RU2258561C1 - Palladium-containing hydrogenation catalyst preparation method - Google Patents

Abstract

FIELD: hydrogenation-dehydrogenation catalysts.

SUBSTANCE: palladium-containing hydrogenation catalyst, which can be used to control rate of autocatalytic hydrogenation reactions, is prepared by hydrogen-mediated reduction of bivalent palladium from starting compound into zero-valence palladium and precipitation of reduced zero-valence palladium on carbon material, wherein said starting material is tetraaqua-palladium(II) perchlorate and said carbon material is nano-cluster carbon black. Reduction of palladium from starting compound and precipitation of zero-valence palladium on carbon material are accomplished by separate portions.

EFFECT: increased catalytic activity, enabled catalyst preparation under milder conditions, and reduced preparation cost.

1 dwg, 1 tbl, 12 ex

Description

The invention relates to the field of physical chemistry and can be used to control the rate of autocatalytic hydrogenation reactions.

Hydrogenation reactions are among the main industrial processes that are implemented, as a rule, in the presence of a catalyst, in particular, for the synthesis of alicyclic and cyclic saturated organic compounds, high-quality gasoline, etc.

According to published data (Grove D.E. Plat. Met., 2002, 46, (2) 92), about 75% of industrial hydrogenation processes are carried out on a Pd / C catalyst containing 5% palladium metal. The rich catalytic chemistry of palladium covers practically the entire spectrum of reactions necessary for organic synthesis. The method for producing the Pd / C catalyst is based on the reduction of divalent palladium from the starting compound and the subsequent deposition of reduced palladium on a variety of activated carbons.

A known method for producing a palladium-containing hydrogenation catalyst by reducing divalent palladium from the starting compound and depositing the reduced palladium on carbon material, where the starting compounds are Pd (II), Tsuji J. Palladium reagents and catalysts-innovations in organic syntheses complexes. John Wiley & sons, Chichester. 1995.595 p.; Grove D.E. Plat. Met., 2002, 46, (1) 48.

There is also known a method for producing a palladium-containing hydrogenation catalyst by reducing divalent palladium to nullivalent palladium and depositing reduced nullivalent palladium on carbon material, using palladium (II) chloride as the starting compound, see HMColquhoun, Y. Holton, et all, "New Pathways for Organic Synthesis "(" New Ways of Organic Synthesis "), translation from English, M. S. Ermolenko and V. G. Kiseleva, M.," Chemistry ", 1989, p. 361, 2 paragraph above.

A solution of palladium chloride (8.2 g) in hydrochloric acid (20 ml of concentrated acid in 50 ml of water) is heated for 2 hours, added with stirring to a hot (80 ° C) suspension of coal in water (93 g in 1.2 l water), previously washed with nitric acid.

You can use almost any coal with a sufficiently large specific surface treated with nitric acid (10%) for 2-3 hours, followed by washing with water to remove the acid and dried at 100 ° C. Then formaldehyde (8 ml of a 37% solution) and sodium hydroxide solution are successively added to a strongly alkaline reaction. After 10 minutes, the resulting catalyst was filtered off, washed with water (10 × 250 ml) and dried in vacuum over calcium chloride. The yield of palladium is 5% on coal 93-98%.

This method is adopted as a prototype of the present invention.

Its disadvantage is the low activity of the catalyst obtained according to this method, the need to create an elevated temperature (above 60 ° C) and pressure (above 5 atm) for the catalysis process. This is due to the complexity of the activation of the reaction centers of the catalyst obtained by the prototype method. In addition, this method requires the presence of at least 5% reduced nullvalent palladium, which leads to a high cost of the process.

The present invention is based on the task of creating a method for producing a palladium-containing hydrogenation catalyst, which would have high catalytic activity, could be carried out under milder conditions (at room temperature and normal (atmospheric) pressure), as well as reducing the cost of implementing the method.

According to the invention, this problem is solved due to the fact that in the method for producing a palladium-containing hydrogenation catalyst by hydrogen reduction of divalent palladium from the starting compound to zero-valent palladium and deposition of the reduced nullivalent palladium on carbon material, tetra-aquapalladium (II) perchlorate is used as the starting compound, as carbon the material uses nanocluster soot, and the reduction of palladium from the starting compound and the deposition of reduced zero valence palladium on the carbon material is carried out in separate portions.

The applicant has not identified sources containing information about technical solutions identical to the present invention, which allows us to conclude that it meets the criterion of "novelty."

The implementation of the distinguishing features of the invention leads to an important technical result: as a result of using nanocluster soot (not containing fullerenes) as a carbon material, the catalytic activity of reduced palladium increases significantly, its content can be reduced by 5–2 times with equal activity, and thanks to it deposition on a carbon carrier in separate portions reduces the content of reduced palladium to fractions of a percent. Thus, the whole process is significantly cheaper.

