CN114874066B - Method and device for preparing alpha-methylstyrene by dehydrating 2-phenyl-2-propanol - Google Patents

Method and device for preparing alpha-methylstyrene by dehydrating 2-phenyl-2-propanol Download PDF

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CN114874066B
CN114874066B CN202210689139.6A CN202210689139A CN114874066B CN 114874066 B CN114874066 B CN 114874066B CN 202210689139 A CN202210689139 A CN 202210689139A CN 114874066 B CN114874066 B CN 114874066B
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reaction
catalyst layer
cumene
dehydration
propanol
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CN114874066A (en
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倪华方
顾维耀
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Shanghai Youcheng Gongyi Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
    • C07C1/20—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms
    • C07C1/24—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms by elimination of water
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/009—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping in combination with chemical reactions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/04—Purification; Separation; Use of additives by distillation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

Abstract

The invention provides a method and a production device for preparing alpha-methyl styrene (AMS) by utilizing 2-phenyl-2-propanol (DMBA) for dehydration. The method adopts the reaction rectifying tower capable of simultaneously carrying out dehydration reaction and dehydration rectification, realizes the functions of catalyzing dehydration, azeotropic rectification and split-phase dehydration of DMBA, can improve the dehydration efficiency, and realizes that the dehydration conversion rate of the DMBA reaches more than 95 percent under mild process conditions.

Description

Method and device for preparing alpha-methylstyrene by dehydrating 2-phenyl-2-propanol
Technical Field
The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method and a device of alpha-methylstyrene.
Background
Propylene Oxide (PO) is an important chemical raw material. Propylene oxide can be used for preparing polyether polyol, and plays an important role in the field of fine chemical engineering. Examples of chemical preparation methods of propylene oxide include chlorohydrin method, electrochemical chlorohydrin method, ethylbenzene indirect oxidation method, hydrogen peroxide direct oxidation method, and cumene oxidation method. Wherein, the chlorohydrin method can produce a large amount of chlorine-containing wastewater by the electrochemical chlorohydrin method, and the pollution is serious; the byproduct of the ethylbenzene indirect oxidation method is more; the hydrogen peroxide direct oxidation method needs a large amount of hydrogen peroxide as a raw material, and the current technology for preparing high-concentration hydrogen peroxide in China still has a plurality of defects. Compared with the preparation methods of the epoxypropane, the isopropylbenzene method has the advantages of environmental friendliness, low cost, few byproducts and no need of preparing hydrogen peroxide.
In the cumene process, 2-phenyl-2-propanol (DMBA) is an intermediate product in the propylene oxide production process of the cumene process. Cumene reacts with oxygen to form Cumene Hydroperoxide (CHP), which further reacts with propylene to form 2-phenyl-2-propanol (DMBA) and PO. Currently, there are two main directions for the subsequent treatment of DMBA: 1) And synthesizing dicumyl peroxide (DCP) to form PO and DCP co-production: in CN103212437, CHP and DMBA are used to generate DCP after condensation reaction and dehydration. However, the method has the defects of small production scale, low CHP conversion rate and the like. 2) And (3) recycling the hydrogenated cumene after AMS preparation. The method needs to be dehydrated to produce alpha-methyl styrene monomer (AMS) and then the AMS is subjected to hydrogenation treatment to produce isopropylbenzene for recycling.
There are two general methods for preparing AMS:
a process for preparing ethylbenzene by high-temp decomposition includes such steps as adding the mixture of DMBA and isopropylbenzene to reactor, heating to 200 deg.C and 0.5MPa or more, and decomposing and dewatering to obtain 80% of DMBA.
The other method is a catalytic dehydration process, a dehydration catalyst is adopted, the mixed solution of DMBA and isopropylbenzene is heated to 160 ℃, and the mixed solution is added into a reactor filled with the catalyst for 4 to 8 hours, so that the dehydration of DMBA can be realized, and the conversion rate of DMBA can reach 90 percent. WO0248126 mentions such a process, which has a relatively low dehydration temperature. However, this patent does not separate the water produced by the reaction as quickly as possible, resulting in a long reaction cycle and low efficiency.
Disclosure of Invention
To solve these problems, the present invention provides a method and apparatus for preparing α -methylstyrene (AMS) from 2-phenyl-2-propanol (DMBA) by dehydration.
