Preparation method of ethyl tert-butyl ether

Abstract

The invention provides an ethyl tert-butyl ether preparation method, which comprises: carrying out at least two-stage etherification reaction on a C4 raw material and ethanol to obtain a pre-product; carrying out reactive distillation on the pre-product, wherein the reactive distillation comprises stripping treatment and reactive distillation treatment; the pre-product is subjected to stripping treatment, an ethyl tert-butyl ether product is extracted, and a C4 and ethanol mixture obtained through separation is subjected to reactive distillation treatment; ethyl tert-butyl ether obtained through reactive distillation treatment is returned for stripping treatment, and C4 and ethanol obtained through reactive distillation separation are subjected to ethanol recovery treatment. According to the preparation method, stripping of reactive distillation and reactive distillation are carried out separately, and ethyl tert-butyl ether in a pre-product and unreacted C4 and ethanol are separated before reactive distillation, so that the raw material conversion rate of the reactive distillation step is greatly improved, and the overall conversion rate of isobutene is further improved; and meanwhile, the purity of the ethyl tert-butyl ether product extracted by reaction distillation is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of chemical synthesis process, and relates to a preparation method of ethyl tert-butyl ether. BACKGROUND

[0002] Ethyl tert-butyl ether (ETBE) is an important chemical product, mainly used as an oxygenated additive for gasoline, which can significantly increase the octane rating (RON about 111), reduce engine knock, and lower the emission of CO and unburned hydrocarbons in exhaust gas. Compared with the traditional methyl tert-butyl ether (MTBE), ETBE has better environmental performance, stronger biodegradability, and lower risk of groundwater pollution, so it is widely promoted. In addition, ETBE can be used as an organic solvent in the pharmaceutical, fine chemical and polymer industries, and is suitable for organic synthesis, extraction and cleaning processes. In the fuel field, ETBE is often mixed with bioethanol for use, which improves the stability of fuel and meets the renewable energy standard. Although the trend of directly using bioethanol has an impact on its market growth, ETBE still maintains an important position in the field of green fuel and high-performance gasoline additives due to its high octane rating, low volatility and environmental friendly characteristics.

[0003] The industrial synthesis of ethyl tert-butyl ether (ETBE) is mainly based on the acid-catalyzed etherification reaction of ethanol with isobutene, and the core step is to generate the target product through nucleophilic substitution. The specific process is as follows: under the action of an acid catalyst (such as sulfuric acid, sulfonic acid type ion exchange resin or heteropoly acid), ethanol (CH3CH2OH) and isobutene ((CH3)2C=CH2) undergo addition reaction in liquid or gas phase to generate ETBE (CH3CH2O-C(CH3)3). The reaction temperature is usually controlled at 50-100℃, and the pressure is 0.5-2MPa to improve the solubility of isobutene in the liquid phase. This reaction follows the SN1 mechanism, and isobutene forms a tertiary carbonium ion intermediate under the action of the acid catalyst, and then the oxygen atom of ethanol attacks to form an ether bond. In order to improve the yield, the molar ratio of raw materials (slightly excess of ethanol) needs to be controlled, and a continuous reaction-distillation coupling process is adopted to separate the product in time to break the equilibrium limitation. The selection of catalyst directly affects the environmental performance: solid acid (such as resin) can reduce equipment corrosion and wastewater discharge, and is easy to recover. However, in the prior art, when carbon four is used as the raw material for synthesizing ETBE, the conversion rate of isobutene in carbon four is low, the product purity is low, and further purification treatment of the product is needed. SUMMARY

[0004] In order to solve the technical problems in the prior art, the application provides a preparation method of ethyl tert-butyl ether, which separates the stripping of reaction distillation and the reaction rectification, separates the ethyl tert-butyl ether and unreacted carbon four and ethanol in the pre-product before the reaction rectification, greatly improves the raw material conversion rate of the reaction rectification stage, further improves the overall conversion rate of isobutylene, and improves the purity of the ethyl tert-butyl ether product extracted by the reaction distillation.

