Pd / sio2-n-p catalyst and use thereof

Abstract

The application belongs to the technical field of catalysts, and particularly relates to a Pd / SiO2-N-P catalyst and application thereof. The Pd / SiO2-N-P catalyst is a N and P double modified silica gel supported Pd catalyst, and its preparation steps are as follows: (1) a nitrogen-containing compound and a phosphine-containing compound are respectively added into a reaction container, then an oxidizing agent and a solvent are added, and stirring reaction is carried out, so that a carrier precursor is obtained after reaction; (2) a solvent, the carrier precursor and a silica gel activator are respectively added into the silica gel after vacuum activation, stirring reaction is carried out, and a SiO2-N-P carrier is obtained after reaction; and (3) the SiO2-N-P carrier and a Pd compound are respectively added into a solvent, and then impregnation is carried out, so that the Pd / SiO2-N-P catalyst is obtained. The prepared catalyst has the advantages of high stability, easy product separation, and repeated use of the catalyst, and has a wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a Pd / SiO2-N-P catalyst and application thereof. BACKGROUND

[0002] Methyl methacrylate (MMA) is an important basic organic chemical raw material, which is widely used in many fields such as automobiles, construction, medicine, electronics and electrical appliances, textile printing and dyeing, coatings, adhesives, leather treatment chemicals, resin processing and the like. The most important use is to produce polymethyl methacrylate (PMMA), polyvinyl chloride processing impact modifier acrylate copolymer (ACR), methyl methacrylate-butadiene-styrene terpolymer (MBS) and as a second monomer for acrylic, which is an important chemical raw material indispensable for the development of national economy. At present, the global MMA product has formed various chemical process technology routes such as C2 route, C3 route and C4 route. Among them, the C2 route has the advantages of green, environmental protection, short process route and high yield, therefore, it has attracted widespread attention of researchers. The first step reaction is ethylene carbonylation reaction. Although many transition metals are effective catalysts for the reaction, the application of palladium complexes is the most widely used. In the homogeneous reaction kettle, under mild conditions, palladium complexes provide high activity and high selectivity for the hydroesterification of olefins. Although the homogeneous system performs well in catalytic efficiency, but due to the difficulty in catalyst separation and reusability, it seriously limits its industrialization process. In order to solve these problems, supported palladium catalysts have attracted widespread attention.

[0003] Supported palladium catalysts have attracted widespread attention in recent years because they combine the advantages of homogeneous and heterogeneous catalytic reactions. Pd complexes can be fixed on montmorillonite, graphite and silicon dioxide carriers and can be used for the hydroesterification of olefins. However, the anchoring effect of montmorillonite, graphite and silicon dioxide carriers on Pd is relatively weak, and there is a problem of Pd loss, which leads to a decrease in the recovery and utilization efficiency of Pd. Therefore, it is an urgent technical problem to develop a supported catalyst that can effectively enhance the anchoring ability of Pd complexes on the carrier, reduce Pd loss and improve the stability and recovery and utilization efficiency of Pd catalysts. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a Pd / SiO2-N-P catalyst, which has the advantages of high stability, easy separation of products, reusable catalyst and the like, and has a wide industrial application prospect.

[0005] Another purpose of the present application is to provide an application of the Pd / SiO2-N-P catalyst.

[0006] The technical solutions adopted by the present application are as follows:

[0007] The Pd / SiO2-N-P catalyst is a N and P double modified silica gel supported Pd catalyst, and its preparation method has the following steps:

[0008] (1) A nitrogen-containing compound (calculated as N) and a phosphine-containing compound (calculated as P) with a molar ratio of 1: (2-4) are added to a reaction container, then a solvent and an oxidizing agent are added under an inert atmosphere, and stirring reaction is carried out, after the reaction is completed, the solvent is removed by rotary evaporation, and the obtained product is extracted with anhydrous diethyl ether to obtain a carrier precursor;

