CN114874066A - Method and device for preparing alpha-methyl styrene by dehydrating 2-phenyl-2-propanol - Google Patents

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

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CN114874066A
CN114874066A CN202210689139.6A CN202210689139A CN114874066A CN 114874066 A CN114874066 A CN 114874066A CN 202210689139 A CN202210689139 A CN 202210689139A CN 114874066 A CN114874066 A CN 114874066A
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catalyst layer
reaction
cumene
reactive distillation
phase
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CN114874066B (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
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Abstract

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

Description

Method and device for preparing alpha-methyl styrene 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. The propylene oxide can be used for preparing polyether polyol and occupies an important position in the field of fine chemical engineering. The chemical preparation method of the propylene oxide comprises a chlorohydrin method, an electrochemical chlorohydrin method, an ethylbenzene indirect oxidation method, a hydrogen peroxide direct oxidation method, a cumene oxidation method and the like. Among them, the chlorohydrin method and electrochemical chlorohydrin method can produce a large amount of chlorine-containing wastewater, and the pollution is serious; the ethylbenzene indirect oxidation method has more byproducts; the direct hydrogen peroxide oxidation method needs a large amount of hydrogen peroxide as a raw material, and the current process for preparing high-concentration hydrogen peroxide in China still has a plurality of defects. Compared with the above propylene oxide preparation methods, the cumene 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 production of propylene oxide by the cumene process. Cumene and oxygen react 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 processing of DMBA: 1) synthesizing and preparing dicumyl peroxide (DCP) to form PO and DCP for co-production: CN103212437, CHP and DMBA are condensed and dehydrated to generate DCP. However, the method has the defects of small production scale, low CHP conversion rate and the like. 2) And (3) preparing the cumene by hydrogenation after preparing the AMS for recycling. In this direction, alpha-methyl styrene monomer (AMS) is produced by dehydration, and then the AMS is hydrogenated to produce cumene for recycling.
There are two common methods used to prepare AMS:
one is high temperature decomposition, adding the mixture of DMBA and isopropyl benzene into a reactor, heating to 200 deg.C, and the pressure is above 0.5MPa, the DMBA is decomposed and dehydrated, the conversion rate can reach 80%, the cost of the process equipment is high, the by-products are more, and the part of AMS generated at high temperature can be converted into ethylbenzene.
The other method is a catalytic dehydration process, a dehydration catalyst is adopted, the mixed solution of DMBA and cumene is heated to 160 ℃, and is added into a reactor filled with the catalyst for processing for 4-8 hours, the dehydration of the DMBA can be realized, and the conversion rate of the DMBA can reach 90%. WO0248126 mentions this process, which has a lower dehydration temperature. However, the patent does not separate the water generated in the reaction as soon as possible, which results in long reaction period and low efficiency.
Disclosure of Invention
To solve these problems, the present invention provides a method and a production apparatus for preparing alpha-methylstyrene (AMS) by dehydrating 2-phenyl-2-propanol (DMBA).
In a first aspect of the present invention, there is provided a method for preparing alpha-methylstyrene by dehydrating 2-phenyl-2-propanol (DMBA). The method comprises the following steps: the mixed liquid of the 2-phenyl-2-propanol and the isopropylbenzene enters a reaction rectifying device, the 2-phenyl-2-propanol carries out dehydration reaction in the reaction rectifying device in the presence of a catalyst for catalyzing dehydration reaction, the isopropylbenzene and water generated by the dehydration reaction are discharged from the reaction rectifying device in a gas phase form, and the generated alpha-methyl styrene is discharged from the reaction rectifying device in a liquid phase form.
The mass fraction of 2-phenyl-2-propanol in the mixed solution of 2-phenyl-2-propanol and cumene is 10% to 80%, preferably 30% to 60%, for example, 35%, 40%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, etc.
In the process, water and cumene are preferably discharged from the reactive distillation unit in the form of an azeotrope. In one embodiment of the invention, water and cumene in gas phase are withdrawn from the top of the reactive rectification unit.
