TWI243808B - Production of 1,2-dichloroethane - Google Patents

Abstract

A process and an apparatus are described for the preparation of 1,2-dichloroethane by reacting ethene with hydrogen chloride and an oxygen-containing gas in an oxychlorination reactor by means of a fluidised bed with formation of a reaction gas, wherein the reactor gas is filtered outside the oxychlorination reactor by means of at least one filter candle.

Description

1243808 Case No. 9Π18063 Amendment (1) V. Description of the invention [Technical field to which the invention belongs] The present invention relates to a process for manufacturing 1,2-dichloroethane and its equipment, which utilizes gas oxidation on ethylene. The reaction is generated to produce a process of 1,2-digasethane and its equipment. During the preparation process, the 1,2-dichloroethane is gas-oxidized in a fluidized bed (f 1 uidizedbed). In the reactor, ethylene is reacted with hydrogen chloride and oxygen-containing gas.

[Prior art] Press, using chlorine oxidation (ο X ych 1 〇rinati ο η), to react with a dilute type (in the present invention, for example, ethylene) with hydrogen chloride and an oxygen-containing gas, such as oxygen or air to generate a saturated gas alkane [ In the present invention, for example, the production of 1,2-dichloroethane (Ethylene dichloridel, 2-dichloroethanej hereinafter referred to as EDC)] is a well-known technique known to those in the industry. This reaction is basically carried out according to the following reaction formula: C2H4 + 2HC 1 + 1/2 0 2 — C1-CH2-CH2-C1 + Η 20 However, the water of the by-product is easy to react with the unreacted starting reactant ( That is, hydrogenated gas) reacts to form hydrochloric acid. Because hydrochloric acid is highly corrosive, it is necessary to use a reaction device composed of a relatively anti-corrosive material to perform the above-mentioned reaction to prepare an alkane. In contrast, this also increases manufacturing costs

Page 6 1243808 _Case No. 9Π18063_ 年月 日 _Character_V. Description of the invention (2) There are many. Incidentally, the above EDC preparation is usually carried out in the presence of a catalyst. Taking the reaction equipment on the industrial mass production scale as an example, the catalyst is copper chloride carried on an alumina support, and the above-mentioned chlorine oxidation reaction is performed in the form of a fluidized bed. In the conventional reaction in the form of an industrial fluidized bed, part of the catalyst is separated by a plurality of cyclone separators arranged next to one another and separated by an upper part of the reactor which is oxidized by chlorine, and by a plurality of cyclone separators arranged next to each other. The separation leaves, so that most of the main part of the catalyst can remain in the reactor. In addition, a small part of the so-called catalyst chips will enter the reaction gas generated from the reactor and leave the reactor, and then enter the 1,2-dichloroethane gas condensing section, where the catalyst chips will be mixed again. separate from. For example, German patent DE 4 1 3 2 0 3 0 (Germa η Offenlegungsschrift DE41 32030) discloses a method that can be used to remove catalyst debris, which is applied to the preparation of 1,2-digas ethane by a fluidized bed chlorine oxidation process. During the process, catalyst chips are generated in the reaction zone. This catalyst chip is discharged from the reaction zone together with the crude EDC gas stream. According to this patent, the catalyst chips carried out from the reaction zone are separated from the crude EDC gas stream after drying in a clean zone under dry conditions. In a preferred embodiment, a dust separator or an electrostatic filter is used as the clean area to achieve the purpose of separating the catalyst chips from the crude EDC gas stream. In the case of a dust separator, the filter bag method can be used together with compressed circulating air, so that the catalyst dust separated from the clean zone can be prevented from contacting the adsorbed reaction products set in the downstream adsorption zone. Although this method can avoid the waste water production of heavy metals and inorganic mud

