阅读说明：本技术 一种气相法制备6-氨基己腈的模拟移动床装置及方法 (Simulated moving bed device and method for preparing 6-aminocapronitrile by gas phase method ) 是由 王根林 王铖 李良善 丁克鸿 徐林 梅学赓 殷恒志 刘鑫 王鑫宇 陈耀坤 何成义 于 2021-04-14 设计创作，主要内容包括：本发明提供了一种气相法制备6-氨基己腈的模拟移动床装置及方法,所述装置包括至少3级固定床反应器,呈正多边形排列；所述固定床反应器中前面至少两级依次串联连接,构成反应段,最后一级构成再生段；所述固定床反应器绕中心轴间歇旋转,旋转后第一级固定床反应器变为再生段,再生段变为反应段的最后一级固定床反应器。本发明通过反应段和再生段的划分,实现催化剂连续原位再生,克服催化剂停车再生的问题；所述装置中多级固定床反应器的排列及整体旋转,实现了移动床的效果,有利于催化剂循环更新,加之己内酰胺原料的分级加入,有助于提高原料转化率和产品选择性；所述装置结构简单精巧,工艺操作简便,经济效益高,应用前景广阔。(The invention provides a simulated moving bed device and a method for preparing 6-aminocapronitrile by a gas phase method, wherein the device comprises at least 3 stages of fixed bed reactors which are arranged in a regular polygon shape; at least two stages in the front of the fixed bed reactor are sequentially connected in series to form a reaction section, and the last stage forms a regeneration section; the fixed bed reactor intermittently rotates around the central shaft, the first stage fixed bed reactor becomes a regeneration section after the rotation, and the regeneration section becomes the last stage fixed bed reactor of the reaction section. The invention realizes the continuous in-situ regeneration of the catalyst by dividing the reaction section and the regeneration section, and overcomes the problem of shutdown regeneration of the catalyst; the arrangement and the integral rotation of the multistage fixed bed reactors in the device realize the effect of a moving bed, are beneficial to the cyclic updating of the catalyst, and are beneficial to the improvement of the conversion rate of raw materials and the selectivity of products by adding the caprolactam raw materials in stages; the device has the advantages of simple and exquisite structure, simple and convenient process operation, high economic benefit and wide application prospect.)

1. A simulated moving bed device for preparing 6-aminocapronitrile by a gas phase method is characterized by comprising at least 3 stages of fixed bed reactors which are arranged in a regular polygon shape; at least two stages in the front of the fixed bed reactors are connected in series in sequence to form a reaction section, and the fixed bed reactor at the last stage forms a regeneration section; the fixed bed reactor intermittently rotates around the central shaft, the first stage fixed bed reactor becomes a regeneration section after the rotation, and the regeneration section becomes the last stage fixed bed reactor of the reaction section.

2. A simulated moving bed apparatus according to claim 1, wherein the number of stages of the fixed bed reactor in the simulated moving bed apparatus is 3-10 stages;

preferably, a feed inlet is arranged on the first stage fixed bed reactor of the reaction section, and material supplementing ports are arranged on the other fixed bed reactors of the reaction section;

preferably, a discharge hole is formed in the last stage of fixed bed reactor of the reaction section;

preferably, a regeneration gas inlet and a regeneration gas outlet are arranged on the fixed bed reactor of the regeneration section.

3. A simulated moving bed apparatus according to claim 1 or 2, wherein the fixed bed reactors are each packed with a solid phase catalyst;

preferably, the filling volume fraction of the catalyst in the fixed bed reactor is 10-100%;

preferably, the angle of each rotation of the fixed bed reactors is the included angle between the connecting lines of the adjacent two stages of fixed bed reactors and the central shaft;

preferably, after each rotation, the respective connection relationship of the first-stage fixed-bed reactor and the last-stage fixed-bed reactor is changed.

4. A process for the preparation of 6-aminocapronitrile using a simulated moving bed apparatus according to any one of claims 1 to 3, characterized in that it comprises the following steps:

(1) introducing a gaseous mixture of ammonia and part of caprolactam into a first-stage fixed bed reactor, and performing amination dehydration reaction under the action of a catalyst to obtain a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of a reaction section, adding part of caprolactam raw material into each stage of fixed bed reactor, and performing ammoniation dehydration reaction under the action of a catalyst to obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using regenerated gas to obtain a regenerated catalyst;

(4) and (4) rotating the simulated moving bed device around the central shaft at intervals, adjusting the connection relationship, and repeating the steps (1) to (3).

5. The method according to claim 4, characterized in that the caprolactam of the steps (1) and (2) is divided into the same number of stages as the reaction section fixed bed reactors, and one portion is added into each stage of fixed bed reactor;

preferably, the molar ratio of the ammonia gas to the total caprolactam is (3-50): 1, preferably (10-30): 1.

6. The process of claim 4 or 5, wherein the catalyst of steps (1) and (2) comprises an active component comprising phosphoric acid and/or a phosphate salt and a support comprising alumina and/or silica;

preferably, the active component accounts for 0.1-10 wt% of the carrier;

preferably, the active component comprises any one of phosphoric acid, polyphosphoric acid, magnesium phosphate, aluminium phosphate, calcium phosphate or boron phosphate, or a combination of at least two thereof.

