A method for preparing non-metal-doped carbon material for catalytic reduction of dilute nitric acid in water

Abstract

The invention discloses a method for preparing a non-metallic doped carbon material for catalytic reduction of dilute nitric acid in water, the preparation method being: adding a non-metallic reagent to a certain volume fraction of ethanol aqueous solution, continuously stirring under water bath conditions until uniform dispersion, and then adding a certain amount of powdered carbon material, stirring, aging, and drying, and then placing in a tubular furnace for calcination, while promoting the high temperature decomposition of the non-metallic reagent and the doping in the carbon material body. A sequencing batch gas-liquid contact reactor is used, and the reaction temperature is 60-80°C, the reaction pressure is 0.2-0.4MPa, the stirring rate is 300-600rpm, the methanol mass fraction in the liquid phase is 50%-80%, and the nitric acid mass fraction is 2%-10%. The NO-N2 mixed gas with a volume fraction of 20%-40% of NO is continuously passed into a reactor equipped with nitric acid and methanol reaction solution for a period of time, and compared with an undoped carbon catalyst, under the action of the prepared non-metallic doped carbon-based catalyst, the nitric acid conversion rate is further improved.

Description

Technical Field

[0001] The present invention relates to a method for preparing a non-metal-doped carbon material for catalytic reduction of dilute nitric acid in water. The catalyst can improve the conversion rate of dilute nitric acid in wastewater and is mainly used for the catalytic conversion of dilute nitric acid in wastewater generated during the regeneration process of alkyl nitrite in the coal-to-ethylene glycol industry. Background Art

[0002] Ethylene glycol is an important petrochemical product, mainly used in the production of polyester fiber, antifreeze and dynamic chemical products, and is mainly produced through petroleum routes and non-petroleum routes. In recent years, with the rapid development of my country's polyester industry, the demand for ethylene glycol has continued to increase. Since my country has an energy structure characterized by abundant coal, little gas and lack of oil, the development of coal-to-ethylene glycol technology provides a technical route for the production of ethylene glycol through non-petroleum routes, which can effectively alleviate the prominent contradiction between ethylene glycol supply and demand in my country. The coal-to-ethylene glycol process has become increasingly mature, and many sets of coal-to-ethylene glycol industrial plants have been built in China. The coal-to-ethylene glycol process mainly realizes the conversion of inorganic carbon to organic carbon and the recycling of resources through processes such as CO coupling esterification, hydrogenation reduction, distillation separation and oxidative esterification.

[0003] The oxidative esterification process is a key step in the coal-to-ethylene glycol process. Methyl nitrite is generated by the reaction between nitrogen oxides, oxygen and methanol. However, due to the complexity of the reaction process, in addition to generating methyl nitrite feed gas, a large amount of dilute nitric acid waste liquid is also generated, in which the mass fraction of dilute nitric acid is about 1% to 10%. The generation of dilute nitric acid will not only increase the replenishment cost of nitrogen oxides, but also cause corrosion of equipment. At present, the treatment method for dilute nitric acid wastewater is mainly to discharge it after alkali neutralization, but the direct discharge of nitrate wastewater generated by neutralization will cause eutrophication of water bodies. Therefore, it is of great significance to further convert the dilute nitric acid in the wastewater and realize the resource utilization of dilute nitric acid. The reduction conversion of dilute nitric acid can be achieved by causing an oxidation-reduction reaction between nitric oxide, methanol and nitric acid through a gas-liquid contact reactor such as a fixed bed or a reactor. However, the process conditions required to achieve a high conversion rate of dilute nitric acid without a catalyst are relatively harsh and consume a lot of energy.

