A method for preparing a recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst

Abstract

This invention discloses a method for preparing a recyclable supported Rh / g-C3N4 catalyst for the hydroformylation of olefins, belonging to the field of olefin hydroformylation reactions to prepare aldehydes. Based on previous research, this invention uses g-C3N4 as a support and loads the noble metal rhodium (Rh) as the active component onto g-C3N4 via ball milling to prepare an Rh / g-C3N4 catalyst. This catalyst has been applied to the hydroformylation reactions of various reactants, including 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, exhibiting good activity and stability. The catalyst can be recovered through simple filtration and drying.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a recyclable supported Rh / g-C3N4 olefin hydroformylation reaction catalyst and belongs to the field of olefin hydroformylation reaction for preparing aldehyde compounds. BACKGROUND

[0002] The olefin hydroformylation reaction, i.e. the hydroformylation reaction, is a reaction in which olefins are converted into aldehydes under the catalysis of a transition metal catalyst as a catalytically active center and under the action of a ligand and hydrogen and carbon monoxide. It is one of the most important catalytic reactions in industry, and the reaction product aldehyde is an intermediate of many chemical products. After further chemical reactions (such as hydrogenation, oxidation, reductive amination, etc.), alcohols, carboxylic acids, amines, esters and other valuable chemical substances are generated, or after hydroxy aldehyde condensation and acetal formation, various detergents, surfactants or medicines and perfumes and other high value-added fine chemicals are generated. The straight-chain aldehyde generated by the hydroformylation reaction is widely used in the industry for synthesizing detergents and plasticizers; the branched-chain aldehyde is widely used for synthesizing medicines and chemical reagents.

[0003] However, the hydroformylation reaction generates straight-chain and branched-chain hydroformylation products, and at the same time, other types of reactions occur, such as isomerization of olefins to generate isomerized olefins, or hydrogenation to generate corresponding alkanes; the homogeneous reaction system using an organic solvent also faces the problem of difficult separation of the catalyst and the product; in the reaction, the rhodium metal active center is easy to be deactivated, and the higher the temperature, the faster the deactivation. There are many researches on the olefin hydroformylation reaction process worldwide, mainly focusing on the optimal reaction conditions under the action of different catalysts and ligands, the preparation of new ligands for easy recovery of noble metals, the influence of new reaction containers on the reaction and the like.

[0004] The triphenylphosphine ligand is one of the oil-soluble ligands with better catalytic performance reported at present, and the existing rhodium catalyst has good catalytic effect on terminal olefins, but has poor activity on internal olefins. In order to improve the normal-isomer ratio of the product, a large excess of triphenylphosphine needs to be added. In recent years, the two-phase catalytic system using water as a solvent is relatively popular, and the catalyst is easy to recover, but for long-chain olefins with low water solubility, some solubilizers or surfactants need to be added to enhance the solubility of the long-chain olefins. Therefore, developing a solid-supported catalyst with good stability, high activity and mild reaction conditions has become the technical key of the olefin hydroformylation reaction. SUMMARY

[0005] The application aims to provide a preparation method of a recyclable supported Rh / g-C3N4 olefin hydroformylation reaction catalyst, so as to solve the problem of serious loss of rhodium in a rhodium-based supported catalyst and save the cost of industrial production.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] The application provides a preparation method of a recyclable supported Rh / g-C3N4 olefin hydroformylation reaction catalyst, which comprises the following steps: obtaining a g-C3N4 carrier by calcining dicyandiamide; loading noble metal rhodium on the g-C3N4 carrier by a wet ball milling method to obtain a catalyst semi-finished product loaded with noble metal rhodium; and placing the catalyst semi-finished product loaded with noble metal rhodium in a muffle furnace for calcination to obtain the recyclable supported Rh / g-C3N4 olefin hydroformylation reaction catalyst. 2 The specific surface area of the recyclable supported Rh / g-C3N4 olefin hydroformylation reaction catalyst is 20-21 m 2 / g, the average pore volume is 0.12 cm / g, and the loading amount of the noble metal rhodium accounts for 0.045wt%-0.052wt% of the supported Rh / g-C3N4 olefin hydroformylation reaction catalyst.

