M / ZrO2-In2O3 monatomic catalyst as well as preparation method and application thereof

Abstract

The invention discloses an M / ZrO2-In2O3 catalyst and a preparation method and application thereof.The M is obtained by loading M monoatoms on ZrO2-In2O3, M is selected from one of Pt, Pd, Ru, Rh, Ir, Au, Re and Ag, the loading capacity is 0.01 wt%-2 wt%, and the molar ratio of ZrO2 to In2O3 is (0.3-1.5): 1; the preparation method comprises the following steps: precipitating Zr salt and In salt by using alkali to obtain a metal composite hydroxide, calcining the metal composite hydroxide to obtain ZrO2-In2O3, impregnating and loading M salt on ZrO2-In2O3, and finally reducing by using low-temperature hydrogen to obtain the ZrO2-In2O3 / M-M composite photocatalyst. According to the invention, M / ZrO2-In2O3 is taken as a catalyst, the phenolic compound and CO2 are taken as raw materials, and the 2, 6-dimethylphenol or 2, 4, 6-trimethylphenol chemical is obtained with high yield through series hydrogenation and alkylation reaction of CO2.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic technology, and particularly relates to an M / ZrO 2 -In 2 O 3 single-atom catalyst, its preparation method and application. Background Art

[0002] 2,6-Dimethylphenol is an important organic chemical raw material and an intermediate in fine chemicals. It is mainly used as a monomer for engineering plastics polyphenylene ether and modified polyphenylene ether, and can also be used in the production of high-temperature epoxy resins, pesticide 2,6-dimethylaniline, and antiarrhythmic drugs in medicine. Currently, it is a net import product in China, with large market demand and high price. The literature [Chemical Engineering Science & Technology, 2021, 29, 86] reports that the methods for 2,6-dimethylphenol include natural separation method, xylene oxidation, aniline diazotization hydrolysis method, toluene chlorination hydrolysis method, and phenol alkylation method. In industrial large-scale production, the phenol alkylation method is usually mainly used for one-step synthesis, that is, using the bulk chemical products phenol and methanol with guaranteed supply as raw materials, and carrying out methylation reaction under the action of a catalyst, without generating secondary pollution and with simple post-treatment, which is more in line with the requirements of green chemistry, and the product has a very large value-added space, but it needs to be carried out at high temperature and will produce a large proportion of para-product, seriously affecting the quality. Therefore, many scientific researchers are committed to the development and research of its core key technology - the catalyst.

[0003] Currently, the catalysts used for the preparation of 2,6-dimethylphenol by the phenol alkylation method mainly include: the magnesium oxide-based catalyst of General Motors abroad, and the V 2 O 5 -Fe 2 O 3 type catalysts of Asahi Kasei Corporation, Mitsui Toatsu Chemicals, Inc., British Cnode Synthetic Chemistry Company, and URBK Company, etc. [US4201880; US4227024; US4554267]. Domestically, there are manganese oxide composite oxide catalysts developed by Hunan Research Institute of Chemical Industry [Petrochemical Technology, 1996, 4, 253], MgO series catalysts developed by Beijing Research Institute of Chemical Industry and Shanghai Institute of Synthetic Resins [Petrochemical Technology, 1997, 26, 282], and Fe-based composite catalysts prepared by Hunan Changling Petrochemical Science & Technology Development Co., Ltd. by the co-precipitation method [CN 103084213 A]. In addition, US4429171 and CN1634656A respectively disclose catalysts composed of five elements of Fe, In, Cr, Si, K and seven elements of Fe, In, Cr, Si, Ca, K, C, and their activities are significantly improved, the highest phenol conversion rate can reach 100%, and the selectivity of 2,6-dimethylphenol reaches more than 97%. However, the catalyst components are many and the preparation is complex, resulting in poor reproducibility and it is not easy to obtain catalyst products with stable performance.

