Start-up method of an etbe plant and method for producing etbe

Abstract

The application discloses a start-up method of an ETBE device and an ETBE production method, and the ETBE device comprises a catalytic rectifying tower newly provided with an ETBE catalyst bed layer, and the start-up method comprises the following steps: introducing methanol into the catalytic rectifying tower to replace water in the ETBE catalyst bed layer; when the water mass content in the discharge material of the catalytic rectifying tower is less than 15%, introducing carbon four material into the catalytic rectifying tower to remove methanol in the catalytic rectifying tower and the ETBE catalyst bed layer thereof. The application has the advantages that a large amount of water-containing ethanol is not generated in the catalyst dehydration process, residual ethanol does not exist in the catalyst, the dehydration raw material is easy to obtain, the dehydration effect is strengthened, the device start-up time is short, and the amount of unqualified products is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ETBE preparation, and in particular to a method for starting up an ETBE device and a method for producing ETBE. Background Art

[0002] The production of ETBE by reacting mixed C4 with ethanol usually uses a sulfonic acid ion exchange resin catalyst. The fresh catalyst usually contains about 50% water. If used directly for ETBE production, the water in the catalyst will react with the isobutylene in the mixed C4 to form tert-butanol, resulting in a significant reduction in the purity of the ETBE product. Therefore, the water in the catalyst must be removed before use in the etherification reaction.

[0003] CN103127961 discloses a catalyst swelling and soaking process for an MTBE industrial reactor. The process includes introducing, soaking, and dehydrating the reactor. A centrifugal pump is used to introduce the etherified mixed C4 into a reactor containing a new catalyst. The reactor is at room temperature, the reactor pressure is increased, the reactor inlet and outlet are closed, and the mixed C4 is allowed to stand for a while. The mixed C4 is then withdrawn to a standing tank using its own pressure. The material in the standing tank is then allowed to stand for dehydration and shipped. The mixed C4 has a relatively weak polarity, and high reactor pressure is required to displace moisture from the catalyst. This cannot remove moisture deep within the catalyst pores, resulting in poor dehydration. Initially, a certain amount of substandard product with excessive tert-butyl alcohol content will still be produced. This process relies on soaking the catalyst for extended periods of time and multiple times, which takes a long time and consumes a large amount of C4 material. Summary of the Invention

[0004] The present invention provides a method for starting up an ETBE device and a method for producing ETBE, which have the advantages of not generating a large amount of hydrous ethanol during the catalyst dehydration process, not having residual ethanol in the catalyst, easily available dehydration raw materials, enhanced dehydration effect, short device start-up time, and greatly reduced amount of unqualified products.

[0005] The inventors of this invention, in Chinese Patent No. 202211049176, disclose a process and apparatus for treating ETBE catalysts. ETBE is used to remove moisture from the catalyst. The ETBE and water are then discharged into the reflux tank of a catalytic distillation column, where they settle and separate into separate layers. The water in the lower layer is then removed, and the ETBE in the upper layer is recycled. For new ETBE plants, obtaining the dehydrated raw material ETBE before the plant is operational is difficult.

[0006] The inventors of the present invention have discovered through research that ETBE catalysts typically utilize ethanol displacement dehydration, which produces a large amount of ethanol-water solution. The ethanol in the solution is recovered by distillation. Since ethanol and water form an azeotrope, the ethanol recovered by distillation contains about 5% water by mass. Therefore, the catalyst dehydration process produces a large amount of hydrous ethanol, which cannot be used for ETBE production and is difficult to handle because the water in the ethanol reacts with the isobutylene in the mixed C4 to form tert-butanol, resulting in the tert-butanol content of the ETBE product exceeding the standard. At the same time, after the ethanol displacement dehydration, a large amount of residual ethanol is contained in the device and the catalyst. For a long period of time at the beginning of the operation, a large amount of excess ethanol from the reaction enters the catalytic distillation tower. Since the azeotropic composition of ethanol in the azeotrope formed by C4 and ethanol is particularly low, the ethanol exceeds the maximum concentration composition of the azeotrope and cannot be azeotropically distilled from the top of the tower. Instead, it enters the bottom of the tower, causing the ethanol content in the ETBE product at the bottom of the tower to significantly exceed the standard. As a result, a large amount of substandard products with excessive ethanol in the early stage of operation and a long start-up time are required.

[0007] In order to solve the above problems, the present invention provides, on one hand, a method for starting up an ETBE device, wherein the ETBE device includes a reaction unit newly equipped with an ETBE catalyst bed, and the method comprises:

[0008] Methanol is introduced into the reaction unit to displace the water in the ETBE catalyst bed. When the water mass content in the discharge material of the reaction unit is less than 15%, a C4 material is introduced into the reaction unit to remove the methanol in the reaction unit and its ETBE catalyst bed, and the isobutylene mass content in the C4 material is less than 1.0%.

[0009] In the present invention, the reaction unit of the ETBE device includes the following three configurations:

[0010] Form 1: The reaction unit of the ETBE device includes at least one reactor but does not include a catalytic distillation column;

[0011] Form 2: The reaction unit of the ETBE device includes at least one catalytic distillation column but does not include a reactor;

[0012] Form 3: The reaction unit of the ETBE device includes a reactor and a catalytic distillation tower, wherein the reactor and the catalytic distillation tower are connected in series.

