CN116020143A - Device and method for preparing cyclohexanone by cyclohexanol dehydrogenation - Google Patents
Device and method for preparing cyclohexanone by cyclohexanol dehydrogenation Download PDFInfo
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- CN116020143A CN116020143A CN202111246478.9A CN202111246478A CN116020143A CN 116020143 A CN116020143 A CN 116020143A CN 202111246478 A CN202111246478 A CN 202111246478A CN 116020143 A CN116020143 A CN 116020143A
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Abstract
The invention provides a device and a method for preparing cyclohexanone by cyclohexanol dehydrogenation, wherein the device comprises the following steps: an atmospheric tower for reducing the content of intermediate accumulated impurities in the cyclohexanol material; the tower bottom of the atmospheric tower is provided with an intermediate accumulated impurity outlet for discharging cyclohexanol liquid containing intermediate accumulated impurities; a dehydrogenation reaction unit for performing cyclohexanol dehydrogenation reaction; the light tower is used for separating light impurities in the alcohol-ketone mixture material; a ketone column for refining the alcohol ketone liquid phase; and the alcohol tower is used for removing heavy impurities of the crude cyclohexanol materials. By arranging the atmospheric tower, before the cyclohexanol material enters the dehydrogenation reaction unit, the intermediate accumulated impurities are removed in advance, so that accumulation is avoided, and other impurities generated in the dehydrogenation reaction process by the intermediate accumulated impurities are reduced; the intermittent extracted circulation cyclohexanol is returned to the atmospheric tower, intermediate accumulated impurities are removed, the intermittent extracted circulation cyclohexanol can be controlled to an ideal level without accumulating to a certain content, stable operation of the device is not affected, and stable operation of the device is facilitated.
Description
Technical Field
The invention relates to the technical field of cyclohexanone preparation, in particular to a device and a method for preparing cyclohexanone by cyclohexanol dehydrogenation.
Background
The cyclohexanone is mainly applied to industries such as fiber, rubber, medicine, organic solvent and the like, and is an important chemical intermediate raw material for producing products such as caprolactam, adipic acid, nylon 66 and the like. The production and preparation of the cyclohexanol are generally realized by gas-phase catalytic dehydrogenation of the cyclohexanol in the industry, the once-through conversion rate of the cyclohexanol is generally 50-60%, and impurities are generated by side reactions. Thus, in existing cyclohexanone preparation processes, a separation scheme of the mixture of alcohols and ketones with other impurities must be included. Because the boiling point of the alcohol ketone is close to that of the alcohol ketone, and the boiling point of the alcohol ketone is higher under normal pressure, the industrial alcohol ketone separation process is generally realized by reduced pressure rectification.
The traditional process is roughly divided into three steps: "light removal+refined ketone+heavy removal". The light component removal step is to separate light impurities in the crude alcohol ketone mixture through the light component removal tower by vacuum distillation, and to reduce the ketone content in the light oil and improve the recovery rate of cyclohexanone, the reflux ratio of the light component removal tower is usually controlled to be very high, or a light two-tower is added to carry out secondary distillation to recover the cyclohexanone in the externally thrown light oil; "refined ketone": the refined ketone product is obtained through the reduced pressure rectification of the ketone tower, so that the number of theoretical plates required by the ketone tower is more, and the separation efficiency is low; the heavy impurities in the cyclohexanol are separated through the alcohol tower under reduced pressure, so that the influence of more heavy impurities in the circulating cyclohexanol on the dehydrogenation reaction is avoided. The alcohol ketone separation process is realized by at least 3-4 vacuum rectification systems, a large amount of energy is consumed, equipment investment is high, wherein the energy consumption of light component removal is about 40-60% of the total energy consumption of alcohol ketone separation, and the energy consumption of refined ketone and heavy component removal is about one level.
In addition, since the whole separation process is a depressurization operation, components having boiling points close to that of cyclohexanol under reduced pressure cannot be effectively separated, and accumulation of impurities in the cyclohexanol raw material may be caused.
CN106518640a discloses a method for efficiently separating and refining cyclohexanone product, which utilizes a single cyclohexanone column to remove light components and simultaneously refine cyclohexanone. However, this invention does not provide a good solution to the intermediate accumulation of impurities which cannot be separated from cyclohexanol during the depressurization operation.
CA106083544A discloses a method and a system for preparing cyclohexanone by cyclohexanol dehydrogenation, wherein alcohol-ketone mixture is separated by a dehydrogenation tower, a cyclohexanone product tower and a cyclohexanol recovery tower, light components are removed from the alcohol-ketone mixture to obtain a cyclohexanone product, cyclohexanol at the top of the cyclohexanol recovery tower enters a dehydrogenation reactor for dehydrogenation reaction to obtain an alcohol-ketone mixture, and the alcohol-ketone mixture passes through the dehydration tower, a cyclohexane extraction tower and the alcohol-ketone recovery tower to improve the recovery rate of alcohol ketone. Although the invention obtains the cyclohexanone product with high purity, improves the utilization rate of cyclohexanol, and reduces energy consumption by adopting a heat coupling mode; however, once the content of intermediate accumulated impurities increases, the dehydration tower and the alcohol ketone recovery tower operated at normal pressure cannot realize the removal thereof, and tend to cause the accumulation thereof in the reaction circulation system.
