Porphyrin-based diatomic catalyst for preparing ethylene through acetylene hydrogenation as well as preparation method and application of porphyrin-based diatomic catalyst
By using porphyrin-based diatomic catalysts in the acetylene semihydrogenation reaction, the problems of poor activity and stability of single atomic catalysts are solved, and efficient and stable ethylene generation is achieved.
Patent Information
- Application Number
- CN202411870638.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-05-06
AI Technical Summary
In the acetylene semihydrogenation reaction, the single-atom catalyst has problems such as poor activity and poor high temperature stability, making it difficult to achieve high ethylene selectivity and high reactivity while maintaining stability.
Using a porphyrin-based diatomic catalyst, 5-bromo-10,15,20-triphenyl porphyrin is synthesized and reacted with a metal salt to form bimetal porphyrin, and then supported on a support and carbonized at high temperature to obtain a diatomic catalyst for hydrogenation of acetylene.
The hydrogenation stability of the catalyst is significantly improved, and the efficient formation of ethylene is achieved, with high ethylene yield, high selectivity and high stability.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of green chemical industry, and specifically relates to a porphyrin-based diatomic catalyst for preparing ethylene by hydrogenating acetylene. The present invention also relates to a preparation method and application of the catalyst. Background Art
[0002] Ethylene is one of the important raw materials in chemical production, mainly used in the production of polyethylene. It is also an intermediate commonly used in the pharmaceutical, agricultural and fine chemical industries. However, a small amount of acetylene is generated during the industrial cracking process to produce ethylene, which can poison the catalyst of the downstream ethylene polymerization reaction. Therefore, acetylene needs to be removed before the polymerization reaction. Among the many production methods, the selective hydrogenation of acetylene to produce ethylene is considered to be the most efficient, environmentally friendly and economical strategy.
[0003] In the semi-hydrogenation of acetylene, single-atom catalysts have unique catalytic properties, but they also have the disadvantages of poor activity and poor high-temperature stability. Therefore, it is challenging to achieve high ethylene selectivity while maintaining high reactivity and stability. Porphyrin is a conjugated macrocyclic structure. A variety of metalloporphyrins can be obtained by changing the substituents on its ring and the central metal. It has very wide applications in the field of catalysis. Porphyrin-based single-atom catalysts show excellent chemical selectivity and regioselectivity in the conversion of alkynes to alkenes. Compared with single-atom catalysts (SACs), diatomic catalysts (DACs) have more flexible active sites, unique electronic structures and synergistic atomic interactions, and may have great potential to improve catalytic performance. Summary of the invention
[0004] The purpose of the present invention is to provide a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene, provide a preparation method of the porphyrin-based diatomic catalyst and have good reaction activity, selectivity and stability for the selective hydrogenation of acetylene.
[0005] To this end, the first technical solution provided by the present invention is as follows:
[0006] A method for preparing a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene comprises the following steps:
[0007] (1) Phenyldipyrromethane derivatives (with the target functional group on the benzene ring) react with formaldehyde to generate 5,15-diphenylporphyrin;
[0008] (2) reacting the 5,15-diphenylporphyrin obtained in step (1) with phenyllithium at low temperature to obtain 5,10,15-triphenylporphyrin;
[0009] (3) dissolving the 5,10,15-triphenylporphyrin obtained in step (2) and pyridine in chloroform, and then adding N-bromosuccinimide to react to obtain 5-bromo-10,15,20-triphenylporphyrin;
[0010] (4) reacting the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) with a metal salt (M1) to obtain 5-bromo-10,15,20-triphenylporphyrin M1;
[0011] (5) reacting the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) with a metal salt (M2) to obtain 5-bromo-10,15,20-triphenylporphyrin M2;
[0012] When the metal salt (M1) used in step (4) is the same as the metal salt (M2) used in step (5), 5-bromo-10,15,20-triphenylporphyrin M1 is the same as 5-bromo-10,15,20-triphenylporphyrin M2; step (5) is omitted;
[0013] (6) reacting the 5-bromo-10,15,20-triphenylporphyrin M2 obtained in step (5) with pinacol borane to obtain 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin M2;
[0014] (7) reacting the 5-bromo-10,15,20-triphenylporphyrin M1 obtained in step (4) and the 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin M2 obtained in step (6) with cesium carbonate in the presence of a catalyst to generate a bimetallic porphyrin;
[0015] (8) The bimetallic porphyrin is loaded on a carrier by a simple impregnation method, and then carbonized at high temperature to obtain the porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene.
