target mixed solution is subjected to a heavy removal treatment to separate 1-chloro-1,1-difluoroethane and a reflux heavy component including heavy component impurities.

[0048] The separation and purification method provided by the present invention improves resource utilization efficiency by sequentially performing deacidification-dehydration treatment, pressurization treatment, heat exchange liquefaction treatment, light removal treatment and heavy removal treatment on the mixture to be separated. The reason is that: the present invention firstly adopts deacidification-dehydration treatment to absorb most of the acidic gas components in the mixture to be separated, including hydrogen chloride, hydrogen fluoride, chlorine and water, so as to avoid corrosion of the subsequent light removal treatment and heavy removal treatment equipment and pipelines by acidic liquid, thereby simplifying the process; in the light removal treatment and heavy removal treatment parts, the operating conditions are reasonably set to obtain the target light component 1,1-difluoroethane and the target heavy component 1-chloro-1,1-difluoroethane respectively, and the pressurized first intermediate and the recovered heavy component of the heavy removal treatment are subjected to heat exchange liquefaction treatment, thereby saving the energy consumption of the heat exchange liquefaction treatment and improving the energy utilization efficiency.

[0049] Furthermore, in a specific embodiment of the present invention, the mixture to be separated is derived from the reaction liquid of the photochlorination reaction.

[0050] In detail, 1,1-difluoroethane and chlorine are used as raw materials, and light energy is used to excite chlorine molecules to react with 1,1-difluoroethane to generate 1-chloro-1,1-difluoroethane. In this process, 1-chloro-1,1-difluoroethane, by-products generated by side reactions, and residual raw materials that have not reacted completely constitute the reaction liquid of the photochlorination reaction, and the mixed liquid to be separated comes from the reaction liquid of the photochlorination reaction.

[0051] The present invention does not limit the specific conditions of the photochlorination reaction. In a specific embodiment, the photochlorination reaction comprises the following steps:

[0052] At a temperature of 40°C to 90°C and a pressure of 0.01 to 0.5 MPa, 1,1-difluoroethane reacts with chlorine under ultraviolet light conditions to generate 1-chloro-1,1-difluoroethane, hydrogen chloride and by-products.

[0053] Furthermore, in a specific embodiment of the present invention, in the light removal treatment, the light components removed include 1,1-difluoroethane; and the process also includes recycling 1,1-difluoroethane as a raw material to participate in the photochlorination reaction.

[0054] In detail, by controlling the parameters of the light component removal treatment, the removed light components include 1,1-difluoroethane, which is recycled as a raw material to participate in the photochlorination reaction, thereby further improving the resource utilization efficiency.

[0055] Furthermore, in a specific embodiment of the present invention, in the de-heaving treatment, the removed heavy components also include the heavy components to be separated; the heavy components to be separated are separated and recovered to obtain 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane and heavy component waste liquid respectively.

[0056] The composition types of the heavy component to be separated and the reflux heavy component in the present invention are consistent. After the reflux heavy component and the pressurized first intermediate complete heat exchange liquefaction treatment, it can be separated and recovered as a part of the heavy component to be separated.

[0057] In detail, the heavy components removed by the de-heaving treatment include the heavy components to be separated, which include 2-chloro-1,1-difluoroethane, heavy component waste liquid and part of unseparated 1-chloro-1,1-difluoroethane. By adjusting the parameters for controlling separation and recovery, various substances in the heavy components to be separated are separated and recovered to obtain 2-chloro-1,1-difluoroethane, heavy component waste liquid and 1-chloro-1,1-difluoroethane.

[0058] Among them, 2-chloro-1,1-difluoroethane can be collected for industrial applications, such as refrigerants, foaming agents, solvents, etc., to improve the resource utilization efficiency of by-products.

[0059] In order to avoid pollution caused by the heavy component waste liquid, the heavy component waste liquid can be incinerated.

[0060] The 1-chloro-1,1-difluoroethane obtained by separation and recovery can further realize the recycling of the remaining 1-chloro-1,1-difluoroethane, thereby improving the resource recovery rate.