In the method, preferably, the azeotrope is further condensed into a liquid state to form a condensate.
According to the invention, the catalyst is a dehydration catalyst commonly used in the art, selected from common 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 invention, gamma-A1 is used 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, 0.9 g/mL. Such as spherical gamma-A1 2 O 3 。
In the method, the dehydration reaction temperature is 120-200 ℃, preferably 130-185 ℃, such as 150-165 ℃, 150-175 ℃ and 160-185 ℃.
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 preferred that the dehydration reaction is carried out while the water produced is distilled off azeotropically with cumene, so that water is separated from the alpha-methylstyrene produced.
In the method, the feeding amount is controlled at the liquid hourly space velocity of 0.2-2.0h -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 to be divided 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 of the gas-phase condensate is carried out using a phase separator, the residence time of the condensate in the phase separator being from 5 to 60min, preferably from 10 to 20 min.
In the method, the catalytic dehydration reaction is preferably completed by controlling the time of contacting the DMBA with the catalyst.
In the method, preferably, the separated cumene is further fed into the reaction rectifying device again for reflux. In one embodiment of the invention, the refluxed cumene is subjected to a heat treatment before entering the reactive distillation unit. The refluxed cumene is heated to a temperature of 100-140 deg.C, preferably 120-135 deg.C, such as 120 deg.C, 121 deg.C, 122 deg.C, 123 deg.C, 124 deg.C, 125 deg.C, 126 deg.C, 127 deg.C, 128 deg.C, 129 deg.C, 130 deg.C, 131 deg.C, 132 deg.C, 134 deg.C, 135 deg.C.
According to the invention, the separation packing layer and the catalyst layer are sequentially arranged in the reaction rectification 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-diameter ratio of the reactive distillation column is in the range of 5:1 to 10:1, for example, 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 and 9.5: 1.
In some embodiments of the invention, the aspect ratio of the separation packing layer 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 pieces. No matter the catalyst layer is one-section or multi-section, the height-diameter ratio of the total dehydration catalyst layer is 2: 1-4: 1.
The separation packing may use any packing known in the art and forms thereof, 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, a liquid distribution member is disposed between the separation packing layer and the catalyst layer, and/or between each catalyst layer, to achieve the purpose of uniformly distributing the liquid material.
In one embodiment of the invention, the mixed liquid of 2-phenyl-2-propanol and isopropyl benzene 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; discharging the generated alpha-methyl styrene from the lower part of the reaction rectification device in a liquid phase form; the cumene and the generated water pass upwards through a 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 spaced-apart catalyst layers. In the invention, the catalyst layers arranged in a multi-section mode are sequentially called an upper-section catalyst layer and a lower-section catalyst layer from top to bottom according to the positions of all sections 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 of the mixed liquid is lowered to a temperature unsuitable for the dehydration reaction after flowing 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 liquid passing through the previous catalyst layer is lowered to a temperature unsuitable for the dehydration reaction, the heating member may be turned on to heat the mixed liquid. In an embodiment of the invention, the heating element is a heating coil.
Preferably, a gas phase passage is provided in the catalyst layer other than the lowermost stage so as to allow cumene and water in the gas phase to rise. In the catalyst layer with the gas-phase channels, the gas-phase channels in the catalyst layer can be one or more, 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, and 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 reaction rectification device and flows upwards in the device through a catalyst layer arranged above the feeding position; discharging the generated alpha-methyl styrene from the middle part of the reaction rectification device in a liquid phase form; the cumene and the generated water pass upwards through a separation packing layer and are discharged from the top of the reaction rectifying device in a gas phase form.
Preferably, the catalyst layer is one segment.
In one embodiment of the invention, the refluxed cumene enters the reactive distillation unit from above the separation packing layer.
In one embodiment of the present invention, the temperature in the reactive distillation apparatus is raised to the dehydration reaction temperature using heated aqueous cumene before feeding the mixed liquid of 2-phenyl-2-propanol and cumene. The water content of the hydrous cumene is 5 to 15%, for example, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%.
