Method for preparing phenol from benzene

Abstract

The invention relates to a method for preparing phenol from benzene. According to the method, a bimetallic composite oxide is used as a catalyst, oxygen is used as an oxidant, acetonitrile is used as a solvent, ascorbic acid is used as a reducing agent, and benzene is converted into phenol. The preparation method of the bimetallic composite oxide catalyst comprises the following steps: mixing a trivalent metal M < 3 + >-containing salt, a divalent metal Z < 2 + >-containing salt, NaOH and Na2CO3 according to a certain ratio, fully and uniformly grinding, standing for crystallization, washing with deionized water to be neutral, drying and grinding, and roasting in air to obtain the final catalyst. The method provided by the invention has the advantages of high efficiency, simple catalyst preparation method, low cost and the like.

Description

Technical Field

[0001] The invention belongs to the field of organic chemistry, and particularly relates to a method for preparing phenol from benzene. Background Art

[0002] Phenol is a very important chemical raw material. It is mainly used in the industry to produce chemical products and intermediates such as bisphenol A, phenolic resin, adipic acid, caprolactam, aniline, cyclohexanone, etc. At present, the methods for industrial production of phenol include cumene method, sulfonation method, cyclohexanone-cyclohexanol method, chlorobenzene hydrolysis method and toluene-benzoic acid method. Among them, nearly 90% of phenol in the world is prepared by cumene method. In my country, 85%-90% of industrial phenol is produced by cumene method, and the rest is mainly produced by sulfonation method. However, the cumene method has the following shortcomings, including: 1. The atomic utilization rate is only 61.8%; 2. The process flow is complicated, and the intermediate product cumene peroxide is easily decomposed by heat, acid and alkali, and the strong heat release during the decomposition process is easy to cause explosion; 3. The supply and demand of phenol and acetone are unbalanced, and the commercial value of phenol is restricted by acetone; 4. The yield of phenol is low, only 5%; 5. The purification process is energy-intensive. Other industrially used methods for preparing phenol, such as sulfonation, toluene-benzoic acid, chlorobenzene hydrolysis, cyclohexanone-cyclohexanol, etc., mostly have disadvantages such as high energy consumption, long process, and serious pollution, which do not meet the requirements of green chemistry and green technology. With the popularization of green chemistry, people have begun to study the synthesis route of phenol from the aspects of improving the atomic utilization rate of the reaction and green chemistry, hoping to improve the problems of traditional phenol preparation methods such as long process, high energy consumption, low yield, and serious pollution. Therefore, direct oxidation of benzene to prepare phenol has become a research hotspot for green preparation of phenol.

[0003] At present, the oxidants used for direct oxidation of benzene to produce phenol include H2O2, N2O and O2. Among them, H2O2, as an efficient and green oxidant, has shown advantages in the preparation of phenol from benzene oxidation and has been widely studied. At present, the catalysts used for the preparation of phenol from benzene oxidation using H2O2 as an oxidant mainly include molecular sieve catalysts, metal-supported catalysts and heteropolyacid catalysts. However, H2O2 is a flammable and explosive chemical reagent, which is unstable and has low safety. At the same time, it is corrosive, so it has high requirements for storage and transportation, which increases the production cost of phenol. In addition, H2O2 is slightly expensive and does not have the cost advantage of oxygen as an oxidant.

