RU2326731C1 - Method for producing palladium containing catalyst of hydrogenation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in controlling the rate of the autocatalytic reactions of hydrogenation. The method of producing the palladium containing hydrogenation catalyst is described, including the reduction of bivalent palladium from the initial compound and precipitation of the reduced palladium at the carbon nanomaterial, and, as the initial compound, the (1-5)×10^-5 mol/L water solution of tetraaqua palladium (II) perchlorate is used, and 0.1-0.5 mass percent of the reduced palladium is plated on the carbon nanomaterial.

EFFECT: increased catalytic activity is provided.

5 tbl, 1 dwg

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 the literature, see Grove D.E. Plat. Met., 2002, 46, (2), 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. Thus, Pd / C is currently the most successful system for the implementation of catalytic organic synthesis processes.

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, John Wiley & sons, Chichester complexes 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 from the starting compound and depositing the reduced palladium on carbon material, using palladium (II) chloride as the starting compound, see N. M. Colhhoun, Y. Holton, et all. "New Pathways for Organic Synthesis" (translated from English, M.S. Ermolenko and V.G. Kiseleva, M .: Chemistry, 1989, p. 361.

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 and 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 area, 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 vacuo over calcium chloride. The yield of palladium 5% on coal 93-98%.

The disadvantage of this technical solution is the low activity of the catalyst obtained according to this method, the need to create elevated (over 60 ° C) temperatures and pressures (over 5 atm) for the catalysis process. This is due to the complexity of activation of the reaction centers of the catalyst obtained according to this method.

A known method of producing a palladium-containing hydrogenation catalyst by reducing divalent palladium from the starting compound and depositing the reduced palladium on carbon material, characterized in that tetra-aquapalladium (II) perchlorate is used as the starting compound, and the reduced palladium is deposited on carbon nanomaterial, RU 2240182. This technical solution adopted as a prototype of the present invention.

It should be noted that the catalysts obtained according to the prototype method have a significantly higher catalytic activity in the hydrogenation of, in particular, alkenes compared to catalysts obtained by applying palladium on activated carbon. However, palladium deposited on carbon nanomaterial in accordance with the prototype method forms nanoclusters with relatively low catalytic activity.

The objective of the present invention is to provide a method for producing a palladium-containing hydrogenation catalyst, which provides an increase in its catalytic activity.

According to the invention, this problem is solved due to the fact that in the method for producing a palladium-containing hydrogenation catalyst by reducing divalent palladium from the starting compound and depositing the reduced palladium on carbon nanomaterial, an aqueous solution of tetra-aquapalladium (II) perchlorate is used as the starting compound, an aqueous solution of tetra-aquapalladium ( II) perchlorate at a concentration (1-5) × 10 ^-5 mol / l of the substance, and the reduced palladium is precipitated on the carbon nanomaterial in The number of 0.1-0.5 wt.% of the total weight of the catalyst.

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."

Due to the implementation of the distinguishing features of the invention, palladium nanoclusters of significantly smaller sizes are formed than according to the prototype method. When the concentration of perchlorate tetra-aquapalladium (II) in an aqueous solution is less than 1 × 10 ^-5 mol / L, the sorption of palladium nanoclusters on nanocarbon material sharply decreases, while a significant part of the palladium nanoclusters remains in solution. At a concentration of tetra-aquapalladium (II) perchlorate above 5 × 10 ^-5 mol / L, aggregation of palladium nanoclusters occurs, which leads to a decrease in the catalytic activity of the product.

When the reduced palladium is deposited on carbon nanomaterial in an amount of less than 0.1 wt.% And more than 0.5 wt.% Of the total catalyst mass, a sharp decrease in catalytic activity occurs.

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 the installation diagram for implementing the inventive method. 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 gauge installation.

The method is implemented as follows.

