CN109534954B

CN109534954B - Method and device for coproducing cyclohexanol and ethanol

Info

Publication number: CN109534954B
Application number: CN201710858415.6A
Authority: CN
Inventors: 温朗友; 宗保宁; 纪洪波; 慕旭宏; 杜泽学; 马东强; 杨克勇
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-09-21
Filing date: 2017-09-21
Publication date: 2022-02-08
Anticipated expiration: 2037-09-21
Also published as: CN109534954A

Abstract

The invention relates to a method and a device for coproducing cyclohexanol and ethanol, wherein the method comprises the following steps: (1) a step of producing cyclohexyl acetate by reacting acetic acid with a cyclohexene raw material; (2) removing acetic acid in a cyclohexane raw material by using cyclohexanol through catalytic distillation, and simultaneously manufacturing cyclohexyl acetate; (3) a step of purifying cyclohexyl acetate; (4) a step of producing cyclohexanol and ethanol by hydrogenating cyclohexyl acetate; and (5) a step of purifying cyclohexanol and ethanol. The invention can not only recycle the acetic acid-containing cyclohexane material flow with high efficiency, but also adjust the ethanol yield by the acid-olefin ratio conveniently.

Description

Method and device for coproducing cyclohexanol and ethanol

Technical Field

The invention relates to a method and a device for coproducing cyclohexanol and ethanol, in particular to a method and a device for coproducing cyclohexanol and ethanol through acid alkene esterification, alcohol acid esterification and ester hydrogenation.

Background

Cyclohexanol and ethanol are important chemical feedstocks and solvents. Cyclohexanol is mainly used for producing nylon 6, nylon 66 and the like, while ethanol is a raw material for synthesizing various chemical products such as esters and the like, and is also widely used as a fuel additive of gasoline.

The industrial method for synthesizing ethanol is mainly an ethylene direct hydration method, but in some countries rich in agricultural and sideline products, a fermentation method is still the main method for producing ethanol. Because of the large population and insufficient cultivated land area in China, the fermentation method for preparing the ethanol has the problem of 'competing for grains with the mouth', so the fermentation method does not accord with the national situation of China. In addition, the contamination of the fermentation process is also relatively severe. China has relatively insufficient petroleum resources, and the ethylene price is greatly influenced by the fluctuation of international oil prices, so that the ethylene hydration method applied in China faces certain raw material cost pressure. In addition, the reaction conditions of the direct ethylene hydration process are severe and need to be carried out at high temperature and high pressure. In view of the above, the development of new ethanol synthesis process routes is a necessary requirement for technical and economic development.

CN1022228831A discloses a catalyst for preparing ethanol by acetic acid gas phase hydrogenation, which comprises three parts of a main active component, an auxiliary agent and a carrier; the carrier is any one of active carbon, graphite or multi-wall carbon nano-tubes, the main active component is any one or two of metal W or Mo, and the auxiliary agent is one or more of Pd, Re, Pt, Rh or Ru; the content of the main active component is 0.1-30.0% of the weight of the catalyst, the content of the auxiliary agent is 0.1-10.0% of the weight of the catalyst, and the balance is the carrier.

CN102149661A discloses a method for the direct selective production of ethanol from acetic acid using a platinum/tin catalyst, comprising: contacting a feed stream comprising acetic acid and hydrogen at an elevated temperature with a hydrogenation catalyst comprising a group of platinum and tin on a suitable catalyst support and optionally a third metal supported on said support, wherein said third metal is selected from the group consisting of: palladium, rhodium, ruthenium, rhenium. Iridium, chromium, copper, molybdenum, tungsten, vanadium, and zinc.

Industrially, cyclohexanol is produced mainly by a cyclohexane air oxidation process, a phenol hydrogenation process and a cyclohexene hydration process, and among them, the cyclohexane oxidation process is most commonly used.

Cyclohexane oxidation is currently the predominant cyclohexanol production process. The process utilizes an oxidant (generally air) to oxidize cyclohexane into cyclohexyl hydroperoxide, and the cyclohexyl hydroperoxide is decomposed to obtain a mixture of cyclohexanol and cyclohexanone (commonly known as KA oil). The process has the advantages of mild oxidation process conditions, less slag bonding and long continuous operation period. The method has the defects of long process route, high energy consumption and great pollution, and the cyclohexane conversion rate of the process is only 3-5%; particularly, in the decomposition process of cyclohexyl hydroperoxide, the selectivity of cyclohexanol is poor, and the yield is low; in addition, the process also generates a large amount of waste lye which is difficult to treat, and is still a worldwide environmental protection problem.

The phenol hydrogenation method is a cleaner technical route for producing cyclohexanol, and has the advantages of short process flow, high product purity and the like. The cyclohexanol is prepared by hydrogenating phenol through a gas phase hydrogenation method. The method generally adopts 3-5 reactors connected in series. Under the action of a supported Pd catalyst, the yield of cyclohexanone and cyclohexanol can reach 90-95% at 140-170 ℃ and 0.1 MPa. However, this process requires the vaporization of phenol (heat of vaporization 69 kJ. mol)^–1) And methanol (heat of vaporization 35.2 kJ. mol)^–1) The energy consumption is high, the catalyst is easy to deposit carbon in the using process to cause activity reduction, and in addition, the phenol is in short supply and expensive, and a noble metal catalyst is used, so that the industrial application of the method is limited.

In the 80 s of the 20 th century, the japan asahi chemical company developed the process of making cyclohexene from partial hydrogenation of benzene and making cyclohexanol from hydration of cyclohexene, and realized industrialization in 1990, and related chinese patent applications were CN 1079727A, CN 1414933a and CN 101796001A. The cyclohexene hydration method is a relatively new cyclohexanol production method, the reaction selectivity of the method is high, three wastes are hardly discharged in the process, but the defects of low reaction conversion rate, high requirement on cyclohexene purity and the like exist. If high-silicon ZSM-5 catalyst is adopted and stays in two series slurry reactors for 2 hours, the cyclohexene conversion rate is only 12.5 percent.

The cyclohexene esterification-ester hydrogenation process is a new method for co-producing cyclohexanol and ethanol, and related documents can be found in CN103664530A, CN103664529B, CN103664586B, CN103664587B, CN103880598B, CN103880599B, CN103664531B and US 9561991B 2. In these documents, mixtures of cyclohexane and acetic acid are mentioned, but no efficient separation of acetic acid from cyclohexane is mentioned. Although cyclohexane and acetic acid are the basic organic compounds that are very commonly used, there are few reports in the open literature of techniques for separating the two. Cyclohexane has an atmospheric boiling point of 80.1 ℃ and acetic acid has an atmospheric boiling point of 117 ℃ and seems to be easily separated by ordinary rectification, but actually the two form the lowest azeotrope and cannot be separated by ordinary rectification.

CN1270578A/US6177053B1 (method and apparatus for removing acetic acid from cyclohexane in adipic acid production, RPC company) discloses a method and apparatus for removing acetic acid from cyclohexane in the production process of direct oxidation of cyclohexane to adipic acid. The removal of acetic acid is preferably carried out by using a small amount of washing water in a one-to three-stage (preferably two-stage) extraction tank. Although the method can remove acetic acid in cyclohexane; however, the subsequent separation of acetic acid and water is very difficult, and the energy consumption of common rectification and azeotropic rectification adopted in the current industrial separation of water and acetic acid is very high.

It is well known that acetic acid can react with a variety of alcohols to produce a variety of acetates for a wide variety of uses. Since the esterification reaction is a chemical equilibrium reaction, complete conversion of acetic acid cannot be achieved with conventional techniques. Catalytic distillation is a technology developed in the beginning of the last eighties, and couples reaction and distillation in a tower to be carried out simultaneously, so that the chemical equilibrium limit is broken through possibly, and the complete conversion of a certain reactant is realized.

