TW202017895A - A method for preparing dimethyl 1,4-cyclohexanedicarboxylate - Google Patents

Abstract

The present invention provides a method for preparing dimethyl 1,4-cyclohexanedicarboxylate (DMCD), comprising: firstly providing a continuous reactor with a plurality of particles of Ru/Al2O3 catalyst with a particle size of 1.5 to 5.0 mm, and its packing density of the particles of Ru/Al2O3 catalyst is 0.4 to 0.7 g/cm3, wherein the degree of Ru dispersion of the particles of Ru/Al2O3 catalyst is 13% or higher than 13%,; and hydrogenating reactant solution containing dimethyl terephthalate (DMT) and DMCD in the continuous reactor under a condition of a pressure of 20 to 30 kg/cm2 to prepare the DMCD. The method of present invention could increase the conversion rate effectively, perform excellent catalytic activity in the hydrogenation process, and reduce the cost of sequential treatment, thereby enhancing the value of the industrial application.

Description

Preparation method of dimethyl 1,4-cyclohexanedicarboxylate

The invention relates to a method for preparing dimethyl 1,4-cyclohexanedicarboxylate, in particular to a method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reaction.

1,4-Cyclohexane dimethanol (CHDM) is a monomer widely used in the manufacture of condensation polymers and special polyesters, and dimethyl 1,4-cyclohexane dicarboxylate (DMCD) is the one used in the synthesis process The intermediate is of great importance for the synthesis of 1,4-cyclohexanedimethanol.

In general, the preparation of dimethyl 1,4-cyclohexanedicarboxylate starts with dimethyl terephthalate (DMT) and produces 1,4 by hydrogenating the benzene ring of dimethyl terephthalate -Dimethyl cyclohexanedicarboxylate; early palladium catalysts were used for the benzene ring hydrogenation catalysts, but the palladium catalysts needed to react at higher pressures and higher temperatures, and the reaction preparation process required The use of water or fatty alcohol as the reaction solvent makes the subsequent separation process cumbersome and increases the plant construction cost and the operating cost of the reaction. In addition, the palladium-based catalyst is prone to be poisoned by carbon monoxide as a by-product of the reaction and is not conducive to production.

Nowadays, the prior art discloses the use of ruthenium catalysts for benzene ring hydrogenation reaction, so that the benzene ring hydrogenation reaction can be operated under low pressure environment and overcome the problem of being susceptible to carbon monoxide poisoning. However, the current ruthenium catalysts are easily deactivated due to their The use of short aging affects the production yield of the process, and when the ruthenium catalyst is used in a continuous reaction, the operating pressure cannot be lower than 40 bar, which fails to effectively solve the problem of expensive process cost.

In view of this, it is necessary to propose a method suitable for low-pressure operation and capable of continuously preparing dimethyl 1,4-cyclohexanedicarboxylate to solve the problems in the conventional technology.

In order to solve the above problems, the present invention provides a preparation method of dimethyl 1,4-cyclohexanedicarboxylate, which includes: providing a complex Ru/Al ₂ O ₃ catalyst filled with a particle size of 1.5 to 5.0 mm A continuous reactor of particles, and the packing density of the complex Ru/Al ₂ O ₃ catalyst particles of the continuous reactor is 0.4 to 0.7 g/cm 2 (g/cm ³ ), wherein the complex Ru/Al ₂ The ruthenium metal dispersion of O ₃ catalyst particles is more than 13%; and in the continuous reactor, the reactant solution containing dimethyl terephthalate and hydrogen is 20 to 30 kg/cm 2 (kg/ cm ² ) under hydrogenation to produce dimethyl 1,4-cyclohexanedicarboxylate; where the solvent of the reactant solution consists of dimethyl 1,4-cyclohexanedicarboxylate , So that the dimethyl terephthalate is dissolved in the dimethyl 1,4-cyclohexanedicarboxylate.