Page 7 1243808 _Serial No. 91118063 — _ year month _g__correction _____ V. Description of the invention (3) However, the separated catalyst dust can no longer be recycled and must be used as an industry in an appropriate way Waste cleaning. In addition, this method will also lead to a considerable number of summer dioxin (p0lyChi〇rinated (1 丄 61 61120 (1 丨 0 \: [11, hereinafter referred to as 1) (: 1) 1)) and polychlorinated dibenzofuran , Hereinafter referred to as PCDF) is discharged into the environment in the form of wastewater and causes pollution. Actual use also proves that this method is very cumbersome and difficult to handle, requires high standards of equipment, takes up a lot of space, and therefore requires a lot of cost. DE-A- 1 9 7 5 3 1 6 5 discloses another process for preparing 1, 2-gaseous ethane by gas oxidation, wherein ethylene is in a fluidized bed with copper-containing catalyst. Reacts with hydrogen chloride and oxygen-containing gases. In this case, the catalyst is maintained in the reactor by extremely fine filtering so that the reaction gas generated by the reactor will not carry the catalyst. The catalystless reaction gas is then introduced into a quenching officer 'and condensed and concentrated in a manner well known to those skilled in the art. The shortcomings of this case are that ... due to the filtration, the reactor gradually accumulates extremely fine catalyst particles as the reaction time lengthens. This will cause the flow characteristics of the catalyst bed to be destroyed and the heat conduction characteristics in the reactor to be poor. In addition, especially because of the lack of pre-separation of the reaction cyclone, the dust load in the reaction gas produced by this method is very high. Due to the need to take into account the high proportion of particulate components', the filtration area is increased. In addition, the method described in DE 丨 9 7 5 3 丨 6 5 is only applicable to new systems, and requires complex means before it can be applied to existing manufacturing systems. In the 1986 edition of the U1lmann Encyclopedia of Industrial Chemistry, Vol. 1, p. 269 (U1lmann ’s Encyclopedia 〇f industrial

Page 8 1243808 _ Case No. 9Π18063_ Year Month Revision _ V. Description of the invention (4)

Chemistry, Vol. A6, 1986, ρ · 269) further mentions a conventional method, in which the thermal reaction gas discharged from the fluidized bed is produced in the same way as EDC gas and water due to the use of the chloridation method. Contains unreacted hydrogenated hydrogen gas, which is further quenched with an aqueous solution. In this method, unseparated catalyst chips are washed out together with unreacted hydrogen chloride gas. It may be possible to use both external water and water produced during the reaction as a flushing liquid. The EDC gas is quenched with water, and then distilled and condensed. The disadvantage of this method is that because the quenched wastewater contains catalyst dust, it requires a tedious treatment step before it can be discharged. It can be seen that all the previous cases of using fluidized beds have shortcomings, and the shortcomings may be that PCDD and PCDF may be generated, or that the existing system needs to be improved in a complicated manner to achieve higher catalysts. Separation rate. [Summary of the Invention] The main object of the present invention is to provide a process and equipment for producing 1,2-digasethane, so as to prepare 1,2-dichloroethane, so that the catalyst chips generated during the reaction can be used. It is removed at the lowest cost, while achieving as high a degree of catalyst separation as possible. _ Another object of the present invention is to provide a device for manufacturing 1,2-dichloroethane, which can achieve sufficient separation of PCDD and PCDF from the reaction gas with a minimum cost. The above object can be achieved by filtering the reaction gas outside the reactor using chlorine oxidation mentioned at the beginning, and at least one filter rod is required.

Page 9 1243808 _Case No. 9118063_ Year Month Amendment _ V. Description of the Invention (5) [Embodiment] When the crude raw gas stream of 1,2-dichloroethane is filtered using a filter rod under general conditions, we It was surprisingly found that it was fully qualified for clean reactive gases, while at the same time possessing high chemical inertness (corrosion resistance). This high anti-corrosion ability is unpredictable by those in the industry, because the filter rod system has a large filtering area, and the corrosive mixed gas system passes the filter and rod at a high temperature of at least 200 ° C. In a preferred embodiment of the present invention, the filter rod contains at least one ceramic material as a filter material, and / or at least one sintered metal powder and / or high-grade steel wire (1.45 7 1 or equivalent material) Or other suitable alloys. For example, the filter rod may be a commercially available alloy with names such as RINCONEL, RM0NEL, and / or RHASTELL0Y. Similarly, the ceramic material contained in the filter rod may be used if it has an appropriate average pore size.

