Catalyst for benzene hydroxylation for preparation of phenol and preparation method thereof

Abstract

The invention relates to a catalyst for benzene hydroxylation for preparation of phenol and a preparation method thereof, wherein said catalyst uses a mesoporous material as carrier, and the catalyst is prepared by first modifying the surface of the carrier using aminosilane, then immersing with acetylacetonate salt of metal, and finally washing and drying. Advantage of the invention is that a reactive metal is loaded on the silane-modified mesoporous material to form a homogeneous-heterogeneous composite catalyst, wherein, the reactive metal component is present in a reaction system in a homogeneous form, which ensures high catalytic performance of the catalyst component, and it is loaded on the carrier through bridging action of aminosilane, which improves the acting force between the metal component and the carrier, enhances stability of the catalyst, and facilitates separation of the catalyst from the product. The catalyst has a simple preparation process, has excellent catalytic performance, and can be applied to the reaction system of benzene hydroxylation for preparation of phenol.

Claims

1. A method for preparing a catalyst for benzene hydroxylation for preparation of phenol, wherein the catalyst comprises a carrier being a mesoporous material SBA-16, SBA-16 or MC M-41 with its channel surface functionally modified using aminosilane, and a reactive component being palladium, platinum, copper, vanadium, iron or zinc; wherein the catalyst is a homogeneous-heterogeneous composite catalyst; and wherein the reactive component is loaded onto the carrier through bridging action of the aminosilane, the method comprising the following steps: A. carrier surface modification process: immersing the carrier into an aminosilane solution with a concentration of 0.1-2 g/L, performing surface modification at a temperature of 20-40° C. taking out, washing and air drying; B. immersion process: immersing the modified carrier obtained from the step A into acetylacetonate solution containing the reactive component at a temperature of 20-40° C. for 6-36 hours; wherein the acetylacetonate solution has a concentration of 0.1-0.25 mol/L; and C. washing and drying process: washing the catalyst obtained from the step B with absolute ethanol or dichloromethane and drying wherein the temperature used in both the method steps A and B does not exceed 40° C.

2. The preparation method according to claim 1, wherein in the step A the aminosilane is γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, or N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; the solvent is dichloromethane, toluene or absolute ethanol; and the modification time is 1-32 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is X-ray diffraction diagrams of SBA-15 carrier, V/NH.sub.2-SBA-15 (Example 1) catalyst and vanadiumoxy acetylacetonate (VO(C.sub.5H.sub.7O.sub.2).sub.2) precursor.

(2) FIG. 2 is infrared characterization diagrams of SBA-15, NH.sub.2-SBA-15 (Example 1), VO(C.sub.5H.sub.7O.sub.2).sub.2 and V/NH.sub.2-SBA-15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) Effects of the catalyst and the preparation method of the invention are further illustrated below through Examples.

Example 1 Preparation of V/NH.SUB.2.-SBA-15 Catalyst

(4) 2 g of SBA-15 is dispersed in 50 ml of dichloromethane solvent, and 0.05 g of aminosilane KH550 is added, stirred at 25° C., immersed for 1 h, washed with absolute ethanol, filtered and then dried to obtain NH.sub.2-SBA-15 powder. 1.33 g of VO(C.sub.5H.sub.7O.sub.2).sub.2 (molecular weight of 265.15) is added to 50 ml of CH.sub.2Cl.sub.2, and stirred. After the solid is completely dissolved, 1.5 g of the NH.sub.2-SBA-15 powder is added, stirred at 40° C., filtered after 12 h of immersion, washed with absolute ethanol, and dried at 90° C. to obtain V/NH.sub.2-SBA-15 catalyst.

(5) FIG. 1 shows the analysis result of X-ray diffraction of the V/NH.sub.2-SBA-15 catalyst. SBA-15 has a strong peak at 22°, corresponding to amorphous Si. V/NH.sub.2-SBA-15 presents characteristic peaks of VO(C.sub.5H.sub.7O.sub.2).sub.2 and Si, which indicates that the catalyst component has been loaded on the SBA-15 carrier.

