Layered catalyst, preparation method and application

Abstract

The invention provides a layered catalyst as well as a preparation method and application thereof. The layered catalyst is prepared by synthesizing a layered titanium oxide by adopting a high-temperature solid-phase synthesis method and then adjusting the acid-base property of the surface of the catalyst through proton exchange. The layered catalyst has a relatively large specific surface area, relatively strong acidic sites and relatively high hydration catalytic activity, and can significantly improve the catalytic efficiency of cyclohexene hydration. The preparation method of the layered catalyst is simple, high in operability and convenient for large-scale industrial production. The catalytic efficiency of the layered catalyst for catalyzing cyclohexene to prepare cyclohexanol reaches about 14%.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts and relates to a layered catalyst, a preparation method and an application thereof. Background Art

[0002] Cyclohexanol is a colorless, transparent oily liquid or white needle-shaped crystals. It is an organic compound mainly used in the production of adipic acid, hexamethylenediamine, cyclohexanone, caprolactam, etc.

[0003] The main methods for producing cyclohexanol are cyclohexene hydration, phenol hydrogenation and cyclohexane oxidation. Among them, cyclohexene hydration can be traced back to 1980 and is a method for synthesizing cyclohexanol with excellent technology. The methods for producing cyclohexanol by cyclohexene hydration include direct hydration and indirect hydration. The catalyst used in the direct hydration method is a ZSM-5 molecular sieve with a ten-membered pore structure. The catalytic efficiency of the ZSM-5 molecular sieve can reach 7.5%, and its selectivity can reach 99.2%. However, from the perspective of industrial application, the catalytic activity of the catalyst used in the cyclohexene hydration method is low, and there is still a lot of room for development. Summary of the invention

[0004] The purpose of the present invention is to provide a layered catalyst, a preparation method and an application thereof, so as to solve the problem that the catalytic activity of the catalyst used in the existing cyclohexene hydration method is low.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a layered catalyst, which is layered H2TiO3 or layered M2TiO3, wherein M includes one or more of Al, Fe, Zn and Nb.

[0006] The present application provides a method for preparing a layered catalyst, comprising: S01: Mix and grind Na2CO3 and TiO2 evenly, calcine at 800-1200°C for 10 hours, and grind to obtain the precursor Na2TiO3 after cooling.

[0007] Weigh Na2CO3 and TiO2 in a mass ratio of 1:2-1:5, mix and grind the weighed Na2CO3 and TiO2 evenly, and place them in a corundum crucible. Calcine them in a muffle furnace at a temperature of 800-1200℃ for 10 h. After cooling, grind to obtain the precursor Na2TiO3.

[0008] S02: Place the precursor Na2TiO3 in an acidic aqueous solution or a salt solution, stir for 10 days, centrifuge, wash to neutrality, vacuum dry at 60-100°C for 10 hours, and grind after cooling to obtain layered H2TiO3 or M2TiO3, wherein M includes one or more of Al, Fe, Zn and Nb.

[0009] Place 5-12g of the precursor Na2TiO3 in 300mL of an acidic aqueous solution or salt solution with a concentration of 5-10mol / L and stir for 10 days. The acidic aqueous solution includes HNO3 or HCl, and the salt solution includes a nitric acid solution or a hydrochloric acid solution of Al, Fe, Zn or Nb.

[0010] After stirring, the mixed solution obtained by centrifugation is washed with deionized water until it is neutral, and then vacuum dried at a temperature of 60-100°C for 10 hours. After cooling, it is ground to obtain layered H2TiO3 or M2TiO3, wherein M includes one or more of Al, Fe, Zn and Nb.

[0011] In addition, the layered catalyst provided in the present application can be used to catalyze the preparation of cyclohexanol from cyclohexene.

[0012] The present invention has the following beneficial effects: (1) The layered catalyst has a large specific surface area, strong acidic sites and high hydration catalytic activity, which can significantly improve the catalytic efficiency of cyclohexene hydration.

[0013] (2) The preparation method of the layered catalyst is simple, highly operable, and convenient for large-scale industrial production.