[0013] In some embodiments of the present invention, the reaction unit of the ETBE device includes a reactor, wherein the reactor is newly equipped with an ETBE catalyst bed, and the startup method includes:

[0014] a) introducing methanol into the reactor to displace the water in the ETBE catalyst bed in the reactor, wherein when the water content in the discharge material from the reactor is less than 15% by weight, performing step b);

[0015] b) introducing a C4 material into the reactor to remove methanol from the reactor and its ETBE catalyst bed.

[0016] In other embodiments of the present invention, the reaction unit of the ETBE device includes a catalytic distillation tower, in which a new ETBE catalyst bed is installed. The startup method includes:

[0017] a) introducing methanol into the catalytic distillation tower to displace water in the ETBE catalyst bed in the catalytic distillation tower, wherein step b) is performed when the water content of the discharge material from the catalytic distillation tower is less than 15% by weight;

[0018] b) introducing a C4 material into the catalytic distillation tower to remove methanol from the catalytic distillation tower and its ETBE catalyst bed.

[0019] In other embodiments of the present invention, the reaction unit of the ETBE device includes a reactor and a catalytic distillation tower connected in series along the material flow direction, wherein each of the reactor and the catalytic distillation tower is newly equipped with an ETBE catalyst bed. The start-up method includes:

[0020] a) introducing methanol into the reactor, or introducing methanol into the reactor and the catalytic distillation column respectively, to displace the water in the ETBE catalyst bed of the reactor and the catalytic distillation column,

[0021] Wherein, when the water mass content in the discharge materials of the reactor and the catalytic distillation tower is less than 15% respectively, step b) is carried out;

[0022] b) introducing a C4 material into the reactor, or introducing a C4 material into the reactor and the catalytic distillation column respectively, to remove methanol from the reactor and the catalytic distillation column and their ETBE catalyst bed.

[0023] Preferably, when the reaction unit includes a reactor, step b) removes methanol from the ETBE catalyst in the reactor by pressure, and preferably the removal conditions of step b) include: the reactor pressure is controlled at 0.4-1.0 MPaG, more preferably 0.6-0.8 MPaG, and the reactor temperature is room temperature.

[0024] Preferably, when the reaction unit includes a catalytic distillation tower, step b) removes methanol from the ETBE catalyst in the catalytic distillation tower by distillation. More preferably, the removal conditions of step b) also include: distilling the material in the catalytic distillation tower. Further preferred distillation conditions include: controlling the temperature of the ETBE catalyst bed to 40-80°C, further preferably 40-70°C; controlling the top pressure of the catalytic distillation tower to 0.3-1.0 MPaG, further preferably 0.4-0.5 MPaG; and controlling the reflux ratio to 0.5-15, further preferably 0.5-7.

[0025] Preferably, the removal conditions in step b) further include: the volume space velocity of the C4 material passing through the ETBE catalyst is 0.2-10h -1 , more preferably 1-5h -1 .

[0026] Preferably, the replacement conditions of step a) include: normal temperature and pressure, and a volume space velocity of methanol passing through the ETBE catalyst of 0.5-10h -1 , more preferably 1-5h -1 .

[0027] Preferably, step b) is performed when the water content in the discharge material from the reactor and / or the catalytic distillation column is less than 10% by mass.

[0028] Preferably, the mass content of isobutylene in the C4 material is less than 0.5%, more preferably less than 0.1%.

[0029] Preferably, the C4 material comes from at least one of the C4 in the oil refining process, the C4 in the ethylene cracking process, the C4 in the methanol to olefins process, the C4 remaining after the etherification reaction to produce MTBE and ETBE, or the light C4 produced by the 1-butene separation device.

[0030] Preferably, the water content in the fresh ETBE catalyst is 10%-80% by mass.

[0031] Preferably, the ETBE catalyst is an ion exchange resin catalyst, more preferably a sulfonic acid type cation exchange resin catalyst.

[0032] Preferably, the number of reactors in the ETBE device is two or more, connected in series or in parallel.

[0033] Preferably, the ETBE device further comprises: an extraction tower and a distillation recovery tower;

[0034] The distillation recovery tower is connected to the reactor and / or the catalytic distillation tower, and is used to separate water and methanol from the reactor and / or the catalytic distillation tower;

[0035] The extraction tower is connected to the top of the catalytic distillation tower and is used for extracting and separating the material discharged from the top of the catalytic distillation tower.

[0036] Preferably, the extractant in the extraction column comprises water;

[0037] More preferably, the distillation recovery tower is connected to the extraction tower, so as to return the water separated by the distillation recovery tower to the extraction tower as an extractant.

[0038] The invention discloses a method for producing ETBE. After an ETBE device is started up by adopting the start-up method of the invention, ethanol and a C4 raw material are introduced into a reactor or a catalytic distillation tower to produce ETBE.

[0039] Preferably, when the methanol mass content in the discharge material of the reactor and / or the catalytic distillation tower is less than 10%, more preferably less than 3%, ethanol and C4 raw materials are fed into the reactor or the catalytic distillation tower to produce ETBE.