[0004] In the technology of preparing 2,6-dimethylphenol by phenol alkylation, methanol, one of the raw materials, can be alkylated by CO 2 It is prepared by hydrogenation of CO 2 Hydrogenation and alkylation of aromatic rings to produce high-value chemicals, such as patent [CN115646536A] discloses a metal oxide-molecular sieve composite catalyst for CO 2 Methylation of aromatics to produce p-xylene, i.e. CO 2 The methoxy intermediate species is generated by hydrogenation on the metal compound, and then quickly migrates to the acidic site of the molecular sieve to react with benzene / toluene to produce p-xylene with high selectivity. x The solid solution is hydrogenated to generate methoxy intermediates which diffuse to ZSM-5 to undergo electrophilic substitution with toluene to generate xylene. Compared with the direct use of methanol as an alkylating agent, its selectivity is increased by 1.5 times. 2 The catalyst must have the following functions: ① no phenol hydroxyl removal and benzene ring hydrogenation saturation activity; ② to make CO 2 Hydrogenation stays at the methoxy intermediate; ③ Weak hydrogen activation ability. Summary of the invention

[0005] In view of the technical requirements of the above catalyst, the present invention aims to provide a M / ZrO 2 -In 2 O 3 Catalyst and its preparation method and application, based on M / ZrO 2 -In 2 O 3 As catalysts, phenolic compounds (such as phenol, guaiacol, 2,6-dimethoxyphenol, p-methylphenol, 4-methylguaiacol, 2,6-dimethoxy-4-methylphenol) and CO 2 As raw material, through CO 2 The tandem hydrogenation and alkylation reactions can yield 2,6-dimethylphenol or 2,4,6-trimethylphenol chemicals in high yield.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A M / ZrO 2 -In 2 O 3 Single atom catalyst, composed of M single atoms supported on ZrO 2 -In 2 O 3obtained above, wherein M is selected from one of Pt, Pd, Ru, Rh, Ir, Au, Re and Ag, the loading amount is 0.01 wt% to 2 wt%, and ZrO 2 / In 2 O 3 The molar ratio is 0.3 to 1.5:1.

[0008] The present invention also provides the above-mentioned M / ZrO 2 -In 2 O 3 The preparation method of the single-atom catalyst is as follows: first, a metal composite hydroxide is precipitated from a Zr salt and an In salt by using an alkali, and then the metal composite hydroxide is calcined to obtain ZrO 2 -In 2 O 3 Then, the M salt is impregnated and loaded on ZrO 2 -In 2 O 3 Finally, it is reduced by low-temperature hydrogen to obtain M / ZrO 2 -In 2 O 3 Single-atom catalyst.

[0009] Furthermore, the alkali is one or more of NaOH, KOH, NaHCO 3 , NH 3 ·H 2 O, and the M salt, Zr salt and In salt are all their nitrates, acetates, chlorides, phosphates or sulfates.

[0010] Furthermore, the calcination temperature is 300 to 600 °C, and the calcination time is 1 to 10 h.

[0011] Furthermore, the temperature of low-temperature hydrogen reduction is 50 to 300 °C, and the reduction time is 0.5 to 10 h.

[0012] The present invention also provides the application of the above-mentioned M / ZrO 2 -In 2 O 3 Single-atom catalyst. Using phenolic compounds, CO 2 and H 2 as raw materials, and using M / ZrO 2 -In 2 O 3 as a catalyst, hydrogenate CO 2 and alkylate phenolic compounds to obtain 2,6-dimethylphenol or 2,4,6-trimethylphenol chemical products; the phenolic compounds are phenol, guaiacol, 2,6-dimethoxyphenol, p-cresol, 4-methylguaiacol or 2,6-dimethoxy-4-methylphenol.