CN111662171a discloses a method for removing cyclohexanone and intermediate components in cyclohexanol, separating crude alcohol in the kettle of a ketone tower by using a partition tower, returning cyclohexanol with cyclohexanone in the top of the tower to a crude alcohol ketone tank, discharging kettle liquid, and returning a side line to the crude alcohol tank; and the separation of the intermediate components is completed by means of decompression and normal pressure rectification. However, when the content of the intermediate component in the crude alcohol tank is not high, the intermediate component is difficult to separate in the two ways, and the economic benefit brought by the method is considerable only when the content of the intermediate component in the system is accumulated to a certain extent, and the continuous operation can add extra energy consumption to the production process of the device.
According to the analysis, aiming at the alcohol-ketone separation process, the energy consumption of the light-removal step is maximum, but the energy consumption can be obviously reduced by a few methods; although many solutions have been proposed in recent years for accumulation of intermediate accumulated impurities in recycle cyclohexanol, good separation effect can be achieved only when intermediate accumulated impurities accumulate to a certain level in the system by intermittent operation, it is difficult to control it at a low level, and stable operation of the apparatus is not favored.
Disclosure of Invention
The invention aims to provide a device and a method for preparing cyclohexanone by dehydrogenating cyclohexanol, which can greatly reduce the energy consumption of the device and control the content of accumulated impurities in the middle to be at a lower level, and are beneficial to the stable operation of the device.
In order to achieve the above object, the present invention provides an apparatus for preparing cyclohexanone by dehydrogenating cyclohexanol, comprising:
an atmospheric tower for reducing the content of intermediate accumulated impurities in the cyclohexanol material; the normal pressure tower is provided with a cyclohexanol raw material inlet; the top of the atmospheric tower is provided with a cyclohexanol material outlet for discharging cyclohexanol materials; the tower bottom of the atmospheric tower is provided with an intermediate accumulated impurity outlet for discharging cyclohexanol liquid containing intermediate accumulated impurities;
a dehydrogenation reaction unit for performing cyclohexanol dehydrogenation reaction; the dehydrogenation reaction unit is provided with a cyclohexanol material inlet and an alcohol ketone product material outlet; the cyclohexanol material inlet is communicated with a cyclohexanol material outlet of the atmospheric tower and is used for enabling the cyclohexanol material to enter the dehydrogenation reaction unit; the alcohol ketone product material outlet is used for discharging alcohol ketone mixture materials;
a light column for separating light impurities in the alcohol ketone mixture material; the light tower is provided with an alcohol-ketone mixture material inlet which is communicated with an alcohol-ketone product material outlet of the dehydrogenation reaction unit and is used for enabling the alcohol-ketone mixture material to enter the light tower; the top of the light tower is provided with a light impurity outlet for discharging light impurities in the alcohol-ketone mixture material; the light tower kettle is provided with an alcohol ketone liquid phase outlet for discharging an alcohol ketone liquid phase;
a ketone column for refining the alcohol ketone liquid phase; the ketone tower is provided with an alcohol ketone liquid phase inlet which is communicated with an alcohol ketone liquid phase outlet of the light tower and is used for enabling the alcohol ketone liquid phase to enter the ketone tower; the top of the ketone tower is provided with a cyclohexanone product outlet for extracting cyclohexanone products; the ketone tower kettle is provided with a crude cyclohexanol material outlet for discharging crude cyclohexanol material;
an alcohol tower for removing heavy impurities from the crude cyclohexanol material; the alcohol tower is provided with a crude cyclohexanol material inlet which is communicated with a crude cyclohexanol material outlet of the ketone tower and is used for enabling the crude cyclohexanol material to enter the alcohol tower; the top of the alcohol tower is provided with a circulating cyclohexanol material outlet which is communicated with one feed inlet of the dehydrogenation reaction unit and/or one feed inlet of the normal pressure tower.
An apparatus for the dehydrogenation of cyclohexanol to cyclohexanone as described above, wherein the apparatus further comprises an atmospheric tower condenser for heat exchanging cyclohexanol material from the atmospheric tower with an alcohol ketone liquid phase from the light tower kettle or crude cyclohexanol material from the ketone tower kettle or kettle material from the alcohol tower kettle in the atmospheric tower condenser.
The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol as described above, wherein the cold-hot side temperature difference of the atmospheric tower condenser is not less than 10 ℃.
The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol as described above, wherein the content of intermediate accumulated impurities in the cyclohexanol material entering the dehydrogenation reaction unit is not higher than 50ppm based on the total weight of the cyclohexanol material.
The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol as described above, wherein the overhead operating pressure of the light column is 20-90kPa.
The apparatus for producing cyclohexanone by dehydrogenation of cyclohexanol as described above, wherein the operation pressure of the ketone column and the alcohol column is in the range of 0.5 to 50kPa.
The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol as described above, wherein the operating pressure of the atmospheric tower is 101-350kPa.
