Device and method for producing CHDA through continuous hydrogenation of PTA

Abstract

The invention relates to the technical field of 1, 4-cyclohexanedicarboxylic acid preparation, and discloses a device and a method for producing CHDA (1, 4-cyclohexanedicarboxylic acid) by continuous hydrogenation of PTA (pure terephthalic acid). The device comprises a reactor I and a reactor II which are connected in series, the reactor I and the reactor II are slurry bed reactors, gas inlets and liquid inlets are formed in the lower ends of the reactor I and the reactor II, gas outlets and liquid outlets are formed in the upper ends of the reactor I and the reactor II, gas-liquid-solid separators are arranged at the gas outlets, and solid-liquid separators are arranged at the liquid outlets; liquid storage cavities for storing hydrogenation catalysts are formed in the reactor I and the reactor II. By adopting the device disclosed by the invention, high trans-CHDA selectivity and high product purity can be realized while continuous feeding and continuous discharging are realized.

Description

Technical Field

[0001] The invention relates to the technical field of 1,4-cyclohexanedicarboxylic acid preparation, and in particular to a device and method for producing CHDA by continuous hydrogenation of PTA. Background Art

[0002] 1,4-Cyclohexanedicarboxylic acid (CHDA) is an aliphatic dibasic acid with a symmetrical structure. Its cyclohexane structure has a certain rigidity and does not contain benzene rings. It is less harmful to the human body and the environment. It has been used as an important chemical intermediate to prepare thermoplastic polyesters, epoxy resins and other materials. In addition, the hydrogenation product of CHDA, 1,4-cyclohexanedimethanol (CHDM), is also an important raw material for preparing new polyester products. At present, the preparation methods of CHDA mainly include terephthalate hydrogenation method, terephthalic acid hydrogenation method and hydrolysis method of 1,4-cyclohexanedicarboxylic acid dimethyl ester. Among them, the terephthalic acid hydrogenation method uses terephthalic acid (PTA) as a raw material and directly hydrogenates to obtain CHDA. It has the advantages of low cost of the reaction raw material PTA and simple process steps.

[0003] At present, the research on the preparation of CHDA by hydrogenation of PTA is mostly focused on catalysts and processes, and there are few reports on reaction devices. The direct hydrogenation of terephthalic acid usually uses a solid catalyst. Due to its low solubility in water, terephthalic acid often appears in the form of solid-liquid coexistence in the reaction system, and the hydrogenation raw material hydrogen is a gas, so the reaction process involves gas-liquid-solid three-phase mass transfer and heat transfer, and the reaction system is relatively complex. In addition, CHDA has two isomers, cis-CHDA is a blade-shaped crystal, and trans-CHDA is a phosphorus columnar crystal. Compared with cis-CHDA, trans-CHDA has a higher melting point, and the polyester synthesized from it also has better performance. The control of reaction conditions in the process of PTA hydrogenation to CHDA will affect the reaction selectivity. For example, when the temperature is too high, the selectivity of trans-CHDA will be reduced. Therefore, a suitable reaction device plays a very important role in the application of the PTA hydrogenation to CHDA process.

[0004] The process of preparing CHDA by hydrogenation of traditional PTA is carried out in a batch reaction mode of kettle type. After the reaction is completed, the system is cooled, and the catalyst is filtered to obtain a product liquid (such as patent CN1915958A). The product in the reactor cannot be continuously extracted, and the reactor cannot be operated for a long period of time. The operation is complicated, which greatly reduces the production efficiency. In CN221015945U, a gas-liquid separator and a solid-liquid separator are connected after the hydrogenation reactor to achieve continuous discharging. However, the hydrogenation reactor used therein is a trickle bed reactor, and the reactants are mixed and reacted in the form of drops, which makes it difficult to maintain a stable reaction temperature. For the PTA hydrogenation to prepare CHDA reaction, which has a large reaction selectivity affected by temperature, the problem of low selectivity of trans-CHDA is prone to occur. Summary of the invention

[0005] In order to solve the above technical problem, that is, the existing continuous production of 1,4-cyclohexanedicarboxylic acid devices are prone to low trans-CHDA selectivity, the present invention provides a device and method for producing CHDA by continuous hydrogenation of PTA. The device of the present invention can achieve high trans-CHDA selectivity and high product purity while achieving continuous feeding and continuous discharging.

[0006] The specific technical scheme of the present invention is: In the first aspect, the present invention provides a device for producing CHDA by continuous hydrogenation of PTA, comprising a reactor I and a reactor II connected in series; the reactor I and the reactor II are both slurry bed reactors, and are both provided with a gas inlet and a liquid inlet at the lower end, and a gas outlet and a liquid outlet at the upper end, a gas-liquid-solid separator is provided at the gas outlet, and a solid-liquid separator is provided at the liquid outlet; the reactor I and the reactor II are both provided with a liquid storage chamber storing a hydrogenation catalyst.

