A conversion CH 4 and CO 2 Direct method for preparing acetic acid

Abstract

The present invention relates to a method for directly preparing acetic acid by converting CH4 and CO2. First, a macroporous alumina carrier is prepared, and then a macroporous alumina-loaded transition metal single-atom catalyst is prepared by an impregnation method, which is used for plasma activation of CH4 and CO2 to directly generate acetic acid. The method of the present invention realizes the conversion of CH4 and CO2 into high-value-added acetic acid under normal temperature and pressure conditions, avoiding the high temperature and high pressure required for the traditional CH4 and CO2 reaction, and the macroporous alumina-loaded transition metal single-atom catalyst in the present invention has good acetic acid selectivity and stability.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and relates to a method for directly preparing acetic acid by converting CH4 and CO2; in particular, it relates to a method for preparing a macroporous alumina-supported transition metal single-atom catalyst and its application. Background Art

[0002] The direct reaction of CH4 and CO2 to produce acetic acid is an atom-economic reaction that can not only produce valuable chemical products, but also has great significance for reducing the greenhouse effect. In industry, acetic acid is an important organic chemical raw material, widely used in synthetic fiber, medicine, pesticide and other processes, and is an important part of my country's real economy. The preparation methods of acetic acid include ethanol oxidation to acetic acid, methanol carbonylation, low-carbon alkane liquid phase oxidation, acetaldehyde oxidation and ethylene oxidation. However, these preparation processes usually require precious metals as catalysts, and the reaction is usually carried out in more than two steps, which undoubtedly increases the cost of the process.

[0003] Scientists at home and abroad have conducted some research on the topic of direct conversion of CH4 and CO2 to produce acetic acid. For example, Huang Wei and others from Taiyuan University of Technology used a two-step step conversion technology to achieve catalytic conversion of CH4 and CO2 to produce acetic acid, using Cu / Co bimetallic catalysts (Journal of Catalysis, 2001, 201, 100), Pd / C and Pt / Al2O3 catalysts (Catalysis Today, 2003, 88, 83), Pd / SiO2 and Rh / SiO2 catalysts (Fuel Processing Technology, 2007, 88, 319) to activate CH4 and CO2. However, because the two-step method is an intermittent operation, loading and unloading and separation are relatively complicated, resulting in low selectivity of acetic acid, and its preparation process often needs to be carried out at a temperature of 200 to 500°C, the catalyst is prone to carbon deposition and deactivation, and the generated acetic acid will also decompose at high temperatures. In view of the above problems, the use of plasma technology to catalyze CH4 and CO2 to produce acetic acid has significant advantages.

[0004] At present, there are public literature studies on the use of plasma to co-convert CH4 and CO2 into high-value chemical products. For example, Li et al. used Fe / SiO2 and Co / SiO2 as catalysts to catalyze CH4 and CO2 to produce liquid products through dielectric barrier discharge plasma, in which the selectivity of oxygen-containing compounds reached 40%, including acetic acid and alcohols. By comparing the selectivity of different products, it was found that Fe / SiO2 catalyst is conducive to the production of ethanol from CH4 and CO2, while Co / SiO2 is conducive to the production of acid products and long-chain alkanes. (Applied Catalysis B: Environmental, 2020, 261, 118228).

[0005] In the process of CH4 and CO2 conversion and utilization, most of the catalysts used are supported catalysts, and the various performance characteristics of supported catalysts often depend on the carrier; because the carrier determines the dispersion state of active metals in the catalyst, the acid properties of the catalyst, the mass transfer process within the catalyst particles, the strength of the catalyst, etc. A typical carrier, alumina, has been proven by a large number of experimental studies to effectively promote the dispersion of active metals. At the same time, because there are some hydroxyl groups and exposed aluminum atoms on the surface of alumina, it exhibits the characteristics of B acid and L acid. This surface acidity promotes the catalytic effect of alumina itself on the cracking of hydrocarbons and the generation of acid products. Different preparation methods can obtain alumina with different pore sizes. Among them, the catalyst prepared with macroporous alumina as the carrier can effectively reduce coking and avoid the decrease in activity or deactivation caused by the deposition of metal impurities, thereby extending the service life.