[0005] In order to achieve the above technical effects, the application adopts the following technical solutions:

[0006] The application provides a preparation method of ethyl tert-butyl ether, which comprises the following steps:

[0007] The carbon four raw material is subjected to at least two-stage etherification reaction with ethanol to obtain a pre-product;

[0008] The pre-product is subjected to reaction distillation, and the reaction distillation comprises stripping treatment and reaction rectification treatment; the pre-product is subjected to the stripping treatment to extract the ethyl tert-butyl ether product, and the obtained carbon four and ethanol mixture is subjected to the reaction rectification treatment; the ethyl tert-butyl ether obtained by the reaction rectification treatment is returned to the stripping treatment, and the carbon four and ethanol obtained by the reaction rectification are subjected to ethanol recovery treatment.

[0009] As a preferred technical solution of the application, the etherification reaction comprises sequentially performed first-stage etherification reaction, second-stage etherification reaction and third-stage etherification reaction.

[0010] As a preferred technical solution of the application, the temperature of the first-stage etherification reaction is 40-55 DEG C, and the pressure is 1.3-1.4 MPa.

[0011] And / or, the temperature of the second-stage etherification reaction is 45-65 DEG C, and the pressure is 1.15-1.25 MPa.

[0012] And / or, the temperature of the third-stage etherification reaction is 60-70 DEG C, and the pressure is 1.0-1.15 MPa.

[0013] And / or, the temperature of the third-stage etherification reaction is greater than the temperature of the second-stage etherification reaction, which is greater than the temperature of the first-stage etherification reaction.

[0014] As a preferred technical solution of the application, the alcohol-olefin ratio of the first-stage etherification reaction, the second-stage etherification reaction and the third-stage etherification reaction is independently 1.02-1.05, and the molar ratio is independently 1.02-1.05.

[0015] As a preferred technical solution of the application, the temperature of the ethyl tert-butyl ether product extracted by the stripping treatment is 135-140 DEG C.

[0016] And / or, the temperature of the carbon four and ethanol mixture obtained by the stripping treatment is 65-70 DEG C.

[0017] As a preferred technical scheme of the present application, the temperature of the reaction rectification treatment is 60-70℃.

[0018] As a preferred technical scheme of the present application, ethanol is supplemented during the reaction rectification treatment to maintain the alcohol-alkene ratio in the reaction rectification treatment at 1.02-1.05 (molar ratio).

[0019] As a preferred technical scheme of the present application, the ethanol recovery treatment includes countercurrent extraction and ethanol separation performed in sequence.

[0020] As a preferred technical scheme of the present application, the extractant used in the countercurrent extraction is water.

[0021] As a preferred technical scheme of the present application, the ethanol separation includes separation of ethanol and extractant by distillation, the ethanol is recycled to the etherification reaction, and the extractant is recycled to the countercurrent extraction.

[0022] Compared with the prior art, the present application has at least the following beneficial effects:

[0023] The present application provides a preparation method of ethyl tert-butyl ether, which separates the stripping and reaction rectification of reaction distillation, separates the ethyl tert-butyl ether and unreacted carbon four and ethanol in the pre-product before the reaction rectification, greatly improves the raw material conversion rate of the reaction rectification stage, further improves the overall conversion rate of isobutylene, and improves the purity of the ethyl tert-butyl ether product extracted by the reaction distillation. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The device structure schematic diagram used in the preparation method of ethyl tert-butyl ether provided in the present application is shown.

[0025] In the figure: A-reaction unit, B1-stripping column, B2-reaction rectification column, C-ethanol separation unit.

[0026] The present application will be further described in detail below. However, the examples described below are only simple examples of the present application, and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims. DETAILED DESCRIPTION

[0027] The technical scheme of the present application will be further described below through a specific embodiment.

[0028] The present application provides a preparation method of ethyl tert-butyl ether, which includes:

[0029] The carbon four raw material is subjected to at least two-stage etherification reaction with ethanol to obtain a pre-product;

[0030] The pre-product is subjected to reaction distillation, which includes stripping treatment and reaction rectification treatment; the pre-product is subjected to stripping treatment to obtain ethyl tert-butyl ether product, and the separated carbon four and ethanol mixture is subjected to reaction rectification treatment; the ethyl tert-butyl ether obtained by reaction rectification treatment is returned to the stripping treatment, and the carbon four and ethanol obtained by reaction rectification separation are subjected to ethanol recovery treatment.