[0007] The working process of the above-mentioned device is as follows: the gas inlet and liquid inlet in the reactor I are used to introduce hydrogen and PTA dispersion (which can be a solution or a suspension) respectively. In the liquid storage chamber, PTA and hydrogen contact with the hydrogenation catalyst to undergo a hydrogenation reaction to generate CHDA. The unreacted gas and liquid product (including unreacted PTA and CHDA generated by the reaction) are discharged through the gas outlet and liquid outlet of the reactor I respectively, and then enter the reactor II; in the liquid storage chamber of the reactor II, the unreacted PTA further reacts with hydrogen to generate CHDA, and then the remaining gas and liquid product containing CHDA are discharged through the gas outlet and liquid outlet of the reactor II respectively.

[0008] In the present invention, by using a solid-liquid separator disposed at the liquid outlet and a gas-liquid-solid separator disposed at the gas outlet, the hydrogenation catalyst can be intercepted in the reactor to avoid catalyst loss, and the device can be continuously fed and discharged, achieving long-term stable operation, improving production efficiency and product stability. In addition, by using a gas-liquid-solid separator to reduce the discharge of catalyst and droplets from the gas outlet, it is also possible to avoid blockage of the subsequent process system and affect the long-term operation.

[0009] Furthermore, the slurry bed reactor used in the present invention allows the reactants and the catalyst to react in a uniform slurry state, which is beneficial for maintaining a uniform temperature in the reaction system. For the PTA hydrogenation to CHDA reaction, in which the reaction selectivity is greatly affected by temperature, the trans-CHDA selectivity can be improved. In addition, the slurry bed reactor can also be suitable for large-scale production to improve production efficiency.

[0010] When a slurry bed reactor is applied to the reaction of PTA hydrogenation to CHDA, while having the above advantages, it also has the following problems: due to the low solubility of PTA, when the concentration of PTA in the reaction raw material is high, solid PTA will still exist in the liquid feed, and since a certain degree of back mixing is inevitably present in the slurry bed reactor, a certain amount of PTA will be present in the reaction liquid, and the separation between PTA and CHDA is relatively difficult, and PTA is easily retained in the product, resulting in a low purity of the product. In view of the above problems, the present invention adopts a series of reactors I and II to carry out a two-stage hydrogenation reaction, which can improve the conversion rate of raw material PTA and reduce the PTA content in the final reaction liquid (the liquid discharged through the liquid outlet of reactor II), thereby reducing the difficulty of product refining and purification and improving the purity of CHDA products.

[0011] Preferably, a shell-and-tube heat exchanger is provided in the liquid storage chamber.

[0012] The shell-and-tube heat exchanger arranged in the liquid storage chamber can remove the heat generated by the reaction in time, so that the reaction can be carried out stably at a suitable temperature, thereby making the product composition stable and having a higher trans product selectivity.

[0013] Preferably, the reactor I and the reactor II are further provided with an air storage chamber located above the liquid storage chamber and connected to the liquid storage chamber.

[0014] Furthermore, the liquid outlet is arranged at the upper part of the liquid storage cavity, the air inlet and the liquid inlet are arranged at the lower part of the liquid storage cavity, and the air outlet is arranged at the top of the air storage cavity.

[0015] Preferably, the gas outlet of the reactor I is connected to the gas inlet of the reactor II, and the liquid outlet of the reactor I is connected to the liquid inlet of the reactor II via the heat exchanger I and the liquid phase buffer tank I.

[0016] The use of liquid buffer tank I can stabilize the pressure and flow of logistics to prevent large fluctuations in the system, thereby improving product stability.

[0017] Preferably, the liquid outlet of the reactor II is connected to the product liquid storage tank via the heat exchanger II and the liquid phase buffer tank II.

[0018] Preferably, a gas distributor is provided at the air inlet.

[0019] The gas distributor can evenly disperse the hydrogen into small bubbles and make its distribution more uniform, thereby enhancing the mass transfer of hydrogen in the reaction solution and improving the reaction efficiency.

[0020] Furthermore, the gas distributor is a porous annular tube distributor, wherein the diameter of the gas distribution holes is 0.5 to 5 mm.

[0021] Preferably, the hydrogenation catalyst is a supported catalyst, wherein the support comprises a fullerene / activated carbon composite, and the active components and co-catalysts supported on the support comprise Ru metal, W metal, Ni metal and P element.

