Method for promoting long-period continuous operation of alkylation main reactor and application thereof

Abstract

The invention discloses a method for promoting long-period continuous operation of an alkylation main reactor and application thereof.The method comprises the steps that a pre-reactor capable of being replaced online is arranged in front of the alkylation main reactor in the material flowing direction, and an aromatic hydrocarbon raw material and an olefin raw material are introduced into the pre-reactor, the discharged material of the pre-reactor enters the alkylation main reactor, and an olefin raw material is independently introduced into the alkylation main reactor at the same time; wherein the pre-reactor is filled with a silicon-aluminum catalyst I, the main reactor is filled with a silicon-aluminum catalyst II, and the silicon-aluminum ratio of the silicon-aluminum catalyst I is smaller than that of the silicon-aluminum catalyst II. The pre-reactor has the function of a protection bed, can indicate the operation state of the protection bed, and ensures the long-period normal operation of the main reactor.

Description

Technical Field

[0001] The invention belongs to the field of alkylation, and in particular relates to the long-term continuous operation of an alkylation main reactor, and specifically relates to a method for promoting the long-term continuous operation of an alkylation main reactor and an application thereof. Background Art

[0002] According to the existing technology, impurities in the benzene raw material in the alkylation reaction can easily poison the catalyst. These substances will further react with the raw material, or block the catalyst pores to destroy the catalyst, or cause the catalyst structure to change, resulting in a decrease in catalyst performance and difficulty in maintaining its life. In order to prevent the catalyst from being affected by poisons such as alkaline nitrides, methanol, and water in the raw material and losing its activity, the current process uses a multi-stage reaction guard bed technology to protect the catalyst in the main reactor.

[0003] However, the existing technology requires continuous detection of the impurity content of the outlet raw materials to determine the state of the adsorbent and regular switching for regeneration. This method of continuous detection of impurities is very cumbersome. The guard bed operation time is often determined by experience. At the same time, the detection of the guard bed setting in the existing technology is prone to errors. Abnormal data requires multiple sampling to confirm the accuracy of the results, which is not real-time enough and easily causes impurities in benzene to enter the main reactor, thereby affecting the activity of the main reactor and causing the main reactor to be unable to operate continuously for a long period of time. Summary of the invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides a method for promoting the long-term continuous operation of an alkylation main reactor and its application, wherein an online replaceable pre-reactor is arranged before the alkylation main reactor, and the pre-reactor can not only remove impurities in the benzene raw material but also has an indication function, and can sensitively detect the deactivation state of the online pre-reactor and replace the pre-reactor in time, which is simple and real-time. In this way, no impurities will enter the alkylation main reactor, and the long-term continuous operation of the alkylation main reactor can be promoted, the frequency of main catalyst replacement is reduced, the multi-stage raw material protection bed is omitted, and the production efficiency of the device is improved.

[0005] On one hand, the present invention provides a method for long-cycle operation of a reactor, comprising: arranging an online replaceable pre-reactor before an alkylation main reactor along the material flow direction, introducing aromatic hydrocarbon feedstock and olefin feedstock into the pre-reactor, the discharge of the pre-reactor enters the alkylation main reactor and olefin feedstock is introduced independently into the alkylation main reactor at the same time; wherein a silicon-aluminum catalyst I is filled in the pre-reactor, a silicon-aluminum catalyst II is filled in the alkylation main reactor, and the silicon-aluminum ratio of the silicon-aluminum catalyst I is less than the silicon-aluminum ratio of the silicon-aluminum catalyst II.

[0006] The pre-reactor has the function of a guard bed and can indicate the operating status of the guard bed to ensure the long-term normal operation of the main reactor.

[0007] The aromatic hydrocarbon raw material is selected from at least one of benzene and toluene.

[0008] The olefin raw material is selected from at least one of propylene, ethylene, butene and long-chain olefins.

[0009] The silicon-aluminum ratio of the silicon-aluminum catalyst II is ≥20.

