CN100402145C - Catalyst for benzene selective hydrogenation reaction, preparation method and application - Google Patents

Abstract

The invention provides a ruthenium catalyst for selective hydrogenation of benzene and a preparation method thereof, which are characterized in that: (1) the nucleation and growth of ruthenium nanoparticles are controlled in a nanoreactor composed of water nuclei surrounded by surfactants (2) The porous inorganic protective layer is formed by in-situ hydrolysis of orthosilicate in a nanoreactor system containing ruthenium nanoparticles. The ruthenium content of the catalyst is 7-15% by mass, and it is applied to the selective hydrogenation reaction of benzene. When the conversion rate of benzene is 40%, the selectivity of cyclohexene is 72-75%, and the TOF(H ₂ ) reaches more than 3560h ^-1 ; The rate can reach more than 40%.

Description

Catalyst for benzene selective hydrogenation reaction, preparation method and application

technical field

The invention relates to a catalyst for selective hydrogenation of benzene.

The present invention also relates to a method for preparing the above-mentioned catalyst.

The present invention also relates to the application of the catalyst in the selective hydrogenation of benzene to prepare cyclohexene.

Background technique

Cyclohexene is an important organic chemical raw material, which can be used in synthetic resins, plastics, fibers, rubber, detergents, dyes, pesticides, explosives and medicines; such as L-lysine, cyclohexene oxide, etc. value product. Traditional methods such as cyclohexanol dehydration, halocyclohexane dehalogenation, Birch reduction, etc. have high costs; the development of a new process for the preparation of cyclohexene by selective hydrogenation of cheap benzene as raw material reduces the production cost of cyclohexene , broaden its scope of application, so that it can be used in the preparation of cyclohexanol, caprolactam, adipic acid and other products with high demand, has high economic benefits, and has received widespread attention.

The catalysts used in the selective hydrogenation of benzene are mainly prepared by co-precipitation and impregnation. Asahi Kasei [US 4,734,536] has reported a typical ruthenium black catalyst, which is obtained by precipitating ruthenium trichloride with sodium hydroxide; the conversion rate of benzene can reach 60%, and the selectivity is 79.6%; but the precious metal ruthenium content of the catalyst Very high and expensive, TOF(H ₂ ) is only 292h ^-1 .

The patent [US 5,569,803] reported a highly active catalyst prepared by an impregnation method. The catalyst uses 5wt% _ZrO2 modified silica support, the conversion rate of benzene on this catalyst is 58.5%, and the selectivity is 69.2%. TOF(H ₂ ) is 4103h ^-1 .

Compared with the precipitation method, the catalyst prepared by the impregnation method usually has smaller metal particles and higher specific activity at low loads; the development of a catalyst with a high load and smaller particle size can not only improve the total catalyst Activity, and can improve device efficiency and reduce equipment investment. Therefore, it has important application background and scientific significance to prepare a stable, fine, high-loaded ruthenium catalyst with small particle size.

Under the action of surfactants and co-surfactants, water (or aqueous solution) can be dispersed in the continuous oil phase as very small droplets (8-80nm), forming a thermodynamically stable and transparent (or translucent) Water-in-oil (W/O) dispersion system. When the system is used to prepare nanoparticles, the reactants are surrounded by an interfacial film composed of surfactants and separated from each other to form a nanoreactor. Because the nucleation and growth processes of nanoparticles are uniformly carried out under the protection of the nanoreactor, the distribution of the obtained nanoparticles is relatively narrow. In addition, the size and morphology of nanoparticles can be changed through the regulation of reactor composition (surfactant, water, oil phase, co-surfactant) and kinetics [Zarur A J, Ying JY. Reverse microemulsion synthesis of nanostructured complex oxides forcatalytic combustion, nature, 2000, 403(6): 65-67] [Person K, Thevenin P O, Jansson K, et al.Preparation of aluminum-supported palladium catalysts for complete oxidation of methane, Appl.Catal.A: Gereral, 2003 , 249(1):165-174][Ojeda M, Rojas S, Boutonnet M, et al.Synthesis of Rhnano-particles by the microemulsion technology: Particle size effect on the CO+H ₂ reaction, Appl.Catal.A:General , 2004, 274(1/2): 33-41].

Contents of the invention

The object of the present invention is to provide a catalyst for selective hydrogenation of benzene.