In the preparation method of dimethyl 1,4-cyclohexanedicarboxylate of the present invention, by adjusting the filling method of plural Ru/Al ₂ O ₃ catalyst particles in a continuous reactor, the thermal energy of the reaction process It can be quickly dispersed, and dimethyl 1,4-cyclohexanedicarboxylate is used as the reaction solvent, so that dimethyl 1,4-cyclohexanedicarboxylate can be weighed from 20 to 30 kg/cm ² (kg/cm ² ) Continuous preparation under low pressure environment effectively improves conversion rate and optimizes production capacity. In addition, the process does not use additional reaction solvents, reducing the cost of post-processing, while reducing the harm to the environment, and it has the value of industrial application.

10‧‧‧ Dimethyl terephthalate storage tank

11‧‧‧ 1,4-Cyclohexanedicarboxylic acid dimethyl storage tank

12‧‧‧Mixing tank

13, 22‧‧‧ Pump

14‧‧‧ Fixed bed reactor

15‧‧‧Hydrogen storage tank

16‧‧‧Preheater

17‧‧‧Temperature Controller

21‧‧‧separating tank

Exemplary embodiments of the present invention will be described with reference to the accompanying drawings: FIG. 1 is a flow chart of an apparatus for preparing a first example of dimethyl 1,4-cyclohexanedicarboxylate; and FIG. 2 is a preparation of 1,4 -Equipment flow chart of the second embodiment of dimethyl cyclohexanedicarboxylate.

The following describes the implementation of the present invention by specific specific examples. Those skilled in the art can easily understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied by other different embodiments. The details in this specification can also be based on different viewpoints and applications, and different modifications and changes can be given without departing from the spirit of the present invention. In addition, all ranges and values herein are inclusive and combinable. Any value or point that falls within the range described herein, for example, any integer can be used as the minimum or maximum value to derive the lower range.

According to the present invention, a method for preparing dimethyl 1,4-cyclohexanedicarboxylate includes: providing a continuous reaction filled with a plurality of Ru/Al ₂ O ₃ catalyst particles having a particle size of 1.5 to 5.0 mm And the packing density of the plural Ru/Al ₂ O ₃ catalyst particles of the continuous reactor is 0.4 to 0.7 g/cm 2 (g/cm ³ ), wherein the plural Ru/Al ₂ O ₃ catalyst particles The ruthenium metal dispersion is above 13%; and in the continuous reactor, the pressure of the reactant solution containing dimethyl terephthalate and hydrogen is 20 to 30 kg/cm ² (kg/cm ² ) The hydrogenation reaction is carried out to prepare dimethyl 1,4-cyclohexanedicarboxylate; wherein the solvent of the reactant solution is composed of dimethyl 1,4-cyclohexanedicarboxylate to make the pair Dimethyl phthalate is dissolved in the dimethyl 1,4-cyclohexanedicarboxylate.

The continuous reactor is a continuous feeding, continuous reaction and continuous discharging reaction mode. The continuous reactor includes a fixed bed reactor, a moving bed reactor or a fluidized bed reactor . In the embodiment of the present invention, the continuous reactor is particularly preferably a fixed bed reactor.

The fixed bed reactor, also known as a packed bed reactor, is a reactor filled with solid catalysts or solid reactants to achieve a multi-phase reaction process. In a fixed bed reactor, there is a pile of solids The bed is fixed when the reaction is in progress, allowing the fluid to react through the bed. The characteristic of this device is that the catalyst wear is small, and a small amount of catalyst can be used to obtain a larger output, which is beneficial to achieve High selectivity and conversion rate.

In the present invention, the fixed bed reactor can be selected according to the actual heat transfer requirements and the flow direction of the reaction flow, such as: trickle bed reactor, adiabatic fixed bed reactor, heat exchange fixed bed reactor, shaft The flow-to-flow fixed-bed reactor or the radial-flow fixed-bed reactor, but not limited to the above, is hereby described.

The filling method of the fixed bed reactor mentioned above may include granular, mesh, honeycomb or fibrous.

