阅读说明：本技术 一种己内酰胺法制备己二胺关键中间体6-氨基己腈的催化剂再生方法 (Catalyst regeneration method for preparing hexamethylene diamine key intermediate 6-aminocapronitrile by caprolactam method ) 是由 王根林 徐林 丁克鸿 刘鑫 王铖 殷恒志 梅学赓 王鑫宇 郭博博 于 2020-06-10 设计创作，主要内容包括：本发明提供了己内酰胺法制备己二胺关键中间体6-氨基己腈的催化剂再生方法。该催化剂再生方法包括：将待再生催化剂进行水解处理或溶解处理,得到再生催化剂。本申请通过对待再生催化剂进行水解处理或溶解处理,使待再生催化剂上的聚合物水解形成己内酰胺等物质或者直接将结焦物质溶解出来,解除了聚合物对催化剂的堵塞,实现了对催化剂的再生处理。上述催化剂再生方法操作简单,易于工业化实施。(The invention provides a catalyst regeneration method for preparing a key intermediate 6-aminocapronitrile of hexamethylene diamine by a caprolactam method. The catalyst regeneration method comprises the following steps: and (3) carrying out hydrolysis treatment or dissolution treatment on the catalyst to be regenerated to obtain the regenerated catalyst. According to the method, the catalyst to be regenerated is hydrolyzed or dissolved, so that polymers on the catalyst to be regenerated are hydrolyzed to form substances such as caprolactam and the like or directly dissolve out coking substances, the blockage of the polymers on the catalyst is removed, and the regeneration treatment of the catalyst is realized. The catalyst regeneration method is simple to operate and easy to implement industrially.)

1. A catalyst regeneration method for preparing a hexamethylene diamine key intermediate 6-aminocapronitrile by a caprolactam method is characterized by comprising the following steps: and (3) carrying out hydrolysis treatment or dissolution treatment on the catalyst to be regenerated to obtain the regenerated catalyst.

2. The catalyst regeneration method according to claim 1, characterized in that the catalyst regeneration method comprises:

and carrying out hydrolysis treatment or dissolution treatment on the catalyst to be regenerated by using water or an aqueous solution, wherein the aqueous solution is selected from one or more of an acidic aqueous solution, an alkaline aqueous solution and a mixture of organic matters and water, the mass content of acidic substances in the acidic aqueous solution is 0.001-10%, the mass content of alkaline substances in the alkaline aqueous solution is 0.001-10%, and the mass content of organic matters in the mixture of the organic matters and the water is 0.1-50%.

3. The method of claim 2, wherein the acidic substance in the acidic aqueous solution is selected from one or more of sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, formic acid, acetic acid, sulfamic acid, glycolic acid, oxalic acid, and citric acid.

4. The method for regenerating a catalyst according to claim 2, wherein the alkaline substance in the alkaline aqueous solution is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, and ethylenediamine.

5. The method of claim 2, wherein the organic substance is selected from one or more of methanol, ethanol, isopropanol, 1, 3-propanediol, acetonitrile, diethyl ether, acetone, tetrahydrofuran, ethylene glycol dimethyl ether, N-dimethylformamide, and dimethylsulfoxide.

6. The method for regenerating a catalyst according to claim 2, wherein the temperature of the hydrolysis or the dissolution is 200 to 500 ℃, preferably 250 to 450 ℃, and the gauge pressure is 0 to 10MPa, preferably 1 to 3 MPa.

7. The catalyst regeneration method according to claim 2, wherein the mass space velocity of the water or the aqueous solution during the hydrolysis treatment or the dissolution treatment is 1 to 20 hours^-1Preferably 3 to 15 hours^-1The hydrolysis time is 1-48 h, preferably 5-35 h.

8. The catalyst regeneration process of claim 1, wherein the hydrolysis treatment also results in a regeneration solution, the catalyst regeneration process further comprising: distilling the regenerated solution to recover caprolactam therein.

9. The method for regenerating a catalyst according to claim 8, wherein the distillation is carried out in a still at a pressure of 0.1 to 10kPa, preferably 1 to 10KPa, and the still temperature is 100 to 250 ℃, preferably 120 to 160 ℃.