[0009] (2) Silica gel is weighed and vacuumized at 100°C, N2 is passed, and then the solvent, the carrier precursor and the silica gel activator are added to the vacuumized and activated silica gel, stirring reaction is carried out, after the reaction is completed, it is cooled to room temperature, then washed with ethanol by centrifugation for 3 times, and dried to obtain a SiO2-N-P carrier;

[0010] (3) The SiO2-N-P carrier and the Pd compound are added to the solvent, impregnated under argon protection, filtered, washed, and dried to obtain the Pd / SiO2-N-P catalyst, wherein the mass ratio of the Pd element content in the Pd compound to the SiO2-N-P carrier is (10-50): 1 mg / g.

[0011] The Pd element content in the Pd / SiO2-N-P catalyst is 1-100 mg / g.

[0012] In the step (1), the nitrogen-containing compound is one of N-[3-(trimethoxysilyl)propyl]ethylenediamine, N-[3-(trimethoxysilyl)propyl]butan-1-amine, 3-aminopropyl triethoxysilane or N-aminoethyl-γ-aminopropyl triethoxysilane.

[0013] In the step (1), the phosphine-containing compound is one of diphenylphosphine, diphenylphosphine chloride or methoxydiphenylphosphine.

[0014] In the step (1), the solvent is one of deionized water, tetrahydrofuran, ethanol or toluene; the stirring reaction temperature is 60-120°C, and the time is 6-24h.

[0015] In the step (1), the oxidizing agent is 1,4-benzoquinone or sodium hypochlorite, and the molar ratio of the oxidizing agent to the phosphine-containing compound is (1-3): 1.

[0016] In the step (2), the solvent is one of toluene, diethyl ether, n-hexane or tetrahydrofuran, the addition amount of the solvent is 10-50 mL / g based on the volume mass ratio of the silica gel; the stirring reaction temperature is 50-120°C, and the time is 12-24h.

[0017] The step (2) is characterized in that the silica gel activator is one of triethylamine, ethylenediamine, hydrochloric acid or acetic acid, and the adding amount of the silica gel activator is 1-20 wt.% of the total amount of the silica gel.

[0018] The step (3) is characterized in that the Pd compound is one of palladium acetate, palladium chloride or palladium acetylacetonate.

[0019] The step (3) is characterized in that the solvent is one of methanol, toluene, acetone or deionized water; the impregnation temperature is 50-120 DEG C, and the time is 6-72 h.

[0020] The present application is characterized in that the nitrogen-containing compound is reacted with an oxidant and a phosphine-containing compound to obtain a trisilyl-functionalized bidentate phosphine ligand, and then the trisilyl-functionalized bidentate phosphine ligand is reacted with silica gel to obtain a carrier containing phosphine and nitrogen, and then a Pd compound is impregnated on the carrier to obtain a Pd / SiO2-N-P catalyst, which is used in the hydroesterification of olefins.

[0021] The Pd / SiO2-N-P catalyst is used in the hydroesterification of olefins.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] (1) In the present application, the phosphine and nitrogen are fixed on the silica gel carrier, on the one hand, the existence of the nitrogen can stabilize the Pd compound, inhibit the aggregation of the Pd compound in the reaction process, effectively solve the problem that the traditional Pd catalyst is easy to aggregate to form Pd black, and maintain the long-term activity and stability of the catalyst; on the other hand, the strong coordination between the Pd and the phosphine can strengthen the interaction between the catalyst and the carrier, further prevent the loss of the Pd in the reaction system, and ensure the efficient use of the catalyst.

[0024] (2) As a heterogeneous catalyst, the present application uses silica gel as the carrier, which can significantly promote the physical separation between the catalyst system and the reaction raw materials and products. This characteristic not only simplifies the subsequent product purification step, reduces the separation energy consumption, but also realizes the efficient recovery and reuse of the catalyst. Compared with the homogeneous catalyst, the Pd / SiO2-N-P catalyst system of the present application has great advantages in saving cost and improving production efficiency.

