KR20090037949A - Supported pd/c catalyst and the preparation method thereof - Google Patents

Abstract

A supported Pd/C catalyst, wherein the Pd supported to the active carbon carrier is present in the microcrystalline state, and the microcrystallines whose diameters are less than 2.5nm take up more than 80wt% of the total amount of the Pd microcrystallines. The preparation method of the supported Pd/C catalyst, wherein the solution for impregnating or spraying the active carbon carrier contains Pd compound and compound with formula I, wherein n, m or l is independently selected from the integers of 0 and 1~5, and R1, R2 or R3 is independently selected from the group consists of H, CH3, NH2, OH and COOH.

Description

SUPPORTED PD / C CATALYST AND THE PREPARATION METHOD THEREOF

The present invention relates to metal palladium catalysts (hereinafter referred to as palladium / carbon catalysts) supported on activated carbon and methods for their preparation, in particular palladium / carbon catalysts used for the purification of crude terephthalic acid by selective hydrogenation and methods for their preparation. .

Cross-reference to related applications

This application claims the benefit of Chinese Patent Application No. 200610029964.4, filed August 11, 2006, the entire contents of which are hereby incorporated by reference for all purposes.

Background of the Invention

Palladium / carbon catalysts are widely used for the selective hydrogenation of unsaturated organic compounds. In particular, palladium / carbon catalysts are useful for the purification of crude terephthalic acid, in which some impurities in the crude terephthalic acid, for example 4-carboxybenzaldehyde (4-CBA), are converted to other compounds via hydrogenation, followed by terephthalic acid products. Can be isolated through crystallization. Since the palladium / carbon catalyst typically contains a single active ingredient, studies known in the art for the improvement of such catalysts have mainly focused on the structure of the support and the distribution of metal Pd on the support and these embodiments. Actually greatly affects the properties of the catalyst.

Since the hydrorefining reaction of terephthalic acid is a primary reaction and the reaction rate is fast, it is difficult for the reactants to diffuse into the catalyst particles during the reaction, and thus the active ingredient inside the catalyst particles cannot function well. Thus, in order to make full use of the precious metal, the catalyst is generally prepared as an eggshell type in which the active ingredient, ie the precious metal is mainly supported on the surface of the support.

The hydrogenation reaction is generally carried out on the surface of the metal Pd in the case of a catalyst having the same metal Pd loading, so that the greater the degree of dispersion of the metal Pd in the catalyst and / or the higher the content of the supported metal Pd crystallites in the catalyst and And / or the better the thermal stability of the catalyst, the higher the activity of the catalyst and the longer the service life of the catalyst.

When a solution containing a Pd compound (eg sodium chloropalladate or palladium chloride) is loaded directly onto activated carbon, a very thin, glossy layer of metal palladium will appear rapidly on the surface of the activated carbon. This is mainly due to the fact that the surface of the activated carbon has reducing groups such as aldehyde groups and free electrons (they will readily reduce Pd ions to zero metal Pd). As a result, the catalyst prepared as above has a very low dispersion metal Pd. One approach to overcome this problem is to convert Pd ions in the Pd compound containing impregnating liquid into insoluble compounds prior to the impregnation. For example, the water soluble Pd compound can be hydrolyzed at room temperature with insoluble Pd (OH) ₂ or PdO.H ₂ O, which is then supported on activated carbon, followed by a reducing agent such as formaldehyde, sodium formate, Reduced to glucose, formic acid or hydrogen gas. In this way, migration of Pd and growth of palladium crystallites can be prevented. For example, USP 3,138,560 teaches that hydrogen peroxide is added to the impregnation solution to hydrolyze the water soluble Pd compound into an insoluble compound, followed by impregnation. USP 4,476,242 suggests the preparation of Pd compound-containing impregnation liquids using organic solvents such as methanol, pyridine and the like. It is also said to be very effective in preventing Pd from moving and making palladium crystallites larger. In addition, there are patents reporting the conversion of chloropallaic acid solution into a Pd-containing colloidal solution by adjusting the pH value, which can prevent reducing groups on the activated carbon surface from directly reducing Pd ions to zero-valent metal Pd. It is said.

CN 1698952A discloses the addition of nitrogen containing polycarboxylic acids to the impregnation liquid used in the preparation of the palladium / carbon catalyst.