In a first aspect, the present invention provides a process for preparing alpha-methylstyrene from 2-phenyl-2-propanol (DMBA) by dehydration. The method comprises the following steps: the mixed solution of the 2-phenyl-2-propanol and the isopropylbenzene enters a reactive distillation device, the 2-phenyl-2-propanol is dehydrated in the reactive distillation device in the presence of a catalyst for catalyzing the dehydration reaction, the isopropylbenzene and the water generated by the dehydration reaction are discharged from the reactive distillation device in a gas phase form, and the generated alpha-methylstyrene is discharged from the reactive distillation device in a liquid phase form.
The mass fraction of the 2-phenyl-2-propanol in the mixed liquid of the 2-phenyl-2-propanol and the isopropylbenzene is 10% -80%, preferably 30% -60%, such as 35%, 40%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% and the like.
In the method, preferably, the water and cumene are discharged from the reactive distillation apparatus in the form of an azeotrope. In one embodiment of the invention, water and cumene in the vapor phase are withdrawn from the top of the reactive distillation unit.
In the process, preferably, the azeotrope is further condensed to a liquid state to form a condensate.
According to the present invention, the catalyst is a dehydration catalyst commonly used in the art selected from the group consisting of commonly used solid acidic catalysts including, but not limited to, cation exchange resins (such as Amberlyst 15), zeolites, magnesium aluminum silicate molecular sieves, or alumina, and the like, preferably gamma-A1 2 O 3 . In a specific embodiment of the present invention, gamma-A1 is employed 2 O 3 Preferably, the bulk density is 0.3 to 1.0g/mL, for example 0.5g/mL, 0.6g/mL, 0.7g/mL, 0.8g/mL, 0.9g/mL. For example spherical gamma-A1 2 O 3 。
In the process, the dehydration reaction temperature is 120 to 200 ℃, preferably 130 to 185 ℃, for example 150 to 165 ℃,150 to 175 ℃,160 to 185 ℃.
In the method, the dehydration reaction pressure is 0.1 to 0.4MPa, preferably 0.15 to 0.3MPa, for example 0.15MPa,0.2MPa,0.21MPa,0.22MPa,0.23MPa,0.24MPa,0.25MPa,0.26MPa,0.27MPa,0.28MPa,0.29MPa,0.3MPa, etc.
According to the present invention, it is preferable that the dehydration reaction is carried out while the produced water and cumene are distilled off in the form of an azeotrope so that the water is separated from the produced alpha-methylstyrene.
In the method, the feeding amount is controlled to be 0.2-2.0h at the liquid hourly space velocity -1 Preferably 0.3 to 1.0h -1 . For example, 0.3h -1 ，0.4h -1 ，0.5h -1 ，0.6h -1 ，0.7h -1 ，0.8h -1 ，0.9h -1 。
In the method, preferably, the gas phase condensate is subjected to phase separation treatment, and is separated into an oil phase and a water phase, the water phase is discharged to a wastewater treatment unit, and the oil phase is cumene. In one embodiment of the invention, the phase separation treatment is carried out on the gas phase condensate using a phase separator, the residence time of the condensate in the phase separator being from 5 to 60 minutes, preferably from 10 to 20 minutes.
In the method, the time of contact of DMBA with the catalyst is preferably controlled so as to complete the catalytic dehydration reaction.
In the method, preferably, further, the separated isopropylbenzene is re-fed into a reaction rectifying device for reflux. In one embodiment of the invention, the refluxing cumene is heated before entering the reactive distillation apparatus. The refluxing cumene is heated to 100-140 c, preferably 120-135 c, such as 120 c, 121 c, 122 c, 123 c, 124 c, 125 c, 126 c, 127 c, 128 c, 129 c, 130 c, 131 c, 132 c, 134 c, 135 c.
According to the invention, a separation packing layer and a catalyst layer are sequentially arranged in the reaction rectifying device from top to bottom.
In some embodiments of the invention, the reactive distillation apparatus is a reactive distillation column. According to the invention, the height-to-diameter ratio of the reactive rectifying tower ranges from 5:1 to 10:1, for example from 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1, 6:1, 6.1:1, 6.2:1, 6.3:1, 6.4:1, 6.5:1, 6.6:1, 6.7:1, 6.8:1, 6.9:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1.
In some embodiments of the invention, the aspect ratio of the layer of separation filler is 0.8:1 to 2:1, such as 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1.
In some embodiments of the invention, the catalyst layer has an aspect ratio of 1.9:1 to 4:1, such as 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1. In one embodiment of the invention, the catalyst layer is a segment. In another embodiment of the present invention, the catalyst layer is two or more stages. Regardless of whether the catalyst layer is one-stage or multi-stage, the overall height to diameter ratio of the dehydration catalyst layer is 2:1 to 4:1.