[0061] Further, in a specific embodiment of the present invention, the deacidification-dehydration treatment includes deacidification treatment and dehydration treatment in sequence; wherein, the deacidification treatment includes contacting the mixture to be separated with water in reverse at a temperature of 30°C to 80°C and a pressure of 0.01MPa to 0.8MPa to obtain a deacidification intermediate; the dehydration treatment includes contacting the deacidification intermediate with a solid alkaline substance at a temperature of 10°C to 80°C and a pressure of 0.01MPa to 1.0MPa to obtain a first intermediate.

[0062] Specifically, during the deacidification treatment process, at a temperature of 30°C to 80°C and a pressure of 0.01MPa to 0.8MPa, the mixture to be separated is fully contacted with water in reverse, and impurities such as hydrogen chloride, hydrogen fluoride, and chlorine in the mixture to be separated are absorbed by water, and most of the acidic components in the mixture to be separated are removed to obtain a deacidification intermediate.

[0063] In detail, the temperature of the deacidification treatment includes but is not limited to 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or a range between any two of them, and the pressure of the deacidification treatment includes but is not limited to 0.01MPa, 0.05MPa, 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa or a range between any two of them.

[0064] It is understandable that during the contact between the mixture to be separated and water, water may dissolve in the deacidification intermediate, so the deacidification intermediate includes 1-chloro-1,1-difluoroethane, difluoroethane and a small amount of residual hydrogen chloride, chlorine, water, etc.

[0065] The deacidified intermediate is subjected to a dehydration treatment at a temperature of 10°C to 80°C and a pressure of 0.01MPa to 1.0MPa, so that the deacidified intermediate is fully contacted with a solid alkaline substance, and residual hydrogen chloride, chlorine and water in the deacidified intermediate are removed to obtain a first intermediate.

[0066] The present invention does not limit the specific type of solid alkaline substance in the dehydration process, and common alkaline substances in the art can be selected, such as solid calcium hydroxide, sodium hydroxide or potassium hydroxide, and highly active solid calcium hydroxide is preferred because highly active calcium hydroxide has the advantages of higher specific surface area, higher pore volume and higher effective calcium content.

[0067] The mixture to be separated is subjected to deacidification-dehydration treatment in the above manner, which can effectively remove impurities such as hydrogen chloride, chlorine and a small amount of water in a step-by-step removal manner, thereby laying a foundation for subsequent separation and purification.

[0068] Further, in a specific embodiment of the present invention, the pressure of the pressurized treatment is 1.5MPa~4.0MPa, and the temperature is 120~220℃; and / or, the pressure of the heat exchange liquefaction treatment is 1.5MPa~4.0MPa, and the temperature is 60℃~200℃; and / or, the top pressure of the light removal treatment is 0.5MPa~2.0MPa, the top temperature is 30℃~100℃, and the bottom temperature is 50℃~150℃; and / or, the pressure of the heavy removal treatment is 0.5MPa~1.0MPa, the top temperature is 30℃~100℃, and the bottom temperature is 50℃~150℃; and / or, the top pressure of the separation and recovery is 0.1MPa~1.0MPa, the top temperature is 0℃~70℃, and the bottom temperature is 40℃~100℃.

[0069] By adjusting and controlling the processing parameters at each stage within the above range, efficient separation of various components in the mixture to be separated can be achieved.

[0070] like Figure 1As shown, the present invention provides a 1-chloro-1,1-difluoroethane separation and purification device on the one hand, which is used to perform the separation and purification method as described above; it includes a deacidification-dehydration treatment unit C, a pressurization treatment unit K1, a heat exchange liquefaction treatment unit H1, a light removal treatment unit C3, and a heavy removal treatment unit C4; the deacidification-dehydration treatment unit includes an inlet for receiving a mixture to be separated, the first intermediate outlet of the deacidification-dehydration treatment unit is connected to the inlet of the pressurization treatment unit K1, and the outlet of the pressurization treatment unit K1 is connected to the heat exchange liquid The hot medium inlet of the heat exchange liquefaction treatment unit H1 is connected, the hot medium outlet of the heat exchange liquefaction treatment unit H1 is connected with the inlet of the light removal treatment unit C3, the liquid phase outlet of the light removal treatment unit C3 is connected with the liquid phase inlet of the heavy removal treatment unit C4, and the gas phase outlet of the heavy removal treatment unit C4 is used to output 1-chloro-1,1-difluoroethane; the reflux heavy component outlet of the heavy removal treatment unit C4 is connected with the cold medium inlet of the heat exchange liquefaction treatment unit H1, and the cold medium outlet of the heat exchange liquefaction treatment unit H1 is connected with the reflux heavy component inlet of the heavy removal treatment unit H1.

