KR20180074286A - PREPARATION METHOD OF Pd/C CATALYST HAVING IMPROVED DURABILITY AND Pd/C CATALYST PREPARATED USING THE METHOD - Google Patents

Abstract

The present invention relates to a method for preparing a palladium/carbon catalyst. According to an embodiment of the present invention, the method for preparing a palladium/carbon catalyst comprises: a first step of preparing a carbon carrier pretreated with acid; a second step of preparing a palladium precursor solution by dissolving a palladium precursor in an acid solution; a third step of generating palladium particles by injecting an oxidizer aqueous solution into the palladium precursor solution of the second step and by stirring the same; a fourth step of injecting the carbon carrier prepared in the first step into the palladium precursor aqueous solution into which the oxidizer aqueous solution is injected; and a fifth step of dipping the palladium particles in the injected carbon carrier.

Description

TECHNICAL FIELD [0001] The present invention relates to a palladium / carbon catalyst having improved durability and a palladium / carbon catalyst prepared therefrom. BACKGROUND ART [0002] Pd /

The present invention relates to a method for synthesizing a palladium catalyst supported on a carbon support, and a method for producing a palladium / carbon catalyst having improved durability.

Palladium / carbon heterogeneous catalysts can be used for various types of reactions, such as reduction of unsaturated hydrocarbons, nitro hydrogenation, benzyl hydrogenation, carbon-carbon bonds and deprotection of cross-linking. Moreover, palladium / carbon catalysts have the advantage of being able to perform simple production processes, high conversion rates, high yield and selectivity, and selective removal of catalyst after reaction completion. As a result, many companies are favored, and they are widely used in petrochemical, fine chemical, and pharmaceutical raw material production processes.

The palladium / carbon catalyst typically comprises 1-50% palladium particles on the surface of the carbon support. The main considerations for preparing palladium / carbon catalysts include the size of the palladium particles, the uniformity of the palladium particles deposited on the carbon surface, the degree of dispersion, and the durability of the palladium / carbon catalyst.

Among these, the durability of the palladium / carbon catalyst is a necessary technique for ensuring the sustainability and stability of the reaction, and various studies for increasing the durability of the palladium / carbon catalyst have been continued.

Korean Patent Publication No. 10-2014-0065686 (2014.05.30)

DISCLOSURE Technical Problem The present invention provides a palladium / carbon hydrotreating catalyst which is easy to mass-produce and has higher durability, and a palladium / carbon hydride catalyst prepared therefrom.

Other objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description.

In order to solve the above problems, the present invention provides, as an embodiment, a method for producing a palladium precursor solution, comprising the steps of preparing a carbon carrier pretreated with an acid, a second step of dissolving the palladium precursor in an acid solution to prepare a palladium precursor solution, A third step of adding an oxidant aqueous solution to the precursor solution and stirring to produce palladium particles, a fourth step of injecting the carbon support prepared in the first step into the aqueous palladium precursor solution into which the oxidant aqueous solution is introduced, And a fifth step of supporting the particles.

Here, the first step includes the steps of: injecting a carbon carrier into an acid solution; stirring the acid solution into which the carbon carrier is injected at 30 ° C to 100 ° C for 30 minutes to 24 hours; Filtration and washing.

In the third step, the oxidant aqueous solution to be added to the palladium precursor solution in the second step may be a predetermined amount.

In order to solve the above problem, the present invention proposes a palladium / carbon catalyst produced by the above-mentioned method and having a reduction rate of palladium particles within 1.5% after a single reaction.

According to the embodiment of the present invention, the mass production is easy and the interaction force between the carrier and the palladium particles is increased, so that the durability of the produced palladium / carbon hydride catalyst is excellent.

The effects of the present invention will be clearly understood and understood by those skilled in the art, either through the specific details described below, or during the course of practicing the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart illustrating a process for preparing a palladium / carbon catalyst according to an embodiment of the present invention. FIG.
FIG. 2 is a graph showing the activity evaluation results of a palladium / carbon catalyst according to the number of times of use of a catalyst of the palladium / carbon catalyst according to Examples and Comparative Examples of the present invention. FIG.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention.

The singular expressions include plural expressions unless the context clearly dictates otherwise. It is to be understood that the terminology used herein is for the purpose of describing the invention, and is in no way intended to limit the invention to the precise form or scope of the invention, and not to limit the presence or addition of one or more other features, integers, Should not be excluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as being consistent with the meanings in the context of the relevant art and are not to be construed as ideal or overly formal meanings unless explicitly defined in the present application.