[0004] Oxygen, as a green oxidant, has less environmental pollution from the byproducts of its oxidation reaction, and oxygen is cheaper and more readily available than H2O2, so oxygen oxidation of benzene is considered to be the most likely green preparation route for the industrialization of phenol. At present, there are relatively few reports on the direct oxidation of benzene by oxygen to prepare phenol, and the catalyst used is mainly a vanadium-based catalyst, such as the mesoporous material SBA-15 that uses aminosilane to functionally modify the pore surface in patent CN103537313B as a carrier, with vanadium acetylacetonate as an active component, and the active component is loaded on the mesoporous material modified by aminosilane by an impregnation method, and a homogeneous-heterogeneous composite catalyst is prepared, and after reacting for 6h, the best yield of phenol is 4.5%. CN103878012A uses V (IV) oxide material loaded by SBA-15 as a catalyst, and uses oxygen as an oxygen source, and the best yield of phenol is 2.8%. Yuichi Ichihashi et al. [Y. Ichihashi, T. Taniguchi, H. Amano, T. Atsumi, S. Nishiyama, S. Tsuruya. Liquid-phase oxidation of benzene to phenol by molecular oxygen over La catalysts supported on HZSM-5. Top Catal 2008 (47) 98-100.] used HZSM-5 as a carrier and loaded 0.5 wt% lanthanum oxide as a catalyst for preparing phenol from benzene oxidation. Under the reaction conditions of 80°C and 0.4 MPa of O2, the optimal yield of phenol reached 4.2%. However, these catalysts prepared with molecular sieves as carriers not only have relatively expensive raw material prices, but also have the disadvantages of high temperature, complex steps, long preparation cycle, and low product yield. Patent CN102850154A discloses a catalyst synthesized with noble metals, metal oxides and titanium silicon molecular sieves as components, which directly oxidizes benzene to prepare phenol using molecular oxygen under the promotion of CO, and obtains a higher benzene conversion rate and phenol selectivity. However, the preparation process of this catalyst is very complicated and the cost of the raw materials used is also very high. Therefore, it is of great significance to develop a highly efficient, simple and low-cost catalyst for direct oxidation of benzene with oxygen to produce phenol. Summary of the invention

[0005] In order to solve the problems of complicated catalyst synthesis steps, high preparation cost or low phenol yield in the existing benzene oxidation technology for preparing phenol, the present invention provides a method for preparing phenol from benzene and a method for preparing a bimetallic composite oxide catalyst used in the method.

[0006] The present invention relates to a method for preparing phenol from benzene, and the prepared bimetallic composite oxide catalyst is used in the direct oxidation of benzene by oxygen to prepare phenol. In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] The preparation method of the bimetallic composite oxide catalyst comprises the following steps:

[0008] 1): Containing trivalent metal M 3+ Metal salts and divalent metal Z 2+ The metal salts are mixed in a molar ratio of 1:6 to 6:1 and then fully ground to be uniform.

[0009] 2): Add NaOH and Na2CO3 in a molar ratio of 16:1 to the material obtained in step 1) and grind them thoroughly and evenly.

[0010] 3): The material obtained in step 2) is placed at 20-50°C for crystallization for 4-24 hours, and then washed with deionized water until neutral.

[0011] 4): The material obtained in step 3) is dried in a normal pressure oven at 40-100°C, fully ground and then calcined at 300-600°C.

[0012] The bimetallic composite oxide catalyst used for direct oxidation of benzene to prepare phenol is prepared by adopting the above preparation method.

[0013] The above step 1) contains a trivalent metal M 3+ Metal salts and divalent metal Z 2+ The molar ratio of the metal salt is preferably 1:3 to 3:1.

[0014] Furthermore, containing M 3+ The metal salt is selected from one of Fe(NO3)3·9H2O, FeCl3·6H2O, Al(NO3)3·9H2O, Ce(NO3)3·6H2O, CeCl3·6H2O, Cr(NO3)3·9H2O;

[0015] Furthermore, containing Z 2+ The metal salt is selected from one of Cu(NO3)2·3H2O, CuSO4·5H2O, CuCl2·2H2O, Zn(NO3)2·6H2O, ZnSO4·7H2O, Co(NO3)2·6H2O, CoSO4·7H2O, CoCl2·6H2O, Ni(NO3)2·6H2O, and NiSO4·6H2O.

[0016] Preferably, x=3, y=1, z=4.5 or x=2, y=1, z=3.5 or x=1, y=3, z=5.5 or x=1, y=2, z=4.