10. The catalyst regeneration process of any one of claims 1 to 9, wherein the catalyst regeneration process is an on-line regeneration process.

Technical Field

The invention relates to the technical field of preparation of 6-aminocapronitrile, in particular to a catalyst regeneration method for preparing a key intermediate 6-aminocapronitrile of hexamethylene diamine by a caprolactam method.

Background

1, 6-hexanediamine is an important chemical raw material, is an important intermediate in synthetic materials, and is mainly used for producing nylon 66 by reacting with adipic acid and producing nylon 610 by reacting with sebacic acid, and then preparing various nylon resins, nylon fibers and engineering plastics.

The processes for producing hexamethylenediamine are classified into adiponitrile process, which is a major industrial process, and caprolactam process, which is classified into: butadiene process, acrylonitrile process, adipic acid process.

The butadiene method is to add one molecule of butadiene and two molecules of hydrocyanic acid to obtain adiponitrile and byproducts (methylglutaronitrile and the like); the advantages are low production cost and good product quality; the disadvantages are that virulent hydrocyanic acid is used, the occupational hazard is large, and the construction investment is high. The acrylonitrile method generally adopts a diaphragm-free electrolysis process, acrylonitrile is quantitatively converted into adiponitrile through a primary polymerization stage and a dimerization stage in electrochemical cathode hydrogenation; has the advantages of short process flow; the defects are that the control steps of the electrolysis process are long, the technical nodes are more, the safety risk is high, and explosion happens when the first device (Runxing) in China is tried. The adipic acid method is used for ammoniating and dehydrating adipic acid to generate adiponitrile; the method has the advantages that the technical route is relatively mature, the yield of the raw material adipic acid is excessive, and the price is gradually reduced; the disadvantages are high energy consumption, easy coking of the reactor and poor product quality.

The method for synthesizing hexamethylene diamine by catalytic hydrogenation of adiponitrile has the defects of large separation difficulty and the like due to a plurality of side reaction types and a plurality of impurities.

In the 60 s of the 20 th century, a caprolactam method process technology was developed by Dongli, Japan, and the caprolactam inferior-quality product recovered from waste nylon 6 was used as a raw material, caprolactam and ammonia gas were reacted under the action of a catalyst to obtain 6-aminocapronitrile, and further hydrogenation and refining were carried out to obtain hexamethylenediamine, which is limited by the high price of caprolactam at that time, and the process could not be further popularized, and the production was stopped at present. In recent years, the caprolactam production capacity in China is increasingly surplus, so that the competitiveness of the method is increasingly shown.

The Chinese patent application with the application number of 201710943063.4 discloses a method and a device for preparing 6-aminocapronitrile by a caprolactam liquid phase method, wherein caprolactam, an organic solvent and a catalyst are mixed, and the mixture is reacted with ammonia under the catalysis of phosphoric acid or phosphate to prepare 6-aminocapronitrile.

Application No. 201710942344.8 discloses a process for preparing 6-aminocapronitrile by the gas phase process of caprolactam by mixing caprolactam vapor with hot ammonia gas and reacting the mixture in contact with an alkaline earth metal oxide, a transition metal oxide, silica and an activated alumina catalyst in a fixed bed reactor to produce 6-aminocapronitrile, which does not address the problem of catalyst life or how to address the reduction in catalyst activity during production.

In the process of preparing 6-aminocapronitrile by a caprolactam method, the problem of gradual catalyst deactivation is presented, which is mainly characterized in that the conversion rate of caprolactam and the selectivity of 6-aminocapronitrile are reduced. The main reasons for catalyst deactivation are: in the process of preparing 6-aminocapronitrile from caprolactam, the byproduct is water, the caprolactam is catalyzed to polymerize, the generated polymer blocks the catalyst pore channel, the activity of the catalyst is reduced, in addition, tar is easily generated by high-temperature reaction and covers the surface of the catalyst, and the active sites of the catalyst are further reduced.

Disclosure of Invention

The invention mainly aims to provide a method for regenerating a catalyst for preparing a key intermediate 6-aminocapronitrile of hexamethylene diamine by a caprolactam method, so as to solve the problem that the activity of the catalyst for preparing 6-aminocapronitrile by the caprolactam method in the prior art is reduced along with use.