Summary of the Invention

It is an object of the present invention to provide a novel palladium catalyst supported on activated carbon. The metal Pd in the catalyst has greater dispersity, more crystallite content, and better thermal stability. The catalyst can provide high conversion of 4-carboxybenzaldehyde (4-CBA) when used in hydrogenation purification of crude terephthalic acid.

Still another object of the present invention is to provide a method for preparing the palladium / carbon catalyst.

In a first aspect, the present invention provides that the palladium supported on the activated carbon support is present as nano-sized crystals, and crystallites having a particle size of less than 2.5 nm are at least 80% by weight, preferably at least 85% by weight of the total palladium crystallites. , More preferably at least 88% by weight, and most preferably at least 90% by weight.

In the palladium / carbon catalyst according to the invention, the content of metal Pd is preferably in the range of 0.05 to 5% by weight, more preferably in the range of 0.2 to 3.5% by weight, based on the total weight of the catalyst.

In a preferred embodiment, the supported palladium comprises palladium crystallites in a 5 nm deep layer below the surface of the activated carbon support when the palladium / carbon catalyst has a Pd content of 0.50 ± 0.10% by weight of the total weight of the catalyst. At least 30% by weight, preferably at least 40% by weight, more preferably at least 50% by weight of the total weight of all atoms in the atom; The palladium crystallites in the 300 nm depth layer below the surface of the activated carbon support are at least 5% by weight, preferably at least 10% by weight, more preferably at least 15% by weight, most preferably 20 of the total weight of all atoms in the layer. Concentrate on the surface layer of the activated carbon support to account for at least weight percent.

In the palladium / carbon catalyst according to the invention, the supported palladium is highly dispersed on the surface of the activated carbon support, with a degree of dispersion of at least 5%, preferably at least 10%, more preferably at least 15%, most Preferably it is 20% or more. After calcining the catalyst for 10 hours at 500 ° C. under a nitrogen stream foamed through water (at 25 ° C.), the supported palladium is 10 nm or less, preferably 8.0 nm or less, more preferably 7.0 nm or less Most preferably has an average particle size of 6.0 nm or less.

In the second aspect, the present invention

a) washing activated carbon with an aqueous solution of an inorganic acid, followed by neutral washing with water, and then drying the washed activated carbon to provide an activated carbon support;

b) impregnating or spraying the activated carbon support with a Pd compound and an aqueous solution containing an additive to support the Pd compound on the activated carbon support to provide a catalyst precursor, wherein the molar ratio of additive in the solution to Pd in the Pd compound Is in the range of 0.01: 1 to 2.0: 1; the additive is selected from compounds represented by Formula I, and the palladium containing solution is adjusted to a pH value of 7 ± 3):

Where

n, m and l are independently 0 or an integer from 1 to 5;

R ₁ , R ₂ and R ₃ are independently selected from the group consisting of H, CH ₃ , NH ₂ , OH and COOH); And

c) treating said catalyst precursor with a reducing agent to provide a palladium / carbon catalyst

It provides a method for producing the palladium / carbon catalyst comprising a.

In a preferred embodiment, the method further comprises aging the catalyst precursor for 1 to 50 hours at a temperature of 0 to 80 ° C. before the reduction treatment of the catalyst precursor.

There is no particular limitation on the activated carbon used in the present invention. An example of such activated carbon is coconut shell activated carbon having a specific surface area of greater than 900 m 2 / g and particle size in the range of 4 to 8 mesh.

Aqueous solutions of inorganic acids useful in the process according to the invention may have an acid concentration of 0.01 to 5 M (mol / liter), preferably 0.01 to 3.0 M. Examples of such inorganic acids include, but are not limited to hydrochloric acid, nitric acid and phosphoric acid. The time period for the acid wash is not critical but is preferably in the range of 0.5 to 8 hours, more preferably 0.5 to 4 hours.

The activated carbon is washed with an aqueous solution of inorganic acid, then neutrally washed with water and then dried. The drying is generally carried out at a temperature of 80 to 150 ° C. for 0.5 to 10 hours, preferably 0.5 to 6 hours.

Examples of Pd compounds useful in the present invention include, but are not limited to, palladium halides, palladium acetate, palladium nitrate, chloropallaic acid, basic salts of chloropallaic acid, palladium amino-complexes, and mixtures thereof. Preferably, the Pd compound is chloropallaic acid or palladium acetate. The solution containing the Pd compound and the additive preferably has a pH k ° of 4-9. The concentration of the Pd compound represented by Pd in the solution is preferably in the range of 0.01 to 20% by weight, more preferably in the range of 0.1 to 10% by weight, and most preferably in the range of 0.2 to 3.6% by weight.

