Preparation and Application of a Supported Metal Phthalocyanine Compound Electrode for Electro-Catalytic Selective Hydrogenation of Acetylene

Abstract

The present invention discloses the preparation and application of a supported metal phthalocyanine compound electrode for electrocatalytic selective hydrogenation of acetylene. The preparation method of the electrode is carried out according to the following steps: (1) Under ultrasonic conditions, the metal phthalocyanine compound and the carrier are respectively dispersed in DMF, and then the metal phthalocyanine compound solution and the carrier solution are mixed and stirred, treated with plasma, filtered, washed and dried after the treatment is completed, and the obtained catalyst and nafion solution are poured into an organic solvent and ultrasonically treated to obtain a slurry; (2) The cut electrode material is washed; (3) The slurry is evenly coated on the electrode material and irradiated with an infrared lamp until the solution is completely dried to obtain a supported metal phthalocyanine compound electrode. The present invention also provides a method for electrocatalytic selective hydrogenation of acetylene based on this electrode, which can realize the acetylene hydrogenation reaction with high activity, high selectivity and high stability under mild room temperature conditions.

Description

Technical Field

[0001] The present invention relates to a preparation method of a supported metal phthalocyanine compound electrode for electrocatalytic selective hydrogenation of acetylene and its application in electrocatalytic selective hydrogenation of acetylene to produce ethylene. Background Art

[0002] Ethylene is mainly produced by thermal cracking of naphtha and diesel. During the preparation of ethylene, acetylene impurities with a volume fraction between 0.3% and 3% will be generated. In the process of producing polyethylene from acetylene, trace impurities will poison the Ziegler-Natta catalyst. The activity and stability of the poisoned catalyst will both decline, and at the same time, the quality of the product polyethylene will also be reduced. Therefore, it is crucial to remove acetylene from the raw material gas. The removal methods include ammoniation method, solvent absorption method, low-temperature rectification method and acetylene hydrogenation method. At present, the most commonly used method to remove acetylene impurities in the ethylene-rich stream is the thermal catalytic acetylene hydrogenation method.

[0003] For thermal catalytic reactions, it is crucial to control the temperature of the catalytic reaction. Especially for highly exothermic reactions represented by the acetylene hydrogenation reaction, the failure to timely remove the reaction heat released by the catalytic reaction will affect the activity and selectivity of the catalyst. Commercial industrial catalysts are mainly noble metal palladium catalysts, and the catalytic temperature in the range of 50-80 °C is the optimal activity range. When the catalyst exceeds 85 °C, the selectivity will drop sharply. At the same time, an excessive amount of hydrogen needs to be introduced during the acetylene catalytic hydrogenation process, the conversion rate of the reactant acetylene is greater than 90%, and the selectivity of the reaction product ethylene is about 85% (M. Armbruster et al., Nat. Mater. 11, 690-693 (2012)). Researchers have conducted sufficient research on the reaction of palladium-based catalysts. There are many existing studies hoping to develop good catalysts for selective hydrogenation of acetylene. For example, CN109174177A studied an alumina-supported ionic liquid-palladium catalyst for acetylene hydrogenation reaction, which can promote the desorption of ethylene under low loading conditions and greatly improve the selectivity of ethylene. However, the thermal catalytic acetylene hydrogenation method still faces significant challenges: (1) Commercial acetylene hydrogenation catalysts require an additional heat source to ensure the stable progress of the reaction. Most of the catalysts for thermal catalytic acetylene hydrogenation reported in the literature have a reaction temperature greater than 100 °C. At the same time, some catalysts need to carry out catalytic reactions under high-pressure conditions, which requires a large amount of energy consumption. (2) Existing catalysts are mainly noble metal Pd-based catalysts, and the cost of catalyst preparation is relatively high. (3) In the laboratory and industrial production processes, the reaction often occurs under the state of excessive hydrogen, which inevitably leads to the existence of over-hydrogenation side reactions and reduces the selectivity of ethylene. (4) Over-hydrogenation phenomena will occur during the catalytic reaction process, and the reaction products contain some ethane molecules, which means that the existing catalysts still need to improve selectivity and atomic utilization rate.

