Crude terephthalic acid hydrogenation purification catalyst, its preparation method, and its application

Abstract

A crude terephthalic acid hydrogenation purification catalyst, a method for preparing the same, and an application thereof are disclosed. The catalyst includes a carrier and an active ingredient. The active ingredient includes palladium and ruthenium, and the weight ratio of palladium to ruthenium, in terms of elements, is (3 to 10):1. Palladium is Pd 0 and ruthenium is Ru 0 and Ru 4+ and includes Ru 4+ the weight ratio of Ru 0 is 0.1 to 1.0. The catalyst provided by the present invention has excellent catalytic activity and anti-sintering performance and is particularly suitable for the hydrogenation purification reaction of crude terephthalic acid. The catalyst of the present invention can cause the hydrogenation purification reaction to proceed efficiently and stably.

Description

Detailed Description of the Invention

[0001] 〔Technical Field〕 The present disclosure relates to a catalyst for the hydrogenation purification of crude terephthalic acid. In particular, the present disclosure relates to a supported catalyst for the hydrogenation purification of crude terephthalic acid containing a plurality of active components, as well as methods for their preparation and applications.

[0002] 〔Background〕 p-Terephthalic acid (terephthalic acid, TA) is an important industrial raw material. Terephthalic acid is used in the production of polyethylene terephthalate (PET), which is then used to produce products such as fibers, bottles, films, etc. Terephthalic acid can also be used in the production of polybutylene terephthalate (PBT) engineering plastics, etc. Currently, terephthalic acid is mainly produced by liquid-phase oxidation by using p-xylene as the raw material, acetic acid as the solvent, air as the oxidant, and Co / Mn / Br as the catalyst system. The resulting product after the reaction may contain by-products and impurities and is generally called crude terephthalic acid (CTA). By-products may include p-toluyl alcohol (TALC), p-tolualdehyde (TALD), p-toluic acid, p-carboxybenzaldehyde (4-CBA), etc. In subsequent procedures for preparing polyester, the presence of 4-CBA can have an adverse effect on the color and quality of the resulting polyester. Crude terephthalic acid typically contains up to 9000 ppm of 4-CBA and thus cannot meet the standards for producing polyester. Many methods have been proposed to remove impurities and by-products, especially 4-CBA, from crude terephthalic acid to obtain purified terephthalic acid (PTA). Purified terephthalic acid generally refers to a purified product that contains at least a lower amount of 4-CBA than crude terephthalic acid. Purified terephthalic acid qualified for polymerization may contain 25 ppm or less of 4-CBA. 4-CBA in crude terephthalic acid can usually be removed by hydrogenation purification, i.e., converting other compounds (such as p-toluic acid) by hydrogenation and then separating and purifying by crystallization. Hydrogenation purification of crude terephthalic acid may usually use a palladium / carbon catalyst.

[0003] A single active ingredient is used in the palladium / carbon catalyst. Therefore, the distribution of palladium metal on the carrier can have a profound impact on the performance of the catalyst. On the one hand, hydrogenation purification is a primary reaction and has a fast reaction rate. In this regard, it is difficult for reaction molecules to penetrate into the interior of catalyst particles during the reaction. This means that the active ingredient inside the particles may not be able to contact the reaction molecules due to steric hindrance and thus may not be able to function. In such a case, only the active ingredient on the outer surface exhibits catalytic activity. In order to fully utilize the active ingredient (palladium), the palladium / carbon catalyst is usually made to have a shell in which the active ingredient (palladium) is mainly supported on the surface of the carrier (i.e., a core-shell structure). Since the active ingredient (palladium) of the core-shell catalyst is mainly concentrated on the surface of the carrier, the catalyst has a larger surface area in contact with reaction molecules than a catalyst in which the same amount of active ingredient is dispersed throughout the carrier, and thus may have more efficient catalytic ability. On the other hand, hydrogenation purification is usually operated under reaction pressure conditions of 6.5 - 8.5 MPa and a reaction temperature of 250 - 290 °C. Under such reaction conditions, grain growth of the active ingredient (palladium) is inevitable. One of the main reasons for catalyst deactivation is simply the grain growth of palladium. While the corresponding new catalyst can have palladium grains of 2 - 5 nm, a commercially available palladium / carbon catalyst for hydrogenation purification of crude terephthalic acid that has been deactivated may have palladium grains grown to 20 nm or more. The faster the grain growth of palladium, the shorter the catalyst life, resulting in significant economic losses.

[0004] In order to improve the lifespan of catalysts for the hydrogenation purification of crude terephthalic acid, many methods have been proposed, including, for example, using multiple active components. For example, US4,892,972 discloses a double-layer catalyst that uses Pd / C and Rh / C and has Pd and Rh in a ratio of 10:1. When used for the hydrogenation purification of crude terephthalic acid, it has been found that the lifespan of the said catalyst is significantly improved. Although the grains of Rh are difficult to grow, the price of Rh is 10 times that of Pd. Therefore, such catalysts are not actually applicable. It has also been proposed to use supported bimetallic catalysts containing Pd and Ru. In the preparation of such catalysts, the Ru source cannot be easily reduced to metallic Ru. In addition, such catalysts may require a carrier such as titanium dioxide. These carriers may have poor acid and alkali resistance and may not be suitable for the reaction conditions for the hydrogenation purification of crude terephthalic acid.