The separation packing may use any packing and forms thereof known in the art including, but not limited to, wire mesh packing, structured plate corrugated packing, random packing such as raschig rings, pall rings, and the like.
In some embodiments of the invention, liquid distribution means are provided between the separation packing layer and the catalyst layer and/or between the sections of catalyst layer for the purpose of evenly distributing the liquid material.
In one embodiment of the invention, the mixed liquid of the 2-phenyl-2-propanol and the isopropylbenzene enters the device from the middle part of the reactive distillation device and flows downwards in the device through a catalyst layer arranged below a feeding position; the generated alpha-methyl styrene is discharged from the lower part of the reaction rectifying device in a liquid phase form; cumene and produced water pass upward through the separation packing layer and are discharged from the top of the reaction rectifying device in a gas phase form.
Preferably, the catalyst layer is two or more sections spaced apart. In the invention, the catalyst layers are arranged in a multi-stage form, and are sequentially called an upper-stage catalyst layer and a lower-stage catalyst layer from top to bottom according to the positions of each stage in the reaction rectifying device; or a first catalyst layer, a second catalyst layer, a third catalyst layer, and so on.
Preferably, the mixed liquid is heated when the temperature is lowered to a temperature unsuitable for dehydration reaction after the mixed liquid flows down through the catalyst layer. In one embodiment of the present invention, a heating member is installed between every two adjacent catalyst layers, and when the temperature of the mixed liquor flowing through the previous catalyst layer is lowered to a temperature unsuitable for dehydration reaction, the heating member may be turned on to heat the mixed liquor. In an embodiment of the invention, the heating element is a heating coil.
Preferably, a gas phase passage is provided in the catalyst layer outside the lowermost stage so that cumene and water in the gas phase rise. In the catalyst layer with the gas phase channels, one or more gas phase channels can be arranged in the catalyst layer, and the total cross-sectional area of the gas phase channels is not more than 15% of the internal cross-sectional area of the reactive distillation column, preferably 2% -10% of the internal cross-sectional area of the reactive distillation column.
In one embodiment of the invention, the mixed liquid of 2-phenyl-2-propanol and cumene enters the device from the lower part of the reactive distillation device, and flows upwards in the device through a catalyst layer arranged above a feeding position; the generated alpha-methyl styrene is discharged from the middle part of the reaction rectifying device in a liquid phase form; cumene and produced water pass upward through the separation packing layer and are discharged from the top of the reaction rectifying device in a gas phase form.
Preferably, the catalyst layer is a segment.
In one embodiment of the invention, the refluxing cumene enters the reactive distillation unit from above the layer of separation packing.
In one embodiment of the present invention, the heated aqueous cumene is used to raise the temperature within the reactive distillation unit to the dehydration reaction temperature prior to feeding the mixed liquor of 2-phenyl-2-propanol and cumene. The water content of the aqueous cumene is 5 to 15%, for example 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% and 14%.
The rational design of the present invention enables high DMBA conversion and high AMS selectivity to be achieved using the process of the present invention.
In a second aspect, the invention provides an apparatus for use in the method of preparation of the first aspect of the invention. The device comprises a reactive distillation device, a condensing device and a phase separation device; a dehydration catalyst layer is arranged in the reaction rectifying device, and a separation filler layer is arranged above the dehydration catalyst layer; the feed inlet of the reaction rectifying device is arranged below the separation packing layer, and the reaction rectifying device is provided with a gas phase discharge port above the separation packing layer. The condensing device is connected with a gas phase discharge port of the reaction rectifying device through a pipeline, and the phase separation device is connected with the condensing device through a pipeline.
In one embodiment of the invention, the reactive distillation apparatus is a reactive distillation column. According to the invention, the height-to-diameter ratio of the reactive rectifying tower ranges from 5:1 to 10:1, for example from 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1, 6:1, 6.1:1, 6.2:1, 6.3:1, 6.4:1, 6.5:1, 6.6:1, 6.7:1, 6.8:1, 6.9:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1.
In one embodiment of the invention, the aspect ratio of the layer of separation filler is 0.8:1 to 2:1, such as 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1.
In one embodiment of the invention, the height to diameter ratio of the dehydration catalyst layer is from 2:1 to 4:1, such as 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1. According to the present invention, the dehydration catalyst layer may be provided in one or more stages. In either arrangement, the overall height to diameter ratio of the dehydration catalyst layer is from 2:1 to 4:1.