7. The method according to any one of claims 4 to 6, wherein the gaseous mixture in step (1) is preheated to form a gaseous state before being introduced into the first-stage fixed bed reactor;

preferably, the temperature of the ammoniation and dehydration reaction in the steps (1) and (2) is 300-500 ℃;

preferably, the pressure of the ammoniation and dehydration reaction in the steps (1) and (2) is 0.1-3 MPa;

preferably, during the ammoniation dehydration reaction in the steps (1) and (2), the weight hourly space velocity of caprolactam added into each stage of fixed bed reactor is 0.1-10 h independently^-1Preferably 0.5 to 5 hours^-1。

8. The method according to any one of claims 4 to 7, wherein the composition of the regeneration gas of step (3) comprises oxygen and nitrogen;

preferably, the volume fraction of oxygen in the regeneration gas in the step (3) is 0.1-50%, preferably 2-20%;

preferably, the temperature of the regeneration treatment in the step (3) is 300-800 ℃;

preferably, the pressure of the regeneration treatment in the step (3) is 0-1 MPa;

preferably, the weight hourly space velocity of the regeneration gas in the step (3) is 0.01-20 h^-1Preferably 0.05 to 3 hours^-1。

9. The process according to any one of claims 4 to 8, wherein the simulated moving bed apparatus is rotated every 200 to 500 hours in step (4);

preferably, the angle of each rotation in the step (4) is a ratio of 360 degrees to the number of fixed bed reactors;

preferably, after each rotation of the step (4), the regeneration section is used as the last fixed bed reactor of the reaction section, the original first fixed bed reactor is used as the regeneration section, and the steps (1) to (3) are repeated.

10. Method according to any of claims 4-9, characterized in that the method comprises the steps of:

(1) introducing a gaseous mixture of ammonia and partial caprolactam into a first-stage fixed bed reactor, wherein the molar ratio of the ammonia to the total caprolactam is (3-50): 1, the partial caprolactam is one of caprolactam equal parts, the equal parts are the same as the stage number of the reaction-section fixed bed reactor, an ammoniation dehydration reaction is carried out under the action of a catalyst, the active component of the catalyst comprises phosphoric acid and/or phosphate, the carrier comprises alumina and/or silica, the temperature of the ammoniation dehydration reaction is 300-500 ℃, the pressure is 0.1-3 MPa, and the weight hourly space velocity measured by the caprolactam is 0.1-10 h^-1Obtaining a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of a reaction section, adding one of caprolactam and other parts into each stage of fixed bed reactor, and performing ammoniation dehydration reaction under the action of a catalyst, wherein the active component of the catalyst comprises phosphoric acid and/or phosphate, the carrier comprises alumina and/or silica, the temperature of the ammoniation dehydration reaction is 300-500 ℃, the pressure is 0.1-3 MPa, and the weight hourly space velocity metered by the caprolactam added into each stage of fixed bed reactor is independently 0.1-10 h^-1To obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using regeneration gas, wherein the regeneration gas comprises oxygen and nitrogen, the volume fraction of the oxygen is 0.1-50%, the temperature of the regeneration treatment is 300-800 ℃, the pressure is 0-1 MPa, and the weight hourly space velocity is 0.01-20 h^-1To obtain a regenerated catalyst;

(4) and (3) rotating the simulated moving bed device once around the central shaft every 200-500 hours, wherein the rotating angle of each time is the ratio of 360 degrees to the number of the fixed bed reactors, adjusting the connection relationship after each rotation, taking the regeneration section as the last fixed bed reactor of the reaction section, taking the original first fixed bed reactor as the regeneration section, and repeating the steps (1) - (3).

Technical Field

The invention belongs to the technical field of organic synthesis, and relates to a simulated moving bed device and a method for preparing 6-aminocapronitrile by a gas phase method.

Background

Hexamethylenediamine is an important chemical product, is mainly used for producing polyamide, synthesizing polyurethane resin, ion exchange resin and diisocyanate, is used as a curing agent of urea resin, epoxy resin and the like, an organic cross-linking agent and the like, can be used as an adhesive, a stabilizer, a bleaching agent, an anti-corrosion agent and the like, and is widely applied to the fields of organic synthesis, aerospace, textile papermaking, metal materials and the like. The main source of the hexamethylene diamine is 6-aminocapronitrile, and the 6-aminocapronitrile is an important chemical intermediate and can be hydrogenated to prepare the hexamethylene diamine, so that the preparation of the 6-aminocapronitrile becomes an important step on a hexamethylene diamine production line.

At present, the synthesis of 6-aminocapronitrile mainly takes caprolactam as a raw material and is prepared by ammoniation dehydration reaction, and the synthesis comprises two major types of gas phase method and liquid phase method; the reaction needs a catalyst, water which is a byproduct of the reaction catalyzes caprolactam to polymerize, the generated polymer blocks catalyst pore channels, the activity of the catalyst is reduced, in addition, tar and carbon deposition are easily generated in high-temperature reaction and cover the surface of the catalyst, the active sites of the catalyst are further reduced, the catalyst is gradually inactivated, and the running stability of a reaction device is poor.

CN 107739318A discloses a method and a device for preparing 6-aminocapronitrile by a caprolactam liquid phase method, which comprises the following steps: s1: mixing caprolactam, an organic solvent and a catalyst to obtain a mixed solution, adding the mixed solution into a reaction kettle, and stirring and heating the mixed solution; s2: when the mixed solution reaches a certain temperature, introducing ammonia gas into the mixed solution for reaction; s3: after the reaction is finished, rectifying and purifying the reaction product to obtain pure 6-aminocapronitrile. The liquid phase method adopts phosphoric acid or phosphate as a catalyst, and the phosphorus-containing catalyst is difficult to recover after being used and does not relate to the regeneration and the utilization of the catalyst; the reaction has higher requirement on the corrosion resistance of equipment, and can generate phosphorus-containing wastewater after rectification, thereby increasing the subsequent treatment operation.