The rational design of the invention enables high DMBA conversion and high AMS selectivity to be achieved using the method of the invention.
In a second aspect, the present invention provides an apparatus for use in the method of the first aspect of the present invention. The device comprises a reaction rectification device, a condensation device and a phase separation device; a dehydration catalyst layer is arranged in the reaction rectification device, and a separation packing layer is arranged above the dehydration catalyst layer; the reaction rectifying device is characterized in that a feed inlet of the reaction rectifying device is arranged below the separation packing layer, and a gas phase discharge outlet is arranged 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-diameter ratio of the reactive distillation column is in the range of 5:1 to 10:1, for example, 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 present invention, the aspect ratio of the separation packing layer is 0.8:1 to 2:1, for example, 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 present invention, the dehydration catalyst layer has a height to diameter ratio of 2:1 to 4:1, for example, 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 any arrangement form, the height-diameter ratio of the total dehydration catalyst layer is 2: 1-4: 1.
Preferably, a space is provided between the separation packing layer and the dehydration catalyst layer.
When the catalyst layers are arranged in multiple stages, there are spaces between the catalyst layers in each stage.
In some embodiments of the invention, a liquid distribution member is disposed between the separation packing layer and the catalyst layer, and/or between each catalyst layer, to achieve the purpose of uniformly distributing the liquid material.
In one embodiment of the present invention, the dehydration catalyst layer is provided in a multi-stage arrangement, the feed port is provided above the uppermost catalyst layer, and the liquid phase discharge port is provided below the lowermost catalyst layer.
Preferably, a heating member is installed between every two adjacent catalyst layers, and when the temperature of the mixed liquid passing through the previous catalyst layer is lowered to a temperature unsuitable for the dehydration reaction, the heating member may be turned on to heat the mixed liquid. 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 section. In the catalyst layer with the gas-phase channels, the gas-phase channels in the catalyst layer can be one or more, 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, and 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 a two-stage arrangement. The feed inlet is arranged above the upper catalyst layer, and the liquid phase discharge outlet is arranged below the lower catalyst layer. A heating element (e.g., a heating coil) is installed in the space between the two catalyst layers. Gas phase channels are distributed in the upper catalyst layer, the number of the gas phase channels is one or more, 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, and preferably 2% -10% of the internal cross-sectional area of the reactive distillation column.
In another embodiment of the present invention, the dehydration catalyst layer is provided in a single stage, the feed port is provided below the catalyst layer, and the liquid phase discharge port is provided between the separation packing layer and the catalyst layer.
According to the invention, the aqueous phase discharge of the phase separation apparatus is connected via a line to an apparatus 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 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 device also comprises a raw material heating device. The raw material heating device is connected with the feed inlet of the reaction rectifying device through a pipeline.
According to the invention, the device also 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 plant also comprises a means 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 reflux heater.
According to the invention, the discharge hole of the heating device for refluxing cumene is connected with the reflux material feed inlet of the reaction rectifying device through a pipeline, and the reflux material feed inlet is arranged above the separation packing layer.
According to the present invention, the raw material heating device and the reflux cumene heating device can adopt various heating devices commonly used in the field, including but not limited to a tubular heat exchanger and the like.
The invention has the following beneficial effects:
1. by adopting the reaction rectification device with dehydration reaction and dehydration rectification, the function of removing water generated by reaction in real time while carrying out catalytic dehydration reaction on DMBA in one device can be realized. The inventors have found that controlling the water content in the reaction system to be always kept at a low level allows the dehydration reaction to proceed continuously and rapidly. Correspondingly, the industrial practice of dehydration after reaction leads to low efficiency and long time consumption of dehydration reaction.
2. The dehydration mode of the invention adopts the azeotropic rectification mode, which can greatly improve the dehydration efficiency, reduce the energy consumption and reduce the equipment investment.