Preferably, there is a spacing space between the layer of separation packing and the layer of dehydration catalyst.
When the catalyst layers are provided in multiple stages, a space is provided between each stage of catalyst layers.
In some embodiments of the invention, liquid distribution means are provided between the separation packing layer and the catalyst layer and/or between the sections of catalyst layer for the purpose of evenly distributing the liquid material.
In one embodiment of the present invention, the dehydration catalyst layer is provided in a multi-stage form, the feed port is provided above the catalyst layer of the uppermost stage, and the liquid phase discharge port is provided below the catalyst layer of the lowermost stage.
Preferably, a heating member is installed between every two adjacent catalyst layers, and when the temperature of the mixed solution flowing through the previous catalyst layer is lowered to a temperature unsuitable for dehydration reaction, the heating member may be turned on to heat the mixed solution. In an embodiment of the invention, the heating element is a heating coil.
Preferably, gas phase channels are distributed in the catalyst layer outside the lowermost stage. In the catalyst layer with the gas phase channels, one or more gas phase channels can be arranged in the catalyst layer, and the total cross-sectional area of the gas phase channels is not more than 15% of the internal cross-sectional area of the reactive distillation column, preferably 2% -10% of the internal cross-sectional area of the reactive distillation column.
In one embodiment of the invention, the dehydration catalyst layer is in the form of a two-stage arrangement. The feed inlet is arranged above the upper section catalyst layer, and the liquid phase discharge outlet is arranged below the lower section catalyst layer. A heating member (e.g., a heating coil) is installed in the space between the two catalyst layers. The upper section of the catalyst layer is distributed with one or more gas phase channels, the total cross-sectional area of the gas phase channels is not more than 15 percent of the internal cross-sectional area of the reactive distillation column, and is preferably 2 to 10 percent of the internal cross-sectional area of the reactive distillation column.
In another embodiment of the invention, the dehydration catalyst layer is in the form of a single stage arrangement, the feed inlet being arranged below the catalyst layer, and the liquid phase discharge being arranged between the separation packing layer and the catalyst layer.
According to the invention, the water outlet of the phase separation device is connected via a line to a device for storing or treating waste water. In some embodiments of the invention, the phase separation device is a phase separator. Preferably, the aspect ratio of the phase separator is from 1.5:1 to 3:1, such as 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1.
According to the invention, the apparatus further comprises a raw material heating device. The raw material heating device is connected with a feed inlet of the reaction rectifying device through a pipeline.
According to the invention, the device further comprises a raw material storage device. The raw material storage device is connected with the raw material heating device through a pipeline.
According to the invention, the device also comprises a device for heating and refluxing the cumene. The heating device is connected with an oil phase discharge port of the phase separation device through a pipeline. In one embodiment of the invention, the heating device is referred to as a reflow heater.
According to the invention, the discharge port of the heating device for refluxing the cumene is connected with the reflux material feed port of the reaction rectifying device through a pipeline, and the reflux material feed port is arranged above the separation packing layer.
According to the present invention, the raw material heating device and the reflux cumene heating device can each employ various heating devices commonly used in the art, including but not limited to a tube-in-tube heat exchanger and the like.
The invention has the following beneficial effects:
1. the reaction rectifying device with dehydration reaction and dehydration rectification simultaneously can realize the function of removing the reaction generated water in real time while the catalytic dehydration reaction of DMBA is carried out in one device. The inventors found that controlling the moisture in the reaction system to be kept at a low level at all times will allow the dehydration reaction to proceed continuously and rapidly. Correspondingly, the industrial practice of dehydration after reaction results in low dehydration efficiency and long time consumption.
2. The dehydration mode of the invention adopts an azeotropic distillation mode, which can greatly improve the dehydration efficiency, reduce the energy consumption and reduce the equipment investment.
3. The process has mild reaction condition, the dehydration conversion rate of DMBA reaches more than 95%, continuous operation can be realized, industrial amplification is easy, and the process has huge commercial value.
In the present invention, the aspect ratio refers to the length ratio of the height and diameter of the corresponding structure or device. Aspect ratio refers to the length to diameter ratio of the length and diameter of the corresponding structure or device.
In the present invention, unless otherwise specified, the pressures are gauge pressures.