[0071] In detail, the mixture to be separated enters the deacidification-dehydration treatment unit C through the mixture to be separated inlet of the deacidification-dehydration treatment unit C for deacidification-dehydration treatment to remove hydrogen chloride, chlorine and water to obtain a first intermediate. The first intermediate enters the pressurization treatment unit through the first intermediate outlet of the deacidification-dehydration treatment unit C and the inlet of the pressurization treatment unit K1 for pressurization treatment. The pressurized first intermediate enters the heat exchange liquefaction treatment unit H1 through the outlet of the pressurization treatment unit K1 and the heat medium inlet of the heat exchange liquefaction treatment unit H1. In the heat exchange liquefaction treatment unit H1, the pressurized first intermediate exchanges heat with the reflux heavy component in the subsequent deheavy treatment unit C4, and the gaseous first intermediate is converted into liquid. The liquid first intermediate enters the delight treatment unit C3 through the heat medium outlet of the heat exchange liquefaction treatment unit H1 and the inlet of the delight treatment unit C3 for delight treatment.

[0072] The liquid intermediate entering the light removal processing unit C3 is subjected to light removal treatment to separate the light component and the target mixed liquid including 1-chloro-1,1-difluoroethane. The target mixed liquid enters the heavy removal processing unit C4 through the bottom liquid phase outlet of the light removal processing unit C3 and the inlet of the heavy removal processing unit C4 for heavy removal treatment to separate 1-chloro-1,1-difluoroethane and a reflux heavy component. The reflux heavy component enters the heat exchange liquefaction processing unit through the reflux heavy component outlet and the cold medium inlet of the heat exchange liquefaction processing unit to perform heat exchange treatment with the pressurized first intermediate, and then returns to the heavy removal processing unit C4 through the cold medium outlet and the reflux heavy component inlet.

[0073] The present invention does not limit the device type of each unit, and common devices in the field can be selected. For example, the deacidification-dehydration treatment unit C uses a water washing tower and a solid alkali absorption tower, the pressurization treatment unit K1 uses a compressor, the heat exchange liquefaction unit H1 uses a heat exchanger, and the light removal treatment unit C3 and the heavy removal treatment unit C4 use plate distillation towers or packed distillation towers.

[0074] Furthermore, in a specific embodiment of the present invention, a photochlorination reaction unit (not shown) is also included, and the light component outlet of the light component removal treatment unit C3 is connected to the raw material inlet of the photochlorination reaction unit.

[0075] In detail, after the liquid intermediate is delightened in the delightening treatment unit C3, a light component including difluoroethane and a target mixed liquid are separated, and the light component is transported to the raw material inlet of the photochlorination reaction unit and enters the photochlorination reaction unit through the raw material inlet, thereby realizing effective recycling of resources.

[0076] Furthermore, in a specific embodiment of the present invention, it also includes a separation and recovery unit C5; the separation and recovery unit C5 includes a top reflux light component outlet, a side line 2-chloro-1,1-difluoroethane by-product production outlet, and the heavy component to be separated outlet of the de-heavy treatment unit is connected to the heavy component to be separated inlet of the separation and recovery unit.

[0077] In detail, the heavy component to be separated produced by the heavy component removal processing unit C4 enters the separation and recovery unit C5 through the heavy component outlet to be separated and the heavy component inlet to be separated of the separation and recovery unit C5 for separation and recovery, and obtains a reflux light component, 2-chloro-1,1-difluoroethane and a heavy component waste liquid, wherein the reflux light component includes residual 1-chloro-1,1-difluoroethane, and the reflux light component is combined with the 1-chloro-1,1-difluoroethane output from the heavy component removal unit C4 through the reflux light component outlet located at the top of the separation and recovery unit C5 and is output as the main product.