CN 111004148A discloses a method for preparing 6-aminocapronitrile by a gas phase method, which comprises the following steps: respectively preheating caprolactam and ammonia gas after metering, mixing, further heating to obtain a mixture, putting the mixture into a reactor, carrying out an ammoniation dehydration reaction in the presence of a catalyst to obtain an ammoniation reactant, wherein the catalyst consists of alkaline earth metal salt or transition metal salt serving as an active component and titanium dioxide or a ZSM-5 molecular sieve serving as a carrier, and finally separating and purifying to obtain the target product 6-aminocapronitrile. The method still takes reaction and purification as main steps, and does not relate to the regeneration treatment of the catalyst and how to solve the problem of the reduction of the activity of the catalyst.

CN 111646921A discloses a catalyst regeneration method for preparing a hexamethylene diamine key intermediate 6-aminocapronitrile by a caprolactam method, which mainly comprises the step of carrying out hydrolysis treatment or dissolution treatment on a catalyst to be regenerated, wherein the used solution is an acidic solution, an alkaline solution or an organic solution, but the regeneration of the catalyst in the method cannot be carried out synchronously with the reaction, the stable operation time of a reaction device is not improved, and the process involved in the process is complicated and is not beneficial to industrial implementation.

In summary, for the catalytic preparation of 6-aminocapronitrile, it is also necessary to be able to realize the synchronous reaction and catalyst regeneration in the same device, overcome the problem of fast catalyst activity decay, and ensure the long-time continuous operation of the reaction device.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a simulated moving bed device and a simulated moving bed method for preparing 6-aminocapronitrile by a gas phase method, wherein the device enables reaction and regeneration to be synchronously carried out by dividing a reaction section and a regeneration section, overcomes the problem of stopping and regenerating a catalyst, is beneficial to the cyclic updating of the catalyst and prolonging the service life, and simultaneously, the use of a multi-stage fixed bed reactor and the rotation of the device can play the effect of a moving bed, thereby being beneficial to the improvement of the utilization rate of raw materials and the selectivity of products, and further improving the production efficiency.

In order to achieve the purpose, the invention adopts the following technical scheme:

in one aspect, the invention provides a simulated moving bed device for preparing 6-aminocapronitrile by a gas phase method, which comprises at least 3 stages of fixed bed reactors, wherein the fixed bed reactors are arranged in a regular polygon shape; at least two stages in the front of the fixed bed reactors are connected in series in sequence to form a reaction section, and the fixed bed reactor at the last stage forms a regeneration section; the fixed bed reactor intermittently rotates around the central shaft, the first stage fixed bed reactor becomes a regeneration section after the rotation, and the regeneration section becomes the last stage fixed bed reactor of the reaction section.

According to the invention, the multistage fixed bed reactor is adopted to prepare the 6-aminocapronitrile, and the 6-aminocapronitrile is divided into the reaction section and the regeneration section, so that the reaction and the regeneration processes can be synchronously carried out, the problem of stopping and regenerating the catalyst is solved, and the device can continuously run for a long time; the arrangement and the integral rotation of the multistage fixed bed reactors in the device realize the effect of a moving bed, are beneficial to the cyclic updating of the catalyst and the service life of the catalyst, and simultaneously, the staged addition of the raw materials is also beneficial to the improvement of the utilization rate of ammonia gas and the selectivity of products, thereby improving the production efficiency; the device has the advantages of simple and exquisite structural design, simple and convenient operation, obvious effect, high economic benefit and wide application prospect.

The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.

In a preferred embodiment of the present invention, the number of stages of the fixed bed reactor in the simulated moving bed apparatus is 3 to 10, for example, 3, 4, 5, 6, 7, 8, 9, or 10 stages.

Preferably, a feed inlet is arranged on the first-stage fixed bed reactor of the reaction section, and material supplementing ports are arranged on the other fixed bed reactors of the reaction section.

Preferably, a discharge hole is formed in the last stage of fixed bed reactor of the reaction section.

Preferably, a regeneration gas inlet and a regeneration gas outlet are arranged on the fixed bed reactor of the regeneration section.

As a preferable technical scheme of the invention, solid-phase catalysts are filled in the fixed bed reactors.

Preferably, the packed volume fraction of catalyst in the fixed bed reactor is 10 to 100%, such as 10%, 30%, 50%, 60%, 80%, or 100%, but not limited to the recited values, and other values not recited within this range are equally applicable.

Preferably, the angle of each rotation of the fixed bed reactors is the included angle between the connecting lines of the adjacent two stages of fixed bed reactors and the central axis.

Preferably, after each rotation, the respective connection relationship of the first-stage fixed-bed reactor and the last-stage fixed-bed reactor is changed.

In another aspect, the present invention provides a method for preparing 6-aminocapronitrile using the above simulated moving bed apparatus, the method comprising the steps of:

(1) introducing a gaseous mixture of ammonia and part of caprolactam into a first-stage fixed bed reactor, and performing amination dehydration reaction under the action of a catalyst to obtain a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of a reaction section, adding part of caprolactam raw material into each stage of fixed bed reactor, and performing ammoniation dehydration reaction under the action of a catalyst to obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using regenerated gas to obtain a regenerated catalyst;

(4) and (4) rotating the simulated moving bed device around the central shaft at intervals, adjusting the connection relationship, and repeating the steps (1) to (3).

As a preferred technical scheme of the invention, the division parts of the caprolactam in the steps (1) and (2) are the same as the number of stages of a fixed bed reactor in a reaction section, and one part of caprolactam is added into each stage of fixed bed reactor.

Preferably, the molar ratio of ammonia gas to total caprolactam is (3-50): 1, for example 3:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 40:1 or 50:1, but is not limited to the recited values, and other values not recited within this range of values are equally applicable, preferably (10-30): 1.