[0031] In one specific embodiment of the present application, the etherification reaction includes first-stage etherification reaction, second-stage etherification reaction and third-stage etherification reaction performed in sequence.

[0032] In one specific embodiment of the present application, the etherification reaction can also be performed in parallel with first-stage etherification reaction and second-stage etherification reaction, and the products of the two-stage reaction are combined to perform third-stage etherification reaction.

[0033] In one specific embodiment of the present application, the temperature of the first-stage etherification reaction is 40-55℃, and the pressure is 1.3-1.4MPa. The temperature of the reaction can be 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃ or 55℃, and the pressure of the reaction can be 1.3MPa, 1.31MPa, 1.32MPa, 1.33MPa, 1.34MPa, 1.35MPa, 1.36MPa, 1.37MPa, 1.38MPa, 1.39MPa or 1.4MPa, but not limited to the listed values, and other values not listed in the above ranges are also applicable.

[0034] In one specific embodiment of the present application, the temperature of the second-stage etherification reaction is 45-65℃, and the pressure is 1.15-1.25MPa. The temperature of the reaction can be 45℃, 48℃, 50℃, 52℃, 55℃, 58℃, 60℃, 62℃ or 65℃, and the pressure of the reaction can be 1.15MPa, 1.16MPa, 1.17MPa, 1.18MPa, 1.19MPa, 1.20MPa, 1.21MPa, 1.22MPa, 1.23MPa, 1.24MPa or 1.25MPa, but not limited to the listed values, and other values not listed in the above ranges are also applicable.

[0035] In one specific embodiment of the present application, the temperature of the third-stage etherification reaction is 60-70 DEG C, and the pressure is 1.0-1.15 MPa. The temperature of the reaction can be 60 DEG C, 61 DEG C, 62 DEG C, 63 DEG C, 64 DEG C, 65 DEG C, 66 DEG C, 67 DEG C, 68 DEG C, 69 DEG C, or 70 DEG C, and the pressure of the reaction can be 1.0 DEG C, 1.02 DEG C, 1.05 DEG C, 1.08 DEG C, 1.1 DEG C, 1.12 DEG C, or 1.15 DEG C, but is not limited to the listed values, and other values not listed in the above ranges are also applicable.

[0036] In one specific embodiment of the present application, the temperature of the third-stage etherification reaction is greater than the temperature of the second-stage etherification reaction, which is greater than the temperature of the first-stage etherification reaction. In the present application, when the third-stage etherification reaction is carried out in series, the reaction temperature increases with the number of stages, which on the one hand increases the conversion rate of isobutylene, and on the other hand reduces the generation of side reactions, thereby reducing the difficulty of separation of subsequent products and improving the purity of the products.

[0037] In one specific embodiment of the present application, the alcohol-olefin ratio of the first-stage etherification reaction, the second-stage etherification reaction, and the third-stage etherification reaction is independently 1.02-1.05, such as 1.02, 1.03, 1.04, or 1.05, but is not limited to the listed values, and other values not listed in the range are also applicable. In each stage of etherification reaction, the slight excess of ethanol is maintained by controlling the flow rate of the feed, so as to ensure that the etherification reaction proceeds in the positive direction of the reaction equilibrium, and at the same time, the continuous etherification reaction is carried out, and the reactants are continuously removed from the reaction system, which further promotes the reaction to proceed in the positive direction of the reaction equilibrium.

[0038] In one specific embodiment of the present application, the first-stage etherification reaction, the second-stage etherification reaction, and the third-stage etherification reaction are independently carried out in a reaction kettle, and the flow monitoring component and the temperature monitoring component can be arranged in each reaction kettle to ensure the stability of the alcohol-olefin ratio and the reaction temperature. The temperature can also be controlled by arranging an external circulation pipeline in the reaction kettle (heat exchange devices are arranged in the external circulation pipeline), which at the same time improves the heat and mass transfer efficiency in the reaction kettle and improves the reaction rate.