[0010] The silicon-aluminum ratio of the silicon-aluminum catalyst I is less than or equal to 50% of the silicon-aluminum ratio of the silicon-aluminum catalyst II.

[0011] The olefin space velocity of the pre-reactor is controlled to be lower than the olefin space velocity of the alkylation main reactor.

[0012] Preferably, the olefin space velocity of the pre-reactor is controlled to be less than 50% of the olefin space velocity of the alkylation main reactor.

[0013] More preferably, the olefin space velocity in the pre-reactor is 0.001 to 1.0 h -1 , and / or, the olefin space velocity in the alkylation main reactor is 0.1 to 10 h -1 .

[0014] The molar ratio of the aromatic hydrocarbon feedstock to the olefin feedstock in the alkylation main reactor is 100-2, preferably 30-2.

[0015] The temperature of the alkylation main reactor is controlled to be 130-200°C.

[0016] Preferably, the temperature of the pre-reactor is controlled to be lower than the temperature of the alkylation main reactor.

[0017] More preferably, the difference between the temperature of the pre-reactor and the temperature of the alkylation main reactor is controlled to be ≥5°C.

[0018] The pressures of the pre-reactor and the alkylation main reactor are independently controlled to be 0.1 to 10 MPa, preferably 0.2 to 3.5 MPa.

[0019] The online replaceable pre-reactor is two or more pre-reactors connected in parallel, only one of which is in an online state and connected in series with the alkylation main reactor, and the others are in a standby state.

[0020] Preferably, replacement regeneration is performed when the temperature rise of the online pre-reactor decreases.

[0021] More preferably, when the temperature rise of the online pre-reactor drops to 1 / 4 to 1 / 2 of the temperature rise during initial operation, it is replaced and regenerated.

[0022] The second aspect of the present invention is to provide the application of the method described in the first aspect of the present invention, especially the application in the alkylation reaction of aromatic hydrocarbons, such as the application in the preparation of isopropylbenzene.

[0023] The third aspect of the present invention is to provide an aromatic alkylation reaction method, comprising: carrying out the aromatic alkylation in an alkylation main reactor, and utilizing the method described in the first aspect of the present invention to promote the long-term continuous operation of the alkylation main reactor.

[0024] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the 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 regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The pre-reactor is composed of two or more parallel protection reactors, which can realize online switching and regeneration of the pre-reactor catalyst, and the pre-reactor has an indicator function, so that the alkylation main reactor can be operated continuously for a long period of time, the frequency of main catalyst replacement is reduced, the multi-stage raw material protection bed is omitted, and the production efficiency of the device is improved;

[0027] (2) When applied to the preparation of cumene, the method still has the advantages of high olefin (e.g. propylene) conversion rate and low content of by-products (e.g. n-propylbenzene) in the product (e.g. cumene) after long-term continuous operation. DETAILED DESCRIPTION

[0028] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0029] One of the objects of the present invention is to provide a method for promoting long-term continuous operation of an alkylation main reactor, comprising: arranging an online replaceable pre-reactor before the alkylation main reactor (along the material flow direction), introducing aromatic hydrocarbon feedstock and olefin feedstock into the pre-reactor, the discharge of the pre-reactor entering the alkylation main reactor and simultaneously independently introducing olefin feedstock into the alkylation main reactor; wherein a silicon-aluminum catalyst I is loaded in the pre-reactor, a silicon-aluminum catalyst II is loaded in the alkylation main reactor, and the silicon-aluminum ratio of the silicon-aluminum catalyst I is less than the silicon-aluminum ratio of the silicon-aluminum catalyst II.

[0030] In a preferred embodiment, the aromatic hydrocarbon feedstock is selected from at least one of benzene and toluene; and / or the olefin feedstock is selected from at least one of propylene, ethylene, butene, and long-chain olefins, and the long-chain olefins refer to one or a mixture of several C8 to C18 olefins.