In the invention, the total caprolactam refers to the addition of caprolactam feeding amount in each stage of fixed bed reactors, the addition amount ratio of caprolactam and ammonia gas as reactants is an important factor influencing the conversion rate of raw materials, if the molar ratio of ammonia gas to caprolactam is lower, namely the addition amount of ammonia gas is less, the conversion rate of raw materials and the selectivity of products are reduced, the activity attenuation of catalysts is accelerated, and if the molar ratio of ammonia gas to caprolactam is higher, namely the addition amount of ammonia gas is more, the consumption of ammonia gas or the energy consumption for recycling ammonia gas is increased, which is not favorable for the process economy.

As a preferred technical scheme of the invention, the catalyst in the steps (1) and (2) comprises an active component and a carrier, wherein the active component comprises phosphoric acid and/or phosphate, and the carrier comprises alumina and/or silica.

Preferably, the active component is present in the carrier in a mass fraction of 0.1 to 10 wt%, such as 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 5 wt%, 7 wt%, 8 wt% or 10 wt%, but not limited to the recited values, and other values not recited within this range are equally applicable.

Preferably, the active ingredient comprises any one of, or a combination of at least two of, phosphoric acid, polyphosphoric acid, magnesium phosphate, aluminum phosphate, calcium phosphate, or boron phosphate, typical but non-limiting examples of which are: combinations of phosphoric acid and magnesium phosphate, polyphosphoric acid and aluminum phosphate, calcium phosphate and boron phosphate, phosphoric acid, magnesium phosphate and aluminum phosphate, phosphoric acid, polyphosphoric acid, aluminum phosphate and calcium phosphate, and the like.

As a preferable technical scheme of the invention, the gaseous mixture in the step (1) is preheated to form a gaseous state before being introduced into the first-stage fixed bed reactor.

In the invention, the caprolactam is in a solid state at normal temperature, and the mixture is in a gaseous state at the reaction temperature, so that preheating is needed first to form a gaseous mixture in advance, and the gaseous mixture can be reacted in a fixed bed reactor.

Preferably, the temperature of the ammoniation and dehydration reaction in the steps (1) and (2) is 300-500 ℃, for example 300 ℃, 320 ℃, 350 ℃, 380 ℃, 400 ℃, 420 ℃, 450 ℃, 480 ℃ or 500 ℃, etc., but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the pressure of the ammoniation dehydration reaction in the steps (1) and (2) is 0.1 to 3MPa, for example, 0.1MPa, 0.2MPa, 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa or 3MPa, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, during the ammoniation dehydration reaction in the steps (1) and (2), the weight hourly space velocity of caprolactam added into each stage of fixed bed reactor is 0.1-10 h independently^-1E.g. 0.1h^-1、0.5h^-1、1h^-1、2h^-1、3h^-1、5h^-1、6h^-1、8h^-1Or 10h^-1And the like, but not limited to the recited values, and other values not recited within the range of the recited values are also applicable, and preferably 0.5 to 5 hours^-1。

In the invention, the reaction temperature, the reaction pressure and the space velocity are important process parameters for reaction, the reaction pressure is measured by gauge pressure, the relevance of the space velocity and the contact time is large, if the space velocity is too low, the productivity of the device is too low, the industrialized implementation is not facilitated, and if the space velocity is too high, the surface of the addition polymerization catalyst is coked, and the service life of the catalyst is shortened.

According to the setting mode of the multistage fixed bed reactor and the feeding mode of caprolactam raw materials, the restriction on the caprolactam weight hourly space velocity comprises two modes, wherein the caprolactam feeding amount of each fixed bed reactor is relative to the space velocity of the catalyst in the fixed bed reactor, the total caprolactam feeding amount is relative to the space velocity of the total catalyst in the device, the two modes can be selected, and the first mode is preferably selected to ensure the controllability of the reaction.

As a preferred technical scheme of the invention, the composition of the regeneration gas in the step (3) comprises oxygen and nitrogen.

Preferably, the volume fraction of oxygen in the regeneration gas in step (3) is 0.1 to 50%, such as 0.1%, 0.5%, 2%, 5%, 10%, 15%, 20%, 30%, 40% or 50%, but not limited to the recited values, and other non-recited values within this range are equally applicable, preferably 2 to 20%.

Preferably, the temperature of the regeneration treatment in step (3) is 300 to 800 ℃, for example 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃ or 800 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the pressure of the regeneration treatment in step (3) is 0 to 1MPa, for example, 0MPa, 0.2MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.8MPa or 1MPa, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the weight hourly space velocity of the regenerated gas in the step (3) is 0.01-20 h^-1E.g. 0.01h^-1、0.05h^-1、0.1h^-1、0.5h^-1、1h^-1、3h^-1、5h^-1、8h^-1、10h^-1、15h^-1Or 20h^-1And the like, but not limited to the recited values, and other values not recited within the range of the recited values are also applicable, and preferably 0.05 to 3 hours^-1。

In the regeneration process of the catalyst, substances such as carbon deposit, tar and the like on the surface of the catalyst are oxidized into carbon dioxide and nitric oxide under the condition of high temperature by mainly utilizing the oxidation action of oxygen, so that active sites in the deactivated catalyst are exposed and are easy to contact with reactants, and the regeneration of the catalyst is realized.

In a preferred embodiment of the present invention, the simulated moving bed apparatus is rotated once every 200 to 500 hours in step (4), for example, 200 hours, 250 hours, 300 hours, 350 hours, 400 hours, 450 hours, or 500 hours, but the present invention is not limited to the above-mentioned values, and other values not shown in the above-mentioned range of values are also applicable.

In the context of the present invention, the choice of the spin interval is based on the effect of the reaction, in particular the degree of reduction of the conversion, in relation to the choice of the catalyst and the process conditions, and is generally bounded by a conversion of less than 95%, below which the spinning is carried out.

Preferably, the angle of each rotation in step (4) is a ratio of 360 degrees to the number of fixed bed reactors.