[0040] Preferably, the ETBE device further comprises an extraction tower and a distillation recovery tower; wherein the distillation recovery tower is connected to the extraction tower and is used to separate water and ethanol from the extraction tower;

[0041] The extraction tower is connected to the top of the catalytic distillation tower and is used to extract and separate the top discharge of the catalytic distillation tower;

[0042] It is more preferred that all materials in the extraction tower and the distillation recovery tower be unloaded before ethanol and C4 raw materials are introduced into the reactor or catalytic distillation tower to produce ETBE, and it is further preferred that all materials in the extraction tower and the distillation recovery tower be unloaded before ethanol and C4 raw materials are introduced into the reactor and the catalytic distillation tower respectively to produce ETBE.

[0043] Through the above technical scheme, the present invention first uses methanol to remove moisture from a fresh ETBE catalyst in a device, and then uses C4 material to remove methanol in the device and in the catalyst. Compared with conventional use of ethanol to remove moisture from the catalyst, a large amount of hydrous ethanol is not produced; no residual ethanol is present in the catalyst at the initial stage of operation, and no unqualified products due to excessive residual ethanol are produced; moisture in the catalyst is further removed during the process of removing methanol from the C4, thereby enhancing the dehydration effect, and no unqualified products due to excessive tert-butyl alcohol are produced at the initial stage of operation; C4 is easily obtained after dehydrating the raw materials methanol and ether; the C4 residual in the catalyst will not affect the purity of the product; the start-up time of the device is short, and the amount of unqualified products is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flow chart of a method for starting up an ETBE device according to some embodiments of the present invention;

[0045] Figure 2is a flow chart of a method for starting up an ETBE device according to other embodiments of the present invention;

[0046] Figure 3 is a flow chart of a method for starting up an ETBE device according to other embodiments of the present invention;

[0047] Figure 4 is a flow chart of a method for starting up an ETBE device according to other embodiments of the present invention;

[0048] Figure 5 It is a flow chart of the start-up method of the ETBE device according to other embodiments of the present invention.

[0049] Description of Reference Numerals

[0050] 1 reactor; 2 catalytic distillation tower; 3 extraction tower; 4 distillation recovery tower; 5 distillation tower. DETAILED DESCRIPTION

[0051] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0052] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" generally refer to up, down, left, right as shown in the reference drawings; "inside, outside" refer to inside and outside relative to the outline of each component itself.

[0053] The present invention discloses a method for starting up an ETBE device, such as Figure 1 As shown, the ETBE device includes a reaction unit newly equipped with an ETBE catalyst bed, and the start-up method includes:

[0054] Methanol is introduced into the reaction unit to displace the water in the ETBE catalyst bed. When the water mass content in the discharge material of the reaction unit is less than 15%, C4 material is introduced into the reaction unit to remove the methanol in the reaction unit and its ETBE catalyst bed.

[0055] In some embodiments of the present invention, Figure 1 As shown, the reaction unit of the ETBE device includes a reactor 1 and a catalytic distillation tower 2 connected in series along the material flow direction. The reactor 1 and the catalytic distillation tower 2 are each newly equipped with an ETBE catalyst bed. The startup method includes dehydrating the fresh ETBE catalyst in the reactor and the catalytic distillation tower, specifically including:

[0056] a) feeding methanol into reactor 1, preferably feeding methanol into both reactor 1 and catalytic distillation tower 2, to displace water in the ETBE catalyst bed in the reactor; the reactor is connected to the catalytic distillation tower; the material containing methanol in the reactor can be directly discharged or passed into the catalytic distillation tower to further displace water in the ETBE catalyst bed in the catalytic distillation tower; wherein, when the water mass content of the discharge materials from reactor 1 and catalytic distillation tower 2 is less than 15%, step b) is performed;

[0057] b) introducing a C4 material into the reactor 1, preferably introducing a C4 material into the reactor 1 and the catalytic distillation column 2, respectively, to remove methanol from the reactor and the catalytic distillation column and their ETBE catalyst bed.

[0058] In some embodiments of the present invention, methanol is removed from the ETBE catalyst in the reactor by pressure, and preferably the removal conditions of step b) include: the pressure of reactor 1 is controlled at 0.4-1.0 MPaG, more preferably 0.6-0.8 MPaG.

[0059] In some embodiments of the present invention, methanol is removed from the ETBE catalyst in the catalytic distillation tower 2 by distillation. Preferably, the removal conditions of step b) also include: distilling the material in the catalytic distillation tower 2 so that the methanol inside the catalyst leaves the catalyst with carbon four by azeotropic effect under heating conditions, and the top discharge is an azeotropic mixture of carbon four and methanol, and the bottom discharge is methanol and a small amount of water. Preferably, the distillation conditions include: controlling the temperature of the ETBE catalyst bed to 40-80°C, preferably 40-70°C; controlling the top pressure of the catalytic distillation tower 2 to 0.3-1.0MpaG, preferably 0.4-0.5MpaG; controlling the reflux ratio to 0.2-15, preferably 0.5-7.

[0060] In some embodiments of the present invention, the removal conditions in step b) further include: the volume space velocity of the C4 material passing through the ETBE catalyst is 0.5-10h -1 , preferably 1-5h -1 .