[0078] The 2-chloro-1,1-difluoroethane is output and collected through the 2-chloro-1,1-difluoroethane by-product outlet located on the side line of separation and recovery unit C5, and the heavy component waste liquid is discharged through the heavy component waste liquid outlet located below separation and recovery unit C5. In order to avoid the pollution of the heavy component waste liquid to the environment, the heavy component waste liquid can be transported to the incineration device for incineration treatment.

[0079] The present invention does not limit the specific device type of the separation and recovery unit C5, and a common device in the art, such as a distillation tower, may be selected.

[0080] Furthermore, in a specific embodiment of the present invention, the deacidification-dehydration treatment unit C includes a deacidification treatment unit C1 and a dehydration treatment unit C2; the deacidification intermediate outlet of the deacidification treatment unit C1 is connected to the inlet of the dehydration treatment unit C2; the inlet of the mixture to be separated is set in the deacidification treatment unit C1, and the first intermediate outlet is set in the dehydration treatment unit C2.

[0081] Specifically, the mixture to be separated enters the deacidification treatment unit C1 through the mixture to be separated inlet of the deacidification treatment unit C1 for deacidification treatment, removes most of the hydrogen chloride, and obtains a deacidification intermediate. The deacidification intermediate enters the dehydration treatment unit C2 through the deacidification intermediate outlet and the inlet of the dehydration treatment unit C2 for dehydration treatment, removes residual hydrogen chloride, chlorine and water, and obtains a first intermediate. The first intermediate enters the subsequent pressurization treatment unit K1 through the first intermediate outlet.

[0082] The separation and purification method and device provided by the present invention are described in detail below through specific examples.

[0083] Example 1

[0084] The device provided in this embodiment is as follows Figure 1 As shown, it includes a deacidification treatment unit C1, a dehydration treatment unit C2, a pressurization treatment unit K1, a heat exchange liquefaction treatment unit H1, a light removal treatment unit C3, a heavy removal treatment unit C4, and a separation and recovery unit C5; the deacidification treatment unit C1 includes an inlet for receiving a mixture to be separated, the deacidification intermediate outlet of the deacidification treatment unit C1 is connected to the inlet of the dehydration treatment unit C2, the first intermediate outlet of the dehydration treatment unit C2 is connected to the inlet of the pressurization treatment unit K1, the outlet of the pressurization treatment unit K1 is connected to the hot medium inlet of the heat exchange liquefaction treatment unit H1, and the heat exchange liquefaction treatment unit The hot medium outlet of H1 is connected to the inlet of the light removal processing unit C3, the liquid phase outlet of the light removal processing unit C3 is connected to the liquid phase inlet of the heavy removal processing unit C4, and the top outlet of the heavy removal processing unit C4 is used to output 1-chloro-1,1-difluoroethane (R142) product; the reflux heavy component outlet of the heavy removal processing unit C4 is connected to the cold medium inlet of the heat exchange liquefaction processing unit H1, the cold medium outlet of the heat exchange liquefaction processing unit H1 is connected to the reflux heavy component inlet of the heavy removal processing unit H1, and the heavy component to be separated outlet of the heavy removal processing unit C4 is connected to the heavy component to be separated inlet of the separation and recovery unit C5.

[0085] The light component removal unit C3 also includes a light component outlet, which is connected to the raw material inlet of the photochlorination reaction unit (not shown in the figure). The separation and recovery unit C5 includes a reflux light component outlet located at the top, a 2-chloro-1,1-difluoroethane outlet located at the side line, and a heavy component waste liquid outlet located at the bottom. The reflux light component outlet is mixed with the logistics at the top of the heavy component removal unit C4 as the final 1-chloro-1,1-difluoroethane product.