[0006] For supported metal catalysts, the efficiency of single-atom catalysis, in which each metal atom serves as an active site, will be greatly improved, while the metal utilization efficiency of traditional supported metal catalysts is far below the ideal level. Therefore, in order to maximize the catalytic efficiency of metals and reduce manufacturing costs, the preparation of single-atom metal catalysts has become the first choice for researchers. The superior catalytic performance of single-atom catalysts comes from the fact that when the particle dispersion reaches the single-atom size, many new properties are caused, such as sharply increased surface free energy, quantum size effect, unsaturated coordination environment and metal-support interaction. Summary of the invention

[0007] The purpose of the present invention is to improve the deficiencies of the prior art and provide a method for directly preparing acetic acid by converting CH4 and CO2. First, a macroporous alumina-supported transition metal single-atom catalyst is prepared and used to catalyze CH4 and CO2 to prepare acetic acid under plasma at normal temperature and pressure.

[0008] The technical solution of the present invention is: a method for directly preparing acetic acid by converting CH4 and CO2, and the specific steps are as follows:

[0009] A) Preparation of macroporous alumina-supported transition metal single atom catalysts;

[0010] (1) firstly uniformly mixing an alumina precursor and a pore-enlarging agent to obtain a mixture, then preparing a boric acid solution and adding it to the mixture for kneading and forming, and then drying and calcining to obtain a macroporous alumina carrier;

[0011] (2) dissolving the metal nitrate, then adding the macroporous alumina support obtained in step (1), and stirring at room temperature;

[0012] (3) The solution obtained in step (2) is filtered, washed, and dried, and then calcined under a protective atmosphere to obtain a macroporous alumina-supported transition metal single atom catalyst, which is denoted as SAs-M-Al2O3.

[0013] B) Preparation of acetic acid

[0014] The catalyst prepared in step A is loaded into the dielectric barrier discharge zone, and the discharge zone length and discharge gap size of the reactor are set; then CH4 and CO2 gases are introduced, and the power supply voltage and discharge frequency are adjusted to prepare acetic acid.

[0015] Preferably, the alumina precursor described in step A(1) is one of titanium-containing pseudo-boehmite, zirconium-containing pseudo-boehmite or phosphorus-containing pseudo-boehmite; the pore-enlarging agent is one of carbon black, cellulose and starch or a mixture of two of them; the boric acid solution is a boric acid aqueous solution or a boric acid-strong acid mixed aqueous solution, wherein the strong acid is one of nitric acid, phosphoric acid and hydrochloric acid; the mass ratio of boric acid, strong acid and deionized water in the boric acid solution is 1(0-1):(4-10).

[0016] Preferably, the mass of the pore expanding agent added in step A(1) is 3.0-10.0% of the mass of the alumina precursor; the mass of the boric acid solution added is 3.0-20.0% of the mass of the alumina precursor; the drying temperature is 90-150°C, and the drying time is 4-5h; the calcination temperature is 400-900°C, the heating rate is 2-8°C / min, and the calcination time is 2-4h.

[0017] Preferably, the metal nitrate described in step A(2) is one of iron nitrate, copper nitrate, nickel nitrate, cobalt nitrate, zinc nitrate or indium nitrate; the mass ratio of the metal nitrate to the macroporous alumina carrier is 1:(6-20); and the stirring time is 8-24h.

[0018] Preferably, the drying temperature in step A(3) is 80-150°C, and the drying time is 5-10 hours; the protective atmosphere is one of hydrogen, argon or helium, and the gas flow rate is 10-60 mL / min; the calcination reaction temperature is 200-900°C, the heating rate is 4-10°C / min, and the reaction time is 2-5 hours.

[0019] Preferably, the discharge zone length of the reactor in step B is 45-60 mm, and the discharge gap is 4-8 mm; at normal temperature and pressure, the molar ratio of CO2 and CH4 introduced is (0.2-2):1; the amount of catalyst used is the ratio of the mass of the catalyst to the volume of the discharge zone of 0.8-2 g / cm 3 ;The power supply voltage is 10~40V and the discharge frequency is 9~15kHz.

[0020] Beneficial effects:

[0021] The macroporous alumina-supported transition metal single-atom catalyst provided by the present invention can catalyze the direct conversion of CO2 and CH4 to prepare acetic acid at room temperature and pressure with plasma technology, and has good catalytic activity and acetic acid selectivity. DETAILED DESCRIPTION

[0022] The present invention is described in more detail below with examples. These examples are only descriptions of the best mode of implementation of the present invention and do not limit the protection scope of the present invention in any way.