[0061] In some embodiments of the present invention, the replacement conditions of step a) include: normal temperature and pressure, the volume space velocity of methanol passing through the ETBE catalyst is 0.5-10h -1 , preferably 1-5h -1 .

[0062] In order to reduce the amount of methanol used, in some embodiments of the present invention, the methanol-containing material at the bottom of the reactor 1 is circulated back to the ETBE catalyst bed of the reactor 1 multiple times by a pump, and / or the methanol-containing material in the bottom of the catalytic distillation tower 2 is circulated back to the ETBE catalyst bed of the catalytic distillation tower 2 multiple times by a pump. In the present invention, as long as the methanol-containing material can be returned to the top of the ETBE catalyst bed in the catalytic distillation tower, there are no other special requirements. For example, it can enter the tower through the reflux feed port of the catalytic distillation tower, or through the ethanol feed port of the catalytic distillation tower. It can enter the tower through one catalytic distillation tower ethanol feed port or through two or more catalytic distillation tower ethanol feed ports respectively. The present invention will not be repeated here.

[0063] In some embodiments of the present invention, when the water content in the discharge material from the reactor 1 or the catalytic distillation tower 2 is less than 10% by mass, step b) is performed to achieve a better dehydration effect.

[0064] In the present invention, the mass content of isobutylene in the C4 material used for removing methanol is less than 1.0%, preferably less than 0.5%, more preferably less than 0.4%, and further preferably less than 0.1%.

[0065] In some embodiments of the present invention, the C4 material comes from at least one of the C4 in the oil refining process, the C4 in the ethylene cracking process, the C4 in the methanol to olefins process, or the C4 remaining after the etherification reaction to produce MTBE and ETBE (referred to as post-etherification C4, the mass content of isobutylene in post-etherification C4 is usually less than 0.4% or even less than 0.1%), or the light C4 produced by the 1-butene separation device.

[0066] In some embodiments of the present invention, the water content in the fresh ETBE catalyst is 10%-80% by mass.

[0067] In some embodiments of the present invention, the loading form of the ETBE catalyst in the catalytic distillation tower is selected from bulk, bundled or modular; commonly used ETBE catalysts can be used in the present invention. In some embodiments of the present invention, the ETBE catalyst is an ion exchange resin catalyst, preferably a sulfonic acid type cation exchange resin catalyst.

[0068] In some embodiments of the present invention, the reactor 1 is selected from a mixed bed reactor, an adiabatic fixed bed reactor, a shell-and-tube fixed bed reactor, or an expanded bed reactor.

[0069] In order to recycle methanol and water, in some embodiments of the present invention, as Figure 2As shown, the ETBE device also includes a distillation recovery tower 4; wherein the distillation recovery tower 4 is connected to the reactor 1 and / or the catalytic distillation tower 2, and is used to separate water and methanol from the reactor 1 and / or the catalytic distillation tower 2; specifically, in step a), the reactor is at room temperature and pressure, methanol enters the reactor, and the water inside the reactor catalyst is displaced, and the reactor outlet material is methanol and water. The reactor outlet material can be passed into the catalytic distillation tower 2 or directly enter the distillation recovery tower 4 to be separated into methanol and water; similarly, the discharge from the bottom of the catalytic distillation tower 2 can also be separated into methanol and water through the distillation recovery tower 4.

[0070] In order to recover C4 material and methanol, in some embodiments of the present invention, as Figure 3 As shown, the ETBE device includes an extraction tower 3 and a distillation recovery tower 4; the extraction tower 3 is connected to the top of the catalytic distillation tower 2, and is used to extract and separate the azeotropic mixture of C4 and methanol; in some embodiments of the present invention, the extractant in the extraction tower 3 preferably includes water.

[0071] In some embodiments of the present invention, Figure 3 As shown, it is more preferred that the distillation recovery tower 4 is connected to the extraction tower 3 to return the water in the distillation recovery tower 4 to the extraction tower 3 as an extractant.

[0072] The start-up method of the present invention is also applicable to the start-up production of an MTBE device converted into an ETBE device.

[0073] The invention discloses a method for producing ETBE. After an ETBE device is started up by adopting the start-up method of the invention, ethanol and C4 raw materials are introduced into a reaction unit to produce ETBE.

[0074] In some embodiments of the ETBE production method of the present invention, when the methanol content in the mixture containing C4 and methanol discharged from reactor 1 and / or catalytic distillation tower 2 after C4 demethanolation is less than 10% by weight, preferably less than 3%, ethanol and C4 raw materials are fed into reactor 1 or catalytic distillation tower 2 to produce ETBE, preferably, ethanol and C4 raw materials are fed into reactor 1 to produce ETBE. Due to trace amounts of methanol remaining in the ETBE catalyst, the discharge product of reactor 1 and / or catalytic distillation tower 2 contains a small amount of MTBE in addition to ETBE at the initial start-up. As the start-up time increases, the MTBE content gradually decreases until it disappears.