The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol as described above, wherein the intermediate accumulated impurity is a substance having a boiling point close to that of cyclohexanol under vacuum conditions but a boiling point higher than that of cyclohexanol under normal pressure or pressure conditions; the light impurity is a substance with a boiling point lower than or close to that of cyclohexanone under vacuum condition; the heavy impurities are substances with boiling points higher than the boiling point of cyclohexanol under vacuum conditions.
The embodiment of the invention also provides a method for preparing cyclohexanone by cyclohexanol dehydrogenation, which is performed in the device for preparing cyclohexanone by cyclohexanol dehydrogenation, and comprises the following steps:
introducing cyclohexanol raw material into an atmospheric tower from a cyclohexanol raw material inlet for atmospheric distillation, discharging cyclohexanol liquid containing intermediate accumulated impurities from the bottom of the atmospheric tower through an intermediate accumulated impurity outlet, and discharging cyclohexanol material from the top of the atmospheric tower through a cyclohexanol material outlet;
enabling the cyclohexanol material to enter a dehydrogenation reaction unit through a cyclohexanol feed inlet of the dehydrogenation reaction unit, and carrying out dehydrogenation reaction in the dehydrogenation reaction unit to obtain an alcohol ketone product material;
enabling the alcohol ketone product material to enter a light tower through an alcohol ketone product material inlet of the light tower, removing light impurities and water in the alcohol ketone product material, and discharging an alcohol ketone liquid phase through an alcohol ketone liquid phase outlet of the light tower;
enabling the alcohol ketone liquid phase to enter a ketone tower through an alcohol ketone liquid phase inlet for refining, obtaining a cyclohexanone product at the top of the ketone tower, and extracting from a cyclohexanone product outlet; the crude cyclohexanol material is discharged via a crude cyclohexanol material outlet;
the crude cyclohexanol material enters the alcohol tower through a crude cyclohexanol material inlet to remove heavy impurities in the crude cyclohexanol; the recycle cyclohexanol material is discharged via a recycle cyclohexanol material outlet, which communicates with one feed inlet of the dehydrogenation reaction unit and/or one feed inlet of the atmospheric tower, such that the recycle cyclohexanol material is returned to the dehydrogenation reaction unit and/or the atmospheric tower.
The method for preparing cyclohexanone by cyclohexanol dehydrogenation, which comprises the steps of carrying out heat exchange between cyclohexanol materials from an atmospheric tower and alcohol ketone liquid phase from a light tower kettle or crude cyclohexanol materials from a ketone tower kettle or tower kettle materials from the alcohol tower kettle in the atmospheric tower condenser;
preferably, the cyclohexanol feed from the atmospheric tower is heat exchanged with the alcohol ketone liquid phase from the light ends tower.
The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol as described above, wherein the operating pressure of the atmospheric tower is 101-350kPa;
the top operating pressure of the light column is 20-90kPa;
the ketone column and the alcohol column are operated at a pressure of from 0.5 to 50kPa.
Compared with the prior art, the technical scheme has the following advantages: by arranging the atmospheric tower, before cyclohexanol materials enter the dehydrogenation reaction unit, intermediate accumulated impurities are removed in advance, so that accumulation of the intermediate accumulated impurities in the whole reaction circulation system is avoided, and other impurities generated in the dehydrogenation reaction process by the intermediate accumulated impurities are reduced; the circulation cyclohexanol material outlet of the alcohol tower is connected with one feed inlet of the normal pressure tower, so that the extracted circulation cyclohexanol material can be returned to the normal pressure tower, intermediate accumulated impurities in the circulation cyclohexanol can be removed, the intermediate accumulated impurities are not required to be accumulated to a certain content, and the circulation cyclohexanol material can be controlled to an ideal level, so that stable operation of the device is not influenced, and stable operation of the device is facilitated; through setting up the condenser at the top of the atmospheric tower, accomplish the heat transfer of the overhead cyclohexanol steam of atmospheric tower and light tower cauldron alcohol ketone product for the coupling of ordinary pressure-decompression rectification heat has realized the heat and has utilized, reduces the device energy consumption.
Drawings
The following drawings are only for purposes of illustration and explanation of the present invention and are not intended to limit the scope of the invention. Wherein:
FIG. 1 is a schematic flow chart of an apparatus and process for producing cyclohexanone by dehydrogenation of cyclohexanol according to the present invention;
fig. 2 is a process flow diagram for preparing cyclohexanone in the comparative example of the present invention.
Detailed Description
The present application is further described in detail below by way of the accompanying drawings and examples. The features and advantages of the present application will become more apparent from the description.
The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.