3. The process has mild reaction conditions, the dehydration conversion rate of DMBA reaches more than 95 percent, can realize continuous operation, is easy for industrial amplification and has great commercial value.
In the present invention, the aspect ratio refers to a length ratio of a height and a diameter of a corresponding structure or device. Aspect ratio refers to the ratio of the length to the 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: a material tank, B: a feed pump, C: raw material heater, D: reactive rectification column, D1: separation packing layer, D2: one-stage catalyst layer, D3: two-stage catalyst layer, D4: gas phase channel, D5: heating coil, E: a condenser, F: phase separator, G: reflux pump, H: reflux heater
FIG. 2 is a schematic diagram of another embodiment of the process and apparatus of the present invention, wherein A: a material tank, B: a feed pump, C: raw material heater, D: reactive rectification column, D1: separation packing layer, D4: catalyst layer, E: a condenser, F: phase separator, G: reflux pump, H: reflux heater
Detailed Description
FIG. 1 illustrates one embodiment of the process and apparatus of the present invention. In the reactive distillation column D, two dehydration catalyst layers are arranged, namely a first catalyst layer D2 and a second catalyst layer D3, and D3 is arranged below D2. A separation filler layer D1 is provided above the first stage catalyst layer D2. The feed inlet was placed below D1, the gas phase discharge outlet was placed above D1, and the liquid phase discharge outlet was placed below D3. A gas phase channel D4 was provided in D2, and a heating coil D5 was provided between D2 and D3.
The gas phase discharge port of the reactive distillation column 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 positioned above D1 through a pipeline.
The charging bucket A is a raw material storage device and is used for storing raw materials for reaction, the A is connected with a feed pump B through a pipeline, the B is connected with a raw material heater C through a pipeline, and the C is connected with a feed inlet of a reaction rectifying tower D through a pipeline.
The mixed liquid of 2-phenyl-2-propanol and cumene (hereinafter also referred to as "reaction liquid") is stored in a charging bucket A, sent to a raw material heater C through a feeding pump B, heated to a temperature suitable for reaction, and sent to a reaction rectifying tower D through a feeding hole. After passing through the first catalyst layer D2, the reaction solution was appropriately heated by the heating coil D5 and then passed through the second catalyst layer D3.
And after a reaction product passes through a separation filler layer D1, an azeotrope (gas phase) of water and cumene is discharged from a gas phase discharge port at the top of the D and is sent to a condenser E, the condensed product is sent to a phase separator F, the oil-phase cumene 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 product is refluxed and enters a reaction rectifying tower D.
The liquid phase in the reaction product is discharged from the bottom of the reactive distillation column, and is a mixture of cumene and AMS.
In the embodiment of the invention, liquid distributors can be arranged between D1 and D2 and between D2 and D3.
Fig. 2 illustrates another embodiment of the process and apparatus of the present invention. In the reactive distillation column D, a dehydration catalyst layer D4 was provided in one stage, and a separation packing layer D1 was provided above D4. The feed inlet was placed below D4, the gas phase discharge outlet was placed above D1, and the liquid phase discharge outlet was placed above D4.
The gas phase discharge port of the reactive distillation column 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 charging bucket A is used for storing raw materials for reaction, the A is connected with a feed pump B through a pipeline, the B is connected with a raw material heater C through a pipeline, and the C is connected with a feed inlet of a reaction rectifying tower D through a pipeline.
A mixed solution of 2-phenyl-2-propanol and cumene (hereinafter also referred to as a "reaction solution") is stored in a charging bucket A, is sent to a raw material heater C through a feeding pump B, is heated to a temperature suitable for reaction, and is sent to a reaction rectifying tower D through a feeding hole. The reaction solution passed through the catalyst layer D4 to undergo dehydration reaction.
