An apparatus and method for producing cyclohexane dimethylate

Abstract

The application relates to a preparation production device and a production method for 1,4-cyclohexane dicarboxylate, in particular to a method for continuously preparing cyclohexane dicarboxylate by adopting terephthalate as raw material and adopting two-stage reactors. The method has the advantages of low operation energy consumption, relatively mild reaction condition, stable product performance, hydrogenation reaction conversion rate close to 100%, residual amount of phthalate less than 50 ppm, product selectivity greater than 99.5%, and product purity reaching more than 99.5%.

Description

TECHNICAL FIELD

[0001] The present application relates to a production device and a production method of cyclohexane dicarboxylic acid ester, in particular, a method for preparing cyclohexane dicarboxylic acid ester by using terephthalate as raw material and using two-stage fixed bed reactor for continuous production. BACKGROUND

[0002] Phthalate esters (PAEs) are a kind of plasticizers widely used in production, which can enter the human body through various channels, and its toxicity research has been widely concerned by scholars. Cyclohexane dicarboxylic acid ester prepared by catalytic hydrogenation of PAEs not only has similar structure and performance to PAEs, but also is environmentally friendly, non-toxic and harmless, which conforms to the concept of green chemical development.

[0003] There are many studies on PAEs hydrogenation at home and abroad. For example, Chinese patent CN101406840A discloses a preparation method of cyclohexane dicarboxylic acid diester, which selects noble metals Ru, Pt, Pd and Rh as main active components, Fe, Co, Ni and Cu as additives, and aluminum oxide, zirconium oxide or titanium oxide as carrier to prepare a hydrogenation catalyst. The hydrogenation reaction of DINP is carried out in a trickle bed high-pressure reactor under the conditions of temperature 200℃, hydrogen pressure 7.0MPa, space velocity 0.5h –1 -1, and molar ratio of hydrogen to reaction substrate 150, and the conversion rate can reach 99.9% and the selectivity 98.6%.

[0004] Chinese patent CN108940305A discloses a hydrogenation catalyst and a preparation method of cyclohexane dicarboxylic acid diester. One or more than two of rhodium, ruthenium and palladium are used as active components, Cu and / or Ag are used as additive elements, and activated carbon and / or alumina are used as carriers to prepare a hydrogenation catalyst. The content of the active element is 0.1-8w%, preferably 0.3-6w%, and the content of the additive element is 0.1-4w%, preferably 0.2-2w%. A fixed bed reactor is used, the space velocity is 0.5-3h-1, the temperature is 80-160℃, and the reaction pressure is 0.5-7MPa. The conversion rate is 99.7%, and the highest selectivity can only reach 98.2%. The cost of noble metal used is high, and 1.8% of by-products are produced.

[0005] Chinese patent CN103240101A discloses a preparation method of phthalic acid diester hydrogenation catalyst, which uses an alumina-silica mixture carrier, the active component is noble metal Ru or / and Pd, and a transition metal Ni additive is added in the carrier forming stage. The conversion rate and selectivity of the reactant both reach more than 99%.

[0006] Chinese patent CN102658182 A discloses a catalyst for hydrogenation conversion of phthalate plasticizers into cyclohexane dicarboxylate plasticizers, its preparation method and application. The catalyst is composed of active ingredient, auxiliary agent and carrier, wherein the mass percentage of the active ingredient is 15-35%, the mass percentage of the auxiliary agent is 0.5-10%, and the rest is the carrier; the active ingredient is oxide of transition metal Ni, and the auxiliary agent is P. The conversion rate is 99.7%, and the selectivity is 99.75%.

[0007] Zhao Kaijing et al. carried out catalytic hydrogenation of DOP on a fixed bed with a Ni-based catalyst, and a series of process conditions were optimized. The best process conditions are: pressure 8 MPa, temperature 180℃, space velocity 0.5h -1 , and the product selectivity of the catalyst is always above 99% in 50h test time. Luo Junwen catalyzed DBP by Ni / Al2O3, and the conversion rate of DBP was 99.9%, and the selectivity of product CDADE was 92.5%. The experiment requires high temperature and high pressure, and the conversion rate of raw materials is very high, but the product selectivity is not good.