[0022] In the hydrogenation catalyst, the pore structure will affect the reaction process, and then affect the reaction selectivity. The present invention finds that when fullerene and activated carbon are composited as carriers, it is beneficial to give the catalyst a more suitable composite pore structure. In addition, Ru metal and W metal are used as active components in the hydrogenation catalyst of the present invention. By using the interaction between the two, the particle size of Ru metal particles can be reduced, so that PTA and hydrogen can be fully contacted with the Ru metal sites in the hydrogenation catalyst. On this basis, the present invention also introduces Ni metal and P element as co-catalysts, and the two cooperate with each other to produce specific effects on the electronic structure and acid sites of the catalyst surface. Through the above-mentioned method, under the joint action of ① fullerene / activated carbon composite carrier + ② Ru metal and W metal active components + ③ Ni metal and P element co-catalysts, the hydrogenation catalyst of the present invention can be used to catalyze PTA hydrogenation to CHDA, when high-priced precious metals (such as Pd, Pt) are not used. , A higher trans product selectivity can be achieved.

[0023] Furthermore, in the hydrogenation catalyst, the P element is loaded on the carrier by means of phosphoric acid impregnation followed by calcination; the calcination temperature is 250-280° C. and the time is 2-3 hours.

[0024] Furthermore, in the hydrogenation catalyst, Ru metal, W metal and Ni metal are loaded on the carrier by reduction after impregnation; during the reduction process, hydrogen is used as a reducing agent, the temperature is 250-280° C., and the time is 2-3 hours.

[0025] Furthermore, in the hydrogenation catalyst, the mass ratio of fullerene to activated carbon is 1:4-49, the loading ratio of Ru metal to W metal is 1:2-30, and the loading ratio of P element to Ni metal is 1:1-5.

[0026] In the present invention, the "loading amount" mentioned refers to the mass percentage of the corresponding component in the hydrogenation catalyst.

[0027] When the ratio of each component in the hydrogenation catalyst is controlled within the above range, the selectivity of trans-CHDA can be improved to a large extent; on this basis, it is more preferred (the selectivity of trans-CHDA can be further improved) that the mass ratio of fullerene to activated carbon is 1:9-19, the loading ratio of Ru metal to W metal is 1:10-20, and the mass ratio of P element to Ni metal is 1:2-5.

[0028] Furthermore, in the hydrogenation catalyst, the loading amount of Ru metal is not less than 0.3wt%, and the total loading amount of P element and Ni metal is 6-20wt%. More preferably, the loading amount of Ru metal is 0.3-2wt%.

[0029] Furthermore, in the hydrogenation catalyst, the carrier is formed by treating fullerene and activated carbon in a dispersion medium at 80 to 100° C. for 1 to 4 hours and then separating a solid product.

[0030] In a second aspect, the present invention provides a method for producing CHDA by continuous hydrogenation of PTA using the device, comprising the following steps: S1: introducing hydrogen gas and terephthalic acid dispersion into the reactor I from the gas inlet and liquid inlet, respectively, to carry out hydrogenation reaction in the reactor I; S2: The unreacted gas in the reactor I is introduced into the reactor II through the gas outlet of the reactor I and the gas inlet of the reactor II, and the liquid product formed in the reactor I is introduced into the reactor II through the liquid outlet of the reactor I and the liquid inlet of the reactor II, and a hydrogenation reaction is carried out in the reactor II.

[0031] S3: The liquid product formed in the reactor II is discharged through the liquid outlet of the reactor II to obtain a product liquid containing CHDA.

[0032] Preferably, in step S1, the liquid hourly space velocity in reactor I is 1 to 5 h -1 , gas hourly space velocity is 10~20h -1 In step S2, the liquid hourly space velocity in reactor II is 5 to 10 h -1 , gas hourly space velocity is 3~10h -1 .

[0033] In the present invention, the liquid hourly space velocity in reactor I refers to the volumetric space velocity of the terephthalic acid dispersion in reactor I, the gas hourly space velocity in reactor I refers to the volumetric space velocity of hydrogen in reactor I, the liquid hourly space velocity in reactor II refers to the volumetric space velocity of the liquid introduced into reactor II, and the gas hourly space velocity in reactor II refers to the volumetric space velocity of the gas introduced into reactor II.

[0034] Preferably, in steps S1 and S2, the hydrogenation reaction temperature in reactor I and reactor II is both 100-250°C.

[0035] Preferably, in step S1, the concentration of the terephthalic acid dispersion is 5 to 20 wt%.

[0036] Preferably, in step S1, the terephthalic acid dispersion is a solution or suspension containing terephthalic acid.

[0037] Compared with the prior art, the present invention has the following advantages: (1) The present invention utilizes a solid-liquid separator and a gas-liquid-solid separator respectively disposed at the liquid outlet and gas outlet of the reactor, which can realize continuous feeding and discharging of materials, enable the device to operate stably for a long period of time, and improve production efficiency and product stability.

[0038] (2) The present invention uses two slurry bed reactors connected in series to carry out a two-stage hydrogenation reaction, which can achieve higher trans-CHDA selectivity and higher product purity.

[0039] (3) In the hydrogenation catalyst used in the present invention, under the joint action of ① fullerene / activated carbon composite carrier + ② Ru metal and W metal active components + ③ Ni metal and P element co-catalysts, a higher trans-CHDA selectivity can be achieved without using expensive precious metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The present invention is a schematic structural diagram of a device for producing CHDA by continuous hydrogenation of PTA.