[0017] Cu(NO3)2·3H2O and Al(NO3)3·9H2O are preferred for the synthesis of catalyst Cu x Al y O (2x+3y) / 2 Cu3Al1O 4.5 ;

[0018] Cu(NO3)2·3H2O and Fe(NO3)3·9H2O are preferred for the synthesis of catalyst Cu x Fe y O (2x+3y) / 2 Cu3Fe1O 4.5 ;

[0019] Cu(NO3)2·3H2O and Ce(NO3)3·6H2O are preferred for the synthesis of catalyst Cu x Ce y O (2x+3y) / 2 Cu3Ce1O 4.5 ;

[0020] CuSO4·5H2O and FeCl3·6H2O are preferred for the synthesis of catalyst Cu x Fe y O (2x+3y) / 2 Cu2Fe1O 3.5 ;

[0021] Preferred Zn(NO3)2·6H2O and Al(NO3)3·9H2O synthesis catalyst Zu x Al y O (2x+3y) / 2 Zn1Al3O 5.5 ;

[0022] Co(NO3)2·6H2O and Al(NO3)3·9H2O are preferred for the synthesis of catalyst Co x Al y O (2x+3y) / 2 Co1Al3O 5.5 ;

[0023] CuSO4·5H2O and Cr(NO3)3·9H2O are preferred for the synthesis of catalyst Cu x Cr y O (2x+3y) / 2 Cu3Cr1O 4.5 ;

[0024] Cu(NO3)2·3H2O and Al(NO3)3·9H2O are preferred for the synthesis of catalyst Cu x Cr y O (2x+3y) / 2 It is Cu1Al2O4.

[0025] Furthermore, in step 3), the crystallization temperature is preferably 25 to 35° C., and the crystallization time is preferably 10 to 12 h;

[0026] In step 4), the drying temperature is preferably 60 to 80° C., and the drying time is preferably 10 to 12 hours;

[0027] Furthermore, in step 4), the calcination temperature is preferably 350-450° C., and the calcination time is preferably 4-6 hours.

[0028] Benzene is directly oxidized to phenol using the bimetallic composite oxide prepared as above as catalyst, oxygen as oxidant, acetonitrile as solvent and ascorbic acid as reducing agent.

[0029] Beneficial Effects

[0030] Compared with the existing technology of preparing phenol by oxidizing benzene with oxygen, the method provided by the present invention has the advantages of high efficiency, simple catalyst preparation method and low cost, and the best phenol yield reaches 6.7%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Example 2 X-ray diffraction pattern of Cu1Al2O4 catalyst

[0032] Figure 2 Liquid chromatogram for qualitative analysis of benzene and phenol

[0033] Figure 3 Example 1 Cu3Al1O 4.5 Results of the reaction of benzene to phenol under the action of catalyst DETAILED DESCRIPTION

[0034] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0035] Embodiment 1:

[0036] Weigh 14.46g of Cu(NO3)2·3H2O and 7.50g of Al(NO3)3·9H2O (the molar ratio of Cu to Al is 3:1), mix them evenly, add 6.40g of NaOH and 1.06g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 12h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in a 60℃ atmospheric pressure oven for 12h, take it out and grind it into powder, and calcine it in a 350℃ muffle furnace for 6h to obtain a Cu-Al bimetallic composite oxide catalyst, marked as Cu3Al1O 4.5 .

[0037] Embodiment 2:

[0038] Weigh 4.82g of Cu(NO3)2·3H2O and 15.0g of Al(NO3)3·9H2O (the molar ratio of Cu to Al is 1:2), mix them evenly, add 5.69g of NaOH and 0.942g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 12h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in a 60℃ atmospheric pressure oven for 12h, take it out and grind it into powder, and roast it in a 350℃ muffle furnace for 6h to obtain a Cu-Al bimetallic composite oxide catalyst, marked as Cu1Al2O4. Figure 1 The X-ray diffraction pattern of Cu1Al2O4 catalyst in Example 2 is shown in Figure 2. The instrument used in the X-ray diffraction method is a Japanese RIGAKUD / MAX 250 / PC X-ray powder diffractometer, and the radiation and parameters used are Cu Kα radiation (λ=0.15406nm), graphite monochromator, tube voltage 40kV, tube current 100mA, and scanning step length 0.02° / s.