In order to achieve the above object, according to one aspect of the present invention, there is provided a catalyst regeneration method for preparing 6-aminocapronitrile, a key intermediate of hexamethylenediamine, by a caprolactam process, the catalyst regeneration method comprising: and (3) carrying out hydrolysis treatment or dissolution treatment on the catalyst to be regenerated to obtain the regenerated catalyst.

Further, the above catalyst regeneration method comprises: the catalyst to be regenerated is subjected to hydrolysis treatment or dissolution treatment by water or an aqueous solution, the aqueous solution is selected from one or more of an acidic aqueous solution, an alkaline aqueous solution and a mixture of organic matters and water, the mass content of acidic substances in the acidic aqueous solution is 0.001-10%, the mass content of alkaline substances in the alkaline aqueous solution is 0.001-10%, and the mass content of organic matters in the mixture of the organic matters and the water is 0.1-50%.

Further, the acidic substance in the acidic aqueous solution is selected from one or more of sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, formic acid, acetic acid, sulfamic acid, glycolic acid, oxalic acid and citric acid.

Further, the alkaline substance in the alkaline aqueous solution is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide and ethylenediamine.

Further, the organic substance is selected from one or more of methanol, ethanol, isopropanol, 1, 3-propylene glycol, acetonitrile, diethyl ether, acetone, tetrahydrofuran, ethylene glycol dimethyl ether, N-dimethylformamide and dimethyl sulfoxide.

Further, the temperature of the hydrolysis or dissolution is 200 to 500 ℃, preferably 250 to 450 ℃, and the gauge pressure is 0 to 10MPa, preferably 1 to 3 MPa.

Further, in the hydrolysis treatment process or the dissolution treatment process, the mass space velocity of water or water solution is 1-20 h^-1Preferably 3 to 15 hours^-1The hydrolysis time is 1-48 h, preferably 5-35 h.

Further, the hydrolysis treatment also obtains a regeneration solution, and the catalyst regeneration method also comprises the following steps: the regenerated solution is subjected to a distillation treatment to recover caprolactam therein.

Further, the pressure of the distillation is 0.1 to 10kPa, preferably 1 to 10KPa, the distillation is carried out in a distillation kettle, and the temperature of the distillation kettle is 100 to 250 ℃, preferably 120 to 160 ℃.

Further, the above catalyst regeneration method is an on-line regeneration method.

By applying the technical scheme of the invention, the polymer on the catalyst to be regenerated is hydrolyzed to form substances such as caprolactam and the like or directly dissolves out the coking substance by carrying out hydrolysis treatment or dissolution treatment on the catalyst to be regenerated, so that the blockage of the polymer on the catalyst is removed, and the regeneration treatment of the catalyst is realized. The catalyst regeneration method is simple to operate and easy to implement industrially.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As analyzed by the background art of the present application, in the process of preparing 6-aminocapronitrile by the caprolactam method in the prior art, due to the polymerization and coking of caprolactam and the like, the catalyst pore is blocked, and the activity of the catalyst is reduced, and in order to solve the problem, the present application provides a catalyst regeneration method for preparing a key intermediate 6-aminocapronitrile by the caprolactam method, wherein the catalyst regeneration method comprises: and (3) carrying out hydrolysis treatment or dissolution treatment on the catalyst to be regenerated to obtain the regenerated catalyst.

According to the method, the catalyst to be regenerated is hydrolyzed or dissolved, so that polymers on the catalyst to be regenerated are hydrolyzed to form substances such as caprolactam and the like or directly dissolve out coking substances, the blockage of the polymers on the catalyst is removed, and the regeneration treatment of the catalyst is realized. The catalyst regeneration method is simple to operate and easy to implement industrially.

In an embodiment of the present application, the above catalyst regeneration method includes: the catalyst to be regenerated is subjected to hydrolysis treatment or dissolution treatment in water or an aqueous solution, the aqueous solution is selected from one or more of an acidic aqueous solution, an alkaline aqueous solution and a mixture of an organic substance and water, the mass content of the acidic substance in the acidic aqueous solution is 0.001-10%, the mass content of the alkaline substance in the alkaline aqueous solution is 0.001-10%, and the mass content of the organic substance in the mixture of the organic substance and water is 0.1-50%. The hydrolysis treatment of the present application can be performed in different environments, thus making the catalyst regeneration method of the present application more adaptable.