[0041] The figures are marked as follows: 1-reactor I, 2-reactor II, 3-air inlet, 4-liquid inlet, 5-air outlet, 6-liquid outlet, 7-gas-liquid-solid separator, 8-solid-liquid separator, 9-liquid storage chamber, 10-shell-and-tube heat exchanger, 11-air storage chamber, 12-heat exchanger I, 13-liquid phase buffer tank I, 14-heat exchanger II, 15-liquid phase buffer tank II, 16-product liquid storage tank, 17-gas distributor. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the embodiments.

[0043] Overall embodiment A device for producing CHDA by continuous hydrogenation of PTA comprises a reactor I1 and a reactor II2 connected in series; the reactor I1 and the reactor II2 are both slurry bed reactors, and are both provided with a gas inlet 3 and a liquid inlet 4 at the lower end, a gas outlet 5 and a liquid outlet 6 at the upper end, a gas-liquid-solid separator 7 is provided at the gas outlet 5, and a solid-liquid separator 8 is provided at the liquid outlet 6; the reactor I1 and the reactor II2 are both provided with a liquid storage cavity 9 storing a hydrogenation catalyst.

[0044] In some specific embodiments, a shell-and-tube heat exchanger 10 is provided in the liquid storage chamber 9 .

[0045] In some specific embodiments, the reactor I1 and the reactor II 2 are further provided with an air storage chamber 11 located above the liquid storage chamber 9 and in communication with the liquid storage chamber 9. In this specific embodiment, optionally or preferably: the liquid outlet 6 is provided at the upper part of the liquid storage chamber 9, the air inlet 3 and the liquid inlet 4 are provided at the lower part of the liquid storage chamber 9, and the air outlet 5 is provided at the top of the air storage chamber 11.

[0046] In some specific embodiments, the gas outlet 5 of the reactor I1 is connected to the gas inlet 3 of the reactor II 2, and the liquid outlet 6 of the reactor I1 is connected to the liquid inlet 4 of the reactor II 2 via the heat exchanger I12 and the liquid phase buffer tank I13.

[0047] In some specific embodiments, the liquid outlet 6 of the reactor II 2 is connected to the product liquid storage tank 16 via the heat exchanger II 14 and the liquid phase buffer tank II 15 .

[0048] In some specific embodiments, a gas distributor 17 is provided at the gas inlet 3; the gas distributor 17 is a porous annular tube distributor, wherein the diameter of the gas distribution holes is 0.5 to 5 mm.

[0049] In some specific embodiments, the hydrogenation catalyst is a supported catalyst, wherein the support comprises a fullerene / activated carbon composite, and the active components and co-catalysts supported on the support comprise Ru metal, W metal, Ni metal and P element. In this specific embodiment, optionally or preferably: In the hydrogenation catalyst, the mass ratio of fullerene to activated carbon is 1:4-49, the loading ratio of Ru metal to W metal is 1:2-30, the loading ratio of P element to Ni metal is 1:1-5, the loading of Ru metal is not less than 0.3wt%, and the total loading of P element and Ni metal is 6-20wt%; In the hydrogenation catalyst, the P element is loaded on the carrier by phosphoric acid impregnation and then calcination; the calcination temperature is 250-280° C. and the time is 2-3 hours; In the hydrogenation catalyst, Ru metal, W metal and Ni metal are loaded on the carrier by reduction after impregnation; during the reduction process, hydrogen is used as a reducing agent, the temperature is 250-280° C., and the time is 2-3 hours; In the hydrogenation catalyst, the carrier is formed by treating fullerene and activated carbon in a dispersion medium at 80 to 100° C. for 1 to 4 hours and then separating a solid product.

[0050] A method for producing CHDA by continuous hydrogenation of PTA using the device comprises the following steps: S1: introducing hydrogen gas and terephthalic acid dispersion into the reactor I from the gas inlet and liquid inlet, respectively, to carry out hydrogenation reaction in the reactor I; S2: The unreacted gas in the reactor I is introduced into the reactor II through the gas outlet of the reactor I and the gas inlet of the reactor II, and the liquid product formed in the reactor I is introduced into the reactor II through the liquid outlet of the reactor I and the liquid inlet of the reactor II, and a hydrogenation reaction is carried out in the reactor II.

[0051] S3: The liquid product formed in the reactor II is discharged through the liquid outlet of the reactor II to obtain a product liquid containing CHDA.

[0052] In some specific embodiments, in step S1, the terephthalic acid dispersion is a solution or suspension containing terephthalic acid with a concentration of 5 to 20 wt%.

