MESOPOROUS CeO2 SUPPORTED Rh CATALYST AND PREPARATION METHOD AND APPLICATION THEREOF

Abstract

To provide a mesoporous CeO2 supported Rh catalyst and a preparation method and application thereof.SOLUTION: A preparation method comprises a step of: preparing a mesoporous CeO2 carrier material by using a hydrothermal synthesis method and then preparing a mesoporous Rh (0)-CeO2 catalyst with a high specific surface area by using an impregnation-reduction method. The mesoporous CeO2 supported Rh catalyst prepared by the preparation method is used to catalyze the hydroformylation of olefins. The preparation method provided by the invention is simple to operate and mild in condition, the obtained catalyst is good in active site dispersity. When the catalyst is used for catalyzing olefin hydroformylation to synthesize the aldehyde compound, the conversion rate of the raw material olefin is high, and the selectivity of the product aldehyde compound is good, and furthermore the product and the catalyst are easy to separate, and the catalyst can be recycled. The operation is simple, and the method is economical and environmentally friendly, and has a good application prospect.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the field of catalyst technology, in particular to mesoporous CeO2 supported Rh catalyst and its preparation method and use. [Background technology]

[0002] The hydroformylation of olefins is considered to be one of the most important and atom-economical methods for preparing aldehydes, and is one of the most important industrial catalytic technologies for producing aldehydes and related products. The hydroformylation of olefins with syngas (CO and H2) produces aliphatic aldehydes, which can be further used to prepare alcohols, acids, amines, esters and other compounds. The chemicals derived from this process are widely used in the plasticizer, detergent, solvent, pharmaceutical, polymer, cosmetics, agrochemical and food industries. Aldehydes are also widely used in the synthesis of building blocks and fine chemical intermediates in plastics and fiber production. Therefore, the hydroformylation of olefins is one of the most widely studied catalytic processes in academia and industry.

[0003] The first hydroformylation catalyst was the cobalt complex HCo(CO)4, and BASF and ICI developed first- and second-generation cobalt-based catalysts. However, the cobalt catalytic process requires harsh conditions such as high temperature and pressure (100-200°C, 10-30MPa) to obtain a sustained reaction rate and to ensure the stable presence of the catalytically active substance HCo(CO)4. This limits the large-scale industrial application of cobalt-based hydroformylation. Currently, noble metal catalysts still occupy a leading position in catalytic reactions due to their high catalytic activity. Rhodium catalysts are considered to be one of the most promising and optimal catalysts in catalyzing the hydroformylation reaction of olefins, with better activity and stability, and high activity and selectivity in catalyzing the hydroformylation reaction of olefins. Therefore, most of the conventional olefin hydroformylation reactions use rhodium catalysts modified with phosphorus ligands such as triphenylphosphine, and these catalysts have high chemical selectivity and region selectivity for olefins under relatively mild conditions. In addition, the prior art also includes research on metal oxide carrier-supported rhodium-based catalysts for the hydroformylation of olefins. For example, by adjusting the product region selectivity through reaction coupling, that is, by coupling with steam conversion reaction without adding ligands, styrene can be highly selectively converted to 3-phenylpropionaldehyde, with a normal to iso ratio as high as 3:1. However, the above technical solutions have disadvantages such as complicated preparation methods, high costs, strict catalytic reaction conditions, and inability to be reused multiple times.

[0004] Therefore, how to provide a catalyst for olefin hydroformylation reaction with low cost and high catalytic efficiency is a technical problem that must be urgently solved by those skilled in the art. Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the above technical problems, the present invention proposes a mesoporous CeO2 supported Rh catalyst and its preparation method and use. [Means for solving the problem]

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] The preparation method of mesoporous CeO2 supported Rh catalyst is as follows: The process involves preparing mesoporous CeO2 support material by hydrothermal synthesis, and then preparing high-surface-area mesoporous Rh(0)-CeO2 catalyst by impregnation-reduction.