[0013] The beneficial effects of the present invention are:

[0014] The M / ZrO 2 -In 2 O 3 The single-atom catalyst has good catalytic activity and can convert CO 2 Phenolic compounds (such as phenol, guaiacol, 2,6-dimethoxyphenol, p-methylphenol, 4-methylguaiacol, 2,6-dimethoxy-4-methylphenol) are hydrogenated and alkylated to synthesize 2,6-dimethylphenol or 2,4,6-trimethylphenol chemicals, the conversion rate of phenolic compounds reaches 100%, the yield of the product is not less than 99%, and the product has excellent reusability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the HAADF-STEM image of the catalyst obtained in Example 1;

[0016] like Figure 1 As shown, the white bright spot is single-atom Pt, and no Pt nanoparticles are observed, indicating that the prepared catalyst is a single-atom dispersed catalyst. DETAILED DESCRIPTION

[0017] For a clearer description, the present invention is further described below in conjunction with the embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0018] Example 1

[0019] Press ZrO 2 / In 2 O 3 The molar ratio is 1.0, weigh 1.8g Zr(NO 3 ) 2 ·5H 2 O, 1.3 g In(NO 3 ) 3 9H 2 O was dissolved in 20 mL of distilled water, and 2.0 g of NaOH was dissolved in 50 mL of deionized water. Both were dripped into the reaction vessel at the same time and stirred vigorously. The reaction temperature was 30 °C. After the reaction was completed, the precipitate was filtered, separated, dried, and calcined at 500 °C for 4 h to obtain ZrO 2 -In 2 O 3 The carrier is prepared with 15 ml of chloroplatinic acid aqueous solution according to the Pt loading amount of 0.01 wt.%, and then the carrier is dispersed in the chloroplatinic acid aqueous solution, immersed at 30°C for 1 hour and then dried, and finally reduced at 50°C in a hydrogen atmosphere for 1 hour to obtain the catalyst.

[0020] Add 15 g of n - tridecane, 0.4 g of phenol, and 0.1 g of the above catalyst into a high - pressure reactor. Use the displacement method to remove the air in the reactor, and then introduce CO 2 and H 2 , H 2 / CO 2 with a volume ratio of 3 and a total pressure of 4 MPa. Then, heat up to 250 °C, adjust the rotation speed to 900 rpm / min. After the reaction lasts for 15 h, the conversion rate of phenol is 100%, and the selectivity of 2,6 - dimethylphenol is greater than 99%. After 6 cycles of the reaction, the activity of the catalyst remains basically unchanged.

[0021] Example 2

[0022] Weigh 3.2 g of Zr(NO 2 / In 2 O 3 in a molar ratio of 1.5, and 1.5 g of In(NO 3 ) 2 ·5H 2 O, 1.5 g of In(NO 3 ) 3 ·9H 2 O and dissolve them in 20 mL of distilled water. Separately, dissolve 2.0 g of KOH in 50 mL of deionized water. Then, drop both solutions into the reaction vessel simultaneously and stir vigorously. The reaction temperature is 80 °C. After the reaction ends, filter and separate the precipitate, dry it, and calcine it at 600 °C for 1 h to obtain the ZrO 2 -In 2 O 3 support. Prepare 15 ml of palladium chloride acetone solution with a Pd loading of 0.05 wt.%. Then, disperse the support in the palladium chloride acetone solution, impregnate it at 80 °C for 48 h, and then dry it. Finally, reduce it in a hydrogen atmosphere at 100 °C for 0.5 h to obtain the catalyst.

[0023] Add 15 g of n - tridecane, 0.4 g of 4 - methylphenol, and 0.1 g of the above catalyst into a high - pressure reactor. Use the displacement method to remove the air in the reactor, and then introduce CO 2 and H 2 , H 2 / CO 2 with a volume ratio of 3 and a total pressure of 4 MPa. Then, heat up to 250 °C, adjust the rotation speed to 900 rpm / min. After the reaction lasts for 15 h, the conversion rate of 4 - methylphenol is 100%, and the selectivity of 2,4,6 - trimethylphenol is greater than 99%. After 6 cycles of the reaction, the activity of the catalyst remains basically unchanged.