[0016] Furthermore, the specific operation of step (1) is as follows: dissolving a phenyldipyrromethane derivative (having a target functional group on its benzene ring) and formaldehyde in chloroform, purging the mixture with argon for 10 minutes to remove dissolved oxygen, then adding boron trifluoride ether complex to the reaction mixture, and stirring in the dark for 18 hours; then, first adding triethylamine to the reaction mixture, and then adding 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and stirring the mixture for 1 hour; thereafter, concentrating the crude mixture under reduced pressure, eluting and filtering the crude mixture with dichloromethane, and thoroughly washing with methanol to obtain the product 5,15-diphenylporphyrin; the molar ratio of the phenyldipyrromethane derivative to formaldehyde is 2:2.03.
[0017] Furthermore, the specific operation of step (2) is as follows: dissolving the 5,15-diphenylporphyrin and phenyllithium obtained in step (1) in tetrahydrofuran, and then placing the mixture at -78°C, the mixture turns dark red, and is stirred at -78°C for 2 hours; allowing the temperature to rise to room temperature, adding 0°C H2O to the reaction mixture, and stirring for 10 minutes; subsequently, adding 2,3-dichloro-5,6-dicyano-1,4-benzoquinone to the reaction mixture, the green mixture turns dark red, and stirring is continued for another 30 minutes; pouring the reaction mixture into brine, extracting with dichloromethane, and then purifying the product to obtain 5,10,15-triphenylporphyrin; the molar ratio of the 5,15-diphenylporphyrin to the phenyllithium is 1:7.5.
[0018] Furthermore, the specific operation of step (3) is as follows: at 0°C, dissolving the 5,10,15-triphenylporphyrin and pyridine obtained in step (2) in chloroform, adding N-bromosuccinimide to the mixture, monitoring the reaction by TLC, adding acetone to the mixture after 20 minutes, washing the mixture with water, drying the mixture with Na2SO4, evaporating the solvent, purifying the product, and obtaining 5-bromo-10,15,20-triphenylporphyrin; the molar ratio of the 5,10,15-triphenylporphyrin, pyridine and N-bromosuccinimide is 1:4:1.4.
[0019] Furthermore, the specific operation of step (4) is: heating the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) and the metal salt (M1) to 200° C. under nitrogen conditions for reaction for 3 hours, stopping the reaction and cooling to room temperature, purifying the product, and obtaining 5-bromo-10,15,20-triphenylporphyrin M1.
[0020] Furthermore, the specific operation of step (5) is: heating the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) and the metal salt (M2) to 200° C. under nitrogen conditions for reaction for 3 hours, stopping the reaction and cooling to room temperature, purifying the product to obtain 5-bromo-10,15,20-triphenylporphyrin M2;
[0021] When the metal salt (M1) used in step (4) is the same as the metal salt (M2) used in step (5), 5-bromo-10,15,20-triphenylporphyrin M1 is the same as 5-bromo-10,15,20-triphenylporphyrin M2; step (5) is omitted.
[0022] Furthermore, the specific operation of step (6) is: dissolving the 5-bromo-10,15,20-triphenylporphyrin M2 obtained in step (5) in ultra-dry 1,2-dichloroethane and ultra-dry triethylamine, adding pinacol borane and dichlorobis(triphenylphosphine)palladium(II) to the mixture, stirring the mixture at 75° C., monitoring the reaction by TLC, purifying the product, and obtaining 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin M2; the molar ratio of the 5-bromo-10,15,20-triphenylporphyrin M2 to pinacol borane is 1:20.
[0023] Furthermore, the metal salt (M1) in step (4) is one of platinum chloride, palladium chloride, manganese chloride, gold chloride, silver chloride, cupric acetate, ferrous chloride, nickel acetate, and cobalt acetate; the metal salt (M2) in step (5) is one of platinum chloride, palladium chloride, manganese chloride, gold chloride, silver chloride, cupric acetate, ferrous chloride, nickel acetate, and cobalt acetate; the carrier in step (7) is activated carbon, chitosan, ZIF-8, ZIF-67, molecular sieve, carbon nanotube or graphene; the loading amount of the bimetallic porphyrin in step (8) is 0.5wt%.
[0024] The second technical solution provided by the present invention is to use the porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene prepared by the above-mentioned preparation method for selective hydrogenation of acetylene to prepare ethylene, use a fixed bed as a reactor, add the porphyrin-based diatomic catalyst for acetylene hydrogenation to prepare ethylene into a quartz tube supporting the fixed bed, and carry out selective hydrogenation of acetylene to prepare ethylene at normal pressure and 140° C. in an atmosphere of acetylene, ethylene and hydrogen.