[0075] In the present invention, Figure 3As shown, the ETBE device includes a reactor 1, a catalytic distillation tower 2, an extraction tower 3 and a distillation recovery tower 4. The reactor 1 and the catalytic distillation tower 2 are connected in series, and the distillation recovery tower 4 is connected to the extraction tower 3 for separating water and ethanol from the extraction tower 3; the extraction tower 3 is connected to the top of the catalytic distillation tower 2 for extracting and separating the top discharge of the catalytic distillation tower 2 (azeotropic mixture of ethanol and C4).

[0076] In some embodiments of the ETBE production method of the present invention, before ethanol and C4 raw materials are introduced into the reactor 1 to produce ETBE, all the materials in the extraction tower 3 and the distillation recovery tower 4 are unloaded. Specifically, in step b), when the top and bottom discharges of the catalytic distillation tower are separated into C4, methanol and water by the extraction tower 3 and the distillation recovery tower 4, after the separation is completed, all the materials in the extraction tower 3 and the distillation recovery tower 4 are unloaded, and then ethanol and C4 raw materials are introduced to produce ETBE. During the production of ETBE, C4, ethanol and water can be extracted and separated by the extraction tower 3 and the distillation recovery tower 4. The operation of unloading all the materials in the extraction tower 3 and the distillation recovery tower 4 can remove the methanol in the ETBE device more cleanly, further shortening the subsequent start-up time.

[0077] The present invention is further described below through embodiments, but the present invention is not limited thereto.

[0078] Example 1

[0079] use Figure 3 The process flow shown in the figure sequentially follows the following steps: a) Methanol is used to remove moisture from the ETBE catalyst loaded in reactor 1 and catalytic distillation column 2. The ETBE catalyst is a sulfonic acid cation exchange resin catalyst with a water content of 50% by weight. Methanol enters reactor 1, and the material at the reactor outlet enters catalytic distillation column 2. A catalytic distillation column reflux pump is used to transfer the methanol-containing material in the bottom of the column to the upper reaction section. Both reactor 1 and catalytic distillation column 2 are at room temperature and pressure, and the volumetric space velocity of methanol passing through the catalyst in the reactor is 2h / min. -1 The catalyst volume space velocity of the catalytic distillation tower is 1h -1 ; Through the reflux feed port of the catalytic distillation tower into the tower, the bottom of the tower into the distillation recovery tower 4 separated into methanol and water; when the catalytic distillation tower discharge material water content of 10% by mass, step b);

[0080] b) Using etherified C4 to remove methanol from reactor 1, catalytic distillation tower 2, and its catalyst. The etherified C4 is derived from C4 remaining after etherification of C4 from the oil refining process to produce MTBE. The isobutylene content in the etherified C4 is 0.05% by weight. The etherified C4 enters reactor 1, which is maintained at a pressure of 0.7 MPaG and room temperature. The material exiting reactor 1 enters catalytic distillation tower 2, which is heated by a bottom heat source to maintain the catalyst bed temperature in the reaction section of the catalytic distillation tower at 40-60°C. The top pressure of the catalytic distillation tower is controlled at 0.5 MPaG, and the reflux ratio is controlled at 1.0. The bottom discharge is methanol and a small amount of water. The top of the tower is discharged into the extraction tower, and water is used as the extractant to extract the methanol. The ether discharged from the top of the extraction tower is recovered by the C4 discharge device. The methanol and water discharged from the bottom of the extraction tower are separated into methanol and water by the distillation recovery tower. The water is discharged from the bottom of the distillation recovery tower and returned to the extraction tower for recycling. The excess water is discharged from the device, and the methanol is discharged from the top of the distillation recovery tower. The volume space velocity of C4 passing through the catalyst in the reactor is 3h -1 The catalyst volume space velocity of the catalytic distillation tower is 2h -1 When the methanol content in the reactor discharge is 1.8% by mass and the methanol content in the catalytic distillation tower top discharge is 2.9% by mass, the reactor stops feeding ether and C4, and proceeds to step c);

[0081] c) ethanol and a C4 feedstock containing 22% by mass of isobutylene are introduced into reactor 1, and the outlet material of reactor 1 enters catalytic distillation tower 2, and the production of ETBE is started; wherein, the reactor inlet temperature is controlled at 45° C., the pressure at the top of the catalytic distillation tower is controlled at 0.5 MPaG, the reflux ratio is controlled at 1.0, the temperature at the top of the catalytic distillation tower is 55° C., and the temperature at the bottom of the tower is 142° C. The bottom discharge of the catalytic distillation tower is the product ETBE, and the top material enters extraction tower 3, where water is used as an extractant to extract the ethanol therein. The ethanol and water at the bottom discharge of the extraction tower are then separated into ethanol and water through a distillation recovery tower 4, and the water is discharged from the bottom of the distillation recovery tower 4 and returned to the extraction tower 3 for recycling, and the ethanol is discharged from the top of the distillation recovery tower 4 to a discharge device;

[0082] The ETBE catalytic dehydration process did not produce difficult-to-handle aqueous ethanol. The compositions of the ETBE products after 83 and 93 hours of operation are shown in Table 1.

[0083] Example 2

[0084] The same conditions as in Example 1 were used, except that: in step b) after the ether feed to the reactor 1 was stopped and the C4 was removed, all the materials in the extraction tower 3 and the distillation recovery tower 4 were discharged, and then step c) was performed;

[0085] The ETBE catalyst dehydration process does not produce difficult-to-handle aqueous ethanol. The composition of the ETBE product after 83 hours of operation is shown in Table 1.