<Production method of palladium / carbon (Pd / C) catalyst>

Hereinafter, a method for producing a palladium / carbon (Pd / C) catalyst for hydrogenation according to an embodiment of the present invention will be described. However, the present invention is not limited to the following production methods, and the steps of each process may be modified and performed as required.

 The method for preparing a palladium / carbon (Pd / C) catalyst according to an embodiment of the present invention includes a method for improving the durability of a catalyst by a palladium / carbon catalyst preparation method. (S20) preparing a palladium precursor solution by dissolving a palladium precursor in an acid solution (S20), adding an oxidizing agent to increase the pH of the palladium precursor solution (S30 , A step (S40) of injecting a carbon support into the palladium precursor solution into which the oxidizing agent has been introduced, and a step (S50) of supporting palladium on the carbon support.

On the other hand, if necessary, after the carrying step, filtering and washing (S60) the palladium-supported carbon carrier may be further included.

1 is a flowchart showing a process for producing a palladium / carbon catalyst according to an embodiment of the present invention. Hereinafter, each step will be described step by step with reference to the embodiment of FIG.

(1) Prepare a pretreated carbon carrier (hereinafter referred to as the first step).

As a method for improving the durability of the catalyst, a method of pretreating the carbon carrier (acid treatment) is used.

The acid treatment of the carbon support is to increase the functional groups containing oxygen on the surface of the carbon support to increase the interaction with the palladium metal particles. Thereby preventing separation of the palladium particles and improving the durability of the catalyst.

Specifically, activated carbon is adopted as a carbon carrier and is pre-treated with an acid at a temperature of room temperature or higher. As the acid preferred for the process, one of nitric acid, hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, hydrofluoric acid, or a combination of both can be used.

In the pretreatment step, the activated carbon is injected into the acid solution, stirred at a temperature of room temperature or higher, preferably 30 to 100 degrees for 0.5 to 24 hours, filtered and washed several times with distilled water to remove residual acid do.

After washing, the activated carbon is dried in air at a temperature of 50 to 120 degrees or higher for about 1 to 24 hours to complete the pretreated activated carbon.

(2) A palladium precursor solution is prepared by dissolving a palladium precursor in an acid solution (hereinafter referred to as the second step).

In a preferred example of the second step, (1-1) an acid aqueous solution is prepared, (1-2) a palladium precursor is added to the aqueous acid solution in an amount equivalent to the predetermined amount, and then completely dissolved.

In the present invention, the acid solution may be used without limitation in a conventional acid component known in the art. Examples of the acid component include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, or a mixture of at least one of these. Preferably, an aqueous hydrochloric acid solution can be used as the acid solution.

In this case, the concentration of the hydrochloric acid aqueous solution does not greatly affect the process in general, but the dissolution time, temperature, and the amount of the oxidizing agent are changed depending on the concentration of the hydrochloric acid aqueous solution.

Considering the dissolution time, the temperature of the palladium precursor, and the amount of the oxidizing agent, the aqueous hydrochloric acid solution is preferably used in an amount of 5 to 10% by weight. If the aqueous hydrochloric acid solution is less than 5% by weight, dissolution of the palladium precursor becomes too slow, and if it exceeds 10% by weight, the amount of the oxidizing agent may be increased in the subsequent step, which may increase the process time.

The above-described palladium precursor is a compound containing palladium (Pd) and capable of dissociation in an acid solution, and conventional palladium precursors known in the art can be used without limitation. For example, palladium chloride (PdCl ₂ ) or the like can be used.

In this embodiment, the palladium precursor is preferably in the range of 5 to 15% by weight based on the total weight of the carbon support to be added at a later time. When the palladium precursor is less than 5 wt% based on the total weight of the carbon support, the activity of the catalyst is deteriorated because the amount of palladium is too small. When the palladium precursor is more than 15 wt%, the activity of the palladium particles may be lowered.

(3) An oxidizing agent is added to the palladium precursor solution to raise the pH (hereinafter referred to as the third step).

As a preferred example of the second step, (2-1) a predetermined amount of an oxidizing agent is introduced into the solution of the palladium precursor at a time, and (2-2) the solution of the palladium precursor injected with the oxidizing agent is stirred for a certain period of time.

By injecting the oxidizing agent at a time, the palladium metal supported on the carbon support can be miniaturized and highly dispersed. Further, productivity can be improved by shortening the reaction time after the introduction of the oxidizing agent, and industrial mass production is easy.