Although a number of references have been published to the production of acetates by catalytic distillation, these references have never addressed the presence of significant levels of naphthenes in the reaction feed. Among the acetic acid esters which have been produced by catalytic distillation, methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate, ethylene glycol acetate and the like are commonly included, and among them, the technology for producing ethyl acetate and n-butyl acetate has been industrially applied, and CN101306994A, CN102134919B, CN1446791A, CN106748758A, CN1036648C, CN103724195A and the like are found in the related patent documents. The removal of acetic acid from cyclohexane by the techniques disclosed in these documents does not directly yield high purity cyclohexane.

Disclosure of Invention

In the existing process for coproducing cyclohexanol and ethanol, a cyclohexane material flow containing more acetic acid is generated, and in order to improve the overall benefit of the process, the material flow must be recycled, but the acetic acid and the cyclohexane can form the lowest azeotrope, so that the separation of the acetic acid and the cyclohexane is very difficult. The main object of the present invention is to provide a process for the co-production of cyclohexanol and ethanol which makes efficient use of the aforementioned cyclohexane stream containing a high amount of acetic acid. To this end, it must be solved, on the one hand, to completely remove the acetic acid from this stream, so that the cyclohexane can be subsequently used, for example for the production of benzene by dehydrogenation; on the other hand, additional separation steps, in particular difficult separation steps, are to be avoided.

The inventors have found in practice that the acetic acid content in the azeotrope of cyclohexane and acetic acid is much higher than the data reported in the literature (2 w%). For such azeotrope, if alcohol is used as raw material and a catalytic distillation technology is used for separation, a complex system of at least five components is formed in a catalytic distillation tower, which is difficult to achieve the purpose of the present invention, such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, glycerol, 2-ethoxyethanol, 2-methoxypropanol, etc., no matter how the operation is performed, the purpose of the present invention cannot be achieved. After diligent efforts, the present inventors have found that, if cyclohexanol is used to perform esterification reaction with acetic acid in cyclohexane raw material in a catalytic distillation column, acetic acid in cyclohexane raw material can be completely removed, and high purity cyclohexyl acetate can be obtained at the same time. Surprisingly, when an extraction section is additionally arranged above a reaction section, even under the condition that the feeding molar ratio of cyclohexanol to acetic acid is close to 1:1, the acetic acid can be easily and completely converted, so that the operation energy consumption can be greatly reduced, and the production efficiency of the process can be obviously improved. Based on these findings, the present inventors have further completed the present invention.

The main contents of the present invention are as follows.

1. A process for co-producing cyclohexanol and ethanol, comprising the steps of:

(6) a step of producing cyclohexyl acetate by reacting acetic acid with a cyclohexene raw material; the cyclohexene feedstock consists of cyclohexene, cyclohexane and optionally benzene;

(7) removing acetic acid in a cyclohexane raw material by using cyclohexanol through catalytic distillation to obtain cyclohexane with the purity of more than 95 percent, and simultaneously manufacturing cyclohexyl acetate; the cyclohexane feed consists of cyclohexane, acetic acid and optionally benzene and/or cyclohexene; the purity of the cyclohexane is calculated by the total mass fraction of benzene, cyclohexene and cyclohexane;

(8) a step of purifying cyclohexyl acetate;

(9) a step of producing cyclohexanol and ethanol by hydrogenating cyclohexyl acetate; and

(10) a step of purifying cyclohexanol and ethanol;

wherein steps (1) to (5) are carried out in the manner A or in the manner B (preferably in the manner A),

mode A:

in the step (1), a catalytic rectifying tower is adopted, so that a cyclohexane raw material and a first crude cyclohexyl acetate material flow are obtained;

in step (2), the cyclohexane raw material is from step (1), and the cyclohexanol is from step (5), so as to obtain a second crude cyclohexyl acetate stream;

in step (3), the first and second crude cyclohexyl acetate streams from steps (1), (2) are combined and separated, thereby obtaining a purified cyclohexyl acetate stream;

in the step (4), hydrogenating the cyclohexyl acetate stream obtained in the step (3) to obtain a crude cyclohexanol and ethanol stream;

in step (5), the crude cyclohexanol and ethanol stream obtained in step (4) is separated, thereby obtaining purified cyclohexanol and ethanol, and a portion of the purified cyclohexanol is used in step (2);

mode B:

in the step (1), a catalytic rectifying tower is not adopted, so that a product material flow containing acetic acid, cyclohexane and cyclohexyl acetate is obtained;

in step (2), the cyclohexane feed comes from step (3) and the cyclohexanol comes from step (5), thereby obtaining a third crude cyclohexyl acetate stream;

in step (3), the product stream from step (1) is combined with the third crude cyclohexyl acetate stream from step (2) and separated, thereby obtaining a cyclohexane feed and a purified cyclohexyl acetate stream;

in step (5), the crude cyclohexanol and ethanol stream obtained in step (4) is separated, thereby obtaining purified cyclohexanol and ethanol, and a portion of the purified cyclohexanol is used in step (2).

2. The method according to any one of the above aspects, wherein the mass fraction of acetic acid in the cyclohexane raw material is 1% to 70% (preferably 5% to 50%, more preferably 10% to 35%, and still more preferably 10% to 20%).

3. A process according to any one of the preceding claims, characterized in that the cyclohexane feed is an azeotrope of cyclohexane and acetic acid or an azeotrope of cyclohexane, acetic acid and cyclohexene and/or benzene.

4. The method according to any one of the preceding claims, characterized in that the cyclohexane raw material contains 0 to 10% by mass of benzene and 0 to 20% by mass of cyclohexene (generally, 0.2 to 1% by mass of benzene and 0.5 to 2% by mass of cyclohexene).

5. A process according to any one of the preceding claims, characterized in that step (2) is carried out in accordance with mode (I) or mode (II),

mode (I): in a catalytic rectifying tower, a cyclohexane raw material and cyclohexanol are in countercurrent contact, so that acetic acid in the cyclohexane raw material and the cyclohexanol are subjected to esterification reaction and removed, and cyclohexane with the purity of more than 95% is obtained from the tower top;

mode (II): the method is carried out in an extractive catalytic distillation tower, and the tower comprises a distillation section, an extraction section, a reaction section and a stripping section from top to bottom; and the cyclohexane raw material enters from the upper part (preferably the upper end) of the extraction section and is in countercurrent contact with cyclohexanol entering from the lower part (preferably the lower end) of the reaction section, so that acetic acid and cyclohexanol in the cyclohexane raw material are subjected to esterification reaction and removed, and cyclohexane with the purity of more than 95% is obtained from the top of the tower.

6. The method according to claim 5, wherein in the mode (I), the number of theoretical plates of the catalytic distillation column is 10 to 150, and the catalyst is arranged between 1/3 and 2/3 (preferably, the number of theoretical plates is 30 to 100, and the catalyst is arranged between 1/3 and 2/3).

7. The process according to

claim

5 or 6, wherein in the mode (I), the molar ratio of the feeding amount of the alcohol to the feeding amount of the acetic acid in the cyclohexane raw material is 1:1 to 10:1 (preferably 1:1 to 2:1, more preferably 1.01:1 to 1.1:1, further preferably 1.01:1 to 1.08:1, and further preferably 1.04:1 to 1.06: 1).

8. The method according to 5, characterized in that in the mode (II), in the extractive catalytic distillation column, the number of theoretical plates in the distillation section is 10 to 50, the number of theoretical plates in the extraction section is 10 to 50, the number of theoretical plates in the reaction section is 10 to 50, and the number of theoretical plates in the stripping section is 10 to 50.