(6) From FIG. 2, the peak at 960 cm.sup.−1 corresponds to Si—OH. The strength of V/NH.sub.2-SBA-15 significantly decreases at 960 cm.sup.−1, which is due to silane functionalization of the carrier and loading of VO(C.sub.5H.sub.7O.sub.2).sub.2. Furthermore, it can be found by comparing c and a that c has additional two peaks at 2930 and 2848 cm.sup.−1, which correspond to C—H stretching vibration, while 1557 cm.sup.−1 corresponds to bending vibration, which indicates that silane is grafted onto the surface of SBA-15 through a chemical bond.

(7) The catalyst is used in a system for preparation of phenol by benzene hydroxylation. After 6 h of reaction, the yield of phenol is 4.5%. After the catalyst is used for 5 times, the catalytic efficiency is reduced to 70% of that of fresh catalyst.

Example 2 Preparation of V/NH.SUB.2.-MCM-41 Catalyst

(8) 2 g of MCM-41 is dispersed in 50 ml of dichloromethane solvent, and 0.1 g of aminosilane KH792 is added, stirred at 20° C., immersed for 8 h, washed with absolute ethanol, filtered and then dried to obtain NH.sub.2-MCM-41 powder. 3.31 g of VO(C.sub.5H.sub.7O.sub.2).sub.2 (molecular weight of 265.15) is added to 50 ml of CH.sub.2Cl.sub.2, and stirred. After the solid is completely dissolved, 1.5 g of the NH.sub.2-MCM-41 powder is added, stirred at 20° C., filtered after 6 h immersion, washed with absolute ethanol, and dried at 90° C. to obtain V/NH.sub.2-MCM-41 catalyst.

(9) The catalyst is used in a system for preparation of phenol by benzene hydroxylation, and after 6 h of reaction, the yield of phenol is 3.9%. After the catalyst is used for 5 times, the catalytic efficiency is reduced to 62% of that of fresh catalyst.

Example 3 Preparation of Pd/NH.SUB.2.-SBA-15 Catalyst

(10) 2 g of SBA-15 is dispersed in 50 ml of dichloromethane solvent, and 0.05 g of aminosilane KH550 is added, stirred at 40° C., immersed for 24 h, washed with absolute ethanol, filtered and then dried to obtain NH.sub.2-SBA-15 powder. 3.05 g of Pd(C.sub.5H.sub.7O.sub.2).sub.2 (molecular weight of 304.64) is added to 50 ml of CH.sub.2Cl.sub.2, and stirred. After the solid is completely dissolved, 1.5 g of the NH.sub.2-SBA-15 powder is added, stirred at 40° C., filtered after 36 h of immersion, washed with absolute ethanol, and dried at 90° C. to obtain Pd/NH.sub.2-SBA-15 catalyst.

(11) The catalyst is used in a system for preparation of phenol by benzene hydroxylation, and after 6 h of reaction, the yield of phenol is 2.5%. After the catalyst is used for 5 times, the catalytic efficiency is reduced to 60% of that of fresh catalyst.

Example 4 Preparation of Cu/NH.SUB.2.-SBA-16 Catalyst

(12) 2 g of SBA-16 is dispersed in 50 ml of dichloromethane solvent, and 0.005 g of silane coupling agent 602 is added, stirred at 30° C., immersed for 32 h, washed with absolute ethanol, filtered and then dried to obtain NH.sub.2-SBA-16 powder. 1.96 g of Cu(C.sub.5H.sub.7O.sub.2).sub.2 (molecular weight of 261.76) is added to 50 ml of CH.sub.2Cl.sub.2, and stirred. After the solid is completely dissolved, 1.5 g of the NH.sub.2-SBA-16 powder is added, stirred at 25° C., filtered after 12 h of immersion, washed with absolute ethanol, and dried at 90° C. to obtain Cu/NH.sub.2-SBA-16 catalyst.

(13) The catalyst is used in a system for preparation of phenol by benzene hydroxylation, and after 6 h of reaction, the yield of phenol is 3.1%. After the catalyst is used for 5 times, the catalytic efficiency is reduced to 65% of that of fresh catalyst.