Preferably, after each rotation of the step (4), the regeneration section is used as the last fixed bed reactor of the reaction section, the original first fixed bed reactor is used as the regeneration section, and the steps (1) to (3) are repeated.

As a preferred technical scheme of the invention, the method comprises the following steps:

(1) introducing a gaseous mixture of ammonia and partial caprolactam into a first-stage fixed bed reactor, wherein the molar ratio of the ammonia to the total caprolactam is (3-50): 1, the partial caprolactam is one of caprolactam equal parts, the equal parts are the same as the stage number of the reaction-section fixed bed reactor, an ammoniation dehydration reaction is carried out under the action of a catalyst, the active component of the catalyst comprises phosphoric acid and/or phosphate, the carrier comprises alumina and/or silica, the temperature of the ammoniation dehydration reaction is 300-500 ℃, the pressure is 0.1-3 MPa, and the weight hourly space velocity measured by the caprolactam is 0.1-10 h^-1Obtaining a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of a reaction section, adding one of caprolactam and other parts into each stage of fixed bed reactor, and performing ammoniation dehydration reaction under the action of a catalyst, wherein the active component of the catalyst comprises phosphoric acid and/or phosphate, the carrier comprises alumina and/or silica, the temperature of the ammoniation dehydration reaction is 300-500 ℃, the pressure is 0.1-3 MPa, and the weight hourly space velocity metered by the caprolactam added into each stage of fixed bed reactor is independently 0.1-10 h^-1To obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using regeneration gas, wherein the regeneration gas comprises oxygen and nitrogen, the volume fraction of the oxygen is 0.1-50%, the temperature of the regeneration treatment is 300-800 ℃, the pressure is 0-1 MPa, and the weight hourly space velocity is 0.01-20 h^-1To obtain a regenerated catalyst;

(4) and (3) rotating the simulated moving bed device once around the central shaft every 200-500 hours, wherein the rotating angle of each time is the ratio of 360 degrees to the number of the fixed bed reactors, adjusting the connection relationship after each rotation, taking the regeneration section as the last fixed bed reactor of the reaction section, taking the original first fixed bed reactor as the regeneration section, and repeating the steps (1) - (3).

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the device, the reaction and regeneration can be synchronously carried out through the division of the reaction section and the regeneration section, so that the continuous in-situ regeneration of the catalyst is realized, the problem of shutdown regeneration of the catalyst is solved, the problem of poor running stability of the device caused by the inactivation of the catalyst is avoided, and the continuous stable running time of the device is up to 4800 h;

(2) the arrangement and the integral rotation of a multistage fixed bed reactor in the device realize the effect of a moving bed, are beneficial to the cyclic updating of the catalyst and prolong the service life of the catalyst, and the staged addition of caprolactam raw materials is beneficial to improving the conversion rate of the caprolactam raw materials, the utilization rate of ammonia gas and the selectivity of products, wherein the conversion rate of the caprolactam can reach more than 95.8 percent, and the selectivity of 6-aminocapronitrile can reach more than 96.2 percent;

(3) the device has simple and exquisite structural design, the fixed bed reactor rotates in sequence, so that the newly regenerated high-activity catalyst is always positioned at the last stage of the reaction section, the activity of the catalyst is gradually increased along the feeding direction of the reaction section, and the plurality of feeding ports can reasonably distribute heat absorption, increase the heat exchange area and ensure that the temperature in the reactor is uniformly distributed;

(4) the device has the advantages of simple structure, simple and convenient process operation, obvious effect, high economic benefit and wide application prospect.

Drawings

FIG. 1 is a schematic structural diagram of a simulated moving bed apparatus for producing 6-aminocapronitrile by a vapor phase process, provided in example 1 of the present invention;

the method comprises the following steps of 1-a first-stage fixed bed reactor, 11-a feeding hole, 2-a second-stage fixed bed reactor, 21-a first material supplementing hole, 3-a third-stage fixed bed reactor, 31-a second material supplementing hole, 32-a discharging hole, 4-a fourth-stage fixed bed reactor, 41-a regeneration gas inlet and 42-a regeneration gas outlet.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.

The invention provides a simulated moving bed device and a method for preparing 6-aminocapronitrile by a gas phase method, wherein the simulated moving bed device comprises at least 3 stages of fixed bed reactors which are arranged in a regular polygon shape; at least two stages in the front of the fixed bed reactors are connected in series in sequence to form a reaction section, and the fixed bed reactor at the last stage forms a regeneration section; the fixed bed reactor intermittently rotates around the central shaft, the first stage fixed bed reactor 1 becomes a regeneration section after the rotation, and the regeneration section becomes the last stage fixed bed reactor of the reaction section.

The method comprises the following steps:

(1) introducing a gaseous mixture of ammonia and part of caprolactam into a first-stage fixed bed reactor 1, and performing amination dehydration reaction under the action of a catalyst to obtain a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of a reaction section, adding part of caprolactam raw material into each stage of fixed bed reactor, and performing ammoniation dehydration reaction under the action of a catalyst to obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using regenerated gas to obtain a regenerated catalyst;

(4) and (4) rotating the simulated moving bed device around the central shaft at intervals, adjusting the connection relationship, and repeating the steps (1) to (3).

The following are typical but non-limiting examples of the invention:

example 1:

the embodiment provides a simulated moving bed device for preparing 6-aminocapronitrile by a gas phase method, which is shown in a schematic structural diagram in figure 1 and comprises four-stage fixed bed reactors arranged in a square shape; the front three stages of the fixed bed reactors are connected in series in sequence and respectively form a first-stage fixed bed reactor 1, a second-stage fixed bed reactor 2 and a third-stage fixed bed reactor 3 to form a reaction section, and a fourth-stage fixed bed reactor 4 to form a regeneration section; the fixed bed reactor intermittently rotates around the central shaft, the first stage fixed bed reactor 1 becomes a regeneration section after the rotation, and the regeneration section becomes the last stage fixed bed reactor of the reaction section.