[0025] (3) The Pd / SiO2-N-P catalyst system of the present application has excellent performance in the hydroesterification reaction of olefins, can meet the needs of industrial production for high-efficiency, stable and easy-to-recover catalysts, and has a broad application prospect. DETAILED DESCRIPTION

[0026] The present application is further described below in conjunction with examples, but it does not limit the implementation of the present application.

[0027] The raw materials used in the examples and comparative examples are all conventional commercially available raw materials unless otherwise specified, and the process methods used in the examples and comparative examples are all conventional methods in the art unless otherwise specified.

[0028] Example 1

[0029] The preparation method of the Pd / SiO2-N-P catalyst is as follows:

[0030] (1) In a 50 mL three-necked flask, 0.04 mol of 3-aminopropyl triethoxysilane and 0.08 mol of diphenylphosphine were added, and replaced with argon for three times, and then 0.1 mol of 1,4-benzoquinone and 120 mL of toluene were added under the protection of argon, and stirred at 120℃ for 6 h. After the reaction was completed, toluene was removed by rotary evaporation (temperature was 110℃, pressure was 0.09 MPa), and the obtained product was extracted with anhydrous diethyl ether to obtain a carrier precursor;

[0031] (2) 5g of silica gel was activated by vacuum at 100℃ for 3h, and N2 was passed. To the vacuum-activated silica gel, 150 mL of toluene, 0.5g of the carrier precursor and concentrated hydrochloric acid (containing 0.05g of HCl) were added, and stirred at 120℃ for 12h of condensation reflux. After the reaction was completed, it was cooled to room temperature, then washed with ethanol by centrifugation for 3 times (the speed of each centrifugation was 1000rpm, and the time was 3min), and dried to obtain the SiO2-N-P carrier;

[0032] (3) 5g of the SiO2-N-P carrier and 84mg of palladium chloride were added to 30 mL of acetone, and immersed at 50℃ for 72h under the protection of argon, then filtered, washed and dried to obtain the Pd / SiO2-N-P catalyst.

[0033] The above Pd / SiO2-N-P catalyst was used for the hydroesterification reaction of olefins to prepare organic carboxylic acid esters, and the preparation steps were as follows:

[0034] In a 250ml high-pressure reactor, 1g of Pd / SiO2-N-P catalyst, 100ml of methanol, 2.5g of methanesulfonic acid and 0.08mol of ethylene were added respectively, the reactor was closed, the reactor was replaced with CO for 3 times, and then CO was filled into the reactor until the pressure of the reactor was 4MPa. The temperature was slowly increased to 110°C by a temperature controller, and the reaction was carried out for 4h. After cooling to room temperature, the reactor was unloaded, and the liquid obtained by the reaction was quantitatively analyzed by Agilent6890. The conversion rate of ethylene was 98%, and the selectivity of the product methyl propionate was 99%.

[0035] Pd / SiO2-N-P catalyst repeatability test:

[0036] The prepared Pd / SiO2-N-P catalyst was used for olefin hydroesterification reaction to prepare organic carboxylic acid ester, and was reused for 10 times. The conversion rate of ethylene was 98%, 97%, 98%, 96%, 96%, 97%, 96%, 95%, 95%, and 95% respectively, and the selectivity of the product methyl propionate was 99%, 99%, 99%, 98%, 99%, 99%, 99%, 98%, 98%, and 98% respectively.