The amount of the additive used in the Pd-containing solution may vary depending on the Pd compound used and the additive used. In general, however, a molar ratio of additive to Pd in the solution in the range of 0.01: 1 to 2: 1 is suitable, and the molar ratio of Pd in the additive to Pd compound is preferably between 0.05: 1 and 1.5: 1. Range, more preferably 0.1: 1 to 1.0: 1.

Some examples of compounds of formula I useful in the present invention are as follows:

Formula I

Additive A R ₁ = R ₂ = R ₃ = H n = m = l = 0 Additive B R ₁ = R ₃ = H; R ₂ = NH ₂ n = 5; m = l = 1 Additive C R ₁ = CH ₃ ; R ₂ = R ₃ = H n = 4; m = l = 0 Additive D R ₁ = R ₂ = H; R ₃ = OH n = m = 3; l = 1 Additive E R ₁ = R ₃ = H; R ₂ = COOH n = m = l = 0 Additive F R ₁ = R ₃ = H; R ₂ = OH n = m = l = 0

Examples of reducing agents used to reduce the catalyst precursors include, but are not limited to, formic acid, sodium formate, formaldehyde, hydrazine hydrate, glucose, hydrogen gas, and mixtures thereof. Preferably, the reducing agent is sodium formate or hydrazine hydrate. The amount of reducing agent used depends on the amount of active ingredient Pd and is generally in the range of 1 to 10 times, preferably 2 to 5 times the theoretical amount required by the reduction reaction. The reduction treatment of the catalyst precursor can be carried out according to methods and conditions well known by those skilled in the art. For example, the reduction treatment may be carried out at a temperature of 0 to 200 ° C, preferably 20 to 120 ° C for 0.5 to 24 hours, preferably 1 to 10 hours, and more preferably 1 to 4 hours. .

In a preferred embodiment, the process for preparing the palladium / carbon catalyst according to the present invention comprises the following steps:

i) washing the particulate or shaped activated carbon support with an aqueous solution of acid for 0.5 to 8 hours, wherein the aqueous solution of acid has an acid concentration of 0.01 to 3.0 mol / liter, the acid consisting of hydrochloric acid, nitric acid and phosphoric acid At least one acid selected from);

ii) neutrally washing the acid washed activated carbon support with water, and then drying it at a temperature of 80 to 150 ° C. for 0.5 to 10 hours to provide a treated activated carbon support;

iii) impregnating or spraying the treated activated carbon support with an aqueous solution containing a water-soluble Pd compound and an additive of formula (I) to support the Pd compound on the treated activated carbon support to provide a catalyst precursor, wherein The amount of Pd compound represented by Pd in the aqueous solution is in the range of 0.1 to 10% by weight, the molar ratio of the additive to Pd is in the range of 0.05: 1 to 1.5: 1, and the aqueous solution is adjusted to a pH value of 7 ± 3). :

Formula I

Where

n, m and l are independently 0 or an integer from 1 to 5;

R ₁ , R ₂ and R ₃ are independently selected from the group consisting of H, CH ₃ , NH ₂ , OH and COOH;

iv) aging the catalyst precursor obtained from step iii) at a temperature of 0 to 80 ° C. for 1 to 50 hours; And

v) treating the aged catalyst precursor with a reducing agent to reduce Pd ions in the Pd compound to metal Pd to provide a palladium / carbon catalyst.

Compared with the prior art, the present invention has the advantage that the prepared catalyst has higher dispersity and more crystallite content of the metal Pd, and the catalyst shows high activity and long service life.

The following examples are provided to further illustrate the invention, but these examples do not limit the invention in any way.

In the examples, the following test methods were used:

(1) Dispersion of Metal Palladium:

The degree of dispersion of the metal palladium was measured by a hydrogen-oxygen titration method using a chemisorption apparatus. The dispersion degree was calculated according to the following formula:

Dispersion = ((2 x V _{ads .} X M _Pd ) / (3 x 22400 x W _sample x C _Pd )) x 100%

In the above,

V _{ads .} Represents the amount of hydrogen gas adsorbed by the sample,

M _Pd represents the atomic weight of Pd,

W _sample represents the weight of the sample,

C _Pd represents the content of _Pd in the sample.