[0025] Furthermore, the atmosphere is 0.99% acetylene, 50% ethylene and 10% hydrogen in volume percentage, with argon as the balance gas.
[0026] The present invention first designs and synthesizes a single porphyrin module, then complexes metal ions in the porphyrin cavity, realizes the connection of the porphyrin modules and the adjustment of the metal spacing and geometric configuration through an intermediate connecting unit, obtains a bimetallic porphyrin, and then loads it on a suitable carrier, and further undergoes high-temperature carbonization to obtain a diatomic catalyst; the porphyrin-based diatomic catalyst of the present invention is used in the selective hydrogenation of acetylene to prepare ethylene, thereby realizing the efficient generation of ethylene, significantly improving the hydrogenation stability of the catalyst, and having high ethylene yield, high selectivity and high stability.
[0027] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:
[0028] (1) Compared with metal salts, porphyrin has the advantages of uniform dispersion and good catalytic performance.
[0029] (2) Diatom catalysts have the advantages of higher loading and more flexible active sites than single-atom catalysts.
[0030] (3) Synergistic catalysis between two metal atoms. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 It is a schematic diagram of the preparation route of the present invention.
[0032] Figure 2 This is the AC HAADFSTEM image of the Pt2 / NC homonuclear diatomic spherical aberration corrected transmission electron microscope; the circles mark the diatomic metal pairs, and three typical positions are selected and their distances are measured.
[0033] Figure 3 This is the AC HAADFSTEM image of the Pd1-Fe1 / NC heteronuclear diatomic spherical aberration corrected transmission electron microscope; the circles mark the diatomic metal pairs, and three typical positions are selected and their distances are measured. DETAILED DESCRIPTION
[0034] The present invention is further described below in conjunction with embodiments, but the protection scope of the present invention is not limited to the scope represented by the embodiments.
[0035] Example 1 Preparation of Pt2 / NC diatomic catalyst
[0036] This embodiment provides a method for preparing a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene, and the specific steps are:
[0037] (1) Synthesis of 5,15-diphenylporphyrin: Phenyldipyrrolmethane derivative (whose functional group on the benzene ring is -H) (20 mmol) and formaldehyde (20.3 mmol) were dissolved in 500 mL of chloroform solvent, and the mixture was purged with argon for 10 min to remove dissolved oxygen. Boron trifluoride ether complex (11.9 mmol) was then added to the reaction mixture, and stirred in a dark environment for 18 h. Then triethylamine (30 mL) was first added to the reaction mixture, followed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (23.8 mmol), and the mixture was stirred for 1 h. Thereafter, the crude mixture was concentrated under reduced pressure, filtered with dichloromethane, and thoroughly washed with methanol to obtain the product 5,15-diphenylporphyrin.
[0038] (2) Synthesis of 5,10,15-triphenylporphyrin: 5,15-diphenylporphyrin (0.032 mmol) and phenyllithium (0.24 mmol) obtained in step (1) were dissolved in tetrahydrofuran (1.3 mL), and the mixture was then injected into a dry flask at -78°C using a syringe. The mixture turned dark red and was stirred at -78°C for 2 h. The cooling bath was removed, the temperature was raised to room temperature, 0°C H2O was added to the reaction mixture, and the mixture was stirred for 10 min. Subsequently, DDQ was added to the reaction mixture, the green mixture turned dark red, and the mixture was stirred for another 30 min. The reaction mixture was poured into brine, extracted with dichloromethane, and the product was purified by column chromatography to obtain 5,10,15-triphenylporphyrin.
[0039] (3) Synthesis of 5-bromo-10,15,20-triphenylporphyrin: 5,10,15-triphenylporphyrin (1.4 mmol) obtained in step (2) and pyridine (5.6 mmol) were dissolved in CHCl3 (300 mL) at 0°C, and N-bromosuccinimide (1.96 mmol) was added to the mixture. The disappearance of the starting porphyrin was monitored by TLC. After 20 min, acetone (15 mL) was added to the mixture, and the mixture was washed with water. The mixture was dried over Na2SO4, the solvent was evaporated, and the product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin.
[0040] (4) Synthesis of 5-bromo-10,15,20-triphenylporphyrin platinum: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) and platinum chloride (1 mmol) obtained in step (3) were dissolved in diphenyl ether (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 200° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the product was diluted with 200 mL of n-hexane. The product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin platinum.