[0023] Example 1

[0024] Step 1. Weigh 300g of titanium-containing pseudo-boehmite, 15g of carbon black and 10g of starch, and mix them evenly by grinding to obtain a mixture. Dissolve 2g of boric acid and 1g of phosphoric acid in 8mL of deionized water, add the above-mentioned boric acid-strong acid mixed aqueous solution to the mixture, knead it evenly into a plastic body, dry it at 110°C for 4h, and then heat the obtained solid to 800°C at a heating rate of 5°C / min, and keep it warm for 2h to obtain a macroporous alumina carrier.

[0025] Step 2. Weigh 1.0145g of ferric nitrate and 6.0870g of the alumina carrier obtained in step 1 to dissolve, stir at room temperature for 8h, then filter, wash, and dry in an oven at 80°C for 10h. After drying, the sample is reacted for 2h under hydrogen protection, with a hydrogen flow rate of 10mL / min, a reaction temperature of 540°C, and a heating rate of 5°C / min. A macroporous alumina-supported iron single-atom catalyst for the conversion of CO2 and CH4 to acetic acid under the normal temperature plasma is obtained, and the obtained catalyst is labeled as SAs-Fe-Al2O3.

[0026] Example 2

[0027] Step 1. Weigh 300g of zirconium-containing pseudo-boehmite, 18g of carbon black and 10g of starch, and grind them to mix them evenly to obtain a mixture. Dissolve 10g of boric acid in 50mL of deionized water, add the boric acid aqueous solution to the mixture, knead it evenly into a plastic body, dry it at 100°C for 5h, and then heat the obtained solid to 500°C at a heating rate of 3°C / min, and keep it warm for 3h to obtain a macroporous alumina carrier.

[0028] Step 2. Weigh 0.8941g of copper nitrate and 7.1528g of the alumina carrier prepared in step 1 to dissolve, stir at room temperature for 13h, then filter, wash, and dry in a 90°C oven for 7h. After drying, the sample is reacted for 3h under helium protection, with a helium flow rate of 15mL / min, a reaction temperature of 400°C, and a heating rate of 6°C / min. A macroporous alumina-supported copper single-atom catalyst for the conversion of CO2 and CH4 to acetic acid under the normal temperature plasma is obtained, and the obtained catalyst is labeled as SAs-Cu-Al2O3.

[0029] Example 3

[0030] Step 1. Weigh 350g of phosphorus-containing pseudo-boehmite and 13g of carbon black, and mix them evenly by grinding to obtain a mixture. Dissolve 6g of boric acid and 2g of nitric acid in 60mL of deionized water, add the above-mentioned boric acid-strong acid mixed aqueous solution to the mixture, knead it evenly into a plastic body, dry it at 120°C for 4h, and then heat the obtained solid to 450°C at a heating rate of 2°C / min, and keep it warm for 4h to obtain a macroporous alumina carrier.

[0031] Step 2. Weigh 1.4670g of nickel nitrate and 20.5380g of the alumina carrier prepared in step 1 to dissolve, stir at room temperature for 17h, then filter, wash, and dry in an oven at 110°C for 10h. The sample after drying is reacted for 5h under argon protection, with an argon flow rate of 20mL / min, a reaction temperature of 450°C, and a heating rate of 4°C / min. A macroporous alumina-supported nickel single-atom catalyst for the conversion of CO2 and CH4 to acetic acid under the normal temperature plasma is obtained, and the obtained catalyst is labeled as SAs-Ni-Al2O3.

[0032] Example 4

[0033] Step 1. Weigh 400g of titanium-containing pseudo-boehmite, and then weigh 26g of carbon black and 14g of cellulose, and mix them evenly by grinding to obtain a mixture. Dissolve 10g of boric acid and 5g of nitric acid in 60mL of deionized water, add the above-mentioned boric acid-strong acid mixed aqueous solution to the mixture, knead it evenly into a plastic body, dry it at 120°C for 4h, and then heat the obtained solid to 700°C at a heating rate of 8°C / min, and keep it warm for 2h to obtain a macroporous alumina carrier.