In a specific embodiment, the continuous reactor contains a plurality of inert particles. In this embodiment, the fixed-bed reactor is filled with mixed Ru/Al ₂ O ₃ catalyst particles and plural inert particles, and the mixed process of the mixed inert particles and catalyst is used to make the reaction process The thermal energy can be quickly dispersed, which is conducive to temperature control during the experiment.

In a specific embodiment, the temperature change range of the continuous reactor during the hydrogenation reaction is less than 50°C.

The plural inert particles are at least one kind of particles selected from the group consisting of glass beads, barbed wire and Raschig ring, so that the plural Ru/Al ₂ O ₃ catalyst particles in the continuous reactor can be dispersed to avoid Heat accumulates to form hot spots, which causes the temperature of the hydrogenation reaction to change drastically. According to this, the temperature change range of the continuous reactor during the hydrogenation reaction is less than 50°C.

In a specific embodiment, the plurality of inert particles are glass beads.

In another specific embodiment, the plural Ru/Al ₂ O ₃ catalyst particles are granular to facilitate uniform mixing with glass beads, and the shape of the plural Ru/Al ₂ O ₃ catalyst particles is particularly The shape of the ball is better.

In an embodiment, the glass beads have a particle size ranging from 1.0 to 5.0 mm.

In another specific embodiment, the volume of the single Ru/Al ₂ O ₃ catalyst particle and the single inert particle is selected to facilitate uniform dispersion and filling of the plural Ru/Al ₂ O ₃ catalyst particles, It is also advantageous to control the temperature change range of the continuous reactor during the hydrogenation reaction. For example, the volume ratio of the Ru/Al ₂ O ₃ catalyst particles and the inert particles is preferably 1:0.5 to 1. For another example, the volume ratio of the Ru/Al ₂ O ₃ catalyst particles and glass beads is preferably 1: 0.5 to 1

Before the fixed-bed reactor is filled, a mixture containing a plurality of Ru/Al ₂ O ₃ catalyst particles and inert particles such as glass beads is arranged according to the required amount of the reactor bed and divided into four equal parts and uniformly proportioned Mix and then fill the fixed bed reactor in batches to achieve the best distribution effect.

The hydrogenation reaction takes place in the presence of a hydrogenation catalyst, wherein the hydrogenation catalyst includes a hydrogenation metal with a hydrogenation function supported on a carrier. In order to accelerate the hydrogenation reaction, the hydrogenation metal is preferentially distributed in The outer edge of the hydrogenation catalyst, that is, the concentration of the hydrogenation metal in the surface layer of the hydrogenation catalyst is higher than its core, so that the overall loading of the hydrogenation metal and its production cost can be reduced, and the reactants can also be reduced The probability that the surface of the hydrogenation catalyst diffuses to the core effectively improves the selectivity of the process.

In the production method of the present invention, the metal hydride system is ruthenium (Ru), and the carrier system is aluminum oxide (Al ₂ O ₃ ).

In one embodiment, the Ru/Al ₂ O ₃ catalyst particles have a ruthenium metal loading of 0.1 to 5.0% by weight.

In another embodiment, the alumina carrier has a surface area of 50 to 250 square meters/gram.

Compared with the conventional process, one of the characteristics of the method of the present invention is that dimethyl 1,4-cyclohexanedicarboxylate is used as the reaction solvent, and dimethyl terephthalate is dissolved therein to form the reaction Solution, in which no other reaction solvents are used in the reactant solution, which reduces the tedious procedures in the back office, saves the cost of post-processing, and optimizes the process.

Under the conditions of the continuous reactor with plural Ru/Al ₂ O ₃ catalyst particles and inert particles described in the present invention, when the feed concentration increases, the output also increases. In a specific embodiment, the concentration of dimethyl terephthalate in the reactant solution is 5 to 50% by weight.

In a specific embodiment, before the reactant solution is transferred to the continuous reactor, the reactant solution is mixed with hydrogen gas, and the fluid of the mixed reactant solution and hydrogen gas is controlled to reach the desired reaction temperature.

In a specific embodiment, the hydrogenation reaction temperature is 100 to 180°C, preferably 120 to 150°C. However, the temperature of the hydrogenation reaction should not be higher than 180 ℃, to avoid over-reaction, resulting in low reaction selectivity.