9. The method according to 5 or 8, wherein in the mode (II), the molar ratio of the feeding amount of the alcohol to the feeding amount of the acetic acid in the cyclohexane raw material to be separated is 1:1 to 10:1 (preferably 1:1 to 2:1, more preferably 1:1 to 1.1:1, further preferably 1:1 to 1.02:1, and further preferably 1:1 to 1.01: 1).

10. The method according to any one of claims 5 to 9, wherein in the modes (I) and (II), the reflux ratio is 0.1:1 to 100:1 (preferably 0.5:1 to 10:1, more preferably 0.5:1 to 3:1, and further preferably 1:1 to 2.5: 1).

11. The method according to any one of claims 5 to 10, wherein in the modes (I) and (II), the operating conditions are as follows: the operating pressure is-0.0099 MPa to 5.0MPa, the temperature of a catalyst bed layer is 50 ℃ to 200 ℃, and the feeding space velocity of acetic acid to the total loading amount of the catalyst is 0.2h^-1～20h^-1(the operation conditions are preferably that the operation pressure is normal pressure to 1.0MPa, the temperature of a catalyst bed layer is 60 ℃ to 120 ℃, and the space velocity of acetic acid to the total loading amount of the catalyst is 0.5h^-1～5h^-1)。

12. The process according to any one of claims 5 to 11, characterized in that in the modes (I) and (II), the content of acetic acid in the cyclohexane obtained from the top of the column is less than 50ppm (preferably less than 20ppm, more preferably less than 10ppm, further preferably less than 5ppm) by mass.

13. The process according to any of the claims 5 to 12, characterized in that in the modes (I) and (II), the acetic ester having a purity of more than 90% by mass fraction (the purity of the acetic ester is preferably more than 92.5%, more preferably more than 95%, further preferably more than 97%, further preferably more than 98.5%, more preferably more than 99%, further preferably more than 99.5% by mass fraction) is obtained from the bottom of the column.

14. The method according to any one of the preceding claims, characterized in that in the modes (i) and (ii), the esterification catalyst used is selected from one or more of a combination of strongly acidic ion exchange resin (preferably macroporous sulfonic acid type polystyrene-divinylbenzene resin or halogen atom modified sulfonic acid type resin), heteropoly acid (preferably heteropoly acid and/or heteropoly acid acidic salt, or catalyst loaded heteropoly acid and/or heteropoly acid acidic salt; more preferably heteropoly acid with keggin structure and/or heteropoly acid acidic salt with keggin structure, or catalyst loaded heteropoly acid with keggin structure and/or heteropoly acid acidic salt with keggin structure), and molecular sieve (preferably H beta, HY or HZSM-5).

15. A process according to any one of the preceding claims, characterized in that said cyclohexane having a purity of more than 95% is used in a dehydrogenation reaction to produce benzene and said benzene is used in the production of said cyclohexene starting material.

16. The device for coproducing cyclohexanol and ethanol is characterized by comprising an acid alkene esterification reaction unit, an alcohol acid esterification reaction unit, a cyclohexyl acetate purification unit, a cyclohexyl acetate hydrogenation unit and an ester hydrogenation product separation unit;

the acid alkene esterification reaction unit is used for reacting acetic acid with cyclohexene raw materials to prepare cyclohexyl acetate;

the alcohol acid esterification reaction unit is used for reacting cyclohexanol with cyclohexane raw material, removing acetic acid in the cyclohexane raw material, obtaining cyclohexane with purity of more than 95%, and simultaneously preparing cyclohexyl acetate;

the cyclohexyl acetate purification unit is used for separating and purifying cyclohexyl acetate manufactured by the acid alkene esterification reaction unit and the alkyd esterification reaction unit;

the cyclohexyl acetate hydrogenation unit is used for hydrogenating the purified cyclohexyl acetate to produce cyclohexanol and ethanol;

the ester hydrogenation product separation unit is used for separating and purifying the cyclohexanol and ethanol obtained by the cyclohexyl acetate hydrogenation unit.

17. The apparatus according to claim 16, wherein the alkyd esterification reaction unit comprises at least one catalytic distillation column or one extractive catalytic distillation column.

18. The apparatus according to 16 or 17, further comprising a unit for producing benzene by dehydrogenation of said cyclohexane having a purity of greater than 95% and producing said cyclohexene feed from said benzene.

The invention has the following beneficial technical effects.

Firstly, the invention can completely remove the acetic acid in the cyclohexane raw material only by one catalytic rectifying tower or one extraction catalytic rectifying tower, and directly obtain the high-purity cyclohexane, so that the cyclohexane can be directly used for dehydrogenation to prepare benzene or used for other purposes.

Secondly, the invention can directly obtain the high-purity acetate only by one catalytic rectifying tower or one extraction catalytic rectifying tower, thereby obviously reducing the difficulty of subsequent separation.

Thirdly, the invention can make alcohol and acid completely react according to the stoichiometric reaction, thereby improving the production efficiency of the process for coproducing cyclohexanol and ethanol.

Fourthly, the invention can increase the yield of the ethanol which is more expensive than acetic acid and flexibly adjust the yield.

Drawings

FIG. 1 is a schematic flow chart of the present invention.

Fig. 2 is a flow chart of a pilot plant constructed in accordance with the present invention.

FIG. 3 is a schematic flow diagram of an alkyd esterification model test device employing a catalytic rectification column.

FIG. 4 is a schematic flow diagram of an alkyd esterification model test device employing an extractive catalytic distillation column.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Detailed Description

The present invention is described in detail with reference to the specific embodiments, but it should be understood that the scope of the present invention is not limited by the specific embodiments or the principle of the present invention, but is defined by the claims.

In the present invention, any matter or thing which is not mentioned is directly applicable to what is known in the art without any change except what is explicitly described. Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or ideas thus formed are considered part of the original disclosure or original description of the present invention, and should not be considered as new matters not disclosed or contemplated herein, unless a person skilled in the art would consider such combination to be clearly unreasonable.

All features disclosed in this invention may be combined in any combination and such combinations are understood to be disclosed or described herein unless a person skilled in the art would consider such combinations to be clearly unreasonable. The numerical points disclosed in the present specification include not only the numerical points specifically disclosed in the examples but also the endpoints of each numerical range in the specification, and ranges in which any combination of the numerical points is disclosed or recited should be considered as ranges of the present invention.

Technical and scientific terms used herein are to be defined only in accordance with their definitions, and are to be understood as having ordinary meanings in the art without any definitions.

In the present invention, "optionally" means either with or without A, for example "optionally A" means either with or without A.

In the present invention, the "catalyst" may be defined by the context and should be understood in the clear sense; otherwise, it refers to a solid acid catalyst.

In the present invention, when a technical feature or a combination of technical features is referred to, if it does not indicate an applicable step or mode, it means that the technical feature or the combination of technical features is applicable to all possible steps or modes unless it is obvious or unreasonable to those skilled in the art.

The invention provides a method for coproducing cyclohexanol and ethanol, which comprises the following steps:

(1) a step of producing cyclohexyl acetate by reacting acetic acid with a cyclohexene raw material; the cyclohexene feedstock consists of cyclohexene, cyclohexane and optionally benzene;

(2) removing acetic acid in a cyclohexane raw material by using cyclohexanol through catalytic distillation to obtain cyclohexane with the purity of more than 95 percent, and simultaneously manufacturing cyclohexyl acetate; the cyclohexane feed consists of cyclohexane, acetic acid and optionally benzene and/or cyclohexene; the purity of the cyclohexane is calculated by the total mass fraction of benzene, cyclohexene and cyclohexane;

(3) a step of purifying cyclohexyl acetate;

(4) a step of producing cyclohexanol and ethanol by hydrogenating cyclohexyl acetate; and

(5) a step of purifying cyclohexanol and ethanol;

wherein the steps (1) to (5) are carried out in the manner A or the manner B,

mode A:

mode B:

Step one, preparing acetic acid cyclohexyl ester by reaction of acetic acid and cyclohexene raw material

The method comprises the steps of preparing cyclohexyl acetate by reacting acetic acid with cyclohexene raw material; the cyclohexene feed consists of cyclohexene, cyclohexane and optionally benzene. This procedure is described in detail in CN103664530A, CN103664529B, CN103664586B, CN103664587B, CN103880598B, CN103880599B, CN103664531B, and US 9561991B2, the entire contents of which are incorporated herein by reference as if directly recited in this specification in full.