[0008] Beneficial effect: In the alkaline hydrothermal system of ammonia water of the present invention, Ce(NO3)3·6H2O forms precipitates and transforms into mesoporous CeO2 support material with high specific surface area. It is 140m 2 / g and abundant mesoporous pores, which are advantageous for dispersing and supporting catalytic active sites.

[0009] Preferably, the process for preparing mesoporous CeO2 support material by hydrothermal synthesis comprises: The method includes a step of adding Ce(NO3)3·6H2O to diluted ammonia water, stirring and mixing the mixture, and then carrying out a hydrothermal reaction to obtain the mesoporous CeO2 support material.

[0010] The present invention uses a hydrothermal method to prepare mesoporous CeO2 support material, which has a fast reaction rate and can prepare CeO2 support material with high purity and better structural uniformity under the supercritical state, providing conditions for uniform loading of Rh.

[0011] Preferably, the diluted ammonia water is obtained by mixing concentrated ammonia water and water in a volume ratio of 13.5:108; The concentration of the concentrated aqueous ammonia is 28%.

[0012] The ratio of the added amount of concentrated ammonia water to Ce(NO3)3·6H2O was 13.5ml:0.74g.

[0013] Beneficial effects: Ce(NO3)3·6H2O in the present invention reacts with ammonia water in a hydrothermal environment and is finally transformed into mesoporous CeO2 support material with high specific surface area.

[0014] Preferably, the temperature of the hydrothermal reaction is 75° C. and the time is 24 h.

[0015] Beneficial effect: Due to the high reaction rate of the hydrothermal method, the present invention adopts low temperature to reduce the reaction rate in the preparation process of the support material to a certain extent, so that the uniformity of the prepared support material can be better.

[0016] Preferably, the process for preparing catalytic mesoporous Rh(0)-CeO2 by the impregnation-reduction method comprises: The process includes mixing the dispersion of the mesoporous CeO2 support material with a RhCl3·3H2O solution, soaking it, drying it after complete immersion, and then placing it in a mixed gas atmosphere of H2 and Ar to carry out a reduction reaction to obtain the mesoporous Rh(0)-CeO2 catalyst.

[0017] The preparation of the catalytic mesoporous Rh(0)-CeO2 by the immersion reduction method of the present invention does not require special equipment or complicated processes, can greatly reduce the preparation cost and preparation difficulty, and is simple and easy to implement. By adjusting the concentration of the catalyst precursor solution, immersion time, temperature and other parameters during the preparation process, precise control of the morphology, size and distribution of the catalyst particles can be realized. The atomic precision of the active components in the preparation process can be better controlled, and the atomic utilization rate of the catalyst can be effectively improved.

[0018] Preferably, the concentration of the dispersion of the mesoporous CeO2 support material is 10 mg / ml and the solvent is ethanol; The RhCl3·3H2O solution 3+ The concentration is 1.2 mg / ml and the solvent is ethanol.

[0019] Beneficial effects: After the RhCl3·3H2O of the present invention is dissolved in the ethanol solvent, it is favorable for diffusion and adsorption in the pores of the mesoporous CeO2 support material. Due to the volatility of ethanol, the solvent can be easily removed quickly, which can prevent the metal components from agglomerating into large particles, and thus improve the dispersion degree of the catalytically active component of Rh.

[0020] Preferably, the mesoporous CeO2 support material and Rh 3+ The mass ratio of is 100:(1-3).

[0021] Beneficial effect: The present invention is advantageous in providing many Rh catalytic active sites without causing aggregation of metal nanoparticles by controlling the mass loading amount of Rh to 1 wt% to 3 wt%.

[0022] Preferably, the reduction reaction temperature is 300° C. and the reduction reaction time is 2 hours. The volume ratio of H2 to Ar is 1:3.