Another object of the present invention is to provide a method for preparing the above catalyst.

In order to achieve the above object, the catalyst provided by the present invention has the expression Ru-MB/SiO ₂ ,

Wherein M is an auxiliary agent, which is one or more of elements of groups IIB, VIB, VIII such as Cr, Mn, Fe, Co, Ni, Cu, Zn, W, Ag, Au, preferably Zn and Fe;

The loading of ruthenium (Ru) is 2-20% of the total weight of the catalyst;

The loading of the auxiliary agent is 0-20% of the total weight of the catalyst;

The loading of B is 0-5% of the total weight of the catalyst.

The preparation method provided by the invention is:

1) Prepare a ruthenium-containing aqueous solution with a mass ratio of Ru:M:H ₂ O=1:0-2:4-20;

2) According to the mass ratio, the aqueous solution in step 1: oil: surfactant: co-surfactant = 1: 10-50: 5-50: 0-20 is mixed, and stirred at room temperature to obtain solution A;

3) Prepare solution B with surfactant, oil and reducing agent solution, wherein the reducing agent is potassium borohydride, formaldehyde or hydrazine hydrate; the mass ratio of the three in the solution is 10-50% oil, 5-50% Surfactant, 5-20% potassium borohydride solution (or formaldehyde or hydrazine hydrate aqueous solution, 2-10% by mass);

4) Mix solutions A and B under stirring at 3-40°C, add ethyl orthosilicate, the amount added is 4-49 times that of ruthenium in terms of silicon dioxide, add alkali (such as ammonia water) for precipitation, separate and collect the precipitate The catalyst is obtained.

In the preparation method of the present invention, the ruthenium precursor is ruthenium trichloride, ruthenium acetylacetonate or ruthenium nitrate, preferably ruthenium trichloride.

In the preparation method of the present invention, M is an auxiliary agent, which is one or more of Cr, Mn, Fe, Co, Ni, Cu, Zn, W, Ag or Au, preferably Zn and Fe.

In the preparation method of the present invention, the oil is cyclohexane, pentane, hexane, n-octane, benzene, toluene, xylene, heptane, hexanol, pentanol, butanol or octanol.

In the preparation method of the present invention, the surfactant can be anionic or cationic surfactants, such as sodium dodecylsulfonate, two (2-ethylhexyl) sodium succinate (AOT), cetyl trimethyl Ammonium bromide (CTAB), etc., can also be non-ionic surfactants, such as nonylphenol polyoxyethylene ether (NP), sorbitan fatty acid ester polyoxyethylene ether (TWEEN) or pentadecyl polyoxyethylene ether Oxyethylene ether (PEGDE), etc., preferably nonylphenol polyoxyethylene ether (NP).

In the present invention, in-situ hydrolysis of orthosilicate ethyl in the microreactor system containing ruthenium nanoparticles forms a porous inorganic protective layer, disperses and stabilizes ruthenium metal nanoparticles,

In the present invention, the nucleation and growth of ruthenium nanoparticles are controlled in a nanoreactor composed of water nuclei surrounded by surfactants. According to the needs of the target reaction, by changing the composition of the reactor (surfactant, Water, oil phase, co-surfactant) and kinetics and other simple means to regulate its particle size and distribution. Finally, the catalyst was prepared by dispersing and stabilizing the ruthenium metal nanoparticles by forming a porous inorganic protective layer.

The catalyst prepared by the invention can be applied to the selective hydrogenation reaction of benzene, and has high activity and selectivity.

According to the present invention, the selective hydrogenation reaction of the catalyst is carried out in a stainless steel autoclave with a volume of 500 mL. The pressure is 2-10MPa, the temperature is 100-180°C, and the stirring speed is 1000rpm.

Detailed ways

The reaction is further described by examples below, but the present invention is not limited by the following examples.

In the following examples and comparative examples, conversion and selectivity are defined by the following formulae.

The analytical instrument is an Agilent 4890D gas chromatograph.

Example 1

Preparation of solution A: 8.0g of surfactant nonylphenol polyoxyethylene ether-7 (NP-7), 0.86g of ruthenium trichloride containing 14.55% by mass ratio, 50mL of cyclohexane, in a 500mL four-hole circle Mix in a bottom flask at 30°C with stirring to obtain translucent solution A.

