A catalyst for the preparation of ortho-methylated products of phenol and its application

Abstract

This invention relates to a catalyst for preparing ortho-methylated products of phenol. The catalyst is a composite oxide containing indium oxide, with the composition In₂O₃ / X, where X is a promoter. The promoter is selected from one or more of ZrO₂, HfO₂, ZnO, Cr₂O₃, CeO₂, and MgO, and the amount of the promoter metal is 0.01 to 100 times the molar amount of indium. This invention also discloses the application of this catalyst in the reaction of carbon dioxide hydrogenation coupled with phenol methylation to prepare o-cresol and 2,6-dimethylphenol. Compared with traditional catalytic methods, the catalyst of this invention has low energy consumption, long service life, and can highly selectively convert phenol to o-cresol and 2,6-dimethylphenol with almost no byproduct formation.

Description

Technical Field

[0001] This invention relates to the field of synthesis technology of o-cresol and 2,6-dimethylphenol, and more particularly to a catalyst for preparing ortho-methylated products of phenol and its application. Background Technology

[0002] o-Cresol and 2,6-Dimethylphenol, the ortho-methylated products of phenol, are very important organic intermediates. o-Cresol is mainly used to synthesize phenolic resins, pesticides, pharmaceuticals, dyes, fragrances and antioxidants, while 2,6-Dimethylphenol is mainly used to synthesize polyphenylene ether engineering plastics. Both have very broad industrial application prospects.

[0003] Currently, the vapor-phase alkylation of phenol with methanol is the main method for preparing o-cresol and 2,6-dimethylphenol, and the catalysts used are mainly magnesium-based and iron-based catalysts. However, this process requires a high reaction temperature, inevitably triggering side reactions of methanol, resulting in low methanol utilization and increased process costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a catalyst with significant effect for the preparation of ortho-methylated products of phenol.

[0005] Another technical problem to be solved by the present invention is to provide the application of the catalyst for preparing the ortho-methylated product of phenol.

[0006] To address the aforementioned problems, the present invention provides a catalyst for preparing ortho-methylated products of phenol, characterized in that: the catalyst is a composite oxide containing indium oxide, with the composition In2O3 / X, wherein X is an auxiliary agent; the auxiliary agent is selected from one or more of ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO, and the amount of the auxiliary metal is 0.01 to 100 times the molar amount of indium.

[0007] The method for preparing a catalyst for preparing ortho-methylated products of phenol as described above is characterized in that: the method refers to preparing the catalyst by using a metal precursor and / or metal oxide as raw materials and employing any one of the following methods: co-precipitation, impregnation, or deposition precipitation.

[0008] The metal precursor refers to an In salt and / or one or more auxiliary salts selected from Zr, Hf, Zn, Cr, Ce, and Mg, wherein the salt is one or more of nitrates, oxynitrates, acetates, halides, and sulfates.

[0009] The metal oxide refers to one or more oxides selected from ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO.

[0010] The application of the catalyst for preparing ortho-methylated products of phenol as described above is characterized in that: the catalyst is used in the reaction of carbon dioxide hydrogenation coupled with phenol methylation to prepare ortho-cresol and 2,6-dimethylphenol.

[0011] The o-cresol and 2,6-dimethylphenol were prepared by the following method: S1 Place 0.1 g of quartz wool in the middle of the quartz tube, fill 0.5 g of quartz sand on top of the quartz wool as the lower part of the catalyst bed, then evenly fill 0.25 g of catalyst and mix with 1.75 g of quartz sand above the lower part of the catalyst bed as the middle part of the catalyst bed, and finally fill 0.5 g of quartz sand above the middle part of the catalyst bed as the upper part of the catalyst bed, thus completing the filling of the catalyst bed of the fixed bed reactor; S2 uses phenol, carbon dioxide, and hydrogen as starting materials and employs a fixed-bed continuous flow reactor to carry out the ortho-methylation reaction of phenol. The reaction products are condensed in a condenser and the liquid products are collected.

[0012] The particle size of the quartz sand in step S1 is 40~80 mesh.

[0013] The conditions for the ortho-methylation reaction of phenol in step S2 are as follows: reaction temperature 300-450 °C, reaction pressure 0.1-9 MPa, CO2 to H2 molar ratio 1:(1-5), and gas hourly space velocity 8000-60000 mL·g. −1 ·h −1 The mass hourly space velocity (HHSV) of phenol is 0.1–6 h⁻¹. −1 .