[0005] Improvements in the activity and thermal stability of catalysts for the hydrogenation purification of crude terephthalic acid have been achieved in the art. However, the need for further improvement in the activity and thermal stability of catalysts for the hydrogenation purification of crude terephthalic acid always exists.

[0006] 〔Summary of the Invention〕 The present disclosure is for solving the problem in the prior art that the hydrogenation purification reaction of crude terephthalic acid can be plagued by a low conversion rate of 4-CBA and poor thermal stability of the catalyst. In this regard, what is provided in the present disclosure is a novel catalyst for the hydrogenation purification of crude terephthalic acid, which catalyst contains multiple active components. The catalyst according to the present disclosure can have excellent catalytic activity and anti-sintering performance and can be particularly suitable for hydrogenating and purifying crude terephthalic acid. The catalyst according to the present disclosure can make the hydrogenation purification more efficient and stable. The present disclosure also relates to a method for preparing the said catalyst and the use of the catalyst in the hydrogenation purification of crude terephthalic acid.

[0007] In one aspect, provided in the present disclosure is a catalyst for hydrogenating and purifying crude terephthalic acid, comprising a carrier and an active ingredient, wherein the active ingredient comprises palladium and ruthenium, palladium and ruthenium are in a weight ratio of (3 - 10):1 on an elemental basis, palladium is Pd 0 and ruthenium is Ru 0 and Ru 4+ and comprises, Ru 4+ and Ru 0 and are in a weight ratio of 0.1 - 1.0, the catalyst being such.

[0008] In a further aspect, provided in the present disclosure is a method for preparing the above catalyst for hydrogenating and purifying crude terephthalic acid, comprising: (1) a step of providing a catalyst carrier; (2) a step of mixing the catalyst carrier of step (1) with a source of active metal and an alkylamine, subjecting the resulting mixture to aging and a first heat treatment to obtain a catalyst precursor; (3) a step of reducing the catalyst precursor of step (2) with a reducing agent to obtain the catalyst. The method is such.

[0009] In an even further aspect, provided in the present disclosure is the use of the above catalyst for hydrogenating and purifying crude terephthalic acid in the hydrogenation purification reaction of crude terephthalic acid.

[0010] In particular, the present disclosure may include the following items.

[0011] 1. A catalyst for hydrogenating and purifying crude terephthalic acid, comprising a carrier and an active ingredient, wherein the active ingredient is metallic palladium and metallic ruthenium, metallic palladium and metallic ruthenium are in a weight ratio of (3 - 10):1, the valence state of metallic palladium is Pd0 and the valence state of metallic ruthenium is Ru 0 and Ru 4+ and a catalyst.

[0012] 2. In the catalyst, Ru 4+ and Ru 0 exist in a weight ratio of 0.1 to 1.0, The catalyst according to item 1, characterized in that.

[0013] 3. The carrier is activated carbon, Preferably, the activated carbon is at least one selected from the group consisting of coal-based activated carbon, wood activated carbon, and nut shell activated carbon, The catalyst according to item 1, characterized in that.

[0014] 4. A method for preparing the catalyst according to any one of items 1 to 3, (1) A step of pretreating activated carbon to obtain a catalyst carrier; (2) A step of mixing an active metal, an alkylamine, and a solvent to obtain a catalyst precursor i; (3) A step of mixing the catalyst carrier in step (1) with the catalyst precursor i in step (2) and subjecting it to aging, desolvation, and heat treatment to obtain a catalyst precursor ii; (4) A step of reducing the catalyst precursor ii in step (3) with a reducing agent and subjecting it to heat treatment to obtain the catalyst; A method comprising.

[0015] 5. The alkyl group of the alkylamine in step (2) is selected from the group consisting of C3 to C20 alkyls, The method according to item 4, characterized in that.

[0016] 6. The active metals in step (2) are palladium and ruthenium, The source of palladium and the source of ruthenium are a palladium salt and a ruthenium salt, The palladium salt is at least one selected from the group consisting of palladium nitrate, palladium acetate, chloropalladic acid and its salts, and tetraammine dichloropalladium, preferably palladium acetate, The ruthenium salt is at least one selected from the group consisting of ruthenium nitrate, ruthenium acetate, and ruthenium trichloride, preferably ruthenium acetate, The method according to item 4, characterized in that.

[0017] 7. In step (2), the mass ratio of the solvent, the alkylamine, and the active metal is (5000 to 30000):(20 to 50):(5 to 20), As the active metals, the mass ratio of palladium to ruthenium is (3 to 6):1, The method according to item 4, characterized in that.