Preparation of solution B: Add 8.0 g of surfactant NP-7 and 2.14 g of 6.54% potassium borohydride aqueous solution in mass ratio to 30 mL of cyclohexane, control the temperature at 30° C., and stir to obtain translucent solution B.

Catalyst preparation: control the temperature at 30°C, under the protection of nitrogen, add solution B dropwise to solution A under stirring. After the dropwise addition, add 2.68g of tetraethyl orthosilicate and 10mL of ammonia water with a concentration of 12.5% by mass, overnight. After the reaction, add 50mL of acetone, centrifuge, and wash with absolute ethanol and water. The catalyst number obtained is is 1.

Catalyst activation: take the above catalyst, add 100mL of 0.6M zinc sulfate, and activate it for 10 hours under the condition of 5MPa, 145°C and 300rpm.

120 mL of 0.6 M zinc sulfate, all the catalysts mentioned above and 60 mL of benzene were added to a stainless steel autoclave with a volume of 500 mL and previously replaced with hydrogen. After raising the temperature to 140° C. with slight stirring, 6.0 MPa of hydrogen gas was introduced, and the stirring speed was 1000 rpm. The reaction results are shown in Table 1.

Comparative Example 1

Catalyst preparation by supported method: take 0.75g of commercial silica carrier, add 1.40g of ruthenium trichloride solution with a concentration of 8.93% by mass ratio under stirring, soak overnight, dry at 100°C for 12h, and hydroborate in 30mL with a concentration of 0.67% by mass ratio Potassium was reduced to obtain comparative catalyst 1. Catalyst activation and reaction conditions are the same as in Example 1, and the reaction results are shown in Table 1.

Example 2

Add 8.0g of surfactant NP-7 and 2.15g of hydrazine hydrate solution with a mass ratio of 14.80% to 30mL of cyclohexane, control the temperature at 30°C, and stir to obtain translucent solution B. The rest of the preparation steps are the same as in Example 1. Catalyst number 2 was obtained. The reaction results are shown in Table 1.

Example 3

Add 8.0g of surfactant NP-7 and 2.43g of 5.62% formaldehyde solution in mass ratio to 30mL of cyclohexane, control the temperature at 30°C, and stir to obtain translucent solution B. The rest of the preparation steps are the same as in Example 1, and the number of the obtained catalyst is 3. The reaction results are shown in Table 1.

Example 4

In addition to changing the preparation of A to: 8.0g surfactant NP-7, 0.80g mass percentage of 14.55% ruthenium trichloride aqueous solution, 50mL cyclohexane, mixed in a 500mL four-necked round bottom flask, 30 ° C and stirred A translucent solution was obtained, and 0.75 g of silicon dioxide solid was added to this solution to obtain solution A. Obtained Catalyst Preparation Other steps were carried out using the method in Example 1, and the obtained catalyst was numbered 4. The reaction results are shown in Table 1.

Example 5

Preparation of A nanoreactor: 8.0g surfactant NP-7, 0.86g aqueous solution containing 29.09% ruthenium trichloride by mass ratio and 1.04% zinc sulfate by mass ratio, 50mL cyclohexane, in a 500mL four-hole round bottom Mix in the flask, control the temperature to 30° C., and stir to obtain a translucent solution A composed of nanoreactors.

The preparation of B nanoreactor: 8.0g surfactant NP-7 and 2.23g concentration are mass ratio 10.32% potassium borohydride aqueous solution to add 30mL cyclohexane, control temperature is 30 ℃, stir, obtain the composition that is made up of nanoreactor Translucent solution B.

The other steps of catalyst preparation were carried out using the method of Example 1, and the obtained catalyst number was 5. The reaction results are shown in Table 1.

Example 6

Except that the surfactant of A was changed to 5.0 g of NP-7, other steps were carried out by the method of Example 5, and the obtained catalyst number was 6. The reaction results are shown in Table 1.

Example 7

Except that the surfactants of A and B were changed to NP-7 with a mass of 11.0 g, other steps were carried out by the method of Example 5 to obtain catalyst 7. The reaction results are shown in Table 1.

Example 8

Except that the surfactants of A and B were changed to 20.0 g of NP-7, other steps were carried out by the method of Example 1, and the obtained catalyst number was 8. The reaction results are shown in Table 1.

Example 9

Except that the surfactants of A and B were changed to nonylphenol polyoxyethylene ether-10 (NP-10) with a mass of 20.0 g, other steps were carried out by the method of Example 5, and the catalyst number obtained was 9. The reaction results are shown in Table 1.