The acidic aqueous solution that can be used in the hydrolysis treatment of the present application may be any of various organic or inorganic acids commonly used in the art, and preferably the acidic substance in the acidic aqueous solution is one or more selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, formic acid, acetic acid, sulfamic acid, glycolic acid, oxalic acid, and citric acid, and preferably one or more selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid.

The alkaline aqueous solution that can be used for the hydrolysis treatment in the present application may employ various organic or inorganic bases commonly used in the art, and preferably the base in the above alkaline aqueous solution is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, ethylenediamine, preferably ammonia, sodium hydroxide, and more preferably ammonia.

The method utilizes organic matters, removes polymers, tar and the like on the catalyst to be regenerated by utilizing the solubility characteristics of the organic matters to the polymers and tar at high temperature, preferably selects one or more of methanol, ethanol, isopropanol, 1, 3-propylene glycol, acetonitrile, diethyl ether, acetone, tetrahydrofuran, ethylene glycol dimethyl ether, N-dimethylformamide and dimethyl sulfoxide, and preferably selects methanol and acetonitrile.

In order to improve the hydrolysis or dissolution efficiency, the hydrolysis or dissolution temperature is preferably 200 to 500 ℃, preferably 250 to 450 ℃, and the gauge pressure is 0 to 10MPa, preferably 1 to 3 MPa.

In order to improve the utilization efficiency of water or aqueous solution, the mass space velocity of the water or aqueous solution is preferably 1-20 h in the hydrolysis treatment process or the dissolution treatment process^-1Preferably 3 to 15 hours^-1The hydrolysis time is 1-48 h, preferably 5-35 h.

In order to further improve the economic viability of the catalytic regeneration process of the present application, it is preferred that the above catalyst regeneration process further comprises: the regenerated solution is subjected to a distillation treatment to recover caprolactam therein. After the regenerated catalyst is hydrolyzed, the caprolactam formed by hydrolysis is dissolved in the aqueous solution and can be recovered by distillation treatment.

In order to improve the recovery purity of caprolactam, the distillation pressure is preferably 0.1 to 10kPa, and preferably 1 to 10 KPa.

In one embodiment, the distillation is carried out in a distillation kettle, the temperature of the distillation kettle is 100-250 ℃, preferably 120-160 ℃, and the fraction with the gas phase temperature of 60-200 ℃ is collected, preferably 100-140 ℃, so that the recovery of caprolactam can be realized.

The catalyst regeneration method can be an on-line regeneration method, namely, the catalyst for preparing 6-aminocapronitrile is not required to be unloaded from a catalyst bed layer, and the catalyst can be regenerated by directly adding an aqueous solution into the catalyst bed layer and then carrying out hydrolysis treatment on the aqueous solution.

The advantageous effects of the present application will be further described below with reference to examples and comparative examples.

The expression "percent by weight" in the following denotes the weight of caprolactam converted to a content of 100%;

unless otherwise specified, the following contents are all mass percentages.

The catalyst was evaluated as follows:

50g of catalyst are charged in a tubular reactor having an internal diameter of 10mm, caprolactam being present at a mass space velocity of 0.5h^-1And the mol ratio of ammonia gas to caprolactam is 15: 1, the two are fully mixed and then are subjected to catalytic ammoniation reaction in a catalyst bed layer in a tubular reactor at 380 ℃ and 0.5MPa to generate 6-aminocapronitrile, and the caprolactam conversion rate and the 6-aminocapronitrile selectivity are monitored. The conversion per pass of caprolactam is lower than 40 percent or the selectivity of aminocapronitrile is lower than 90 percent, the catalyst is judged to be deactivated and needs to be regenerated, the single pass life of the fresh catalyst is 1600 hours, and the average conversion rate of caprolactam is 49.0 percent and the selectivity of 6-aminocapronitrile is 92.1 percent.