[0031] In a preferred embodiment, the silicon-aluminum ratio of the silicon-aluminum catalyst I is less than or equal to 50% of the silicon-aluminum ratio of the silicon-aluminum catalyst II.

[0032] For example, the silicon-aluminum ratio of the silicon-aluminum catalyst I is less than or equal to 50%, 45%, 40%, 30%, 20% or 10% of the silicon-aluminum ratio of the silicon-aluminum catalyst II.

[0033] Alternatively, the silicon-aluminum ratio of the silicon-aluminum catalyst I is 5% to 50% of the silicon-aluminum ratio of the silicon-aluminum catalyst II, preferably 10% to 50%, for example, any point value among 50%, 45%, 40%, 30%, 20%, 10%, 5%, or a range between any two values.

[0034] Among them, after a large number of experimental studies, the inventors found that the use of a catalyst with a low silicon-to-aluminum ratio as a pre-reactor catalyst has the characteristics of easy deactivation and poor stability, which may be a disadvantage in a common alkylation reaction, but is an advantage in the present invention, because one of the functions of the pre-reactor is an indication function. In this way, the pre-reactor of the present invention uses a low silicon-to-aluminum ratio catalyst that is easy to deactivate and has poor stability, has the advantage of high sensitivity, and the pre-reactor can be replaced in time.

[0035] In a further preferred embodiment, the silicon-aluminum ratio of the silicon-aluminum catalyst II is ≥20, such as 20-100, and more preferably any point value among 20, 25, 30, 35, 40, 60, 80 or 100, or any range consisting of any two points.

[0036] In a further preferred embodiment, the silica-alumina catalyst I is selected from at least one of Y zeolite and ZSM-5 zeolite; and / or the silica-alumina catalyst II is selected from at least one of MWW zeolite and BETA zeolite.

[0037] Among them, the inventors found in a large number of experiments that when Y zeolite and ZSM-5 zeolite are used in the pre-reactor, they are more sensitive and the deactivation of the pre-reactor can be detected more promptly; however, the inventors also found that if MWW zeolite is used for silica-alumina catalyst I, the deactivation of the pre-reactor cannot be detected in time, that is, after a large number of experimental studies, the inventors found that MWW zeolite is not as sensitive as Y zeolite and / or ZSM-5 zeolite when used in the pre-reactor.

[0038] In the present invention, the silica-alumina catalyst I and the silica-alumina catalyst II may optionally contain a binder, and there is no limitation on the content of the binder. For example, the content of the binder in the silica-alumina catalyst I may be greater than, equal to or less than the content of the binder in the silica-alumina catalyst II.

[0039] In a preferred embodiment, the olefin space velocity of the pre-reactor is controlled to be lower than the olefin space velocity of the alkylation main reactor.

[0040] In a further preferred embodiment, the olefin space velocity of the pre-reactor is controlled to be less than 50% of the olefin space velocity of the alkylation main reactor, for example, the olefin space velocity of the pre-reactor is controlled to be 5% to 50% of the olefin space velocity of the alkylation main reactor but not including 50%.

[0041] For example, the propylene space velocity of the pre-reactor is controlled to be less than or equal to any point value among 45%, 40%, 30%, 20% or 10% of the propylene space velocity of the alkylation main reactor, or any range consisting of any two point values.

[0042] In the present invention, the pre-reactor can remove impurities in the aromatic feedstock on the one hand, and on the other hand, a small amount of olefins is introduced into the pre-reactor for a small amount of alkylation reaction, and the purpose of the small amount of alkylation reactor is to play an indicating role. Specifically, when the catalyst in the pre-reactor is close to deactivation due to the removal of impurities in the aromatic feedstock, the deactivation state can be timely discovered or indicated according to the temperature rise of the alkylation reaction in the pre-reactor. In this way, the pre-reactor close to deactivation can be replaced online in time, which will not cause the catalyst of the pre-reactor to be overused, thereby preventing the impurities in the aromatic feedstock from being removed cleanly and entering the alkylation main reactor to affect the long-term operation of the alkylation main reactor.