[0024] Example 3

[0025] According to ZrO 2 / In 2 O3 Weigh 0.6 g of Zr(NO 3 ) 2 ·5H 2 O and 1.5 g of In(NO 3 ) 3 ·9H 2 O and dissolve them in 20 mL of distilled water. Then, simultaneously drip the above solution and ammonia water into the reaction vessel and stir vigorously. The reaction temperature is 10 °C. After the reaction is completed, filter and separate the precipitate, dry it, and calcine it at 300 °C for 5 h to obtain the ZrO 2 -In 2 O 3 support. Prepare a 15 ml ruthenium chloride methanol solution with a Ru loading of 5 wt.%. Then disperse the support in the ruthenium chloride methanol solution, impregnate it at 100 °C for 12 h and then dry it. Finally, reduce it in a hydrogen atmosphere at 300 °C for 0.5 h to obtain the catalyst.

[0026] Add 15 g of n-tridecane, 0.4 g of 4-methylphenol, and 0.1 g of the above catalyst into a high-pressure reaction kettle. Use the displacement method to remove the air in the kettle, and introduce CO 2 and H 2 , with the volume ratio of H 2 / CO 2 being 3 and the total pressure being 4 MPa. Then heat it up to 250 °C, adjust the rotation speed to 900 rpm / min. After the reaction lasts for 15 h, the conversion rate of 4-methylphenol is 100%, and the selectivity of 2,6-dimethylphenol is greater than 99%. After 6 cycles of the reaction, the activity of the catalyst remains basically unchanged.

[0027] Example 4

[0028] Weigh 3.2 g of Zr(NO 2 / In 2 O 3 with a molar ratio of 1.5. Weigh 3.2 g of Zr(NO 3 ) 2 ·5H 2 O and 1.5 g of In(NO 3 ) 3 ·9H 2 O and dissolve them in 20 mL of distilled water. Additionally, dissolve 2.0 g of NaHCO 3 in 50 mL of deionized water. Then, simultaneously drip the two into the reaction vessel and stir vigorously. The reaction temperature is 80 °C. After the reaction is completed, filter and separate the precipitate, dry it, and calcine it at 400 °C for 5 h to obtain the ZrO 2 -In 2 O 3The carrier: Prepare 15 ml of rhodium chloride ethanol solution with a Rh loading of 0.1 wt.%, then disperse the carrier in the rhodium chloride ethanol solution, let it stand at 60 °C for 12 h and then dry it, and finally reduce it in a hydrogen atmosphere at 250 °C for 3 h to obtain the catalyst.

[0029] Add 15 g of n-tridecane, 0.4 g of 2,6-dimethoxy-4-methylphenol, and 0.1 g of the above catalyst into a high-pressure reactor. Use the displacement method to remove the air in the reactor, and then introduce CO 2 and H 2 ,H 2 / CO 2 with a volume ratio of 3 and a total pressure of 4 MPa. Then heat it up to 200 °C, adjust the rotation speed to 900 rpm / min, and after reacting for 15 h, the conversion rate of 2,6-dimethoxy-4-methylphenol is 100%, and the selectivity of 2,4,6-trimethylphenol is greater than 99%. After 6 cycles of reaction, the activity of the catalyst basically remains unchanged.

[0030] Example 5

[0031] Weigh 1.28 g of Zr(NO 2 / In 2 O 3 ) 3 ) 2 ·5H 2 O and 1.3 g of In(NO 3 ) 3 ·9H 2 O according to a molar ratio of 1.0 and dissolve them in 20 mL of distilled water. Separately, dissolve 2.0 g of NaOH in 50 mL of deionized water, and then drop them into the reaction vessel simultaneously and stir vigorously. The reaction temperature is 30 °C. After the reaction, filter and separate the precipitate, dry it, and calcine it at 400 °C for 5 h to obtain the ZrO 2 -In 2 O 3 carrier. Prepare 15 ml of iridium chloride acetone solution with an Ir loading of 0.05 wt.%, then disperse the carrier in the iridium chloride acetone solution, let it stand at 60 °C for 6 h and then dry it, and finally reduce it in a hydrogen atmosphere at 250 °C for 6 h to obtain the catalyst.