As shown in fig. 1, the apparatus for producing cyclohexanone by dehydrogenation of cyclohexanol provided herein comprises an atmospheric tower 1, wherein the atmospheric tower 1 is used for reducing the content of intermediate accumulated impurities in cyclohexanol material. Specifically, the atmospheric tower 1 is provided with a cyclohexanol feedstock inlet, via which cyclohexanol feedstock 101 enters the atmospheric tower 1. The top of the atmospheric tower 1 is provided with a cyclohexanol material outlet for discharging cyclohexanol material 102, in which case the discharged cyclohexanol material 102 is in the gas phase, and in one embodiment the cyclohexanol material outlet is connected via a line to the atmospheric tower condenser 2, as will be described later. After the cyclohexanol material 102 in a gas phase state flows through the atmospheric tower condenser 2, heat is released to obtain a liquid cyclohexanol material 103, the liquid cyclohexanol material 103 flows into the atmospheric tower reflux tank 3 through a pipeline, and a part of cyclohexanol material returns to the atmospheric tower 1 as reflux 104 for reuse; and the other part of the raw material is taken as a cyclohexanol material 105 to enter a dehydrogenation reaction unit for reaction through a cyclohexanol material feed inlet of the dehydrogenation reaction unit so as to prepare cyclohexanone. The tower bottom of the atmospheric tower 1 is provided with an intermediate accumulated impurity outlet for discharging cyclohexanol liquid containing intermediate accumulated impurities, specifically, after the tower bottom reactant 106 is heated by the atmospheric tower kettle reboiler 4, one part of the cyclohexanol liquid is refluxed to the atmospheric tower 1 for reuse, and the other part of cyclohexanol liquid 107 rich in intermediate accumulated impurities is discharged, so that the content of intermediate accumulated impurities in cyclohexanol materials entering the dehydrogenation reaction unit is reduced. In a specific embodiment, the content of intermediate accumulated impurities in the cyclohexanol feed to the dehydrogenation reaction unit is no more than 50ppm, based on total weight of cyclohexanol feed.
In one embodiment, the operating pressure of the atmospheric tower is 101-350kPa, the overhead temperature is 160-220 ℃, and the reflux ratio is 1.0-30: 1.
after cyclohexanol feed 105 enters the dehydrogenation unit, cyclohexanol feed 105 may be dehydrogenated in the presence of a catalyst to yield alcohol ketone mixture 120. The cyclohexanol feed to the dehydrogenation reaction unit may be cyclohexanol feed 105 after removal of intermediate accumulated impurities by atmospheric tower 1, and may also comprise a quantity of recycle alcohol feed 136, as described below. The hydrogen 119 generated by the dehydrogenation reaction unit is discharged through a pipeline, and the obtained alcohol ketone mixture material 120 is discharged through an alcohol ketone product material outlet and then enters a subsequent light tower 12 for separation treatment.
The dehydrogenation reaction unit and the dehydrogenation reactions occurring therein can employ reactors and reaction conditions known in the art. For example, the temperature may be 220 to 280℃and the pressure 2 to 30kPa. The catalyst used may also be various catalysts known in the art and will not be described in detail herein.
The apparatus of the present application comprises a light column 12 for separating light impurities in an alcohol ketone mixture stream 120, comprising: light impurities 124 and water 117 to yield an ethanolone liquid phase 126. Alcohol ketone mixture 120 enters the light column 12 from the middle part, a light column top material 121 can be in a gas phase, flows through the light column top condenser 13 and then is condensed into a liquid phase material 122, enters the light column top reflux tank 14, light impurities 124 and water 117 obtained through separation are discharged, and the rest material flow 123 flows back to the top of the light column 12. In one embodiment, the light column has a top operating pressure of 20-90kPa, a top temperature of 85-120 ℃, and a top reflux ratio of 50-900: 1.
in the embodiment shown in fig. 1, a portion of the alcohol ketone liquid phase 125 at the bottom of the light column 12 flows through the atmospheric column condenser 2, exchanges heat with the cyclohexanol feed 102 from the atmospheric column in the atmospheric column condenser 2, gasifies back to the light column 12, and another portion of the alcohol ketone liquid phase 126 enters the ketone column 16. In one embodiment, the temperature of the tower kettle is 110-160 ℃, and the reflux ratio of the tower kettle is 0.80-15: 1.
the apparatus of the present application includes a ketone column 16 for refining an alcohol ketone liquid phase 126 to yield a qualified ketone product 130 and a crude cyclohexanol 132 comprising a portion of cyclohexanone. The alcohol ketone liquid phase 126 enters the ketone column 16, a liquid phase stream 128 of the ketone column top gas phase material 127 cooled by the ketone column top condenser 17 enters the ketone column top reflux drum 18 through a pipeline, a part of the liquid phase stream 129 returns to the ketone column 16 as reflux, and the other part is extracted as qualified ketone product 130. And the tower kettle material 131 of the ketone tower kettle is heated by the ketone tower kettle reboiler 19, a part of tower kettle material 131 is reboiled and then flows back into the ketone tower 16, and the other part of crude cyclohexanol 132 containing part of cyclohexanone is discharged and then enters the alcohol tower 20 so as to remove heavy impurities in the crude cyclohexanol. In one embodiment, the overhead temperature is 101 to 150 ℃, and the overhead reflux ratio is 1 to 5:1, the temperature of the tower kettle is 116-160 ℃, and the reflux ratio of the tower kettle is 2-8: 1.
