A continuous microfluidic channel synthesis method for a hydrogen production catalyst

Abstract

The present invention relates to the technical field of hydrogen production catalysts, and discloses a continuous microchannel synthesis method for hydrogen production catalysts. The present invention uses a silicon carbide microchannel reactor and a continuous microchannel synthesis method to replace the conventional hot solvent method, and uses 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline as a ligand and cobalt ions as the central metal to prepare a novel metal-organic framework MOFs material. It has the advantages of high pore structure, large specific surface area, and many catalytic center sites, and can be better applied to the oxygen evolution reaction OER catalyst for electrolytic water hydrogen production. After electrochemical performance testing, when the current density reaches 10 mA·cm- 2 , the overpotential is only 192.4 - 241.2 mV. The Tafel slope is only 62.9 - 102.4 mV / dec. It exhibits excellent electrolytic water OER activity.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production catalysts, and specifically to a continuous microfluidic channel synthesis method for hydrogen production catalysts. Background Art

[0002] Hydrogen energy is currently the new energy with the most development potential. Electrochemically driven electrolysis of water to produce hydrogen is a research trend. Electrocatalytic water splitting to produce hydrogen plays an extremely important role in energy conversion technologies such as hydrogen fuel cells and metal-air batteries. However, the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in electrolytic water hydrogen production usually require the addition of hydrogen evolution or oxygen evolution catalysts to promote the reaction process of electrolytic water hydrogen production.

[0003] Currently, the main OER catalysts for the oxygen evolution reaction are platinum-based noble metal catalysts, metal oxide catalysts, carbon-based catalysts, etc. Metal-organic frameworks (MOFs) are a new type of inorganic porous crystalline material, which have the characteristics of high porosity, large specific surface area, adjustable framework size, etc., and have broad application prospects in electrochemistry energy catalysts. The current methods for synthesizing metal-organic frameworks are mainly hydrothermal methods, hot solvent methods, etc. The silicon carbide microchannel and continuous microfluidic channel synthesis methods have the advantages of strengthening reactions, increasing product conversion rates, facilitating precise control of the reaction process, and reducing energy consumption. In recent years, they have been well applied in the synthesis of small molecules, polymer microspheres, and metal-organic frameworks. The present invention aims to use the silicon carbide microchannel and continuous microfluidic channel synthesis methods to prepare novel metal-organic frameworks (MOFs) for use in OER catalysts for electrolytic water hydrogen production. Summary of the Invention

[0004] The technical problem solved by the present invention is: The present invention uses a continuous microfluidic channel method to synthesize a novel electrolytic water hydrogen production catalyst.

[0005] The technical solution provided by the present invention is:

[0006] A continuous microfluidic channel synthesis method for a hydrogen production catalyst: Add 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline to N,N-dimethylformamide, stir and dissolve to prepare a ligand solution, and add it to metering pump A; Add a metal compound to distilled water to prepare a metal solution, and add it to metering pump B; Set the temperature of the silicon carbide microchannel reactor to 100 - 120 °C, then set the flow rates of metering pump A and metering pump B to (1 - 1.8) L / h, and at the same time flow the ligand solution and the metal solution into the silicon carbide microchannel reactor, react for 6 - 12 h, cool and discharge the material, filter by suction, wash with ethanol, and dry to obtain the hydrogen production catalyst.

[0007] Among them, the concentration of the ligand solution is (30 - 80) g / L.

[0008] Among them, the metal solution is (40 - 105) g / L.

[0009] Among them, the metal solution and the ligand solution are of equal volume.

[0010] Among them, the metal compound is any one of cobalt chloride, cobalt nitrate or cobalt sulfate.

[0011] Among them, the preparation method of 3,8 - bis(3,5 - dibenzoic acid) - 1,10 - phenanthroline is as follows: Add 3,5 - dicarboxylphenylboronic acid, 3,8 - dibromo - 1,10 - phenanthroline, potassium carbonate, and bis(triphenylphosphine)palladium dichloride to an acetonitrile solvent. Under a nitrogen atmosphere, heat to 100 - 120 °C and react for 18 - 36 h. Distill the solution under reduced pressure, add dichloromethane and water, perform extraction and separation, concentrate the organic phase, then add hydrochloric acid to adjust the pH to 3 - 4 in water, filter the precipitate by suction, wash with distilled water, and dry to obtain 3,8 - bis(3,5 - dibenzoic acid) - 1,10 - phenanthroline.