And after a reaction product passes through a separation packing layer D1, discharging an azeotrope of water and cumene from a gas phase discharge port at the top of the D, sending the azeotrope to a condenser E, condensing the azeotrope, sending the condensed azeotrope to a phase separator F, separating the condensed azeotrope into oil-phase cumene and a water phase in the phase separator F, discharging the water phase to a wastewater treatment device, sending the oil phase to a reflux heater H through a reflux pump G, heating the oil phase, and refluxing the oil phase to enter a reaction rectifying tower.
The liquid phase in the reaction product was withdrawn from above D4 as a mixture of cumene and AMS.
In the embodiment of the invention, a liquid distributor can be arranged between D1 and D4.
The two processes and apparatuses shown in fig. 1 and 2 can achieve the desired effect, wherein the process and apparatus represented by fig. 2 have higher practicability and simpler equipment than those of fig. 1.
Example 1:
a reaction apparatus was set up according to the process flow and apparatus sequence of FIG. 1, wherein: the diameter of the reactive distillation column D is 0.5m, the total height is 3.3m, the catalyst layer in the reactive distillation column is divided into two sections, namely a first catalyst layer D2 and a second catalyst layer D3, each section is 0.5m, and a gas phase channel DN100 is reserved in the first catalyst layer D2. The separating filler layer D1 above D2 in the upper part of the reactive distillation column was packed with MELPACK 252 packing of 0.6m height. Liquid distributors are arranged in the reactive distillation column between D1 and D2 and between D2 and D3, and the design of the liquid distributors is the same as that of a conventional column. The adopted catalyst is spherical, and the main component is gamma-A1 2 O 3 The diameter is 4-8 mm, and the bulk density is about 0.7 g/mL. The raw material heater C and the reflux heater H are both tube-type heat exchangers, and the heat exchange area of C is 0.66m 2 H heat exchange area 0.52m 2 . The heating coil D5 at the middle part of the reactive distillation tower 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; the feed pump B and the reflux pump G are metering pumps, and the flow range is 50-200L/h; bucket A has a volume of 200L.
Safety check of the whole device 2 After purging and replacement, firstly cumene containing 10 percent of moisture is added into the system, and the temperature is raised through a raw material heat exchanger C and a reflux heater H, so that the temperature in the reactive distillation tower is raised to 160-165 ℃, and the pressure is controlled at 0.2 MPa. Then according to the liquid hourly space velocity of 0.5h -1 To the reactive distillation column, a cumene solution of 50% DMBA (hereinafter also referred to as "reaction liquid") was added. The feed temperature was controlled at 160 ℃ and the reflux temperature at 125 ℃ by controlling the flow rate 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 the heating coil D5, and then enters the second-stage catalystThe catalyst layer D3, the tower bottom discharge temperature 153 ℃. And (4) sampling and analyzing the DMBA content from the discharged material at the bottom of the tower. The change in concentration of DMBA, AMS and impurities was determined by gas chromatography. The conversion was calculated from the change in the area of the peak 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 impurity. The conversion rate of DMBA is 98.2 percent through measurement and analysis. The AMS selectivity was greater than 99.6%.
Example 2:
the feed flow is adjusted to ensure that the liquid hourly space velocity is 0.4h -1 Otherwise, samples were taken from the bottom of the column under the same conditions as in example 1 for the DMBA content. The analysis revealed that the conversion of DMBA was 99.1%. The AMS selectivity was greater than 99.6%.
Example 3:
the feed flow is adjusted to ensure that the liquid hourly space velocity is 0.6h -1 Otherwise, samples were taken from the bottom of the column under the same conditions as in example 1 for the DMBA content. The analysis showed that the conversion of DMBA was 97.3%. The AMS selectivity was greater than 99.6%.
Example 4:
the feed flow is adjusted to ensure that the liquid hourly space velocity is 0.8h -1 Otherwise, samples were taken from the bottom of the column under the same conditions as in example 1 for the DMBA content. The analysis revealed that the conversion of DMBA was 92.8%. The AMS selectivity was greater than 99.6%.