[0086] The method for separating and purifying 1-chloro-1,1-difluoroethane provided in this embodiment comprises the following steps:

[0087] 1. The mixture to be separated from the reaction liquid of the photochlorination reaction enters the deacidification treatment unit C1 for deacidification treatment. At a temperature of 40°C and a pressure of 0.2MPa, the mixture to be separated is reversely fully contacted with water, so that most of the acidic gases such as hydrogen chloride, hydrogen fluoride and chlorine in the mixture to be separated are dissolved in water and separated from the gas mixture, thereby obtaining a deacidified intermediate. The deacidified intermediate enters the dehydration treatment unit C2 through the deacidification intermediate outlet of the deacidification treatment unit C1 and the inlet of the dehydration treatment unit C2. At a temperature of 20°C and a pressure of 0.2MPa, the deacidified intermediate is fully contacted with a solid alkaline substance to further remove residual acidic gas and water, thereby obtaining a first intermediate.

[0088] The mixture to be separated includes 1-chloro-1,1-difluoroethane (R142b), 1,1-difluoroethane (R152), 2-chloro-1,1-difluoroethane (R142), 1,2-dichloro-1,1-difluoroethane (R132b), 2,2-dichloro-1,1-difluoroethane (R132a), 1,2,2-trichloro-1,1-difluoroethane (R122), 1,2,2,2-tetrachloro-1,1-difluoroethane (R112a), chlorine, hydrogen chloride, and hydrogen fluoride. The solid alkaline substance in the dehydration treatment unit C2 is calcium hydroxide in porous granular form.

[0089] 2. The first intermediate enters the pressure treatment unit K1 through the outlet of the dehydration treatment unit C2 and the inlet of the pressure treatment unit K1 for pressure treatment. The pressure treatment temperature is 158°C and the pressure is 2.1 MPa to obtain a pressurized first intermediate. Subsequently, the pressurized first intermediate enters the heat exchange liquefaction unit H1 through the outlet of the pressure treatment unit K1 and the heat medium inlet of the heat exchange liquefaction unit H1 for heat exchange liquefaction treatment. The pressure is 2.0 MPa and the temperature is 80°C to obtain a liquid first intermediate. The liquid first intermediate passes through the heat medium outlet of the heat exchange liquefaction unit H1.

[0090] 3. The liquid intermediate enters the light removal treatment unit C3 through the outlet of the heat exchange liquefaction unit H1 and the inlet of the light removal treatment unit C3, where the tower top temperature is 51°C and the pressure is 1.0 MPa for light removal treatment to obtain difluoroethane (R152a) and a target mixed liquid. The difluoroethane is transported to the raw material inlet of the photochlorination reaction unit through the gas phase outlet above and circulated to participate in the photochlorination reaction. The target mixed liquid enters the heavy removal treatment unit C4 through the liquid phase outlet at the bottom of the light removal treatment unit C3 and the inlet of the heavy removal treatment unit C4, where the tower top temperature is 38.4°C and the pressure is 0.4 MPa. The tower bottom temperature is 74°C, and the obtained 1-chloro-1,1-difluoroethane and reflux heavy component are output through the top outlet of the heavy-removal processing unit C4, and then merged with the 1-chloro-1,1-difluoroethane coming out of the top of the separation and recovery unit C5 and collected. The reflux heavy component enters the heat exchange liquefaction processing unit H1 through the reflux heavy component outlet and the cold medium inlet of the heat exchange liquefaction processing unit H1, and performs heat exchange treatment with the pressurized first intermediate, and then returns to the heavy-removal processing unit C4 through the cold medium outlet and the reflux heavy component inlet.

[0091] 4. The heavy components (including the reflux heavy components) obtained by the deheaving treatment in the deheaving treatment unit C4 enter the separation and recovery unit C5 through the outlet of the heavy components to be separated and the inlet of the heavy components to be separated of the separation and recovery unit C5, and are separated and recovered at a tower top temperature of 9°C and a pressure of 0.1MPa to obtain reflux light components, 2-chloro-1,1-difluoroethane and heavy component waste liquid, wherein the reflux light components are combined with the 1-chloro-1,1-difluoroethane coming out of the top of the deheaving treatment unit C4 through the reflux light component outlet and collected as the main product R142b, and 2-chloro-1,1-difluoroethane is extracted through the side line outlet of the separation and recovery unit C5 as a by-product R142, thereby realizing the value-added reuse of resources and reducing resource waste, and the heavy component waste liquid is transported to the incineration device through the lower outlet of the separation and recovery unit C5.