[0008] The preparation method of the recyclable supported Rh / g-C3N4 olefin hydroformylation reaction catalyst comprises the following steps:

[0009] S1: placing dicyandiamide in a porcelain boat and placing the porcelain boat in a muffle furnace for calcination, wherein the calcination atmosphere is air, the heating rate of calcination is 5℃ / min, the calcination temperature is 550℃, the calcination time is 4h, and a light yellow solid product, i.e., the g-C3N4 carrier, is obtained and is fully ground into a powder in an agate mortar;

[0010] S2: adding the g-C3N4 carrier powder, acetylacetone dicarbonyl rhodium and toluene into a ball milling tank, and alternately ball milling for 6h at a rotation speed of 500r / min; after the ball milling is completed, the filter residue is washed with a detergent for 3 times, the detergent is removed by filtration, and vacuum drying is performed to obtain the catalyst semi-finished product loaded with noble metal rhodium;

[0011] S3: The catalyst semi-finished amine supported on the precious metal rhodium was placed in a porcelain boat, and the porcelain boat was placed in a muffle furnace for calcination. The calcination atmosphere was air, the heating rate was 5℃ / min, the calcination temperature was 300℃, and the calcination time was 4h. A light yellow solid product was obtained, which is the recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst. It was then thoroughly ground into powder in an agate mortar.

[0012] The amount of the g-C3N4 carrier powder used is 1.1g, the amount of the acetylacetone dicarbonyl rhodium used is 0.011g, and the amount of the toluene used is 20mL.

[0013] The detergent is toluene;

[0014] The drying temperature is 100℃ and the time is 6 hours.

[0015] A recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst is prepared by the above-described preparation method.

[0016] The above-mentioned recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst is used in the olefin hydroformylation reaction, wherein the olefin is one or more selected from 1-butene, 1-pentene, 1-octene, 1-nonene, cyclohexene, and styrene; the olefin hydroformylation reaction is carried out in a reaction vessel at a reaction temperature of 110℃, a reaction pressure of 5MPa, a reaction time of 240min, and a reaction speed of 600r / min.

[0017] The significant advantages of this invention are:

[0018] (1) The preparation method of the carrier g-C3N4 is simple and efficient, and the raw materials are inexpensive and readily available;

[0019] (2) The g-C3N4 carrier provides sufficient specific surface area for the metal to be dispersed on its surface;

[0020] (3) The ball milling method ensures that the Rh metal particles are evenly distributed on the g-C3N4 support, and the catalyst is then calcined, which significantly improves the catalytic activity and stability of the catalyst. Attached Figure Description

[0021] Figure 1 XPS plot of Rh / g-C3N4 catalyst.

[0022] Figure 2 XPS plot of Rh / g-C3N4 catalyst after reaction with triphenylphosphine.

[0023] Figure 3 The image shows the XRD pattern of the Rh / g-C3N4 catalyst.

[0024] Figure 4 The BET plots are for the g-C3N4 support and the Rh / g-C3N4 catalyst. Detailed Implementation

[0025] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0026] In the following examples, the rhodium diacetylacetone was manufactured by Aladdin Company, CAS No.: 14874-82-9.

[0027] In the following embodiments, the synthesis gas is a mixture of CO and H2, wherein the volume ratio of CO to H2 is 1:1.

[0028] Example 1:

[0029] Weigh 4g of dicyandiamine and place it in a porcelain boat. Transfer the boat to a muffle furnace and heat it from room temperature to 550℃ at a rate of 5℃ / min. Calcinate the mixture at 550℃ for 4 hours in an air atmosphere. After calcination, cool the furnace to room temperature to obtain approximately 1.5g of pale yellow solid product, which is g-C3N4 carrier. Grind the g-C3N4 carrier into powder in an agate mortar.