[0041] (5) Synthesis of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin platinum: 5-bromo-10,15,20-triphenylporphyrin platinum (0.36 mmol) obtained in step (4) was dissolved in ultra-dry 1,2-dichloroethane (23 mL) and ultra-dry triethylamine (0.7 mL). Pinacolatoborane (7.2 mmol) and dichlorobis(triphenylphosphine)palladium(II) were added to the mixture. The mixture was stirred at 75° C. The reaction was monitored by TLC. The product was purified by column chromatography to obtain 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin platinum.
[0042] (6) Synthesis of bimetallic porphyrin Pt-Pt: 5-bromo-10,15,20-triphenylporphyrin platinum (0.137 mmol) obtained from step (4) and 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin platinum (0.137 mmol) obtained from step (5) were placed in a Schlenk tube with Cs2CO3 (0.301 mmol), and the reactants were dried under high vacuum. Ultra-dry dimethylformamide (DMF) (3 mL) and ultra-dry toluene (12 mL) were added to the mixture, and the mixture was degassed by three freeze-pump-thaw cycles. To the mixture was added Pd(PPh3)4 (0.021 mmol), the flask was sealed, the mixture was stirred at 80°C, the reaction was monitored by TLC, the reaction was quenched with water, extracted with dichloromethane, and the product was purified by column chromatography.
[0043] (7) The bimetallic porphyrin Pt-Pt (loading amount 0.5 wt%) and activated carbon carrier (2 g) obtained in step (6) were dissolved in ethanol (40 mL), magnetically stirred at room temperature for 12 h, and ethanol was evaporated under reduced pressure to obtain a solid mixture. The obtained solid mixture was placed in a tube furnace, raised to 400°C at a rate of 10°C / min, maintained for 2 h, and cooled to room temperature to obtain a Pt2 / NC diatomic catalyst. Catalyst characterization is shown in Figure 2 .
[0044] Example 2 Preparation of Pd1-Fe1 / NC diatomic catalyst
[0045] This embodiment 2 provides a method for preparing a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene, and the specific steps are:
[0046] (1) The synthesis of 5,15-diphenylporphyrin is the same as step (1) of Example 1.
[0047] (2) The synthesis of 5,10,15-triphenylporphyrin is the same as step (2) of Example 1.
[0048] (3) The synthesis of 5-bromo-10,15,20-triphenylporphyrin is the same as step (3) of Example 1.
[0049] (4) Synthesis of 5-bromo-10,15,20-triphenylporphyrin palladium: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) and palladium chloride (1 mmol) obtained in step (3) were dissolved in N,N-dimethylformamide (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 150° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the solid was filtered out by suction. The product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin palladium.
[0050] (5) Synthesis of 5-bromo-10,15,20-triphenylporphyrin iron: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) obtained in step (3) and ferrous chloride (1 mmol) were dissolved in N,N-dimethylformamide (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 150° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the solid was filtered out by suction. The product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin iron.
[0051] (6) Synthesis of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin iron: 5-bromo-10,15,20-triphenylporphyrin iron (0.36 mmol) obtained in step (5) was dissolved in ultra-dry 1,2-dichloroethane (23 mL) and ultra-dry triethylamine (0.7 mL). Pinacolatoborane (7.2 mmol) and dichlorobis(triphenylphosphine)palladium(II) were added to the mixture. The mixture was stirred at 75° C. The reaction was monitored by TLC. The product was purified by column chromatography to obtain 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin iron.
[0052] (7) Synthesis of bimetallic porphyrin Pd-Fe: 5-bromo-10,15,20-triphenylporphyrin palladium (0.137 mmol) obtained from step (4) and 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin iron (0.137 mmol) obtained from step (6) were placed in a Schlenk tube with Cs2CO3 (0.301 mmol), and the reactants were dried under high vacuum. Ultra-dry DMF (3 mL) and ultra-dry toluene (12 mL) were added to the mixture, and the mixture was degassed by three freeze-pump-thaw cycles. Pd(PPh3)4 (0.021 mmol) was added to the mixture, the flask was sealed, the mixture was stirred at 80°C, the reaction was monitored by TLC, the reaction was quenched with water, extracted with dichloromethane, and the product was purified by column chromatography.