The cyclohexene is generally prepared by selective hydrogenation of benzene, and the product stream is a mixture of cyclohexene, cyclohexane and benzene, wherein the content of cyclohexene is generally 20 m% -60 m%, if benzene is separated by extraction, a stream with the content of cyclohexene of generally 40 m% -80 m% can be obtained.

In this step, a reaction system comprising one or more reactors may be used. The reactor type can be one or more selected from a kettle type reactor, a fixed bed reactor, a catalytic distillation reaction tower, an ebullated bed reactor and a fluidized bed reactor. The reaction system is preferably a fixed bed reactor or a catalytic rectification tower, and more preferably a fixed bed and a catalytic rectification reaction tower which are connected in series in sequence; wherein the fixed bed reactor is preferably a tubular fixed bed reactor.

The present step is carried out as in mode a, i.e. using a catalytic rectification column, whereby a cyclohexane feed and a first crude cyclohexyl acetate stream are obtained. The cyclohexane raw material directly obtained in the mode A is used in the step (2), on one hand, acetic acid in the cyclohexane raw material is thoroughly removed, and high-purity cyclohexane is obtained; on the other hand, cyclohexyl acetate of high purity is simultaneously produced. The purity of the cyclohexyl acetate in the first crude cyclohexyl acetate stream obtained in mode a can generally reach more than 99%, but in order to improve the catalyst life in the subsequent process, the first crude cyclohexyl acetate stream still needs to be sent to the step (3) for purification, and heavy components are separated from the first crude cyclohexyl acetate stream.

If the step is carried out by the mode B, namely the catalytic rectifying tower is not adopted, so that the product material flow containing the acetic acid, the cyclohexane and the cyclohexyl acetate is obtained, at the moment, the conversion rate of the cyclohexene can generally reach more than 80 percent, and the selectivity of the esterification reaction can reach more than 99 percent. The cyclohexane feed cannot be obtained directly, and the product stream obtained therefrom is sent to the step (3) for separation, thus obtaining purified cyclohexyl acetate and cyclohexane feed.

Secondly, removing acetic acid in the cyclohexane raw material by using cyclohexanol through catalytic distillation to obtain cyclohexane with the purity of more than 95 percent and simultaneously manufacturing cyclohexyl acetate

According to the method, cyclohexanol is used for removing acetic acid in cyclohexane raw materials through catalytic distillation to obtain cyclohexane with the purity of more than 95%, and the step of preparing cyclohexyl acetate is carried out at the same time; the cyclohexane feed consists of cyclohexane, acetic acid and optionally benzene and/or cyclohexene; the purity of the cyclohexane is based on the total mass fraction of benzene, cyclohexene and cyclohexane.

In this step, the mass fraction of acetic acid in the cyclohexane raw material is 1% to 70%, preferably 5% to 50%, more preferably 10% to 35%, and still more preferably 10% to 20%.

In the step, the cyclohexane raw material is an azeotrope of cyclohexane and acetic acid, or an azeotrope of cyclohexane, acetic acid and cyclohexene and/or benzene.

In this step, the cyclohexane feedstock is generally composed of cyclohexane and acetic acid, and sometimes contains a small amount of benzene and/or cyclohexene. Generally, the mass fraction of benzene is 0-10%, and the mass fraction of cyclohexene is 0-20%; furthermore, the mass fraction of benzene is 0.2-1%, and the mass fraction of cyclohexene is 0.5-2%.

The alkyd esterification reaction is a reversible equilibrium reaction, and the equilibrium conversion rate is related to the type of alcohol used, but generally is difficult to exceed 80%. In order to remove acetic acid from cyclohexane raw material, it is necessary to take measures from the process to increase the conversion rate of acetic acid.

It has been found that certain low boiling alcohols and certain high boiling alcohols, such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, glycerol, 2-ethoxyethanol, 2-methoxypropanol, and the like, are not suitable for removing acetic acid from cyclohexane by catalytic distillation.

According to the process of the invention, modes A and B specify the source of the starting materials for this step, such as performing this step using mode A, the cyclohexane starting material coming from step (1), the cyclohexanol coming from step (5), thereby obtaining a second crude cyclohexyl acetate stream; the present step is carried out as in mode B, the cyclohexane feed comes from step (3) and the cyclohexanol comes from step (5), thus obtaining a third crude cyclohexyl acetate stream.

The modes (I) and (II) define the mode of operation of the process according to the invention.

The mode (I) adopts a catalytic rectifying tower. In a catalytic rectifying tower, a cyclohexane raw material and cyclohexanol are in countercurrent contact, so that acetic acid and cyclohexanol in the cyclohexane raw material are subjected to esterification reaction and removed, and cyclohexane with the purity of more than 95% is obtained from the top of the tower.

In the mode (I), the theoretical plate number of the catalytic distillation tower is 10-150, and a catalyst is arranged between 1/3 and 2/3 theoretical plates. The preferable scheme is as follows: the number of theoretical plates is 30-100, and a catalyst is arranged between 1/3 and 2/3 theoretical plates.

In the mode (i), the molar ratio of the feeding amount of the alcohol to the feeding amount of the acetic acid in the cyclohexane raw material is 1:1 to 10:1, preferably 1:1 to 2:1, more preferably 1.01:1 to 1.1:1, further preferably 1.01:1 to 1.08:1, and further preferably 1.04:1 to 1.06: 1.

The mode (II) adopts an extraction catalytic rectification tower, and the tower comprises a rectification section, an extraction section, a reaction section and a stripping section from top to bottom. And the cyclohexane raw material enters from the upper part (preferably the upper end) of the extraction section and is in countercurrent contact with cyclohexanol entering from the lower part (preferably the lower end) of the reaction section, so that acetic acid and cyclohexanol in the cyclohexane raw material are subjected to esterification reaction and removed, and cyclohexane with the purity of more than 95% is obtained from the top of the tower.

In the mode (II), in the extractive catalytic distillation column, the number of theoretical plates in the distillation section is 10-50, the number of theoretical plates in the extraction section is 10-50, the number of theoretical plates in the reaction section is 10-50, and the number of theoretical plates in the stripping section is 10-50.

In the mode (ii), the molar ratio of the feeding amount of the alcohol to the feeding amount of the acetic acid in the cyclohexane raw material to be separated is 1:1 to 10:1 (preferably 1:1 to 2:1, more preferably 1:1 to 1.1:1, further preferably 1:1 to 1.02:1, and further preferably 1:1 to 1.01: 1).

In the embodiments (I) and (II), the reflux ratio is 0.1:1 to 100:1 (preferably 0.5:1 to 10:1, more preferably 0.5:1 to 3:1, and further preferably 1:1 to 2.5: 1).