[0037] Example 2

[0038] The preparation method of the Pd / SiO2-N-P catalyst is as follows:

[0039] (1) In a 50ml three-necked flask, 0.04mol of N-[3-(trimethoxysilyl)propyl]ethylenediamine and 0.16mol of diphenylphosphine chloride were added, and the flask was replaced with argon for three times. Under the protection of argon, 0.48mol of 1,4-benzoquinone and 120ml of deionized water were added, and the mixture was stirred at 100°C for 12h. After the reaction was completed, the deionized water was removed by rotary evaporation (temperature 95°C, pressure 0.09MPa), and the obtained product was extracted with anhydrous ether to obtain a carrier precursor;

[0040] (2) 5g of silica gel was activated by vacuum at 100°C for 3h, and then N2 was introduced. 50ml of ether, 2.5g of the carrier precursor and 1g of triethylamine were added to the vacuum-activated silica gel, and the mixture was stirred at 50°C for 24h. After the reaction was completed, the mixture was cooled to room temperature, and then washed with ethanol by centrifugation for 3 times (the speed of each centrifugation was 1000rpm, and the time was 3min). The mixture was dried to obtain a SiO2-N-P carrier;

[0041] (3) 5g of the SiO2-N-P carrier and 527.4mg of palladium acetate were added to 30ml of deionized water, and the mixture was immersed at 100°C for 12h under the protection of argon. The mixture was filtered, washed and dried to obtain a Pd / SiO2-N-P catalyst.

[0042] The Pd / SiO2-N-P catalyst is used for olefin hydroesterification reaction to prepare organic carboxylic acid ester, and the preparation steps are as follows:

[0043] In a 250ml high-pressure reactor, 1g of Pd / SiO2-N-P catalyst, 100ml of methanol, 2.5g of methanesulfonic acid and 0.08mol of styrene were added, the reactor was closed, the reactor was replaced with CO for 3 times, and then CO was filled into the reactor to a pressure of 3MPa. The temperature was slowly increased to 110℃ controlled by the temperature controller, and the reaction was carried out for 4h. After cooling to room temperature, the reactor was unloaded, and the reaction liquid was quantitatively analyzed by Agilent 6890. The conversion rate of styrene was 96%, and the selectivity of product methyl phenylpropionate was 99%.

[0044] Example 3

[0045] The preparation method of the Pd / SiO2-N-P catalyst is as follows:

[0046] (1) In a 50ml three-necked flask, 0.04mol of N-[3-(trimethoxysilyl)propyl]butan-1-amine and 0.08mol of methoxydiphenylphosphine were added, and the flask was replaced with argon for three times. Under the protection of argon, 0.08mol of sodium hypochlorite and 120ml of ethanol were added, and the mixture was stirred at 60℃ for 24h. After the reaction was completed, ethanol was removed by rotary evaporation (temperature 70℃, pressure 0.09MPa), and the obtained product was extracted with anhydrous diethyl ether to obtain a carrier precursor;

[0047] (2) 5g of silica gel was activated by vacuum at 100℃ for 3h, and then N2 was introduced. 250ml of n-hexane, 5g of the carrier precursor and 0.5g of ethylenediamine were added to the activated silica gel, and the mixture was stirred at 70℃ for 16h. After the reaction was completed, the mixture was cooled to room temperature, and then washed with ethanol by centrifugation for 3 times (the speed of each centrifugation was 1000rpm, and the time was 3min). The mixture was dried to obtain a SiO2-N-P carrier;

[0048] (3) 5g of the SiO2-N-P carrier and 350mg of palladium acetylacetonate were added to 30ml of methanol, and the mixture was immersed at 80℃ for 24h under the protection of argon. After filtration, washing and drying, the Pd / SiO2-N-P catalyst was obtained.

[0049] The Pd / SiO2-N-P catalyst is used for olefin hydroesterification reaction to prepare organic carboxylic acid ester, and the preparation steps are as follows:

[0050] In a 250ml high-pressure reactor, 1g of Pd / SiO2-N-P catalyst, 100ml of methanol, 2.5g of methanesulfonic acid and 0.2mol of ethylene were added respectively, the reactor was closed, the reactor was replaced with CO for 3 times, and then CO was filled into the reactor until the pressure of the reactor was 2MPa. The temperature was slowly increased to 100℃ by the temperature controller, and the reaction was carried out for 4h. After cooling to room temperature, the reactor was unloaded, and the liquid obtained by the reaction was quantitatively analyzed by Agilent6890. It was measured that the conversion rate of styrene was 97%, and the selectivity of the product methyl phenylacetate was 99%.