[0008] Whether using noble metal or nickel-based hydrogenation catalyst, the residual amount of phthalate plasticizers is relatively high, and at the same time, since part of the phthalate plasticizers is a mixture, the product is not easy to separate by distillation method, so it is of great significance to reduce the content of phthalate in cyclohexane dicarboxylate to meet the limited standard. SUMMARY

[0009] The technical problem to be solved by the present application is to overcome the technical deficiency of high content of phthalate in cyclohexane dicarboxylate, and to provide a preparation equipment and method which is simple in process and can realize continuous production, has low energy consumption, relatively mild reaction conditions, stable product performance, hydrogenation conversion rate close to 100%, residual amount of phthalate less than 50ppm, product selectivity greater than 99.5%, and product purity above 99.5%.

[0010] In order to achieve the above purpose, the first aspect of the present application provides a production equipment of cyclohexane dicarboxylate, comprising:

[0011] A first liquid feeding device for providing phthalate liquid to the equipment;

[0012] A first gas feeding device for providing hydrogen to the equipment;

[0013] a first reactor connected with a first liquid feeding device and a second gas feeding device, for receiving phthalate liquid from the first liquid feeding device and hydrogen from the second gas feeding device, and configured to react the phthalate liquid and hydrogen to produce a mixture containing cyclohexane dimethylate;

[0014] a first gas-liquid separation device connected with the bottom of the first reactor, for receiving reaction products from the first reactor and carrying out gas-liquid separation; the gas-liquid separation device is also connected with the top of the first reactor through another pipeline, for returning hydrogen obtained after gas-liquid separation to the first reactor for recycling;

[0015] a second reactor connected with the gas-liquid separation device through a second liquid feeding device, for receiving crude cyclohexane dimethylate product processed from the gas-liquid separation device; the second reactor is also connected with a second gas feeding device, for receiving hydrogen from the second gas feeding device; the second reactor is filled with a ruthenium-based catalyst and configured to further react the crude cyclohexane dimethylate product with hydrogen to produce a mixture containing cyclohexane dimethylate;

[0016] a second gas-liquid separation device connected with the second reactor, for receiving the mixture containing cyclohexane dimethylate from the second reactor and carrying out gas-liquid separation, thereby obtaining final product cyclohexane dimethylate.

[0017] In a preferred embodiment of the present application, the first reactor is a column reactor.

[0018] In a preferred embodiment of the present application, the second reactor is a tower fixed bed reactor.

[0019] In a preferred embodiment of the present application, the outlet of the first liquid feeding device is in airtight communication with the feeding port at the top of the first reactor.

[0020] In a preferred embodiment of the present application, the outlet of the second liquid feeding device is in airtight communication with the feeding port at the bottom of the second reactor.