[0086] Example 3

[0087] The same conditions as in Example 2 were used, except that: a) when the water content in the materials discharged from the reactor 1 and the catalytic distillation tower 2 was 8%, step b) was performed, the isobutylene content in the C4 after etherification in step b) was 0.2%, the pressure in the reactor 1 was 0.6 MPaG, the catalyst bed temperature in the reaction section of the catalytic distillation tower 2 was maintained at 50-65°C, the pressure at the top of the catalytic distillation tower was controlled at 0.6 MPaG, the reflux ratio was controlled at 0.8, and the volumetric space velocity of the C4 through the catalyst in the reactor was 5h -1 The volumetric space velocity of the catalytic distillation tower is 4h -1 When the methanol content in the reactor discharge is 1.6% by mass and the methanol content in the catalytic distillation tower top discharge is 2.5% by mass, the ether feed to reactor 1 is stopped;

[0088] The ETBE catalyst dehydration process does not produce difficult-to-handle aqueous ethanol. The composition of the ETBE product after 83 hours of operation is shown in Table 1.

[0089] Example 4

[0090] use Figure 4 The process flow shown in the figure sequentially performs the following steps: a) Methanol is used to remove moisture from the ETBE catalyst loaded in catalytic distillation tower 2. The ETBE catalyst is a sulfonic acid type cation exchange resin catalyst, and the water content in the catalyst is 45%. Methanol enters catalytic distillation tower 2, and a catalytic distillation tower reflux pump is used to feed the methanol-containing material in the bottom of the tower to the upper part of the reaction section, and then enters the tower through the catalytic distillation tower reflux feed port. The catalytic distillation tower is at normal temperature and pressure, and the volumetric space velocity of methanol passing through the catalyst in the reaction section is 3h. -1 The bottom discharge enters the distillation recovery tower 4 and is separated into methanol and water, and the methanol and water are discharged from the recovery device respectively; when the water content of the material discharged from the catalytic distillation tower 2 is 14% by mass, step b);

[0091] b) Methanol within catalytic distillation tower 2 and the catalyst is removed using post-etherification C4. Post-etherification C4 is the C4 remaining after the C4 from the ethylene cracking process undergoes etherification to produce MTBE. The isobutylene content in post-etherification C4 is 0.12% by weight. The post-etherification C4 enters catalytic distillation tower 2, which is heated by a bottom heat source to maintain the catalyst bed temperature in the reaction section of catalytic distillation tower 2 at 55-60°C. The top pressure of catalytic distillation tower 2 is controlled at 0.6 MPaG, and the reflux ratio is controlled at 1.6. The bottom discharge consists of methanol and a small amount of water, which enters distillation recovery tower 4 for separation into methanol and water. The top discharge of catalytic distillation tower 2 enters extraction tower 3, where water is used as an extractant to extract the methanol. The post-etherification C4 discharge from the extraction tower is recovered by a discharge device. The methanol-water discharge from the bottom of the extraction tower also enters distillation recovery tower 4 for separation into methanol and water. Water is discharged from the bottom of the distillation recovery tower and returned to extraction tower 3 for recycling. Excess water is discharged by a discharge device, and methanol is recovered by the top discharge device of distillation recovery tower 4. The volumetric space velocity of the etherified C4 through the catalytic distillation tower 2 is 1h -1 When the methanol content in the top discharge of the catalytic distillation tower 2 is 3.8%, the ether addition and C4 addition are stopped, and step c) is performed;

[0092] c) introducing ethanol and a C4 feedstock containing 6% by mass of isobutylene into a catalytic distillation tower 2 to start production of ETBE; controlling the top pressure of the catalytic distillation tower 2 at 0.6 MPaG and the reflux ratio at 1.3, the top temperature of the catalytic distillation tower being 59° C. and the bottom temperature being 147° C., the bottom discharge of the catalytic distillation tower is the product ETBE, and the top material enters an extraction tower 3 where ethanol is extracted with water as an extractant. The ethanol and water discharged from the bottom discharge of the extraction tower are then separated into ethanol and water by a distillation recovery tower 4, the water is discharged from the bottom of the distillation recovery tower 4 and returned to the extraction tower 3 for recycling, and the ethanol is discharged from the top discharge device of the distillation recovery tower;

[0093] The ETBE catalyst dehydration process does not produce difficult-to-handle aqueous ethanol. The composition of the ETBE product after 93 hours of operation is shown in Table 1.