The applicant has not found any sources of information containing information about the impact of the claimed distinctive features on the technical result achieved as a result of their implementation. This, according to the applicant, indicates that this technical solution meets the criterion of "inventive step".

The drawing shows a diagram of a plant for implementing the inventive method for producing a palladium-containing hydrogenation catalyst.

Installation for implementing the method includes a reactor 1 with a mixing device 2. Hydrogen is in the cylinder 3. The reactor 1 is connected to a pressure gauge 4.

The method is implemented as follows.

In Example 1, a catalyst was obtained with a reduced nullivalent palladium content of 0.1% Pd upon its single deposition on a carbon support.

In examples 2 and 3, a catalyst containing 0.2% Pd in a single and batch deposition, respectively.

In examples 4 and 5 - 0.3% Pd, in examples 6 and 7 - 0.4% Pd, 8 and 9 - 0.5% Pd, 10 and 11 - 1.0% Pd for single and batch deposition, respectively .

In Example 12, a catalyst was prepared with a content of 5.0% Pd in a single deposition.

To obtain the catalyst in the first example, 1.41 L of distilled water was placed in reactor 1, 4.21 mg of carbon nanocluster carbon black was added, 0.66 ml of 6.0 · 10 ^-2 mol / L tetra-aquapalladium (II) perchlorate solution [Pd ( H ₂ O) ₄ ] (ClO ₄ ) ₂ containing 0.7 mol / L perchloric acid and stirred for 0.5 hours. Then, hydrogen was passed through the prepared solution for 2 hours. Stirring is stopped, the reaction mixture is left to stand for 2-4 hours. The precipitate formed is filtered off on a Schott filter, washed repeatedly with distilled water and dried in a vacuum desiccator over P ₂ O ₅ or potassium hydroxide for 2 days. The yield of catalyst 1 is 98-99%.

In examples 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 are added in an amount, respectively: 1.32; 1.98; 2.64; 3.30; 6.60; 33.0 ml of a solution of [Pd (H ₂ O) ₄ ] (ClO ₄ ) ₂ with a concentration of 6.0 · 10 ^-2 mol / L.

Moreover, in examples 3, 5, 7, 9, 11, the deposition of reduced palladium on nanocluster soot was carried out in batches: in example 3 - 2 servings, in example 5 - 3 servings, in example 7 - 4 servings, in example 9 - 5 servings, in example 11 - 10 servings.

After the first portion was precipitated, aging was carried out for 30 minutes, and then hydrogen was passed for 2 hours with stirring, and then the next portion was introduced.

The influence of the method of applying palladium on carbon nanocluster soot and the catalytic activity of the obtained products were studied in each example using the following reactions:

reaction 1: C ₂ H ₄ + H ₂ → C ₂ H ₆ ;

reaction 2: 2Fe _aq ⁺³ + H ₂ → 2Fe _aq ⁺² + 2H ⁺ ;

reaction 3: sunflower oil + H ₂ → hydrogenated products.

Each catalyst in an amount of 100 mg was placed in a reactor and 10 ml of distilled water was added in the case of reaction (1); reaction (2) - 10 ml of an aqueous solution of 0.01 mol / l of iron (III) sulfate containing 0.02 mol / l of sulfuric acid; reactions (3) - 6 ml of Sloboda vegetable oil. The reactor was evacuated and filled with hydrogen (reactions (2, 3) or an ethylene-hydrogen mixture with a volume ratio of 1: 1 (reaction (1).

Reactions were carried out at a temperature of 18-25 ° C and normal atmospheric pressure. Reaction rates were recorded by the change in the volume of absorbed gases over time. The data obtained are shown in table 1.

Table 1
The specific hydrogenation rate (the amount of H ₂ absorbed in moles / 1 mol Pd hour) in reactions (1-3) in the presence of catalysts (1-12), at a temperature of 25 ° C, a hydrogen pressure of 1 atm) Example No. The concentration of Pd in the sample,% Reaction 1 Reaction 2 Reaction 3 Specific hydrogenation rate single deposition of Pd batch deposition of Pd single deposition of Pd batch deposition of Pd single deposition of Pd batch deposition of Pd 1 0.1 155 155 80 80 35 35 2,3 0.2 215 320 158 220 49 100 4,5 0.3 295 580 230 425 59 114 6.7 0.4 205 530 210 380 53 102 8.9 0.5 130 390 96 260 45 82 10.11 1,0 90 205 90 220 twenty 68 12 5,0 53 - 99 - 3.3 -

Claims (1)

A method of producing a palladium-containing hydrogenation catalyst by hydrogen reduction of divalent palladium from the parent compound to nullivalent palladium and deposition of the reduced nullivalent palladium onto carbon material, characterized in that tetraquapalladium (II) perchlorate is used as the starting compound, nanocluster soot is used as the carbon material, and reduction palladium from the parent compound and the deposition of reduced nullivalent palladium on a carbon mat IAL performed in batches.