[0030] Weigh 1.1 g g-C3N4 carrier powder and 0.011 g rhodium dicarbonyl acetylacetone (Rh(acac)(CO)2) and place them in a ball mill jar. Add 20 mL of toluene, seal the jar, and fix it on a planetary ball mill. Ball mill alternately for 6 hours at a speed of 500 r / min, alternating every 30 minutes. After ball milling, transfer the milled product to a Buchner funnel connected to a suction flask for filtration. Wash the filter residue three times with 10 mL of toluene as detergent to remove unloaded Rh(acac)(CO)2. Finally, filter to remove any residue containing Rh(acac)(CO)2. Most of the detergent was dried under vacuum at 100°C for 6 hours to obtain a rhodium-loaded catalyst semi-finished product. The rhodium-loaded catalyst semi-finished product was placed in a porcelain boat and transferred to a muffle furnace. The temperature was increased from room temperature to 300°C at a rate of 5°C / min, and calcined at 300°C for 4 hours in an air atmosphere to obtain approximately 1 g of a pale yellow solid product, namely the Rh / g-C3N4 catalyst (i.e., the recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst described in this invention). This solid was then thoroughly ground into powder in an agate mortar. The rhodium loading of this Rh / g-C3N4 catalyst was 0.0524 wt%, and its specific surface area and pore structure parameters are listed in Table 1.

[0031] Weigh 4 mL of 1-butene and 10 mL of toluene into a 100 mL quartz cup, add 1 g of Rh / g-C3N4 catalyst powder and 1 g of internal standard p-xylene, then place the quartz cup into a 100 mL high-temperature and high-pressure reactor. After assembling the reaction apparatus, check the airtightness of the apparatus. Replace the gas inside the reactor with syngas three times. After replacement, ensure that the pressure gauge reading is 0 MPa. Set the reactor temperature to 110℃ and the rotation speed to 600 r / min, then run the reactor to allow it to heat up and stir. When the reactor temperature reaches the set value, open the gas valve to raise the pressure inside the reactor to 5 MPa, and run it stably under this condition for 4 hours. After the operation was completed, the reactor automatically stopped stirring. Once the temperature in the reactor dropped to room temperature, the vent valve was opened to reduce the pressure inside the reactor to 0 MPa. Then, the reactor was opened, and the reaction solution in the quartz cup was removed. The product and Rh / g-C3N4 catalyst were separated by filtration. The quartz cup and reactor were washed and dried. 1 mL of the product (filtrate) was taken using a syringe equipped with a filter head for gas chromatography analysis. After drying the Rh / g-C3N4 catalyst in a vacuum drying oven (100℃, 6h), it was allowed to participate in the next reaction. The results of the cyclic reaction of the Rh / g-C3N4 catalyst are listed in Table 2.

[0032] Example 2:

[0033] Weigh 4g of dicyandiamine and place it in a porcelain boat. Transfer the boat to a muffle furnace and heat it from room temperature to 550℃ at a rate of 5℃ / min. Calcinate the mixture at 550℃ for 4 hours in an air atmosphere. After calcination, cool the furnace to room temperature to obtain approximately 1.5g of pale yellow solid product, which is g-C3N4 carrier. Grind the g-C3N4 carrier into powder in an agate mortar.

[0034] Weigh 1.1 g g-C3N4 carrier powder and 0.011 g rhodium dicarbonyl acetylacetone (Rh(acac)(CO)2) and place them in a ball mill jar. Add 20 mL of toluene, seal the jar, and fix it on a planetary ball mill. Ball mill alternately for 6 hours at a speed of 500 r / min, alternating every 30 minutes. After ball milling, transfer the milled product to a Buchner funnel connected to a suction flask for filtration. Wash the filter residue three times with 10 mL of toluene as detergent to remove unloaded Rh(acac)(CO)2. Finally, filter to remove any residue containing Rh(acac)(CO)2. The majority of the detergent was dried under vacuum at 100°C for 6 hours to obtain a rhodium-supported catalyst semi-finished product. This rhodium-supported catalyst semi-finished product was placed in a porcelain boat and transferred to a muffle furnace. The temperature was increased from room temperature to 300°C at a rate of 5°C / min, and calcined at 300°C for 4 hours in an air atmosphere, yielding approximately 1 g of a pale yellow solid product, namely the Rh / g-C3N4 catalyst (i.e., the recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst described in this invention). This solid was then thoroughly ground into powder in an agate mortar. The rhodium loading of this Rh / g-C3N4 catalyst was 0.0524 wt%.