[0039] In one specific embodiment of the present application, the time of the first-stage etherification reaction, the second-stage etherification reaction, and the third-stage etherification reaction, i.e., the residence time in each reaction kettle, can be adjusted according to the product, and is not limited further herein.

[0040] In one specific embodiment of the present application, the temperature of the ethyl tert-butyl ether product obtained by the distillation treatment is 135-140 DEG C, such as 135 DEG C, 136 DEG C, 137 DEG C, 138 DEG C, 139 DEG C, or 140 DEG C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0041] In one embodiment of the present application, the temperature of the carbon four and ethanol mixture separated by the stripping treatment is 65-70°C, such as 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0042] In one embodiment of the present application, the temperature of the reaction rectification treatment is 60-70°C, such as 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0043] In one embodiment of the present application, the reaction distillation includes two stages, the stripping treatment and the reaction rectification treatment, i.e. the reaction distillation device includes two independent devices, the stripping column and the reaction rectification column. The pre-product first enters the stripping column to separate the ETBE and the unreacted carbon four and ethanol, and the ETBE is taken out as the product; the unreacted carbon four and ethanol enter the reaction rectification column to continue the reaction and separation, and the ETBE product returns to the stripping column for the stripping treatment, and the carbon four and ethanol separated are subjected to the ethanol recovery treatment.

[0044] In one embodiment of the present application, part of the ethanol taken out by the stripping treatment is returned to the etherification reaction stage for reuse. The taken-out ethanol can also be subjected to heat exchange with the pre-product, and the taken-out ethanol is cooled for reuse while the pre-product is preheated, thereby improving the utilization rate of heat energy.

[0045] In one embodiment of the present application, the temperature of the ethyl tert-butyl ether product taken out by the stripping treatment can be understood as the bottom temperature of the stripping column. The ethyl tert-butyl ether product has a high temperature, and can be cooled by heat exchange, and the cooling method can be selected according to the temperature of the ethyl tert-butyl ether product and the cooling effect, which is not further limited herein. Preferably, the ethyl tert-butyl ether product is subjected to heat exchange with the pre-product, and the ethyl tert-butyl ether product is cooled while the pre-product is preheated, thereby improving the utilization rate of heat energy.

[0046] In one embodiment of the present application, the temperature of the carbon four and ethanol mixture separated by the stripping treatment can be understood as the top temperature of the stripping column.

[0047] In one embodiment of the present application, the operating pressure of the stripping treatment can be adjusted according to the separation effect of the ETBE product, which is not further limited herein. As listed, the pressure of the stripping treatment can be 0.73-0.75 MPa.

[0048] In one embodiment of the present application, the temperature of the reaction rectification treatment is 60-70℃, which can be understood as the overhead temperature of the reaction rectification column being about 60℃, such as 60℃, 62.5℃ and 65℃, etc.; and the bottom temperature being about 70℃, such as 66℃, 68.5℃ and 70℃, etc.

[0049] In one embodiment of the present application, the operating pressure of the reaction rectification treatment can be adjusted according to the reaction and separation effect of ETBE, which is not further limited herein. As an example, the pressure of the reaction rectification treatment can be 0.70-0.73 MPa.

[0050] In one embodiment of the present application, ethanol is supplemented during the reaction rectification treatment to maintain the alcohol / olefin ratio in the reaction rectification treatment to be 1.02-1.05 (molar ratio).

[0051] In one embodiment of the present application, the catalysts used in the first-stage etherification reaction, the second-stage etherification reaction, the third-stage etherification reaction and the reaction rectification are conventional catalysts for preparing ethyl tert-butyl ether by reacting carbon four raw material (isobutylene) with ethanol, and the specific type of the catalyst is not further limited herein.

[0052] In one embodiment of the present application, the ethanol recovery treatment includes countercurrent extraction and ethanol separation performed in sequence.

[0053] In one embodiment of the present application, the extractant used in the countercurrent extraction is water.

[0054] In one embodiment of the present application, the mixture of ethanol and unreacted carbon four serves as the dispersed phase, and water serves as the continuous phase, the two phases are countercurrently contacted, the extract phase (i.e. ethanol aqueous solution containing a small amount of carbon four) is subjected to ethanol separation treatment, and the raffinate phase (i.e. carbon four not containing ethanol) is sent to a downstream unit.