Example 5:
the apparatus and conditions of example 1 were as described except that the temperature in the reactive distillation column was raised to 185 ℃ by the feed heat exchanger C and the reflux heater H, and the pressure was controlled to 0.25 MPa. Then according to the liquid hourly space velocity of 0.6h -1 Adding 50 percent of DMBA cumene solution into the reaction rectifying tower at the speed of (1). The feeding temperature is controlled to be 180 ℃ by controlling the flow rate of steam, and the reflux temperature is controlled to be 130 ℃. After the reaction liquid passes through a section of catalyst layer D2, the temperature is reduced from 180 ℃ to about 169 ℃ without opening a heating coil D5, and the discharging temperature of the tower bottom is 163 ℃. And (4) sampling and analyzing the DMBA content from the discharged material at the bottom of the tower. The analysis revealed that the conversion of DMBA was 99.3%. The AMS selectivity was greater than 99.4%.
Example 6:
the process flow according to FIG. 2 andthe device sequentially builds a reaction device, wherein: the diameter of the reactive distillation column D is 0.5m, the total height is 3.3m, and the height of the catalyst layer D4 in the separation column is 1.2 m. The separating filler layer D1 above D4 in the upper part of the reactive distillation column was packed with MELPACK 252 packing of 0.6m height. A liquid distributor is arranged between D1 and D4 in the reactive distillation column, and the design of the liquid distributor is the same as that of a conventional column. The adopted catalyst is spherical, and the main component is gamma-A1 2 O 3 The diameter is 4-8 mm, and the bulk density is about 0.7 g/mL. The raw material heater C and the reflux heater H are both tube-type heat exchangers, and the heat exchange area of C is 0.66m 2 H heat exchange area 0.52m 2 . Phase separator F volume 15L, aspect ratio 2: 1; the feed pump B and the reflux pump G are metering pumps, and the flow range is 50-200L/h; bucket A has a volume of 200L.
Safety check of the whole device 2 After purging and replacement, cumene containing 10 percent of moisture is added into the system, and the temperature is raised through a raw material heat exchanger C and a reflux heater H, so that the temperature in the reactive distillation column reaches 180 ℃ and 185 ℃, and the pressure is controlled at 0.25 MPa. Then according to the liquid hourly space velocity of 0.6h -1 Adding 50 percent of DMBA cumene solution into the reaction rectifying tower at the speed of (1). The feeding temperature is controlled to be 180 ℃ by controlling the flow rate of steam, and the reflux temperature is controlled to be 130 ℃. After the reaction solution passed through the catalyst layer D4, the temperature was decreased from 180 ℃ to about 162 ℃. And (3) extracting a product material from the upper part of the catalyst layer D4 through the liquid level control in the tower, and sampling to analyze the content of DMBA. The analysis revealed that the conversion of DMBA was 99.6%. The AMS selectivity was greater than 99.6%.
Example 7
The apparatus and conditions of example 6 were as described except that the temperature in the reactive distillation column was raised to 175 ℃ by the feed heat exchanger C and the reflux heater H, and the pressure was controlled to 0.2 MPa. Then according to the liquid hourly space velocity of 0.6h -1 Adding 50 percent of DMBA cumene solution into the reaction rectifying tower at the speed of (1). The feeding temperature is controlled to be 170 ℃ by controlling the flow of steam, and the reflux temperature is controlled to be 125 ℃. After the reaction liquid passes through the catalyst D4, the temperature is reduced from 170 ℃ to about 153 ℃. Through the liquid level control in the tower, product materials are extracted from the upper part of the catalyst layer D4, and the DMBA content is analyzed by sampling. The analysis revealed that the conversion of DMBA was 98.5%. AMS selectivity greater than 99.5％。
Example 8
The apparatus and conditions of example 7 were followed except that the height of the separation packing layer was reduced from 0.6m to 0.4 m. And (3) after 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 conversion of DMBA was 98.6% and the AMS selectivity was greater than 99.5%.