[0004] Compared with traditional thermal catalytic reactions, electrocatalytic reactions have the following advantages: (1) Electrocatalytic reactions can be carried out at room temperature and pressure; (2) Electrocatalysis has higher energy utilization efficiency due to its special energy conversion method compared to the transfer and conduction of heat energy in traditional thermal catalysis; (3) Hydrogen free radicals can be generated in situ during electrocatalytic reactions to provide a hydrogen source for catalytic hydrogenation reactions. Electrocatalytic acetylene hydrogenation has been proven to be a feasible strategy, and metal phthalocyanine compounds have shown high catalytic activity in acetylene hydrogenation electrocatalytic reactions. However, metal phthalocyanine compounds tend to stack with each other, aggregate and become inactivated during the catalytic reaction. Therefore, how to improve their stability during the catalytic process is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to realize the acetylene hydrogenation reaction under mild room temperature conditions with high activity, high selectivity and high stability, the present invention provides the preparation and application of a supported metal phthalocyanine compound electrode for electrocatalytic selective acetylene hydrogenation.

[0006] The present invention specifically adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a supported metal phthalocyanine compound electrode for electrocatalytic selective hydrogenation of acetylene, which is carried out according to the following steps:

[0008] Step 1: Under ultrasonic conditions, the metal phthalocyanine compound and the carrier are dispersed in DMF (N,N-dimethylformamide) respectively, and then the metal phthalocyanine compound solution and the carrier solution are mixed and stirred, and treated with plasma. After the treatment, the solid product is filtered to obtain a solid product, and then washed and dried. The prepared catalyst and a 5% by mass nafion solution are poured into an organic solvent respectively, and ultrasonic treatment is performed to assist the solute to dissolve in the organic solvent to obtain a slurry; the carrier is mesoporous carbon, graphene, carbon nanotubes or graphyne; the mass ratio between the metal phthalocyanine compound and the carrier is (1-3 mg): (4-30 mg), and the mass volume ratio of the metal phthalocyanine compound and the 5% by mass nafion solution is (1-3 mg) / (5-20 μL);

[0009] Step 2: Wash the cut electrode material with hydrochloric acid, ethanol and deionized water;

[0010] Step 3: evenly apply the slurry obtained in step 1 to the electrode material obtained in step 2, and irradiate with an infrared lamp until the solution is completely dry to obtain a supported metal phthalocyanine compound electrode.

[0011] Preferably, the metal phthalocyanine compound powder in step 1 is selected from at least one of copper phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, zinc phthalocyanine and iron phthalocyanine.

[0012] Preferably, the organic solvent described in step one is selected from at least one of acetone, ethanol, isobutanol, ethylene glycol, n-propanol, and isopropanol.

[0013] Preferably, in step one, the mass-volume ratio between the metal phthalocyanine compound and the solvent DMF is (1 - 3 mg) / (1 - 3 mL); the mass-volume ratio between the carrier and the solvent DMF is (1 - 3 mg) / (1 - 3 mL); the mass-volume ratio between the metal phthalocyanine compound and the organic solvent is (1 - 3 mg) / (1 - 3 mL).

[0014] Preferably, in step one, the washing liquid is a mixed solvent of DMF and ethanol, and the volume ratio of DMF to ethanol is 1:1.

[0015] Preferably, in step one, the drying condition is: vacuum drying at 80 °C for 6 - 12 h.

[0016] Preferably, the plasma treatment conditions in step one are: the vacuum degree is 50 - 1000 Pa, the plasma working gas is one or a mixture of argon, nitrogen, argon, hydrogen, etc., the voltage between the electrodes is 200 - 5000 V, the distance between the electrodes is 6 - 10 mm, and the plasma treatment time is 10 - 240 minutes.

[0017] Preferably, in step one, the frequency of the ultrasonic wave used for ultrasonic treatment is 20 - 80 kHz.

[0018] Preferably, in step two, the electrode material is carbonaceous, carbon cloth, copper foam, or nickel foam.

[0019] Preferably, in step three, the power of the infrared lamp is 100 - 200 W, and the irradiation time is 10 - 30 min.

[0020] In a second aspect, the present invention provides a method for electrocatalytic selective hydrogenation of acetylene based on the above electrode, including: placing the prepared electrode as the working electrode at the cathode of an electrochemical device, setting the reaction temperature for electrocatalytic selective hydrogenation of acetylene to be carried out at a temperature of -10 - 40 °C, and introducing a raw material gas containing acetylene with a space velocity of 500 - 80000 h -1 to make it converted into ethylene through the electrocatalytic selective hydrogenation reaction of acetylene.

[0021] Preferably, the raw material gas containing acetylene is an ethylene gas containing acetylene impurities with a volume fraction between 0.3% and 3%.

[0022] In the present invention, the cathode potential of the electrochemical device can be -1.0 - -0.4 V (compared to the reversible hydrogen electrode, RHE), or the cell voltage can be between -3 and -2.3 V.