[0092] The purity of the main product 1-chloro-1,1-difluoroethane (R142b) obtained by the treatment in this example is 99.9%, and the purity of the by-product 2-chloro-1,1-difluoroethane (R142) reaches 95%.

[0093] Example 2

[0094] The device used in this example is consistent with that in Example 1, and the separation and purification method provided in this example is basically consistent with that in Example 1, except that:

[0095] In step 1), the temperature of the deacidification treatment is 30°C and the pressure is 0.3 MPa, and the temperature of the dehydration treatment is 50°C and the pressure is 0.3 MPa;

[0096] In step 2), the pressure of the pressurization treatment is 4 MPa, the temperature is 220°C, and the pressure of the heat exchange liquefaction treatment is 150°C;

[0097] In step 3), the tower top temperature for light removal treatment is 100°C and the tower top pressure is 2.0MPa, and the tower top temperature for heavy removal treatment is 85°C and the tower top pressure is 1.0MPa;

[0098] In step 4), the top temperature of the tower for separation and recovery is 45° C., and the top pressure is 1.0 MPa.

[0099] The purity of the main product 1-chloro-1,1-difluoroethane (R142b) obtained by the treatment in this example is 99.7%, and the purity of the by-product 2-chloro-1,1-difluoroethane (R142) reaches 94.5%.

[0100] Comparative Example 1

[0101] The device used in this comparative example is as follows Figure 2 As shown, it includes a water washing unit X1, an alkali washing unit X2, a freeze dehydration unit H3, a pressurized treatment unit Z1, a condensation unit H2, a flash treatment unit Y1, a light removal treatment unit X3, a heavy removal treatment unit X4, and a separation and recovery unit X5.

[0102] Among them, the alkali washing unit X1 includes an inlet for the mixture to be separated, the top outlet of the water washing unit X1 is connected to the bottom inlet of the alkali washing unit X2, the top outlet of the alkali washing unit X2 is connected to the inlet of the freeze-dehydration unit H3, the outlet of the freeze-dehydration unit H3 is connected to the inlet of the pressurizing unit Z1, the outlet of the pressurizing unit Z1 is connected to the inlet of the condensation unit H2, the outlet of the condensation unit H2 is connected to the inlet of the flash unit Y1, the bottom liquid phase outlet of the flash unit Y1 is connected to the inlet of the light removal unit X3, the bottom outlet of the light removal unit X3 is connected to the inlet of the heavy removal unit X4, the bottom outlet of the heavy removal unit X4 is connected to the inlet of the separation and recovery unit X5, and the reflux light component outlet of the separation unit X5 is connected to the inlet of the pressurizing unit Z1.

[0103] The separation and purification method provided in this comparative example comprises the following steps:

[0104] 1. The mixture to be separated from the reaction liquid of the photochlorination reaction first enters the water washing unit X1 to absorb the acid gases including hydrogen chloride, hydrogen fluoride and chlorine in the feed mixture through water at 40°C and 0.2MPa pressure, and then enters the alkali washing unit X1 to neutralize the remaining acid gases;

[0105] 2. In the alkaline washing unit X1, the mixture to be separated is fully contacted with the alkaline solution in reverse to obtain a deacidified intermediate. The deacidified intermediate enters the freeze dehydration unit H3 through the deacidified intermediate outlet of the alkaline washing unit X2 and the inlet of the freeze dehydration unit H3, and is cooled to 5° C. to obtain a first intermediate.

[0106] The alkaline solution in the deacidification treatment unit X1 is a 32% sodium hydroxide solution.