Page 10 1243808 _Case No. 91118063_ Year Month Amendment_ V. Description of the invention (6) When these filter materials are used, PCDD and PCDF can be separated from the reaction gas. I was surprised to find that PCDD and PCDF have very good separation performance. The unexpected effect is due to the fact that the materials used to transport these compounds are very complex and most have not been studied in detail. Especially when the filter material of the filter rod has an average pore diameter of 15 micrometers or less, it has the effect of separating PCDD and PCDF. A better effect is an average pore diameter of 8 micrometers or less. A better average pore diameter is 5 micrometers or less. Even less than or equal to 1 micron, so that the separation of PCDD and PCDF can be greatly improved. Smaller average pore size limits, such as 0.01 micron, 0.01 micron, 0.01 micron, and 0.1 micron and 0.5 micron can be used. From this, it can be known that the average pore diameter of the filter material referred to in this case may be between 0.001 and 0.5 microns. It is known to use glass fiber as a filter material, but it cannot achieve the purpose of separating PCDD and PCDF. In addition, when the reaction gas is directly condensed and concentrated, that is, without being subjected to a quenching step in the middle, almost all of the residual PCDD and PCDF can be passed into the organic phase, leaving almost no such substances in the wastewater. Since it is now possible to use the simplest way, a filter element equipped with at least one filter rod to achieve high separation efficiency, especially for PCDD and PCDF, the content of such compounds in wastewater can be almost completely removed. The present invention also solves the problem of extremely fine particles settling in the filter housing by using the gas flow stroke in the following filter to block the filter. The stroke includes that the velocity vector in the direction of gravity is greater than 0, where the velocity vector is derived from the deposition rate of the catalyst particles and the gas flow rate (circulating gas, 1, 2-dichloroethane, and process water), which is derived from the catalyst Particle deposition rate

Page 11 1243808 _Case No. 91118063 __ Year Month Day Amendment _ V. Description of the invention (7) and the gas flow rate (circulating gas, 1, 2-dichloroethane and process water) are greater than 0. As mentioned above, in this case, in some applications, the reaction gas can be directly condensed and concentrated after fine filtration, without the need to go through the quenching process used by conventional technologies, thus saving equipment (ie, quenching tower) , And the cost of the land occupied by the equipment. In terms of manufacturing conditions, especially described in the German case Aus 1 egeschrift 1 5 1 8 9 3 1 and the German patent specification i 4 6 8 4 8 9 can be applied to this method Invented to improve. According to a preferred embodiment of the present invention, the pressure of the reaction gas before leaving the chlorine oxidation reaction f 'before entering the filter rod is preferably between 丨 and 6 bar, and the preferred implementation state is 3.5 bar. . The temperature of the reaction gas passing through the bar should be between 200 and 250 ° C, which is more than 22 °: The better result can be the rate of deposition from the catalyst particles. Although the velocity vector in the direction of gravity includes gravity, its gas burning and process water IV / gas flow rate (circulating gas, 1, 2-2 after filtration) , And the temple corpse is then directly condensed and concentrated. The gas can be quenched or cooled according to the degree of purification, and the reaction equipment can be constructed with a simple structure. This is ::: The media does not need to pass through, such as DEm 5 3 1 The content of pC]) D and pCDF in the gas treated by the complex equipment described in the case 65

Page 12 1243808 _Case No. 91118063_year month_ίΜι_ V. Description of the invention (8) less than 0.1 micrograms / product produced by the oxidation reaction of chlorine (per metric ton). In the gas treated by the method of the present invention, the separation rate of the catalyst particles can reach more than 99.9%. Since the filtration of the present invention is performed with a filter rod outside the reactor, the structure is simple, so that the existing chlorine oxidation reactor with a fluidized bed can be directly modified and constructed in the most space-saving manner. Provides high operational reliability, so preparation units can also be omitted. Because the present invention uses a filter rod that is hardly worn, besides that the particles can be smoothly discharged according to the stroke of the method of the present invention, it also saves tedious maintenance work. In order to optimize the process of the present invention, the reactor for preparing 1,2-dichloroethane has a fluidized bed and is provided with an inlet for supplying hydrogen chloride and an oxygen-containing gas, respectively, so that the gas is directly guided to the reaction These air inlets are provided with porous ventilation packings. In addition, when ethylene and circulating gas are introduced into the reactor through a disk body made of a porous, air-permeable material, or the disk body has a porous, air-permeable filling material, it can help the fluidized bed shaper. Among them, the construction of the air inlet can be selected, for example, from the constructor described in DEI 9 9 0 3 3 3 5A1. A preferred embodiment of the 1,2-digas ethane device according to the present invention (as shown in the first figure), and the process of manufacturing the 1,2-digas ethane according to the present invention is described in detail in the first figure. Bottom: First, the preheated starting materials, that is, hydrogen chloride and oxygen,