[0021] Specifically, in a specific embodiment of the present application, the device includes two sets of liquid feeding devices, two sets of gas feeding devices, a column fixed bed reactor, a tower fixed bed reactor and two sets of gas-liquid separation systems (see Figure 1). The top end of the fixed tube reactor (5) is provided with a material inlet, and the jacket is used to heat and cool the material by circulating heat conducting oil or condensed water-steam. The first liquid feeding device comprises a raw material tank (1), a feeding pump group (2), a mass flow controller, a preheater (3) and a feeding pipeline; the material outlet of the feeding pipeline is in sealed communication with the feeding port at the top of the fixed tube reactor (1). The second liquid feeding device comprises a feeding pump group (8), a mass flow controller, a preheater (9) and a feeding pipeline; the material outlet of the feeding pipeline is in sealed communication with the feeding port at the bottom of the tower type fixed bed reactor (10). The first gas feeding device comprises a fresh hydrogen gas inlet pipe for providing fresh hydrogen gas to the fixed tube reactor (5) and a hydrogen gas recycling device for collecting and providing recycled hydrogen gas to the fixed tube reactor (5), which comprises a fresh hydrogen gas inlet pipe provided with a control valve and a mass flow controller, a nitrogen gas inlet pipe provided with a control valve and the hydrogen gas recycling device; the hydrogen gas recycling device comprises a hydrogen gas recycling compressor (4) and two inlet and outlet buffer tanks, and the gas outlet of the inlet pipeline is in sealed communication with the gas feeding port of the fixed tube reactor (5). The second gas feeding device comprises a fresh hydrogen gas inlet pipe for providing fresh hydrogen gas to the tower type fixed bed reactor (10), which comprises a fresh hydrogen gas inlet pipe provided with a control valve and a mass flow controller, a nitrogen gas inlet pipe provided with a control valve, and the gas outlet of the inlet pipeline is in sealed communication with the gas feeding port of the fixed tube reactor (10). The first gas-liquid separation device comprises a heat exchanger (6), a separation tank (7) and a gas venting pipeline; the inlet of the gas-liquid mixed feed is in sealed communication with the outlet of the reactor (5), the liquid outlet of the separation tank (7) is in sealed communication with the inlet of the feeding pump (8), and the gas outlet is in sealed communication with the inlet of the hydrogen gas recycling compressor (4) and the venting pipe. The second gas-liquid separation device comprises a heat exchanger (11), a separation tank (12), a gas venting back pressure valve (14) and a connecting pipeline; the inlet of the gas-liquid mixed feed is in sealed communication with the outlet of the reactor (10), the liquid outlet of the separation tank (12) is in sealed communication with the inlet of the product storage tank (13), and the gas outlet is in sealed communication with the back pressure valve (14) pipe.

[0022] The second aspect of the present application provides a method for producing cyclohexane dicarboxylate using the device of the present application, comprising:

[0023] 1) introducing the phthalate liquid in the first liquid feeding device into the first reactor, while hydrogen gas enters the first reactor through the first gas feeding device, in the first reactor, the hydrogen gas and the phthalate are in sufficient contact, and the hydrogenation reaction is carried out under the action of the nickel-based hydrogenation catalyst, the molar ratio of hydrogen gas to ester is 4-8:1, and a mixture containing crude cyclohexane dicarboxylate is prepared;

[0024] 2) the mixture containing crude cyclohexane dimethylate from the first reactor is introduced into a first gas-liquid separation device, the separated hydrogen is partly recycled to the first reactor for continuous use after compression, and the other part is discharged to a tail gas vent to maintain system balance; the crude cyclohexane dimethylate separated by the gas-liquid separation device is introduced into a second reactor (10) through a second liquid feed device, and fresh hydrogen is introduced into the second reactor through a second gas feed device, the hydrogen and the crude cyclohexane dimethylate are fully contacted in the tower type fixed bed reactor (10), and a hydrogenation reaction is carried out under the action of a ruthenium-based hydrogenation catalyst to prepare a cyclohexane dimethylate mixture, and the mixture is separated by a second gas-liquid separation device to obtain the final product cyclohexane dimethylate.

[0025] In some preferred embodiments of the present application, the nickel-based hydrogenation catalyst used in the first reactor has a composition of 18-30% by weight of nickel and the rest is carrier alumina.

[0026] In some preferred embodiments of the present application, the ruthenium-based catalyst loaded in the second reactor has a composition of 0.2-0.6% by mass of ruthenium and the rest is carrier alumina.

[0027] In some preferred embodiments of the present application, the phthalate ester is selected from dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate or diisononyl phthalate.

[0028] In some preferred embodiments of the present application, the hydrogenation reaction in the first reactor has a temperature of 90-200°C, a pressure of 3-5 MPa, and a liquid volume space velocity of 1-2 h -1 ; the hydrogenation reaction in the second reactor has a temperature of 90-150°C, a pressure of 4-6 MPa, and a liquid volume space velocity of 2-3 h -1 .