[0018] 8. In step (3), the mass ratio of the catalyst carrier in step (1) to the catalyst precursor i in step (2) is 1:(2 to 5), The method according to item 4, characterized in that.

[0019] 9. The reducing agent in step (4) is at least one selected from the group consisting of hydrogen, hydrazine hydrate, formaldehyde, formic acid, salts of formaldehyde, or formates, preferably hydrazine hydrate, The method according to item 4, characterized in that.

[0020] 10. Use of the catalyst according to any one of items 1 to 3 in the hydrogenation purification reaction of crude terephthalic acid, Use by subjecting crude terephthalic acid to the hydrogenation purification reaction in the presence of the catalyst to obtain purified terephthalic acid.

[0021] Compared with the prior art, the present disclosure can achieve the following advantages.

[0022] (1) The catalyst for hydrogenating and purifying crude terephthalic acid according to the present disclosure contains Pd and Ru as active components. In particular, Ru 4+ and Ru 0 The weight ratio of is controlled within a specific range of (0.1 to 1.0). Therefore, good anti-sintering performance can be obtained.

[0023] (2) The method for preparing a catalyst for hydrogenating and purifying crude terephthalic acid according to the present disclosure is easy to operate. By selecting raw materials and processing conditions, Ru 4+ and Ru 0 are introduced into the catalyst, and their weight ratio is effectively controlled to ensure obtaining the above-mentioned catalyst for hydrogenating and purifying crude terephthalic acid.

[0024] (3) When the catalyst according to the present disclosure is used in the hydrogenation purification reaction of crude terephthalic acid, it shows the advantage of high thermal stability to ensure catalyst performance, thereby achieving excellent technical effects.

[0025] [Description of the Drawings] Figure 1 is an XPS pattern showing Pd 0 in the 3d zone of the catalyst prepared in Example 1; Figure 2 is an XPS pattern showing Ru 4+ in the 3p zone of the catalyst prepared in Example 1.

[0026] [Detailed Description] Except in the examples, all numerical values of the parameters in this specification should be understood as being modified by the term "about" in all cases, regardless of whether the term "about" actually appears before the numerical value.

[0027] In one aspect, the present disclosure is a catalyst for hydrogenating and purifying crude terephthalic acid, comprising a carrier and an active component, The active component includes palladium and ruthenium, Palladium and ruthenium are in a weight ratio of (3 to 10):1 on an elemental basis, Palladium is Pd 0 and ruthenium is Ru 0 and Ru 4+ and contain, Ru 4+ and Ru 0 and are in a weight ratio of 0.1 to 1.0, regarding the catalyst.

[0028] As used herein, the term "crude terephthalic acid" refers to a terephthalic acid product containing a relatively high concentration of p-carboxybenzaldehyde (4-CBA). In a variant, the crude terephthalic acid contains, for example, at least 1000 ppm, at least 2500 ppm, at least 5000 ppm, or at least 8000 ppm of p-carboxybenzaldehyde. As used herein, the term "hydrogenating and purifying crude terephthalic acid" refers to the process of converting and removing p-carboxybenzaldehyde by reacting crude terephthalic acid with hydrogen. Accordingly, a product having a reduced p-carboxybenzaldehyde content relative to crude terephthalic acid is called "purified terephthalic acid". For example, the purified terephthalic acid may have a p-carboxybenzaldehyde content that is at least 100 ppm, at least 500 ppm, at least 1000 ppm, at least 2500 ppm, at least 5000 ppm, or at least 8000 ppm lower than the p-carboxybenzaldehyde content of the crude terephthalic acid. In a variant, the purified terephthalic acid may have a p-carboxybenzaldehyde content of 25 ppm or less so as to be directly used as a raw material for synthesizing a polyester such as polyethylene terephthalate (PET).

[0029] In one embodiment, the catalyst for hydrogenating and purifying crude terephthalic acid may contain 0.3 to 1 wt% of an active component. The active component may include palladium and ruthenium, and palladium and ruthenium are in a weight ratio of (3 to 10):1, preferably (3 to 6):1 on an elemental basis. In a variant, palladium is Pd 0 and ruthenium is Ru 0 and Ru 4+ and includes Ru 4+ and Ru 0 which are in a weight ratio of 0.1 to 1.0, preferably 0.2 to 0.8.

[0030] In the present disclosure, there is no particular limitation on the distribution of the active component on the carrier. In one embodiment, at least 50%, at least 75%, at least 90%, or at least 95% of the active component may be dispersed on the surface of the carrier. Preferably, the catalyst for hydrogenating and purifying crude terephthalic acid may have a core-shell structure, where the core includes or consists essentially of the carrier, and the shell includes or consists essentially of the active component. In a variant, the catalyst for hydrogenating and purifying crude terephthalic acid may have a core-shell structure, where the core consists essentially of the carrier, and the shell consists essentially of palladium and ruthenium, and palladium and ruthenium are uniformly distributed in the shell. Preferably, the shell may have a thickness of 10 to 200, preferably 40 to 100 microns.