[0053] (8) The bimetallic porphyrin Pd-Fe (loading amount 0.5 wt%) obtained in step (7) and the activated carbon carrier (2 g) were dissolved in ethanol (40 mL), magnetically stirred at room temperature for 12 h, and ethanol was evaporated under reduced pressure to obtain a solid mixture. The obtained solid mixture was placed in a tube furnace, raised to 400°C at a rate of 10°C / min, maintained for 2 h, and cooled to room temperature to obtain a Pd1-Fe1 / NC diatomic catalyst. Catalyst characterization is shown in Figure 3 .
[0054] Example 3 Preparation of Pd1-Cu1 / NC diatomic catalyst
[0055] This embodiment provides a method for preparing a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene, and the specific steps are:
[0056] (1) The synthesis of 5,15-diphenylporphyrin is the same as step (1) of Example 1.
[0057] (2) The synthesis of 5,10,15-triphenylporphyrin is the same as step (2) of Example 1.
[0058] (3) The synthesis of 5-bromo-10,15,20-triphenylporphyrin is the same as step (3) of Example 1.
[0059] (4) Synthesis of 5-bromo-10,15,20-triphenylporphyrin palladium: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) and palladium chloride (1 mmol) obtained in step (3) were dissolved in DMF (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 150° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the solid was diluted with 150 ml of water to precipitate. The solid was filtered and the product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin palladium.
[0060] (5) Synthesis of 5-bromo-10,15,20-triphenylporphyrin copper: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) obtained in step (3) and copper acetate (1 mmol) were dissolved in DMF (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 150° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the solid was diluted with 150 ml of water to precipitate. The solid was filtered and the product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin copper.
[0061] (6) Synthesis of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin copper: 5-bromo-10,15,20-triphenylporphyrin copper (0.36 mmol) obtained in step (5) was dissolved in ultra-dry 1,2-dichloroethane (23 mL) and ultra-dry triethylamine (0.7 mL). Pinacol borane (7.2 mmol) and dichlorobis(triphenylphosphine)palladium(II) were added to the mixture. The mixture was stirred at 75° C. The reaction was monitored by TLC. The product was purified by column chromatography to obtain 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin copper.
[0062] (7) Synthesis of bimetallic porphyrin Pd-Cu: 5-bromo-10,15,20-triphenylporphyrin palladium (0.137 mmol) obtained from step (4) and 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin copper (0.137 mmol) obtained from step (6) were placed in a Schlenk tube with Cs2CO3 (0.301 mmol), and the reactants were dried under high vacuum. Ultra-dry DMF (3 mL) and ultra-dry toluene (12 mL) were added to the mixture, and the mixture was degassed by three freeze-pump-thaw cycles. Pd(PPh3)4 (0.021 mmol) was added to the mixture, the flask was sealed, the mixture was stirred at 80°C, the reaction was monitored by TLC, the reaction was quenched with water, extracted with dichloromethane, and the product was purified by column chromatography.
[0063] (8) The bimetallic porphyrin Pd-Cu (loading amount 0.5wt%) obtained in step (7) and the activated carbon carrier (2g) were dissolved in ethanol (40mL), magnetically stirred at room temperature for 12h, and the ethanol was evaporated under reduced pressure to obtain a solid mixture. The obtained solid mixture was placed in a tube furnace, raised to 400°C at a rate of 10°C / min, maintained for 2h, cooled to room temperature, and the catalyst was taken out to obtain a Pd1-Cu1 / NC diatomic catalyst.
[0064] Example 4 Preparation of Fe1-Co1 / NC diatomic catalyst
[0065] This embodiment provides a method for preparing a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene, and the specific steps are:
[0066] (1) The synthesis of 5,15-diphenylporphyrin is the same as step (1) of Example 1.
[0067] (2) The synthesis of 5,10,15-triphenylporphyrin is the same as step (2) of Example 1.
[0068] (3) The synthesis of 5-bromo-10,15,20-triphenylporphyrin is the same as step (3) of Example 1.
[0069] (4) Synthesis of 5-bromo-10,15,20-triphenylporphyrin iron: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) and ferrous chloride (1 mmol) obtained in step (3) were dissolved in DMF (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 150° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the solid was diluted with 150 mL of water to precipitate. The solid was filtered and the product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin iron.
[0070] (5) Synthesis of 5-bromo-10,15,20-triphenylporphyrin cobalt: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) and cobalt acetate (1 mmol) obtained in step (3) were dissolved in DMF (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 150° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the solid was diluted with 150 mL of water to precipitate. The solid was filtered and the product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin cobalt.