Specifically, in a continuous reactor with a plurality of Ru/Al ₂ O ₃ catalyst particles and inert particles, the reactant solution and hydrogen are at a pressure of 20 to 30 kg/cm ² and 100 The hydrogenation reaction is carried out at a temperature of 180°C. In another specific embodiment, in a continuous reactor with a plurality of Ru/Al ₂ O ₃ catalyst particles and inert particles, the reactant solution and hydrogen are at 20 to 30 kg/cm ² (kg/cm ² ) Under the pressure and temperature of 120 to 150 ℃ hydrogenation reaction.

Since the continuous reactor of the present invention is a three-phase reaction system, the flow rate of hydrogen gas will affect the thickness of the liquid layer on the catalyst surface and the mass transfer on the gas-liquid surface. In a specific embodiment, the flow rate of the hydrogen gas is 550 to 3000 unit-minute standard milliliter (sccm).

In the manufacturing method of the present invention, a mixing tank is also provided upstream of the continuous reactor to prepare the reactant solution.

The mixing tank is a continuous device with a stirring device and an electric heating device.

Please refer to FIG. 1, which is a flow chart of the apparatus for preparing the first embodiment of dimethyl 1,4-cyclohexanedicarboxylate according to the present invention. The preparation process includes: respectively from dimethyl terephthalate Storage tank 10 and dimethyl 1,4-cyclohexanedicarboxylate storage tank 11 feed dimethyl terephthalate and dimethyl 1,4-cyclohexanedicarboxylate into a mixing tank 12 at high temperature Under a well-stirred environment, the dimethyl terephthalate is uniformly dissolved in the dimethyl 1,4-cyclohexanedicarboxylate to form the reactant solution; the reactant solution is passed through the pump 13 Before being transferred to the fixed bed reactor 14, the reactant solution is mixed with the hydrogen heated from the hydrogen storage tank 15 via the preheater 16, and the temperature of the mixed reactant solution and the hydrogen fluid is controlled by the temperature controller 17 Reaction temperature; feed the fluid of the mixed reactant solution and hydrogen into the fixed bed reactor 14 with a plurality of Ru/Al ₂ O ₃ catalyst particles and glass beads at 20 to 30 kg/cm ² (kg/cm ² ) The hydrogenation reaction is carried out under the pressure; the dimethyl 1,4-cyclohexanedicarboxylate solution prepared by the fixed bed reactor 14 is output, and can be further reacted through conventional purification procedures or fed into other reactors to prepare 1, 4-Cyclohexane dimethanol (CHDM). For the preparation of 1,4-cyclohexane dimethanol (CHDM), please refer to CN1109859.

In a specific embodiment, the pressure condition of the mixing tank is normal pressure and the temperature setting is 130 to 170°C.

In another embodiment, the temperature of the mixing tank is the same as the temperature of the continuous reactor.

In a specific embodiment, the flow rate of the dimethyl terephthalate into the mixing tank is 5 to 15 ml/min. However, under the conditions of the continuous reactor with a plurality of Ru/Al ₂ O ₃ catalyst particles and a plurality of inert particles described in the present invention, excessive dimethyl terephthalate flow rate only increases production costs and cannot Then increase the reaction volume.

In a specific embodiment, all the storage tanks and pipelines in the above equipment process for preparing dimethyl 1,4-cyclohexanedicarboxylate (that is, the single solid line drawn in the figure connecting each device unit) need to maintain temperature Above 140°C to avoid the problem of pipeline blockage during operation, especially the storage tank and pipeline in front of the fixed bed reactor 14.

In the production method of the present invention, a separation tank is included downstream of the continuous reactor to separate the hydrogen from the dimethyl 1,4-cyclohexanedicarboxylate.

The separation tank is a gas-liquid separation device, and the separated dimethyl 1,4-cyclohexanedicarboxylate can be refluxed or not returned to the mixing tank according to the situation; on the other hand, the separated hydrogen can also be determined according to the situation Choose whether to reflux or not to the fixed bed reactor.