[0034] Step 2. Weigh 0.9771g of cobalt nitrate and 17.1450g of the alumina carrier prepared in step 1 to dissolve, stir at room temperature for 24h, then filter, wash, and dry in an oven at 120°C for 5h. After drying, the sample is reacted under hydrogen protection for 2h, the hydrogen flow rate is 40mL / min, the reaction temperature is 250°C, and the heating rate is 10°C / min. A macroporous alumina-supported cobalt single-atom catalyst for the conversion of CO2 and CH4 to acetic acid under the normal temperature plasma is obtained, and the obtained catalyst is labeled as SAs-Co-Al2O3.

[0035] Example 5

[0036] Step 1. Weigh 340g of zirconium-containing pseudo-boehmite, and then weigh 18g of starch and 10g of cellulose, and mix them evenly by grinding to obtain a mixture. Dissolve 10g of boric acid and 4g of phosphoric acid in 40mL of deionized water, add the above-mentioned boric acid-strong acid mixed aqueous solution to the mixture, knead it evenly into a plastic body, dry it at 140°C for 4h, and then heat the obtained solid to 600°C at a heating rate of 8°C / min, and keep it warm for 3h to obtain a macroporous alumina carrier.

[0037] Step 2. Weigh 1.7365g of zinc nitrate and 22.5745g of the alumina carrier prepared in step 1 to dissolve, stir at room temperature for 12h, then filter, wash, and dry in a 150°C oven for 6h. After drying, the sample is reacted for 2h under helium protection, with a helium flow rate of 50mL / min, a reaction temperature of 900°C, and a heating rate of 6°C / min. A macroporous alumina-supported zinc single-atom catalyst for the conversion of CO2 and CH4 to acetic acid under the normal temperature plasma is obtained, and the obtained catalyst is labeled as SAs-Zn-Al2O3.

[0038] Example 6

[0039] Step 1. Weigh 360g of titanium-containing pseudo-boehmite and 25g of starch, grind and mix them evenly to obtain a mixture. Dissolve 4g of boric acid and 1g of hydrochloric acid in 40mL of deionized water, add the above-mentioned boric acid-strong acid mixed aqueous solution to the mixture, knead and knead evenly into a plastic body, dry at 150°C for 5h, and then heat the obtained solid to 720°C at a heating rate of 7°C / min, and keep it warm for 2h to obtain a macroporous alumina carrier.

[0040] Step 2. Weigh 1.3108g of zinc nitrate and 25.5606g of the alumina carrier prepared in step 1 and dissolve them, stir at room temperature for 18h, then filter, wash, and dry in an oven at 110°C for 5h. After drying, the product was reacted under argon protection for 4h, the argon flow rate was 15mL / min, the reaction temperature was 550°C, and the heating rate was 8°C / min. A macroporous alumina-supported indium single-atom catalyst for the conversion of CO2 and CH4 to acetic acid under the normal temperature plasma was obtained, and the obtained catalyst was labeled SAs-In-Al2O3.

[0041] Application Example 1

[0042] The present invention prepares a macroporous alumina-loaded transition metal single-atom catalyst and uses plasma to catalyze CH4 and CO2 to directly produce acetic acid. The plasma reactor consists of two coaxial cylindrical glass tubes, with water circulating between the outer side of the inner glass tube and the inner side of the outer glass tube, serving as a grounding electrode; the high-voltage electrode of the reactor is placed on the axis of the coaxial glass tube. The discharge zone length of the reactor is 45 mm, and the discharge gap is 5 mm; 1.7 g of SAs-Fe-Al2O3 catalyst (prepared in Example 1) is filled into the dielectric barrier discharge zone, and at room temperature and pressure, the molar ratio of CO2 and CH4 introduced is 0.2:1, the power input voltage is 15 V, and the discharge frequency is 10.0 kHz. Under the above conditions, the acetic acid selectivity is 78.16%, and the space-time yield of acetic acid is 184 mmol kg cat -1 ·h -1 .

[0043] Application Example 2

[0044] The present invention prepares a macroporous alumina-loaded transition metal single-atom catalyst and uses plasma to catalyze CH4 and CO2 to directly produce acetic acid. The plasma reactor consists of two coaxial cylindrical glass tubes, with water circulating between the outer side of the inner glass tube and the inner side of the outer glass tube, serving as a grounding electrode; the high-voltage electrode of the reactor is placed on the axis of the coaxial glass tube. The discharge zone length of the reactor is 58 mm, and the discharge gap is 6 mm; 2.1 g of SAs-Cu-Al2O3 catalyst (prepared in Example 2) is filled into the dielectric barrier discharge zone, and at room temperature and pressure, the molar ratio of CO2 and CH4 introduced is 1:1, the power input voltage is 17 V, and the discharge frequency is 10.0 kHz. Under the above conditions, the acetic acid selectivity is 96.45%, and the space-time yield of acetic acid is 421 mmol kg cat -1 ·h -1 .