Page 13 1243808 Case No. 91118063 __η Amendment V. Description of the invention (9): The reaction space of the reactor 2 conducts the two-oxidation oxidation reactor 3, which is the same as the current day, and the reactor 2 is transported by the eunuch 2, after the preheating cycle Gas and ethylene are introduced into the gas oxidation reactor. The catalyst in inverted port 3 is not shown in the figure. 1 '2-dichloroethane is used to burn the crude raw gas, process water, f, and circulating gas through the cyclone separator 4 to leave the reactor 3 and enter the filtered state 6'. The filter 6 is provided with a plurality of filter rods 6 丄. Extremely fine catalyst dust is separated here and discharged through the output pipe 7 'through the conveying pipe 5, the backwash gas that has been preheated to clean the filter element in the filter 6 is introduced into the filter 6. 1,2-dichloroethane 、 =, gas, process water, and circulating gas are introduced into the conveying pipe 8, I t 1 order, 9 in rotation, among which 1, 2-dichloroethane Gas and water 7 = H spin into liquid evil. The liquid 1, 2 dichloroethane and water mixed liquid ^^ = 10 is separated from the circulating gas, and is sent through the pipe 12 to be treated. The circulating gas then returns to the inlet of the circulating gas compressor via the conveying pipe 11 again. Tian 铷 yi s 丄 1 倨 倨 倨 1 r ft equipped with a fluidized bed gas oxidation reactor using copper chloride in the catalyst to prepare 1, 2 ~ dichloroethane. Chlorine oxidation is performed under ordinary operating conditions that are well known to those skilled in the art, so the details will not be repeated. After this = Γ-chlorine oxidation reactor, the reaction gas (500Nm3 / h) flows from 200 to 25 fields. The clean area is operated in a dry state and the temperature is in a good state. 3Compare / Gui f 1 State Eight is away ^), I force is between 1 and 6 bar (Compared with grains, also known as the pull-out session 'L: θ ΐThe catalyst dust particles contained in the breast are the catalyst The genus ~. After this treatment, the catalyst is almost

1243808 _ Case No. 91118063_ Year Month Date _ Charm _ V. Description of the invention (10) Completely separated. The filter is composed of 8 filter rods, and the filter rod is composed of 3 1 6 S stainless steel. These 8 filter rods are periodically backwash cleaned with automatic valve control. A pre-heated nitrogen gas with a pressure of 8 bar is used here as a backwash gas. The fine catalyst dust separated by the filter is removed once a day through the outlet. The travel of the reaction gas is the velocity vector in the direction of gravity, which is derived from the catalyst particle deposition rate and the gas flow rate (circulating gas, 1,2-dichloroethane, and process water), and is greater than 0. This ensures optimum fine dust precipitation. _ The reaction gas with almost no catalyst dust has a temperature of 200 to 250 ° C, and the preferred implementation state is 220 ° C, which is then transported to the condenser through a pipeline, and 1,2 — Dichloroethane gas condenses with process water. The condensed liquid is separated from the circulating gas in the separator. The 1,2-digas ethane / water mixed liquid can be further transported to the separation tank through another conveying pipe, where the water is separated from the 1,2-dichloroethane. The following table shows the measured concentrations of dioxin PCDD and furan PCDF in wastewater produced by oxidizing chlorine. _

Page 15 1243808 _Case No. 91118063_ year, month, day, amendment V. Description of the invention (11)

Non-reduced fiber sintered metal legs (stainless steel) with an average pore size of less than 5 microns. According to NATO / CCMS, the volume of chlorine oxygen per ton of micrograms is 5 4.5 < 0.1 PCDD / PCDF TEQ. From the results in the table above, it can be known that the process of the invention Compared with filter rods using conventional glass fiber, the PCDD and PCDF content of the process gas filtered through a filter rod with a specific average pore size can be reduced by about 9 7%. The degree of separation of catalyst particles can reach more than 99.9%. Therefore, the PCDD and PCDF content in the wastewater can be greatly reduced, and therefore, large savings can be achieved.

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Page 17 1243808 Case No. 91Π8063 Amendment Brief Description of Schematic Illustration Schematic · The equipment is not intended to be finished with dichloroethane. The first figure is the manufacture of the present invention.