The reactor is characterized in that a feed inlet 11 is formed in the first-stage fixed bed reactor 1 of the reaction section, and material supplementing ports, namely a first material supplementing port 21 and a second material supplementing port 31, are formed in the second-stage fixed bed reactor 2 and the third-stage fixed bed reactor 3 of the reaction section.

And a discharge port 32 is arranged on the third-stage fixed bed reactor 3 of the reaction section.

The fourth-stage fixed bed reactor 4 is provided with a regeneration gas inlet 41 and a regeneration gas outlet 42.

Solid-phase catalysts are all filled in the fixed bed reactors, and the filling volume fraction of the solid-phase catalysts is 100%.

The angle of each rotation of the fixed bed reactors is the included angle between the connecting line of the two adjacent fixed bed reactors and the central shaft, namely 90 degrees.

After each rotation, the original first-stage fixed bed reactor 1 is not connected with the second-stage fixed bed reactor 2, and the original fourth-stage fixed bed reactor 4 is connected with the third-stage fixed bed reactor 3.

Example 2:

this example provides a simulated moving bed apparatus for the vapor phase process for the preparation of 6-aminocapronitrile, the structure of which is as described in example 1, except that: comprises three-stage fixed bed reactors which are arranged in a regular triangle; the first two stages of fixed bed reactors are connected in series to form a reaction section, and the last stage of fixed bed reactor forms a regeneration section; the filling volume fraction of the solid phase catalyst in the fixed bed reactor is 80 percent; the angle of each rotation of the fixed bed reactor is 120 degrees.

Example 3:

this example provides a simulated moving bed apparatus for the vapor phase process for the preparation of 6-aminocapronitrile, the structure of which is as described in example 1, except that: comprises ten-stage fixed bed reactors which are arranged in a regular decagon shape; the first nine stages of fixed bed reactors are connected in series to form a reaction section, and the last stage of fixed bed reactor forms a regeneration section; the filling volume fraction of the solid phase catalyst in the fixed bed reactor is 10 percent; the angle of each rotation of the fixed bed reactor is 36 degrees.

Example 4:

this example provides a simulated moving bed apparatus for the vapor phase process for the preparation of 6-aminocapronitrile, the structure of which is as described in example 1, except that: comprises six-stage fixed bed reactors which are arranged in a regular hexagon shape; the front five-stage fixed bed reactors are connected in series to form a reaction section, and the last stage fixed bed reactor forms a regeneration section; the filling volume fraction of the solid phase catalyst in the fixed bed reactor is 60 percent; the angle of each rotation of the fixed bed reactor is 60 degrees.

Example 5:

this example provides a gas phase process for the preparation of 6-aminocapronitrile using the simulated moving bed apparatus of example 1, comprising the steps of:

(1) introducing a gaseous mixture of ammonia gas and 1/3 caprolactam into a first-stage fixed bed reactor 1, wherein the molar ratio of the ammonia gas to the total caprolactam is 30:1, carrying out an ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst is aluminum oxide loaded with aluminum phosphate, the aluminum phosphate accounts for 5 wt% of the aluminum oxide, the temperature of the ammoniation dehydration reaction is 400 ℃, the pressure is 0.8MPa, and the weighted hourly space velocity of the caprolactam feeding material relative to the catalyst in the first-stage fixed bed reactor 1 is 2h^-1Obtaining a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of a reaction section, adding 1/3 of the total caprolactam molar weight into each stage of fixed bed reactor, carrying out ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst is the same as that in the first stage of fixed bed reactor 1, the temperature of the ammoniation dehydration reaction is 400 ℃, the pressure is 0.8MPa, and each stage of caprolactam is fed to react with the fixed bed at the stageThe weight hourly space velocity of the catalyst in the reactor is 2h^-1To obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using a regeneration gas, wherein the regeneration gas comprises oxygen and nitrogen, the volume fraction of the oxygen is 2%, the temperature of the regeneration treatment is 400 ℃, the pressure is 0.5MPa, and the weight hourly space velocity is 0.3h^-1Obtaining a regenerated catalyst, and then sequentially replacing the regenerated catalyst with nitrogen and ammonia for later use;

(4) and (3) rotating the simulated moving bed device around the central shaft every 300 hours, wherein the rotating angle is 90 degrees each time, adjusting the connection relationship after each rotation, taking the regeneration section as the last fixed bed reactor of the reaction section, taking the original first fixed bed reactor 1 as the regeneration section, and repeating the steps (1) - (3).

In this example, after the ammoniation dehydration reaction, the conversion rate of caprolactam is 98.8%, and the selectivity of 6-aminocapronitrile is 97.6%; the device can continuously and stably operate for 6000h without obvious attenuation of reaction effect.