[0071] (6) Synthesis of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin cobalt: 5-bromo-10,15,20-triphenylporphyrin cobalt (0.36 mmol) obtained in step (5) was dissolved in ultra-dry 1,2-dichloroethane (23 mL) and ultra-dry triethylamine (0.7 mL), and pinacol borane (7.2 mmol) and dichlorobis(triphenylphosphine)palladium(II) were added to the mixture. The mixture was stirred at 75° C. The reaction was monitored by TLC, and the product was purified by column chromatography to obtain 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin cobalt.
[0072] (7) Synthesis of bimetallic porphyrin Fe-Co: 5-bromo-10,15,20-triphenylporphyrin iron (0.137 mmol) obtained from step (4) and 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin cobalt (0.137 mmol) obtained from step (6) were placed in a Schlenk tube with Cs2CO3 (0.301 mmol), and the reactants were dried under high vacuum. Ultra-dry DMF (3 mL) and ultra-dry toluene (12 mL) were added to the mixture, and the mixture was degassed by three freeze-pump-thaw cycles. Pd(PPh3)4 (0.021 mmol) was added to the mixture, the flask was sealed, the mixture was stirred at 80°C, the reaction was monitored by TLC, the reaction was quenched with water, extracted with dichloromethane, and the product was purified by column chromatography.
[0073] (8) The bimetallic porphyrin Fe-Co (loading amount 0.5 wt%) obtained in step (7) and the activated carbon carrier (2 g) were dissolved in ethanol (40 mL), magnetically stirred at room temperature for 12 h, and ethanol was evaporated under reduced pressure to obtain a solid mixture. The obtained solid mixture was placed in a tube furnace, raised to 400° C. at a rate of 10° C. / min, maintained for 2 h, and after cooling to room temperature, the catalyst was taken out to obtain a Fe1-Co1 / NC diatomic catalyst.
[0074] Example 5 Preparation of Ni2 / NC diatomic catalyst
[0075] This embodiment provides a method for preparing a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene, and the specific steps are:
[0076] (1) The synthesis of 5,15-diphenylporphyrin is the same as step (1) of Example 1.
[0077] (2) The synthesis of 5,10,15-triphenylporphyrin is the same as step (2) of Example 1.
[0078] (3) The synthesis of 5-bromo-10,15,20-triphenylporphyrin is the same as step (3) of Example 1.
[0079] (4) Synthesis of 5-bromo-10,15,20-triphenylporphyrin nickel: 5-bromo-10,15,20-triphenylporphyrin (0.2 mmol) obtained in step (3) and nickel acetate (1 mmol) were dissolved in N,N-dimethylformamide (40 mL), and the interior was filled with nitrogen by venting; the reaction was stirred at 150° C. for 3 h with a magnetic stirrer, the reaction was stopped and cooled to room temperature, and the solid was filtered out by suction. The product was purified by column chromatography to obtain 5-bromo-10,15,20-triphenylporphyrin nickel.
[0080] (5) Synthesis of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin nickel: 5-bromo-10,15,20-triphenylporphyrin nickel (0.36 mmol) obtained in step (4) was dissolved in ultra-dry 1,2-dichloroethane (23 mL) and ultra-dry triethylamine (0.7 mL). Pinacolatoborane (7.2 mmol) and dichlorobis(triphenylphosphine)palladium(II) were added to the mixture. The mixture was stirred at 75° C. The reaction was monitored by TLC. The product was purified by column chromatography to obtain 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin nickel.
[0081] (6) Synthesis of bimetallic porphyrin Ni-Ni: 5-bromo-10,15,20-triphenyl porphyrin nickel (0.137 mmol) obtained from step (4) and 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) porphyrin nickel (0.137 mmol) obtained from step (5) were placed in a Schlenk tube with Cs2CO3 (0.301 mmol), and the reactants were dried under high vacuum. Ultra-dry DMF (3 mL) and ultra-dry toluene (12 mL) were added to the mixture, and the mixture was degassed by three freeze-pump-thaw cycles. Pd(PPh3)4 (0.021 mmol) was added to the mixture, the flask was sealed, the mixture was stirred at 80°C, the reaction was monitored by TLC, the reaction was quenched with water, extracted with dichloromethane, and the product was purified by column chromatography.
[0082] (7) The bimetallic porphyrin Ni-Ni (loading amount 0.5 wt%) obtained in step (6) and the activated carbon carrier (2 g) were dissolved in ethanol (40 mL), magnetically stirred at room temperature for 12 h, and ethanol was evaporated under reduced pressure to obtain a solid mixture. The obtained solid mixture was placed in a tube furnace, raised to 400° C. at a rate of 10° C. / min, maintained for 2 h, and after cooling to room temperature, the catalyst was taken out to obtain a Ni2 / NC diatomic catalyst.