Example 10

Except that the surfactants of A and B were changed to nonylphenol polyoxyethylene ether-4 (NP-4) with a mass of 20.0 g, other steps were carried out by the method of Example 5, and the obtained catalyst number was 10. The reaction results are shown in Table 1.

Table 1: Benzene selective hydrogenation activity of each catalyst

catalyst Maximum yield/% Conversion rate 40% selectivity/% Conversion rate 40% TOF(H₂)/h^-1 Example 1 42.2 75.8 2856 Comparative Example 1 2.1^[1] - 270^[1] Example 2 13.3 31.9 3031 Example 3 12.9 32.1 1760 Example 4 3.3 8.2 2768 Example 5 44.8 74.2 3560 Example 6 35.9 68.4 2931 Example 7 34.9 63.8 3659 Example 8 18.6 39.1 3256 Example 9 41.6 67.9 6924 Example 10 23.3 42.8 6613

Note: [1] The conversion rate is 13.9%.

Example 11

Except that the zinc sulfate in Example 5 was changed to 1.04% ferrous sulfate in mass ratio, other steps were carried out by the method of Example 5, and the obtained catalyst number was 11. The reaction results are shown in Table 2.

Example 12

Except that the zinc sulfate in Example 5 was changed to 1.04% manganese chloride by mass ratio, other steps were carried out by the method of Example 5, and the obtained catalyst number was 12. The reaction results are shown in Table 2.

Example 13

Except that the zinc sulfate in Example 5 was changed to 1.04% cobalt sulfate by mass ratio, other steps were carried out by the method of Example 5, and the catalyst number obtained was 13. The reaction results are shown in Table 2.

Example 14

Except that the zinc sulfate in Example 5 was changed to 1.04% copper sulfate in mass ratio, other steps were carried out by the method of Example 5, and the catalyst number obtained was 14. The reaction results are shown in Table 2.

Example 15

Except that the zinc sulfate in Example 5 was changed to chromium nitrate with a mass ratio of 1.04%, other steps were carried out by the method in Example 5, and the obtained catalyst number was 15. The reaction results are shown in Table 2.

Example 16

Except that the zinc sulfate in Example 5 was changed to 1.04% nickel chloride by mass ratio, other steps were carried out by the method of Example 5, and the catalyst number obtained was 16. The reaction results are shown in Table 2.

Table 2: The benzene selective hydrogenation activity of each catalyst of embodiment 11-16

Catalyst Maximum yield/% Conversion rate 40% selectivity/% Conversion rate 40% TOF(H₂)/h^-1 Example 11 39.1 70.8 2654 Example 12 27.3 50.8 2934 Example 13 22.5 44.6 3303 Example 14 18.9 38.5 2254 Example 15 34.3 65.5 2879 Example 16 28.9 48.9 2944

Examples 17-22

Except that the oil and surfactant in the solvent composition of Example 1 were changed as shown in Table 3, other steps were as shown in Example 1, and the reaction results are shown in Table 4.

Table 3: Each catalyst solvent composition of embodiment 17-22

Example 17 18 19 20 twenty one twenty two Oil 1:1 volume ratio of pentane and butanol solution 1:1 volume ratio of pentane and butanol solution 1:1 volume ratio of pentane and butanol solution 1:1 volume ratio of pentane and butanol solution 1:1 volume ratio of pentane and butanol solution 1:1 volume ratio of pentane and butanol solution

Surfactant Sodium dodecyl sulfate Sodium bis(2-ethylhexyl)succinate Cetyl Trisorbitan Methyl Ammonium Bromide Fatty Acid Ester Polyoxyethylene Ether Pentadecyl polyoxyethylene ether Pentadecyl polyoxyethylene ether

Table 4: The benzene selective hydrogenation activity of each catalyst of embodiment 17-22

Catalyst Maximum yield/% Conversion rate 40% selectivity/% Conversion rate 40% TOF(H₂)/h^-1 Example 17 22.4 44.3 2273 Example 18 19.8 39.8 2435 Example 19 24.3 46.1 1246 Example 20 27.5 50.4 2451 Example 21 15.5 35.4 3105 Example 22 20.4 38.2 1475

Examples 23-27

Except that the oil and surfactant in the solvent composition of Example 1 were changed as shown in Table 5, other steps were as shown in Example 1, and the reaction results are shown in Table 6.