[0023] The electrochemical device described in the present invention is a fluid electrolytic cell (as shown in Figure 4 ) or an H-type electrolytic cell (as shown in Figure 3 ). The catholyte and the anolyte are separated by an anion exchange membrane, and the catholyte and the anolyte are respectively provided on both sides. The catholyte and the anolyte are preferably KOH or NaOH solutions with a concentration range between (0.5M - 3M). The anode can be nickel foam, platinum wire, platinum sheet or platinum mesh.

[0024] Compared with the prior art, the present invention has the following innovation points and advantages:

[0025] (1) In the present invention, the stability of the catalyst is improved by constructing the π-π weak interaction between the metal phthalocyanine compound and the carrier. At the same time, the introduction of the carrier greatly improves the adsorption of acetylene gas and enhances the catalytic activity.

[0026] (2) In the present invention, by using plasma, mainly relying on the "activation effect" of the active particles in the plasma, the catalyst particle size is smaller and the dispersion is more uniform. The gas electrons and active groups react with the solid surface and are resolved into new gaseous substances and separated from the surface. It can make some active atoms, free radicals and unsaturated bonds appear on the catalyst surface. These active groups react with the active particles in the plasma to generate new active groups, thereby increasing the surface energy. In summary, the plasma treatment significantly improves the catalytic activity and stability of the metal catalyst of the present invention.

[0027] (3) The preparation method of the catalyst for electrocatalytic acetylene hydrogenation in the present invention can be used for the electrocatalytic acetylene hydrogenation reaction. Compared with thermal catalytic acetylene hydrogenation, electrocatalysis can carry out the catalytic reaction in a more mild room temperature environment, reducing energy waste and improving the atomic utilization rate of the raw material gas.

[0028] (4) In the reaction raw materials of the present invention, the hydrogen atoms come from the ionization of water. The technology of in-situ synthesis of hydrogen radicals eliminates the economic costs and potential safety hazards brought by the preparation, canning, storage and transportation of hydrogen.

[0029] (5) The metal active centers used in the reaction of the present invention are mainly base metals. Compared with the noble metal palladium-based catalyst with a wide application range in thermal catalysis, it not only reduces the synthesis cost of the catalyst, but also reduces the production costs of acetylene purification and acetylene hydrogenation to produce ethylene.

[0030] (6) The selectivity of the electrocatalytic acetylene hydrogenation reaction is higher than that of the thermal catalytic acetylene hydrogenation reaction, and it can meet the requirements of the chemical industry for high-purity ethylene. Description of the Drawings

[0031] Figure 1It is the electron microscope image of copper phthalocyanine supported on carbon paper used in Example 2;

[0032] Figure 2 It is the electron microscope image of copper phthalocyanine supported on carbon paper used in Example 2;

[0033] Figure 3 It is the schematic diagram of the electrochemical fluid electrolytic cell device used in the example;

[0034] Figure 4 It is the schematic diagram of the H-type electrolytic cell electrochemical device used in the example. Detailed implementation manners

[0035] The following specific examples are used to illustrate the present invention. It is necessary to point out that the examples are only for further illustration of the present invention, but cannot be construed as a limitation on the protection scope of the present invention. The present invention is not limited in any way. Those skilled in the art can make some non-essential improvements and adjustments based on the content of the above invention.

[0036] Example 1

[0037] A method for preparing and applying a metal phthalocyanine compound electrode for electrocatalytic acetylene hydrogenation reaction, comprising the following steps:

[0038] I. Under the ultrasonic condition of 20 kHz, 3 mg of copper phthalocyanine and 15 mg of mesoporous carbon are respectively dispersed in 3 mg and 15 mg of DMF (N,N-dimethylformamide). Subsequently, the phthalocyanine compound solution and the carrier solution are mixed and stirred. Under the conditions of helium atmosphere, a vacuum degree of 100 Pa, a voltage between the plates of 1000 V, and a distance between the plates of 6 mm, the dried catalyst is treated with plasma for 60 min. After the treatment is completed, the product is filtered and washed 3 times with 18 mL of DMF and ethanol (volume ratio 1:1), and then vacuum dried at 80 °C for 6 h. Take the prepared catalyst and 12 μL of a 5% mass fraction nafion solution (DuPont D521-1100EW, the same below) and pour them into 3 mL of acetone respectively, and ultrasonically treat at 20 kHz for 1 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0039] II. Cut the electrode material carbon cloth into 1 cm × 1 cm, and wash the carbon cloth in hydrochloric acid, ethanol and deionized water respectively to remove the surface impurities.

[0040] III. Uniformly apply the slurry obtained in step I to the electrode material obtained in step II, and then place the electrode material under an infrared lamp with a power of 100 W for irradiation for 30 min to obtain the prepared supported copper phthalocyanine electrode.