[0043] In a further preferred embodiment, the olefin space velocity in the pre-reactor is 0.001 to 1.0 h -1 , for example 0.001h -1 , 0.01h -1 , 0.1h -1 、0.2h -1 、0.4h -1 , 0.6h -1 , 0.8h -1 or 1.0h -1 Any point value in or any range consisting of any two point values; and / or, the olefin space velocity in the alkylation main reactor is 0.1 to 10 h -1 , for example 0.1h -1 、0.5h -1 , 1h -1 , 2h -1 , 4h -1, 6h -1 , 8h -1 or 10h -1 Any point value in , or any range of any two point values.

[0044] In a preferred embodiment, the molar ratio of the aromatic hydrocarbon feedstock to the olefin feedstock in the alkylation main reactor is 100-2, preferably 30-2, for example, any point value among 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 5 or 2, or a range consisting of any two values.

[0045] In a preferred embodiment, the temperature of the pre-reactor is controlled to be lower than the temperature of the alkylation main reactor.

[0046] In a further preferred embodiment, the temperature difference between the pre-reactor and the alkylation main reactor is controlled to be ≥5°C, and the preferred temperature difference is 10-50°C, for example, any point value among 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or a range consisting of any two values.

[0047] In a further preferred embodiment, the temperature of the alkylation main reactor is controlled to be 130-200°C, for example, any point value among 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, or a range consisting of any two values.

[0048] Among them, the pre-reactor mainly plays an indicating role. The inventors have found through a large number of experiments that when the pre-reactor is controlled to operate at a temperature lower than that of the main reactor, the pre-reactor performs a low-activity slow reaction, and the temperature rise detection of the pre-reactor is more sensitive and can detect the deactivation of the catalyst in the pre-reactor more timely.

[0049] In a preferred embodiment, the pressures of the pre-reactor and the alkylation main reactor are independently controlled to be 0.1-10 MPa, preferably 0.2-3.5 MPa, for example 0.2 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa or 3.5 MPa.

[0050] In a preferred embodiment, the online replaceable pre-reactor is two or more pre-reactors connected in parallel, only one of which is online and connected in series with the alkylation main reactor, and the others are in standby mode.

[0051] In a further preferred embodiment, the replacement regeneration is performed when the temperature rise of the online pre-reactor decreases.

[0052] The operating state of the catalyst in the online pre-reactor is reflected by the temperature rise of the pre-reactor. During regeneration, the regeneration is carried out by switching, and the main reaction catalyst does not need to be regenerated and can operate stably.

[0053] In a further preferred embodiment, when the temperature rise of the online pre-reactor drops to 1 / 4 to 1 / 2 (eg, one third) of the temperature rise during initial operation, it is replaced and regenerated.

[0054] The regeneration method may be any regeneration method disclosed in the prior art, preferably, but not limited to, a method using hot benzene washing and / or charcoal burning regeneration.

[0055] In the present invention, the pre-reactor can not only remove impurities in the aromatic raw material, but also introduce a small amount of olefins into the pre-reactor to react slowly under low-activity catalyst and low temperature, so as to sensitively monitor the deactivation degree of the catalyst in the pre-reactor. The present invention does not need to continuously detect the impurity content of the outlet raw material, but only needs to judge according to the temperature rise of the pre-reactor, which is simple and efficient.

[0056] A second object of the present invention is to provide an application of the method described in the first object of the present invention in an aromatic hydrocarbon alkylation reaction, such as an application in the preparation of isopropylbenzene.

[0057] The third object of the present invention is to provide an aromatic alkylation reaction method (e.g., a method for preparing isopropylbenzene), comprising: carrying out the aromatic alkylation in an alkylation main reactor, and utilizing one of the methods of the present invention to promote long-term continuous operation of the alkylation main reactor.