[0031] In one embodiment, the carrier may be one widely used in the art in the catalyst for hydrogenating and purifying crude terephthalic acid. In a variant, the carrier is activated carbon. Preferably, the activated carbon is at least one selected from the group consisting of coal-based activated carbon, wood activated carbon, and nut shell activated carbon. Preferably, the nut shell activated carbon is coconut shell activated carbon. In a variant, the coconut shell activated carbon has a surface area of 800 to 1600 m 2It may have a specific surface area of / g and a pore volume of 0.35 to 0.80 mL / g. Coconut shell activated carbon is commercially available as particles (for example, particles having a size of 4 to 8 mesh).

[0032] In a further aspect, the present disclosure is a method for preparing the above catalyst for hydrogenation purification of crude terephthalic acid, comprising: (1) a step of providing a catalyst support; (2) a step of mixing the catalyst support of step (1) with a source of active metal and an alkylamine, and subjecting the obtained mixture to aging and a first heat treatment to obtain a catalyst precursor; (3) a step of reducing the catalyst precursor of step (2) with a reducing agent to obtain the catalyst. The present disclosure relates to a method comprising the above steps.

[0033] In one embodiment, the step (1) of providing a catalyst support is carried out by pretreating activated carbon to obtain a catalyst support. The activated carbon may be pretreated by any conventional means in the art to obtain a catalyst support. In one embodiment, the pretreatment includes washing and drying. In a variant, the washing is carried out with water, and the volume ratio of water to activated carbon is (2 to 10):1, and the drying is carried out at a temperature of 100 to 130 °C for 4 to 8 hours.

[0034] In one embodiment, before the step of mixing the catalyst support of step (1) with the source of active metal and the alkylamine, the source of active metal and the alkylamine may be mixed with a solvent. In a variant, the solvent, the alkylamine, and the source of active metal are mixed in a mass ratio of (5000 to 30000):(20 to 50):(5 to 20). The obtained mixture may be mixed with the catalyst support of step (1) in a mass ratio of (2 to 5):1.

[0035] The solvent may be any organic solvent widely used in the art. In one embodiment, the solvent is at least one selected from the group consisting of diethyl ether, dimethyl ether, ethanol, isopropanol, and acetone, preferably diethyl ether.

[0036] In one embodiment, step (2) may further include a step of removing the solvent before the first heat treatment. In a variant, the solvent removal may include a step of evaporating and condensing to recover the solvent, and the evaporation temperature is preferably 60 to 90 °C.

[0037] In one embodiment, the source of the active metal may include a source of palladium and a source of ruthenium. In a variant, the source of the palladium is a palladium salt, and the source of the ruthenium is a ruthenium salt. Suitable said palladium salts may be at least one selected from the group consisting of palladium nitrate, palladium acetate, chloropalladic acid, chloropalladate, and tetraammine dichloropalladium, preferably palladium acetate. Suitable said ruthenium salts may be at least one selected from the group consisting of ruthenium nitrate, ruthenium acetate, and ruthenium trichloride, preferably ruthenium acetate.

[0038] In one embodiment, the alkyl group in the alkylamine may be a straight-chain alkyl, preferably selected from the group consisting of C3-C20 straight-chain alkyl groups, more preferably selected from the group consisting of C12-C18 straight-chain alkyl groups. Examples of suitable alkylamines may include, but are not limited to, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine.

[0039] In one embodiment, the aging is carried out for 2 to 24 hours, preferably 4 to 12 hours. In the present disclosure, there is no particular limitation on the aging conditions. Conditions widely used in the art may be used. In a modified example, the aging is carried out in an oxygen-containing atmosphere such as air.

[0040] The first heat treatment may include a step of heat treating at 150 to 250 ° C for 2 to 8 hours in an inert atmosphere. The inert atmosphere may include nitrogen or an inert gas, preferably nitrogen.

[0041] In one embodiment, the reducing agent is at least one selected from the group consisting of hydrazine hydrate, formaldehyde, formic acid, salts of formaldehyde, or formates, preferably hydrazine hydrate. In a modified example, hydrazine hydrate and the catalyst precursor in step (2) are used in a mass ratio of 1: (2 to 10) to reduce the catalyst precursor in step (2) with hydrazine hydrate. Preferably, the reducing step is carried out at room temperature (25 ° C) for 4 to 12 hours, preferably 6 to 9 hours. In one embodiment, after reducing the catalyst precursor in step (2) with the reducing agent, the obtained catalyst may be subjected to a second heat treatment. The second heat treatment may include a step of heat treating at 100 to 200 ° C for 2 to 8 hours in an inert atmosphere. The inert atmosphere may include nitrogen or an inert gas, preferably nitrogen.