An aqueous solution of tetraacvapalladium (II) perchlorate containing 0.7 ml of perchloric acid is placed in reactor 1, in the first example with a concentration of Pd ⁺² aq 1 × 10 ^-5 mol / L, in the second - 1.87 × 10 ^-5 mol / l, in the third - 2.83 × 10 ^-5 mol / l, in the fourth - 5 × 10 ^-5 mol / l and in the fifth - 7.35 × 10 ^-5 mol / l. Then carbon nanomaterial is introduced, which can be used fullerene C ₆₀ , or a cathode deposit, or carbon nanotubes, or carbon black. Stirring is carried out for 0.5 hours. The recovery of divalent palladium is carried out by passing through a solution of hydrogen for 2 hours. In each example, reduced palladium was deposited on the carbon material in the following amounts, based on the total weight of the catalyst: 0.05; 0.1; 0.2; 0.3; 0.4; 0.5; 1,0.

The specific activity (mol H ₂ / mol Pd × sec) of the obtained catalysts was determined by the example of the hydrogenation of the Sloboda refined sunflower oil.

50 ml of oil was charged into a 250 ml reaction flask. 25 mg of the corresponding catalyst was introduced into the reactor, then the mixture was thermostated at a temperature of 180 ° C, the reactor was evacuated and filled with hydrogen at a pressure of 1 atm; the reactor was evacuated and filled with hydrogen three times. The process was carried out with constant stirring for 1.5 hours. The speed of the process was controlled by a gasometric method by the amount of absorbed hydrogen. The results are shown in tables 1-5.

Table 1 The concentration of tetraaquapalladium (II) perchlorate in an aqueous solution (mol / l) 1.0 × 10 ^-5 The concentration of palladium deposited on carbon nanomaterial, (% of the total catalyst mass) 0.05 0.1 0.2 0.3 0.4 0.5 1,0 The specific activity of the catalyst, (mol H ₂ / mol Pd × sec) 3.2 13.1 13.6 14.0 13.1 10.0 4.0 table 2 The concentration of tetraaquapalladium (II) perchlorate in an aqueous solution (mol / l) 1.87 × 10 ^-5 The concentration of palladium deposited on carbon nanomaterial, (% of the total catalyst mass) 0.05 0.1 0.2 0.3 0.4 0.5 1,0 The specific activity of the catalyst, (mol H ₂ / mol Pd × sec) 2,5 15.8 15.7 14.0 13.5 13.1 5.1

Table 3 The concentration of tetraaquapalladium (II) perchlorate in an aqueous solution (mol / l) 2.83 × 10 ^-5 The concentration of palladium deposited on carbon nanomaterial, (% of the total catalyst mass) 0.05 0.1 0.2 0.3 0.4 0.5 1,0 The specific activity of the catalyst, (mol H ₂ / mol Pd × sec) 4.8 13.1 14.2 15.1 13.6 13.0 6.3 Table 4 The concentration of tetraaquapalladium (II) perchlorate in an aqueous solution (mol / l) 5.0 × 10 ^-5 The concentration of palladium deposited on carbon nanomaterial, (% of the total catalyst mass) 0.05 0.1 0.2 0.3 0.4 0.5 1,0 The specific activity of the catalyst, (mol H ₂ / mol Pd × sec) 3.4 14.2 16.1 13.0 13.0 12,2 3.0

Table 5 The concentration of tetraaquapalladium (II) perchlorate in an aqueous solution (mol / l) 7.35 × 10 ^-5 The concentration of palladium deposited on carbon nanomaterial, (% of the total catalyst mass) 0.05 0.1 0.2 0.3 0.4 0.5 1,0 The specific activity of the catalyst, (mol H ₂ / mol Pd × sec) 1.4 3.0 4.1 4.4 5.1 4.2 0.9

Claims (1)

A method of producing a palladium-containing hydrogenation catalyst by reducing divalent palladium from the parent compound and precipitating the reduced palladium on carbon nanomaterial, wherein an aqueous solution of tetraacvapalladium (II) perchlorate is used as the starting compound, characterized in that an aqueous solution of tetraacquapalladium (II) perchlorate with a concentration of (1) is used 5) · 10 ^-5 mol / l of the substance, and the reduced palladium is precipitated on the carbon nanomaterial in an amount of 0.1-0.5 wt.% of the total weight kata izatora.