(2) crystallite content:

As used herein, the term "crystallite content" is intended to mean the content of crystallites having a particle size of less than 2.5 nm.

The content of palladium in the catalyst was measured by X-ray fluorescence spectroscopy and the particle size of the metal Pd crystallites was measured by X-ray diffractometer (XRD). The crystallite content was then calculated as follows:

Crystallite content = ((weight of metal Pd crystallites having a particle size of less than 2.5 nm) / (total weight of metal Pd)) x 100%

(3) thermal stability:

The average particle diameter of the Pd crystallites of the palladium / carbon catalyst was measured through an X-ray diffractometer (XRD). After the catalyst was calcined at 500 ° C. for 10 hours under a nitrogen stream foamed through water (at 25 ° C.), the average particle diameter of the Pd crystallites was measured again via an X-ray diffractometer (XRD). The change in the average particle diameter of the Pd crystallites before and after the calcination as well as the average particle diameter of the Pd crystallites after calcination indicates the thermal stability of the catalyst. The smaller the average particle diameter of the Pd crystallites, the better the thermal stability of the catalyst. Further, the smaller the change in the average particle diameter of the Pd crystallites before and after the calcination, the better the thermal stability of the catalyst.

(4) Pd content in layers of varying depths below the catalyst surface

The surface of the catalyst was argon corroded. After corrosion to a certain depth, the content of Pd in the surface layer exposed by the corrosion is measured by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), thus varying the surface below the catalyst surface. The Pd content in the layer at depth was obtained.

Example 1

100 g of coconut shell activated carbon, which had passed through the 4 mesh sieve but remained on the 8 mesh sieve and had a specific surface area of 1100 m 2 / g, was washed with 200 ml of an aqueous 0.4M nitric acid solution for 2 hours. After removal of the acid solution, the activated carbon was washed neutral with deionized water and then dried at 120 ° C. for 6 hours.

Deionized water was added to 3.2 g of an aqueous solution of chloropallaic acid containing 16% by weight of palladium until the total volume was 40 ml. To the solution was then added 2.16 g of a 10 wt% solution of additive A in water and then deionized water until the total volume of the solution reached 60 ml. A 3% NaOH aqueous solution was added to adjust the pH value of the Pd-containing solution to about 7. After aging for 180 minutes, the treated activated carbon was impregnated for 3 hours using the Pd containing solution to provide a catalyst precursor. The catalyst precursor was aged at room temperature for 24 hours and then impregnated at 20 ° C. for 3 hours in a reducing liquid consisting of 20 g of a 5 wt% aqueous solution of hydrazine hydrate and 200 g of pure water. After the liquid was removed by filtration, the solid was neutrally washed with pure water and then dried to give the crystalline product.

Examples 2 to 24

The procedure described in Example 1 was carried out except that a Pd containing solution was prepared using different Pd compounds and different additives. The Pd compound used, the content of Pd compound represented by Pd in the Pd containing solution, the additive used and the molar ratio of additive to Pd are shown in Table 1 below.

Examples 25-30

Using the procedure described in Example 1 above, using different additives (additives used are shown in Table 1), a Pd containing solution was prepared, and the Pd containing solution was sprayed onto activated carbon to provide a catalyst precursor. Using the inorganic acid, concentration of the inorganic acid, acid washing period, drying period, temperature, pH value of the solution containing the additive and the Pd compound, reducing agent, temperature for reducing treatment and period for reducing treatment as shown in FIG. Except it was performed.

Comparative Example

The procedure disclosed in Example 1 was performed except that no additive was used in preparing the Pd-containing solution.

Dispersion, crystallite content, thermal stability, and the tip

Pd content in layers of varying depths below every surface was measured on the catalysts prepared in the examples and comparative examples. The catalysts were further evaluated under the evaluation conditions as shown below. The results are shown in Tables 3 and 4 below.