[0051] Example 4

[0052] The preparation method of the Pd / SiO2-N-P catalyst is as follows:

[0053] (1) In a 50ml three-necked flask, 0.04mol of N-aminoethyl-γ-aminopropyl triethoxysilane and 0.16mol of diphenylphosphine were added, and the flask was replaced with argon for 3 times. Then, 0.2mol of 1,4-benzoquinone and 120ml of tetrahydrofuran were added under the protection of argon, and the mixture was stirred at 70℃ for 12h. After the reaction was completed, tetrahydrofuran was removed by rotary evaporation (temperature was 60℃, pressure was 0.09MPa), and the obtained product was extracted with anhydrous ether to obtain a carrier precursor;

[0054] (2) 5g of silica gel was activated at 100℃ under vacuum for 3h, and then N2 was introduced. Then, 200ml of tetrahydrofuran, 1g of the carrier precursor and 1g of acetic acid were added to the activated silica gel, and the mixture was stirred at 80℃ for 12h under reflux. After the reaction was completed, the mixture was cooled to room temperature, and then washed with ethanol by centrifugation for 3 times (the speed of centrifugation was 1000rpm, and the time was 3min). Finally, the mixture was dried to obtain a SiO2-N-P carrier;

[0055] (3) 5g of the SiO2-N-P carrier and 150mg of palladium chloride were added to 30ml of toluene under the protection of argon, and the mixture was immersed at 120℃ for 6h. Then, the mixture was filtered, washed and dried to obtain the Pd / SiO2-N-P catalyst.

[0056] The Pd / SiO2-N-P catalyst was used for olefin hydroesterification reaction to prepare organic carboxylate, and the preparation steps were as follows:

[0057] In a 250ml high-pressure reactor, 1g of Pd / SiO2-N-P catalyst, 100ml of ethanol, 2.5g of methanesulfonic acid and 0.1mol of ethylene were added respectively, the reactor was closed, the reactor was replaced with CO for 3 times, and then CO was filled into the reactor until the pressure of the reactor was 2MPa. The temperature was slowly increased to 110°C by a temperature controller, and the reaction was carried out for 4h. After cooling to room temperature, the reactor was unloaded, and the liquid obtained by the reaction was quantitatively analyzed by Agilent 6890. The conversion rate of ethylene was 95%, and the selectivity of the product methyl propionate was 98%.

[0058] Comparative Example 1

[0059] Into 30ml of acetone, 5g of silica gel and 83mg of palladium chloride were added respectively, and heated at 50°C for 72h under argon protection, washed and dried to obtain a Pd / SiO2 catalyst.

[0060] The above Pd / SiO2 catalyst was used for olefin hydroesterification reaction to prepare organic carboxylic acid ester, and the preparation steps were the same as in Example 1. The liquid obtained by the reaction was quantitatively analyzed by Agilent 6890. The conversion rate of ethylene was 58%, and the selectivity of the product methyl propionate was 90%.

[0061] Pd / SiO2 catalyst repeatability test:

[0062] The prepared Pd / SiO2 catalyst was used for olefin hydroesterification reaction to prepare organic carboxylic acid ester, and the catalyst was deactivated after being reused for 3 times. The conversion rate of ethylene was 58%, 27% and 0 respectively, and the selectivity of the product methyl propionate was 90%, 84% and 0 respectively.

[0063] Comparative Example 2

[0064] The difference from Example 1 was that 3-chloropropyl triethoxysilane was used instead of 3-aminopropyl triethoxysilane in step (1), and the other steps were the same as in Example 1. The conversion rate of ethylene was 67%, and the selectivity of the product methyl propionate was 89%.