[0023] Beneficial effect: Under the reducing atmosphere of the above mixed gas, Rh adsorbed in the pores of the mesoporous CeO2 support material 3+ is reduced to its elemental state and uniformly and highly dispersedly supported within the pores of the mesoporous CeO2 support material, providing a higher catalytically active specific surface area.

[0024] A mesoporous CeO2-supported Rh catalyst prepared by the method for preparing a mesoporous CeO2-supported Rh catalyst, in which the amount of Rh supported is 1 to 3 wt% and the specific surface area is 143.8 m 2 / g, with an average pore size of 6.7 nm.

[0025] Beneficial effects: The mesoporous CeO2-supported Rh catalyst prepared by the present invention has a large specific surface area, small pore size and good uniformity. The loading amount of the active component Rh is greatly improved, the number of active sites is increased, and the active component is uniformly distributed on the support, which improves the catalytic activity of the catalyst.

[0026] Use of mesoporous CeO2 supported Rh catalysts to catalyze the hydroformylation of olefins.

[0027] The process for catalyzing the hydroformylation of an olefin comprises: The process involves mixing the mesoporous Rh(0)-CeO2 catalyst with an olefin and a solvent, passing a synthesis gas at 2 MPa through the reaction system, and catalyzing the hydroformylation of olefins at 120°C to synthesize aldehyde compounds. The conversion rate of olefins is as high as 99%, and the yield of the product aldehyde is more than 95%.

[0028] the solvent is dioxane; The synthesis gas is a mixture of CO and H2 in a volume ratio of 1:1. Effect of the Invention

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] The mesoporous CeO2 support material prepared in this invention is obtained by hydrothermal synthesis method using ammonia water as a precipitant, and the mesoporous Rh(0)CeO2 catalyst is obtained by impregnation-reduction method. The specific surface area of ​​the obtained Rh(0)CeO2 catalyst is 143.8m 2 / g, and the average pore size is 6.7nm. The preparation method provided by the present invention is simple to operate, the conditions are mild, and the obtained catalytic active sites have good dispersion, and when used in catalyzing the hydroformylation of olefins to synthesize aldehyde compounds, the conversion rate of raw olefins is high, the selectivity of product aldehyde compounds is good, and the separation between the product and catalyst is easy, the catalyst can be recycled, the operation is simple, economical, environmentally friendly, and has good application prospects. [Brief description of the drawings]

[0031] The drawings constituting a part of this application are intended to provide a further understanding of the application, and the illustrative embodiments and the description thereof are intended to explain the application and are not to be construed as unduly limiting the application. [Figure 1]TEM images of the mesoporous Rh(0)-CeO2 catalyst obtained in Example 1 of the present invention. (a) is a TEM image at a 50 nm scale, (b) is a TEM image at a 20 nm scale, (c) is a TEM image at a 10 nm scale, and (d) is a TEM image and lattice diagram at a 2 nm scale. [Diagram 2] FIG. 2 is a graph showing the adsorption and desorption curves of the mesoporous CeO2 support material and the Rh(0)-CeO2 catalyst obtained in Example 1 of the present invention. [Diagram 3] 1 is a pore size distribution diagram of the mesoporous CeO2 support material and the Rh(0)-CeO2 catalyst obtained in Example 1 of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The technical aspects of the embodiments of the present invention will be described below clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, but it is clear that the described embodiments are only some of the embodiments of the present invention and are not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative labor belong to the scope of protection of the present invention.

[0033] In order to make the above-mentioned objectives, features and advantages of the present invention more clearly comprehensible, the present invention will be described in more detail below in conjunction with the drawings and specific embodiments.

[0034] The present invention provides a method for preparing mesoporous CeO2 supported Rh catalyst, First, the mesoporous CeO2 support material is prepared by hydrothermal synthesis, and then the high-surface-area mesoporous Rh(0)-CeO2 catalyst is prepared by the immersion-reduction method.