[0014] Compared with the prior art, the present invention has the following advantages: 1. The catalyst described in this invention successfully achieves efficient generation of the active intermediate for carbon dioxide hydrogenation and further ortho-methylation of phenol during the carbon dioxide hydrogenation coupled with phenol methylation to prepare o-cresol and 2,6-dimethylphenol. The overall selectivity of the ortho-methylation products (o-cresol and 2,6-dimethylphenol) reaches 99%. Furthermore, by adjusting the reaction conditions, the product distribution can be flexibly controlled, achieving a shift from high selectivity for o-cresol to high selectivity for 2,6-dimethylphenol.

[0015] 2. The carbon dioxide hydrogenation coupled phenol methylation process of the present invention uses phenol, carbon dioxide and hydrogen as starting materials, avoiding methanol decomposition and reforming side reactions in the phenol-methanol gas phase methylation process, thus reducing production costs.

[0016] 3. Using the catalyst described in this invention, phenol can be converted into o-cresol and 2,6-dimethylphenol with high selectivity and almost no byproducts are generated.

[0017] 4. Compared with traditional catalytic methods, the catalyst described in this invention has low energy consumption and long service life, bringing huge economic and environmental benefits to industrial production. Detailed Implementation

[0018] A catalyst for preparing ortho-methylated products of phenol, the catalyst being a composite oxide containing indium oxide with the composition In2O3 / X, wherein X is an auxiliary agent; the auxiliary agent is selected from one or more of ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO, and the amount of the auxiliary metal is 0.01 to 100 times the molar amount of indium.

[0019] The preparation method refers to the following: using metal precursors and / or metal oxides as raw materials, the catalyst is prepared by any one of the following methods: co-precipitation, impregnation, or deposition-precipitation. The metal precursor refers to In salt and / or one or more auxiliary salts selected from Zr, Hf, Zn, Cr, Ce, and Mg, wherein the salt is one or more of nitrates, oxynitrates, acetates, halides, and sulfates. The metal oxide refers to one or more oxides selected from ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO.

[0020] [Preparation by co-precipitation method] The metal precursor is prepared into a solution according to a certain ratio, and then co-precipitated using a precipitant to achieve the desired result. The specific method is as follows: First, prepare an aqueous solution of the metal precursor with a concentration of 0.01–2 mol / L, and an aqueous solution of the precipitant with a concentration of 0.1–3 mol / L. The metal precursor in the aqueous solution refers to an In salt and one or more auxiliary salts selected from Zr, Hf, Zn, Cr, Ce, and Mg, wherein the molar ratio of indium to the auxiliary metal is 1:(0.01–100). The salt is one or more of nitrates, oxynitrates, acetates, halides, and sulfates. The precipitant in the aqueous solution is one or more of ammonia, ammonium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0021] Next, the aqueous solution of the metal precursor was stirred at a rate of 600 r / min in an oil bath at 60~80 ℃, while the aqueous solution of the precipitant was added dropwise until the pH of the solution was 8~10. After the addition was completed, stirring was stopped to obtain the precipitate mother liquor.

[0022] Finally, the mother liquor was aged at 60-80 °C for 12 h, then filtered to obtain the precipitate and washed with deionized water; the precipitate was first dried at 80-110 °C for 12 h, and then calcined in air at 300-500 °C for 2-6 h to obtain the In2O3 / X catalyst.

[0023] [Preparation by impregnation method] The metal precursor and metal oxide additive are thoroughly mixed in solution, and the metal element is directly deposited onto the metal oxide additive by rotary evaporation. The specific method is as follows: First, the metal oxide additive is mixed with water at a ratio of 1 g: (10~100) mL and stirred to obtain mixture A. The metal oxide additive is one or more oxides selected from ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO.

[0024] Then, the metal precursor is added to mixture A at a molar ratio of 1:(0.01~100) to obtain mixture B. The metal precursor refers to In salt and one or more auxiliary salts selected from Zr, Hf, Zn, Cr, Ce, and Mg, wherein the molar ratio of indium to auxiliary metal is 1:(0.01~100), and the salt is one or more of nitrates, oxynitrates, acetates, halides, and sulfates.