[0029] According to a specific embodiment of the present application, the method for preparing cyclohexane dimethylate by catalytic hydrogenation of phthalate ester specifically comprises the following steps:

[0030] a) open the upper end cover of the tubular fixed bed reactor (5), load the nickel-based catalyst into the tubes, cover the upper end cover after the loading is completed, and then check the air tightness of the reaction system.

[0031] b) open the upper end cover of the tower type fixed bed reactor (10), load the ruthenium-based catalyst into the reactor, cover the upper end cover after the loading is completed, and then check the air tightness of the reaction system.

[0032] c) After passing the phthalate liquid in the raw material kettle through the metering pump (2) to meter and pressurize, through the preheater (3) to preheat, and then into the top of the fixed bed reactor (5), while hydrogen is pressurized through the hydrogen circulation compressor (4) and mixed with fresh hydrogen to enter the top of the fixed bed reactor (5), the hydrogen and phthalate are fully contacted in the fixed bed reactor (5), and the hydrogenation reaction is carried out under the action of the supported nickel-based hydrogenation catalyst, the temperature of the hydrogenation reaction is 90-200 DEG C, the pressure is 3-5 MPa, the liquid volume space velocity is 1-2 h -1 -1, and the molar ratio of hydrogen to ester is 4-8:1, to obtain a mixture containing cyclohexane dimethylate; the mixture containing cyclohexane dimethylate obtained from the bottom of the fixed bed reactor (5) is exchanged in the heat exchanger (6) to make the temperature of the mixture 50-80 DEG C, and then enters the gas-liquid separation tank (7) to carry out gas-liquid separation, part of the hydrogen separated from the top of the gas-liquid separation tank is recycled after being compressed, and the other part is discharged to the tail gas vent to maintain system balance; the liquid cyclohexane dimethylate liquid separated from the gas-liquid separation tank (7) is metered and pressurized through the metering pump (8), preheated through the preheater (9), and then enters the bottom of the fixed bed reactor (10), while fresh hydrogen enters the bottom of the fixed bed reactor (10), the hydrogen and the crude cyclohexane dimethylate are fully contacted in the fixed bed reactor (10), and the hydrogenation reaction is carried out under the action of the supported ruthenium-based hydrogenation catalyst, the temperature of the hydrogenation reaction is 90-150 DEG C, the pressure is 4-6 MPa, and the liquid volume space velocity is 2-3 h -1 -1, to obtain a cyclohexane dimethylate mixture with low aromatic ring content, the mixture flows out from the top of the fixed bed reactor (10) and is exchanged in the heat exchanger (11) to make the temperature of the mixture 50-80 DEG C, and then enters the gas-liquid separation tank (12) to carry out gas-liquid separation, the hydrogen separated from the top of the gas-liquid separation tank is discharged to the tail gas vent through the back pressure valve (14) to maintain stable system pressure.

[0033] In the present application, the fixed bed reactor is internally provided with heating coils below, and the heating medium in the coils is heat-conducting oil or water vapor.

[0034] The present application has the following beneficial technical effects:

[0035] (1) The present application uses a two-stage hydrogenation process, the first stage uses a fixed bed reactor in the form of a tube bundle, and the hydrogen is circulated, so that the heat generated in the hydrogenation reaction process can be quickly conducted out by using the heat-conducting medium in the shell side and the circulating hydrogen, thereby avoiding the reaction heat in the hydrogenation process from being dispersed and removed too slowly, which leads to a large temperature rise, on the one hand, the high temperature can cause the catalyst to sinter, reducing the service life of the catalyst, on the other hand, the high temperature can cause the side reactions to intensify, reducing the selectivity of the product. Meanwhile, the heat removed can be recycled, realizing comprehensive recycling of heat, which is more economical and environmentally friendly.

[0036] (2) The first stage hydrogenation of the present application adopts a supported nickel-based hydrogenation catalyst, which can reduce the operating cost of the catalyst compared with the noble metal catalyst.

[0037] (3) The first stage hydrogenation of the present application adopts the feeding mode of phthalate raw material, which reduces the residence time of the material in the catalyst, improves the selectivity of the product, and thus achieves the purpose of improving the purity of the product.