[0035] Weigh 4 mL of 1-butene and 10 mL of toluene into a 100 mL quartz cup. Add 1 g of Rh / g-C3N4 catalyst powder, 2.85 g of triphenylphosphine (PPh3), and 1 g of p-xylene (internal standard). Place the quartz cup into a 100 mL high-temperature and high-pressure reactor. After assembling the reaction apparatus, check its airtightness. Replace the gas inside the reactor with syngas three times. After replacement, ensure the pressure gauge reading is 0 MPa. Set the reactor temperature to 110 °C and the rotation speed to 600 r / min. Then run the reactor to allow it to heat up and stir. Once the reactor temperature reaches the set value, open the gas valve to raise the pressure inside the reactor to 5 MPa. Run the reactor stably under this condition for 4 hours. h; After the operation is completed, the reactor automatically stops stirring. When the temperature in the reactor drops to room temperature, the vent valve is opened to reduce the pressure inside the reactor to 0 MPa. Then, the reactor is opened, the reaction solution in the quartz cup is removed, and the product and Rh / g-C3N4 catalyst are separated by filtration. The quartz cup and reactor are washed and dried. 1 mL of product (i.e., filtrate) is taken using a syringe equipped with a filter head for gas chromatography analysis. After drying the Rh / g-C3N4 catalyst in a vacuum drying oven (100℃, 6h), it continues to participate in the next reaction, with triphenylphosphine added again for each reaction. The results of the combined use of Rh / g-C3N4 catalyst and triphenylphosphine ligand in the cyclic reaction are listed in Table 3.

[0036] Table 1. Specific surface area and pore structure parameters of g-C3N4 and Rh / g-C3N4

[0037] Sample S BET (m 2 ·g -1 )]]> V A (cm 3 ·g -1 )]]> g-C3N4 20.71 0.12 [Rh / g-C3N4] 21.50 0.13

[0038] Table 2. Effect of cyclic reaction on the catalytic performance of Rh / g-C3N4

[0039]

[0040] Table 3. Effect of triphenylphosphine on the cyclic reaction efficiency of Rh / g-C3N4 catalyst

[0041]

[0042] Straight chain ratio (%) = (n 正戊醛 / n 戊醛 )×100%

[0043] XPS characterization results show that, without the addition of triphenylphosphine, Rh 3d 5 / 2 The binding energy in the Rh / g-C3N4 catalyst is 309.4–310.2 eV, indicating the presence of Rh metal particles. 3+ state; while Rh 3d 3 / 2 The binding energy is 313.5–314.4 eV, indicating the presence of Rh oxides. This may be because Rh(acac)(CO)₂ itself possesses O atoms, or it may be due to the catalyst being exposed to air for a long time during preparation and testing, leading to partial oxidation. After the addition of triphenylphosphine, Rh 3d 5 / 2 The binding energy peak decreased from 309.6 eV to 308.7 eV, indicating that under the action of triphenylphosphine, the outer electron cloud density of Rh atoms increased and the electron-donating ability was enhanced, thereby improving the catalyst performance.

[0044] The XRD test results show that the g-C3N4 structure is very stable. Whether before or after the reaction or after the addition of triphenylphosphine, the characteristic diffraction peaks of the (100) crystal plane at about 13.1° and the (002) crystal plane at about 27.4° remain unchanged. However, due to the low loading of metal Rh, no characteristic diffraction peaks of Rh were observed in the XRD test.

[0045] As shown in Table 2, the Rh / g-C3N4 catalyst exhibits good catalytic activity in the hydroformylation of 1-butene. Based on the cycling effect and the ICP-OES test results of the reaction solution, the Rh / g-C3N4 catalyst has excellent stability, and the loss rate of rhodium metal in each reaction is less than 2 ppm.