[0025] Finally, mixture B was stirred at 600 r / min for 6 h at room temperature, and after being dehydrated by rotary evaporation, it was dried at 80~110 ℃ for 12 h, and then calcined in air at 300~500 ℃ for 2~6 h to obtain the In2O3 / X catalyst.

[0026] [Prepared by sedimentation and precipitation method] A suspension is formed by mixing an aqueous solution of a metal precursor with a metal oxide auxiliary agent, and the metal element is precipitated by controlling the pH. The specific method is as follows: First, prepare an aqueous solution of the metal precursor with a concentration of 0.01–2 mol / L, and an aqueous solution of the precipitant with a concentration of 0.1–3 mol / L. The metal precursor in the aqueous solution refers to an In salt and one or more auxiliary salts selected from Zr, Hf, Zn, Cr, Ce, and Mg, wherein the molar ratio of indium to the auxiliary metal is 1:(0.01–100). The salt is one or more of nitrates, oxynitrates, acetates, halides, and sulfates. The precipitant in the aqueous solution is one or more of ammonia, ammonium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0027] Then, the metal oxide auxiliary agent is added to the aqueous solution of the metal precursor at a molar ratio of 1:(0.01~100) to obtain mixture A. The metal oxide auxiliary agent is one or more oxides selected from ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO.

[0028] Next, mix A is stirred in an oil bath at 600 r / min at 60~80 ℃, and an aqueous solution of precipitant is added dropwise until the pH of the solution is 8~10. After the addition is complete, stirring is stopped to obtain the precipitate mother liquor.

[0029] Finally, the mother liquor was aged at 60-80 °C for 12 h, then filtered to obtain the precipitate and washed with deionized water; the precipitate was first dried at 80-110 °C for 12 h, and then calcined in air at 300-500 °C for 2-6 h to obtain the In2O3 / X catalyst.

[0030] Application of a catalyst for the preparation of ortho-methylated products of phenol, wherein the catalyst is used in the carbon dioxide hydrogenation coupled with phenol methylation to prepare o-cresol and 2,6-dimethylphenol. The specific process is as follows: S1. Place 0.1 g of quartz wool in the middle of the quartz tube. Then, fill 0.5 g of quartz sand above the quartz wool to form the lower part of the catalyst bed. Next, evenly fill 0.25 g of catalyst and mix it with 1.75 g of quartz sand above the lower part of the catalyst bed to form the middle part of the catalyst bed. Finally, fill 0.5 g of quartz sand above the middle part of the catalyst bed to form the upper part of the catalyst bed, thus completing the loading of the catalyst bed in the fixed-bed reactor. The particle size of the quartz sand is 40-80 mesh.

[0031] S2 uses phenol, carbon dioxide, and hydrogen as starting materials and employs a fixed-bed continuous flow reactor for the ortho-methylation of phenol. The reaction temperature is 300–450 °C, the reaction pressure is 0.1–9 MPa, the molar ratio of CO2 to H2 is 1:(1–5), and the gas hourly space velocity is 8000–60000 mL·g. −1 ·h −1 The mass hourly space velocity (HHSV) of phenol is 0.1–6 h⁻¹. −1 The reaction products are condensed in a condenser, and the liquid products are collected.

[0032] Example 1 [Coprecipitation Method] Weigh 21.05 g In(NO3)3·4H2O and 12.88 g Zr(NO3)4·5H2O to prepare a 1000 mL aqueous solution of the metal precursor, and place it in a 3000 mL round-bottom flask. Dissolve 19.20 g (NH4)2CO3 in 1000 mL of water to obtain an aqueous solution of the precipitant. The aqueous solution of the metal precursor was placed in an oil bath at 70 °C with a stirring speed of 600 r / min. Then, the aqueous solution of the precipitant was added dropwise to the aqueous solution of the metal precursor at a rate of about 1-2 drops / s until the pH of the solution reached 8. Stirring was then stopped, and the resulting precipitate was aged in an oil bath at 70 °C for 12 h. After cooling, the solution was filtered. The precipitate was then transferred to a 2000 mL beaker and washed with deionized water with stirring for 30 min. The filtration and washing steps were repeated 3 times. The final precipitate was dried in an oven at 110 °C for 12 h. The dried precipitate was then placed in a crucible and calcined in air at 500 °C for 3 h to obtain the catalyst.

