A catalyst for selective hydrogenation of unsaturated compounds and method for selective hydrogenation of unsaturated compounds

 

(57) Abstract:

The object of the invention is a catalyst for selective hydrogenation of unsaturated compounds based on noble metal and/or oxide of the noble metal on alumina, in which the initial state has the following characteristics directii x-rays:

This catalyst was prepared due to the fact that the noble metal in the form of an aqueous solution of its salt is introduced into the alumina. 2 S. p. and 5 C.p. f-crystals, 3 tab., 2 Il.

The invention relates to the field of selective hydrogenation of unsaturated compounds, in particular to a catalyst and method of selective hydrogenation of unsaturated compounds and to a method for producing the catalyst.

A known catalyst for selective hydrogenation of unsaturated compounds, for example, based on the noble metals supported on a carrier, such as alumina (DE 27 58 318 C2, class C 07 C 15/085, 24.05.89).

To achieve higher initial selectivity to the implementation of the selective hydrogenation catalyst is subjected to many hours of pre-treatment gidriruemyi compounds in the absence of hydrogen at elevated temperature.

The objective of the invention is to develop a catalyst having high initial selectivity and thus providing an immediate effective use in the processes of selective hydrogenation of unsaturated compounds.

This object is achieved by a catalyst based on a noble metal and/or oxide of the noble metal on alumina as a carrier due to the fact that he is in the initial state has the characteristic x-ray diffraction (see table. 2).

Thus d is the interplanar distance, and J/J0indicates the relative intensity of reflection of x-rays.

The catalyst preferably contains palladium and/or palladium oxide.

In addition to palladium and/or palladium oxide catalyst may also contain noble metals and/or oxides of noble metals selected from the group of platinum, iridium, ruthenium and rhodium.

For catalyst fundamentally fit all noble metals commonly used in the hydrogenation catalysts.

The catalyst content of noble metals and/or oxides of noble metals is 0.01 - 3% by weight of the catalyst, especially predpochtite is preferably in the outer marginal zone of the catalyst, having a thickness of 5 to 200 μm, particularly preferably 30 to 100 μm.

For catalyst as a carrier suitable different phases of aluminum oxide. Preferably used is alumina and/or alumina as a carrier.

Contained in the fresh catalyst (=catalyst in the initial state, i.e. before the implementation of the selective hydrogenation) primary crystallites preferably have a size of 0.1 to 30 nm, particularly preferably 1 to 15 nm.

The sodium content of the fresh catalyst may be about 0.001 - 3 wt. %, preferably 0.01 to 1 wt.%.

In addition, fresh catalyst may contain other compounds of alkali and/or alkaline earth metals, nitrates, carbonates, phosphates, sulfates, oxides of silicon and iron oxide in an amount of 1 wt.%.

The total BET surface fresh catalyst may be 50 - 250 m2/g of fresh catalyst, in particular 100 - 180 m2/2 fresh catalyst.

Pore volume of fresh catalyst may be 0.2 - 0.8 ml/g of fresh catalyst, preferably 0.3 to 0.6 ml/g of fresh catalyst, and the size of pores of the fresh catalyst can be mainly 3 to 30 nm, preferably 4 to 20 nm.

Selective hydrogenation of unsaturated compounds on the catalyst preferably performed at a pressure of 2 to 30 bar abs. and at 40 - 18oC. it is Recommended that the molar ratio of hydrogen to unsaturated compounds is 1:1 to 3:1.

Selective hydrogenation, in particular, are methylsterol.

A further object of the invention is a method of producing catalyst, namely, that of the noble metal in the form of an aqueous solution of its salt is introduced into the alumina.

Upon receipt of the catalyst can come from precursors of alumina, for example, bayerite and/or pseudo-boehmite. They can be treated with acid, preferably nitric acid, followed by molding. Thus obtained molded product can be dried at a temperature of 80 - 140oC and calcinate at 400 - 700oC.

Thus obtained alumina can be impregnated with a water solution of salt of the noble metal. Impregnation can be performed at a temperature of aluminum oxide from room temperature to 100oC. the Impregnated carrier is dried preferably at 50 - 200oC followed by heat treatment at 250 - 650oC.