Evaluation conditions for the catalysts: Amount of catalyst 2.0 g Amount of crude terephthalic acid 30.0 g Amount of 4-CBA 1.0 g Reaction pressure 70 kg Partial pressure of hydrogen gas 5.0 kg Reaction time 1.0 hours Reaction temperature 270 ℃

Conversion rate of 4-CBA = (amount of 4-CBA added-amount of residue) / amount of 4-CBA added x 100

Example Pd compound additive Charged Pd / Activated Carbon (% by weight) Additive / Pd (mol / mol) Example 1 Chloropallaic acid Additive A 0.51 0.20 Example 2 Chloropallaic acid Additive A 0.51 0.30 Example 3 Chloropallaic acid Additive A 0.22 0.60 Example 4 Palladium acetate Additive A 0.08 1.50 Example 5 Chloropallaic acid Additive B 0.51 0.20 Example 6 Chloropallaic acid Additive B 0.62 0.40 Example 7 Chloropallaic acid Additive B 0.51 0.60 Example 8 Palladium acetate Additive B 3.55 0.80 Example 9 Chloropallaic acid Additive C 0.51 0.20 Example 10 Chloropallaic acid Additive C 0.51 0.40 Example 11 Chloropallaic acid Additive C 0.51 0.60 Example 12 Palladium acetate Additive C 0.15 1.00 Example 13 Chloropallaic acid Additive D 0.51 0.20 Example 14 Chloropallaic acid Additive D 0.41 0.40 Example 15 Chloropallaic acid Additive D 0.51 0.60 Example 16 Palladium acetate Additive D 0.51 0.80 Example 17 Chloropallaic acid Additive E 0.51 0.20 Example 18 Chloropallaic acid Additive E 1.00 0.40 Example 19 Chloropallaic acid Additive E 0.51 0.60 Example 20 Palladium acetate Additive E 0.51 0.80 Example 21 Chloropallaic acid Additive F 4.50 0.05 Example 22 Chloropallaic acid Additive F 0.51 0.40 Example 23 Chloropallaic acid Additive F 0.51 0.60 Example 24 Palladium acetate Additive F 0.51 0.80 Example 25 Chloropallaic acid Additive A 0.51 0.20 Example 26 Chloropallaic acid Additive B 0.51 0.40 Example 27 Chloropallaic acid Additive C 0.51 0.60 Example 28 Chloropallaic acid Additive D 0.51 0.80 Example 29 Chloropallaic acid Additive E 0.51 0.50 Example 30 Chloropallaic acid Additive F 0.51 0.50 Comparative Example Chloropallaic acid Of 0.51 Of

Example 25 Example 26 Example 27 Example 28 Example 29 Example 30 Inorganic acids Hydrochloric acid nitric acid Phosphoric Acid nitric acid nitric acid nitric acid Concentration of inorganic acid 0.4 0.1 3 0.4 0.01 0.4 Acid wash time 4 8 0.5 4 4 4 Drying temperature 150 120 120 80 120 120 Drying time One 6 6 10 6 6 PH value of solution containing additive and Pd compound 9 7 6 7 4 10 reducing agent Formaldehyde Formaldehyde Sodium formate Hydrogen base Glucose Hydrazine Hydrate Reduction temperature 50 80 120 200 120 80 Reduction time 3 3 2 One 24 3

  Example Pd content in the catalyst (% by weight) Dispersion Degree (%) Crystalline content (%) Average particle size (nm) Average particle size (nm) after calcination at 500 ° C % Change in average particle size before and after calcination % Conversion of 4-CBA Example 1 0.50 20 90 3.5 5.9 69 99.5 Example 2 0.50 23 91 3.6 6.0 67 99.7 Example 3 0.20 29 90 3.4 5.3 56 89.2 Example 4 0.08 21 92 2.7 5.3 96 - Example 5 0.50 20 90 3.5 5.9 69 99.4 Example 6 0.60 26 90 3.6 6.0 67 99.8 Example 7 0.50 28 93 3.8 5.8 53 99.5 Example 8 3.50 20 92 3.3 5.9 79 99.6 Example 9 0.50 20 91 2.9 5.7 97 99.6 Example 10 0.50 22 92 3.8 5.6 47 99.8 Example 11 0.49 25 90 3.6 5.8 61 99.7 Example 12 0.15 28 91 3.0 5.7 90 - Example 13 0.50 20 90 3.6 5.9 64 99.5 Example 14 0.40 21 92 3.3 5.6 70 99.5 Example 15 0.50 26 91 3.4 5.8 71 99.8 Example 16 0.49 25 90 3.2 5.9 84 99.9 Example 17 0.50 30 94 3.6 6.0 67 99.7 Example 18 0.98 27 90 3.7 5.9 59 100 Example 19 0.50 27 91 3.4 5.8 71 99.7 Example 20 0.50 28 91 3.5 5.7 63 99.8 Example 21 4.48 27 90 3.7 6.0 62 100 Example 22 0.50 28 92 3.6 5.9 64 99.7 Example 23 0.50 30 90 3.8 5.9 55 99.9 Example 24 0.50 28 91 3.3 5.9 79 99.7 Example 25 0.50 20 91 3.3 6.0 82 99.6 Example 26 0.50 20 90 3.5 5.9 69 99.7 Example 27 0.50 22 90 3.4 6.0 76 99.8 Example 28 0.49 26 91 3.7 5.9 59 99.9 Example 29 0.50 27 90 3.8 6.0 58 99.8 Example 30 0.50 28 92 3.0 5.7 90 99.6 Comparative Example 0.50 4 52 4.6 11.1 141 66.2