[0038] (4) The second stage hydrogenation of the present application adopts a ruthenium-based catalyst with superior deep hydrogenation performance for benzene ring, which can improve the conversion rate of the raw material and make the residual amount of phthalate lower. Since the content of phthalate in the hydrogenation raw material is reduced, the reaction heat is less, and the tower fixed bed reactor and the lower feeding mode are adopted, the residence time of the material in the catalyst can be prolonged, and the reaction is more complete. On the one hand, the heat can be comprehensively utilized, and on the other hand, the conversion rate of the raw material phthalate can be improved.

[0039] (5) In the second stage hydrogenation process of the present application, hydrogen is continuously supplemented in the form of maintaining pressure, and hydrogen circulation is not used. On the one hand, since the reaction heat is less, hydrogen is not needed to carry heat, which reduces the operating energy consumption of the hydrogen circulation compressor. On the other hand, there is basically no hydrogen venting, which reduces the hydrogen consumption loss due to hydrogen venting in the reaction process.

[0040] (6) The product of the present application has stable performance, high conversion rate of hydrogenation reaction, low content of residual phthalate in the hydrogenation product (less than 50 ppm), high selectivity, and product purity of more than 99.5%. The product can be directly used as a plasticizer without separation.

[0041] (7) The present application adopts the two-stage hydrogenation mode of conventional nickel-based and ruthenium-based hydrogenation catalysts, which reduces the catalytic cost. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a continuous preparation process flow diagram of cyclohexane dicarboxylate.

[0043] The numbers in the figure are: 1 - raw material kettle; 2 - metering pump; 3 - preheater; 4 - hydrogen circulation compressor; 5 - tubular fixed bed reactor; 6 - heat exchanger; 7 - gas-liquid separation tank; 8 metering pump; 9 - preheater; 10 - tower fixed bed reactor; 11 - heat exchanger; 12 - gas-liquid separation tank; 13 - product storage tank; 14 - back pressure valve. DETAILED DESCRIPTION

[0044] The present application will be further described below with reference to the accompanying drawings.

[0045] In order to make the technical solutions and advantages of the present application clearer, the solutions in the present application are described clearly and completely below through examples.

[0046] The specific process and implementation operation process of the present application are further described below in combination with the drawings:

[0047] See Figure 1 The equipment for preparing cyclohexane dicarboxylic acid ester with low aromatic ring content comprises two sets of liquid feeding devices, two sets of gas feeding devices, a tubular fixed bed reactor, a tower fixed bed reactor and two sets of gas-liquid separation devices. The top end of the tubular fixed bed reactor (5) is provided with a material inlet, and circulating heat conduction oil or condensed water-steam is used to heat and cool the material in the jacket. The first liquid feeding device comprises a raw material tank (1), a feeding pump group (2), a mass flow controller, a preheater (3) and a feeding pipeline; the material outlet of the feeding pipeline is in sealed communication with the feeding port at the top of the tubular fixed bed reactor (1). The second liquid feeding device comprises a feeding pump group (8), a mass flow controller, a preheater (9) and a feeding pipeline;

[0048] The material outlet of the feeding pipeline of the first liquid feeding device is in sealed communication with the feeding port at the bottom of the tower fixed bed reactor (10). The first gas feeding device comprises a fresh hydrogen gas feeding pipeline for providing fresh hydrogen gas to the tubular fixed bed reactor (5) and a hydrogen gas recycling device for collecting and providing recycled hydrogen gas to the fixed bed reactor (5), which comprises a fresh hydrogen gas feeding pipeline provided with a control valve and a mass flow controller, a nitrogen gas feeding pipeline provided with a control valve and the hydrogen gas recycling device; the hydrogen gas recycling device comprises a hydrogen gas recycling compressor (4) and two buffer tanks at the inlet and outlet, and the gas outlet of the feeding pipeline is in sealed communication with the gas feeding port of the fixed bed reactor (5).