In this embodiment, it is preferable to use an aqueous solution of sodium hydroxide (NaOH) as the oxidizing agent. The concentration of the sodium hydroxide aqueous solution is preferably 10 to 25% by weight. When the concentration of sodium hydroxide aqueous solution is less than 10% by weight, the amount of water supplied increases and the amount of the palladium / carbon catalyst produced in the reaction tank of a predetermined capacity decreases. If the concentration exceeds 25% by weight, sodium hydroxide may not sufficiently dissolve and may be precipitated .

In this way, the pH of the solution of the palladium precursor is increased and at least one kind of palladium (Pd ⁰ , Pd ²⁺ ) is formed through the injection of an aqueous solution of sodium hydroxide as an oxidizing agent. As the pH is increased, smaller particles of Pd (OH) ₂ are formed and the catalyst has a high activity in a specific reaction.

(4) The carbon support is introduced into the palladium precursor solution into which the oxidizing agent is introduced (hereinafter referred to as the fourth step)

In this embodiment, the carbon carrier uses a carbon carrier pretreated with an acid according to the first step described above.

Also, the average particle diameter, specific surface area and form of the carbon carrier are not particularly limited, and can be appropriately adjusted within the conventional range known in the art.

At this time, the carbon carrier may be introduced into the palladium precursor solution alone or may be mixed with the carbon carrier and water. When the water content of the carbon carrier itself is large, the water may be added without mixing the water. In the case where the water content of the carbon carrier itself is small, water may be mixed and introduced.

(5) The palladium is supported on the carbon carrier (hereinafter referred to as the fifth step).

The supporting temperature is not particularly limited as long as palladium can be supported on the carbon support, but it is preferable that stirring is carried out while maintaining the temperature at 70 to 90 占 폚. When the temperature is lower than 70 ° C, palladium is carried on the carbon carrier at a slower rate or is not supported. When the temperature exceeds 90 ° C, the degree of dispersion of palladium decreases.

(6) The palladium-supported carbon support is filtered and washed (hereinafter referred to as step 6).

In the sixth step, the palladium / carbon catalyst may be filtered and washed by any conventional method known in the art.

As described above, according to the embodiment of the present invention, a palladium / carbon (Pd / C) catalyst having an improved activity while improving the durability of the palladium / carbon catalyst can be produced.

The palladium / carbon catalyst prepared in the present invention may be usefully used as a catalyst for a hydrogenation reaction known in the art, and may be usefully applied to various fields where a palladium catalyst is required.

Next, examples and comparative examples of a method for producing a palladium / carbon catalyst according to an embodiment of the present invention will be described in detail. Hereinafter, the present invention will be described by way of examples only, and the scope of the present invention is not limited by the following examples. The palladium / carbon catalysts of the Examples and Comparative Examples were prepared using a 1 liter laboratory reactor.

[Example]

<Preparation of Carrier>

1) A 1M hydrochloric acid aqueous solution was prepared and charged into a reactor containing 100 g of activated carbon.

2) The temperature of solution 1) was raised to 80 ° C and stirred for 6 hours.

3) The solution of No. 2 was filtered.

4) It was washed repeatedly with distilled water until no remaining acid was left on acid-treated activated carbon.

5) The washed activated carbon was dried at 120 ℃ for 6 hours to produce acid treated activated carbon.

&Lt; Preparation of palladium / carbon catalyst >

1) A 5 wt% hydrochloric acid aqueous solution was prepared. At this time, the amount of hydrochloric acid was at least 2 equivalents based on the palladium precursor.

2) 10% by weight (based on dry standard activated carbon) of a palladium precursor (PdCl ₂ 5.55 g) was added to the solution of the above 1), and the solution was completely dissolved by heating to 60 ° C. When the dissolution was completed, the temperature of the solution was lowered to room temperature. At this time, the mass of the aqueous solution was 60.5 g.

3) 44 g of a 10% by weight aqueous sodium hydroxide solution was poured into the solution of the above 2), and stirred for 15 minutes.

4) The active carbon carrier and distilled water were mixed and injected in the above 3) solution at a weight ratio of 1: 5.

5) The solution of No. 4 was heated to 72.5 캜 and stirred for 30 minutes.

6) The solution of No. 5 was filtered and washed to obtain a palladium / carbon catalyst.

[Comparative Example]

A commercial catalyst (10% Pd / C) used in the hydrogenation reaction was purchased to compare the activity and durability with the catalyst of the example. As the commercial catalyst, E101 NE / W of Evonik Co. was used.