[0042] In a further aspect, the present disclosure relates to the use of the above catalyst for hydrogenating and purifying crude terephthalic acid in the hydrogenation purification reaction of crude terephthalic acid. Crude terephthalic acid may be subjected to the hydrogenation purification reaction in the presence of the catalyst to obtain purified terephthalic acid. In a modified example, the hydrogenation purification reaction of crude terephthalic acid may be carried out under reaction conditions including a reaction temperature of 250 to 350 ° C, preferably 270 to 290 ° C, and a reaction pressure of 6.5 to 8.5 MPa. During the hydrogenation purification reaction of crude terephthalic acid, 4-CBA is converted and removed to obtain purified terephthalic acid.

[0043] The catalyst for hydrogenation purification of crude terephthalic acid according to the present disclosure may have a conversion of at least 85%, preferably at least 90%, more preferably 95%, and most preferably 99% with respect to 4-CBA. The catalyst for hydrogenation purification of crude terephthalic acid according to the present disclosure can effectively suppress the grain growth of palladium in the catalyst at high temperatures (for example, 300 °C or higher, 400 °C or higher, and 500 °C or higher). In one embodiment, the catalyst for hydrogenation purification of crude terephthalic acid according to the present disclosure can have a grain growth rate of 25% or less, preferably 10% or less, more preferably 5% or less, with respect to palladium in the catalyst at, for example, 300 °C, 400 °C, or 500 °C. For example, the grain growth rate can be 25%, 20%, 15%, 10%, 5%, 2%, or 1%. In a variant, at 300 °C, the grain growth rate with respect to palladium in the catalyst for hydrogenation purification of crude terephthalic acid according to the present disclosure can be 10% or less, preferably 5% or less, more preferably 3% or less. Generally, the hydrogenation purification reaction is operated under conditions including a reaction pressure of 6.5 to 8.5 MPa and a reaction temperature of 250 to 290 °C. Therefore, under the conditions for the conventional hydrogenation purification reaction, the catalyst for hydrogenation purification of crude terephthalic acid according to the present disclosure can effectively control the grain growth of palladium, and thereby can have excellent anti-sintering performance. Therefore, the catalyst for hydrogenation purification of crude terephthalic acid according to the present disclosure can make the hydrogenation purification reaction of crude terephthalic acid more efficient and stable.

[0044] 〔Examples〕 The features and advantages of the present invention will become apparent from the following examples. The examples are intended to be illustrative and not to limit the present invention in any way.

[0045] <Method for testing> The contents of Pd and Ru in the catalysts of the examples and comparative examples were determined by ICP-AES.

[0046] The content of Ru in different valence states in the catalysts of the examples and comparative examples was analyzed by XPS using an ESCA-IAB MK II photoelectron spectrometer. The test was operated under the conditions of a laser light source (hv - 1486.6 eV) of MgKa line, an operating voltage of 10 kV, an X-ray current of 20 mA, and contaminated carbon C1s (Eb = 284.6 eV) as energy correction. Under these conditions, a pattern of the catalyst was obtained, and Ru 0 corresponding characteristic peak (Ru3p3 / 2 ) at 461.5 eV, and Ru +4 corresponding characteristic peak (Ru3p3 / 2 ) at 465.2 eV were present. The Ru3p3 / 2 peak was fitted and separated using xps peakfit 4.1 software, and then the content ratio of ruthenium in different valence states was calculated using the following formula.

[0047]

Equation

[0048] Here, x is Ru in the valence state being analyzed, I is the area of the photoelectron peak, n is the number of valence states of Ru being considered, and S was the sensitivity coefficient.

[0049] The thermal stability of the catalysts of the examples and comparative examples was tested as follows.

[0050] The catalysts were calcined at 300 °C, 400 °C, and 500 °C for 8 hours respectively under a nitrogen atmosphere and then cooled to room temperature. The calcined catalysts were detected by an X-ray diffractometer (XRD), and the average particle size of palladium contained therein was calculated by using the Debye-Scherrer formula.

[0051] Debye-Scherrer formula: Dhkl = kλ / βcosθ Here, Dhkl is the grain diameter along the direction perpendicular to the crystal plane (hkl), k is the Scherrer constant (usually 0.89), λ is the wavelength of the incident X-ray (the wavelength of CuKa is 0.15406 nm, and the wavelength of CuKa1 was 0.15418 nm), θ is the Bragg diffraction angle (°), and β was the full width at half maximum (FWHM) of the diffraction peak (rad).

[0052] The thermal stability of the catalyst is represented by the grain growth rate of the active component in the catalyst before and after calcination. The larger the value, the lower the stability, and vice versa. The grain growth rate was calculated according to the following formula.

[0053] Grain growth rate = [(average particle diameter of Pd after calcination - average particle diameter of Pd in the fresh catalyst) / average particle diameter of Pd in the fresh catalyst] × 100%.

[0054] The activities of the catalysts of the examples and comparative examples were tested as follows.