Drawings
FIG. 1 is a schematic diagram of one embodiment of the process and apparatus of the present invention, wherein A: charging bucket, B: feed pump, C: raw material heater, D: reactive rectifying tower, D1: separation filler layer, D2: a first catalyst layer, D3: two-stage catalyst layer, D4: gas phase channel, D5: heating coil, E: condenser, F: phase separator, G: reflux pump, H: reflow heater
Fig. 2 is a schematic diagram of another embodiment of the process and apparatus of the present invention, wherein a: charging bucket, B: feed pump, C: raw material heater, D: reactive rectifying tower, D1: separation filler layer, D4: catalyst layer, E: condenser, F: phase separator, G: reflux pump, H: reflow heater
Detailed Description
Fig. 1 illustrates one embodiment of the process and apparatus of the present invention. In the reactive rectifying column D, two dehydration catalyst layers, namely a first catalyst layer D2 and a second catalyst layer D3, are provided, wherein D3 is below D2. A layer of separation packing D1 is disposed over a section of catalyst layer D2. The raw material feed inlet is arranged below D1, the gas phase discharge outlet is arranged above D1, and the liquid phase discharge outlet is arranged below D3. A gas phase passage D4 is provided in D2, and a heating coil D5 is provided between D2 and D3.
The gas phase discharge port of the reaction rectifying tower D is connected with a condenser E through a pipeline, the E is connected with a phase separator F through a pipeline, the oil phase discharge port of the F is connected with a reflux pump G through a pipeline, and the G is connected with a reflux heater H through a pipeline. H is connected with a reflux feed inlet above D1 through a pipeline.
The material tank A is a raw material storage device and is used for storing raw materials for reaction, the raw materials A are connected with the feed pump B through pipelines, the raw materials B are connected with the raw material heater C through pipelines, and the raw materials C are connected to a feed inlet of the reaction rectifying tower D through pipelines.
The mixed solution of 2-phenyl-2-propanol and cumene (hereinafter also referred to as "reaction solution") is stored in a feed tank A, is fed to a raw material heater C through a feed pump B, is heated to a temperature suitable for reaction, and is fed into a reactive rectifying column D through a feed port. The reaction solution passes through the first-stage catalyst layer D2, is appropriately heated by the heating coil D5, and then passes through the second-stage catalyst layer D3.
After the reaction product passes through the separation packing layer D1, the azeotrope (gas phase) of water and isopropylbenzene is discharged from a gas phase discharge port at the top of the D and is sent to a condenser E, the condensate is sent to a phase separator F, the oil-phase isopropylbenzene and the water phase are separated in the phase separator F, the water phase is discharged to a wastewater treatment device, the oil phase is sent to a reflux heater H through a reflux pump G, and the heated oil phase is refluxed into a reaction rectifying tower D.
The liquid phase in the reaction product is withdrawn from the bottom of the reactive distillation column, which is a mixture of cumene and AMS.
In a specific embodiment of the invention, a liquid distributor may also be installed between D1 and D2, between D2 and D3.
Fig. 2 illustrates another embodiment of the process and apparatus of the present invention. In the reactive rectifying column D, a dehydration catalyst layer D4 in a one-stage form is provided, and a separation packing layer D1 is provided above the dehydration catalyst layer D4. The raw material feed inlet is arranged below D4, the gas phase discharge outlet is arranged above D1, and the liquid phase discharge outlet is arranged above D4.
The gas phase discharge port of the reaction rectifying tower D is connected with a condenser E through a pipeline, the E is connected with a phase separator F through a pipeline, the oil phase discharge port of the F is connected with a reflux pump G through a pipeline, and the G is connected with a reflux heater H through a pipeline.
The material tank A is used for storing raw materials for reaction, the material tank A is connected with the feed pump B through a pipeline, the material tank B is connected with the raw material heater C through a pipeline, and the raw material heater C is connected to the feed inlet of the reaction rectifying tower D through a pipeline.
The mixed solution of 2-phenyl-2-propanol and cumene (hereinafter also referred to as "reaction solution") is stored in a feed tank A, is fed to a raw material heater C through a feed pump B, is heated to a temperature suitable for reaction, and is fed into a reactive rectifying column D through a feed port. The reaction solution was subjected to dehydration reaction through the catalyst layer D4.
After the reaction product passes through the separation packing layer D1, the azeotrope of water and isopropylbenzene is discharged from a gas phase discharge port at the top of the D and is sent to a condenser E, the condensate is sent to a phase separator F, the oil-phase isopropylbenzene and the water phase are separated in the phase separator F, the water phase is discharged to a wastewater treatment device, the oil phase is sent to a reflux heater H through a reflux pump G, and the heated oil phase is refluxed and enters a reaction rectifying tower.