Example Pd content of the catalyst (% by weight) Pd content (wt%) in the 5 nm deep layer below the surface of the catalyst Pd content (wt%) in the 300 nm deep layer below the surface of the catalyst Example 1 0.50 50.2 22.3 Example 2 0.50 51.2 23.7 Example 3 0.20 43.1 11.8 Example 4 0.08 30.1 5.9 Example 5 0.50 52.6 20.4 Example 6 0.60 57.8 28.0 Example 7 0.50 60.1 23.5 Example 8 3.50 63.4 29.3 Example 9 0.50 54.3 24.2 Example 10 0.50 51.4 23.6 Example 11 0.49 50.3 23.2 Example 12 0.15 40.6 11.3 Example 13 0.50 52.3 23.7 Example 14 0.40 50.4 20.5 Example 15 0.50 52.9 24.9 Example 16 0.49 50.4 23.1 Example 17 0.50 56.3 23.0 Example 18 0.98 70.1 30.3 Example 19 0.50 57.8 23.6 Example 20 0.50 53.5 23.8 Example 21 4.48 83.2 40.2 Example 22 0.50 56.1 21.2 Example 23 0.50 50.6 24.7 Example 24 0.50 53.4 25.3 Example 25 0.50 54.5 23.0 Example 26 0.50 55.6 27.4 Example 27 0.50 56.4 23.7 Example 28 0.49 53.3 23.9 Example 29 0.50 50.1 20.1 Example 30 0.50 56.5 24.7 Comparative Example 0.50 30.6 12.5

Patents, patent applications, non-patent literature and test methods cited herein are hereby incorporated by reference.

While the present invention has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the invention is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but will include all embodiments falling within the scope of the appended claims.

Claims (16)

Palladium / carbon catalyst wherein palladium supported on activated carbon support is present as crystallites and crystallites having a particle size of less than 2.5 nm make up at least 80% by weight of the total palladium crystallites. The method of claim 1, When the supported palladium has a Pd content of 0.50 ± 0.10 wt% of the total weight of the catalyst, the carbon-based palladium in the 5 nm deep layer below the surface of the activated carbon support is the total of all atoms in the layer. Account for at least 30% by weight of the weight; Palladium / carbon catalyst concentrated in the surface layer of the activated carbon support such that the metal palladium in the 300 nm depth layer below the surface of the activated carbon support accounts for at least 5% by weight of the total weight of all atoms in the layer. The method of claim 2, When the carbonaceous palladium catalyst has a Pd content of 0.50 ± 0.10% by weight of the total weight of the catalyst, the metal palladium in the 5 nm depth layer below the surface of the activated carbon support is 40% by weight of the total weight of all atoms in the layer Occupy more than; Metal palladium in a 300 nm deep layer below the surface of the activated carbon support comprises at least 10% by weight of the total weight of all atoms in the layer. The method according to any one of claims 1 to 3, The supported palladium is highly dispersed on the surface of the activated carbon support, wherein the dispersion degree is at least 5%. The method of claim 4, wherein Palladium / carbon catalyst having a dispersion of at least 10% of the supported palladium. The method according to any one of claims 1 to 5, A palladium / carbon catalyst wherein the supported palladium has an average grain size of 6.0 nm or less after calcining the catalyst for 10 hours at 500 ° C. under a nitrogen stream foamed through water (at 25 ° C.). The method according to any one of claims 1 to 6, Palladium / carbon catalyst wherein the catalyst comprises from 0.05 to 5 weight percent metal palladium based on the total weight of the catalyst. The method of claim 7, wherein Palladium / carbon catalyst wherein the catalyst comprises 0.2 to 3.5 weight percent metal palladium based on the total weight of the catalyst. a) washing activated carbon with an aqueous solution of an inorganic acid, followed by neutral washing with water, and then drying the washed activated carbon to provide an activated carbon support; b) impregnating or spraying the activated carbon support with a Pd compound and an aqueous solution containing an additive to support the Pd compound on the activated carbon support to provide a catalyst precursor, wherein the molar ratio of additive in the solution to Pd in the Pd compound Is in the range of 0.01: 1 to 2.0: 1; the additive is selected from compounds represented by Formula I: The palladium containing solution is adjusted to a pH value of 7 ± 3: Formula I