[0053] In some specific embodiments, in step S1, the liquid hourly space velocity in reactor I is 1 to 5 h -1 , gas hourly space velocity is 10~20h -1 In step S2, the liquid hourly space velocity in reactor II is 5 to 10 h -1 , gas hourly space velocity is 3~10h -1 .

[0054] In some specific embodiments, in steps S1 and S2, the hydrogenation reaction temperature in reactor I and reactor II is both 100-250°C. Specific embodiments The technical solution of the present invention is described clearly and completely below in conjunction with specific embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Example 1 This embodiment relates to a device for producing CHDA by continuous hydrogenation of PTA, the structure of which is as follows: Figure 1As shown, the specific structure is as follows: it includes a reactor I1 and a reactor II 2, both of which are slurry bed reactors. The structure of the reactor I1 is as follows: a gas storage chamber 11 and a liquid storage chamber 9 are provided inside the reactor I1, the gas storage chamber 11 is located at the top of the reactor I1, and the liquid storage chamber 9 is located below the gas storage chamber 11, and the liquid storage chamber 9 stores a hydrogenation catalyst and is provided with a shell-and-tube heat exchanger 10; a gas outlet 5 is provided on the shell of the reactor I1 located at the top of the gas storage chamber 11, and a gas-liquid-solid separator 7 is provided at the gas outlet 5; a liquid outlet 6 is provided on the shell of the reactor I1 located above the liquid storage chamber 9, and a solid-liquid separator 8 is provided at the liquid outlet 6; a liquid inlet 4 and a gas inlet 3 are provided at the bottom and near the bottom of the shell of the reactor I1, respectively, the liquid inlet 4 and the gas inlet 3 are both located below the gas storage chamber 11, and a gas distributor 17 is provided at the gas inlet 3, and the gas distributor 17 is a multi-hole annular tube distributor, wherein the aperture of the gas distribution hole is 2 mm. The structure of the reactor II 2 is the same as that of the reactor I1. The gas outlet 5 of reactor I1 is connected to the gas inlet 3 of reactor II 2; the liquid outlet 6 of reactor I1 is connected to the liquid inlet 4 of reactor II 2 via heat exchanger I12 and liquid phase buffer tank I13; the liquid outlet 6 of reactor II 2 is connected to the product liquid storage tank 16 via heat exchanger II14 and liquid phase buffer tank II 15.

[0057] In the above device, 16 hydrogenation catalysts in Table 1 were used for testing respectively. These hydrogenation catalysts were prepared by the following steps: (1) According to the carrier composition (mass ratio between fullerene and activated carbon) in Table 1, weigh fullerene and activated carbon. Mix fullerene with 20 times the mass of dimethyl oxalate and stir vigorously for 30 minutes to obtain a fullerene dispersion. Mix activated carbon with 20 times the mass of pure water and stir vigorously for 30 minutes to obtain an activated carbon dispersion. After the fullerene dispersion and the activated carbon dispersion are stirred and mixed, they are transferred to a hydrothermal autoclave, reacted at 95°C for 3 hours, cooled, and centrifuged to separate the solid, then washed with anhydrous ethanol and pure water three times respectively, filtered, and dried in an oven at 100°C for 12 hours to obtain a fullerene / activated carbon composite.

[0058] (2) According to the loading amounts of the four elements Ru, W, P, and Ni in Table 1, weigh the corresponding masses of ruthenium trichloride, ammonium tungstate, phosphoric acid, and nickel acetate, and dissolve them in pure water to obtain an impregnation solution. The impregnation solution is mixed with the fullerene / activated carbon composite, impregnated for 24 hours, and then dried in a vacuum drying oven at 100°C for 12 hours, and then reduced with a 10 vol% hydrogen-nitrogen mixed gas at 250°C for 2 hours to obtain a hydrogenation catalyst.

[0059] Table 1 Composition of hydrogenation catalyst Note: 1 Fullerene / activated carbon (m / m): refers to the mass ratio between fullerene and activated carbon; 2 0 / 100: means that the carrier is composed entirely of activated carbon and does not contain fullerene; 3 100 / 0: means that the carrier is composed entirely of fullerenes and does not contain activated carbon.

[0060] The above device is used to continuously hydrogenate PTA to produce CHDA, and the steps are as follows: S1: Mix terephthalic acid and water to obtain a PTA dispersion with a concentration of 20 wt%. In reactor I, hydrogen is introduced from the gas inlet, and the PTA dispersion is introduced from the liquid inlet. The dispersion is contacted with the hydrogenation catalyst in the liquid storage chamber to carry out a hydrogenation reaction. In reactor I, the temperature in the liquid storage chamber is set to 150°C, and the liquid hourly space velocity is set to 2h -1 , the gas hourly space velocity is set to 10h -1 .

[0061] S2: The unreacted gas in the reactor I enters the gas storage chamber, and after separation by the gas-liquid-solid separator, the liquid phase and the solid phase flow back into the reactor I, and the gas phase is discharged from the gas outlet. The liquid product formed in the reactor I is separated by the solid-liquid separator, and the solid phase is intercepted in the liquid storage chamber, and the liquid phase is discharged from the liquid outlet, cooled by the heat exchanger I, and buffered in the liquid phase buffer tank I.