[0094] Example 5

[0095] use Figure 5 The process flow shown in the figure is as follows: a) methanol is used to remove water from the ETBE catalyst loaded in reactor 1. The ETBE catalyst is a sulfonic acid type cation exchange resin catalyst, and the water content in the catalyst is 55%. Methanol enters reactor 1, which is at room temperature and pressure. The volumetric space velocity of methanol passing through the catalyst in reactor 1 is 4h -1 The discharge from the reactor 1 enters the distillation recovery tower 4 and is separated into methanol and water, and the methanol and water are discharged from the recovery device respectively; when the water content of the material discharged from the reactor 1 is 5% by mass, step b) is performed;

[0096] b) C4 is used to remove methanol from reactor 1 and the catalyst. The C4 is derived from the light C4 produced by the 1-butene separation unit, and the isobutylene content of the light C4 is 0.01% by weight. The light C4 enters reactor 1, where the pressure is 0.9 MPaG and the temperature is room temperature. The material at the outlet of reactor 1 enters distillation tower 5, which is heated by a heat source in the bottom of the tower. The pressure at the top of distillation tower 5 is controlled at 0.55 MPaG, and the reflux ratio is controlled at 3. The bottom discharge consists of methanol and a small amount of water, which enters distillation recovery tower 4 for separation into methanol and water. The top discharge of distillation tower 5 enters extraction tower 3, where water is used as an extractant to extract the methanol. The light C4 discharge from the top of the extraction tower is recovered by the discharge device. The methanol-water solution discharged from the bottom of the extraction tower also enters distillation recovery tower 4 for separation into methanol and water. Water is discharged from the bottom of the distillation recovery tower and returned to the extraction tower 3 for recycling. Excess water is discharged by the discharge device, and methanol is recovered by the discharge device at the top of the distillation recovery tower 4. The volumetric space velocity of the light C4 through the catalyst of reactor 1 is 6 h / min. -1 When the methanol content in the discharge of reactor 1 is 2.4%, the addition of light C4 is stopped and step c) is performed;

[0097] c) introducing ethanol and isobutylene with a mass content of 12% C4 into the reactor 1 to start production of ETBE; the reactor 1 inlet temperature is 40° C., the reactor 1 outlet material enters the distillation tower 5, the distillation tower 5 top pressure is controlled at 0.55 MPaG, the reflux ratio is controlled at 0.8, the distillation tower top temperature is 56° C., the tower bottom temperature is 143° C., the distillation tower bottom discharge is the product ETBE, the tower top material enters the extraction tower 3, water is used as the extraction agent to extract the ethanol therein, the extraction tower bottom discharge ethanol and water are then separated into ethanol and water through the distillation recovery tower 4, the water is discharged from the distillation recovery tower 4 bottom, returned to the extraction tower 3 for recycling, and ethanol is discharged from the distillation recovery tower top discharge device;

[0098] The ETBE catalyst dehydration process does not produce difficult-to-handle aqueous ethanol. The composition of the ETBE product after 93 hours of operation is shown in Table 1.

[0099] Comparative Example 1

[0100] The same conditions as in Example 1 were used, except that the methanol in step a) was replaced with ethanol; and step b) was omitted.

[0101] The ETBE catalyst dehydration process produced a large amount of hydrous ethanol, which was difficult to handle. The composition of the ETBE product 93 hours and 146 hours after start-up is shown in Table 1.

[0102] Table 1: Product ETBE composition and indicators

[0103]

[0104]

[0105] The results of Example 1 and Comparative Example 1 in Table 1 show that, compared with the conventional use of ethanol to remove moisture from the catalyst, in addition to not producing a large amount of hydrous ethanol during the startup process; there is no residual ethanol in the catalyst after startup, and no unqualified products due to excessive residual ethanol; there are no unqualified products due to excessive tert-butanol; after the start-up of the device, the time it takes for the ETBE product to reach the qualified index is short, and the amount of unqualified products is greatly reduced.

[0106] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for starting up an ETBE device, characterized in that: The ETBE unit includes a reaction unit newly equipped with an ETBE catalyst bed. The startup method includes: Methanol is introduced into the reaction unit to displace water in the ETBE catalyst bed. When the water content in the discharge material of the reaction unit is less than 15% by weight, a C4 material is introduced into the reaction unit to remove methanol from the reaction unit and the ETBE catalyst bed, and the isobutylene content in the C4 material is less than 1.0% by weight. When the methanol content in the discharge material of the reaction unit is less than 10% by mass, the feeding of C4 material is stopped.

2. The start-up method according to claim 1, wherein: The reaction unit of the ETBE device comprises a reactor (1), wherein the reactor (1) is newly equipped with an ETBE catalyst bed. The start-up method comprises: a) introducing methanol into the reactor (1) to displace the water in the ETBE catalyst bed in the reactor (1), wherein when the water content in the discharge material of the reactor (1) is less than 15% by weight, step b) is performed; b) introducing C4 material into the reactor (1) to remove methanol in the reactor (1) and its ETBE catalyst bed.

3. The method for starting a work according to claim 1, wherein: The reaction unit of the ETBE device comprises a catalytic distillation tower (2), wherein a ETBE catalyst bed is newly installed in the catalytic distillation tower (2). The start-up method comprises: a) introducing methanol into the catalytic distillation tower (2) to displace the water in the ETBE catalyst bed in the catalytic distillation tower (2), wherein when the water content of the discharge material from the catalytic distillation tower (2) is less than 15% by mass, step b) is performed; b) introducing C4 material into the catalytic distillation tower (2) to remove methanol from the catalytic distillation tower (2) and its ETBE catalyst bed.