[0035] In some preferred embodiments, the process for preparing a mesoporous CeO2 support material by hydrothermal synthesis includes adding Ce(NO3)3·6H2O to diluted ammonia water, stirring and mixing, and then performing a hydrothermal reaction to obtain the mesoporous CeO2 support material.

[0036] The diluted ammonia water is obtained by mixing concentrated ammonia water and water in a volume ratio of 13.5:108, and the mass concentration of the concentrated ammonia water is 28%. The ratio of the amount of concentrated ammonia water to the amount of Ce(NO3)3·6H2O added is 13.5ml:0.74g.

[0037] In some preferred embodiments, the hydrothermal reaction is carried out at a temperature of 75° C. for a time of 24 hours.

[0038] In some preferred embodiments, the process for preparing the mesoporous Rh(0)-CeO2 catalyst by the impregnation-reduction method includes: The process includes mixing the dispersion of the mesoporous CeO2 support material with a RhCl3·3H2O solution, soaking it, drying it after complete immersion, and then placing it in a mixed gas atmosphere of H2 and Ar to carry out a reduction reaction to obtain the mesoporous Rh(0)-CeO2 catalyst.

[0039] In some preferred embodiments, the concentration of the dispersion of the mesoporous CeO2 support material is 10 mg / ml and the solvent is ethanol; The RhCl3·3H2O solution 3+ The concentration is 1.2 mg / ml and the solvent is ethanol.

[0040] Preferably, the mesoporous CeO2 support material and Rh 3+ The mass ratio of is 100:3.

[0041] Preferably, the reduction reaction temperature is 300° C. and the reduction reaction time is 2 hours. The volume ratio of H2 to Ar is 1:3.

[0042] The present invention also provides a mesoporous CeO2-supported Rh catalyst prepared by the method for preparing a mesoporous CeO2-supported Rh catalyst, in which the amount of Rh supported is 1 wt%-3 wt%.

[0043] The present invention also provides the use of a mesoporous CeO2 supported Rh catalyst for catalyzing the hydroformylation of olefins.

[0044] The present invention also provides a method for catalyzing the hydroformylation of an olefin, comprising: The process includes mixing the mesoporous Rh(0)-CeO2 catalyst with an olefin and a solvent, passing a synthesis gas at 2 MPa through the reaction system, and catalyzing the hydroformylation of the olefin at 120°C to synthesize an aldehyde compound.

[0045] In some preferred embodiments, the solvent is dioxane and the syngas is a 1:1 mix of CO and H2 by volume.

[0046] All of the raw materials used in the examples of the present invention are commercially available.

[0047] In the examples of the present invention, the olefin conversion rate and the yield of the product aldehyde are both analyzed by gas chromatography. The olefin conversion rate is calculated according to the formula (I): Conversion rate = converted olefin amount / total olefin amount × 100% (I); The yield of the product aldehyde is calculated as shown in formula (II): Yield = amount of aldehyde actually produced / theoretical mass of aldehyde product × 100% (II).

[0048] Example 1

[0049] The preparation method of mesoporous CeO2 supported Rh catalyst is as follows: (1) 13.5mL of concentrated ammonia water (28%) was weighed into a Teflon-lined hydrothermal kettle, 108mL of deionized water was added and stirred, 0.74g of Ce(NO3)3·6H2O was weighed and added to the above system, and after stirring at room temperature for 1 hour, the mixture was placed in a kettle and subjected to hydrothermal reaction at 75℃ for 24 hours. After the reaction was completed, the mixture was cooled, and the sample was taken out, suction filtered, and dried overnight to obtain a yellow mesoporous CeO2 support material powder. (2) 400 mg of the mesoporous CeO2 support material obtained in step (1) was weighed out, mixed with 40 mL of ethanol, and stirred at room temperature for 2 hours to uniformly disperse the material, thereby obtaining a mesoporous CeO2 support material dispersion. In addition, 12 mg of Rh was added to the mesoporous CeO2 support material dispersion. 3+ The process includes dissolving RhCl3·3H2O containing dimethylformamide in 10ml of ethanol, drawing up the RhCl3·3H2O solution with a 5mL syringe, adding it dropwise to the above mesoporous CeO2 support material dispersion, soaking it for 12 hours, and then placing the sample on a rotary evaporator for spin-deposition drying to obtain yellow powder Rh(III)-CeO2. The Rh(III)-CeO2 is then placed in an atmospheric mixed atmosphere of H2 and Ar in a volume ratio of 1:3, and reduced at 300℃ for 2 hours to obtain a mesoporous Rh(0)-CeO2 catalyst with a high specific surface area.