Please refer to FIG. 2, which is a flow chart of the equipment for preparing the second embodiment of dimethyl 1,4-cyclohexanedicarboxylate according to the present invention. The preparation process includes: storage from dimethyl terephthalate The dimethyl terephthalate output from the tank 10 and the dimethyl 1,4-cyclohexanedicarboxylate separated from the separation tank 21 are fed into a mixing tank 12 under high temperature and fully stirred environment. The dimethyl terephthalate is uniformly dissolved in the dimethyl 1,4-cyclohexanedicarboxylate to form the reactant solution; the reactant solution is sent to the fixed bed reactor 14 through the pump 13 Before mixing the reactant solution with hydrogen heated from the hydrogen storage tank 15 via the preheater 16, and using the temperature controller 17 to control the fluid of the mixed reactant solution and hydrogen to the desired reaction temperature; the mixed reaction The fluid of the solution and hydrogen is fed into the fixed-bed reactor 14 with a plurality of Ru/Al ₂ O ₃ catalyst particles and glass beads to perform a hydrogenation reaction under a pressure of 20 to 30 kg/cm ² ; The dimethyl 1,4-cyclohexanedicarboxylate solution prepared by the fixed bed reactor 14 is sent to the separation tank 21 to separate the hydrogen gas from the dimethyl 1,4-cyclohexanedicarboxylate, and The separated dimethyl 1,4-cyclohexanedicarboxylate is pumped back to the mixing tank 12 by a pump 22.

In a specific embodiment, the temperature and pressure conditions of the separation tank are the same as those of the continuous reactor.

The present invention will be further described in detail through examples.

In the following examples, the definitions of DMT conversion rate, DMCD selectivity and hydrogenolysis product selectivity are as follows:

In the following examples, the dimethyl terephthalate (DMT) used was purchased from Acros.

Example 1:

Feed dimethyl terephthalate into a mixing tank at a flow rate of 5 ml/min. Stir with the dimethyl 1,4-cyclohexanedicarboxylate refluxed from the separation tank at a temperature setting of 170°C. And the concentration of the dimethyl terephthalate is 10% by weight, so that the dimethyl terephthalate is uniformly dissolved in the dimethyl 1,4-cyclohexanedicarboxylate to form the reactant solution.

Next, before passing the reactant solution through the pump to the fixed-bed reactor, the reactant solution is mixed with hydrogen heated to 150°C from the hydrogen storage tank through the preheater, and the mixed reaction is controlled by a temperature controller The reaction solution and hydrogen fluid reached a reaction temperature of 150°C; the mixed reaction solution and hydrogen fluid were subjected to a hydrogen-oil ratio of 26 and a flow rate of hydrogen of 1100 unit-minute standard milliliter (sccm). /Al ₂ O ₃ catalyst particles and glass beads fixed bed reactor, under a pressure of 20 kilograms per square centimeter (kg/cm ² ) and a temperature of 150 ℃ under the conditions of hydrogenation.

Before the fixed-bed reactor is filled, the particle size range of the screening Ru/Al ₂ O ₃ catalyst particles is 3.0 mm, wherein the ruthenium loading of the complex Ru/Al ₂ O ₃ catalyst particles is 1.5% by weight, and alumina carrier system which is about 170 m2 / g of surface area, a mixture of catalyst particles and glass beads containing a plurality of configuration Ru / Al ₂ O _3, and the plural Ru / Al ₂ O ₃ catalyst volume of the particles and glass beads The ratio is 1:1, divided into four equal parts and mixed uniformly according to the proportion, and then filled into the fixed bed reactor in batches, so that the total number of Ru/Al ₂ O ₃ catalyst particles and glass beads of the fixed bed reactor The proportion of volume to total volume is 95%.

In this example, the DMT conversion rate was 95.9%, and the DMCD selectivity was 41.2%.