[0055] In one embodiment of the present application, the temperature of the countercurrent extraction can be 40-42℃, and the pressure can be 0.6-0.8 MPa.

[0056] In one embodiment of the present application, the flow rates of the dispersed phase and the continuous phase in the countercurrent extraction can be adjusted according to the extraction of ethanol, which is not further limited herein.

[0057] In one embodiment of the present application, the extract phase is subjected to deacidification treatment after the countercurrent extraction to remove the trace amount of acidic substances carried therein, so as to prevent the acidic substances from gathering to cause corrosion to the equipment and pipelines of the ethanol recovery system. The deacidification treatment can be performed by resin adsorption or alkali neutralization, etc., which can be adjusted according to production needs, which is not further limited herein.

[0058] In one embodiment of the present application, the ethanol separation includes separating ethanol and extractant by distillation, the ethanol is recycled to the etherification reaction, and the extractant is recycled to the countercurrent extraction.

[0059] In one embodiment of the present application, the ethanol obtained by distillation is collected, part of the ethanol is returned to the distillation step as reflux liquid, multiple separations are achieved by providing gas-liquid mass transfer balance to improve the purity of ethanol, and part of the ethanol is recycled to the raw material of the etherification reaction.

[0060] In one embodiment of the present application, the reflux ratio of ethanol during the distillation separation of ethanol can be adjusted according to the separation of ethanol, which is not limited here.

[0061] In one embodiment of the present application, the distilled water is cooled and then recycled to the countercurrent extraction of ethanol.

[0062] In one embodiment of the present application, the temperature of ethanol distillation can be 95-145℃, preferably 96.5-143.5℃; and the pressure can be 0.25-0.3MPa.

[0063] In one embodiment of the present application, the device used in the above preparation method of ethyl tert-butyl ether is as shown in Figure 1 The device includes a reaction unit A, the reaction unit A includes at least two reaction kettles, the pre-product outlet of the reaction unit A is connected with the overhead material inlet of a stripping column B1, the overhead distillate outlet of the stripping column B1 is connected with the bottom material inlet of a reactive distillation column B2, the side line ethanol outlet of the stripping column B1 is connected with the raw material inlet of the reaction unit A, the bottom of the stripping column B1 is provided with a material outlet, and the ETBE product is extracted; the bottom product outlet of the reactive distillation column B2 is connected with the overhead material inlet of the stripping column B1, and the overhead distillate outlet of the reactive distillation column B2 is connected with an ethanol separation unit.

[0064] In order to better illustrate the present application and facilitate understanding of the technical solutions of the present application, the typical but non-limiting embodiments of the present application are as follows:

[0065] Example 1

[0066] The present embodiment provides a preparation method of ethyl tert-butyl ether, which includes:

[0067] The carbon four raw material and ethanol are sequentially subjected to three-stage etherification reaction to obtain a pre-product;

[0068] The temperature of the first-stage etherification reaction is 50°C, and the pressure is 1.35 MPa; the temperature of the second-stage etherification reaction is 60°C, and the pressure is 1.20 MPa; the temperature of the third-stage etherification reaction is 65°C, and the pressure is 1.10 MPa; the alcohol / olefin ratio (molar ratio) is maintained at 1.02-1.05 during the first-stage etherification reaction, the second-stage etherification reaction, and the third-stage etherification reaction, and ethanol is taken out from the side of the rectification column as the raw material for the etherification reaction;

[0069] The pre-product is subjected to rectification treatment, the rectification treatment is performed in a rectification column, the overhead temperature of the rectification column is 68.5°C, the bottom temperature is 138.5°C, the overhead pressure is 0.73 MPaG, and the bottom temperature is 0.75 MPaG, the ETBE product is taken out from the bottom of the rectification column, and the unreacted carbon four and ethanol distilled from the top are subjected to reaction rectification; the reaction rectification is performed in a reaction rectification column, the overhead temperature of the reaction rectification column is 62.5°C, the bottom temperature is 68.5°C, the overhead pressure is 0.70 MPaG, and the bottom temperature is 0.73 MPaG, ethanol is supplemented during the reaction rectification treatment to maintain the alcohol / olefin ratio (molar ratio) in the reaction rectification treatment at 1.02-1.05; the separated ETBE product is returned to the rectification column for rectification treatment, and the separated carbon four and ethanol are subjected to ethanol recovery treatment;