[0058] Example

[0059] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0060] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0061] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0062] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0063] [Example 1] Preparation of cumene by alkylation

[0064] The system including a pre-reactor and an alkylation main reactor is used, wherein the pre-reactor is arranged in two parallels, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with Y zeolite with a silicon-aluminum ratio of 9; the alkylation main reactor is filled with Beta zeolite with a silicon-aluminum ratio of 30. Benzene raw material and propylene are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor while propylene is independently introduced into the alkylation main reactor. The weight space velocity of propylene in the pre-reactor is 0.2h -1 The weight space velocity of propylene in the alkylation main reactor is 1.0h -1 The molar ratio of benzene feedstock to propylene in the alkylation main reactor is 2.0; the temperature of the pre-reactor is controlled at 140° C., and the temperature of the alkylation main reactor is controlled at 155° C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0065] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0066] The reactor was operated continuously for 150 days, the propylene conversion rate was greater than 99.99%, and the content of n-propylbenzene in the product cumene was 220 ppm.

[0067] [Example 2]

[0068] The system includes a pre-reactor and an alkylation main reactor, wherein the pre-reactor is arranged in two parallels, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with ZSM-5 zeolite with a silicon-aluminum ratio of 15; the alkylation main reactor is filled with MCM-22 zeolite with a silicon-aluminum ratio of 30. Benzene raw material and propylene are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor while propylene is independently introduced into the alkylation main reactor. The weight space velocity of propylene in the pre-reactor is 0.2h -1 The weight space velocity of propylene in the alkylation main reactor is 2.0h -1 The molar ratio of benzene feedstock to propylene in the alkylation main reactor is 2.0; the temperature of the pre-reactor is controlled at 140° C., and the temperature of the alkylation main reactor is controlled at 155° C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0069] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0070] The reactor was operated continuously for 150 days, the propylene conversion rate was greater than 99.99%, and the content of n-propylbenzene in the product cumene was 260 ppm.

[0071] [Example 3]

[0072] The system includes a pre-reactor and an alkylation main reactor, wherein the pre-reactor is arranged in two parallels, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with Y zeolite with a silicon-aluminum ratio of 5; the alkylation main reactor is filled with MCM-22 zeolite with a silicon-aluminum ratio of 25. Benzene raw material and propylene are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor while propylene is independently introduced into the alkylation main reactor. The weight space velocity of propylene in the pre-reactor is 0.1h -1 The weight space velocity of propylene in the main alkylation reactor is 1.5h -1 The molar ratio of benzene raw material to propylene in the alkylation main reactor is 3.0; the temperature of the pre-reactor is controlled at 120° C., and the temperature of the alkylation main reactor is controlled at 160° C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0073] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0074] The reactor was operated continuously for 150 days, the propylene conversion rate was greater than 99.99%, and the content of n-propylbenzene in the product cumene was 280 ppm.

[0075] [Example 4]

[0076] The system includes a pre-reactor and an alkylation main reactor, wherein the pre-reactor is arranged in two parallels, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with Y zeolite with a silicon-aluminum ratio of 9; the alkylation main reactor is filled with Beta zeolite with a silicon-aluminum ratio of 30. Benzene raw material and n-butene are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor while n-butene is independently introduced into the alkylation main reactor. The weight space velocity of butene in the pre-reactor is 0.2h -1 The weight space velocity of butene in the main alkylation reactor is 0.6h -1The molar ratio of benzene feedstock to n-butene in the alkylation main reactor is 2.0; the temperature of the pre-reactor is controlled at 140° C., and the temperature of the alkylation main reactor is controlled at 155° C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0077] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0078] The reactor was operated continuously for 150 days, with a butene conversion rate of greater than 99.9% and a sec-butylbenzene selectivity of greater than 99%.