In both modes (I) and (II), the operating conditions are: the operating pressure is-0.0099 MPa to 5.0MPa, the temperature of a catalyst bed layer is 50 ℃ to 200 ℃, and the feeding space velocity of acetic acid to the total loading amount of the catalyst is 0.2h^-1～20h^-1. The operating conditions are preferably: the operation pressure is normal pressure to 1.0MPa, the temperature of a catalyst bed layer is 60 to 120 ℃, and the space velocity of acetic acid to the total loading amount of the catalyst is 0.5h^-1～5h^-1。

In the modes (I) and (II), the content of acetic acid in the cyclohexane obtained from the top of the column is less than 50ppm by mass (preferably less than 20ppm, more preferably less than 10ppm, further preferably less than 5 ppm).

In the modes (I) and (II), an acetic ester having a purity of more than 90% by mass fraction (the purity of the acetic ester is preferably more than 92.5%, more preferably more than 95%, further preferably more than 97%, further preferably more than 98.5%, more preferably more than 99%, further preferably more than 99.5% by mass fraction) is obtained from the bottom of the column.

In the modes (I) and (II), cyclohexane having a purity of more than 95%, preferably more than 97%, more preferably more than 99%, and further preferably more than 99.5% is obtained from the top of the column.

In the modes (i) and (ii), the esterification catalyst used is selected from one or more of a strong-acid ion exchange resin (preferably macroporous sulfonic acid type polystyrene-divinylbenzene resin or halogen atom modified sulfonic acid type resin), a heteropoly acid (preferably heteropoly acid and/or heteropoly acid acidic salt, or a catalyst supporting heteropoly acid and/or heteropoly acid acidic salt), more preferably heteropoly acid with keggin structure and/or heteropoly acid acidic salt with keggin structure, or a catalyst supporting heteropoly acid with keggin structure and/or heteropoly acid acidic salt with keggin structure), and a molecular sieve (preferably H β, HY or HZSM-5).

The strong-acid ion exchange resin comprises common macroporous sulfonic acid type polystyrene-diethylbenzene resin and sulfonic acid type resin modified by halogen atoms. Such resins are readily available commercially or can be prepared according to classical literature methods. The preparation method is that the mixture of styrene and divinyl benzene is dripped into a water phase system containing dispersant, initiator and pore-forming agent under the condition of high-speed stirring for suspension copolymerization, the obtained polymer small ball (white ball) is separated from the system, the pore-forming agent is extracted by using solvent, dichloroethane is used as solvent and concentrated sulfuric acid is used as sulfonating agent for sulfonation reaction, and finally the strongly acidic ion exchange resin is prepared through the procedures of filtering, washing and the like. Halogen atoms, such as fluorine, chlorine, bromine and the like, are introduced into a benzene ring of a skeleton of the common strong acid type ion exchange resin, so that the temperature resistance and the acid strength of the resin can be further improved. The halogen-containing strongly acidic high-temperature-resistant strongly acidic resin can be obtained by at least the following two routes. One approach is to introduce halogen atoms, such as chlorine atoms, into the benzene ring of the sulfonated styrene resin skeleton, so that the strong electron-withdrawing effect of the halogen elements not only stabilizes the benzene ring, but also improves the acidity of the sulfonic acid groups on the benzene ring, so that the acid strength of the resin catalyst can reach above-8H 0, and the resin can be used for a long time at above 150 ℃, and such resins can be purchased from the market, such as Amberlyst 45 resins produced by foreign ROHM & HASS companies, D008 resins produced by domestic north Hebei Ji chemical plants, and the like. Another class of high temperature and strong acid resistant resins are perfluorosulfonic acid type resins, which have an ultra-strong acidity and ultra-high thermal stability due to the strong electron withdrawing property of fluorine, with an acid strength of H0 of-12 and a heat resistance temperature of 250 ℃ or higher, and are typically Nafion resins produced by DuPont.

The heteropoly acid catalyst can be heteropoly acid and/or heteropoly acid acidic salt, and can also be a catalyst for supporting heteropoly acid and/or heteropoly acid acidic salt. Heteropolyacids andthe acid strength H0 of the acid salt can reach-13.15, and the acid salt can be used for a long time at the temperature of more than 300 ℃. The heteropoly acid comprises heteropoly acids with Kegin structure, Dawson structure, Anderson structure and Silverton structure. Preference is given to heteropolyacids of keggin structure, such as dodecaphosphotungstic acid (H)₃PW₁₂O₄₀·xH₂O), dodecasilicotungstic acid (H)₄SiW₁₂O₄₀·xH₂O), dodecaphosphomolybdic acid (H)₃PMo₁₂O₄₀·xH₂O), dodecaphosphomolybdovanadic acid (H)₃PMo_12-yV_yO₄₀·xH₂O), and the like. The heteropolyacid acidic salt is preferably acidic cesium phosphotungstate (Cs)_2.5H_0.5P₁₂WO₄₀) The acid H0 is less than-13.15, and the specific surface area can reach 100m²More than g. The carrier loaded with heteropoly acid or heteropoly acid acidic salt can be selected from SiO₂And/or activated carbon.

The molecular sieve catalyst comprises one or more of H, HY and HSZM-5, and the acidity and catalytic performance of the molecular sieve can be further improved by means of modification of fluorine, phosphorus and the like.

In the present invention, the form of the catalytic distillation column is not particularly limited. The form of the catalytic rectifying tower is the same as that of a common rectifying tower, and the catalytic rectifying tower comprises a tower body, a tower top condenser, a reflux tank, a reflux pump, a tower kettle, a reboiler and the like; the difference from the common rectifying tower is that the catalytic rectifying tower is provided with a catalyst. The catalytic rectification column can be a plate column, a packed column or a combination of the two. Types of tray columns that can be used include valve columns, sieve tray columns, bubble cap columns, and the like. The packed tower can adopt random packing such as pall ring, theta ring, saddle-shaped packing or step ring packing, and can also adopt regular packing such as corrugated plate packing or corrugated wire mesh packing. The tower internals of the catalytic rectification tower must be made of acetic acid corrosion resistant materials, and the tower internals made of titanium are preferably selected.

In the present invention, the catalyst needs to be arranged in a certain manner in the catalytic distillation column. The arrangement mode at least meets the following two requirements: (1) sufficient channels for vapor-liquid two-phase passage are provided, or the bed porosity is relatively large (generally more than 50 percent is required), so that the vapor-liquid two-phase can pass through in a convection way without causing flooding; (2) for good mass transfer properties, the reactants are transferred from the fluid phase into the catalyst for reaction and the reaction products are transferred from the catalyst, preferably with the reaction medium being in direct contact with the catalyst. Various arrangements of catalysts in reactive distillation columns have been disclosed in the literature and may be employed in the present invention. The arrangement of the existing catalyst in the reaction tower can be summarized into the following three types: (1) directly arranging the catalyst in the tower in a rectification packing manner, wherein the main manner is to mechanically mix catalyst particles with certain size and shape with the rectification packing, or clamp the catalyst between the regular packing to form an integral packing with the regular packing, or directly prepare the catalyst into the shape of the rectification packing; (2) the catalyst is filled into a small container which is permeable to gas and liquid and is arranged on a tower plate of the reaction tower, or the catalyst is arranged in a downcomer of the reaction tower; (3) the catalyst is directly loaded into the reaction tower in a fixed bed mode, the liquid phase directly flows through the catalyst bed layer, and a special channel is established for the gas phase. The liquid on the tower tray enters the next catalyst bed layer through a down-flow pipe and a redistributor, and carries out addition reaction in the bed layer, and the liquid at the lower part of the catalyst bed layer enters the next tower tray through a liquid collector.

In this step, the extractive catalytic distillation column (referred to as a column body) is composed of a distillation section, an extraction section, a reaction section and a stripping section from top to bottom in sequence, and is additionally equipped with distillation column auxiliary equipment such as a column top condenser, a reflux tank, a reflux pump, a column kettle, a reboiler and the like. The tower internals of the extractive catalytic distillation tower must be made of acetic acid corrosion resistant materials, and the tower internals made of titanium are preferably selected.