[0012] Among them, the mass of 3,5 - dicarboxylphenylboronic acid is 120 - 135% of the mass of 3,8 - dibromo - 1,10 - phenanthroline.

[0013] The technical effects produced by the present invention are as follows: The present invention uses 3,5 - dicarboxylphenylboronic acid and 3,8 - dibromo - 1,10 - phenanthroline to carry out a coupling reaction to prepare a novel multidentate ligand 3,8 - bis(3,5 - dibenzoic acid) - 1,10 - phenanthroline, which contains 1,10 - phenanthroline and multiple carboxyl groups and can have a strong multidentate coordination effect with cobalt ions.

[0014] The present invention uses a silicon carbide microchannel reactor and a continuous microfluidic channel synthesis method to replace the conventional hot solvent method. Using 3,8 - bis(3,5 - dibenzoic acid) - 1,10 - phenanthroline as a ligand and cobalt ions as the central metal, a novel metal - organic framework MOFs material is prepared. Through the size effect of the silicon carbide microchannel and the precise regulation of the continuous microfluidic channel, the coordination reaction process is promoted, the reaction time is shortened, which is beneficial to improving the conversion efficiency of the product and reducing the reaction energy consumption. The prepared metal - organic framework MOFs material has the advantages of a high pore structure, a large specific surface area, and many catalytic center sites, and can be better applied to the oxygen evolution reaction OER catalyst for electrolytic water hydrogen production. After electrochemical performance testing, when the current density reaches 10 mA·cm - 2 ², the overpotential is only 192.4 - 241.2 mV. The Tafel slope is only 62.9 - 102.4 mV / dec. It shows excellent electrolytic water OER activity. Specific Embodiments

[0015] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0016] Example 1

[0017] (1) Add 5.2 g of 3,5-dicarboxylphenylboronic acid, 4 g of 3,8-dibromo-1,10-phenanthroline, 14.8 g of potassium carbonate, and 0.9 g of bis(triphenylphosphine)palladium dichloride to 80 mL of acetonitrile solvent. Under a nitrogen atmosphere, heat the mixture to 110 °C and react for 18 h. Distill the solution under reduced pressure, add dichloromethane and water, extract and separate, concentrate the organic phase, then add hydrochloric acid to water to adjust the pH to 3, filter the precipitate by suction, wash with distilled water, and dry to obtain 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline. The reaction formula is as follows:

[0018]

[0019] (2) Add 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline to N,N-dimethylformamide, stir to dissolve, prepare a 100 mL ligand solution with a concentration of 30 g / L, and add it to metering pump A; add cobalt nitrate to distilled water, prepare a 100 mL metal solution with a concentration of 40 g / L, and add it to metering pump B; set the temperature of the silicon carbide microchannel reactor to 100 °C, then set the flow rates of metering pump A and metering pump B to 1.4 L / h, and at the same time flow the ligand solution and the metal solution into the silicon carbide microchannel reactor, react for 12 h, cool and discharge, filter by suction, wash with ethanol, and dry to obtain a hydrogen production catalyst.

[0020] Example 2

[0021] (1) Add 5.4 g of 3,5-dicarboxylphenylboronic acid, 4 g of 3,8-dibromo-1,10-phenanthroline, 13.5 g of potassium carbonate, and 1.1 g of bis(triphenylphosphine)palladium dichloride to 100 mL of acetonitrile solvent. Under a nitrogen atmosphere, heat the mixture to 120 °C and react for 24 h. Distill the solution under reduced pressure, add dichloromethane and water, extract and separate, concentrate the organic phase, then add hydrochloric acid to water to adjust the pH to 4, filter the precipitate by suction, wash with distilled water, and dry to obtain 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline.