The liquid phase in the reaction product is withdrawn from above D4, which is a mixture of cumene and AMS.
In a specific embodiment of the invention, a liquid distributor may also be installed between D1 and D4.
The two processes and devices shown in fig. 1 and fig. 2 can achieve the expected effect, wherein the process and device represented in fig. 2 have stronger practicability and simpler equipment than those of fig. 1.
Example 1:
the reaction device is built according to the process flow and the device sequence of the attached figure 1, wherein: the diameter of the reaction rectifying tower D is 0.5m, the total height of the reaction rectifying tower D is 3.3m, the catalyst layer in the reaction rectifying tower is divided into two sections, namely a first section of catalyst layer D2 and a second section of catalyst layer D3, each section is 0.5m, and a gas phase channel of DN100 is reserved in the first section of catalyst layer D2. Reactive distillationThe upper separation packing layer D1 above D2 of the column was packed with MELLPACK 252 packing at a height of 0.6m. The reaction rectifying tower is internally provided with a liquid distributor between D1 and D2 and between D2 and D3, and the design of the liquid distributor is the conventional tower design. The catalyst is spherical and has main component gamma-A1 2 O 3 4-8 mm in diameter and bulk density of about 0.7g/mL. The raw material heater C and the reflux heater H are all tubular heat exchangers, and the heat exchange area of the raw material heater C is 0.66m 2 Heat exchange area of H0.52 m 2 . The heating coil D5 in the middle of the reactive distillation column is a coil with the diameter DN20, and the heat exchange area is 0.26m 2 . Phase separator F volume 15L, aspect ratio 2:1, a step of; the feeding pump B and the reflux pump G are metering pumps, and the flow range is 50-200L/h; the volume of the charging bucket A is 200L.
Security inspection and N of the whole device 2 After purging and replacement, firstly adding cumene with 10% of water into the system, and heating by a raw material heat exchanger C and a reflux heater H to ensure that the temperature in the reaction rectifying tower is raised to 160-165 ℃ and the pressure is controlled to be 0.2MPa. Then according to the liquid hourly space velocity for 0.5h -1 To the reaction rectifying column was added a cumene solution of 50% dmba (hereinafter also referred to as "reaction liquid"). The feed temperature was controlled at 160 c and the reflux temperature was controlled at 125 c by controlling the flow of steam. After the reaction liquid passes through the first-stage catalyst layer D2, the temperature is reduced from 160 ℃ to about 150 ℃, the reaction liquid is heated to 158-160 ℃ through a heating coil D5 and enters the second-stage catalyst layer D3, and the discharge temperature of the tower kettle is 153 ℃. Samples were taken from the bottom of the column to analyze the DMBA content. The concentration changes of DMBA, AMS and impurities were determined by gas chromatography. The conversion was calculated by the change in peak area of DMBA. The selectivity of AMS was calculated from the ratio of the peak area of the product AMS to the sum of the peak areas of the product AMS and the impurities. The conversion of DMBA was found to be 98.2% by assay. AMS selectivity was greater than 99.6%.
Example 2:
adjusting the feeding flow rate to ensure that the liquid hourly space velocity is 0.4h -1 Other conditions were the same as in example 1, and the DMBA content was analyzed by sampling from the bottom of the column. Analysis revealed that the conversion of DMBA was 99.1%. AMS selectivity was greater than 99.6%.
Example 3:
adjusting the feeding flow rate to ensure that the liquid hourly space velocity is 0.6h -1 Other conditions were the same as in example 1, and the DMBA content was analyzed by sampling from the bottom of the column. Analysis revealed a conversion of DMBA of 97.3%. AMS selectivity was greater than 99.6%.
Example 4:
adjusting the feeding flow rate to ensure that the liquid hourly space velocity is 0.8h -1 Other conditions were the same as in example 1, and the DMBA content was analyzed by sampling from the bottom of the column. Analysis revealed a conversion of 92.8% DMBA. AMS selectivity was greater than 99.6%.