[Evaluation example] The oxygen functional group according to the pretreatment of activated carbon

The Boehm titration method was used to identify acidic functional groups on the surface of activated carbon. 1 g of the activated carbon sample before and after the pretreatment was added to 50 ml of 0.05 M sodium hydroxide, sodium carbonate, sodium bicarbonate and hydrochloric acid, respectively, and the mixture was stirred for 24 hours. After filtering the activated carbon, 5 ml of the solution was titrated with 0.05 M hydrochloric acid solution and sodium hydroxide solution. Each functional group was calculated assuming that sodium hydroxide neutralizes carboxy group, phenol group, lactone group, sodium carbonate neutralizes carboxy group and lactone group, and sodium bicarbonate neutralizes lactone group. The basic functional groups on the surface of activated carbon were calculated from the amount neutralized by hydrochloric acid.

Functional group (mEq / g) Carboxy group Rock tone Phenol group Acid functional group Basic functional group Activated carbon before pretreatment 0.22 0.26 0.23 0.71 0.17 Activated carbon after pretreatment 0.74 0.61 0.52 1.87 0.13

As can be seen from the above results, the acidic functional groups such as carboxy group, lactone group, and phenolic group were greatly increased and the basic functional groups were relatively decreased in the activated carbon after the pretreatment. It can be expected that the interaction between pretreated activated carbon and palladium particles increases.

 [Evaluation example] Activity Evaluation of Palladium / Carbon Catalysts by Number of Catalyst Reuse Times

The reactivity of the catalysts of Examples and Comparative Examples was evaluated in the following order.

1) 0.2 g of a palladium / carbon catalyst was dispersed in a mixed solution of 4 g of benzyl ether and 89 g of tetrahydrofuran.

2) The 1) solution was charged into a hydrogenation reactor and then hydrogen gas was charged to 6 bar.

3) The hydrogenation reaction was started by operating the stirrer at 1000 rpm.

4) O-debenzylation reaction was carried out in the hydrogenation reactor for 10 minutes and the consumed hydrogen consumption was recorded in real time.

After the reaction, the catalyst was recovered by using a centrifuge, washed three times with tetrahydrofuran solution and reused for the hydrogenation reaction.

The results of the activity evaluation of the palladium / carbon catalyst according to the number of times of use of the catalyst are shown in FIG.

As a result of the experiment, it was confirmed that the reaction activity decreased as the number of reactions increased. It was confirmed that the reduction of reaction activity was less in the case of the catalyst of the present invention than that of the catalyst of the comparative example. Thus, it can be seen that the catalyst of the example has superior activity and durability as compared with the catalyst of the comparative example (commercial catalyst).

On the other hand, to confirm the durability of the palladium / carbon catalyst according to the number of times of use of the catalyst for the catalysts of Examples and Comparative Examples, the catalyst was recovered and the palladium content was measured by thermal analysis. The results are shown in Table 2.

Example Comparative Example Number of reactions 1 time Episode 2 3rd time 1 time Episode 2 3rd time Palladium content (wt%) 9.85 8.26 6.92 4.23 2.15 1.08

As a result of the experiment, it was confirmed that the palladium content of the catalyst of the present invention was not greatly decreased after the reaction according to the number of reactions, but that of the catalyst of the comparative example (commercial catalyst) was greatly decreased as the number of reactions increased. Specifically, the palladium content was only 1.5% in one reaction, 17.4% in two reactions, and 30.08% in three reactions.

As described above, it was confirmed that the palladium supported on carbon in the case of the catalyst of the Example was little lost during the reaction,

It is apparent that the specific description of the present invention described above is susceptible to various implementations by those skilled in the art.

It will be appreciated that those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

While the present invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (4)

A first step of preparing a carbon carrier pretreated with an acid,
A second step of dissolving the palladium precursor in an acid solution to prepare a palladium precursor solution,
A third step of adding an oxidizing agent aqueous solution to the palladium precursor solution in the second step and stirring to produce palladium particles,
A fourth step of injecting the carbon carrier prepared in the first step into the aqueous solution of the palladium precursor into which the aqueous solution of the oxidizing agent is introduced,
A fifth step of supporting the palladium particles on the inserted carbon carrier
&Lt; / RTI &gt; The method according to claim 1,
In the first step,
A step of injecting a carbon carrier into an acid solution,
Stirring the acid solution into which the carbon carrier has been introduced at 30 DEG C to 100 DEG C for 30 minutes to 24 hours,
Filtering and washing the stirred acid solution
/ RTI &gt; wherein the catalyst is a palladium / carbon catalyst. The method according to claim 1,
In the third step,
Wherein the oxidizing agent aqueous solution to be added to the palladium precursor solution in the second step is charged at a predetermined amount. A palladium / carbon catalyst prepared by the method of any one of claims 1 to 3 and having a reduction ratio of palladium particles within 1.5% after a single reaction.

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