[0041] Place the electrode obtained in step III in an electrochemical fluid electrolytic cell (such as Figure 4The cathode (as shown) uses a supported copper phthalocyanine electrode as the working electrode, a nickel foam as the anode, and a 1M KOH solution as the electrolyte. The electrocatalytic reaction temperature is controlled at 25°C, and the cathode potential of the electrode is controlled at -1.0V. Meanwhile, ethylene gas containing 3% by volume of acetylene impurities is introduced onto the working electrode, and the space velocity is 3000h -1 Under this condition, the highest conversion rate of acetylene is 97.1%, and the highest selectivity of ethylene is as high as 96.1%. After continuous reaction for 72h, the activity of the reaction decreases by 3.2%, and the selectivity decreases by 1.2%.

[0042] Example 2

[0043] I. Under the condition of 40kHz ultrasonic wave, 2.5mg of cobalt phthalocyanine and 25mg of graphene are respectively dispersed in 2.5mg and 25mg of DMF (N,N-dimethylformamide). Subsequently, the phthalocyanine compound solution and the carrier solution are mixed and stirred. Under the conditions of an argon atmosphere, a vacuum degree of 300Pa, a voltage between the plates of 1000V, and a distance between the plates of 8mm, the dried catalyst is treated with plasma for 60min. After the treatment is completed, the product is filtered and washed 3 times with 27.5mL of DMF and ethanol (volume ratio 1:1), and then dried in vacuum at 80°C for 12h. Take the prepared catalyst and 8μL of a 5% mass fraction nafion solution and pour them into 2.5mL of acetone respectively, and perform ultrasonic treatment at 40kHz for 2h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0044] II. Cut the electrode material carbon cloth into 5cm×5cm, and wash the carbon cloth in hydrochloric acid, ethanol, and deionized water respectively to remove the surface impurities.

[0045] III. Uniformly apply the slurry obtained in step I onto the electrode material obtained in step II, and then place the electrode material under an infrared lamp with a power of 120W for irradiation for 27min to obtain the prepared supported cobalt phthalocyanine electrode.

[0046] Place the electrode obtained in step III at the cathode of an electrochemical fluid electrolytic cell (as Figure 4 shown), use the supported cobalt phthalocyanine electrode as the working electrode, select nickel foam as the anode, use a 1.5M KOH solution as the electrolyte, control the electrocatalytic reaction temperature at 20°C, control the cathode potential of the electrode at -0.8V, and at the same time introduce ethylene gas containing 2% by volume of acetylene impurities onto the working electrode, and the space velocity is 500h -1 Under this condition, the highest conversion rate of acetylene is 98.1%, and the highest selectivity of ethylene is as high as 96.8%. After continuous reaction for 72h, the activity of the reaction decreases by 4.2%, and the selectivity decreases by 2.2%.

[0047] Example 3

[0048] 1. Under the condition of 60 kHz ultrasonic wave, 2 mg of iron phthalocyanine and 8 mg of carbon nanotubes were respectively dispersed in 2 mg and 8 mg of DMF (N, N-dimethylformamide). Subsequently, the phthalocyanine compound solution and the carrier solution were mixed and stirred. Under the conditions of helium atmosphere, a vacuum degree of 500 Pa, a voltage between the electrodes of 1000 V, and a distance between the electrodes of 8 mm, the dried catalyst was treated with plasma for 60 min. After the treatment was completed, the product was filtered and washed 3 times with 10 mL of DMF and ethanol (volume ratio 1:1), and then vacuum dried at 80 °C for 8 h. The prepared catalyst and 5 μL of 5% nafion solution by mass were respectively poured into 1.2 mL of propanol and 1.2 mL of isobutanol, and ultrasonicated at 60 kHz for 2.5 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0049] 2. The electrode material carbon cloth was cut into 2 cm × 2 cm, and the carbon cloth was washed separately with hydrochloric acid, ethanol and deionized water to remove the surface impurities.

[0050] 3. The slurry obtained in step 1 was evenly coated on the electrode material obtained in step 2, and then the electrode material was irradiated under an infrared lamp with a power of 120 W for 27 min to obtain the prepared supported iron phthalocyanine electrode.