[0022] (2) Add 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline to N,N-dimethylformamide, stir to dissolve, prepare a 100 mL ligand solution with a concentration of 80 g / L, and add it to metering pump A; add cobalt chloride to distilled water, prepare a 100 mL metal solution with a concentration of 105 g / L, and add it to metering pump B; set the temperature of the silicon carbide microchannel reactor to 120 °C, then set the flow rates of metering pump A and metering pump B to 1.8 L / h, and at the same time flow the ligand solution and the metal solution into the silicon carbide microchannel reactor, react for 6 h, cool and discharge, filter by suction, wash with ethanol, and dry to obtain a hydrogen production catalyst.

[0023] Example 3

[0024] (1) Add 4.8 g of 3,5-dicarboxylphenylboronic acid, 4 g of 3,8-dibromo-1,10-phenanthroline, 14.8 g of potassium carbonate, and 1.1 g of bis(triphenylphosphine)palladium dichloride to 100 mL of acetonitrile solvent. Under a nitrogen atmosphere, heat up to 100 °C and react for 36 h. Distill the solution under reduced pressure, add dichloromethane and water, extract and separate, concentrate the organic phase, then add hydrochloric acid to the water to adjust the pH to 4, filter the precipitate by suction, wash with distilled water, and dry to obtain 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline.

[0025] (2) Add 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline to N,N-dimethylformamide, stir to dissolve, prepare a 100 mL ligand solution with a concentration of 45 g / L, and add it to metering pump A; add cobalt sulfate to distilled water, prepare a 100 mL metal solution with a concentration of 60 g / L, and add it to metering pump B; set the temperature of the silicon carbide microchannel reactor to 120 °C, then set the flow rates of metering pump A and metering pump B to 1 L / h, and at the same time flow the ligand solution and the metal solution into the silicon carbide microchannel reactor, react for 6 h, cool and discharge, filter by suction, wash with ethanol, and dry to obtain a hydrogen production catalyst.

[0026] Example 4

[0027] (1) Add 5.4 g of 3,5-dicarboxylphenylboronic acid, 4 g of 3,8-dibromo-1,10-phenanthroline, 12.5 g of potassium carbonate, and 1 g of bis(triphenylphosphine)palladium dichloride to 100 mL of acetonitrile solvent. Under a nitrogen atmosphere, heat up to 100 °C and react for 18 h. Distill the solution under reduced pressure, add dichloromethane and water, extract and separate, concentrate the organic phase, then add hydrochloric acid to the water to adjust the pH to 4, filter the precipitate by suction, wash with distilled water, and dry to obtain 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline.

[0028] (2) Add 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline to N,N-dimethylformamide, stir to dissolve, and prepare a 100 mL ligand solution with a concentration of 60 g / L, then add it to metering pump A; add cobalt nitrate to distilled water, prepare a 100 mL metal solution with a concentration of 92 g / L, and add it to metering pump B; set the temperature of the silicon carbide microchannel reactor to 110 °C, then set the flow rates of metering pump A and metering pump B to 1.4 L / h, and at the same time flow the ligand solution and the metal solution into the silicon carbide microchannel reactor, react for 12 h, cool and discharge, filter by suction, wash with ethanol, and dry to obtain a hydrogen production catalyst.

[0029] Comparative Example 1

[0030] (1) Add 5.2 g of 3,5-dicarboxylphenylboronic acid, 4 g of 3,8-dibromo-1,10-phenanthroline, 14.8 g of potassium carbonate, and 0.9 g of bis(triphenylphosphine)palladium dichloride to 80 mL of acetonitrile solvent. Under a nitrogen atmosphere, heat to 110 °C and react for 18 h. Distill the solution under reduced pressure, add dichloromethane and water, extract and separate, concentrate the organic phase, then add hydrochloric acid to the water to adjust the pH to 3, filter the precipitate by suction, wash with distilled water, and dry to obtain 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline.