[0004] Based on the above introduction, the present invention uses cheap and readily available carbon materials as the main body, and dopes non-metallic elements into the carbon material main body by combining liquid phase water bath treatment and high temperature calcination to prepare a non-metallic doped carbon catalyst. The catalyst has a high specific surface area and active sites, can effectively adsorb NO in the gas phase, improve the gas-liquid contact efficiency, and thus improve the conversion rate of dilute nitric acid. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a non-metal-doped carbon material for catalytic reduction of dilute nitric acid in water, using a cheap and easy-to-prepare carbon material as the main body, and using a water bath treatment and high-temperature calcination method to prepare a non-metal-doped carbon catalyst. When reacting in a gas-liquid contact reactor, the prepared non-metal-doped carbon catalyst can effectively improve the conversion rate of dilute nitric acid.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a non-metal-doped carbon material for catalytic reduction of dilute nitric acid in water, the preparation method comprising: adding a non-metal source reagent to an ethanol aqueous solution with a certain volume fraction, and continuously stirring in a water bath until the non-metal source reagent is completely dissolved or evenly dispersed, weighing a certain amount of powdered carbon material and adding it to the mixed solution, and continuing to stir and age for a certain period of time under the same conditions, placing the mixed solution in a blast drying oven to evaporate the solvent, and finally placing the dried carbon material in a nitrogen atmosphere tubular furnace for calcination, while promoting high-temperature decomposition of the non-metal source reagent and doping in the carbon material body. A sequencing batch gas-liquid contact reactor reaction device is used, and the reaction temperature is 60-80°C, the reaction pressure is 0.2-0.4MPa, the stirring rate is 300-600rpm, the methanol mass fraction in the liquid phase is 50%-80%, and the nitric acid mass fraction is 2-10%. A NO-N2 mixed gas with a NO volume fraction of 20-40% is continuously introduced into a reactor containing nitric acid and methanol reaction liquid. After a certain reaction time, compared with an undoped carbon catalyst, the nitric acid conversion rate is further improved under the action of the prepared non-metal doped carbon-based catalyst. According to the above scheme, the concentration of the ethanol aqueous solution is preferably 30%-70%.

[0008] According to the above scheme, the non-metal source reagent is preferably one of boron-containing reagents such as boric acid and sodium borohydride, or nitrogen-containing reagents such as dicyandiamide and melamine.

[0009] According to the above scheme, the water bath temperature is preferably 40-80°C, more preferably 40-60°C, and the aging time is preferably 1-6h.

[0010] According to the above scheme, the carbon-based material can be one of activated carbon, graphene, carbon nanotubes, carbon fiber, mesoporous carbon or graphite, and the particle size is preferably 60-100 meshes.

[0011] According to the above scheme, the calcination temperature is preferably 500-100°C, more preferably 600-800°C, and the heating rate is preferably 2°C / min-10°C / min.

[0012] According to the above scheme, the mass ratio of the carbon-based material to the doped non-metallic source reagent is controlled to be 2:1 to 10:1.

[0013] The reaction device adopted in the present invention is a sequencing batch gas-liquid contact reactor.

[0014] According to the above scheme, the temperature in the reactor is 60-80°C, the reaction pressure is 0.2-0.4 MPa, and the stirring rate is 300-600 rpm.

[0015] According to the above scheme, the volume fraction of NO in the gas phase is 20% to 40%, the ventilation time is preferably 60 to 180 minutes, and the total amount of NO introduced is 1 to 2 times the theoretical calculated value.

[0016] According to the above scheme, the mass fraction of methanol in the liquid phase is 50% to 80%, and the mass fraction of nitric acid is 2% to 10%.

[0017] According to the above scheme, the mass ratio of the reaction liquid added to the reactor to the catalyst is preferably 20:1 to 40:1.

[0018] According to the above scheme, compared with undoped carbon-based catalysts, non-metal-doped carbon-based catalysts can further enhance the adsorption and capture of NO gas in the gas phase, increase the gas-liquid contact efficiency, and thus further improve the conversion rate of dilute nitric acid in wastewater.