[0055] Crude terephthalic acid was subjected to a hydrogenation purification reaction under a nitrogen atmosphere in the presence of the catalysts of the examples and comparative examples under the conditions shown in the following table to obtain purified terephthalic acid. After completely dissolving the crude terephthalic acid and the purified terephthalic acid in aqueous ammonia, they were analyzed by high performance liquid chromatography (HPLC) to obtain their 4-CBA contents. Then, the conversion to 4-CBA was calculated to characterize the activity of the catalyst.

[0056] Conditions for the hydrogenation purification reaction

[0057]

Table 1

[0058] Conversion to 4-CBA = [(4-CBA content in purified terephthalic acid - 4-CBA content in crude terephthalic acid) / 4-CBA content in crude terephthalic acid] × 100%.

[0059] <Example 1> 100 g of (1100 m2 Flake-shaped coconut shell activated carbon with a specific surface area of 4 - 8 mesh (having a pore volume of 0.52 mL / g) was obtained, washed with pure water and pure water with a volume ratio of activated carbon to pure water of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd, Ru, and hexadecylamine were in amounts of 1250 ppm by weight, 250 ppm by weight, and 1.0% by weight, respectively. 100 g of the catalyst support was added to the mixture with a mass ratio of catalyst support to the mixture of 1:4, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, and subjected to a first heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst precursor. 200 g of hydrazine hydrate (having a concentration of 20% by weight) was added to the catalyst precursor, and the reduction step was operated for 8 hours. The mixture was then subjected to a second heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst.

[0060] The content of the active component, the thermal stability and activity of the catalyst were evaluated by the methods described above for the tests. The results are listed in Table 1.

[0061] <Example 2> 100 g of (1100 m 2Flake-shaped coconut shell activated carbon with a size of 4 - 8 mesh (having a specific surface area of 1100 m² / g and a pore volume of 0.52 mL / g) was obtained, washed with pure water and pure water with a volume ratio of activated carbon to pure water of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd, Ru, and tetradecylamine were in amounts of 1250 ppm by weight, 250 ppm by weight, and 1.0% by weight, respectively. 100 g of the catalyst support was added to the mixture with a mass ratio of catalyst support to the mixture of 1:4, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, and subjected to a first heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst precursor. 200 g of hydrazine hydrate (having a concentration of 20% by weight) was added to the catalyst precursor, and the reduction step was run for 9 hours. The mixture was then subjected to a second heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst.

[0062] The content of the active component, the thermal stability and activity of the catalyst were evaluated by the methods for the above-described tests. The results are listed in Table 1.

[0063] <Example 3> 100 g of (1100 m 2Flake-shaped coconut shell activated carbon with a size of 4 to 8 mesh and having a specific surface area of / g and a pore volume of 0.52 mL / g was obtained, washed with pure water and pure water with a volume ratio of activated carbon to pure water of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd, Ru, and hexadecylamine were in amounts of 1250 ppm by weight, 250 ppm by weight, and 1.0% by weight, respectively. 100 g of the catalyst support was added to the mixture with a mass ratio of catalyst support to the mixture of 1:4, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, and subjected to a first heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst precursor. 200 g of hydrazine hydrate (having a concentration of 20% by weight) was added to the catalyst precursor, and the reduction step was operated for 7 hours. The mixture was then subjected to a second heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst. The obtained catalyst was calcined at 300 °C, 400 °C, and 500 °C for 8 hours each under a nitrogen atmosphere to evaluate the thermal stability of the catalyst.

[0064] The content of the active component, the thermal stability and activity of the catalyst were evaluated by the methods described above for the tests. The results are listed in Table 1.

[0065] <Example 4> 100 g of (1100 m 2Flake-shaped coconut shell activated carbon with a specific surface area of 4 to 8 mesh (having a pore volume of 0.52 mL / g) was obtained, washed with pure water at a volume ratio of 5:1 of pure water to activated carbon, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd, Ru, and hexadecylamine were each in amounts of 1250 ppm by weight, 250 ppm by weight, and 1.0% by weight, respectively. 100 g of the catalyst support was added to the mixture at a mass ratio of 1:4 of the catalyst support to the mixture, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, and subjected to a first heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst precursor. 200 g of hydrazine hydrate (having a concentration of 20% by weight) was added to the catalyst precursor, and the reduction step was operated for 6 hours. The mixture was then subjected to a second heat treatment at 180 °C for 4 hours under a nitrogen atmosphere and cooled to room temperature to obtain a catalyst.

[0066] The content of the active component, the thermal stability and activity of the catalyst were evaluated by the method for the above-described tests. The results are listed in Table 1.