[0065] Comparative Example 3

[0066] The difference from Example 1 was that no diphenylphosphine was added in step (1), and the other steps were the same as in Example 1. The conversion rate of ethylene was 0.

[0067] Comparative Example 4

[0068] The difference from Example 1 was that the amount of palladium chloride added in step (3) was 50mg, and the other steps were the same as in Example 1. The conversion rate of ethylene was 42%, and the selectivity of the product methyl propionate was 88%.

[0069] Comparative Example 5

[0070] The difference from Example 1 is that the amount of diphenylphosphine added in step (1) is 0.04 mol, and the other conditions are the same as in Example 1. The ethylene conversion is 52%, and the selectivity of the product methyl propionate is 92%.

Claims

1. A Pd / SiO2-N-P catalyst characterized in that, A Pd catalyst supported by silica gel modified by N and P, a preparation method thereof, and steps are as follows: (1) a nitrogen-containing compound and a phosphorus-containing compound in a molar ratio of 1:(2-4) are added into a reaction container, then an oxidizing agent and a solvent are added, stirring is carried out, and a carrier precursor is obtained after the reaction is completed; wherein the number of moles of the nitrogen-containing compound is calculated by N, and the number of moles of the phosphorus-containing compound is calculated by P; (2) a solvent, the carrier precursor and a silica gel activator are added into the silica gel after vacuum activation, stirring is carried out, and a SiO2-N-P carrier is obtained after the reaction is completed; (3) the SiO2-N-P carrier and a Pd compound are added into the solvent, and then impregnation is carried out, and thus a Pd / SiO2-N-P catalyst is obtained, wherein the mass ratio of the Pd element in the Pd compound to the SiO2-N-P carrier is (10-50):1 mg / g; the nitrogen-containing compound is one of N-[3-(trimethoxysilyl)propyl]ethylenediamine, N-[3-(trimethoxysilyl)propyl]butan-1-amine, 3-aminopropyltriethoxysilane or N-aminoethyl-γ-aminopropyltriethoxysilane; the phosphorus-containing compound is one of diphenylphosphine, diphenylphosphine chloride or methoxydiphenylphosphine; the oxidizing agent is 1,4-benzoquinone or sodium hypochlorite; the silica gel activator is one of triethylamine, ethylenediamine, hydrochloric acid or acetic acid.

2. The Pd / SiO2-N-P catalyst according to claim 1, characterized in that, in the step (1), the solvent is one of deionized water, tetrahydrofuran, ethanol or toluene; the stirring reaction temperature is 60-120 DEG C, and the time is 6-24 h.

3. The Pd / SiO2-N-P catalyst according to claim 1, characterized in that, in the step (1), the molar ratio of the oxidizing agent to the phosphorus-containing compound is (1-3):

1.

4. The Pd / SiO2-N-P catalyst of claim 1, wherein, in the step (2), the solvent is one of toluene, diethyl ether, n-hexane or tetrahydrofuran; the stirring reaction temperature is 50-120 DEG C, and the time is 12-24 h.

5. The Pd / SiO2-N-P catalyst of claim 1, wherein, in the step (2), the addition amount of the silica gel activator is 1-20 wt.% of the total amount of the silica gel.

6. The Pd / SiO2-N-P catalyst of claim 1, wherein, in the step (3), the Pd compound is one of palladium acetate, palladium chloride or palladium acetylacetonate.

7. The Pd / SiO2-N-P catalyst of claim 1, wherein, in the step (3), the solvent is one of methanol, toluene, acetone or deionized water; the impregnation temperature is 50-120 DEG C, and the time is 6-72 h.

8. Use of a Pd / SiO2-N-P catalyst according to any one of claims 1 to 7, characterized in that, The catalyst is used for olefin hydroesterification.