Example 2:

The preparation method is the same as that in Example 1, except that the hydrogenation temperature is 140°C to obtain the product dimethyl 1,4-cyclohexanedicarboxylate. In this example, the DMT conversion rate is 99.0%, and DMCD is selected. The rate is 42.8%.

Example 3:

The preparation method is the same as in Example 1, except that the hydrogenation temperature is 120°C. To obtain the product dimethyl 1,4-cyclohexanedicarboxylate, in this example, the DMT conversion rate was 99.9%, and the DMCD selectivity was 67.0%.

Example 4:

The preparation method is the same as that in Example 1, except that the concentration of dimethyl terephthalate in the reactant solution is 30% by weight to prepare the product dimethyl 1,4-cyclohexanedicarboxylate. In this example Among them, the DMT conversion rate was 97.4%, and the DMCD selectivity was 69.4%.

Example 5:

The preparation method is the same as that in Example 4, except that the flow rate of the hydrogen gas is 2200 standard minutes (sccm) per minute to prepare the product dimethyl 1,4-cyclohexanedicarboxylate. In this example, the DMT conversion The rate was 99.2%, and the DMCD selection rate was 73.7%.

Example 6:

The preparation method is the same as that in Example 4, except that the dimethyl terephthalate is moved at a flow rate of 7.5 ml/min to prepare the product dimethyl 1,4-cyclohexanedicarboxylate. In this example, its DMT The conversion rate was 92.7%, and the DMCD selectivity was 70.8%.

Example 7:

The preparation method is the same as in Example 4, except that the hydrogenation temperature is 120° C. and the pressure is 30 kg/cm ² (kg/cm ² ) to obtain the product dimethyl 1,4-cyclohexanedicarboxylate. In this example, the DMT conversion rate was 99.9%, and the DMCD selectivity was 83%.

Comparative example 1:

The preparation method is the same as in Example 1, except that the carrier of the catalyst is moved to form a Ru/SiO ₂ spherical catalyst, and the Ru/SiO ₂ catalyst has a ruthenium loading of 2% by weight, and the flow rate of hydrogen is 340 units Standard standard milliliter (sccm) per minute, and the concentration of dimethyl terephthalate in the reactant solution is 30% by weight. In this comparative example, the DMT conversion rate was 19.7% and the DMCD selectivity was 67.1%.

Comparative Example 2:

The preparation method is the same as that of Comparative Example 1, except that the carrier of the catalyst is moved to form a Ru/C sheet catalyst, and the Ru/C catalyst has a ruthenium loading of 0.5% by weight. In this comparative example, its DMT conversion The rate was 40.9%, and the DMCD selection rate was 92.2%.

Comparative Example 3:

The preparation method is the same as that of Comparative Example 2, except that the flow rate of the hydrogen gas is 1100 units per minute (sccm). In this comparative example, the DMT conversion rate is 54.4% and the DMCD selectivity is 77.51%.

In summary, in the preparation method of dimethyl 1,4-cyclohexanedicarboxylate of the present invention, a continuous reactor having a plurality of Ru/Al ₂ O ₃ catalyst particles and glass beads is passed through ,4-Cyclohexanedicarboxylic acid dimethyl ester is the reaction solvent, which can continuously prepare 1,4-cyclohexanedicarboxylic acid dimethyl ester under a low pressure environment of 20 to 30 kg/cm ² (kg/cm ^{2 )} . Effectively improve the conversion rate; in addition, the process does not use additional reaction solvents, reducing the cost of post-processing, while reducing the harm to the environment, it has the value of industrial application.

The above-mentioned embodiments are only illustrative and not intended to limit the present invention. Anyone who is familiar with this skill can modify and change the above embodiments without departing from the spirit and scope of the present invention. Therefore, the rights of the present invention The scope of protection is defined by the scope of the patent application attached to the present invention, as long as it does not affect the effect and implementation purpose of the present invention, it should be covered in the technical content of this disclosure.