[0079] [Example 5]

[0080] The system includes a pre-reactor and an alkylation main reactor, wherein the pre-reactor is arranged in two parallels, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with Y zeolite with a silicon-aluminum ratio of 9; the alkylation main reactor is filled with Beta zeolite with a silicon-aluminum ratio of 30. Toluene raw material and propylene are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor while propylene is independently introduced into the alkylation main reactor. The weight space velocity of propylene in the pre-reactor is 0.1h -1 The weight space velocity of propylene in the main alkylation reactor is 0.5h -1 The molar ratio of toluene raw material to propylene in the alkylation main reactor is 4.0; the temperature of the pre-reactor is controlled at 140° C., and the temperature of the alkylation main reactor is controlled at 165° C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0081] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0082] The reactor was operated continuously for 150 days, and the propylene conversion rate was greater than 99.85%.

[0083] [Example 6]

[0084] The system including a pre-reactor and an alkylation main reactor is used, wherein the pre-reactor is arranged in two parallels, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with Y zeolite with a silicon-aluminum ratio of 5; the alkylation main reactor is filled with MCM-22 zeolite with a silicon-aluminum ratio of 25. Benzene raw material and long-chain olefin (C12) are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor, and long-chain olefin (C12) is independently introduced into the alkylation main reactor. The weight space velocity of the long-chain olefin (C12) in the pre-reactor is 0.05h -1 The weight space velocity of long-chain olefins in the main alkylation reactor is 0.2h -1 The molar ratio of benzene feedstock to long-chain olefins (C12) in the alkylation main reactor is 10.0; the temperature of the pre-reactor is controlled at 150° C., and the temperature of the alkylation main reactor is controlled at 180° C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0085] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0086] The reactor was operated continuously for 150 days, and the conversion rate of long-chain olefins (C12) was greater than 99.99%.

[0087] [Example 7]

[0088] The system including a pre-reactor and an alkylation main reactor is used, wherein the pre-reactor is arranged in two parallel states, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with Y zeolite with a silicon-aluminum ratio of 5; the alkylation main reactor is filled with MCM-22 zeolite with a silicon-aluminum ratio of 20. Benzene raw material and long-chain C14 olefins are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor. At the same time, long-chain olefins (C14) are independently introduced into the alkylation main reactor. The weight space velocity of the long-chain olefin (C14) in the pre-reactor is 0.1h -1 The weight space velocity of long-chain olefins in the main alkylation reactor is 0.2h -1 The molar ratio of benzene feedstock to long-chain C14 olefins in the alkylation main reactor is 20.0; the temperature of the pre-reactor is controlled at 130° C., and the temperature of the alkylation main reactor is controlled at 170° C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0089] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0090] The reactor was operated continuously for 150 days, and the conversion rate of long-chain olefins (C14) was greater than 99.99%.

[0091] [Example 8]

[0092] The system including a pre-reactor and an alkylation main reactor is used, wherein the pre-reactor is arranged in two parallels, one of which is in an online state and the other is in a standby state. The pre-reactor is filled with Y zeolite with a silicon-aluminum ratio of 9; the alkylation main reactor is filled with Beta zeolite with a silicon-aluminum ratio of 30. Benzene raw material and long-chain olefin (C16) are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor, and long-chain olefin (C16) is independently introduced into the alkylation main reactor. The weight space velocity of the long-chain olefin (C16) in the pre-reactor is 0.1h -1 The weight space velocity of long-chain olefins (C16) in the alkylation main reactor is 0.3h -1 The molar ratio of benzene feedstock to long-chain olefins (C16) in the alkylation main reactor is 30.0; the temperature of the pre-reactor is controlled at 140°C, and the temperature of the alkylation main reactor is controlled at 195°C. The pressures of the pre-reactor and the main reactor are controlled at 3.0 MPa.

[0093] When it is detected that the temperature rise of the online pre-reactor is lower than one third of the temperature rise at the initial cut-in, the pre-reactor is cut out for regeneration and the standby pre-reactor is cut in, and the alkylation main reactor does not need to be switched.

[0094] The reactor was operated continuously for 150 days, and the conversion rate of long-chain olefins (C16) was greater than 99.99%.