the apparatus of the present application includes an alcohol column 20 for removing heavy impurities from the crude cyclohexanol material to provide recycled cyclohexanol, which is returned to the dehydrogenation reaction unit and/or to the atmospheric column for reuse. The gas phase material 133 at the top of the alcohol tower enters the condenser 21 at the top of the alcohol tower, the condensed liquid phase flow 134 enters the reflux tank 22 at the top of the alcohol tower, a part of the material 135 returns to the alcohol tower 20 as reflux, the other part of the material is extracted as recycle cyclohexanol 136, and a part of the material returns to the dehydrogenation reaction unit for further reaction; the other part of the recycle cyclohexanol 108 is returned to the atmospheric tower 1, and the intermediate accumulated impurities accumulated in the recycle cyclohexanol are separated and then enter a dehydrogenation reaction unit to continue the reaction. The total ratio of the circulating cyclohexanol material entering the normal pressure tower to the circulating cyclohexanol extracted from the top of the alcohol tower can be regulated as required, for example, the ratio is less than or equal to 40%.
After the alcohol column bottoms 137 is heated by the alcohol column bottoms reboiler 23, a portion of the bottoms 137 is reboiled back to the alcohol column 20 and the heavy impurities 138 are vented. In one embodiment, the overhead temperature is 47-140 ℃, and the overhead reflux ratio is 0.5-3: 1, the temperature of the tower kettle is 90-230 ℃, and the reflux ratio of the tower kettle is 20-800: 1.
in this application, the ketone column 16 and alcohol column 20 may be operated at pressures of from 0.5 to 50kPa.
In a specific embodiment, the device for preparing cyclohexanone by dehydrogenating cyclohexanol comprises an atmospheric tower condenser 2, and the device is used for exchanging heat between cyclohexanol materials from the atmospheric tower 1 and alcohol ketone liquid phase from a light tower kettle or crude cyclohexanol materials from a ketone tower kettle or tower kettle materials from the alcohol tower kettle in the atmospheric tower condenser 2. In one embodiment, the apparatus for dehydrogenating cyclohexanol to produce cyclohexanone comprises an atmospheric tower condenser 2 for heat exchanging cyclohexanol material from the atmospheric tower 1 with an alcohol ketone liquid phase from the light tower kettle.
In an alternative embodiment, the apparatus for dehydrogenating cyclohexanol to produce cyclohexanone comprises an atmospheric tower condenser 2 for heat exchanging cyclohexanol material from the atmospheric tower 1 with crude cyclohexanol material from the ketone tower kettle or with kettle material from the alcohol tower kettle in the atmospheric tower condenser 2, i.e. ketone tower kettle reboiler 19 and alcohol tower kettle reboiler 23 may each be replaced with the atmospheric tower condenser 2. In one embodiment, the cold-hot side temperature difference of the atmospheric tower condenser 2 is no less than 10 degrees celsius.
Thus, the present application provides a method for producing cyclohexanone by dehydrogenation of cyclohexanol, which can be performed in the device for producing cyclohexanone by dehydrogenation of cyclohexanol, and comprises the following steps:
introducing cyclohexanol raw material into an atmospheric tower from a cyclohexanol raw material inlet for atmospheric distillation, discharging cyclohexanol liquid containing intermediate accumulated impurities from the bottom of the atmospheric tower through an intermediate accumulated impurity outlet, and discharging cyclohexanol material from the top of the atmospheric tower through a cyclohexanol material outlet;
enabling the cyclohexanol material to enter a dehydrogenation reaction unit through a cyclohexanol feed inlet of the dehydrogenation reaction unit, and carrying out dehydrogenation reaction in the dehydrogenation reaction unit to obtain an alcohol ketone product material;
enabling the alcohol ketone product material to enter a light tower through an alcohol ketone product material inlet of the light tower, removing light impurities and water in the alcohol ketone product material, and discharging an alcohol ketone liquid phase through an alcohol ketone liquid phase outlet of the light tower;
enabling the alcohol ketone liquid phase to enter a ketone tower through an alcohol ketone liquid phase inlet for refining, obtaining a cyclohexanone product at the top of the ketone tower, and extracting from a cyclohexanone product outlet; the crude cyclohexanol material is discharged via a crude cyclohexanol material outlet;
the crude cyclohexanol material enters the alcohol tower through a crude cyclohexanol material inlet to remove heavy impurities in the crude cyclohexanol; the recycle cyclohexanol material is discharged via a recycle cyclohexanol material outlet, which communicates with one feed inlet of the dehydrogenation reaction unit and/or one feed inlet of the atmospheric tower, such that the recycle cyclohexanol material is returned to the dehydrogenation reaction unit and/or the atmospheric tower.
It should be noted that the description of the related embodiments of the apparatus is equally applicable to the method, and will not be repeated here.
In one embodiment, the method of the present application further comprises: heat exchanging cyclohexanol material from an atmospheric tower with alcohol ketone liquid phase from a light tower kettle or crude cyclohexanol material from a ketone tower kettle or tower kettle material from the alcohol tower kettle in the atmospheric tower condenser;
preferably, the cyclohexanol feed from the atmospheric tower is heat exchanged with the alcohol ketone liquid phase from the light ends tower.