Example 9
The apparatus and conditions of example 1 were followed except that the height of the separation packing layer was increased from 0.6m to 1m, and the reaction conditions were kept the same as those of example 1. After the dehydration reaction and separation, the material discharged from the tower bottom is sampled and analyzed to obtain the DMBA content: the conversion of DMBA was 98.3% and the AMS selectivity was greater than 99.5%.
Example 10
The equipment set-up and conditions of example 6 were followed except that the height of the packing layer was decreased from 0.6m to 0.4m and the height of the catalyst layer D4 was increased from 1.2m to 1.8m, and the reaction conditions were kept the same as in example 6. And (3) after 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 conversion of DMBA was 99.7% and the 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, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (11)

1. A method for preparing alpha-methyl styrene 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, 2-phenyl-2-propanol is subjected to dehydration reaction in the reaction rectifying device in the presence of a catalyst for catalyzing dehydration reaction, the isopropylbenzene and water generated by the dehydration reaction are discharged from the reaction rectifying device in a gas phase form, and the generated alpha-methyl styrene is discharged from the reaction rectifying device in a liquid phase form;
preferably, the mass fraction of the 2-phenyl-2-propanol in the mixed solution of the 2-phenyl-2-propanol and the cumene is 10 to 80 percent, and preferably 30 to 60 percent.
2. The method according to claim 1, wherein the dehydration reaction temperature is 120-;
preferably, the dehydration reaction pressure is 0.1-0.4MPa, preferably 0.15-0.3 MPa;
preferably, the feeding amount is controlled at the liquid hourly space velocity of 0.2-2.0h -1 Preferably 0.3 to 1.0h -1 。
3. The method according to claim 1 or 2, wherein a separation packing layer and a catalyst layer are arranged in the reactive distillation device from top to bottom in sequence;
preferably, the reactive distillation device is a reactive distillation tower, and the height-diameter ratio of the reactive distillation tower is 5: 1-10: 1;
preferably, the height-diameter ratio of the separation packing layer is 0.8: 1-2: 1;
preferably, the height-diameter ratio of the catalyst layer is 1.9: 1-4: 1;
preferably, the catalyst layer is one segment;
preferably, the catalyst layer is two or more in number.
4. The method according to any one of claims 1 to 3, wherein the mixture of 2-phenyl-2-propanol and cumene is introduced into the reaction-rectification apparatus from the middle part thereof and flows downward in the apparatus through a catalyst layer disposed below the feed position; discharging the generated alpha-methyl styrene from the lower part of the reaction rectification device in a liquid phase form; the cumene and the generated water upwards pass through a separation packing layer and are discharged from the top of the reaction rectifying device in a gas phase form;
preferably, the mixed liquid is heated when the temperature of the mixed liquid is lowered to a temperature unsuitable for the dehydration reaction after flowing down through the catalyst layer;
preferably, the catalyst layer is two or more than two sections which are distributed at intervals;
preferably, a gas phase passage is provided in the catalyst layer other than the lowermost stage so as to allow cumene and water in the gas phase to rise; preferably, in the catalyst layer with the gas-phase channels, one or more gas-phase channels are 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 tower, preferably 2% -10% of the internal cross-sectional area of the reactive distillation tower;
preferably, a liquid distribution member is provided between the separation packing layer and the catalyst layer, and/or between the catalyst layers in each stage, to uniformly distribute the liquid material.
5. The method according to any one of claims 1 to 3, wherein the mixture of 2-phenyl-2-propanol and cumene is introduced into the apparatus from the lower part of the reactive distillation apparatus and flows upward in the apparatus through the catalyst layer disposed above the feed position; discharging the generated alpha-methyl styrene from the middle part of the reaction rectifying device in a liquid phase form; the cumene and the generated water upwards pass through a separation packing layer and are discharged from the top of the reaction rectifying device in a gas phase form;
preferably, the catalyst layer is one segment.