[0107] 3. The first intermediate enters the pressurizing unit Z1 through the outlet of the freeze-dehydration treatment unit H3 and the inlet of the pressurizing unit Z1, and then is pressurized to 1.3MPa and 120°C in the pressurizing treatment unit Z1 to obtain a pressurized mixture to be separated. The mixture to be separated then enters the condensing unit H2, condenses to 1.2MPa, and undergoes gas-liquid conversion treatment at 45°C to obtain a liquid phase mixture to be separated. The flash treatment unit Y1 performs flash treatment at a temperature of 45°C and a pressure of 1.2MPa to obtain a non-condensable gas and a liquid intermediate, and the non-condensable gas is transported to the incineration device through the gas phase outlet.

[0108] 4. The liquid intermediate enters the light removal treatment unit X3 through the liquid phase outlet of the flash treatment unit Y1 and the inlet of the light removal treatment unit X3, and is subjected to light removal treatment at a temperature of 55° C. and a pressure of 1.1 MPa. Difluoroethane is obtained at the top of the tower and a target mixed liquid is obtained at the bottom of the tower. Difluoroethane is transported to the raw material inlet of the photochlorination reaction unit through the upper gas phase outlet to circulate and participate in the photochlorination reaction. The target mixed liquid enters the heavy removal treatment unit X4 through the liquid phase outlet of the light removal treatment unit X3 and the inlet of the heavy removal treatment unit X4, and is subjected to heavy removal treatment at a temperature of 51° C. and a pressure of 0.7 MPa, and a top reflux ratio of 4.6, and 1-chloro-1,1-difluoroethane product is obtained at the top of the tower. 1-chloro-1,1-difluoroethane is output through the 1-chloro-1,1-difluoroethane outlet at the top of the heavy removal treatment unit X4 and is collected. Different from the present invention, the bottom reboiler of this tower is completely heated by steam.

[0109] 5. The heavy component obtained by the deheaving treatment in the deheaving treatment unit X4 enters the separation and recovery unit X5 through the outlet of the heavy component to be separated and the inlet of the heavy component to be separated of the separation and recovery unit X5, and is separated and recovered at a temperature of 95°C and a pressure of 0.5MPa to obtain a reflux light component and a heavy component waste liquid, wherein the reflux light component is circulated through the outlet of the reflux light component and the inlet of the pressurized treatment unit to participate in the separation and purification treatment, and the heavy component waste liquid is transported to the incineration device through the lower outlet of the separation and recovery unit X5.

[0110] The purity of 1-chloro-1,1-difluoroethane obtained by the treatment in this comparative example is 99.9%.

[0111] Compared with Example 1 of the present invention, although the purity of the final product of the comparative example is relatively close, due to differences in the process and operating conditions, a portion of the 1-chloro-1,1-difluoroethane in the comparative example is sent to the incineration system as a non-condensable gas at the top outlet of the flash unit Y1, resulting in partial product loss, and the by-product 2-chloro-1,1-difluoroethane is not recovered and is directly sent to the incineration system, and resource utilization is not sufficient. In addition, the gas at the top of the recovery separation unit X5 is sent to the inlet of the pressurizing unit Z1, resulting in repeated pressurization. The de-weighting unit X4 completely adopts steam heating, and the energy consumption is relatively high. Finally, the present invention simplifies the process by combining the alkali washing and dehydration units through solid alkali absorption.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for separating and purifying 1-chloro-1,1-difluoroethane, characterized in that: The following steps are involved: 1) performing a deacidification-dehydration treatment on a mixture to be separated to obtain a first intermediate; the mixture to be separated comprises 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane, 1,1-difluoroethane, and hydrogen chloride; 2) subjecting the first intermediate to a pressurization treatment and a heat exchange liquefaction treatment to obtain a liquid intermediate; 3) The liquid intermediate is subjected to light removal treatment and heavy removal treatment in sequence to obtain the 1-chloro-1,1-difluoroethane; wherein the heat exchange medium of the heat exchange liquefaction treatment is derived from the reflux heavy component of the heavy removal treatment.

2. The separation and purification method according to claim 1, characterized in that The mixture to be separated comes from the reaction liquid of the photochlorination reaction.