Example 6:

this example provides a gas phase process for the preparation of 6-aminocapronitrile using the simulated moving bed apparatus of example 1, comprising the steps of:

(1) introducing a gaseous mixture of ammonia gas and 1/3 caprolactam into a first-stage fixed bed reactor 1, wherein the molar ratio of the ammonia gas to the total caprolactam is 10:1, carrying out an ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst is aluminum oxide loaded with aluminum phosphate, the aluminum phosphate accounts for 2 wt% of the aluminum oxide, the temperature of the ammoniation dehydration reaction is 500 ℃, the pressure is 0.1MPa, and the weighted hourly space velocity of the caprolactam feeding material relative to the catalyst in the first-stage fixed bed reactor 1 is 0.1h^-1Obtaining a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of the reaction section, adding 1/3 of the total caprolactam molar weight into each stage of fixed bed reactor, and carrying out ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst and the catalyst in the first stage of fixed bed reactor 1The temperature of the ammoniation dehydration reaction is 500 ℃, the pressure is 0.1MPa, and the weight hourly space velocity of each caprolactam feeding relative to the catalyst in the fixed bed reactor is 0.1h^-1To obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using a regeneration gas, wherein the regeneration gas comprises oxygen and nitrogen, the volume fraction of the oxygen is 10%, the temperature of the regeneration treatment is 300 ℃, the pressure is 1MPa, and the weight hourly space velocity is 0.05h^-1Obtaining a regenerated catalyst, and then sequentially replacing the regenerated catalyst with nitrogen and ammonia for later use;

(4) and (3) rotating the simulated moving bed device around the central shaft every 400 hours, wherein the rotating angle is 90 degrees every time, adjusting the connection relation after each rotation, taking the regeneration section as the last fixed bed reactor of the reaction section, taking the original first fixed bed reactor 1 as the regeneration section, and repeating the steps (1) - (3).

In this example, after the ammoniation dehydration reaction, the conversion rate of caprolactam is 96.9%, and the selectivity of 6-aminocapronitrile is 96.5%; the device can continuously and stably operate for 5000h without obvious attenuation of reaction effect.

Example 7:

this example provides a gas phase process for the preparation of 6-aminocapronitrile using the simulated moving bed apparatus of example 1, comprising the steps of:

(1) introducing a gaseous mixture of ammonia gas and 1/3 caprolactam into a first-stage fixed bed reactor 1, wherein the molar ratio of the ammonia gas to the total caprolactam is 50:1, carrying out an ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst is silicon dioxide loaded with calcium phosphate, the mass fraction of the calcium phosphate in the silicon dioxide is 8 wt%, the temperature of the ammoniation dehydration reaction is 300 ℃, the pressure is 3MPa, and the weighted hourly space velocity measured by the caprolactam feeding material relative to the catalyst in the first-stage fixed bed reactor 1 is 5h^-1Obtaining a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of the reaction section, wherein total caproic acid is added into each stage of fixed bed reactor1/3 of amine molar weight, the ammoniation dehydration reaction is carried out under the action of a catalyst, the catalyst is the same as the catalyst in the first-stage fixed bed reactor 1, the temperature of the ammoniation dehydration reaction is 300 ℃, the pressure is 3MPa, and the weighted hourly space velocity of each stage of caprolactam relative to the catalyst in the first-stage fixed bed reactor is 5h^-1To obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using a regeneration gas, wherein the regeneration gas comprises oxygen and nitrogen, the volume fraction of the oxygen is 20%, the temperature of the regeneration treatment is 600 ℃, the pressure is 0.2MPa, and the weight hourly space velocity is 3h^-1Obtaining a regenerated catalyst, and then sequentially replacing the regenerated catalyst with nitrogen and ammonia for later use;

(4) and (3) rotating the simulated moving bed device around the central shaft every 500 hours, wherein the rotating angle is 90 degrees each time, adjusting the connection relationship after each rotation, taking the regeneration section as the last fixed bed reactor of the reaction section, taking the original first fixed bed reactor 1 as the regeneration section, and repeating the steps (1) - (3).

In this example, after the ammoniation dehydration reaction, the conversion rate of caprolactam is 99.1%, and the selectivity of 6-aminocapronitrile is 98.6%; the reaction effect of the device is not obviously attenuated when the device continuously and stably operates for 8000 h.

Example 8:

this example provides a gas phase process for the preparation of 6-aminocapronitrile using the simulated moving bed apparatus of example 2, comprising the steps of:

(1) introducing a gaseous mixture of ammonia gas and 1/2 caprolactam into a first-stage fixed bed reactor 1, wherein the molar ratio of the ammonia gas to the total caprolactam is 20:1, carrying out an ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst is alumina loaded with magnesium phosphate, the mass fraction of the magnesium phosphate in the alumina is 0.5 wt%, the temperature of the ammoniation dehydration reaction is 450 ℃, the pressure is 2MPa, and the weighted hourly space velocity of the caprolactam feeding section relative to the catalyst in the first-stage fixed bed reactor 1 is 0.5h^-1Obtaining a reaction mixture;

(2) will be described in step (1)The obtained reaction mixture is sequentially fed into a subsequent fixed bed reactor of the reaction section, 1/2 of the total caprolactam molar weight is added into the fixed bed reactor, an ammoniation dehydration reaction is carried out under the action of a catalyst, the catalyst is the same as that in the first fixed bed reactor 1, the temperature of the ammoniation dehydration reaction is 450 ℃, the pressure is 2MPa, and the weighted hourly space velocity of the caprolactam feeding material relative to the catalyst in the fixed bed reactor is 0.5h^-1To obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using regeneration gas, wherein the regeneration gas comprises oxygen and nitrogen, the volume fraction of the oxygen is 0.5%, the temperature of the regeneration treatment is 800 ℃, the pressure is 0.6MPa, and the weight hourly space velocity is 1h^-1Obtaining a regenerated catalyst, and then sequentially replacing the regenerated catalyst with nitrogen and ammonia for later use;

(4) and (3) rotating the simulated moving bed device around the central shaft every 400 hours, wherein the rotating angle is 120 degrees every time, adjusting the connection relation after each rotation, taking the regeneration section as the last fixed bed reactor of the reaction section, taking the original first fixed bed reactor 1 as the regeneration section, and repeating the steps (1) - (3).

In this example, after the ammoniation dehydration reaction, the conversion rate of caprolactam is 95.8%, and the selectivity of 6-aminocapronitrile is 96.2%; the reaction effect of the device is not obviously attenuated when the device continuously and stably operates for 4800 h.