Example 5:
the apparatus and conditions according to example 1 were the same except that the temperature was raised by the feed heat exchanger C and the reflux heater H so that the temperature in the reactive distillation column was 180 to 185℃and the pressure was controlled at 0.25MPa. Then according to the liquid hourly space velocity for 0.6h -1 To the reaction rectifying column was added a 50% dmba in cumene solution. The feed temperature was controlled at 180℃by controlling the flow of steam and the reflux temperature was controlled at about 130 ℃. After the reaction liquid passes through the first catalyst layer D2, the temperature is reduced from 180 ℃ to 169 ℃ or so, a heating coil D5 is not started, and the discharge temperature of the tower kettle is 163 ℃. Samples were taken from the bottom of the column to analyze the DMBA content. Analysis revealed a DMBA conversion of 99.3%. AMS selectivity was greater than 99.4%.
Example 6:
the reaction device is built according to the process flow and the device sequence of the figure 2, wherein: the diameter of the reactive rectifying tower D is 0.5m, the total height is 3.3m, and the height of the catalyst layer D4 in the separating tower is 1.2m. The separation packing layer D1 above D4 in the upper part of the reactive distillation column is filled with MELLPACK 252 packing, with a height of 0.6m. A liquid distributor is arranged between D1 and D4 in the reactive distillation column, and the design is according to the conventional column design. The catalyst is spherical and has main component gamma-A1 2 O 3 4-8 mm in diameter and bulk density of about 0.7g/mL. The raw material heater C and the reflux heater H are all tubular heat exchangers, and the heat exchange area of the raw material heater C is 0.66m 2 Heat exchange area of H0.52 m 2 . Phase separator F volume 15L, aspect ratio 2:1, a step of; the feeding pump B and the reflux pump G are metering pumps, and the flow range is 50-200L/h; the volume of the charging bucket A is 200L.
Security inspection and N of the whole device 2 After purging and replacement, firstly adding cumene with 10% of water into the system, and heating by a raw material heat exchanger C and a reflux heater H to ensure that the temperature in the reaction rectifying tower is 180-185 ℃ and the pressure is controlled at 0.25MPa. Then according to the liquid hourly space velocity for 0.6h -1 To the reaction rectifying column was added a 50% dmba in cumene solution. The feed temperature was controlled at 180℃and the reflux temperature was controlled at 130℃by controlling the flow of steam. After the reaction solution passed through the catalyst layer D4, the temperature was lowered from 180 ℃ to about 162 ℃. The product material was withdrawn from the upper part of the catalyst layer D4 by liquid level control in the column, and the DMBA content was sampled and analyzed. Analysis revealed that the conversion of DMBA was 99.6%. AMS selectivity was greater than 99.6%.
Example 7
The apparatus and conditions according to example 6 were the same except that the temperature was raised by the feed heat exchanger C and the reflux heater H so that the temperature in the reactive distillation column was 170 to 175℃and the pressure was controlled at 0.2MPa. Then according to the liquid hourly space velocity for 0.6h -1 To the reaction rectifying column was added a 50% dmba in cumene solution. The feed temperature was controlled at 170 c and the reflux temperature was controlled at about 125 c by controlling the flow of steam. After the reaction solution passed through the catalyst D4, the temperature was lowered from 170℃to about 153 ℃. The product material was withdrawn from the upper part of the catalyst layer D4 by liquid level control in the column, and the DMBA content was sampled and analyzed. Analysis revealed a DMBA conversion of 98.5%. AMS selectivity was greater than 99.5%.
Example 8
The apparatus and conditions according to example 7 were followed, except that the height of the layer of the separation packing was reduced from 0.6m to 0.4m. And (3) through the dehydration reaction and separation, extracting a product material from the upper part of the catalyst layer D4, and sampling and analyzing the content of DMBA to obtain the following components: the conversion of DMBA was 98.6% and AMS selectivity was greater than 99.5%.
Example 9
The apparatus and conditions according to example 1 were followed, except that the separation packing layer height was increased from 0.6m to 1m, and the reaction conditions were kept the same as those of example 1. And (3) carrying out dehydration reaction and separation, and obtaining the content of DMBA by sampling analysis from the bottom discharge of the tower: the conversion of DMBA was 98.3% and AMS selectivity was greater than 99.5%.