10‧‧‧ Dimethyl terephthalate storage tank

12‧‧‧Mixing tank

13, 22‧‧‧ Pump

14‧‧‧ Fixed bed reactor

15‧‧‧Hydrogen storage tank

16‧‧‧Preheater

17‧‧‧Temperature Controller

21‧‧‧separating tank

Claims (20)

A preparation method of dimethyl 1,4-cyclohexanedicarboxylate includes: providing a continuous reactor filled with a plurality of Ru/Al ₂ O ₃ catalyst particles with a particle size of 1.5 to 5.0 mm, and the The packing density of the plural Ru/Al ₂ O ₃ catalyst particles of the continuous reactor is 0.4 to 0.7 g/cm 2 (g/cm ³ ), wherein the ruthenium metal of the plural Ru/Al ₂ O ₃ catalyst particles is dispersed The degree is above 13%; and in the continuous reactor, the reaction solution containing dimethyl terephthalate and hydrogen are subjected to hydrogenation reaction under a pressure of 20 to 30 kg/cm ² (kg/cm ² ) To prepare dimethyl 1,4-cyclohexanedicarboxylate; wherein the solvent of the reactant solution is composed of dimethyl 1,4-cyclohexanedicarboxylate to make the terephthalic acid The methyl ester is dissolved in the dimethyl 1,4-cyclohexanedicarboxylate. The preparation method as described in item 1 of the patent application scope, wherein the continuous reactor is a fixed bed reactor. The preparation method as described in item 2 of the patent application range, wherein the plural Ru/Al ₂ O ₃ catalyst particles are spherical. The preparation method as described in item 1 of the patent application range, wherein the plural Ru/Al ₂ O ₃ catalyst particles have an alumina support with a surface area of 50 to 250 m 2 /g. The preparation method as described in item 1 of the patent application range, wherein the ruthenium metal loading of the plural Ru/Al ₂ O ₃ catalyst particles is 0.1 to 5.0% by weight. The preparation method as described in item 1 of the patent application scope, wherein the continuous The reactor is filled with a plurality of inert particles. The preparation method as described in item 6 of the patent application range, wherein the plurality of inert particles are at least one particle selected from the group consisting of glass beads, barbed wire, and Raschig ring. The preparation method as described in item 6 of the patent application range, wherein the volume ratio of the Ru/Al ₂ O ₃ catalyst particles and the inert particles is 1:0.5 to 1. The preparation method as described in item 1 of the patent application scope, wherein the temperature change range of the continuous reactor during the hydrogenation reaction process is less than 50°C. The preparation method as described in item 1 of the patent application scope, wherein the hydrogenation reaction temperature is 100 to 180°C. The preparation method as described in item 1 of the patent application scope further includes mixing the reactant solution and the hydrogen outside the continuous reactor before the hydrogenation reaction of the reactant solution and the hydrogen. The preparation method as described in item 1 of the patent application range, wherein the flow rate of the hydrogen gas is 550 to 3000 unit standard standard milliliter (sccm). The preparation method as described in item 1 of the patent application scope, wherein the concentration of dimethyl terephthalate in the reactant solution is 5 to 50% by weight. The preparation method as described in item 1 of the scope of the patent application includes preparing the reactant solution in a mixing tank provided upstream of the continuous reactor. The preparation method as described in item 14 of the patent application scope, wherein the temperature of the mixing tank is set at 130 to 170°C. The preparation method as described in item 14 of the patent application range, wherein the temperature of the mixing tank is the same as the temperature of the continuous reactor. The preparation method as described in item 14 of the patent application scope, wherein the flow rate of the dimethyl terephthalate into the mixing tank is 5 to 15 ml/min. The preparation method as described in item 1 of the patent application scope further includes separating the hydrogen gas from the dimethyl 1,4-cyclohexanedicarboxylate in a separation tank provided downstream of the continuous reactor. The preparation method as described in item 18 of the patent application scope, wherein the temperature and pressure conditions of the separation tank are the same as those of the continuous reactor. The preparation method as described in item 18 of the patent application scope, further comprising refluxing the separated dimethyl 1,4-cyclohexanedicarboxylate to the mixture in a mixing tank provided upstream of the continuous reactor In the slot.

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