Example 9:

this example provides a gas phase process for the preparation of 6-aminocapronitrile using the simulated moving bed apparatus of example 3, comprising the steps of:

(1) introducing a gaseous mixture of ammonia gas and 1/9 caprolactam into a first-stage fixed bed reactor 1, wherein the molar ratio of the ammonia gas to the total caprolactam is 40:1, carrying out an ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst is silica loaded with phosphoric acid, the phosphoric acid accounts for 10 wt% of the silica, the temperature of the ammoniation dehydration reaction is 350 ℃, the pressure is 1.2MPa, and the caprolactam feeding of the section is relative to the catalyst in the first-stage fixed bed reactor 1The weight hourly space velocity of the measurement is 8h^-1Obtaining a reaction mixture;

(2) sequentially introducing the reaction mixture obtained in the step (1) into subsequent fixed bed reactors of a reaction section, adding 1/9 of the total caprolactam molar weight into each stage of fixed bed reactor, carrying out ammoniation dehydration reaction under the action of a catalyst, wherein the catalyst is the same as that in the first stage of fixed bed reactor 1, the temperature of the ammoniation dehydration reaction is 350 ℃, the pressure is 1.2MPa, and the weighted hourly space velocity of each stage of caprolactam relative to the catalyst in the stage of fixed bed reactor is 8h^-1To obtain 6-aminocapronitrile;

(3) in the reaction processes of the steps (1) and (2), regenerating the deactivated catalyst in the regeneration section by using a regeneration gas, wherein the regeneration gas comprises oxygen and nitrogen, the volume fraction of the oxygen is 40%, the temperature of the regeneration treatment is 500 ℃, the pressure is 0MPa, and the weight hourly space velocity is 15h^-1Obtaining a regenerated catalyst, and then sequentially replacing the regenerated catalyst with nitrogen and ammonia for later use;

(4) and (3) rotating the simulated moving bed device around the central shaft every 200 hours, wherein the rotating angle is 36 degrees every time, adjusting the connection relation after each rotation, taking the regeneration section as the last fixed bed reactor of the reaction section, taking the original first fixed bed reactor 1 as the regeneration section, and repeating the steps (1) - (3).

In this example, after the ammoniation dehydration reaction, the conversion rate of caprolactam is 99.3%, and the selectivity of 6-aminocapronitrile is 98.8%; the device can continuously and stably operate for 6500h without obvious attenuation of reaction effect.

Comparative example 1:

this comparative example provides a process for the vapor phase preparation of 6-aminocapronitrile using the simulated moving bed apparatus of example 1, with reference to the process of example 6, except that: the molar ratio of ammonia to total caprolactam in step (1) was 1.5: 1.

In this comparative example, the molar ratio of ammonia to caprolactam in the feed was low, i.e. the amount of ammonia added was low, resulting in a decrease in caprolactam conversion and 6-aminocapronitrile selectivity, at which time the caprolactam conversion was reduced to 78.6%, the 6-aminocapronitrile selectivity was reduced to 76.7%, and the continuous steady state plant operation time was reduced to 1600 h.

Comparative example 2:

this comparative example provides a simulated moving bed apparatus and process for the vapor phase preparation of 6-aminocapronitrile, with reference to the apparatus of example 1, except that: the device comprises two stages of fixed bed reactors, wherein one stage is a reaction section, and the other stage is a regeneration section.

The process is referred to the process in example 5, with the only difference that: the operation of the step (2) is not included, and all caprolactam in the step (1) is added into the first-stage fixed bed reactor 1.

In the comparative example, the reaction section of the device only comprises a first-stage fixed bed reactor, caprolactam raw materials cannot be added in a plurality of times, the reaction is not favorably carried out in a grading way, the catalyst is not continuously regenerated, the reaction effect is quickly attenuated, and the conversion rate of caprolactam and the selectivity of 6-aminocapronitrile are quickly reduced; within 900h of operation, the conversion rate of caprolactam is reduced from 98.8 percent to 86.1 percent, the selectivity of 6-aminocapronitrile is reduced from 97.6 percent to 89.6 percent, the stable operation of the device is influenced, and the production efficiency of 6-aminocapronitrile is lower.

It can be seen from the above examples and comparative examples that the apparatus of the present invention, through the division of the reaction section and the regeneration section, allows the reaction and regeneration to be carried out synchronously, realizes the continuous in-situ regeneration of the catalyst, overcomes the problem of catalyst shutdown regeneration, avoids the problem of poor stability of the apparatus operation caused by the deactivation of the catalyst, and has a continuous and stable operation time of 4800 hours or more; the arrangement and the integral rotation of a multistage fixed bed reactor in the device realize the effect of a moving bed, are beneficial to the cyclic updating of the catalyst and prolong the service life of the catalyst, and the staged addition of caprolactam raw materials is beneficial to improving the conversion rate of the caprolactam raw materials, the utilization rate of ammonia gas and the selectivity of products, wherein the conversion rate of the caprolactam can reach more than 95.8 percent, and the selectivity of 6-aminocapronitrile can reach more than 96.2 percent; the device has the advantages of simple and exquisite structural design, simple and convenient process operation, obvious effect, high economic benefit and wide application prospect.

The applicant states that the present invention is illustrated by the detailed apparatus and method of the present invention through the above embodiments, but the present invention is not limited to the above detailed apparatus and method, i.e. it is not meant to imply that the present invention must be implemented by the above detailed apparatus and method. It will be apparent to those skilled in the art that any modifications to the present invention, equivalents of the means for substitution and addition of means for carrying out the invention, selection of specific means, etc., are within the scope and disclosure of the invention.