[0049] The second gas feeding device comprises a fresh hydrogen gas feeding pipeline for providing fresh hydrogen gas to the tower fixed bed reactor (10), which comprises a fresh hydrogen gas feeding pipeline provided with a control valve and a mass flow controller, a nitrogen gas feeding pipeline provided with a control valve, and the gas outlet of the feeding pipeline is in sealed communication with the gas feeding port of the fixed bed reactor (10).

[0050] The first gas-liquid separation device comprises a heat exchanger (6), a separation tank (7) and a gas venting pipeline; the mixed feeding inlet of the first gas-liquid separation device is in sealed communication with the outlet of the reactor (5), the liquid outlet of the separation tank (7) is in sealed communication with the inlet of the feeding pump (8), and the gas outlet is in sealed communication with the inlet of the hydrogen gas recycling compressor (4) and the venting pipeline.

[0051] The second gas-liquid separation device comprises a heat exchanger (11), a separation tank (12), a gas venting back pressure valve (14) and connecting pipelines. The gas-liquid mixed feed inlet of the second gas-liquid separation device is in closed communication with the outlet of the reactor (10), the liquid outlet of the separation tank (12) is in closed communication with the inlet of the product storage tank (13), and the gas outlet is in closed communication with the back pressure valve (14).

[0052] The low-aromatic ring content cyclohexane dicarboxylate preparation device uses the method for preparing cyclohexane dicarboxylate by catalytic hydrogenation of phthalate ester, and the specific implementation of the method comprises the following steps:

[0053] S1: catalyst loading and system displacement

[0054] Open the upper end cover of the fixed tube bed reactor (5), fix the grate plate paved with stainless steel mesh at the lower end of the tube, first load the porcelain balls with a height of about 200 mm at the lower part of the tube, load the pre-reduced supported nickel-based hydrogenation catalyst into the fixed tube bed reactor, and stop loading when the catalyst height is 300 mm away from the tube opening, then load the porcelain balls at the upper end of the tube opening, fix the upper end grate plate, load the upper end liquid distributor, and finally cover the upper end cover.

[0055] Open the upper end cover of the fixed tube bed reactor (5), fix the grate plate paved with stainless steel mesh at the lower end of the tube, first load the porcelain balls with a height of about 200 mm at the lower part of the tube, load the pre-reduced supported nickel-based hydrogenation catalyst into the fixed tube bed reactor, and stop loading when the catalyst height is 300 mm away from the tube opening, then load the porcelain balls at the upper end of the tube opening, fix the upper end grate plate, load the upper end liquid distributor, and finally cover the upper end cover.

[0056] Perform airtightness test by charging nitrogen to 8.0 MPa in the fixed tube bed reactor (5) and the tower type fixed bed reactor (10) respectively, and the pressure drop is lower than 0.4 MPa after 24 hours, and the airtightness test is qualified, then the whole system is displaced by nitrogen, and the displacement is qualified when the oxygen content in the system is lower than 0.5%.