[0039] Embodiment 3:

[0040] Weigh 14.46g of Cu(NO3)2·3H2O and 8.08g of Fe(NO3)3·9H2O (the molar ratio of Cu to Fe is 3:1), mix them evenly, add 6.40g of NaOH and 1.06g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 12h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in a 60℃ atmospheric pressure oven for 12h, take it out and grind it into powder, and calcine it in a 350℃ muffle furnace for 6h to obtain a Cu-Fe bimetallic composite oxide catalyst, which is marked as Cu3Fe1O 4.5 .

[0041] Embodiment 4:

[0042] Weigh 14.46g of Cu(NO3)2·3H2O and 8.68g of Ce(NO3)3·6H2O (the molar ratio of Cu to Ce is 3:1), mix them evenly, add 6.40g of NaOH and 1.06g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 12h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in a 60℃ atmospheric pressure oven for 12h, take it out and grind it into powder, and calcine it in a 350℃ muffle furnace for 6h to obtain a Cu-Ce bimetallic composite oxide catalyst, marked as Cu3Ce1O 4.5 .

[0043] Embodiment 5:

[0044] Weigh 12.48g of CuSO4·5H2O and 6.76g of FeCl3·6H2O (the molar ratio of Cu to Fe is 2:1), mix them evenly, add 6.22g of NaOH and 1.03g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 10h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in an oven at 80℃ for 12h, take it out and grind it into powder, and calcine it in a muffle furnace at 400℃ for 5h to obtain a Cu-Fe bimetallic composite oxide catalyst, which is marked as Cu2Fe1O 3.5 .

[0045] Embodiment 6:

[0046] Weigh 5.95g of Zn(NO3)2·6H2O and 22.51g of Al(NO3)3·9H2O (the molar ratio of Zn to Al is 1:3), mix them evenly, add 7.82g of NaOH and 1.30g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 12h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in an oven at 80℃ for 10h, take it out and grind it into powder, and calcine it in a muffle furnace at 350℃ for 5h to obtain a Zn-Al bimetallic composite oxide catalyst, marked as Zn1Al3O 5.5 .

[0047] Embodiment 7:

[0048] Weigh 5.82g of Co(NO3)2·6H2O and 22.51g of Al(NO3)3·9H2O (the molar ratio of Co to Al is 1:3), mix them evenly, add 7.82g of NaOH and 1.30g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 12h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in a 60℃ atmospheric pressure oven for 12h, take it out and grind it into powder, and calcine it in a 350℃ muffle furnace for 6h to obtain a Cu-Al bimetallic composite oxide catalyst, marked as Co1Al3O 5.5 .

[0049] Embodiment 8:

[0050] Weigh 14.98g of CuSO4·5H2O and 4.76g of Cr(NO3)3·9H2O (the molar ratio of Cu to Cr is 3:1), mix them evenly, add 6.40g of NaOH and 1.0599g of Na2CO3, grind them evenly, and let them stand for crystallization at room temperature for 12h. Then, take out the crystallized solid, wash it with deionized water until it is neutral, dry it in a 60℃ atmospheric pressure oven for 12h, take it out and grind it into powder, and calcine it in a muffle furnace at 350℃ for 6h to obtain a Cu-Al bimetallic composite oxide catalyst, marked as Cu3Cr1O 4.5 .

[0051] Embodiment 9:

[0052] The above embodiment was applied to the reaction of preparing phenol by oxidation of benzene with oxygen, that is, 400 mg of catalyst, 4 mL of benzene, 12 mL of acetonitrile and 1.6 g of ascorbic acid were added to a 100 mL high pressure reactor, 2.0 MPa of O2 was introduced, magnetic stirring was performed, and the reaction was carried out at 80°C for 3 h. The results are shown in the following table.

[0053] Figure 2 This is the liquid chromatogram for qualitative analysis of benzene and phenol. Figure 3 For example 1 Cu3Al1O 4.5 The results of the reaction of benzene to phenol under the action of catalyst.