[0033] The catalyst obtained in Example 1 was tableted at 30 MPa, crushed, and sieved to obtain catalyst particles of 40-80 mesh for evaluation. Then, 0.25 g of the sieved catalyst was weighed and placed in a quartz reaction tube with an inner diameter of 10 mm. The reaction was carried out at 400 °C, 3 MPa, CO2:H2 = 1:3 (molar ratio), and gas hourly space velocity (GHSV) of 24000 mL·g⁻¹. −1 ·h −1 The mass hourly space velocity (HHSV) of phenol is 1.7 h⁻¹. −1 The reactivity was evaluated under the following conditions. After the reaction product was condensed in a condenser, the liquid product was collected. Samples were taken and analyzed every 4 hours. Qualitative analysis was performed using GC-MS, and quantitative analysis was performed using an Agilent GC-8890.

[0034] Example 2 Weigh 24.06 g In(NO3)3·4H2O and 6.4 g HfCl4 to prepare a 1000 mL aqueous solution and place it in a 3000 mL round-bottom flask. The remaining process steps, parameters and catalyst evaluation methods are the same as in Example 1.

[0035] Example 3 Weigh 21.05 g In(NO3)3·4H2O and 8.92 g Zn(NO3)2·6H2O to prepare a 1000 mL aqueous solution and place it in a 3000 mL round-bottom flask. The remaining process steps, parameters and catalyst evaluation methods are the same as in Example 1.

[0036] Example 4 Weigh 21.05 g In(NO3)3·4H2O and 12.00 g Cr(NO3)3·9H2O to prepare a 1000 mL aqueous solution and place it in a 3000 mL round-bottom flask. The remaining process steps, parameters and catalyst evaluation methods are the same as in Example 1.

[0037] Example 5 Weigh 21.05 g In(NO3)3·4H2O and 13.03 g Ce(NO3)4·6H2O to prepare a 1000 mL aqueous solution and place it in a 3000 mL round-bottom flask. The remaining process steps, parameters and catalyst evaluation methods are the same as in Example 1.

[0038] Example 6 Weigh 21.05 g In(NO3)3·4H2O and 7.69 g Mg(NO3)2·6H2O to prepare a 1000 mL aqueous solution and place it in a 3000 mL round-bottom flask. The remaining process steps, parameters and catalyst evaluation methods are the same as in Example 1.

[0039] Example 7 [Immersion Method] 10 g of ZrO2 powder and 57 g of In(NO3)3·4H2O were added to a round-bottom flask containing 500 mL of water. The resulting mixture was stirred at 600 r / min for 6 h at room temperature. After removing water by rotary evaporation, the resulting solid was dried at 80–110 °C for 12 h and then calcined at 500 °C for 3 h in air to obtain the catalyst. The evaluation method for this catalyst is the same as in Example 1.

[0040] Example 8 [Sedimentation and Precipitation Method] Dissolve 19.20 g of (NH4)2CO3 in 1000 mL of water to obtain an aqueous solution of the precipitant.

[0041] 30.08 g of In(NO3)3·4H2O and 12.32 g of ZrO2 powder were added to a round-bottom flask containing 1000 mL of water to obtain a suspension. The suspension was placed in an oil bath at 70 °C and stirred at 600 r / min. An aqueous solution of the precipitant was added dropwise to the suspension at a rate of approximately 1-2 drops / s until the pH of the solution reached 8, at which point stirring was stopped. The resulting mother liquor was aged in an oil bath at 70 °C for 12 h. After cooling, it was filtered. The precipitate was then transferred to a 2000 mL beaker and washed with deionized water with stirring for 30 min. The filtration and washing steps were repeated three times. The final precipitate was dried in an oven at 110 °C for 12 h. The dried precipitate was then calcined in air at 500 °C for 3 h in a crucible to obtain the catalyst. The remaining process steps, parameters, and catalyst evaluation methods were the same as in Example 1.

[0042] Example 9 Same as Example 1, except that: gas space velocity = 12000 mL·g −1 ·h −1 The mass hourly space velocity (HHSV) of phenol is 5.1 h⁻¹. −1 .