In the step, in the extractive catalytic distillation column, separation trays such as float valves, sieve plates, bubble caps and the like can be arranged in the distillation section, the extraction section and the stripping section, and various loose or regular fillers such as pall rings, theta rings, saddle-shaped fillers, stepped ring fillers, corrugated plate fillers, corrugated wire mesh fillers and the like can also be filled in the extractive catalytic distillation column. The rectifying section, the extracting section and the stripping section must have a certain number of theoretical plates, and generally speaking, in the extraction catalytic rectifying tower, the number of the theoretical plates of the rectifying section is 10-50, the number of the theoretical plates of the extracting section is 10-50, and the number of the theoretical plates of the stripping section is 10-50.

In the step, the extraction reaction rectification process is basically the same as the catalytic rectification esterification process, but an extraction section is additionally arranged between the reaction section and the rectification section of the catalytic rectification tower, and cyclohexanol enters from the upper part (preferably the upper end) of the extraction section. The inventors have discovered that, by adding an extraction stage, acetic acid in cyclohexane can be completely reacted and converted to cyclohexyl acetate even with an almost stoichiometric amount of cyclohexanol.

The purpose of this step is, on the one hand, to completely remove the acetic acid in the cyclohexane starting material directly produced in step (1) or indirectly obtained from steps (1) and (3) by recycling part of the cyclohexanol product, thus obtaining high-purity cyclohexane, which can be subsequently utilized; on the other hand, the yield of ethanol can be increased.

According to the present invention, the cyclohexane having a purity of more than 95% (preferably more than 97%, more preferably more than 99%, and further preferably more than 99.5%) is used for the dehydrogenation reaction to produce benzene, and the benzene is used for producing the cyclohexene raw material.

Step three, purifying cyclohexyl acetate

The process according to the invention comprises a step of purifying cyclohexyl acetate. Although high purity cyclohexyl acetate can be directly obtained in both the mode A of the step (1) and the step (2), in order to improve the catalyst life in the subsequent hydrogenation step, it is necessary to purify the cyclohexyl acetate obtained in the mode A of the step (1) and the step (2) to remove heavy components.

According to the method of the invention, a separation unit consisting of 1-3 rectifying towers can be adopted in the step. The number of rectifying columns required to be provided is specified by the modes a and B. If the method A is adopted, namely the catalytic rectifying tower is adopted as a reactor in the step (1), the high-purity cyclohexyl acetate can be directly obtained in the step (1), and only one rectifying tower is needed to be arranged in the step for separating the cyclohexyl acetate from heavy components, so that the purified cyclohexyl acetate is obtained. If the method B is adopted, namely the step (1) does not adopt a catalytic distillation tower as a reactor, the product stream of the step (1) generally consists of cyclohexane (containing a small amount of cyclohexene and benzene), acetic acid, cyclohexanol, cyclohexyl acetate and heavy components. One scheme is as follows: and (3) two rectifying towers are set, the first rectifying tower is used for separating cyclohexane and acetic acid from cyclohexanol, cyclohexyl acetate and heavy components, the cyclohexane and the acetic acid are sent to the step (2) for alcohol acid esterification, and the second rectifying tower is used for removing the heavy components in the cyclohexanol and the cyclohexyl acetate. The other scheme is as follows: three rectifying towers are arranged, wherein the first rectifying tower is used for separating cyclohexane (containing azeotropic acetic acid) and sending the cyclohexane to the step (2) for alcohol acid esterification reaction; the second rectifying tower separates and removes acetic acid, send it to step (1) to carry on the esterification reaction of acid alkene; the third rectifying tower is used for removing the heavy components of cyclohexanol and cyclohexyl acetate.

In the step, light and heavy components in the raw materials in the step are removed, and cyclohexyl acetate or cyclohexyl acetate and cyclohexanol are reserved.

Step four of hydrogenation preparation of cyclohexanol and ethanol from cyclohexyl acetate

The method comprises a step of hydrogenation of cyclohexyl acetate to prepare cyclohexanol and ethanol. This procedure is described in detail in CN103664530A, CN103664529B, CN103664586B, CN103664587B, CN103880598B, CN103880599B, CN103664531B, and US 9561991B2, the entire contents of which are incorporated herein by reference as if directly recited in this specification in full.

According to the method, in the step, the purified cyclohexyl acetate is fed into an ester hydrogenation reactor for hydrogenation reaction. The ester hydrogenation reactor is one or more, and the reactor type is selected from one or more of a kettle type reactor, a fixed bed reactor, an ebullating bed reactor and a fluidized bed reactor. The fixed bed reactor is preferably a tubular fixed bed reactor, and more preferably a shell-and-tube reactor.

The ester hydrogenation reactor is filled with an ester hydrogenation catalyst. In this step, the ester hydrogenation catalyst may be one or more selected from a copper-based catalyst, a ruthenium-based catalyst and a noble metal-based catalyst, and is preferably a copper-based catalyst, more preferably a zinc-containing copper-based catalyst and/or a chromium-containing copper-based catalyst.

The ester hydrogenation reaction may be operated in a batch manner or may be carried out in a continuous manner. The batch reaction generally adopts a reaction kettle as a reactor, the cyclohexyl acetate and the hydrogenation catalyst are put into the reaction kettle, hydrogen is introduced to react at a certain temperature and pressure, and after the reaction is finished, the reaction product is discharged from the reaction kettle, the product is separated, and then the next batch of material is put into the reaction kettle to react. The continuous hydrogenation reaction can adopt a shell-and-tube reactor, the hydrogenation catalyst is fixed in the shell-and-tube reactor, and the exothermic heat of the reaction is removed by cooling water on the shell side.

The hydrogenation reaction temperature of the cyclohexyl acetate is related to the selected hydrogenation catalyst, and for the copper-based hydrogenation catalyst, the general hydrogenation reaction temperature is 150-400 ℃, and the optimized reaction temperature is 200-300 ℃. The reaction pressure is normal pressure to 20MPa, and the optimized pressure is 4 to 10 MPa.

Control of the hydrogen-ester mole ratio of cyclohexyl acetate hydrogenation reactions is also important. A high hydrogen-to-ester ratio favors the hydrogenation of the ester, but too high a hydrogen-to-ester ratio will increase the energy consumption of the hydrogen compression cycle. The general hydrogen-ester ratio is 1-1000: 1, and the optimized conditions are 5-100: 1.

the feeding space velocity of the hydrogenation reaction ester is related to the activity of the selected catalyst. Higher space velocities can be used with high activity catalysts. For the selected catalyst, the reaction conversion decreases with increasing space velocity of the reaction. In order to meet a certain conversion, the space velocity must be limited to a certain range. The liquid feed space velocity of the ester is generally 0.1h^－1～20h^－1The optimized condition is 0.2h^－1～2h^－1. If the batch reaction is adopted, the reaction time is 0.5 to 20 hours, preferably 1 to 5 hours.

Fifthly, purifying the cyclohexanol and the ethanol

The method according to the invention comprises a step of purifying cyclohexanol and ethanol. This procedure is described in detail in CN103664530A, CN103664529B, CN103664586B, CN103664587B, CN103880598B, CN103880599B, CN103664531B, and US 9561991B2, the entire contents of which are incorporated herein by reference as if directly recited in this specification in full.