[0057] S2: feed operation: the phthalate ester liquid in the raw material kettle is metered by the metering pump (2) after being pressurized, preheated by the preheater (3), and then enters the top of the fixed tube bed reactor (5), at the same time, hydrogen is pressurized by the hydrogen circulation compressor 4, mixed with fresh hydrogen, and enters the top of the fixed tube bed reactor (5), the hydrogen and the phthalate ester are in full contact in the fixed tube bed reactor (5), and the hydrogenation reaction is carried out under the action of the supported nickel-based hydrogenation catalyst, the temperature of the hydrogenation reaction is 90-200℃, the pressure is 3-5 MPa, the liquid volume space velocity is 1-2h -1, the molar ratio of hydrogen and ester is 4-8:1, the prepared cyclohexane dimethylate mixture flows out from the bottom of the fixed bed reactor (5), is heated by the heat exchanger (6) to make the temperature of the mixture 50-80°C, then enters the gas-liquid separation tank (7) to carry out gas-liquid separation, the hydrogen separated out from the top of the gas-liquid separation tank is partly recycled after compression, and the other part is discharged to the tail gas vent to maintain the system balance; the liquid cyclohexane dimethylate separated out from the gas-liquid separation tank (7) is metered by the metering pump (8) after pressurization, is preheated by the preheater (9), then enters the bottom of the fixed bed reactor (10), and fresh hydrogen enters the bottom of the fixed bed reactor (10), the hydrogen and the crude cyclohexane dimethylate are fully contacted in the fixed bed reactor (10), and hydrogenation reaction is carried out under the action of the supported ruthenium-based hydrogenation catalyst, the temperature of the hydrogenation reaction is 90-150°C, the pressure is 4-6 MPa, the volume space velocity is 2-3h -1 , the prepared cyclohexane dimethylate mixture flows out from the bottom of the fixed bed reactor (5), is heated by the heat exchanger (6) to make the temperature of the mixture 50-80°C, then enters the gas-liquid separation tank (7) to carry out gas-liquid separation, the hydrogen separated out from the top of the gas-liquid separation tank is partly recycled after compression, and the other part is discharged to the tail gas vent to maintain the system balance; the liquid cyclohexane dimethylate separated out from the gas-liquid separation tank (7) is metered by the metering pump (8) after pressurization, is preheated by the preheater (9), then enters the bottom of the fixed bed reactor (10), and fresh hydrogen enters the bottom of the fixed bed reactor (10), the hydrogen and the crude cyclohexane dimethylate are fully contacted in the fixed bed reactor (10), and hydrogenation reaction is carried out under the action of the supported ruthenium-based hydrogenation catalyst, the temperature of the hydrogenation reaction is 90-150°C, the pressure is 4-6 MPa, the volume space velocity is 2-3h

[0058] The system hydrogen circulation of the first stage hydrogenation: the hydrogenation and separation system qualified by the air tightness test and nitrogen replacement, the nitrogen in the fixed bed reactor (5) is discharged by opening the tail gas vent valve, the pressure is controlled to be 0.05-0.10 MPa, then the fresh hydrogen control valve of the first stage gas feeding device is opened, hydrogen is slowly introduced into the fixed bed reactor (5) through the hydrogen flow control valve, when the reaction pressure increases by 4-5 MPa, the hydrogen circulation compressor (4) is started to make the hydrogen circulation of the whole hydrogenation and separation system, the heat conduction oil system (or steam is introduced into the shell side) of the fixed bed reactor (5) is started to control the temperature of the fixed bed reactor (5) to be 80-150°C.

[0059] The system hydrogen separation circulation of the first stage hydrogenation: the hydrogen separated out from the top of the gas-liquid separation tank (7) is partly discharged into the inlet of the hydrogen circulation compressor (4), then is compressed by the hydrogen circulation compressor (4) and recycled, and the other part is discharged to the tail gas vent to maintain the system balance, the hydrogen volume concentration of the whole system is controlled to be not less than 90%.

[0060] The hydrogen system of the second stage hydrogenation system: hydrogen is controlled by a pressure reducing valve at a pressure of 4-6 MPa, then enters the catalyst bed at the bottom of the tower fixed bed reactor (10) to mix and react with the material, after the hydrogenated material is cooled in the heat exchanger (11), separation is carried out in the gas-liquid separator (12), the gas is discharged from the top of the separator to enter the gas back pressure valve to maintain the system pressure stable, and the liquid enters the product collection tank (13) from the bottom of the separator.

[0061] Examples 1-16

[0062] In order to further illustrate the present application, the following describes the two-stage hydrogenation reaction and gas-liquid separation using different raw materials such as dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), and diisononyl phthalate (DINP) according to the above-mentioned implementation method, and the product purity is analyzed by using a gas-liquid chromatograph analyzer. The specific implementation conditions and product analysis data are shown in Table 1.