[0046] To improve the effect of the Rh / g-C3N4 catalyst on the linear chain ratio of the reaction, in Example 2 we added phosphine ligands to synergize with the Rh / g-C3N4 catalyst, which effectively improved the linear chain ratio. Moreover, the Rh / g-C3N4 catalyst was not affected by the phosphine ligands, and the active component Rh was not lost into the solvent due to complexation with the phosphine ligands. According to the ICP-OES results of the reaction solution, the loss rate of rhodium metal in each reaction was less than 1 ppm.

[0047] Based on the research on the hydroformylation reaction of 1-butene, the switching frequency of the Rh / g-C3N4 catalyst is basically maintained between 4600 and 4900 h⁻¹. -1 Within this range, compared to the 1916h reported by Jiang Fuhong et al., -1 465h reported by Jiang Weili and others -1 According to Tian Jianxing's report of 16.2h -1 All should be high. Note: The content of the report by Jiang Fuhong et al. is based on "Study on 1-Butene Hydroformylation Reaction", the content of the report by Jiang Weili et al. is based on "Influencing Factors of 1-Butene Hydroformylation Reaction to Pentanal", and the content of the report by Tian Jianxing is based on "Study on the Preparation of Pentanal by 1-Butene Hydroformylation Catalyzed by ZIF-67 Derivative Materials".

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst, characterized in that: g-C3N4 support was obtained by calcining dicyandiamine; rhodium was loaded onto the g-C3N4 support by wet ball milling to obtain a rhodium-loaded catalyst semi-finished product; the rhodium-loaded catalyst semi-finished product was placed in a muffle furnace for calcination to obtain a recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst. The preparation method steps are as follows: S1: Dicyandiamine was placed in a porcelain boat, and the porcelain boat was placed in a muffle furnace for calcination. The calcination atmosphere was air, the heating rate was 5℃ / min, the calcination temperature was 550℃, and the calcination time was 4h. A pale yellow solid product was obtained, which is g-C3N4 support. It was then fully ground into powder in an agate mortar. S2: Add g-C3N4 support powder, rhodium dicarbonyl acetylacetone and toluene to a ball mill jar, and ball mill alternately for 6 hours at a speed of 500 r / min. After ball milling, filter the residue, wash the residue three times with detergent, remove the detergent by vacuum filtration, and dry it under vacuum to obtain a catalyst semi-finished product supported on the precious metal rhodium. S3: The catalyst semi-finished product supported on precious metal rhodium is placed in a porcelain boat, and the porcelain boat is placed in a muffle furnace for calcination. The calcination atmosphere is air, the heating rate is 5℃ / min, the calcination temperature is 300℃, and the calcination time is 4h. A light yellow solid product is obtained, which is the recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst. It is then thoroughly ground into powder in an agate mortar.

2. The method for preparing a recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst according to claim 1, characterized in that: The supported Rh / g-C3N4 olefin hydroformylation catalyst has a specific surface area of ​​20~21 m². 2 / g, average pore volume is 0.12cm³ 3 / g; the loading of the precious metal rhodium accounts for 0.045wt%~0.052wt% of the supported Rh / g-C3N4 olefin hydroformylation catalyst.

3. The method for preparing a recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst according to claim 1, characterized in that: The amount of the g-C3N4 carrier powder used is 1.1g, the amount of the acetylacetone dicarbonyl rhodium used is 0.011g, and the amount of toluene used is 20mL.

4. The method for preparing a recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst according to claim 1, characterized in that: The detergent is toluene.

5. The method for preparing a recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst according to claim 1, characterized in that: The drying temperature is 100℃ and the time is 6 hours.

6. A recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the recyclable supported Rh / g-C3N4 olefin hydroformylation catalyst according to claim 6 in the olefin hydroformylation reaction, characterized in that: The olefin is one or more selected from 1-butene, 1-pentene, 1-octene, 1-nonene, cyclohexene, and styrene; the olefin hydroformylation reaction is carried out in a reaction vessel at a reaction temperature of 110°C, a reaction pressure of 5 MPa, a reaction time of 240 min, and a reaction speed of 600 r / min.

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