[0014] (3) The catalytic efficiency of the layered catalyst in preparing cyclohexanol from cyclohexene is about 14%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a SEM (English full name: scanning electron microscope; Chinese name: scanning electron microscope) image of the layered H2TiO3 prepared in Example 1 of the present application; Figure 2 This is a SEM image of layered Fe2TiO5 prepared in Example 2 of the present application; Figure 3 This is a SEM image of the layered Al2TiO5 prepared in Example 3 of the present application; Figure 4 This is a SEM image of layered ZnTiO3 prepared in Example 4 of the present application; Figure 5 This is the SEM image of the precursor Na2TiO3 prepared in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0016] Metal oxides have the advantages of high melting point, strong heat resistance, diverse types, good toxicity resistance, large adjustable range and simple preparation. In terms of catalytic active sites, there are adjustable and variable acidic sites, which have a very significant effect on acid-catalyzed reactions.

[0017] Layered metal oxides are two-dimensional materials with special layered structures and anion intercalation, so they can be used for interlayer adsorption and anion exchange. Most metal oxides are usually blocky structures and need to be prepared into layered structures in a specific way, which can not only greatly increase their specific surface area and improve their adsorption, but also adjust the surface acid-base properties and two-dimensional layered structure of the catalyst, broadening the application field of layered metal oxides.

[0018] Based on the above content, the embodiment of the present application provides a layered catalyst for catalyzing cyclohexene to prepare cyclohexanol. When preparing the layered catalyst, a high-temperature solid-phase synthesis method is used to synthesize a layered titanium oxide, and then the acid-base properties of the catalyst surface are adjusted by proton exchange, so that the layered titanium oxide has a higher cyclohexanol yield in the reaction of catalyzing cyclohexene hydration to obtain cyclohexanol.

[0019] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0020] Example 1 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S101: Weigh Na2CO3 and TiO2 in a mass ratio of 1:3, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 1000°C for 10 h. After cooling, grind to obtain the precursor Na2TiO3.

[0021] S102: Place 10 g of the precursor Na2TiO3 in 300 mL of 6 mol / L HNO3 aqueous solution or salt solution and stir for 10 days. After stirring, wash the mixture obtained by centrifugation with deionized water until it is neutral, dry it in vacuum at 60°C for 10 h, and grind it after cooling to obtain layered H2TiO3.

[0022] Example 2 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S201: Weigh Na2CO3 and TiO2 in a mass ratio of 1:3, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 1000°C for 10 h. After cooling, grind to obtain the precursor Na2TiO3.

[0023] S202: Place 10g of the precursor Na2TiO3 in 300mL of a 6mol / L Fe(NO3)3 aqueous solution and stir for 10 days. After stirring, wash the mixture obtained by centrifugation with deionized water until it is neutral, dry it in vacuum at 60℃ for 10h, and grind it after cooling to obtain layered Fe2TiO5.

[0024] Example 3 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S301: Weigh Na2CO3 and TiO2 in a mass ratio of 1:3, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 1000°C for 10 h. Grind them after cooling to obtain the precursor Na2TiO3.

[0025] S302: 10g of the precursor Na2TiO3 was placed in 300mL of 6mol / L Al(NO3)3 aqueous solution and stirred for 10 days. After stirring, the mixed solution was centrifuged and washed with deionized water until neutral, then vacuum dried at 60℃ for 10h, and ground after cooling to obtain layered Al2TiO5.

[0026] Example 4 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S401: Weigh Na2CO3 and TiO2 in a mass ratio of 1:3, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 1000°C for 10 h. After cooling, grind to obtain the precursor Na2TiO3.

[0027] S402: Place 10g of the precursor Na2TiO3 in 300mL of a 6mol / L Zn(NO3)2 aqueous solution and stir for 10 days. After stirring, wash the mixture obtained by centrifugation with deionized water until it is neutral, dry it in vacuum at 60℃ for 10h, and grind it after cooling to obtain layered ZnTiO3.

[0028] Example 5 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S501: Weigh Na2CO3 and TiO2 in a mass ratio of 1:2, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 800°C for 10 h. After cooling, grind to obtain the precursor Na2TiO3.

[0029] S502: Place 5g of the precursor Na2TiO3 in 300mL of 5mol / L HNO3 aqueous solution and stir for 10 days. After stirring, wash the mixture obtained by centrifugation with deionized water until it is neutral, dry it in vacuum at 80℃ for 10h, and grind it after cooling to obtain layered H2TiO3.

[0030] Example 6 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S601: Weigh Na2CO3 and TiO2 in a mass ratio of 1:5, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 1200°C for 10 h. Grind them after cooling to obtain the precursor Na2TiO3.