Example 10
The apparatus and conditions according to example 6 were followed, except that the filler layer height was lowered from 0.6m to 0.4m, the catalyst layer D4 height was raised from 1.2m to 1.8m, and the reaction conditions were kept consistent with those of example 6. And (3) through the dehydration reaction and separation, extracting a product material from the upper part of the catalyst layer D4, and sampling and analyzing the content of DMBA to obtain the following components: the conversion of DMBA was 99.7% and AMS selectivity was greater than 99.5%.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (17)

1. A method for preparing alpha-methylstyrene by dehydrating 2-phenyl-2-propanol is characterized in that a mixed solution of 2-phenyl-2-propanol and isopropylbenzene enters a reaction rectifying device, the 2-phenyl-2-propanol is dehydrated in the reaction rectifying device in the presence of a catalyst for catalyzing the dehydration reaction, water generated by the dehydration reaction and isopropylbenzene are discharged from the reaction rectifying device in a gas phase form in an azeotrope form, and the generated alpha-methylstyrene is discharged from the reaction rectifying device in a liquid phase form;
the mass fraction of the 2-phenyl-2-propanol in the mixed solution of the 2-phenyl-2-propanol and the isopropylbenzene is 30-60%;
the dehydration reaction temperature is 120-200 ℃; the dehydration reaction pressure is 0.1-0.4MPa;
the feeding amount is controlled to be 0.2 to 2.0 hours of liquid hourly space velocity -1 ；
A separation packing layer and a catalyst layer are sequentially arranged in the reaction rectifying device from top to bottom; the reaction rectifying device is a reaction rectifying tower, and the height-diameter ratio of the reaction rectifying tower ranges from 5:1 to 10:1; the height-diameter ratio of the separation filler layer is 0.8:1-2:1; the height-diameter ratio of the catalyst layer is 2:1-4:1.
2. The method of claim 1, wherein the dehydration reaction temperature is 130 to 185 ℃.
3. The method of claim 1, wherein the dehydration reaction pressure is from 0.15MPa to 0.3MPa.
4. The method according to claim 1, wherein the feed amount is controlled at a liquid hourly space velocity of 0.3 to 1.0h -1 。
5. The method of any of claims 1-4, wherein the catalyst layer is a segment.
6. The method of any of claims 1-4, wherein the catalyst layer is two or more segments.
7. The method according to claim 6, wherein the mixed liquid of 2-phenyl-2-propanol and cumene enters the device from the middle part of the reactive distillation device, and flows downwards in the device through a catalyst layer arranged below the feeding position; the generated alpha-methyl styrene is discharged from the lower part of the reaction rectifying device in a liquid phase form; cumene and produced water pass upward through the separation packing layer and are discharged from the top of the reaction rectifying device in a gas phase form.
8. The method of claim 7, wherein the mixed liquor is heated when the temperature of the mixed liquor decreases to a temperature unsuitable for dehydration after passing down through the catalyst layer.
9. The method according to claim 7, wherein a gas phase passage is provided in the catalyst layer outside the lowermost stage so as to raise cumene and water in the gas phase; in the catalyst layer with gas phase channels, one or more gas phase channels are arranged in the catalyst layer, and the total cross section area of the gas phase channels is not more than 15% of the inner cross section area of the reactive rectifying tower.
10. The method of claim 9, wherein the total cross-sectional area of the gas phase channels is 2% to 10% of the internal cross-sectional area of the reactive distillation column.
11. The method of claim 7, wherein a liquid distribution member is provided between the separation packing layer and the catalyst layer and/or between the catalyst layers of each segment to uniformly distribute the liquid material.
12. The method according to claim 5, wherein the mixed liquid of 2-phenyl-2-propanol and cumene enters the reaction rectifying device from the lower part of the device, and flows upwards in the device through a catalyst layer arranged above the feeding position; the generated alpha-methyl styrene is discharged from the middle part of the reaction rectifying device in a liquid phase form; cumene and produced water pass upward through the separation packing layer and are discharged from the top of the reaction rectifying device in a gas phase form.
13. The process of any one of claims 1-4, wherein the azeotrope condenses to a liquid form a condensate; the condensate is subjected to phase separation treatment and is divided into an oil phase and a water phase.
14. The method of claim 13, wherein the separated cumene is re-fed to a reactive distillation unit for reflux; and the refluxing isopropylbenzene enters the reaction rectifying device from the upper part of the separation packing layer.
15. The method of claim 14, wherein the refluxed cumene is heated to 100-140 ℃ after being passed through a heat treatment and then fed to a reactive distillation unit.
16. The method of claim 15, wherein the refluxing cumene is heated to 120-135 ℃.
17. The method according to any one of claims 1 to 4, wherein the heated aqueous cumene is used to raise the temperature in the reactive distillation apparatus to the dehydration reaction temperature prior to feeding the mixture of 2-phenyl-2-propanol and cumene; the moisture content of the hydrous isopropylbenzene is 5-15%.
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