In one embodiment, the atmospheric tower operates at a pressure of 101 to 350kPa;
the top operating pressure of the light column is 20-90kPa;
the ketone column and the alcohol column are operated at a pressure of from 0.5 to 50kPa.
In the present application, the intermediate accumulated impurities refer to substances having a boiling point close to (within ±10 ℃ from) the boiling point of cyclohexanol under vacuum conditions (1 to 90 kPa), but a boiling point higher than that of cyclohexanol under normal pressure or pressurized conditions, including but not limited to: ethylcyclohexanone, cyclohexylketone, cyclohexyl acetate, and the like.
In the present application, light impurities refer to substances having a boiling point lower than that of cyclohexanone under vacuum conditions (1 to 90 kPa), including but not limited to: water, alcohols such as ethanol, propanol, n-isobutanol, n-iso-neopentyl alcohol and cyclopentanol, aldehydes such as acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde and cycloalkylaldehyde, ketones such as acetone, butanone, pentanone, alkyl cyclopentanone and cycloalkyl ketone, cyclohexyl ethers such as methyl cyclohexyl ether, ethyl cyclohexyl ether and butyl cyclohexyl ether, olefins such as ethylene, propylene, butene, cyclohexene and cyclopentene, esters such as ethyl acetate and butyl acetate, ketenes such as cyclopentenone and cyclohexenone, epoxy groups such as ethylene oxide, propylene oxide and epoxycyclohexane, and low-carbon fatty acids such as acetic acid, propionic acid and butyric acid.
Heavy impurities refer to materials having a boiling point higher than the boiling point of cyclohexanol under vacuum conditions (1-90 kPa), including but not limited to: alkyl cyclohexanols such as ethylcyclohexanol, propylcyclohexanol, cyclopentylcyclohexanol and cyclohexylcyclohexanol, alkyl cyclohexanones such as methylcyclohexanone, ethylcyclohexanone, propylcyclohexanone and butylcyclohexanone, alkylphenols such as phenol, cresol and ethylphenol, and alcohol ketone condensates such as cyclohexylcyclohexanone and cyclohexylcyclohexanol.
According to the method for preparing cyclohexanone by utilizing cyclohexanol dehydrogenation provided by the embodiment, the upstream incoming cyclohexanol is rectified by the normal pressure tower, the accumulated impurities in the middle of the cyclohexanol are separated, the refined cyclohexanol is subjected to dehydrogenation reaction, a crude alcohol ketone mixture is obtained, and the crude alcohol ketone mixture sequentially passes through the three reduced pressure rectifying towers of the light tower, the ketone tower and the alcohol tower, so that the light impurities in the crude alcohol ketone mixture are separated, a qualified cyclohexanone product and recycle alcohol are obtained, and part of heavy impurities are separated and discharged out of the device. Not only the intermediate accumulated impurities in the cyclohexanol raw material are separated out by utilizing normal pressure operation conditions, but also the normal pressure rectifying device and the decompression rectifying device are subjected to heat coupling utilization based on a condenser of the normal pressure tower, so that energy consumption is saved. Therefore, the method for preparing cyclohexanone by cyclohexanol dehydrogenation can improve the utilization rate of raw materials and the yield of products, reduce the generation of reaction byproducts and trace impurities, can be flexibly applied to cyclohexanone preparation processes of different processes, controls the content of accumulated impurities in the middle of a preparation system to be in a controllable range, has simple operation process and is easy for industrial amplification.
The process for preparing cyclohexanone by dehydrogenation of cyclohexanol according to the present invention is described below with reference to the accompanying drawings, but the present invention is not limited thereto.
The invention is further illustrated by the following examples, which are not intended to be limiting in any way.
Example 1
The device shown in figure 1 is adopted to prepare a cyclohexanone product by using cyclohexanol feed A, firstly, an atmospheric tower is used for removing intermediate accumulated impurities in the material A, the mass composition of main materials is shown in table 1, the equipment structural parameters of a light tower, a ketone tower and an alcohol tower are shown in table 3, the operating conditions and energy consumption of the atmospheric tower, the light tower, the ketone tower and the alcohol tower are shown in table 4, the cyclohexanol conversion rate of a dehydrogenation reaction unit can reach 49.6%, and the cyclohexanone selectivity can reach 98.1%.
Comparative example 1
The apparatus shown in FIG. 2 was used to prepare cyclohexanone product from cyclohexanol feed A, the mass composition of the main materials is shown in Table 2, the parameters of the equipment structures of the light tower, the ketone tower and the alcohol tower are shown in Table 3, and the operating conditions and energy consumption of the light tower, the ketone tower and the alcohol tower are shown in Table 4. Unlike example 1, crude cyclohexanol feedstock A was fed directly into a dehydrogenation reaction unit without purification treatment to yield a purified ketone product and recycle alcohol. The conversion rate of cyclohexanol in the dehydrogenation reaction unit can reach 47.6%, and the selectivity of cyclohexanone can reach 96.0%.