[0063]

[0064] Although the present application has been described with reference to the preferred embodiments, various modifications can be made to the application and equivalents thereof without departing from the scope of the application. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A production apparatus for cyclohexane dicarboxylate, comprising: A first liquid feeding device is used to supply phthalate liquid to the device; A first gas feeding device is used to supply hydrogen to the device; A first reactor, which is connected to a first liquid feed device and a first gas feed device respectively, is used to receive phthalate liquid from the first feed device and hydrogen from the first gas feed device. The first reactor is configured to react the phthalate liquid and hydrogen to produce a mixture containing crude cyclohexanedicarboxylate product. A first gas-liquid separation device is connected to the bottom of a first reactor to receive reaction products from the first reactor and perform gas-liquid separation; the gas-liquid separation device is also connected to the top of the first reactor through another pipe to return the hydrogen obtained after gas-liquid separation to the first reactor for recycling. A second reactor, connected to a gas-liquid separator via a second liquid feeder, is used to receive crude cyclohexane dicarboxylate product processed by the gas-liquid separator; the second reactor is also connected to a second gas feeder to receive hydrogen gas from the second gas feeder; the second reactor is packed with a ruthenium-based catalyst and configured to further react the crude cyclohexane dicarboxylate product with hydrogen gas to obtain a cyclohexane dicarboxylate mixture; A second gas-liquid separation device is connected to the second reactor for receiving the cyclohexane dicarboxylate mixture from the second reactor and performing gas-liquid separation to obtain the final product cyclohexane dicarboxylate. The first reactor is a tubular reactor, and the second reactor is a tower-type fixed-bed reactor. The outlet of the first liquid feeding device is in sealed communication with the inlet at the top of the first reactor, and the outlet of the second liquid feeding device is in sealed communication with the inlet at the bottom of the second reactor.

2. A method for producing cyclohexane dicarboxylate using the apparatus according to claim 1, comprising: 1) Phthalate liquid from the first liquid feed device is introduced into the first reactor, while hydrogen gas enters the first reactor through the first gas feed device. In the first reactor, hydrogen gas and phthalate ester are fully contacted and undergo a hydrogenation reaction under the action of a nickel-based hydrogenation catalyst. The molar ratio of hydrogen gas to ester is 4-8:1, and a mixture containing crude cyclohexanedicarboxylate is obtained. The first reactor is a tubular reactor, and the phthalate liquid is introduced from the top of the tubular reactor. 2) The mixture containing crude cyclohexane dicarboxylate from the first reactor is introduced into the first gas-liquid separation device. Part of the separated hydrogen is compressed and recycled back to the first reactor for continued use, while the other part is discharged to the tail gas vent to maintain system balance. The crude cyclohexane dicarboxylate separated by the gas-liquid separation device enters the second reactor (10) through the second liquid feed device. At the same time, fresh hydrogen enters the second reactor through the second gas feed device. In the tower-type fixed bed reactor (10), the hydrogen and the crude cyclohexane dicarboxylate are fully contacted and undergo a hydrogenation reaction under the action of a ruthenium-based hydrogenation catalyst to obtain a cyclohexane dicarboxylate mixture. After the mixture is separated by the second gas-liquid separation device, the final product cyclohexane dicarboxylate is obtained. The second reactor is a tower-type fixed bed reactor, and the crude cyclohexane dicarboxylate is introduced from the bottom of the tower-type fixed bed reactor.

3. The method according to claim 2, wherein, The nickel-based hydrogenation catalyst used in the first reactor consists of 18-30% by weight nickel, with the remainder being alumina supported by a carrier.

4. The method according to claim 2, wherein, The ruthenium-based catalyst packed in the second reactor consists of 0.2-0.6% ruthenium by mass, with the remainder being alumina as a support.

5. The method according to any one of claims 2-4, wherein, The phthalate is selected from dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate or diisononyl phthalate.

6. The method according to any one of claims 2-4, wherein, The hydrogenation reaction in the first reactor is carried out at a temperature of 90–200 °C, a pressure of 3–5 MPa, and a liquid hourly space velocity of 1–2 h⁻¹. -1 The hydrogenation reaction in the second reactor is carried out at a temperature of 90–150 °C, a pressure of 4–6 MPa, and a liquid hourly space velocity of 2–3 h⁻¹. -1 .

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