[0062] S3: The gas phase is discharged from the gas outlet of reactor I and then flows to the gas inlet of reactor II, and the liquid in the liquid buffer tank flows to the liquid inlet of reactor II. In the liquid storage chamber of reactor II, the remaining PTA and hydrogen contact with the hydrogenation catalyst to carry out the hydrogenation reaction. In reactor II, the temperature in the liquid storage chamber is set to 120°C, and the liquid hourly space velocity is set to 6h -1 , the gas hourly space velocity is set to 5h -1 .

[0063] S4: The unreacted gas in the reactor II enters the gas storage chamber, and after separation by the gas-liquid-solid separator, the liquid phase and the solid phase flow back into the reactor II, and the gas phase is discharged from the gas outlet. The liquid product formed in the reactor II is separated by the solid-liquid separator, and the solid phase is intercepted in the liquid storage chamber, and the liquid phase is discharged from the liquid outlet, and after cooling by the heat exchanger II, it is stored in the product liquid storage tank. Samples are taken from the product liquid storage tank, and the PTA content, cis-CHDA content and trans-CHDA content therein are detected, and the PTA conversion rate, cis-CHDA selectivity and trans-CHDA selectivity are calculated. The results are shown in Table 2.

[0064] Table 2 Reaction degree and reaction selectivity test results Test results analysis and conclusion: (1) By comparing the test results when using hydrogenation catalysts E-1 to E-5, it can be seen that the use of fullerene / activated carbon composites (E-2, E-3, E-4) as carriers can achieve higher trans-CHDA selectivity than the use of fullerene and activated carbon alone (E-1, E-5). This may be because the fullerene / activated carbon composite has a more suitable composite pore structure, which is conducive to the PTA hydrogenation reaction to produce CHDA.

[0065] (2) Comparing the test results when using hydrogenation catalysts E-3 and E-6 to E-9, it can be seen that when the loading ratio of Ru metal to W metal is 1:2 to 30 (E-3, E-7, E-8), a higher trans-CHDA selectivity can be achieved; when the loading ratio of the two active components is lower than 1:2 (E-6) and higher than 1:30 (E-9), the trans-CHDA selectivity will decrease. This may be because when the loading ratio of Ru metal to W metal is too low, the interaction between the two cannot be effectively utilized to reduce the particle size of Ru metal particles; and when the loading ratio of Ru metal to W metal is too high, W metal will over-cover the Ru metal sites.

[0066] (3) Comparing the test results when using hydrogenation catalysts E-3 and E-10 to E-16, it can be seen that in the catalyst system composed of fullerene / activated carbon composite carrier and active components Ru metal and W metal, by introducing P element and Ni metal (E-3, E-14, E-15) with a loading ratio of 1:1 to 5 as co-catalysts, the trans-CHDA selectivity can be effectively improved. When P element (E-11) or Ni metal (E-12) is introduced alone, or the ratio between P element and Ni metal is improperly set (E-13, E-16), the trans-CHDA selectivity is lower than when no co-catalyst (E-10) is introduced. This may be because the P element and Ni metal can have a specific effect on the electronic structure and acid sites of the catalyst surface after cooperating with each other in a suitable ratio, thereby improving the trans product selectivity.

[0067] Example 2 This embodiment relates to a device for producing CHDA by continuous hydrogenation of PTA, the structure of which is as follows: Figure 1As shown, the specific structure is as follows: it includes a reactor I1 and a reactor II 2, both of which are slurry bed reactors. The structure of the reactor I1 is as follows: a gas storage chamber 11 and a liquid storage chamber 9 are provided inside the reactor I1, the gas storage chamber 11 is located at the top of the reactor I1, and the liquid storage chamber 9 is located below the gas storage chamber 11, and the liquid storage chamber 9 stores a hydrogenation catalyst and is provided with a shell-and-tube heat exchanger 10; a gas outlet 5 is provided on the shell of the reactor I1 located at the top of the gas storage chamber 11, and a gas-liquid-solid separator 7 is provided at the gas outlet 5; a liquid outlet 6 is provided on the shell of the reactor I1 located at the upper part of the liquid storage chamber 9, and a solid-liquid separator 8 is provided at the liquid outlet 6; a liquid inlet 4 and a gas inlet 3 are provided at the bottom and near the bottom of the shell of the reactor I1, respectively, the liquid inlet 4 and the gas inlet 3 are both located below the gas storage chamber 11, and a gas distributor 17 is provided at the gas inlet 3, and the gas distributor 17 is a multi-hole annular tube distributor, wherein the aperture of the gas distribution hole is 0.5 mm. The structure of reactor II 2 is the same as that of reactor I1. The gas outlet 5 of reactor I1 is connected to the gas inlet 3 of reactor II 2; the liquid outlet 6 of reactor I1 is connected to the liquid inlet 4 of reactor II 2 via heat exchanger I12 and liquid phase buffer tank 13; the liquid outlet 6 of reactor II 2 is connected to product liquid storage tank 16 via heat exchanger II14 and liquid phase buffer tank II15.