[0067] <Comparative Example 1> 100 g of (1100 m 2Flake-shaped coconut shell activated carbon with a size of 4-8 mesh (having a specific surface area of / g and a pore volume of 0.52 mL / g) was obtained, washed with pure water having a volume ratio of pure water to activated carbon of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd and hexadecylamine were in amounts of 1250 ppm by weight and 1.0% by weight, respectively. 100 g of the catalyst support was added to the mixture in a mass ratio of catalyst support to the mixture of 1:4, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, and cooled to room temperature to obtain a catalyst precursor. The catalyst precursor was subjected to a first heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst precursor. 200 g of hydrazine hydrate (having a concentration of 20% by weight) was added to the catalyst precursor, and the reduction step was operated for 8 hours. The mixture was then subjected to a second heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst. The content of the active component, the thermal stability and activity of the catalyst were evaluated by the method for the above-described tests. The results are listed in Table 1.

[0068] <Comparative Example 2> 100 g of (1100 m 2 Flake-shaped coconut shell activated carbon with a size of 4-8 mesh (having a specific surface area of / g and a pore volume of 0.52 mL / g) was obtained, washed with pure water having a volume ratio of pure water to activated carbon of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd, Ru, and hexadecylamine were in amounts of 1250 ppm by weight, 250 ppm by weight, and 1.0% by weight, respectively. 100 g of the catalyst support was added to the mixture in a mass ratio of catalyst support to the mixture of 1:4, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, and cooled to room temperature to obtain a catalyst precursor. The catalyst precursor was subjected to a second heat treatment at 400 °C for 8 hours under a hydrogen atmosphere, cooled to room temperature to obtain a catalyst.

[0069] The content of the active ingredient, the thermal stability and activity of the catalyst were evaluated by the methods for the above-described tests. The results are listed in Table 1.

[0070] <Comparative Example 3> 100 g of (1100 m 2 Flaky coconut shell activated carbon with a size of 4 - 8 mesh having a specific surface area of / g and a pore volume of 0.52 mL / g was obtained, washed with pure water and pure water with a volume ratio of activated carbon to pure water of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd, Ru, and hexadecylamine were in amounts of 1250 weight ppm, 250 weight ppm, and 1.0 weight %, respectively. 100 g of the catalyst support was added to the mixture with a mass ratio of catalyst support to the mixture of 1:4, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, and subjected to a first heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a catalyst precursor. 200 g of hydrazine hydrate (having a concentration of 2 wt%) was added to the catalyst precursor, and the reduction step was operated for 3 hours. The mixture was then subjected to a second heat treatment at 180 °C for 4 hours under a nitrogen atmosphere and cooled to room temperature to obtain a catalyst.

[0071] The content of the active ingredient, the thermal stability and activity of the catalyst were evaluated by the methods for the above-described tests. The results are listed in Table 1.

[0072] <Comparative Example 4> 100 g of (1100 m 2Flaky coconut shell activated carbon with a size of 4 - 8 mesh (having a specific surface area of [X] m² / g and a pore volume of 0.52 mL / g) was obtained, washed with pure water at a volume ratio of pure water to activated carbon of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was stirred for 30 minutes. Pd, Ru, and hexadecylamine were in amounts of 1250 ppm by weight, 250 ppm by weight, and 1.0% by weight, respectively. 100 g of the catalyst support was added to the mixture with a mass ratio of catalyst support to the mixture of 1:4, and then subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, cooled to room temperature, and a catalyst precursor was obtained. 200 g of hydrazine hydrate (having a concentration of 20% by weight) was added to the catalyst precursor, and the reduction process was carried out for 12 hours. The mixture was then subjected to a second heat treatment at 180 °C for 4 hours under a nitrogen atmosphere, cooled to room temperature, and a catalyst was obtained.

[0073] The content of the active component, the thermal stability and activity of the catalyst were evaluated by the methods described above for the tests. The results are listed in Table 1.

[0074] <Comparative Example 5> 100 g of (1100 m 2 Flaky coconut shell activated carbon with a size of 4 - 8 mesh (having a specific surface area of [X] m² / g and a pore volume of 0.52 mL / g) was obtained, washed with pure water at a volume ratio of pure water to activated carbon of 5:1, and then dried at 130 °C for 8 hours to obtain a catalyst support. 400 g of a mixture of palladium acetate, ruthenium acetate, and diethyl ether was stirred for 30 minutes. Pd and Ru were in amounts of 1250 ppm by weight and 250 ppm by weight, respectively. 100 g of the catalyst support was added to the mixture with a mass ratio of catalyst support to the mixture of 1:4, and then the resulting mixture was subjected to aging for 8 hours, evaporated and condensed at 80 °C to recover diethyl ether, cooled to room temperature, and a catalyst precursor was obtained. The catalyst precursor was subjected to a second heat treatment at 80 °C for 8 hours under a hydrogen atmosphere, cooled to room temperature, and a catalyst was obtained. Note: In the original text, there are some missing values marked as [X] in the English translation, which should be filled according to the actual content in the original Chinese text. Also, the 2 and - tags are preserved as they are without any change as required.

[0075] The content of the active ingredient, the thermal stability and activity of the catalyst were evaluated by the methods for the above-described tests. The results are listed in Table 1.

[0076] <Comparative Example 6> In this example, Example 1 of CN102039123A was repeated.