Get € as an example of selective hydrogenation describes the response-methylstyrene to cumene. At the same time as an unintended by-product can be obtained hydrogenated in the nucleus of isopropylcyclohexane, the formation of which adversely affect the reaction, and thus the output of the cumene.

Example 1. The catalyst was prepared as follows. As a precursor serving as a carrier of aluminum oxide used bayerite, in which the stirrer is treated with nitric acid, followed by molding. Then the molded product is dried at 120oC and calicivirus at 650oC.

Thus obtained alumina is impregnated with an aqueous solution of palladium nitrate (II), and the temperature of the medium is approximately 25oC. the Impregnated carrier is dried at 110oC and then calicivirus at 450oC. the thus Obtained catalyst 1 contains 0.5% of palladium and palladium oxide, calculated as palladium.

In Fig. 1 shows x-ray diffraction chart (a) of catalyst 1, showing the relative intensity depending on the diffraction angle, indicated as 2 [deg].

20 g of catalyst 1 is fed to the apparatus, consisting of a reactor, heat exchanger, separator and pump.

This equipment fill 1 000 temperature 76oC. Then the raw material is subjected to hydrogenation at a hydrogen pressure of 8 bar abs. The chemical composition of the hydrogenation product is also listed in the table. 3.

After a three-hour hydrogenation of the residual content-methylstyrene in the product of hydrogenation is less than 10 weight. h/mill. The content of isopropylcyclohexane raised only 90 weight.h./mill.

Example 2. Catalyst 2 was prepared as follows:

As a precursor serving as a carrier of aluminum oxide using pseudo-boehmite, in which the mixer is treated with nitric acid, followed by molding. The molded product is dried at 120oC and calicivirus at 550oC.

Thus obtained alumina is impregnated with an aqueous solution of palladium nitrate (II), and the temperature of the media is 95 - 100oC. the Impregnated carrier is dried at 130oC and then calicivirus at 450oC. the thus Obtained catalyst 2 contains 1% palladium and palladium oxide, calculated as palladium.

In Fig. 2 shows x-ray diffraction chart (a) of catalyst 2, showing the relative intensity depending on the diffraction angle, indicated as 2 [deg].

the composition of the hydrogenation product is also listed in the table. 4.

After two hours the reaction content-methylstyrene in the hydrogenation product is just another 0,029 wt.%. The content of isopropylcyclohexane increased only at 110 weight.h./mill.

Example 3. Selective hydrogenation is conducted analogously to example 1, but with the difference that the reaction temperature is 130oC. as catalyst for the hydrogenation using the catalyst of example 1. On the basis of 18 wt.% -methylstyrene in raw materials after two hours of reaction, its residual content in the product of hydrogenation is less than 10 weight.h./mill. The content of isopropylcyclohexane increased only 160 weight.h./mill.

1. A catalyst for selective hydrogenation of unsaturated compounds based on noble metal and/or oxide of the noble metal on alumina as the carrier, and the total content of noble metal and/or oxide of the noble metal is 0.01 to 3% by weight of a catalyst, characterized in that in the initial state, the catalyst has the following x-ray diffraction:

d (10-10m) (I/I0< / BR>
4,51 5 10

was 2.76 15 40

2,64 15 40

2,37 40 45

2,27 25 35

2.15 To 15

1,97 55 70

1,66 15

1.52m 15 30

1,39 100

1,31 15

the outer marginal zone of the catalyst, having a thickness of 5 to 200 μm.

3. The catalyst PP.1 and 2, characterized in that in the initial state, it has a primary crystallite size of 0.1 to 30 nm.

4. The catalyst PP. 1 to 3, characterized in that in the initial state has a sodium content of 0.001 to 3 wt.

5. The method of selective hydrogenation of unsaturated compounds when heated in the catalyst based on a noble metal, wherein the used catalyst PP.1 4.

6. The method according to p. 5, wherein the process is carried out at a pressure of 2

30 bar abs. and a temperature of 40 to 180oC.

7. The method according to PP.5 and 6, characterized in that the process is carried out at a molar ratio of hydrogen to unsaturated aromatic compounds, is equal to 1 1 to 3 1.

 

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