[0019] Compared with the prior art, the present invention has the following outstanding advantages and characteristics:

[0020] First, the catalyst preparation method described in the method is simple to operate and has mild conditions;

[0021] Second, the carbon-based main material and the doped non-metallic source reagent selected by the catalyst are abundant in production and low in cost;

[0022] Third, the catalyst can effectively reduce the process conditions of the nitric acid catalytic reduction reaction and improve the conversion rate of dilute nitric acid in the wastewater during the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Scanning electron microscope images of carbon catalysts doped with different non-metals; undoped AC (a); C2H4N4-AC-600-2: 1 (b); C2H4N4-AC-700-5: 1 (c); C2H4N4-AC-700-10: 1 (d); C2H4N4-AC-800-10: 1 (e); HBO3-AC-700-5: 1 (f); HBO3-AC-800-5: 1 (g); HBO3-AC-800-10: 1 (h); DETAILED DESCRIPTION

[0024] In order to deepen the understanding of the present invention, the present invention is further described in detail below in conjunction with specific implementation cases. The following embodiments are only used for illustration, but the content of the present invention is not limited thereto.

[0025] Comparative Example 1

[0026] Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%. After sealing, heat it to 60°C, then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after 90 minutes of reaction, and measure the nitric acid concentration in the remaining solution by titration after cooling to room temperature, and calculate the nitric acid conversion rate X HNO3 It is 33.43%.

[0027] Comparative Example 2

[0028] Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of undoped activated carbon catalyst, seal it and heat it to 60°C, then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after 90 minutes of reaction, and measure the nitric acid concentration in the remaining solution by titration after cooling to room temperature, and calculate the nitric acid conversion rate X HNO3 It is 52.32%.

[0029] Example 1

[0030] (1) Weigh 5 g of dicyandiamide reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0031] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 hours under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0032] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 600°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 h, and then cooled to room temperature. The material was taken out and placed in a desiccator for storage.

[0033] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce NO-N2 mixed gas with a NO volume fraction of 30% mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 minutes, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 57.72%.

[0034] Example 2

[0035] (1) Weigh 2 g of dicyandiamide reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0036] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 hours under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0037] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 700°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 h, and then cooled to room temperature. The material was taken out and placed in a desiccator for storage.

[0038] (4) Add 20 mL of the prepared nitric acid-methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of the boron-doped activated carbon prepared in step (3), seal it and heat it to 60° C., then introduce the NO-N2 mixed gas with a NO volume fraction of 30% mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 minutes, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 65.57%.

[0039] Example 3

[0040] (1) Weigh 1 g of dicyandiamide reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0041] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0042] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 600°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 h, and then cooled to room temperature. The material was taken out and placed in a desiccator for storage.

[0043] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce NO-N2 mixed gas with a NO volume fraction of 30% mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 minutes, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 59.95%.

[0044] Example 4

[0045] (1) Weigh 1 g of dicyandiamide reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0046] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0047] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 700°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 hours, and then cooled to room temperature. The material was removed and stored in a desiccator.

[0048] (4) Add 20 mL of the prepared nitric acid-methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of the boron-doped activated carbon prepared in step (3), seal it, and heat it to 60° C., then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 minutes, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 60.45%.

[0049] Example 5

[0050] (1) Weigh 1 g of dicyandiamide reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0051] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0052] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 800°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 hours, and then cooled to room temperature. The material was removed and stored in a desiccator.

[0053] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 min, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 58.48%.

[0054] Example 6

[0055] (1) Weigh 2 g of boric acid reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0056] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0057] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 600°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 hours, and then cooled to room temperature. The material was removed and stored in a desiccator.

[0058] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 min, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 57.44%.

[0059] Example 7

[0060] (1) Weigh 2 g of boric acid reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0061] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0062] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 700°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 hours, and then cooled to room temperature. The material was removed and stored in a desiccator.

[0063] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 min, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate XHNO3 It is 62.12%.

[0064] Example 8

[0065] (1) Weigh 2 g of boric acid reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0066] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0067] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 800°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 hours, and then cooled to room temperature. The material was removed and stored in a desiccator.