[0050] The specific surface area of ​​the obtained Rh(0)-CeO2 catalyst is 143.8 m 2 / g, the average pore size is 6.7 nm, and the amount of Rh supported is 3 wt%.

[0051] Example 2

[0052] A mesoporous CeO2 supported Rh catalyst and a catalytic process for the hydroformylation of olefins using the same, the reaction flow of which is as follows:

number

[0053] The specific preparation method is as follows: The process includes the steps of placing 10 mg of the mesoporous Rh(0)-CeO2 catalyst obtained in Example 1, 0.5 mmol of styrene, and 4 mL of dioxane into a reactor, passing 0.5 MPa synthesis gas (CO / H2=1:1) through the reactor three times to replace the atmosphere, and then passing 2 MPa synthesis gas (CO / H2=1:1) through the reactor to catalyze the hydroformylation reaction in a closed system at 120°C for 8 hours, thereby completing the hydroformylation of olefins.

[0054] Gas chromatographic analysis showed that the styrene conversion was 100% and the yield of the product aldehyde was 98%.

[0055] Examples 3-13

[0056] A mesoporous CeO2 supported Rh catalyst and a catalytic process for the hydroformylation of olefins using the same, The mesoporous Rh(0)-CeO2 catalyst obtained in Example 1 was placed in a reactor with 10 mg, 0.5 mmol of olefin, and 4 mL of dioxane. The reactor was then purged with 0.5 MPa synthesis gas (CO / H2=1:1) three times, and then 2 MPa synthesis gas (CO / H2=1:1) was passed through. The hydroformylation reaction was catalyzed in a closed system at 120°C for 8 hours, and the olefin conversion rate and the yield of the product aldehyde were analyzed by gas chromatography. The types of olefins and product aldehydes, as well as the results of the olefin conversion rate and the yield of the product aldehyde are shown in Table 1.

[0057] [Table 1]

[0058] Example 14

[0059] A mesoporous CeO2 supported Rh catalyst and a catalytic process for the hydroformylation of olefins using the same, The mesoporous Rh(0)-CeO2 catalyst used in Example 2 was filtered and separated, and then placed in a reactor containing 0.5 mmol of olefin and 4 mL of dioxane, and substituted three times with 0.5 MPa synthesis gas (CO / H2=1:1), and then 2 MPa synthesis gas (CO / H2=1:1) was passed through to catalyze the hydroformylation reaction in a closed system at 120 ° C for 8 hours. The above recycling process was repeated, and the styrene conversion rate and the yield of the product aldehyde were analyzed by gas chromatography. The results are shown in Table 2.

[0060] [Table 2]

[0061] As can be seen from Table 2, the catalytic activity of the Rh(0)-CeO2 catalyst is maintained after 8 recovery cycles, and the catalytic activity starts to decrease after 9 recovery cycles. Therefore, the catalyst provided by the present invention has good reusability, which can greatly reduce the production cost of catalyzing olefin hydroformylation.