[0068] In the above device, the hydrogenation catalyst used is E-3 in Example 1.

[0069] The above device is used to continuously hydrogenate PTA to produce CHDA, and the steps are as follows: S1: Mix terephthalic acid and water to obtain a PTA dispersion with a concentration of 5 wt%. In reactor I, hydrogen is introduced from the gas inlet, and the PTA dispersion is introduced from the liquid inlet. The dispersion is contacted with the hydrogenation catalyst in the liquid storage chamber to carry out a hydrogenation reaction. In reactor I, the temperature in the liquid storage chamber is set to 200°C, and the liquid hourly space velocity is set to 5h -1 , the gas hourly space velocity is set to 20h -1 .

[0070] S2: The unreacted gas in the reactor I enters the gas storage chamber, and after separation by the gas-liquid-solid separator, the liquid phase and the solid phase flow back into the reactor I, and the gas phase is discharged from the gas outlet. The liquid product formed in the reactor I is separated by the solid-liquid separator, and the solid phase is intercepted in the liquid storage chamber, and the liquid phase is discharged from the liquid outlet, cooled by the heat exchanger I, and buffered in the liquid phase buffer tank.

[0071] S3: The gas phase is discharged from the gas outlet of reactor I and then flows to the gas inlet of reactor II, and the liquid in the liquid buffer tank flows to the liquid inlet of reactor II. In the liquid storage chamber of reactor II, the remaining PTA and hydrogen are in contact with the hydrogenation catalyst to carry out the hydrogenation reaction. In reactor II, the temperature in the liquid storage chamber is set to 100°C, and the liquid hourly space velocity is set to 5h -1, the gas hourly space velocity is set to 3h -1 .

[0072] S4: The unreacted gas in the reactor II enters the gas storage chamber, and after separation by the gas-liquid-solid separator, the liquid phase and the solid phase flow back into the reactor II, and the gas phase is discharged from the gas outlet. The liquid product formed in the reactor II is separated by the solid-liquid separator, and the solid phase is intercepted in the liquid storage chamber, and the liquid phase is discharged from the liquid outlet, cooled by the heat exchanger II, and stored in the product liquid storage tank.

[0073] Example 3 This embodiment relates to a device for producing CHDA by continuous hydrogenation of PTA, the structure of which is as follows: Figure 1 As shown, the specific structure is as follows: it includes a reactor I1 and a reactor II 2, both of which are slurry bed reactors. The structure of the reactor I1 is as follows: a gas storage chamber 11 and a liquid storage chamber 9 are provided inside the reactor I1, the gas storage chamber 11 is located at the top of the reactor I1, and the liquid storage chamber 9 is located below the gas storage chamber 11, and the liquid storage chamber 9 stores a hydrogenation catalyst and is provided with a shell-and-tube heat exchanger 10; a gas outlet 5 is provided on the shell of the reactor I1 located at the top of the gas storage chamber 11, and a gas-liquid-solid separator 7 is provided at the gas outlet 5; a liquid outlet 6 is provided on the shell of the reactor I1 located at the upper part of the liquid storage chamber 9, and a solid-liquid separator 8 is provided at the liquid outlet 6; a liquid inlet 4 and a gas inlet 3 are provided at the bottom and near the bottom of the shell of the reactor I1, respectively, the liquid inlet 4 and the gas inlet 3 are both located below the gas storage chamber 11, and a gas distributor 17 is provided at the gas inlet 3, and the gas distributor 17 is a multi-hole annular tube distributor, wherein the aperture of the gas distribution hole is 5 mm. The structure of the reactor II 2 is the same as that of the reactor I1. The gas outlet 5 of reactor I1 is connected to the gas inlet 3 of reactor II 2; the liquid outlet 6 of reactor I1 is connected to the liquid inlet 4 of reactor II 2 via heat exchanger I12 and liquid phase buffer tank 13; the liquid outlet 6 of reactor II 2 is connected to the product liquid storage tank 16 via heat exchanger II 14 and liquid phase buffer tank II 15.

[0074] In the above device, the hydrogenation catalyst used is E-3 in Example 1.

[0075] The above device is used to continuously hydrogenate PTA to produce CHDA, and the steps are as follows: S1: Mix terephthalic acid and water to obtain a PTA dispersion with a concentration of 10 wt%. In reactor I, hydrogen is introduced from the gas inlet, and the PTA dispersion is introduced from the liquid inlet. The dispersion is contacted with the hydrogenation catalyst in the liquid storage chamber to carry out a hydrogenation reaction. In reactor I, the temperature in the liquid storage chamber is set to 160°C, and the liquid hourly space velocity is set to 1h -1 , the gas hourly space velocity is set to 15h -1 .