[0051] The electrode obtained in step 3 was placed at the cathode of an electrochemical fluid electrolytic cell (as Figure 4 shown). Using the supported iron phthalocyanine electrode as the working electrode, nickel foam was selected as the anode, and 1.5 M NaOH solution was selected as the electrolyte. The temperature of the electrocatalytic reaction was controlled at -10 °C, the cathode potential of the electrode was controlled at -0.6 V, and at the same time, ethylene gas containing 1 vol% acetylene impurities was introduced onto the working electrode, with an airspeed of 500 h -1 . Under this condition, the highest conversion rate of acetylene was 90.1%, and at the same time, the highest selectivity of ethylene was as high as 83.5%. The activity of the continuous reaction decreased by 1.1% and the selectivity decreased by 0.2% after 72 h of reaction.

[0052] Example 4

[0053] 1. Under the condition of 60 kHz ultrasonic wave, 1 mg of nickel phthalocyanine and 8 mg of graphdiyne were respectively dispersed in 1 mg and 8 mg of DMF (N, N-dimethylformamide). Subsequently, the phthalocyanine compound solution and the carrier solution were mixed and stirred. Under the conditions of helium atmosphere, a vacuum degree of 500 Pa, a voltage between the plates of 1000 V, and a distance between the plates of 8 mm, the dried catalyst was treated with plasma for 60 min. After the treatment was completed, the product was filtered and washed 3 times with 10 mL of DMF and ethanol (volume ratio 1:1), and then vacuum dried at 80 °C for 12 h. The prepared catalyst and 10 μL of 5% nafion solution by mass were respectively poured into 1 mL of ethanol, and ultrasonicated at 60 kHz for 1 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0054] 2. The electrode material carbon cloth was cut into 2.5 cm × 2.5 cm, and the carbon cloth was respectively washed in hydrochloric acid, ethanol and deionized water to remove the surface impurities.

[0055] 3. The solution obtained in step 1 was evenly coated on the electrode material obtained in step 2, and then the electrode material was irradiated under an infrared lamp with a power of 180 W for 20 min to obtain the prepared supported nickel phthalocyanine electrode.

[0056] The electrode obtained in step 3 was placed in an H-type electrolytic cell electrochemical device (as Figure 3 shown), with the supported nickel phthalocyanine electrode as the working electrode, nickel foam as the anode, 3M NaOH solution as the electrolyte, the electrocatalytic reaction temperature was controlled at 10 °C, the cathode potential of the electrode was controlled at -0.6 V, and at the same time, ethylene gas containing 5 vol% acetylene impurities was introduced onto the working electrode, and the space velocity was 700 h -1 . Under this condition, the highest conversion rate of acetylene was 93.1%, and at the same time, the highest selectivity of ethylene was as high as 88.5%. After continuous reaction for 72 h, the activity decreased by 1.2% and the selectivity decreased by 1.0%.

[0057] Example 5

[0058] 1. Under the condition of 60 kHz ultrasonic wave, disperse metal phthalocyanine compounds (1 mg nickel phthalocyanine, 1 mg copper phthalocyanine) and 8 mg carbon nanotubes in 2 mg and 15 mg DMF (N, N-dimethylformamide) respectively. Subsequently, mix and stir the phthalocyanine compound solution and the carrier solution. Under the conditions of helium atmosphere, a vacuum degree of 500 Pa, a voltage between the electrodes of 1000 V, and a distance between the electrodes of 8 mm, treat the dried catalyst with plasma for 60 min. After the treatment is completed, filter the product and wash it 3 times with 17 mL DMF and ethanol (volume ratio 1:1), and then dry it in vacuum at 80 °C for 6 h. Pour the prepared catalyst and 15 μL of 5% nafion solution by mass fraction into 2 mL of n-propanol respectively, and perform ultrasonic treatment at 60 kHz for 1 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0059] 2. Cut the electrode material copper foam into 2 cm × 2 cm, and wash the copper foam with hydrochloric acid, ethanol and deionized water respectively to remove the impurities on the surface.

[0060] 3. Uniformly apply the solution obtained in step 1 to the electrode material obtained in step 2, and then irradiate the electrode material under an infrared lamp with a power of 180 W for 10 min to obtain the prepared supported nickel phthalocyanine and copper phthalocyanine electrodes.

[0061] Place the electrode obtained in step 3 at the cathode of an electrochemical fluid electrolytic cell (as Figure 4 shown), use the supported nickel phthalocyanine and copper phthalocyanine electrodes as the working electrode, select nickel foam as the anode, use 0.5 M NaOH solution as the electrolyte, control the electrocatalytic reaction temperature at 10 °C, control the cathode potential of the electrode at -0.6 V, and simultaneously introduce ethylene gas containing 2 vol% acetylene impurities into the working electrode, with an airspeed of 1000 h -1 . Under this condition, the highest conversion rate of acetylene is 98.1%, and at the same time, the highest selectivity of ethylene is as high as 96.4%. The activity of the continuous reaction decreases by 1.7% after 72 h, and the selectivity decreases by 1.8%.