The specific process flow is as follows: the cyclohexanol feedstock 101' is directly fed into a dehydrogenation reaction unit for reaction to obtain an alcohol ketone mixture 120', and hydrogen 119' is discharged through a pipeline. Alcohol ketone mixture 120 'enters light column 12' from the middle, light column overhead 121 'can be in gas phase, flows through light column overhead condenser 13' and then is condensed into liquid phase 122', enters light column overhead reflux drum 14', light impurity 124 'and water 117' are separated and discharged, and residual stream 123 'flows back to the top of light column 12'. After a part of the alcohol ketone liquid phase 125 'of the tower kettle of the light tower 12' flows through the reboiler 15 'of the tower kettle of the light tower and is heated, the alcohol ketone liquid phase is gasified and returned to the light tower 12', and the other part of the alcohol ketone liquid phase 126 'enters the ketone tower 16'. The alcohol ketone liquid phase 126' enters the ketone column 16', the liquid phase stream 128' of the ketone column overhead gas phase material 127' after cooling by the ketone column overhead condenser 17' enters the ketone column overhead reflux drum 18' through a pipeline, a part of the liquid phase stream 129' returns to the ketone column 16' as reflux, and the other part is extracted as qualified ketone product 130 '. And the tower kettle material 131 'of the ketone tower kettle is heated by the ketone tower kettle reboiler 19', a part of tower kettle material 131 'is reboiled and flows back to the ketone tower 16', the other part of crude cyclohexanol 132 'containing part of cyclohexanone is discharged and enters the alcohol tower 20', the alcohol tower top gas-phase material 133 'enters the alcohol tower top condenser 21', the condensed liquid-phase flow 134 'enters the alcohol tower top reflux tank 22', a part of material 135 'returns to the alcohol tower 20' as reflux, the other part of material 135 'is extracted as recycle cyclohexanol 136', and the mixture of material and cyclohexanol material 101 'returns to the dehydrogenation reaction unit as mixed alcohol flow 105', and the reaction is further carried out. A portion of the bottoms stream 137 'is heated by bottoms reboiler 23' and then refluxed to bottoms column 20 'and another portion is withdrawn as heavy impurity 138'.
The energy consumption of the device in the example 1 is saved by 5.6% compared with that in the comparative example 1; the content of intermediate impurities in the recycle alcohol can be controlled to be 0.3%, while the content of intermediate impurities in the recycle alcohol in the comparative example is obviously increased to be 1.3%, so that the conversion rate of cyclohexanol reaction and the content of impurities in ketone products are affected.
In the description of the present application, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly, unless explicitly specified and limited otherwise. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.
The present application has been described in connection with the preferred embodiments, but these embodiments are merely exemplary and serve only as illustrations. On the basis of this, many alternatives and improvements can be made to the present application, which fall within the scope of protection of the present application.
Table 1 example 1 major material composition
Table 2 comparative example 1 major material composition
Table 3 comparison of example 1 and comparative example 1 device parameters
Table 4 example 1 and comparative example 1 operating conditions and energy consumption comparison
Claims (11)
1. An apparatus for preparing cyclohexanone by dehydrogenating cyclohexanol, comprising:
an atmospheric tower for reducing the content of intermediate accumulated impurities in the cyclohexanol material; the normal pressure tower is provided with a cyclohexanol raw material inlet; the top of the atmospheric tower is provided with a cyclohexanol material outlet for discharging cyclohexanol materials; the tower bottom of the atmospheric tower is provided with an intermediate accumulated impurity outlet for discharging cyclohexanol liquid containing intermediate accumulated impurities;
a dehydrogenation reaction unit for performing cyclohexanol dehydrogenation reaction; the dehydrogenation reaction unit is provided with a cyclohexanol material inlet and an alcohol ketone product material outlet; the cyclohexanol material inlet is communicated with a cyclohexanol material outlet of the atmospheric tower and is used for enabling the cyclohexanol material to enter the dehydrogenation reaction unit; the alcohol ketone product material outlet is used for discharging alcohol ketone mixture materials;
a light column for separating light impurities in the alcohol ketone mixture material; the light tower is provided with an alcohol-ketone mixture material inlet which is communicated with an alcohol-ketone product material outlet of the dehydrogenation reaction unit and is used for enabling the alcohol-ketone mixture material to enter the light tower; the top of the light tower is provided with a light impurity outlet for discharging light impurities in the alcohol-ketone mixture material; the light tower kettle is provided with an alcohol ketone liquid phase outlet for discharging an alcohol ketone liquid phase;
a ketone column for refining the alcohol ketone liquid phase; the ketone tower is provided with an alcohol ketone liquid phase inlet which is communicated with an alcohol ketone liquid phase outlet of the light tower and is used for enabling the alcohol ketone liquid phase to enter the ketone tower; the top of the ketone tower is provided with a cyclohexanone product outlet for extracting cyclohexanone products; the ketone tower kettle is provided with a crude cyclohexanol material outlet for discharging crude cyclohexanol material;
an alcohol tower for removing heavy impurities from the crude cyclohexanol material; the alcohol tower is provided with a crude cyclohexanol material inlet which is communicated with a crude cyclohexanol material outlet of the ketone tower and is used for enabling the crude cyclohexanol material to enter the alcohol tower; the top of the alcohol tower is provided with a circulating cyclohexanol material outlet which is communicated with one feed inlet of the dehydrogenation reaction unit and/or one feed inlet of the normal pressure tower.