[0083] The activity of a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene prepared in an embodiment of the present invention is expressed in terms of acetylene conversion and ethylene selectivity. The acetylene conversion and ethylene selectivity are calculated according to the following formula.
[0084] The calculation method of acetylene conversion is:
[0085]
[0086] The ethylene selectivity is calculated as:
[0087]
[0088] The porphyrin-based diatomic catalyst prepared in Example 1-5 was applied to the selective hydrogenation of acetylene to prepare ethylene. 100 mg of the catalyst was weighed and mixed with 900 mg of quartz sand in a 6 mm inner diameter quartz tube equipped with a fixed bed. The mixture was reduced at 200°C with 10% hydrogen for 1 h, and naturally cooled to room temperature. Then, 0.99% acetylene, 50% ethylene and 10% hydrogen by volume were used as reactants, and argon was used as the balance gas. The mixture was heated at 140°C, normal pressure, and a weight hourly space velocity of 6000 h -1The reaction was carried out under the conditions of , and the gas after the reaction was monitored in real time by gas chromatography to analyze the acetylene conversion rate and ethylene selectivity. The results obtained are as follows: the conversion rate of acetylene by Pt2 / NC diatomic catalyst is 99.3%, and the selectivity of ethylene is 96.4%; the conversion rate of acetylene by Pd1-Fe1 / NC diatomic catalyst is 98.6%, and the selectivity of ethylene is 95.2%; the conversion rate of acetylene by Pd1-Cu1 / NC diatomic catalyst is 98.2%, and the selectivity of ethylene is 94.3%; the conversion rate of acetylene by Fe1-Co1 / NC diatomic catalyst is 93.7%, and the selectivity of ethylene is 91.5%; the conversion rate of acetylene by Ni2 / NC diatomic catalyst is 93.2%, and the selectivity of ethylene is 90.6%; and the acetylene conversion rate and ethylene selectivity of the porphyrin-based diatomic catalyst prepared in Examples 1-5 maintained good stability after five cycles.
Claims
1. A method for preparing a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene, characterized in that: The following steps are involved: (1) a phenyl dipyrromethane derivative and formaldehyde react to generate 5,15-diphenylporphyrin; the phenyl dipyrromethane derivative has a target functional group on its benzene ring; (2) reacting the 5,15-diphenylporphyrin obtained in step (1) with phenyllithium at low temperature to obtain 5,10,15-triphenylporphyrin; (3) dissolving the 5,10,15-triphenylporphyrin obtained in step (2) and pyridine in chloroform, and then adding N-bromosuccinimide to react to obtain 5-bromo-10,15,20-triphenylporphyrin; (4) reacting the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) with a metal salt (M1) to obtain 5-bromo-10,15,20-triphenylporphyrin M1; (5) reacting the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) with a metal salt (M2) to obtain 5-bromo-10,15,20-triphenylporphyrin M2; When the metal salt (M1) used in step (4) is the same as the metal salt (M2) used in step (5), 5-bromo-10,15,20-triphenylporphyrin M1 is the same as 5-bromo-10,15,20-triphenylporphyrin M2; step (5) is omitted; (6) reacting the 5-bromo-10,15,20-triphenylporphyrin M2 obtained in step (5) with pinacol borane to obtain 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin M2; (7) reacting the 5-bromo-10,15,20-triphenylporphyrin M1 obtained in step (4) and the 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin M2 obtained in step (6) with cesium carbonate in the presence of a catalyst to generate a bimetallic porphyrin; (8) The bimetallic porphyrin is loaded on a carrier by a simple impregnation method, and then carbonized at high temperature to obtain the porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene.
2. A method for preparing a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene according to claim 1, characterized in that: The specific operation of step (1) is as follows: dissolving a phenyldipyrromethane derivative and formaldehyde in chloroform, purging the mixture with argon for 10 minutes to remove dissolved oxygen, then adding boron trifluoride ether complex to the reaction mixture, and stirring in the dark for 18 hours; then, first adding triethylamine to the reaction mixture, then adding 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, and stirring the mixture for 1 hour; thereafter, concentrating the crude mixture under reduced pressure, eluting and filtering the crude mixture with dichloromethane, and thoroughly washing with methanol to obtain the product 5,15-diphenylporphyrin; the molar ratio of the phenyldipyrromethane derivative to formaldehyde is 2:2.
03.