[0062] Example 6

[0063] 1. Under the condition of 60 kHz ultrasonic wave, 3 mg of zinc phthalocyanine and 30 mg of graphdiyne are respectively dispersed in 3 mg and 30 mg of DMF (N, N-dimethylformamide). Subsequently, the phthalocyanine compound solution and the carrier solution are mixed and stirred. Under the conditions of argon atmosphere, a vacuum degree of 500 Pa, a voltage between the plates of 1000 V, and a distance between the plates of 8 mm, the dried catalyst is treated with plasma for 60 min. After the treatment is completed, the product is filtered and washed 3 times with 33 mL of DMF and ethanol (volume ratio 1:1), and then vacuum dried at 80 °C for 6 h. The prepared catalyst and 20 μL of 5% mass fraction nafion solution are respectively poured into 2 mL of ethanol, and ultrasonicated at 60 kHz for 1 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0064] 2. Cut the electrode material carbon paper into 1 cm × 1 cm, and wash the carbon paper with hydrochloric acid, ethanol and deionized water respectively to remove the surface impurities.

[0065] 3. Uniformly apply the solution obtained in step 1 to the electrode material obtained in step 2, and then place the electrode material under an infrared lamp with a power of 180 W for irradiation for 10 min to obtain the prepared supported zinc phthalocyanine electrode.

[0066] Place the electrode obtained in step 3 in an H-type electrolytic cell electrochemical device (as Figure 3 shown), use the supported zinc phthalocyanine electrode as the working electrode, select nickel foam as the anode, use 1 M NaOH solution as the electrolyte, control the electrocatalytic reaction temperature at 10 °C, control the cathode potential of the electrode at -0.6 V, and simultaneously introduce ethylene gas containing 5 vol% acetylene impurities into the working electrode, with an airspeed of 80000 h -1 . Under this condition, the highest conversion rate of acetylene is 91.1%, and at the same time, the highest selectivity of ethylene is as high as 91.2%. The activity of the continuous reaction for 72 h decreases by 4.2%, and the selectivity decreases by 3.2%.

[0067] Example 7

[0068] A method for the preparation and application of a metal phthalocyanine compound electrode for electrocatalytic acetylene hydrogenation reaction, comprising the following steps:

[0069] 1. Under the condition of 40 kHz ultrasonic wave, 2.5 mg of cobalt phthalocyanine and 10 mg of mesoporous carbon were respectively dispersed in 2.5 mg and 10 mg of DMF (N, N-dimethylformamide). Subsequently, the phthalocyanine compound solution and the carrier solution were mixed and stirred. Under the conditions of helium atmosphere, a vacuum degree of 100 Pa, a voltage between the electrodes of 1000 V, and a distance between the electrodes of 6 mm, the dried catalyst was treated with plasma for 60 min. After the treatment was completed, the product was filtered and washed 3 times with 12.5 mL of DMF and ethanol (volume ratio 1:1), and then vacuum dried at 80 °C for 6 h. The prepared catalyst and 12 μL of 5% nafion solution by mass were respectively poured into 3 mL of acetone and sonicated at 60 kHz for 1 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0070] 2. The electrode material carbon cloth was cut into 1.5×1.5 cm, and the carbon cloth was washed in hydrochloric acid, ethanol and deionized water respectively to remove the impurities on the surface.

[0071] 3. The solution obtained in step 1 was evenly coated on the electrode material obtained in step 2, and then the electrode material was irradiated under an infrared lamp with a power of 120 W for 27 min to obtain the prepared supported cobalt phthalocyanine electrode.

[0072] The electrode obtained in step 3 was placed at the cathode of an electrochemical fluid electrolytic cell. Using the supported cobalt phthalocyanine electrode as the working electrode, nickel foam was selected as the anode, and 1 M KOH solution was selected as the electrolyte. The temperature of the electrocatalytic reaction was controlled at 25 °C, the cathode potential of the electrode was controlled at -0.4 V, and at the same time, pure acetylene gas was fed to the working electrode with an airspeed of 3000 h -1 . Under this condition, the highest conversion rate of acetylene was 98.1%, and at the same time, the highest selectivity of ethylene was as high as 95.1%. After continuous reaction for 72 h, the activity decreased by 2.2% and the selectivity decreased by 1.2%.