[0070] The mixture of ethanol and unreacted carbon four is used as the dispersed phase, and water is used as the continuous phase, the two phases are countercurrently contacted, the extract phase (i.e., an ethanol aqueous solution containing a small amount of carbon four) is subjected to ethanol separation treatment, and the raffinate phase (i.e., carbon four not containing ethanol) is sent to a downstream unit; the temperature of the countercurrent extraction is 40-42°C, and the pressure is 0.6-0.8 MPa;

[0071] The extract phase is subjected to deacidification treatment and then enters a distillation column for separation of ethanol and water, the ethanol obtained by distillation is collected, part of the ethanol is returned to the distillation step as a reflux liquid, and part of the ethanol is used as the raw material for the etherification reaction; the water obtained by distillation is cooled and then used for countercurrent extraction of ethanol; the ethanol separation is performed in a distillation column, the overhead temperature of the distillation column is 96.5°C, the pressure is 0.25 MPa, the bottom temperature is 143.5°C, and the pressure is 0.3 MPa.

[0072] Example 2

[0073] The present embodiment provides a preparation method of ethyl tert-butyl ether, which comprises:

[0074] The carbon four raw material and ethanol are sequentially subjected to three-stage etherification reactions to obtain a pre-product;

[0075] The temperature of the first-stage etherification reaction is 55°C, and the pressure is 1.40 MPa; the temperature of the second-stage etherification reaction is 65°C, and the pressure is 1.25 MPa; the temperature of the third-stage etherification reaction is 70°C, and the pressure is 1.15 MPa; the alcohol / olefin ratio (molar ratio) is maintained at 1.02-1.05 during the first-stage etherification reaction, the second-stage etherification reaction, and the third-stage etherification reaction, and ethanol is taken out from the side line of the stripping column as the raw material for the etherification reaction;

[0076] The reaction distillation of the pre-product and the ethanol separation treatment are the same as in Example 1.

[0077] Example 3

[0078] The present example provides a method for preparing ethyl tert-butyl ether, which comprises:

[0079] The carbon four raw material and ethanol are sequentially subjected to three-stage etherification reactions to obtain a pre-product;

[0080] The temperature of the first-stage etherification reaction is 40°C, and the pressure is 1.30 MPa; the temperature of the second-stage etherification reaction is 45°C, and the pressure is 1.15 MPa; the temperature of the third-stage etherification reaction is 60°C, and the pressure is 1.00 MPa; the alcohol / olefin ratio (molar ratio) is maintained at 1.02-1.05 during the first-stage etherification reaction, the second-stage etherification reaction, and the third-stage etherification reaction, and ethanol is taken out from the side line of the stripping column as the raw material for the etherification reaction;

[0081] The reaction distillation of the pre-product and the ethanol separation treatment are the same as in Example 1.

[0082] Example 4

[0083] The present example provides a method for preparing ethyl tert-butyl ether, which comprises:

[0084] The carbon four raw material and ethanol are sequentially subjected to three-stage etherification reactions to obtain a pre-product, and the specific method is the same as in Example 1;

[0085] The pre-product is subjected to stripping treatment, which is carried out in a stripping column, the overhead temperature of the stripping column is 65°C, the bottom temperature is 135°C, the overhead pressure is 0.73 MPaG, and the bottom temperature is 0.75 MPaG, the ETBE product is taken out from the bottom, and the unreacted carbon four and ethanol distilled from the top are subjected to reaction rectification; the reaction rectification is carried out in a reaction rectification column, the overhead temperature of the reaction rectification column is 65°C, the bottom temperature is 60°C, the overhead pressure is 0.73 MPaG, and the bottom temperature is 0.75 MPaG, ethanol is supplemented during the reaction rectification treatment to maintain the alcohol / olefin ratio (molar ratio) in the reaction rectification treatment at 1.02-1.05; the separated ETBE product is returned to the stripping column for stripping treatment, and the separated carbon four and ethanol are subjected to ethanol recovery treatment;

[0086] The ethanol separation treatment is the same as that of Example 1.