Where n, m and l are independently 0 or an integer from 1 to 5; R ₁ , R ₂ and R ₃ are independently selected from the group consisting of H, CH ₃ , NH ₂ , OH and COOH); And c) treating said catalyst precursor with a reducing agent to provide a palladium / carbon catalyst A method for producing a palladium / carbon catalyst according to claim 1. The method of claim 9, The inorganic acid is at least one acid selected from the group consisting of hydrochloric acid, nitric acid and phosphoric acid; The acid wash time ranges from 0.5 to 8 hours; The inorganic acid solution has an acid concentration of 0.01 to 5.0 mol / liter; The drying is carried out at a temperature of 80 to 150 ℃ for 0.5 to 10 hours. The method according to claim 9 or 10, The Pd compound is selected from the group consisting of palladium halides, palladium acetate, palladium nitrate, chloropallaic acid, basic salts of chloropallaic acid, palladium amino-complexes, and mixtures thereof; The palladium concentration in the Pd-containing solution is in the range of 0.01 to 20% by weight; Wherein the molar ratio of additive in the solution to palladium in the Pd compound is in the range of 0.01: 1 to 2.0: 1. The method of claim 11, The Pd compound is chloropallaic acid or palladium acetate; The solution containing the Pd compound and the additive has a pH value of 4 to 9; Palladium concentration in the solution is in the range of 0.1 to 10% by weight; Wherein the molar ratio of additive in the solution to palladium in the Pd compound is in the range of 0.05: 1 to 1.5: 1. The method according to any one of claims 9 to 12, Aging the catalyst precursor at a temperature of 0-80 ° C. for 1-50 hours prior to the reduction treatment. The method according to any one of claims 9 to 13, The reducing agent is selected from the group consisting of formic acid, sodium formate, formaldehyde, hydrazine hydrate, glucose, hydrogen gas, and mixtures thereof; The reduction treatment is carried out at a temperature of from 0 to 200 ° C for 0.5 to 24 hours. The method of claim 14, The catalyst precursor is aged for 1 to 24 hours at a temperature of 0 to 80 ° C. before the reduction treatment; The reducing agent is sodium formate or hydrazine hydrate; The reduction process is carried out at a temperature of 20 to 120 ℃ for 1 to 10 hours. A method for producing a carbonaceous palladium catalyst according to claim 1, i) washing the particulate or shaped activated carbon support with an aqueous solution of acid for 0.5 to 8 hours, wherein the aqueous solution of acid has an acid concentration of 0.01 to 3.0 mol / liter, the acid consisting of hydrochloric acid, nitric acid and phosphoric acid At least one acid selected from); ii) neutrally washing the acid washed activated carbon support with water, and then drying it at a temperature of 80 to 150 ° C. for 0.5 to 10 hours to provide a treated activated carbon support; iii) impregnating or spraying the treated activated carbon support with an aqueous solution containing a water-soluble Pd compound and an additive of formula (I) to support the Pd compound on the treated activated carbon support to provide a catalyst precursor, wherein The amount of Pd compound represented by Pd in the aqueous solution is in the range of 0.1 to 10% by weight, the molar ratio of the additive to Pd is in the range of 0.05: 1 to 1.5: 1, and the aqueous solution is adjusted to a pH value of 7 ± 3). : Formula I

Where n, m and l are independently 0 or an integer from 1 to 5; R ₁ , R ₂ and R ₃ are independently selected from the group consisting of H, CH ₃ , NH ₂ , OH and COOH; iv) aging the catalyst precursor obtained from step iii) at a temperature of 0 to 80 ° C. for 1 to 50 hours; And v) treating the aged catalyst precursor with a reducing agent to reduce Pd ions in the Pd compound to metal Pd to provide a carbonaceous palladium catalyst How to include.