Table 5: Each catalyst solvent composition of embodiment 23-27

Example twenty three twenty four 25 26 27 Oil 1:1 volume ratio of pentane and octanol solution 1:1 volume ratio of pentane and pentanol solution 1:1 volume ratio of pentane and hexanol solution 1:1 volume ratio of pentane and butanol solution 1:1 volume ratio of pentane and octanol solution Surfactant NP-7 NP-7 NP-7 NP-7 NP-7

Table 6: The benzene selective hydrogenation activity of each catalyst of embodiment 23-27

Catalyst Maximum yield/% Conversion rate 40% selectivity/% Conversion rate 40% TOF(H₂)/h^-1 Example 23 18.4 37.3 1953 Example 24 27.3 46.9 2929 Example 25 23.5 44.0 1965 Example 26 27.5 48.8 3021 Example 27 22.1 40.5 2223

Examples 28-33

Except that the oil and surfactant in the solvent composition of Example 1 were changed as shown in Table 7, other steps were as shown in Example 1, and the reaction results are shown in Table 8.

Table 7: Each catalyst solvent composition of embodiment 28-33

Example 28 29 30 31 Oil 1:1 volume ratio of hexane and pentanol solution 1:1 volume ratio of benzene and amyl alcohol solution The volume ratio is 1:1 toluene and pentanol solution The volume ratio is 1:1 xylene and amyl alcohol solution Surfactant NP-7 NP-7 NP-7 NP-7 Example 32 33 Oil The volume ratio is 1:1 n-octane and pentanol solution The volume ratio is 1:1 heptane and pentanol solution Surfactant NP-7 NP-7

Table 8: The benzene selective hydrogenation activity of each catalyst of embodiment 28-33

Catalyst Maximum yield/% Conversion rate 40% selectivity/% Conversion rate 40% TOF(H₂)/h^-1 Example 28 11.5 22.5 2654 Example 29 34.2 61.5 3001 Example 30 27.8 44.2 2231 Example 31 33.5 62.1 2054 Example 32 29.8 45.1 2708 Example 33 25.6 43.4 2616

Claims (4)

1. preparation method who is used for the benzene selective hydrogenation catalysts, the expression formula of this catalyst is

Ru-M-B/SiO ₂

Wherein: M is one or several of Cr, Mn, Fe, Co, Ni, Cu or Zn;

Its preparation process is:

A) with Ru: M: H ₂The mass ratio preparation of O=1: 0-2: 4-20 contains the aqueous solution of ruthenium;

B) by this aqueous solution: oil: surfactant: the mass ratio of cosurfactant=1: 10-50: 5-50: 0-20 mixes, and stirring at room obtains solution A;

C) be mixed with solution B with surfactant, oil and reductant solution, wherein reducing agent is potassium borohydride, formaldehyde or hydrazine hydrate; Three's mass ratio is respectively 10-50% oil in this solution, 5-50% surfactant, the solution of potassium borohydride of 5-20%;

D) mixed solution A, B under 3-40 ℃ of stirring add ethyl orthosilicate, and the 4-49 that its addition is counted ruthenium with silica doubly adds ammoniacal liquor and precipitates, and the separated and collected sediment obtains catalyst;

Described ruthenium precursor is ruthenium trichloride, acetylacetonate ruthenium or nitric acid ruthenium;

Described oil is cyclohexane, pentane, hexane, normal octane, benzene,toluene,xylene, heptane, hexanol, amylalcohol, butanols or octanol.

Described surfactant is dodecyl sodium sulfate, two (2-ethylhexyl) sodium succinate, softex kw, NPE, sorbitan fatty acid ester APEO or pentadecyl APEO;

Described cosurfactant is one or several of Cr, Mn, Fe, Co, Ni, Cu or Zn.

2. the preparation method of claim 1 is characterized in that, described ruthenium precursor is a ruthenium trichloride.

3. the preparation method of claim 1, it is characterized in that described surfactant is dodecyl sodium sulfate, two (2-ethylhexyl) sodium succinate, softex kw, NPE, sorbitan fatty acid ester APEO or pentadecyl APEO.

4. the preparation method of claim 1 is characterized in that, described reducing agent is potassium borohydride, formaldehyde or hydrazine hydrate aqueous solution, quality percentage composition 2-10%.