According to the process of the present invention, this step is carried out in an ester hydrogenation product separation system comprising at least one knock-out pot, and a rectification column, an extractive rectification column, or a combination thereof. And (3) allowing the ester hydrogenation product to enter a gas-liquid separation tank for gas-liquid separation, wherein the gas phase is mainly hydrogen and is recycled after being compressed by a compressor. The liquid phase product mainly contains ethanol and cyclohexanol, and may also contain certain amount of ethyl acetate and cyclohexanone, and may also contain certain amount of unreacted cyclohexyl acetate and small amount of heavy boiling matter (polyketone), and these mixture is separated through rectification and/or extractive rectification. The present invention preferably separates the ester hydrogenation product by rectification. The rectification can adopt a batch scheme or a continuous flow scheme. And (3) intermittent rectification, namely putting the ester hydrogenation product into a rectification tower kettle, distilling out ethanol, ethyl acetate, cyclohexanol, cyclohexanone and cyclohexyl acetate from the tower top in sequence, and leaving a small amount of high-boiling-point substances in the tower kettle. Batch distillation can separate a plurality of components by using one tower, but the product quality is unstable and the processing capacity is low due to frequent switching operation, and the batch distillation is usually used in laboratories or small-scale product production. The present invention further preferably employs continuous rectification for the separation of the esterification product. Continuous rectification requires the use of a series of columns to separate the various components. The invention can design various separation processes according to the separation sequence of each component, and the invention preferably selects the process scheme of sequential separation, namely, a hydrogenation product separation system is sequentially provided with a gas-liquid separation tank for separating hydrogen, a rectifying tower for separating ethanol, a rectifying tower for separating cyclohexanol and a rectifying tower for separating cyclohexyl acetate, an ester hydrogenation product firstly enters the gas-liquid separation tank to separate hydrogen, then sequentially enters an ethanol removal tower to separate ethanol, then enters a cyclohexanol removal tower to separate cyclohexanol, and finally enters a cyclohexyl acetate recovery tower to recover unreacted cyclohexyl acetate for recycling, and a small amount of high-boiling residues remained in a tower kettle are sent out of the system.

The invention also provides a device for coproducing cyclohexanol and ethanol, which is characterized by comprising an acid alkene esterification reaction unit, an alkyd esterification reaction unit, a cyclohexyl acetate purification unit, a cyclohexyl acetate hydrogenation unit and an ester hydrogenation product separation unit;

According to the device, the alkyd esterification reaction unit at least comprises a catalytic rectifying tower or an extraction catalytic rectifying tower.

The apparatus according to the present invention further comprises a unit for producing benzene from the dehydrogenation of the cyclohexane having a purity of greater than 95% and producing the cyclohexene feed from the benzene.

The invention is further illustrated by the following examples, which are not intended to be limiting.

The tests of examples 1 and 2 were carried out in a pilot plant constructed as shown in FIG. 2. The method comprises the steps of carrying out esterification reaction on acid and olefin in a fixed bed reactor and a catalytic rectifying tower, carrying out esterification reaction on the acid and the olefin in the catalytic rectifying tower, purifying cyclohexyl acetate in a deacidification rectifying tower and a heavy component removal rectifying tower, carrying out ester hydrogenation reaction in a tubular fixed bed reactor, and separating ester hydrogenation products in an ethanol rectifying tower and a cyclohexanol rectifying tower. The specifications of each main apparatus are shown in Table 1.

Table 1 main equipment of pilot plant constructed according to fig. 2

The strongly acidic resin catalysts of Table 1 were synthesized according to the classical literature procedure by suspension copolymerization of a styrene solution containing 15 m% divinylbenzene to form white spheres, which were sulfonated with concentrated sulfuric acid and had an exchange capacity of 5.2mmol H⁺On a dry basis per gram.

The copper-based ester hydrogenation catalyst comprises the following components: 40.5 m% of CuO, 29.6 m% of ZnO and Al₂O₃30.4 m%. The synthesis method comprises the following steps: prepared by adding sodium hydroxide solution into nitrate solution of copper, zinc and aluminum to neutralize until the pH is 9.0, centrifugally separating, washing, drying, tabletting, molding and roasting, and is loaded into a stainless steel tube reactor with a jacket (the external diameter of the jacket is shown in Table 1) with the diameter of 20mm multiplied by 2.5mm multiplied by 800 mm.

Example 1

This example was carried out in a pilot plant as shown in FIG. 2, with a molar ratio of acetic acid to cyclohexene in the feed to reactor R-101 of 1.37: 1. The operating conditions and test results of the main equipment of each unit are shown in tables 2 and 3.

Table 2 operating conditions and test results of the main equipment of each unit in example 1

Table 3 main logistics table of example 1

Note: the cyclohexene raw material feed and the acetic acid feed are the raw material feeds in the step (1); recycling cyclohexanol as the cyclohexanol feed of step (2); the byproduct cyclohexane product is the top product of the step (2); the intermediate product, cyclohexyl acetate, is the ester product of step (3).

Example 2

This example was carried out in a pilot plant as shown in FIG. 2, with a molar ratio of acetic acid to cyclohexene in the feed to reactor R-101 of 1.8: 1. The operating conditions and test results of the main equipment of each unit are shown in tables 4 and 5.

Table 4 operating conditions and test results of the main equipment of each unit in example 2

Table 5 main logistics table of example 2

The test of example 3 was carried out in a catalytic rectification mode test apparatus constructed as shown in FIG. 3. The main body of the mode device consists of three titanium stainless steel tower sections with the diameter (inner diameter) of 50mm and the height of 1 m; wherein, the 1 st section and the 3 rd section are respectively a rectifying section and a stripping section, the phi 3 theta net ring packing is filled in the section, and the number of each section of theoretical plate is 30; the middle section is provided with a rectification component containing catalystThe manufacturing method of the part comprises the following steps: catalyst particles are filled into small bags made of titanium wire mesh, the small bags filled with the catalyst are clamped between wire mesh corrugated packings to prepare phi 49.5mm multiplied by 50mm regular packings, and finally the regular packings are filled into a middle reaction tower section in a vertically staggered angle of 90 degrees, the volume fraction of the catalyst in the regular packings is 35 percent, and the theoretical plate number of the middle section is 32. The lower part of the tower is connected with a tower kettle with the volume of 5L, an electric heating rod with 10KW is arranged in the kettle, and the heating rod controls the heating quantity of the tower kettle through a Silicon Controlled Rectifier (SCR) by an intelligent controller. The tower top is connected with a heat exchange area of 0.5m²The overhead vapor is condensed into liquid by the condenser and then enters a reflux tank with the volume of 2L. One part of cyclohexane obtained by phase separation in the reflux tank flows back to the catalytic rectifying tower through a reflux pump, and the other part is extracted. The operating parameters of the tower are displayed and controlled by an intelligent automatic control instrument. The tower reflux amount is controlled by a reflux regulating valve, and the tower top extraction amount is controlled by a liquid level controller of a reflux tank. The extraction amount of the tower kettle is controlled by adjusting a discharge valve of the tower kettle by a liquid level controller of the tower kettle. Alcohol and cyclohexane raw materials are respectively put into a 30L storage tank, and are pumped into a corresponding preheater through a metering pump to be preheated to a certain temperature, the alcohol enters a catalytic rectification tower from the upper end of a reaction section, the cyclohexane raw materials enter the catalytic rectification tower from the lower end of the reaction section, and the feeding speeds of the alcohol and the cyclohexane raw materials are respectively controlled by the metering pump and accurately metered by an electronic scale.

Example 3

This example is intended to illustrate the effects of the implementation when cyclohexanol is used.

The test was carried out in a molding apparatus shown in FIG. 3. The catalyst loaded in the reaction section is high-temperature resistant sulfonic acid type ion exchange resin (synthesized by the conventional technology in the laboratory, styrene and divinyl benzene are suspended and copolymerized into white balls, and SO is further used for preparing the white balls₃Obtained by sulfonation, having an exchange capacity of 5.4mmolH⁺Per gram of dry agent). The cyclohexanol and cyclohexane material are pumped separately into preheater via metering pump and preheated before entering the catalytic rectifying tower, and the amount of heated material in the tower and the amount of reflux in the tower top are regulated for continuous reaction, with the reaction conditions and results being shown in Table 6.