3. The method for preparing a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene according to claim 1, characterized in that: The specific operation of step (2) is as follows: dissolving the 5,15-diphenylporphyrin and phenyllithium obtained in step (1) in tetrahydrofuran, and then placing the mixture at -78°C, the mixture turns dark red, and stirring at -78°C for 2 hours; allowing the temperature to rise to room temperature, adding 0°C H2O to the reaction mixture, and stirring for 10 minutes; subsequently, adding 2,3-dichloro-5,6-dicyano-1,4-benzoquinone to the reaction mixture, the green mixture turns dark red, and stirring is continued for another 30 minutes; pouring the reaction mixture into brine, extracting with dichloromethane, and then purifying the product to obtain 5,10,15-triphenylporphyrin; the molar ratio of the 5,15-diphenylporphyrin to the phenyllithium is 1:7.
5.
4. The method for preparing a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene according to claim 1, characterized in that: The specific operation of step (3) is as follows: at 0° C., dissolving the 5,10,15-triphenylporphyrin and pyridine obtained in step (2) in chloroform, adding N-bromosuccinimide to the mixture, monitoring the reaction by TLC, adding acetone to the mixture after 20 minutes, washing the mixture with water, drying the mixture with Na2SO4, evaporating the solvent, purifying the product, and obtaining 5-bromo-10,15,20-triphenylporphyrin; the molar ratio of the 5,10,15-triphenylporphyrin, pyridine and N-bromosuccinimide is 1:4:1.
4.
5. The method for preparing a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene according to claim 1, characterized in that: The specific operation of step (4) is as follows: the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) and the metal salt (M1) are heated to 200° C. under nitrogen conditions for reaction for 3 hours, the reaction is stopped and cooled to room temperature, and the product is purified to obtain 5-bromo-10,15,20-triphenylporphyrin M1.
6. The method for preparing a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene according to claim 1, characterized in that: The specific operation of step (5) is as follows: heating the 5-bromo-10,15,20-triphenylporphyrin obtained in step (3) and the metal salt (M2) to 200° C. under nitrogen for 3 h, stopping the reaction and cooling to room temperature, purifying the product, and obtaining 5-bromo-10,15,20-triphenylporphyrin M2; When the metal salt (M1) used in step (4) is the same as the metal salt (M2) used in step (5), 5-bromo-10,15,20-triphenylporphyrin M1 is the same as 5-bromo-10,15,20-triphenylporphyrin M2; step (5) is omitted.
7. The method for preparing a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene according to claim 1, characterized in that: The specific operation of step (6) is as follows: dissolving the 5-bromo-10,15,20-triphenylporphyrin M2 obtained in step (5) in ultra-dry 1,2-dichloroethane and ultra-dry triethylamine, adding pinacol borane and dichlorobis(triphenylphosphine)palladium(II) to the mixture, stirring the mixture at 75° C., monitoring the reaction by TLC, purifying the product, and obtaining 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin M2; the molar ratio of the 5-bromo-10,15,20-triphenylporphyrin M2 to the pinacol borane is 1:
20.
8. The method for preparing a porphyrin-based diatomic catalyst for acetylene hydrogenation to ethylene according to claim 1, characterized in that: The metal salt (M1) in step (4) is one of platinum chloride, palladium chloride, manganese chloride, gold chloride, silver chloride, cupric acetate, ferrous chloride, nickel acetate, and cobalt acetate; the metal salt (M2) in step (5) is one of platinum chloride, palladium chloride, manganese chloride, gold chloride, silver chloride, cupric acetate, ferrous chloride, nickel acetate, and cobalt acetate; the carrier in step (7) is activated carbon, chitosan, ZIF-8, ZIF-67, molecular sieve, carbon nanotube or graphene; the loading amount of the bimetallic porphyrin in step (8) is 0.5wt%.
9. A porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.
10. Use of a porphyrin-based diatomic catalyst for hydrogenating acetylene to ethylene prepared by the preparation method according to any one of claims 1 to 8, characterized in that: For the selective hydrogenation of acetylene to prepare ethylene, a fixed bed is used as a reactor, the porphyrin-based diatomic catalyst for the hydrogenation of acetylene to prepare ethylene is added into a quartz tube matched with the fixed bed, and the selective hydrogenation of acetylene to prepare ethylene is carried out at normal pressure and 140° C. in an atmosphere of acetylene, ethylene and hydrogen; the atmosphere is 0.99% acetylene, 50% ethylene and 10% hydrogen by volume, and argon is used as the balance gas.