[0045] Application Example 3

[0046] The present invention prepares a macroporous alumina-loaded transition metal single-atom catalyst and uses plasma to catalyze CH4 and CO2 to directly produce acetic acid. The plasma reactor consists of two coaxial cylindrical glass tubes, and water circulates between the outer side of the inner glass tube and the inner side of the outer glass tube, which serves as a grounding electrode; the high-voltage electrode of the reactor is placed on the axis of the coaxial glass tube. The discharge zone length of the reactor is 60 mm, and the discharge gap is 6 mm; 2 g of SAs-Ni-Al2O3 catalyst (prepared in Example 3) is filled into the dielectric barrier discharge zone, and at room temperature and pressure, the molar ratio of CO2 and CH4 introduced is 0.8:1, the power input voltage is 20 V, and the discharge frequency is 12.0 kHz. Under the above conditions, the acetic acid selectivity is 88.73%, and the space-time yield of acetic acid is 374 mmol kg cat -1 ·h -1 .

[0047] Application Example 4

[0048] The present invention prepares a macroporous alumina-loaded transition metal single-atom catalyst and uses plasma to catalyze CH4 and CO2 to directly produce acetic acid. The plasma reactor consists of two coaxial cylindrical glass tubes, with water circulating between the outer side of the inner glass tube and the inner side of the outer glass tube, serving as a grounding electrode; the high-voltage electrode of the reactor is placed on the axis of the coaxial glass tube. The discharge zone length of the reactor is 60 mm, and the discharge gap is 8 mm; 3.8 g of SAs-Co-Al2O3 catalyst (prepared in Example 4) is filled into the dielectric barrier discharge zone, and at room temperature and pressure, the molar ratio of CO2 and CH4 introduced is 1.1:1, the power input voltage is 25 V, and the discharge frequency is 14.0 kHz. Under the above conditions, the acetic acid selectivity is 82.99%, and the space-time yield of acetic acid is 202 mmol kg cat -1 ·h -1 .

[0049] Application Example 5

[0050] The present invention prepares a macroporous alumina-loaded transition metal single-atom catalyst and uses plasma to catalyze CH4 and CO2 to directly produce acetic acid. The plasma reactor consists of two coaxial cylindrical glass tubes, with water circulating between the outer side of the inner glass tube and the inner side of the outer glass tube, serving as a grounding electrode; the high-voltage electrode of the reactor is placed on the axis of the coaxial glass tube. The discharge zone length of the reactor is 48 mm, and the discharge gap is 8 mm; 2.1 g of SAs-Zn-Al2O3 catalyst (prepared in Example 5) is filled into the dielectric barrier discharge zone, and at room temperature and pressure, the molar ratio of CO2 and CH4 introduced is 1.4:1, the power input voltage is 30 V, and the discharge frequency is 14.0 kHz. Under the above conditions, the acetic acid selectivity is 90.40%, and the space-time yield of acetic acid is 386 mmol kgcat -1 ·h -1 .

[0051] Application Example 6

[0052] The present invention prepares a macroporous alumina-loaded transition metal single-atom catalyst and uses plasma to catalyze CH4 and CO2 to directly produce acetic acid. The plasma reactor consists of two coaxial cylindrical glass tubes, with water circulating between the outer side of the inner glass tube and the inner side of the outer glass tube, serving as a grounding electrode; the high-voltage electrode of the reactor is placed on the axis of the coaxial glass tube. The discharge zone length of the reactor is 48 mm, and the discharge gap is 5 mm; 2.6 g of SAs-In-Al2O3 catalyst (prepared in Example 6) is filled into the dielectric barrier discharge zone, and at room temperature and pressure, the molar ratio of CO2 and CH4 introduced is 2:1, the power input voltage is 40 V, and the discharge frequency is 15.0 kHz. Under the above conditions, the acetic acid selectivity is 84.67%, and the space-time yield of acetic acid is 268 mmol kg cat -1 ·h -1 .