2. The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol according to claim 1, wherein,
the apparatus further comprises an atmospheric tower condenser for heat exchanging cyclohexanol material from the atmospheric tower with an alcohol ketone liquid phase from the light tower bottoms or crude cyclohexanol material from the ketone tower bottoms or bottoms material from the alcohol tower bottoms in the atmospheric tower condenser.
3. The apparatus for producing cyclohexanone by dehydrogenation of cyclohexanol according to claim 2 wherein the cold-hot side temperature difference of the atmospheric tower condenser is not lower than 10 ℃.
4. The apparatus for producing cyclohexanone by dehydrogenation of cyclohexanol according to claim 1, wherein the content of intermediate accumulated impurities in the cyclohexanol material entering the dehydrogenation reaction unit is not higher than 50ppm based on total weight of the cyclohexanol material.
5. The apparatus for producing cyclohexanone by dehydrogenation of cyclohexanol according to claim 1, wherein the top operating pressure of the light column is 20-90kPa.
6. The apparatus for producing cyclohexanone by dehydrogenation of cyclohexanol according to claim 1 wherein the operation pressure of the ketone column and the alcohol column is 0.5-50kPa.
7. The apparatus for producing cyclohexanone by dehydrogenation of cyclohexanol according to claim 1, wherein the operating pressure of the atmospheric tower is 101-350kPa.
8. The apparatus for producing cyclohexanone by dehydrogenating cyclohexanol according to claim 1, wherein the intermediate accumulated impurity is a substance having a boiling point close to that of cyclohexanol under vacuum condition but a boiling point higher than that of cyclohexanol under normal pressure or pressure condition; the light impurity is a substance with a boiling point lower than or close to that of cyclohexanone under vacuum condition; the heavy impurities are substances with boiling points higher than the boiling point of cyclohexanol under vacuum conditions.
9. A process for the dehydrogenation of cyclohexanol to cyclohexanone, carried out in the apparatus for the dehydrogenation of cyclohexanol to cyclohexanone according to claim 1, comprising:
introducing cyclohexanol raw material into an atmospheric tower from a cyclohexanol raw material inlet for atmospheric distillation, discharging cyclohexanol liquid containing intermediate accumulated impurities from the bottom of the atmospheric tower through an intermediate accumulated impurity outlet, and discharging cyclohexanol material from the top of the atmospheric tower through a cyclohexanol material outlet;
enabling the cyclohexanol material to enter a dehydrogenation reaction unit through a cyclohexanol feed inlet of the dehydrogenation reaction unit, and carrying out dehydrogenation reaction in the dehydrogenation reaction unit to obtain an alcohol ketone product material;
enabling the alcohol ketone product material to enter a light tower through an alcohol ketone product material inlet of the light tower, removing light impurities and water in the alcohol ketone product material, and discharging an alcohol ketone liquid phase through an alcohol ketone liquid phase outlet of the light tower;
enabling the alcohol ketone liquid phase to enter a ketone tower through an alcohol ketone liquid phase inlet for refining, obtaining a cyclohexanone product at the top of the ketone tower, and extracting from a cyclohexanone product outlet; the crude cyclohexanol material is discharged via a crude cyclohexanol material outlet;
the crude cyclohexanol material enters the alcohol tower through a crude cyclohexanol material inlet to remove heavy impurities in the crude cyclohexanol; the recycle cyclohexanol material is discharged via a recycle cyclohexanol material outlet, which communicates with one feed inlet of the dehydrogenation reaction unit and/or one feed inlet of the atmospheric tower, such that the recycle cyclohexanol material is returned to the dehydrogenation reaction unit and/or the atmospheric tower.
10. The method of producing cyclohexanone by dehydrogenating cyclohexanol according to claim 9, further comprising heat-exchanging cyclohexanol material from an atmospheric tower with an alcohol ketone liquid phase from a light tower kettle or crude cyclohexanol material from a ketone tower kettle or tower kettle material from an alcohol tower kettle in the atmospheric tower condenser;
preferably, the cyclohexanol feed from the atmospheric tower is heat exchanged with the alcohol ketone liquid phase from the light ends tower.
11. The method for producing cyclohexanone by dehydrogenation of cyclohexanol according to claim 9, wherein the operating pressure of the atmospheric tower is 101-350kPa;
the top operating pressure of the light column is 20-90kPa;
the ketone column and the alcohol column are operated at a pressure of from 0.5 to 50kPa.
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| CN202111246478.9A CN116020143A (en) | 2021-10-26 | 2021-10-26 | Device and method for preparing cyclohexanone by cyclohexanol dehydrogenation |
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| CN202111246478.9A CN116020143A (en) | 2021-10-26 | 2021-10-26 | Device and method for preparing cyclohexanone by cyclohexanol dehydrogenation |
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