[0031] S602: Place 5g of the precursor Na2TiO3 in 300mL of a 10mol / L Fe(NO3)3 solution and stir for 10 days. After stirring, the mixture was centrifuged and washed with deionized water until neutral, then vacuum dried at 80℃ for 10h, cooled and ground to obtain layered Fe2TiO5.

[0032] Example 7 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S701: Weigh Na2CO3 and TiO2 in a mass ratio of 1:5, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 800°C for 10 h. After cooling, grind to obtain the precursor Na2TiO3.

[0033] S702: 12g of the precursor Na2TiO3 was placed in 300mL of 5mol / L Al(NO3)3 solution and stirred for 10 days. After stirring, the mixed solution was centrifuged and washed with deionized water until neutral, then vacuum dried at 100℃ for 10h, and ground after cooling to obtain layered Al2TiO5.

[0034] Example 8 The present invention provides a layered catalyst, and the preparation method of the layered catalyst includes: S801: Weigh Na2CO3 and TiO2 in a mass ratio of 1:5, mix and grind the weighed Na2CO3 and TiO2, and place them in a corundum crucible. Calcine them in a muffle furnace at 1200°C for 10 h. After cooling, grind to obtain the precursor Na2TiO3.

[0035] S802: 12g of the precursor Na2TiO3 was placed in 300mL of a 10mol / L Zn(NO3)2 solution and stirred for 10 days. After stirring, the mixture was centrifuged and washed with deionized water until neutral, then vacuum dried at 100℃ for 10h, and ground to obtain layered ZnTiO3 after cooling.

[0036] Comparative Example 1 Comparative Example 1 is the precursor Na2TiO3 prepared in Example 1.

[0037] The catalysts prepared in Examples 1 to 4 and Comparative Example 1 were tested by SEM to obtain Figure 1-5 . Figure 1-5 It can be seen that the catalysts prepared in Examples 1-4 all have a layered structure, while the catalyst prepared in Comparative Example 1 is granular and has an uneven particle size.

[0038] The catalysts prepared in Examples 1 to 4 and Comparative Example 1 of the present application were evaluated for catalytic activity, and the evaluation results shown in Table 1 were obtained. The catalyst activity evaluation method was a commonly used method in the technical field.

[0039] Table 1: Catalytic activities of the catalysts prepared in Examples 1-4 and Comparative Example 1 As can be seen from Table 1, the yield of the layered catalysts prepared in Examples 1-4 when catalyzing cyclohexene to prepare cyclohexanol reached about 14%, which is much greater than the yield of Comparative Example 1. This shows that the layered catalysts provided in the examples of the present application can significantly improve the catalytic efficiency of cyclohexene hydration.

[0040] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A layered catalyst, characterized in that The layered catalyst is layered H2TiO3 or layered M2TiO3, wherein M includes one or more of Al, Fe, Zn and Nb.

2. A method for preparing a layered catalyst, characterized in that: include: After Na2CO3 and TiO2 are mixed and ground evenly, they are calcined at a temperature of 800-1200°C for 10 hours, and then ground after cooling to obtain the precursor Na2TiO3; The precursor Na2TiO3 is placed in an acidic aqueous solution or a salt solution, stirred for 10 days, centrifuged, washed to neutrality, vacuum dried at 60-100°C for 10 hours, and ground after cooling to obtain layered H2TiO3 or M2TiO3, wherein M includes one or more of Al, Fe, Zn and Nb.

3. The method for preparing a layered catalyst according to claim 2, characterized in that: The mass ratio of Na2CO3 and TiO2 is 1:2-1:

5.

4. The method for preparing a layered catalyst according to claim 2, characterized in that: The acidic aqueous solution includes HNO3 or HCl.

5. The method for preparing a layered catalyst according to claim 2, characterized in that: The salt solution includes a nitric acid solution or a hydrochloric acid solution of Al, Fe, Zn or Nb.

6. The method for preparing a layered catalyst according to claim 2, characterized in that: The concentration of the acidic aqueous solution or the salt solution is 5-10 mol / L.

7. The method for preparing a layered catalyst according to claim 2, characterized in that: The mass volume ratio of the precursor Na2TiO3 to the acidic aqueous solution is 5-12g:300 mL.

8. The method for preparing a layered catalyst according to claim 2, characterized in that: The mass volume ratio of the precursor Na2TiO3 to the salt solution is 5-12g:300 mL.

9. The layered catalyst according to claim 1 or the layered catalyst prepared by the method according to any one of claims 2 to 8 is used for catalyzing cyclohexene to prepare cyclohexanol.

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