[0053] Comparative Example 1

[0054] Wang et al. used Cu / HZSM-5 as a catalyst and applied dielectric barrier discharge to convert CO2 and CH4 into chemical products with a selectivity of 17.65% for acetic acid. (Applied Catalysis B:Environmental 315(2022)121583)

[0055] Comparative Example 2

[0056] Li et al. used nickel foam as a carrier to prepare a series of nickel-based catalysts, using plasma technology to catalyze the conversion of CO2 and CH4 into oxygen-containing compounds, among which the highest selectivity of acetic acid was 18.08%. (Journal of CO2 Utilization52(2021)101675)

[0057] The performance test results of each SAs-M-Al2O3 catalyst are shown in Table 1. It can be seen from the comparative examples that, when using the catalyst and plasma technology to catalyze the conversion of CH4 and CO2 to prepare acetic acid, the macroporous alumina-supported transition metal single-atom catalyst prepared by the present invention has a higher selectivity for acetic acid, indicating that the single-atom catalyst prepared by this patent has a good effect on the reaction.

[0058] Table 1 SAs-M-Al2O3 catalyst performance test results

[0059]

Claims

1. A method for directly preparing acetic acid by converting CH4 and CO2, the specific steps of which are as follows: A) Preparation of macroporous alumina-supported transition metal single atom catalysts; (1) firstly uniformly mixing an alumina precursor and a pore-enlarging agent to obtain a mixture, then preparing a boric acid solution and adding it to the mixture for kneading and forming, and then drying and calcining to obtain a macroporous alumina carrier; wherein the mass of the pore-enlarging agent added is 3.0-10.0% of the mass of the alumina precursor; (2) dissolving the metal nitrate, then adding the macroporous alumina carrier obtained in step (1), and stirring; wherein the metal nitrate is one of iron nitrate, copper nitrate, nickel nitrate, cobalt nitrate, zinc nitrate or indium nitrate; the mass ratio of the metal nitrate to the macroporous alumina carrier is 1:(6-20); and the stirring time is 8-24 hours; (3) filtering, washing, and drying the solution obtained in step (2), and then calcining the solution under a protective atmosphere to obtain a macroporous alumina-supported transition metal single atom catalyst; B) Preparation of acetic acid The macroporous alumina-loaded transition metal single-atom catalyst prepared in step A is loaded into the dielectric barrier discharge zone, and the discharge zone length and discharge gap size of the reactor are set; CH4 and CO2 gases, power supply voltage and discharge frequency are adjusted to obtain acetic acid.

2. The method according to claim 1, characterized in that The alumina precursor described in step A (1) is one of titanium-containing pseudo-boehmite, zirconium-containing pseudo-boehmite or phosphorus-containing pseudo-boehmite; the pore-enlarging agent is one of carbon black, cellulose and starch or a mixture of two of them; the boric acid solution is an aqueous solution of boric acid or a mixed aqueous solution of boric acid and a strong acid, wherein the strong acid is one of nitric acid, phosphoric acid or hydrochloric acid; the mass ratio of boric acid, strong acid and deionized water in the boric acid solution is 1: (0~1): (4~10).

3. The method according to claim 1, characterized in that In step A (1), the mass of boric acid solution added is 3.0-20.0% of the mass of the alumina precursor; the drying temperature is 90-150°C, and the drying time is 4-5h; the calcination temperature is 400-900°C, the heating rate is 2-8°C / min, and the calcination time is 2-4h.

4. The method according to claim 1, characterized in that: The drying temperature in step A (3) is 80-150° C., and the drying time is 5-10 h. The protective atmosphere is one of hydrogen, argon or helium, and the gas flow rate is 10-60 mL / min. The calcination reaction temperature is 200-900° C., the heating rate is 4-10° C. / min, and the reaction time is 2-5 h.

5. The method according to claim 1, characterized in that: In step B, the discharge zone length of the reactor is 45-60 mm, the discharge gap is 4-8 mm; the molar ratio of CO2 and CH4 is (0.2-2): 1; the catalyst dosage is the ratio of the catalyst loading mass to the discharge zone volume of 0.8-2 g / cm 3 ; The power supply voltage is 10~40 V and the discharge frequency is 9~15kHz.

Images