4. The method for starting a work according to claim 1, wherein: The reaction unit of the ETBE device comprises a reactor (1) and a catalytic distillation tower (2) connected in series along the material flow direction, wherein each of the reactor (1) and the catalytic distillation tower (2) is newly equipped with an ETBE catalyst bed. The start-up method comprises: a) introducing methanol into the reactor (1), or introducing methanol into the reactor (1) and the catalytic distillation tower (2) respectively, to displace the water in the ETBE catalyst bed of the reactor (1) and the catalytic distillation tower (2), wherein step b) is performed when the water content by mass of the discharge materials of the reactor (1) and the catalytic distillation tower (2) is less than 15% respectively; b) introducing a C4 material into the reactor (1), or introducing a C4 material into the reactor (1) and the catalytic distillation tower (2), respectively, to remove methanol from the reactor (1), the catalytic distillation tower (2) and the ETBE catalyst bed.

5. The method for starting work according to any one of claims 2 to 4, wherein: When the reaction unit includes a reactor, the removal conditions of step b) include: the pressure of the reactor (1) is controlled at 0.4-1.0 MPaG, the temperature of the reactor is room temperature; and / or When the reaction unit includes a catalytic distillation tower, the removal conditions of step b) further include: distilling the material in the catalytic distillation tower (2); and / or The removal conditions in step b) also include: the volume space velocity of the C4 material passing through the ETBE catalyst is 0.5-10h -1 .

6. The method for starting work according to claim 5, wherein: The removal conditions of step b) include: the pressure of the reactor (1) is controlled at 0.6-0.8 MPaG; and / or The distillation conditions include: controlling the temperature of the ETBE catalyst bed to 40-80°C, controlling the top pressure of the catalytic distillation tower (2) to 0.3-1.0 MPaG, and controlling the reflux ratio to 0.2-15; and / or The volume space velocity of C4 material passing through ETBE catalyst is 1-5h -1 .

7. The method for starting a work according to claim 6, wherein: The distillation conditions include: controlling the temperature of the ETBE catalyst bed to 40-70°C, controlling the top pressure of the catalytic distillation tower (2) to 0.4-0.5 MPaG, and controlling the reflux ratio to 0.5-7.

8. The method for starting a work according to any one of claims 2 to 4, wherein: The replacement conditions of step a) include: normal temperature and pressure, and a volume space velocity of methanol passing through the ETBE catalyst of 0.5-10h -1 ; and / or When the water content in the discharge material from the reactor (1) and / or the catalytic distillation tower (2) is less than 10% by mass, step b) is carried out.

9. The method for starting a work according to claim 8, wherein: The volume space velocity of methanol passing through ETBE catalyst is 1-5h -1 .

10. The method for starting a work according to any one of claims 1 to 4, wherein: The mass content of isobutylene in the C4 material is less than 0.5%; and / or The C4 material comes from at least one of the C4 in the oil refining process, the C4 in the ethylene cracking process, the C4 in the methanol to olefins process, the C4 remaining after the etherification reaction to produce MTBE and ETBE, or the light C4 produced by the 1-butene separation device.

11. The method for starting a work according to claim 10, wherein: The mass content of isobutylene in the C4 material is less than 0.1%.

12. The method for starting a work according to any one of claims 1 to 4, wherein: The water content of the fresh ETBE catalyst is 10% to 80% by mass; and / or ETBE catalyst is an ion exchange resin catalyst.

13. The method for starting a work according to claim 12, wherein: ETBE catalyst is a sulfonic acid type cation exchange resin catalyst.

14. The method for starting a work according to any one of claims 2 to 4, wherein: The ETBE device further comprises: an extraction tower (3) and a distillation recovery tower (4); The distillation recovery tower (4) is connected to the reactor (1) and / or the catalytic distillation tower (2) and is used to separate water and methanol from the reactor (1) and / or the catalytic distillation tower (2); The extraction tower (3) is connected to the top of the catalytic distillation tower (2) and is used for extracting and separating the top discharge of the catalytic distillation tower (2).

15. The method for starting a work according to claim 14, wherein: The extractant in the extraction column (3) comprises water.

16. The method for starting a work according to claim 15, wherein: The distillation recovery tower (4) is connected to the extraction tower (3) and is used to return the water separated by the distillation recovery tower (4) to the extraction tower (3) as an extractant.

17. A method for producing ETBE, characterized in that: After the ETBE device is started up using the start-up method described in any one of claims 2 to 16, ethanol and C4 raw materials are introduced into the reactor (1) or the catalytic distillation tower (2) to produce ETBE.

18. The production method according to claim 17, wherein When the methanol content in the discharge materials of the reactor (1) and / or the catalytic distillation tower (2) is less than 3% by mass, ethanol and C4 raw materials are introduced into the reactor (1) to produce ETBE.

19. The production method according to claim 17 or 18, wherein The ETBE device further comprises: an extraction tower (3) and a distillation recovery tower (4); The distillation recovery tower (4) is connected to the reactor (1) and / or the catalytic distillation tower (2) and is used to separate water and methanol from the reactor (1) and / or the catalytic distillation tower (2); The extraction tower (3) is connected to the top of the catalytic distillation tower (2) and is used to extract and separate the top discharge of the catalytic distillation tower (2); Before introducing ethanol and C4 raw materials into the reactor (1) or the catalytic distillation tower (2) to produce ETBE, all materials in the extraction tower (3) and the distillation recovery tower (4) are discharged.

Images