[0043] Example 10 Same as Example 1, except that: gas space velocity = 48000 mL·g −1 ·h −1 The mass hourly space velocity (HHSV) of phenol is 0.1 h⁻¹. −1 .

[0044] Example 11 The catalyst prepared in Example 1 was selected for stability testing. A fixed-bed reactor was used for continuous feeding and reaction. Samples of the reaction solution were collected at 4-8 h intervals for analysis. Samples were taken for analysis after 500 h of continuous operation. The results showed that the phenol conversion rate was 97%, and the total selectivity for o-cresol and 2,6-dimethylphenol was 99%. This demonstrates that the catalyst still exhibits good stability after 500 h of continuous reaction.

[0045] The phenol conversion rates and selectivity of o-cresol and 2,6-dimethylphenol in Examples 1-11 of this invention are shown in Table 1: Table 1 Conversion Rate and Selectivity Results As shown in Table 1, the catalysts of Examples 1-11 of this invention exhibit good performance in the carbon dioxide hydrogenation coupled with phenol methylation to prepare o-cresol and 2,6-dimethylphenol, with a total selectivity of 99% for the o-methylated products (o-cresol and 2,6-dimethylphenol). Furthermore, by adjusting the reaction conditions, the product distribution can be flexibly controlled, achieving a shift from high o-cresol selectivity to high 2,6-dimethylphenol selectivity.

Claims

1. A catalyst for preparing ortho-methylated products of phenol, characterized in that: The catalyst is a composite oxide containing indium oxide, with the composition In2O3 / X, where X is an additive; the additive is selected from one or more of ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO, and the amount of additive metal is 0.01 to 100 times the molar amount of indium.

2. The method for preparing a catalyst for preparing ortho-methylated products of phenol as described in claim 1, characterized in that: This method refers to preparing a catalyst using metal precursors and / or metal oxides as raw materials, employing any one of the following methods: co-precipitation, impregnation, or deposition precipitation.

3. The method for preparing a catalyst for preparing ortho-methylated products of phenol as described in claim 2, characterized in that: The metal precursor refers to an In salt and / or one or more auxiliary salts selected from Zr, Hf, Zn, Cr, Ce, and Mg, wherein the salt is one or more of nitrates, oxynitrates, acetates, halides, and sulfates.

4. The method for preparing a catalyst for preparing ortho-methylated products of phenol as described in claim 2, characterized in that: The metal oxide refers to one or more oxides selected from ZrO2, HfO2, ZnO, Cr2O3, CeO2, and MgO.

5. The application of the catalyst as described in claim 1 for preparing ortho-methylated products of phenol, characterized in that: This catalyst is used in the reaction of carbon dioxide hydrogenation coupled with phenol methylation to prepare o-cresol and 2,6-dimethylphenol.

6. The application of the catalyst as described in claim 5 for preparing ortho-methylated products of phenol, characterized in that: The o-cresol and 2,6-dimethylphenol were prepared by the following method: S1 Place 0.1 g of quartz wool in the middle of the quartz tube, fill 0.5 g of quartz sand on top of the quartz wool as the lower part of the catalyst bed, then evenly fill 0.25 g of catalyst and mix with 1.75 g of quartz sand above the lower part of the catalyst bed as the middle part of the catalyst bed, and finally fill 0.5 g of quartz sand above the middle part of the catalyst bed as the upper part of the catalyst bed, thus completing the filling of the catalyst bed of the fixed bed reactor; S2 uses phenol, carbon dioxide, and hydrogen as starting materials and employs a fixed-bed continuous flow reactor to carry out the ortho-methylation reaction of phenol. The reaction products are condensed in a condenser and the liquid products are collected.

7. The application of the catalyst as described in claim 6 for preparing ortho-methylated products of phenol, characterized in that: The particle size of the quartz sand in step S1 is 40~80 mesh.

8. The application of the catalyst as described in claim 6 for preparing ortho-methylated products of phenol, characterized in that: The conditions for the ortho-methylation reaction of phenol in step S2 are as follows: reaction temperature 300-450 °C, reaction pressure 0.1-9 MPa, CO2 to H2 molar ratio 1:(1-5), and gas hourly space velocity 8000-60000 mL·g. −1 ·h −1 The mass hourly space velocity (HHSV) of phenol is 0.1–6 h⁻¹. −1 .

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