[0032] Add 15 g of n-undecane, 0.4 g of 4-methylguaiacol, and 0.1 g of the above catalyst into a high-pressure reactor. Use the displacement method to remove the air in the reactor, and then introduce CO 2 and H 2 ,H 2 / CO 2The volume ratio is 2, the total pressure is 4 MPa, then the temperature is raised to 250 °C, the rotation speed is adjusted to 900 rpm / min. After the reaction lasts for 15 h, the conversion rate of 4-methylguaiacol is 100%, the selectivity of 2,4,6-trimethylphenol is greater than 99%. After 6 cycles of reaction, the activity of the catalyst remains basically unchanged.

[0033] Example 6

[0034] Weigh 1.6 g of Zr(NO 2 / In 2 O 3 according to the molar ratio of 1.2, and 1.5 g of In(NO 3 ) 2 ·5H 2 O, 1.5 g of In(NO 3 ) 3 ·9H 2 O are dissolved in 20 mL of distilled water. The above solution and ammonia water are simultaneously dropped into the reaction vessel and stirred vigorously. The reaction temperature is 30 °C. After the reaction ends, the precipitate is filtered, separated, dried, and calcined at 500 °C for 3 h to obtain the ZrO 2 -In 2 O 3 support. Prepare 15 ml of chloroauric acid acetone solution according to the Au loading of 0.25 wt.%. Then disperse the support in the chloroauric acid acetone solution, let it stand at 60 °C for 12 h and then dry it. Finally, reduce it in a hydrogen atmosphere at 50 °C for 6 h to obtain the catalyst.

[0035] Add 15 g of n-tridecane, 0.4 g of guaiacol, and 0.1 g of the above catalyst into the high-pressure reactor. Use the displacement method to remove the air in the reactor, and introduce CO 2 and H 2 . The H 2 / CO 2 volume ratio is 3, the total pressure is 4 MPa, then the temperature is raised to 250 °C, the rotation speed is adjusted to 900 rpm / min. After the reaction lasts for 15 h, the conversion rate of guaiacol is 100%, the selectivity of 2,6-dimethylphenol is greater than 99%. After 6 cycles of reaction, the activity of the catalyst remains basically unchanged.

[0036] Example 7

[0037] Weigh 1.8 g of Zr(NO 2 / In 2 O 3 according to the molar ratio of 1.0, and 1.3 g of In(NO 3 ) 2 ·5H 2 O, 1.3 g of In(NO 3 ) 3 ·9H 2O was dissolved in 20 mL of distilled water. Separately, 2.0 g of NaOH was dissolved in 50 mL of deionized water. The two were simultaneously dropped into the reaction vessel and stirred vigorously. The reaction temperature was 40 °C. After the reaction, the precipitate was filtered, separated, dried, and calcined at 600 °C for 2 h to obtain ZrO 2 -In 2 O 3 support. A 15 ml acetone solution of perrhenic acid was prepared according to a Re loading of 0.05 wt.%. Then the support was dispersed in the acetone solution of perrhenic acid, left standing at 60 °C for 12 h and then dried. Finally, it was reduced in a hydrogen atmosphere at 150 °C for 1 h to obtain the catalyst.

[0038] 15 g of n-dodecane, 0.4 g of 4-methylbenzene, and 0.1 g of the above catalyst were added to a high-pressure reactor. The air in the reactor was removed by the displacement method, and CO 2 and H 2 were introduced, and the volume ratio of H 2 / CO 2 was 3. The total pressure was 4 MPa. Then the temperature was raised to 250 °C, the rotation speed was adjusted to 900 rpm / min, and the reaction continued for 15 h. The conversion rate of 4-methylphenol was 100%, and the selectivity of 2,4,6-trimethylphenol was greater than 99%. After 6 cycles of the reaction, the activity of the catalyst remained basically unchanged.