[0073] During the electrocatalytic acetylene hydrogenation reaction, water molecules dissociated at the cathode to provide active hydrogen for in-situ hydrogenation of acetylene (C2H2 + 2H2O + 2e - →C2H4 + 2OH - ). Taking Example 1 as an example, no additional hydrogen gas was introduced as the reaction gas during the catalytic reaction process, so the reaction was not affected by the raw material gas ratio.

[0074] Comparative Example 1: Electro-catalytic acetylene hydrogenation and thermal-catalytic acetylene hydrogenation at the same temperature

[0075] A commercial palladium-based catalyst (5% palladium-carbon hydrogenation catalyst (Wokai) 25G, Sinopharm reagent, cas7440-05-3) was selected as the catalyst for the thermal-catalytic acetylene hydrogenation reaction: temperature 25 °C, acetylene airspeed 3000 h -1, carried out under the condition of n(C2H2):n(H2) = 1:1.1. The conversion rate of acetylene in thermal catalytic acetylene hydrogenation is 23%, and the selectivity is 15%.

[0076] Comparative Example 2: Electro-catalytic acetylene hydrogenation and thermal catalytic acetylene hydrogenation under the condition of an equal proportion of reaction gas

[0077] Select a commercial palladium-based catalyst (5% palladium-carbon hydrogenation catalyst (Wokai) 25G, Sinopharm reagent, cas7440-05-3) as the catalyst for thermal catalytic acetylene hydrogenation. The reaction conditions are: temperature 180 °C, the space velocity of acetylene is 3000 h -1 , carried out under the condition of n(C2H2):n(H2) = 1:1. The conversion rate of acetylene in thermal catalytic acetylene hydrogenation is 82.1%, and the selectivity is 57.1%.

[0078] Comparative Example 3: Example 1 and Comparative Example 3 are compared to illustrate the influence of plasma treatment on catalytic activity and stability.

[0079] I. Under the condition of 20 kHz ultrasound, 3 mg of copper phthalocyanine and 15 mg of mesoporous carbon are respectively dispersed in 3 mg and 15 mg of DMF (N,N-dimethylformamide). Subsequently, the phthalocyanine compound solution and the carrier solution are mixed and stirred. The processed product is filtered and washed 3 times with 18 mL of DMF and ethanol (volume ratio 1:1), and vacuum dried at 80 °C for 6 h. Take the prepared catalyst and 12 μL of 5% mass fraction nafion solution and pour them into 3 mL of acetone respectively, and ultrasonicate at 20 kHz for 1 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0080] II. Cut the electrode material carbon cloth into 1×1 cm, and wash the carbon cloth with hydrochloric acid, ethanol and deionized water respectively to remove the surface impurities.

[0081] III. Uniformly apply the slurry obtained in step I to the electrode material obtained in step II, and then irradiate the electrode material under an infrared lamp with a power of 100 W for 30 min to obtain the prepared supported copper phthalocyanine electrode.

[0082] Place the electrode obtained in step III at the cathode of an electrochemical fluid electrolytic cell (as Figure 4 shown), use the supported copper phthalocyanine electrode as the working electrode, select nickel foam as the anode, use 1 M KOH solution as the electrolyte, control the electrocatalytic reaction temperature at 25 °C, control the cathode potential of the electrode at -1.0 V, and simultaneously introduce ethylene gas containing 3 vol% acetylene impurities into the working electrode, with a space velocity of 3000 h -1 . Under this condition, the highest conversion rate of acetylene is 92.1%, and at the same time, the highest selectivity of ethylene is as high as 89.1%. The activity of the continuous reaction for 72 h decreases by 35.2%, and the selectivity decreases by 18.2%.

[0083] Comparative Example 4: The comparison between Example 1 and Comparative Example 4 shows that the addition of the carrier improves the stability and activity of the catalyst.

[0084] A method for preparing and applying a metal phthalocyanine compound electrode for electrocatalytic acetylene hydrogenation reaction, comprising the following steps:

[0085] I. Under the ultrasonic condition of 20 kHz, disperse 3 mg of copper phthalocyanine in 3 mg of DMF (N,N-dimethylformamide). Under the conditions of helium atmosphere, a vacuum degree of 100 Pa, a voltage between the electrodes of 1000 V, and a distance between the electrodes of 6 mm, treat the dried catalyst with plasma for 60 min. After the treatment is completed, filter the product and wash it 3 times with 18 mL of DMF and ethanol (volume ratio 1:1), and then vacuum dry it at 80 °C for 6 h. Pour the prepared catalyst and 12 μL of 5% mass fraction nafion solution into 3 mL of acetone respectively, and ultrasonically treat it at 20 kHz for 1 h to assist the solute to dissolve into the organic solvent to obtain a slurry.