1 Tube 7 m Outlet tube 2 Tube 8 8 μ μ Tube 3 Gas oxidation reactor 9 Condenser 4 Cyclone separator 1 0 Feed tube 5 Feed tube 1 1 、 / Tube 6 Filter 1 2 Feed tube 6 1 Filter Stick Page 18

Claims (1)

1243808 _Case No. 91118063_Amended in January / August 6, Application scope 1 · A process for manufacturing 1,2-dichloroethane, which is produced by reacting ethylene with hydrogen chloride and oxygen-containing gas in a chlorine oxidation reactor A reaction gas is produced, which is characterized in that the reaction gas needs to be filtered by at least one filter rod outside the chlorine oxidation reactor. 2. The process for preparing 1,2-dichloroethane as described in item 1 of the scope of the patent application, wherein the filter rod includes at least one filtered ceramic material and / or at least one sintered metal powder and / or high-grade steel wire (Model 1. 4 5 7 1) or alloy. 3. The process of manufacturing 1,2-digasethane as described in item 2 of the scope of the patent application, wherein the filter material in the filter rod has an average pore diameter of from 0. 0 0 1 micrometer to 15 micrometers. 4 · The process of manufacturing 1,2-digas ethane as described in item 2 of the scope of the patent application, wherein the filter material in the filter rod has an average pore diameter of 0 to 0 1 micrometer to 8 micrometers. 5 · The process for manufacturing 1,2-digas ethane as described in item 2 of the scope of the patent application, wherein the filter material in the filter rod has an average pore diameter of from 0 to 0 micron to 5 micrometers. 6. The process for manufacturing 1,2-dichloroethane as described in item 1 of the scope of the patent application, wherein the pressure of the reaction gas flowing through the filter rod is between 1 and 6 bar. 7 · The process of manufacturing 1,2-dichloroethane as described in item 1 of the scope of the patent application, wherein the temperature of the reaction gas flowing through the filter rod is between 200 and 250 ° C. 8 · Manufacturing 1,2-dichloroethane as described in item 1 of the scope of patent application Page 19 1243808 _ Case No. 91118063_ year month and month amendment _ 6. The process of applying for a patent, where the stroke of the reaction gas is the velocity vector in the direction of gravity, and the velocity vector is greater than 0, where the velocity vector is determined by the catalyst The particle deposition rate and the gas flow rate (circulating gas, 1,2-digas ethane and process water) are derived. 9 · The process for producing 1,2-dichloroethane as described in item 1 of the scope of the patent application, wherein the reaction gas is filtered, and then entered into a quench tube or directly condensed and concentrated. 1 0 · The manufacturing process of 1,2-digas ethane as described in item 1 of the scope of patent application, wherein the content of dioxin and furan in the wastewater generated by the oxidation of the fluidized bed is less than 0.1 micrograms / Chloro-oxidation reaction_ Products produced (per kiloton). 1 1 · The process of manufacturing 1,2-dichloroethane as described in item 1 of the scope of patent application, wherein the reaction gas contains catalyst particles, and the degree of separation of the catalyst particles can reach 99.9%. the above. 1 2 · A kind of equipment for manufacturing 1,2-dichloroethane, which has a chlorine oxidation reactor and a filter to react ethylene, hydrogen chloride and oxygen-containing gas, characterized in that the filter has at least one A filter rod, the filter being arranged outside the chlorination reactor. 1 3 · The device for manufacturing 1,2-dichlorog ethane as described in item 12 of the scope of patent application, wherein the filter rod includes at least one filtered ceramic material and / or at least one sintered metal powder and / or high Grade steel wire (type 1 · 45 7 1) or alloy. 1 4 · The equipment for manufacturing 1,2-dichloroethane as described in item 12 of the scope of the patent application, wherein the filter material of the filter rod has a diameter of 0. 0 0 0 1 μm to 1 5 Page 20 1243808 _Case No. 91118063 _ Year Month Amendment_ Sixth, patent application scope The average pore size in microns. 1 5 · The equipment for manufacturing 1,2-dichloroethane as described in item 12 of the scope of the patent application, wherein the filter material of the filter rod has an average pore diameter of 1 to 8 microns. 16 · The equipment for manufacturing 1, 2-two-gas and second-boiler as described in item 12 of the scope of the patent application, wherein the filter material of the filter rod has an average pore diameter of 1 to 5 micrometers. 1 7 · The equipment for manufacturing 1,2-digas as described in item 12 of the scope of patent application, wherein the chlorination reactor is further provided with a hydrogen chloride gas inlet and / or an oxygen-containing gas inlet It is a direct introduction of hydrogen chloride and / or oxygen gas into a fluidized bed in the chlorination reactor. 1 8 · The equipment for manufacturing 1,2-digas ethane as described in item 17 of the scope of patent application, wherein the hydrogen chloride gas inlet and / or the oxygen-containing gas inlet is provided with a porous and breathable filler. 1 9 · The equipment for manufacturing 1,2-digas as described in item 12 of the scope of patent application, wherein the gas oxidation reactor contains a circulating gas and / or an ethylene Panel import. 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