[0076] S2: The unreacted gas in the reactor I enters the gas storage chamber, and after separation by the gas-liquid-solid separator, the liquid phase and the solid phase flow back into the reactor I, and the gas phase is discharged from the gas outlet. The liquid product formed in the reactor I is separated by the solid-liquid separator, and the solid phase is intercepted in the liquid storage chamber, and the liquid phase is discharged from the liquid outlet, cooled by the heat exchanger I, and buffered in the liquid phase buffer tank.

[0077] S3: The gas phase is discharged from the gas outlet of reactor I and then flows to the gas inlet of reactor II, and the liquid in the liquid buffer tank flows to the liquid inlet of reactor II. In the liquid storage chamber of reactor II, the remaining PTA and hydrogen are in contact with the hydrogenation catalyst to carry out the hydrogenation reaction. In reactor II, the temperature in the liquid storage chamber is set to 120°C, and the liquid hourly space velocity is set to 10h -1 , the gas hourly space velocity is set to 10h -1 .

[0078] S4: The unreacted gas in the reactor II enters the gas storage chamber, and after separation by the gas-liquid-solid separator, the liquid phase and the solid phase flow back into the reactor II, and the gas phase is discharged from the gas outlet. The liquid product formed in the reactor II is separated by the solid-liquid separator, and the solid phase is intercepted in the liquid storage chamber, and the liquid phase is discharged from the liquid outlet, cooled by the heat exchanger II, and stored in the product liquid storage tank.

[0079] Unless otherwise specified, the devices, connection structures and methods involved in the present invention are all devices, connection structures and methods well known in the art.

[0080] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A device for producing CHDA by continuous hydrogenation of PTA, characterized in that: The invention comprises a reactor I (1) and a reactor II (2) connected in series; the reactor I (1) and the reactor II (2) are both slurry bed reactors, and are both provided with a gas inlet (3) and a liquid inlet (4) at the lower end, and a gas outlet (5) and a liquid outlet (6) at the upper end; a gas-liquid-solid separator (7) is provided at the gas outlet (5), and a solid-liquid separator (8) is provided at the liquid outlet (6); and the reactor I (1) and the reactor II (2) are both provided with a liquid storage chamber (9) storing a hydrogenation catalyst.

2. The device according to claim 1, characterized in that A shell-and-tube heat exchanger (10) is provided in the liquid storage cavity (9).

3. The device according to claim 1, characterized in that The reactor I (1) and the reactor II (2) are further provided with an air storage chamber (11) located above the liquid storage chamber (9) and connected to the liquid storage chamber (9).

4. The device according to claim 3, characterized in that The liquid outlet (6) is arranged at the upper part of the liquid storage chamber (9), the air inlet (3) and the liquid inlet (4) are arranged at the lower part of the liquid storage chamber (9), and the air outlet (5) is arranged at the top of the air storage chamber (11).

5. The device according to claim 1, characterized in that The gas outlet (5) of the reactor I (1) is connected to the gas inlet (3) of the reactor II (2), and the liquid outlet (6) of the reactor I (1) is connected to the liquid inlet (4) of the reactor II (2) via a heat exchanger I (12) and a liquid phase buffer tank I (13).

6. The device according to claim 1, characterized in that The liquid outlet (6) of the reactor II (2) is connected to the product liquid storage tank (16) via the heat exchanger II (14) and the liquid phase buffer tank II (15).

7. The device according to claim 1, characterized in that A gas distributor (17) is provided at the gas inlet (3).

8. The device according to claim 1, characterized in that The hydrogenation catalyst is a supported catalyst, wherein the support comprises a fullerene / activated carbon composite, and the active components and co-catalysts supported on the support comprise Ru metal, W metal, Ni metal and P element.

9. The device according to claim 8, characterized in that In the hydrogenation catalyst, the P element is loaded on the carrier by means of phosphoric acid impregnation followed by calcination; the calcination temperature is 250-280° C. and the calcination time is 2-3 hours.

10. A method for producing CHDA by continuous hydrogenation of PTA using the device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: introducing hydrogen gas and terephthalic acid dispersion into the reactor I from the gas inlet and liquid inlet, respectively, to carry out hydrogenation reaction in the reactor I; S2: passing the unreacted gas in the reactor I into the reactor II through the gas outlet of the reactor I and the gas inlet of the reactor II, and passing the liquid product formed in the reactor I into the reactor II through the liquid outlet of the reactor I and the liquid inlet of the reactor II, and performing a hydrogenation reaction in the reactor II; S3: The liquid product formed in the reactor II is discharged through the liquid outlet of the reactor II to obtain a product liquid containing CHDA.

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