[0077] 50 g of granular coconut shell activated carbon support was pretreated by immersing it in 400 ml of 0.01% dilute nitric acid solution for 4 hours, then washing it with deionized water until neutral, draining, drying at 105°C for 24 hours, and naturally cooling to room temperature.

[0078] Chloroplatinic acid, ruthenium trichloride hydrate, and tartaric acid were dissolved in 20 ml of deionized water. A pure aqueous solution of hydroxymethylcellulose was added thereto. The resulting solution was adjusted to a pH of 3.0 with 8% sodium carbonate and finally adjusted to a volume of 40 ml to obtain palladium colloid. The palladium colloid

[0079]

Table 2

[0080] contained (by weight ratio).

[0081] The support was placed in a rotary plate, and the prepared palladium colloid was sprayed onto the support within 5 minutes. The support was allowed to stand for more than 8 hours, then reduced with hydrogen at 200°C for 6 hours, naturally cooled to room temperature under a hydrogen atmosphere, and finally washed with pure water until no Cl - remained to obtain a catalyst Cat1 for hydrogenating and purifying terephthalic acid.

[0082] The content of the active ingredient of Cat1 was evaluated by the method for the above-described test. The results showed that the catalyst consisted of palladium in a valence state of 0 and ruthenium in a valence state of 3. Furthermore, the thermal stability and activity of Cat1 were evaluated by the method for the above-described test. The results are listed in Table 1.

[0083] [Table 3]

Brief Description of the Drawings

[0084]

Figure 1

Figure 2

Claims

1. A catalyst for hydrogenating and purifying crude terephthalic acid, comprising a carrier and an active ingredient, wherein the active ingredient contains palladium and ruthenium, and the weight ratio of palladium to ruthenium is (3 - 10):1 on an elemental basis. Palladium is Pd ０ whereas ruthenium is Ru ０ and Ru ４＋ and, includes Ru ４＋ and Ru ０ and are in a weight ratio of 0.1 to 1.0, the catalyst.

2. The carrier is activated carbon, preferably, the activated carbon is at least one selected from the group consisting of coal-based activated carbon, wood activated carbon, and nut shell activated carbon. The catalyst according to claim 1, characterized in that.

3. Having a core-shell structure, wherein the core consists essentially of the carrier, and the shell consists essentially of the active ingredient, preferably, the shell has a thickness of 10 - 200 microns, preferably, palladium and ruthenium are uniformly distributed in the shell. The catalyst according to claim 1, characterized in that.

4. Having a grain growth rate of palladium of 10% or less, preferably 5% or less, more preferably 3% or less at 300 °C. The catalyst according to claim 1, characterized in that.

5. A method for preparing the catalyst according to any one of claims 1 to 4, comprising: (1) providing a catalyst carrier; (2) mixing the catalyst carrier of step (1) with a source of active metal and an alkylamine, and subjecting the resulting mixture to aging and a first heat treatment to obtain a catalyst precursor; (3) reducing the catalyst precursor of step (2) with a reducing agent to obtain the catalyst. The method comprising.

6. Before the step of mixing the catalyst carrier of step (1) with the source of active metal and the alkylamine, a step of mixing the source of active metal and the alkylamine with a solvent, further comprising, step (2) further comprises a step of removing the solvent before the first heat treatment. The method according to claim 5, characterized in that.

7. Further comprising a step of subjecting to a second heat treatment after the reducing step (3). The method according to claim 5, characterized in that.

8. The alkyl group in the alkylamine is selected from the group consisting of C3 - C20 alkyl groups. The method according to claim 5, characterized in that.

9. The source of active metal comprises a source of palladium and a source of ruthenium, preferably, comprising a palladium salt and a ruthenium salt. The palladium salt is at least one selected from the group consisting of palladium nitrate, palladium acetate, chloropalladic acid, chloropalladate, and tetraammine dichloropalladium, preferably palladium acetate, The ruthenium salt is at least one selected from the group consisting of ruthenium nitrate, ruthenium acetate, and ruthenium trichloride, preferably ruthenium acetate, The method according to claim 5, characterized in that.

10. In step (2), the mass ratio of the solvent, the alkylamine, and the active metal is (5000 to 30000):(20 to 50):(5 to 20). The method according to claim 6, characterized in that.

11. The reducing agent is at least one selected from the group consisting of hydrazine hydrate, formaldehyde, formic acid, salts of formaldehyde, and formates, preferably hydrazine hydrate, Preferably, hydrazine hydrate and the catalyst precursor in step (2) are used in a mass ratio of 1:(2 to 10) to reduce the catalyst precursor in step (2) with hydrazine hydrate. Preferably, the reduction is carried out at room temperature for 4 to 12 hours, preferably 6 to 9 hours. The method according to claim 5, characterized in that.

12. Use of the catalyst according to any one of claims 1 to 4 in the hydrogenation purification reaction of crude terephthalic acid.

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