3. The separation and purification method according to claim 2, characterized in that In the light removal treatment, the light components removed include 1,1-difluoroethane.

4. The separation and purification method according to any one of claims 1 to 3, characterized in that: In the de-heaving treatment, the removed heavy components include the heavy components to be separated; The heavy components to be separated are separated and recovered to obtain 1-chloro-1,1-difluoroethane, 2-chloro-1,1-difluoroethane and heavy component waste liquid respectively.

5. The separation and purification method according to any one of claims 1 to 4, characterized in that: The deacidification-dehydration treatment includes deacidification treatment and dehydration treatment in sequence; wherein, The deacidification treatment comprises contacting the mixture to be separated with water in reverse at 30° C. to 80° C. and a pressure of 0.01 MPa to 0.8 MPa to obtain a deacidification intermediate; The dehydration treatment includes contacting the deacidified intermediate with a solid alkaline substance at 10° C. to 80° C. and a pressure of 0.01 MPa to 1.0 MPa to obtain the first intermediate.

6. The separation and purification method according to claim 4, characterized in that: The pressure of the pressurization treatment is 1.5MPa-4MPa, and the temperature is 120°C-220°C; And / or, the heat exchange liquefaction treatment has a pressure of 1.5 MPa to 4.0 MPa and a temperature of 60° C. to 200° C.; And / or, the tower top pressure of the light removal treatment is 0.5MPa-2.0MPa, the tower top temperature is 30°C-100°C, and the tower bottom temperature is 50°C-150°C; And / or, the tower top pressure of the deweighting treatment is 0.5MPa-1.0MPa, the tower top temperature is 30°C-100°C, and the tower bottom temperature is 50°C-150°C; And / or, the tower top pressure of the separation and recovery is 0.1MPa-1.0MPa, the tower top temperature is 0°C-70°C, and the tower bottom temperature is 40°C-100°C.

7. A device for separating and purifying 1-chloro-1,1-difluoroethane, characterized in that: The device is used to perform the separation and purification method according to any one of claims 1 to 6; It includes a deacidification-dehydration treatment unit, a pressurization treatment unit, a heat exchange liquefaction treatment unit, a light removal treatment unit, and a heavy removal treatment unit; The deacidification-dehydration treatment unit comprises an inlet for receiving a mixture to be separated, a first intermediate outlet of the deacidification-dehydration treatment unit is communicated with the inlet of the pressurization treatment unit, the outlet of the pressurization treatment unit is communicated with the heat medium inlet of the heat exchange liquefaction treatment unit, the heat medium outlet of the heat exchange liquefaction treatment unit is communicated with the inlet of the light removal treatment unit, the liquid phase outlet of the light removal treatment unit is communicated with the liquid phase inlet of the heavy removal treatment unit, and the gas phase outlet of the heavy removal treatment unit is used to output the 1-chloro-1,1-difluoroethane; The reflux heavy component outlet of the de-weighting unit is communicated with the cold medium inlet of the heat exchange liquefaction unit, and the cold medium outlet of the heat exchange liquefaction unit is communicated with the reflux heavy component inlet of the de-weighting unit.

8. The device according to claim 7, characterized in that Also includes a photochlorination reaction unit, The light component outlet of the light component removal treatment unit is communicated with the raw material inlet of the photochlorination reaction unit.

9. The device according to claim 7 or 8, characterized in that Also includes a separation recovery unit; The separation and recovery unit includes a top reflux light component outlet and a side line 2-chloro-1,1-difluoroethane byproduct production outlet; The outlet of the heavy component to be separated of the de-weighting processing unit is communicated with the inlet of the heavy component to be separated of the separation and recovery unit.

10. The device according to any one of claims 7 to 9, characterized in that: The deacidification-dehydration treatment unit includes a deacidification treatment unit and a dehydration treatment unit; The deacidification intermediate outlet of the deacidification treatment unit is connected to the inlet of the dehydration treatment unit; The inlet of the mixture to be separated is arranged in the deacidification treatment unit, and the outlet of the first intermediate is arranged in the dehydration treatment unit.

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