[0095] [Comparative Example 1]

[0096] The process of Example 1 was repeated, except that Beta zeolite was filled in the pre-reactor and other conditions remained unchanged.

[0097] The reactor was operated continuously for 150 days, the propylene conversion rate dropped to 99.45%, and the content of n-propylbenzene in the product cumene was 410 ppm.

[0098] [Comparative Example 2]

[0099] The process of Example 1 was repeated, except that the temperature of the pre-reactor was the same as that of the alkylation main reactor, both being 155° C., and other conditions remained unchanged.

[0100] The reactor was operated continuously for 150 days, the propylene conversion rate was greater than 99.99%, and the content of n-propylbenzene in the product cumene was 590 ppm. The high temperature of the pre-reactor showed a higher content of impurity n-propylbenzene.

[0101] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for promoting long-term continuous operation of an alkylation main reactor, comprising: An online replaceable pre-reactor is arranged before the alkylation main reactor along the material flow direction, and aromatic feedstock and olefin feedstock are introduced into the pre-reactor, and the discharge of the pre-reactor enters the alkylation main reactor, and olefin feedstock is independently introduced into the alkylation main reactor at the same time; wherein a silicon-aluminum catalyst I is filled in the pre-reactor, and a silicon-aluminum catalyst II is filled in the alkylation main reactor, and the silicon-aluminum ratio of the silicon-aluminum catalyst I is smaller than the silicon-aluminum ratio of the silicon-aluminum catalyst II.

2. The method according to claim 1, characterized in that: The aromatic hydrocarbon raw material is selected from at least one of benzene and toluene; and / or the olefin raw material is selected from at least one of propylene, ethylene, butene and long-chain olefins.

3. The method according to claim 1, characterized in that The silicon-aluminum ratio of the silicon-aluminum catalyst II is ≥20. Preferably, the silicon-aluminum ratio of the silicon-aluminum catalyst I is less than or equal to 50% of the silicon-aluminum ratio of the silicon-aluminum catalyst II.

4. The method according to claim 1, characterized in that: The olefin space velocity of the pre-reactor is controlled to be less than the olefin space velocity of the alkylation main reactor; preferably, the olefin space velocity of the pre-reactor is controlled to be less than 50% of the olefin space velocity of the alkylation main reactor; more preferably, the olefin space velocity in the pre-reactor is 0.001 to 1.0 h -1 , and / or, the olefin space velocity in the alkylation main reactor is 0.1 to 10 h -1 .

5. The method according to claim 1, characterized in that The molar ratio of the aromatic hydrocarbon feedstock to the olefin feedstock in the alkylation main reactor is 100-2, preferably 30-2.

6. The method according to claim 1, characterized in that The temperature of the alkylation main reactor is controlled to be 130-200° C., and preferably, the temperature of the pre-reactor is controlled to be lower than the temperature of the alkylation main reactor.

7. The method according to claim 1, characterized in that The pressures of the pre-reactor and the alkylation main reactor are independently controlled to be 0.1 to 10 MPa, preferably 0.2 to 3.5 MPa.

8. The method according to any one of claims 1 to 7, characterized in that: The online replaceable pre-reactor is two or more pre-reactors connected in parallel, only one of which is in an online state and connected in series with the alkylation main reactor, and the others are in a standby state; preferably, the online pre-reactor is replaced and regenerated when the temperature rise of the online pre-reactor decreases; more preferably, the online pre-reactor is replaced and regenerated when the temperature rise drops to 1 / 4 to 1 / 2 of the temperature rise during initial operation.

9. Use of the method according to any one of claims 1 to 8, especially in the alkylation reaction of aromatic hydrocarbons, such as in the preparation of cumene.

10. An aromatic hydrocarbon alkylation reaction method, comprising: The aromatic hydrocarbon alkylation is carried out in an alkylation main reactor, and the method according to any one of claims 1 to 8 is used to promote the long-term continuous operation of the alkylation main reactor.