[0087] Example 5

[0088] The present example provides a method for preparing ethyl tert-butyl ether, which comprises:

[0089] The carbon four raw material and ethanol are sequentially subjected to a tertiary etherification reaction to obtain a pre-product, and the specific method is the same as that of Example 1.

[0090] The pre-product is subjected to a stripping treatment, the stripping treatment is carried out in a stripping column, the overhead temperature of the stripping column is 70°C, the bottom temperature is 140°C, the overhead pressure is 0.73 MPaG, and the bottom temperature is 0.75 MPaG, the ETBE product is collected at the bottom of the column, and the unreacted carbon four and ethanol distilled at the top are subjected to a reactive rectification; the reactive rectification is carried out in a reactive rectification column, the overhead temperature of the reactive rectification column is 70°C, the bottom temperature is 65°C, the overhead pressure is 0.73 MPaG, and the bottom temperature is 0.75 MPaG, ethanol is supplemented during the reactive rectification treatment to maintain the alcohol / olefin ratio (molar ratio) in the reactive rectification treatment at 1.02-1.05; the separated ETBE product is returned to the stripping column for stripping treatment, and the separated carbon four and ethanol are subjected to ethanol recovery treatment.

[0091] The ethanol separation treatment is the same as that of Example 1.

[0092] Comparative Example 1

[0093] In this comparative example, the carbon four raw material and ethanol are only subjected to a primary etherification reaction at 65°C and a pressure of 1.10 MPa, and the other conditions are the same as those of Example 1. The reaction time of this etherification reaction is the same as the total reaction time of the tertiary etherification reaction in Example 1.

[0094] Comparative Example 2

[0095] In this comparative example, the reactive distillation of the pre-product is carried out in a total reactive distillation column, and the other conditions are the same as those of Example 1.

[0096] Comparative Example 3

[0097] In this comparative example, after the pre-product is subjected to a stripping treatment to separate the ETBE product, the unreacted carbon four and ethanol distilled at the top are directly subjected to an ethanol separation treatment, and the other conditions are the same as those of Example 1.

[0098] The composition of the carbon four raw material used in Examples 1-5 and Comparative Examples 1-3 is shown in Table 1, the volume concentration of the ethanol used is 98%, and the catalyst is a D006 catalyst produced by Kerry Environmental Technology Co., Ltd., and the physical property indexes of which are shown in Table 2.

[0099] Table 1

[0100]

[0101] Table 2

[0102]

[0103]

[0104] The ETBE product of Examples 1-5 and Comparative Examples 1-3 was sampled, and the sample was analyzed by liquid chromatography to determine the purity of the ETBE product; the theoretical yield of ETBE was calculated based on the total amount of carbon four raw material used, and the yield of ETBE was calculated based on the purity of the ETBE product and the total ETBE yield, and the results are shown in Table 3.

[0105] Table 3

[0106] ETBE product yield ETBE product purity Example 1 94.58％ 95.346％ Example 2 94.32％ 95.287％ Example 3 94.52％ 95.312％ Example 4 94.64％ 95.428％ Example 5 94.86％ 95.688％ Comparative Example 1 90.23％ 91.212％ Comparative Example 2 90.08％ 90.107％ Comparative Example 3 90.45％ 92.236％

[0107] As can be seen from the test results in Table 3, the ETBE product purity obtained by the method for preparing ethyl tert-butyl ether provided by the present application can reach 95% or more, and the yield can reach 94% or more. Comparative Example 1 only uses a primary etherification reaction, and because the etherification reaction is not complete, the by-products increase, resulting in a decrease in the ETBE product yield and purity compared to Example 1. In Comparative Example 2, the reaction rectification is carried out in one overall reaction distillation column, i.e., the ethyl tert-butyl ether and unreacted carbon four and ethanol in the pre-product are not separated before reaction rectification, resulting in a decrease in the effect of the reaction rectification, which causes a decrease in the ETBE product yield and purity. In Comparative Example 3, after the pre-product is subjected to stripping treatment to separate the ETBE product, the unreacted carbon four and ethanol distilled from the top are directly subjected to ethanol separation treatment, and are not subjected to reaction rectification, not only lacking a key separation step, but also the unreacted carbon four raw material is not fully utilized, which significantly reduces the ETBE product yield and purity.