6. The process according to any one of claims 1 to 5, characterized in that water and cumene are discharged from the reactive distillation unit as an azeotrope;
preferably, the azeotrope is condensed to a liquid state to form a condensate;
preferably, the condensate is subjected to phase separation treatment and is divided into an oil phase and a water phase;
preferably, the separated cumene enters the reaction rectifying device again for reflux;
preferably, refluxing cumene enters the reaction rectifying device from the upper part of the separation packing layer;
preferably, the refluxed cumene is subjected to a heating treatment and then enters the reactive distillation device, and the refluxed cumene is heated to 140 ℃ of 100 ℃, preferably to 135 ℃.
7. The process according to any one of claims 1 to 6, wherein the heated aqueous cumene is used to raise the temperature in the reactive distillation apparatus to the dehydration reaction temperature before feeding the mixture of 2-phenyl-2-propanol and cumene;
preferably, the water content of the hydrous cumene is 5-15%.
8. A production apparatus for use in the method according to any one of claims 1 to 7, wherein the apparatus comprises a reactive distillation apparatus, a condensation apparatus, a phase separation apparatus; a dehydration catalyst layer is arranged in the reaction rectification device, and a separation packing layer is arranged above the dehydration catalyst layer; a feed inlet of the reaction rectifying device is arranged below the separation packing layer, and a gas phase discharge outlet is arranged above the separation packing layer of the reaction rectifying device; the condensing device is connected with a gas-phase discharge port of the reaction rectifying device through a pipeline; the phase separation device is connected with the condensing device through a pipeline;
preferably, the reactive distillation device is a reactive distillation tower, and the height-diameter ratio of the reactive distillation tower is 5: 1-10: 1;
preferably, the height-diameter ratio of the separation packing layer is 0.8: 1-2: 1;
preferably, the height-diameter ratio of the dehydration catalyst layer is 2: 1-4: 1;
preferably, the dehydration catalyst layer is one-stage;
preferably, the dehydration catalyst layer is two or more stages.
9. The production apparatus according to claim 8, wherein the dehydration catalyst layer is provided in a multi-stage arrangement, a feed port is provided above the uppermost catalyst layer, and a liquid-phase discharge port is provided below the lowermost catalyst layer;
preferably, a heating member is installed between every two adjacent catalyst layers;
preferably, gas phase channels are distributed in the catalyst layer outside the lowest section, one or more gas phase channels are arranged in the catalyst layer with the gas phase channels, 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, and the gas phase channels are preferably 2% -10% of the internal cross sectional area of the reactive distillation column;
preferably, the dehydration catalyst layer is in a two-stage arrangement form; 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; between two catalyst layers; a heating component is arranged; gas phase channels are distributed in the upper catalyst layer, the number of the gas phase channels is one or more, 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, and preferably 2% -10% of the internal cross-sectional area of the reactive distillation column.
10. The production apparatus according to claim 8, wherein the dehydration catalyst layer is provided in a single stage, the feed port is provided below the catalyst layer, and the liquid phase discharge port is provided between the separation packing layer and the catalyst layer.
11. The production apparatus according to any one of claims 8 to 10, further comprising a device for heating reflux cumene, wherein the heating device is connected to an oil phase discharge port of the phase separation device through a pipeline;
preferably, a discharge hole of the heating device for refluxing the cumene is connected with a reflux material feed inlet of the reaction rectifying device through a pipeline, and the reflux material feed inlet is arranged above the separation packing layer;
preferably, the water phase discharge port of the phase separation device is connected with a device for storing or treating waste water through a pipeline;
preferably, a liquid distribution component is arranged between the separation filler layer and the catalyst layer and/or between each section of the catalyst layer;
preferably, the production device further comprises a raw material heating device, and the raw material heating device is connected with a feeding hole of the reaction rectifying device through a pipeline;
preferably, the production device further comprises a raw material storage device, and the raw material storage device is connected with the raw material heating device through a pipeline.
CN202210689139.6A 2022-06-16 2022-06-16 Method and device for preparing alpha-methylstyrene by dehydrating 2-phenyl-2-propanol Active CN114874066B (en)

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