[0054] The liquid chromatography analysis conditions are as follows:

[0055] A Shimadzu LC-20AT liquid chromatograph was used, with a mobile phase of acetonitrile: deionized water = 1:1, a mobile phase flow rate of 0.9 mL / min, a C18 column, a column temperature of 35°C, an injection volume of 5 μL, and a detection UV wavelength of 254 nm.

[0056]

[0057]

Claims

1. A catalyst for preparing phenol, characterized in that: A bimetallic composite oxide catalyst is used, wherein the bimetallic composite oxide catalyst is composed of three elements, including a trivalent metal element M 3+ , a divalent metal element Z 2+ and oxygen element; the catalyst has the following general formula (I): (M 2+ ) x (From 3+ ) y About z in x / y=1:3~3:1 z=(2x+3y) / 2 The trivalent metal M 3+ Selected from Fe 3+ 、Al 3+ 、Ce 3+ Cr 3+ One of the following; The divalent metal Z 2+ Selected from Cu 2+ 、Zn 2+ 、Co 2+ 、Ni 2+ One of the.

2. The catalyst according to claim 1, characterized in that: In step 1), M 3+ The metal salt is selected from one of Fe(NO3)3·9H2O, FeCl3·6H2O, Al(NO3)3·9H2O, Ce(NO3)3·6H2O, CeCl3·6H2O, Cr(NO3)3·9H2O, and / or contains Z 2+ The metal salt is selected from one of Cu(NO3)2·3H2O, CuSO4·5H2O, CuCl2·2H2O, Zn(NO3)2·6H2O, ZnSO4·7H2O, Co(NO3)2·6H2O, CoSO4·7H2O, CoCl2·6H2O, Ni(NO3)2·6H2O, and NiSO4·6H2O.

3. The catalyst according to claim 1, characterized in that: x=3, y=1, z=4.5 or x=2, y=1, z=3.5 or x=1, y=3, z=5.5 or x=1, y=2, z=4.

4. The catalyst according to claim 1 or 3, characterized in that: The bimetallic composite oxide catalyst is Cu3A11O 4.5 、Cu3Fe1O 4.5 、Cu3Ce1O 4.5 、Cu2Fe1O 3.5 、Zn1Al3O 5.5 、Co1Al3O 5.5 , Cu1Al2O4 or Cu3Cr1O 4.5 .

5. A method for preparing a catalyst for preparing phenol, characterized in that: The steps include: 1) Weigh the M 3+ Metal salts and Z 2+ The metal salts are mixed evenly; 2) adding NaOH and Na2CO3 in a molar ratio of 16:1 in step 1) and grinding thoroughly; 3) allowing the material obtained in step 2) to stand for crystallization, and then washing with deionized water until it is neutral; 4) Drying the material obtained in step 3), grinding it into powder, and calcining it in air to obtain a bimetallic composite oxide catalyst.

6. The preparation method according to claim 4, characterized in that: In step 1), M 3+ The metal salts and Z 2+ The molar ratio of the metal salt is 1:3 to 3:

1.

7. The preparation method according to claim 4, characterized in that: In step 2), the molar ratio of NaOH to Na2CO3 is 16:1, and the molar number of total sodium ions is 3+ The molar number of metal salt is three times that of Z 2+ The sum of twice the number of moles of metal salt.

8. The preparation method according to claim 4, characterized in that: In step 3), the temperature for standing crystallization is 25 to 35° C. and the time is 10 to 12 hours.

9. The preparation method according to claim 4, characterized in that: In step 4), the drying temperature is 60-80°C for 10-12 hours, and the calcination temperature in air is 350-450°C for 4-6 hours.

10. A method for preparing phenol, characterized in that: Under the action of the catalyst described in any one of claims 1 to 4 or the catalyst prepared by any one of claims 5 to 9, acetonitrile is used as a solvent, ascorbic acid is used as a reducing agent, and oxygen is used to directly oxidize benzene to obtain phenol.

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