[0108] The applicant declares that the above examples illustrate the detailed structural features of the present application, but the present application is not limited to the above detailed structural features, i.e., it does not mean that the present application must rely on the above detailed structural features to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the components selected by the present application, addition of auxiliary components, selection of specific modes, etc., all fall within the protection scope and disclosure scope of the present application.

[0109] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details in the above embodiments, and within the technical concept scope of the present application, the technical solutions of the present application can be subjected to various simple modifications, and these simple modifications all belong to the protection scope of the present application.

[0110] It should be further noted that any technically feasible combination of the various technical features described in the above embodiments is possible, provided that there is no contradiction, and the disclosure of the present application shall be deemed to include all such technically feasible combinations.

[0111] Furthermore, any combination of the various embodiments of the present application is possible, provided that there is no contradiction, and the disclosure of the present application shall be deemed to include all such technically feasible combinations.

Claims

1. A method for preparing ethyl tert-butyl ether, characterized in that: The preparation method comprises: The C4 raw material and ethanol undergo at least two-stage etherification reactions to obtain a pre-product; The pre-product is subjected to reactive distillation, and the reactive distillation includes stripping treatment and reactive distillation treatment; the pre-product is subjected to stripping treatment to produce ethyl tert-butyl ether product, and the separated C4 and ethanol mixture is subjected to reactive distillation treatment; the ethyl tert-butyl ether obtained by the reactive distillation treatment is returned to the stripping treatment, and the C4 and ethanol separated by the reactive distillation are subjected to ethanol recovery treatment.

2. The method for preparing ethyl tert-butyl ether according to claim 1, wherein The etherification reaction includes a first-stage etherification reaction, a second-stage etherification reaction and a third-stage etherification reaction which are carried out in sequence.

3. The method for preparing ethyl tert-butyl ether according to claim 2, wherein: The temperature of the first-stage etherification reaction is 40-55°C and the pressure is 1.3-1.4 MPa; and / or, the temperature of the second-stage etherification reaction is 45-65° C. and the pressure is 1.15-1.25 MPa; and / or, the temperature of the third-stage etherification reaction is 60-70° C. and the pressure is 1.0-1.15 MPa; And / or, the temperature of the third-stage etherification reaction is greater than the temperature of the second-stage etherification reaction, which is greater than the temperature of the first-stage etherification reaction.

4. The method for preparing ethyl tert-butyl ether according to claim 2, wherein: The alcohol-olefin ratios of the first-stage etherification reaction, the second-stage etherification reaction and the third-stage etherification reaction are independently 1.02 to 1.05, respectively, in terms of molar ratio.

5. The method for preparing ethyl tert-butyl ether according to claim 1, wherein The temperature of the ethyl tert-butyl ether product produced by the distillation treatment is 135-140° C. And / or, the temperature of the C4 and ethanol mixture separated by the distillation treatment is 65-70°C.

6. The method for preparing ethyl tert-butyl ether according to claim 1, wherein The temperature of the reactive distillation treatment is 60-70°C.

7. The method for preparing ethyl tert-butyl ether according to claim 1, wherein During the reactive distillation process, ethanol is added to maintain the alcohol-to-olefin ratio in the reactive distillation process at a molar ratio of 1.02 to 1.

05.

8. The method for preparing ethyl tert-butyl ether according to claim 1, wherein The ethanol recovery process includes countercurrent extraction and ethanol separation performed in sequence.

9. The method for preparing ethyl tert-butyl ether according to claim 8, wherein The extractant used in the countercurrent extraction is water.

10. The method for preparing ethyl tert-butyl ether according to claim 8, wherein The ethanol separation comprises separating ethanol and an extractant by distillation, wherein the ethanol is recycled for the etherification reaction, and the extractant is recycled for the countercurrent extraction.

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