[0031] (2) Add 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline to N,N-dimethylformamide, stir to dissolve, and prepare a 100 mL ligand solution with a concentration of 30 g / L, then add it to metering pump A; add cobalt nitrate to distilled water, prepare a 100 mL metal solution with a concentration of 40 g / L, add the ligand solution and the metal solution to a hydrothermal reaction kettle, heat to 100 °C, react for 12 h, cool and discharge, filter by suction, wash with ethanol, and dry to obtain a hydrogen production catalyst.

[0032] The electrocatalytic water splitting OER activity of the hydrogen production catalyst was tested using a three-electrode system.

[0033] Add 10 mg of the hydrogen evolution catalyst and 100 μL of nafion solution to 1 mL of distilled water and 1 mL of ethanol. After mixing evenly, coat the slurry on a glassy carbon electrode and dry to make a working electrode. Use a platinum sheet electrode as the counter electrode and an Ag / AgCl electrode as the reference electrode. 1 mol / L KOH solution is used as the electrolyte. Test through an electrochemical workstation. The scanning rate is 5 mV / s.

[0034] Table 1 Electrocatalytic Water Splitting OER Activity Test of Hydrogen Production Catalysts

[0035]

[0036] The hydrogen production catalysts of metal-organic frameworks prepared by the continuous microfluidic channel method in Examples 1 to 4 reach 10 mA·cm- 2 At the current density, the overpotential is only 192.4 - 241.2 mV. The Tafel slope is only 62.9 - 102.4 mV / dec. It shows excellent electrocatalytic water splitting OER activity.

[0037] The hydrogen production catalyst prepared by the traditional thermal solvent method in Comparative Example 1 reaches 10 mA·cm- 2 At the current density, the overpotential reaches 291.6 mV. The Tafel slope reaches 121.3 mV / dec, and the electrocatalytic water splitting OER activity is poor.

[0038] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous microfluidic channel synthesis method for a hydrogen production catalyst, characterized in that: The synthesis method is as follows: add 3,8-di(3,5-dibenzoic acid)-1,10-phenanthroline to N,N-dimethylformamide, stir to dissolve, prepare a ligand solution, and add it to metering pump A; add a metal compound to distilled water to prepare a metal solution, and add it to metering pump B; set the silicon carbide microchannel reactor to a reaction temperature, then set the flow rates of metering pump A and metering pump B, and simultaneously flow the ligand solution and the metal solution into the silicon carbide microchannel reactor to react, cool and discharge, filter, wash with ethanol, and dry to obtain a hydrogen production catalyst; The concentration of the ligand solution is (30-80) g / L; The concentration of the metal solution is (40-105) g / L; The metal solution and the ligand solution are of equal volumes; The metal compound is any one of cobalt chloride, cobalt nitrate or cobalt sulfate; The flow rate of the metering pump A and the metering pump B is (1-1.8) L / h; The reaction temperature is 100-120°C and the reaction time is 6-12h.

2. The continuous microfluidic channel synthesis method of hydrogen production catalyst according to claim 1, characterized in that: The preparation method of 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline is as follows: 3,5-dicarboxyphenylboronic acid, 3,8-dibromo-1,10-phenanthroline, potassium carbonate and bistriphenylphosphine palladium dichloride are added to an acetonitrile solvent, and the reaction is carried out in a nitrogen atmosphere, the solution is distilled under reduced pressure, dichloromethane and water are added, and the organic phase is concentrated after extraction and separation, and then hydrochloric acid is added to the water to adjust the pH to 3-4, the precipitate is filtered, washed with distilled water, and dried to obtain 3,8-bis(3,5-dibenzoic acid)-1,10-phenanthroline.

3. The continuous microfluidic channel synthesis method of hydrogen production catalyst according to claim 2, characterized in that: The mass of the 3,5-dicarboxyphenylboronic acid is 120-135% of the mass of 3,8-dibromo-1,10-phenanthroline.

4. The continuous microfluidic channel synthesis method of hydrogen production catalyst according to claim 2, characterized in that: In the preparation method of 3,8-di(3,5-dibenzoic acid)-1,10-phenanthroline, the reaction temperature is 100-120° C. and the reaction time is 18-36 hours.

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