Table 6 reaction conditions and reaction results of example 3

The test in example 4 was carried out in an extractive catalytic rectification mode test unit as shown in FIG. 4. The main body of the model device is composed of four sections of titanium stainless steel sections with the diameter (inner diameter) of 50mm and the height of 1m, wherein the 1 st section, the 2 nd section and the 4 th section are respectively a rectifying section, an extracting section and a stripping section, phi 3 titanium theta mesh ring packing is filled in the titanium stainless steel sections, and the number of theoretical plates of each section is 20. Section 3 is a reaction section, in which a rectification member containing a catalyst is installed, and the manufacturing method of the member is as follows: catalyst particles are filled into small bags made of titanium wire meshes, the small bags filled with the catalyst are clamped between wire mesh corrugated packings to prepare phi 49.5mm multiplied by 50mm regular packings, and finally the regular packings are filled into a reaction tower section in a vertically staggered 90-degree angle mode, the volume fraction of the catalyst in the regular packings is 35%, and the theoretical plate number of a reaction section is 15. The lower part of the tower is connected with a tower kettle with the volume of 5L, an electric heating rod with 10KW is arranged in the kettle, and the heating rod controls the heating quantity of the tower kettle through a Silicon Controlled Rectifier (SCR) by an intelligent controller. The tower top is connected with a heat exchange area of 0.5m²The overhead vapor is condensed into liquid by the condenser and then enters a reflux tank with the volume of 2L. One part of the liquid (cyclohexane) in the reflux tank flows back to the extraction catalytic rectification tower through a reflux pump, and the other part is extracted. The operating parameters of the tower are displayed and controlled by an intelligent automatic control instrument. The tower reflux amount is controlled by a reflux regulating valve, and the tower top extraction amount is controlled by a liquid level controller of a reflux tank. The extraction amount of the tower kettle is controlled by adjusting a discharge valve of the tower kettle by a liquid level controller of the tower kettle. The alcohol and cyclohexane are filled into 30L storage tanks, and are pumped into corresponding preheaters through metering pumps to be preheated to a certain temperature and then enter an extraction catalytic distillation tower, the feeding speed metering pump is controlled, and the electronic scale is used for accurate metering.

Example 4

This example illustrates the effect of a test using cyclohexanol as the extractant and esterification agent.

The test was carried out in a molding apparatus shown in FIG. 4. In the reaction sectionThe catalyst is high-temperature resistant sulfonic acid ion exchange resin (synthesized by conventional technique in laboratory, styrene and divinyl benzene are suspended and copolymerized into white balls, and SO is used₃Obtained by sulfonation, having an exchange capacity of 5.4mmolH⁺Per gram of dry agent). The cyclohexanol and cyclohexane material are pumped separately into preheater via metering pump and preheated before entering the extracting, catalyzing and rectifying tower, and the reaction conditions and results in stable operation are shown in Table 7.

Table 7 reaction conditions and reaction results of example 4

Claims

(2) removing acetic acid in a cyclohexane raw material by using cyclohexanol through catalytic distillation to obtain cyclohexane with the purity of more than 95 percent, and simultaneously manufacturing cyclohexyl acetate; the cyclohexane feed consists of cyclohexane, acetic acid and optionally benzene and/or cyclohexene; the purity of the cyclohexane is calculated by the total mass fraction of benzene, cyclohexene and cyclohexane; in the cyclohexane raw material, the mass fraction of acetic acid is 10-35%;

(3) a step of purifying cyclohexyl acetate;

(5) a step of purifying cyclohexanol and ethanol;

wherein the steps (1) to (5) are carried out in the manner A or the manner B,

mode A:

mode B:

wherein step (2) is carried out in the manner (I) or the manner (II),

mode (II): the method is carried out in an extractive catalytic distillation tower, and the tower comprises a distillation section, an extraction section, a reaction section and a stripping section from top to bottom; a cyclohexane raw material enters from the upper part of the extraction section and is in countercurrent contact with cyclohexanol entering from the lower part of the reaction section, so that acetic acid and cyclohexanol in the cyclohexane raw material are subjected to esterification reaction and removed, and cyclohexane with the purity of more than 95% is obtained from the top of the tower;

in the modes (I) and (II), the adopted esterification catalyst is strong-acid ion exchange resin.

2. The method according to claim 1, wherein the mass fraction of acetic acid in the cyclohexane feed is 10% to 20%.

3. A process according to claim 1, wherein the cyclohexane feed is an azeotrope of cyclohexane and acetic acid or an azeotrope of cyclohexane, acetic acid and cyclohexene and/or benzene.

4. The process according to claim 1, wherein the cyclohexane feed has a mass fraction of benzene of 0.2% to 1% and a mass fraction of cyclohexene of 0.5% to 2%.

5. The method according to claim 1, wherein in the mode (I), the number of theoretical plates of the catalytic distillation column is 10 to 150, and the catalyst is arranged between 1/3 and 2/3 theoretical plates.

6. The process according to claim 5, wherein in the mode (I), the molar ratio of the feeding amount of the alcohol to the feeding amount of the acetic acid in the cyclohexane raw material is 1.01:1 to 1.1: 1.

7. The method according to claim 1, wherein in the mode (II), in the extractive catalytic distillation column, the number of theoretical plates in the distillation section is 10 to 50, the number of theoretical plates in the extraction section is 10 to 50, the number of theoretical plates in the reaction section is 10 to 50, and the number of theoretical plates in the stripping section is 10 to 50.

8. The process according to claim 7, wherein in the mode (II), the molar ratio of the feeding amount of the alcohol to the feeding amount of the acetic acid in the cyclohexane raw material to be separated is 1:1 to 1.1: 1.

9. The process according to claim 1, wherein in the modes (I) and (II), the reflux ratio is 0.5:1 to 3: 1.

10. The process according to claim 1, wherein in modes (i) and (ii), the operating conditions are: the operating pressure is-0.0099 MPa to 5.0MPa, the temperature of a catalyst bed is 50 ℃ to 200 ℃, and the feeding space velocity of acetic acid to the total loading amount of the catalyst is 0.2h < -1 > to 20h < -1 >.

11. The process according to claim 1, wherein in the modes (I) and (II), the cyclohexane obtained from the top of the column has an acetic acid content of less than 50ppm by mass.

12. The process according to claim 1, wherein in modes (I) and (II), the acetic ester having a purity of more than 90% is obtained from the bottom of the column in terms of mass fraction.

13. The process of claim 1, wherein said cyclohexane having a purity greater than 95% is used in a dehydrogenation reaction to produce benzene, and said benzene is used in the production of said cyclohexene feedstock.

14. An apparatus for carrying out the method of claim 1, comprising an acid alkene esterification reaction unit, an alkyd esterification reaction unit, a cyclohexyl acetate purification unit, a cyclohexyl acetate hydrogenation unit, and an ester hydrogenation product separation unit;

the alcohol acid esterification reaction unit is used for reacting cyclohexanol with cyclohexane raw material, removing acetic acid in the cyclohexane raw material, obtaining cyclohexane with purity of more than 95%, and simultaneously preparing cyclohexyl acetate; the alkyd esterification reaction unit at least comprises a catalytic rectifying tower or an extraction catalytic rectifying tower;

15. The apparatus of claim 14, further comprising a unit for dehydrogenating said cyclohexane having a purity greater than 95% to produce benzene and producing said cyclohexene feed from said benzene.