[0062] Example 15

[0063] The difference between the catalyst of this embodiment and that of Example 1 is the amount of Rh supported. In this embodiment, the amount of Rh supported is 1 wt%, and the preparation method is the same as that of Example 1. However, the mesoporous CeO2 support material and Rh 3+ The difference is that the mass ratio of is 100: 1. When the hydroformylation of styrene was catalyzed by the method of Example 2 and the reaction was carried out for 8 hours, the conversion of styrene was 43% and the selectivity of the product aldehyde was 99%.

[0064] Example 16

[0065] The difference between the catalyst of this embodiment and that of Example 1 is the amount of Rh supported. In this embodiment, the amount of Rh supported is 2 wt%. The preparation method is the same as that of Example 1, but the mesoporous CeO2 support material and Rh 3+ The difference is that the mass ratio of is 100: 2. When the hydroformylation of styrene was catalyzed by the method of Example 2 and the reaction was carried out for 8 hours, the conversion rate of styrene was 74% and the selectivity of the product aldehyde was 99%.

[0066] The above are only preferred specific embodiments of the present application, but the scope of protection of the present application is not limited thereto, and any changes or replacements that a person skilled in the art can easily conceive within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the scope of the claims.

Claims

1. Mesoporous CeO prepared by hydrothermal synthesis ２ After the support material was prepared, the high specific surface area mesoporous Rh(0)-CeO was prepared by the immersion-reduction method. ２ The mesoporous CeO catalyst is characterized by comprising a step of preparing the catalyst. ２ Method for preparing supported Rh catalyst.

2. Mesoporous CeO ２ The process for preparing the support material is to add Ce(NO ３ ) ３ ・6H ２ O was added and mixed by stirring, and then a hydrothermal reaction was carried out to obtain the mesoporous CeO ２ The mesoporous CeO of claim 1, further comprising a step of obtaining a support material. ２ Method for preparing supported Rh catalyst.

3. The diluted ammonia water is obtained by mixing concentrated ammonia water and water in a volume ratio of 13.5:108; The concentration of the concentrated ammonia water is 28%. The concentrated ammonia water and Ce(NO ３ ) ３ ・6H ２ The mesoporous CeO of claim 2, wherein the ratio of the amount of O added is 13.5 ml:0.74 g. ２ Method for preparing supported Rh catalyst.

4. The mesoporous CeO of claim 2, wherein the hydrothermal reaction is carried out at a temperature of 75° C. for 24 hours. ２ Method for preparing supported Rh catalyst.

5. The immersion-reduction method was used to prepare Rh(0)-CeO ２ The process for preparing the mesoporous CeO ２ Dispersion of support material and RhCl ３ ・3H ２ After mixing with the O solution, it is immersed, completely immersed, dried, and then H ２ and Ar mixed gas atmosphere to carry out a reduction reaction, ２ The mesoporous CeO catalyst of claim 1, further comprising a step of: ２ Method for preparing supported Rh catalyst.

6. The mesoporous CeO ２ The concentration of the dispersion of the carrier material is 10 mg / ml and the solvent is ethanol; RhCl ３ ・3H ２ Rh in O solution ３＋ The mesoporous CeO of claim 5 has a concentration of 1.2 mg / ml and the solvent is ethanol. ２ Method for preparing supported Rh catalyst.

7. The mesoporous CeO ２ Support material and Rh ３＋ The mesoporous CeO according to claim 5, wherein the mass ratio of ２ Method for preparing supported Rh catalyst.

8. The temperature of the reduction reaction was 300° C., and the time was 2 hours. ２ The mesoporous CeO of claim 5, wherein the volume ratio of CeO to Ar is 1:

3. ２ Method for preparing supported Rh catalyst.

9. The mesoporous CeO according to any one of claims 1 to 8, characterized in that the amount of Rh supported is 1 to 3 wt%. ２ Mesoporous CeO prepared by the method for preparing supported Rh catalyst ２ Supported Rh catalyst.

10. The mesoporous CeO of claim 9 for catalyzing the hydroformylation of olefins. ２ Use of supported Rh catalyst.

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