[0039] Example 8

[0040] According to the molar ratio of ZrO 2 / In 2 O 3 of 0.8, 1.1 g of Zr(NO 3 ) 2 ·5H 2 O and 1.3 g of In(NO 3 ) 3 ·9H 2 O were dissolved in 20 mL of distilled water. Separately, 2.0 g of NaOH was dissolved in 50 mL of deionized water. The two were simultaneously dropped into the reaction vessel and stirred vigorously. The reaction temperature was 40 °C. After the reaction, the precipitate was filtered, separated, dried, and calcined at 600 °C for 2 h to obtain ZrO 2 -In 2 O 3 support. A 15 ml acetone solution of silver nitrate was prepared according to an Ag loading of 0.05 wt.%. Then the support was dispersed in the acetone solution of silver nitrate, left standing at 60 °C for 12 h and then dried. Finally, it was reduced in a hydrogen atmosphere at 150 °C for 1 h to obtain the catalyst.

[0041] 15 g of n-dodecane, 0.4 g of phenol, and 0.1 g of the above catalyst were added to a high-pressure reactor. The air in the reactor was removed by the displacement method, and CO 2 and H2 , H 2 / CO 2 The volume ratio is 3, the total pressure is 4 MPa, then the temperature is raised to 250 °C, the rotation speed is adjusted to 900 rpm / min. After the reaction lasts for 15 h, the conversion rate of phenol is 100%, and the selectivity of 2,6-dimethylphenol is greater than 99%. After 6 cycles of the reaction, the activity of the catalyst remains basically unchanged.

[0042] Comparative Example 1

[0043] Same as Example 1, the only difference is that the carrier is pure ZrO 2 , and under the same reaction conditions, Pt / ZrO 2 The conversion rate of phenol catalyzed is only 2.8%, the product is o-methylphenol, and the selectivity of 2,6-dimethylphenol is 0.

[0044] Comparative Example 2

[0045] Same as Example 1, the only difference is that the carrier is pure In 2 O 3 , and under the same reaction conditions, Pt / In 2 O 3 The conversion rate of phenol catalyzed is 70%, and the selectivity of 2,6-dimethylphenol is 14%.

[0046] Comparative Example 3

[0047] Same as Example 1, the difference is that Pt is not loaded. Under the same reaction conditions, ZrO 2 / In 2 O 3 The conversion rate of phenol catalyzed is 85.1%, and the selectivity of 2,6-dimethylphenol is 28.7%.

Claims

1. A M / ZrO2-In2O3 single-atom catalyst, characterized in that: The M / ZrO2-In2O3 single-atom catalyst is obtained by loading M single atoms on ZrO2-In2O3, wherein M is selected from one of Pt, Pd, Ru, Rh, Ir, Au, Re and Ag, the loading amount is 0.01wt% to 2wt%, and the ZrO2 / In2O3 molar ratio is 0.3 to 1.5:

1.

2. The method for preparing the M / ZrO2-In2O3 single-atom catalyst according to claim 1, characterized in that: First, Zr salt and In salt are precipitated with alkali to obtain metal composite hydroxide, and then the metal composite hydroxide is calcined to obtain ZrO2-In2O3, and then M salt is impregnated and loaded on ZrO2-In2O3, and finally low-temperature hydrogen reduction is performed to obtain M / ZrO2-In2O3 single-atom catalyst.

3. The preparation method according to claim 2, characterized in that: The base is one or more of NaOH, KOH, NaHCO3, NH3·H2O, and the M salt, Zr salt and In salt are all nitrates, acetates, chlorides, phosphates or sulfates thereof.

4. The preparation method according to claim 2, characterized in that: The calcination temperature is 300-600°C, and the calcination time is 1-10h.

5. The preparation method according to claim 2, characterized in that: The temperature of low-temperature hydrogen reduction is 50-300°C, and the reduction time is 0.5-10h.

6. Use of the M / ZrO2-In2O3 single-atom catalyst according to claim 1 or the M / ZrO2-In2O3 single-atom catalyst prepared by the preparation method according to any one of claims 2 to 5, characterized in that: With phenolic compounds, CO2 and H2 as raw materials and M / ZrO2-In2O3 as catalyst, CO2 is hydrogenated and alkylated to obtain 2,6-dimethylphenol or 2,4,6-trimethylphenol chemicals; the phenolic compounds are phenol, guaiacol, 2,6-dimethoxyphenol, p-methylphenol, 4-methylguaiacol or 2,6-dimethoxy-4-methylphenol.

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