[0086] II. Cut the electrode material carbon cloth into 1 cm × 1 cm, and wash the carbon cloth with hydrochloric acid, ethanol and deionized water respectively to remove the surface impurities.

[0087] III. Uniformly apply the solution obtained in step I to the electrode material obtained in step II, and then place the electrode material under an infrared lamp with a power of 100 W for irradiation for 30 min to obtain the prepared supported copper phthalocyanine electrode.

[0088] Place the electrode obtained in step III at the cathode of an electrochemical fluid electrolytic cell (as shown in Figure 4 ), use the supported copper phthalocyanine electrode as the working electrode, select nickel foam as the anode, use 1 M KOH solution as the electrolyte, control the electrocatalytic reaction temperature at 25 °C, control the cathode potential of the electrode at -1.0 V, and simultaneously introduce ethylene gas containing 3 vol% acetylene impurities into the working electrode, with an airspeed of 3000 h -1 . Under this condition, the highest conversion rate of acetylene is 95.1%, and at the same time, the highest selectivity of ethylene is as high as 93.1%. After continuous reaction for 72 h, the activity decreases by 22.2% and the selectivity decreases by 23.2%.

Claims

1. A preparation method of a supported metal phthalocyanine compound electrode for electrocatalytic selective hydrogenation of acetylene, characterized in that: The preparation method is carried out according to the following steps: Step 1: Under ultrasonic conditions, the metal phthalocyanine compound and the carrier are respectively dispersed in DMF. Subsequently, the metal phthalocyanine compound solution and the carrier solution are mixed and stirred, and treated with plasma. After the treatment is completed, filtration is carried out to obtain a solid product, which is then washed, dried. The prepared catalyst and a 5% mass fraction nafion solution are respectively poured into an organic solvent, and ultrasonic treatment is carried out to assist the solute to dissolve into the organic solvent to obtain a slurry; the carrier is mesoporous carbon, graphene or carbon nanotube; the mass ratio between the metal phthalocyanine compound and the carrier is (1 - 3 mg):(4 - 30 mg), and the mass volume ratio of the metal phthalocyanine compound to the 5% mass fraction nafion solution is (1 - 3 mg) / (5 - 20 μL); the metal phthalocyanine compound powder is selected from at least one of copper phthalocyanine, cobalt phthalocyanine, and nickel phthalocyanine; Step 2: The cut electrode material is washed with hydrochloric acid, ethanol and deionized water; Step 3: The slurry obtained in Step 1 is evenly coated on the electrode material obtained in Step 2, and irradiated with an infrared lamp until the solution is completely dried to obtain a supported metal phthalocyanine compound electrode.

2. The preparation method according to claim 1, characterized in that: The organic solvent described in Step 1 is selected from at least one of acetone, ethanol, isobutanol, ethylene glycol, n-propanol and isopropanol.

3. The preparation method according to claim 1, wherein: In Step 1, the mass volume ratio of the metal phthalocyanine compound to the organic solvent is (1 - 3 mg) / (1 - 3 mL).

4. The preparation method according to claim 1, characterized in that: In Step 1, the washing solution is a mixed solvent of DMF and ethanol, and the volume ratio of DMF to ethanol is 1:

1.

5. The preparation method according to claim 1, characterized in that: The plasma treatment conditions in Step 1 are: the vacuum degree is 50 - 1000 Pa, the plasma working gas is one or a mixture of argon, nitrogen, argon, hydrogen, etc., the voltage between the electrodes is 200 - 5000 V, the distance between the electrodes is 6 - 10 mm, and the plasma treatment time is 10 - 240 minutes.

6. The preparation method according to claim 1, characterized in that: In Step 2, the electrode material is carbonaceous, carbon cloth, copper foam or nickel foam.

7. The preparation method according to claim 1, characterized in that: In Step 3, the power of the infrared lamp is 100 - 200 W, and the irradiation time is 10 - 30 min.

8. A method for electrocatalytic selective hydrogenation of acetylene, characterized in that: The method includes: placing the supported metal phthalocyanine compound electrode prepared by the preparation method described in claim 1 at the cathode of an electrochemical device as a working electrode, setting the reaction temperature for the electrocatalytic selective hydrogenation of acetylene to be carried out at a temperature of -10 to 40 °C, and introducing a raw material gas containing acetylene with an hourly space velocity of 500 to 80,000 h -1 into the working electrode, and converting it into ethylene through the electrocatalytic selective hydrogenation reaction of acetylene.

9. The method according to claim 8, characterized in that: The acetylene-containing raw material gas is ethylene gas containing acetylene impurities with a volume fraction between 0.3% and 3%.

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