[0068] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 min, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 64.19%.

[0069] Example 9

[0070] (1) Weigh 1 g of boric acid reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0071] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0072] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 700°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 hours, and then cooled to room temperature. The material was removed and stored in a desiccator.

[0073] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 min, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 60.43%.

[0074] Example 10

[0075] (1) Weigh 1 g of boric acid reagent and dissolve it in 40 mL of 50% ethanol solution, and place it in a water bath at 40° C. until the boric acid particles are completely dissolved;

[0076] (2) slowly adding 100-mesh activated carbon powder to the mixed solution under the water bath condition, stirring and aging for 3 h under the water bath condition, and then placing the mixed solution in a forced air drying oven to evaporate the solvent;

[0077] (3) The dried material was placed in a nitrogen atmosphere tubular furnace, heated to 800°C at a rate of 10°C / min, maintained at this temperature for calcination for 2 hours, and then cooled to room temperature. The material was removed and stored in a desiccator.

[0078] (4) Add 20 mL of prepared nitric acid and methanol reaction solution into a 50 mL reactor, wherein the mass fraction of nitric acid is 5% and the mass fraction of methanol is 80%, then add 1 g of boron-doped activated carbon prepared in step (3), seal and heat to 60° C., then introduce 30% NO gas mixed in advance into the reactor below the liquid level at a rate of 34.6 mL / min, maintain the reactor pressure at 0.2 MPa, control the stirring rate at 500 rpm to ensure sufficient contact between gas and liquid, stop heating and ventilation after reacting for 90 min, and after cooling to room temperature, measure the nitric acid concentration in the remaining solution by titration, and calculate the nitric acid conversion rate X HNO3 It is 65.54%.

[0079] Table 1 shows the element mass distribution of non-metal-doped carbon catalyst materials with different proportions, and Table 2 shows the non-metal-doped carbon materials prepared in different embodiments and their nitric acid conversion rates

[0080] Table 1 shows the element mass distribution of non-metal-doped carbon catalyst materials prepared with different ratios

[0081]

[0082]

[0083] Table 2 shows the non-metal-doped carbon materials prepared in different embodiments and their nitric acid conversion rates

[0084] Specific implementation cases catalyst Ratio of non-metal source reagent to carbon material Calcination temperature (℃) Nitric acid conversion rate (%) Comparative Example 1 none / / 33.43 Comparative Example 2 AC / 600 52.32 Example 1 <![CDATA[C2H4N4-AC]]> 2：1 600 57.72 Example 2 <![CDATA[C2H4N4-AC]]> 5：1 700 65.57 Example 3 <![CDATA[C2H4N4-AC]]> 10：1 600 59.95 Example 4 <![CDATA[C2H4N4-AC]]> 10：1 700 60.45 Example 5 <![CDATA[C2H4N4-AC]]> 10：1 800 58.48 Example 6 <![CDATA[HBO3-AC]]> 5：1 600 57.44 Example 7 <![CDATA[HBO3-AC]]> 5：1 700 62.12 Example 8 <![CDATA[HBO3-AC]]> 5：1 800 64.19 Example 9 <![CDATA[HBO3-AC]]> 10：1 700 60.43 Example 10 <![CDATA[HBO3-AC]]> 10：1 800 65.54

[0085] From the analysis in Table 1, it can be seen that the elemental composition of the carbon materials doped with non-metallic reagents in different proportions has changed significantly, indicating that the non-metallic doped activated carbon catalyst has been successfully prepared; the experimental results in Table 2 show that activated carbon has a certain catalytic effect on the nitric acid reduction reaction, and compared with undoped activated carbon, the nitric acid conversion rate is further improved under the action of carbon materials prepared by calcination at different doping amounts and different temperatures.

Claims

1. A method for preparing a non-metal-doped carbon material for catalytic reduction of dilute nitric acid in water, characterized in that: A sequencing batch gas-liquid contact reactor is used as a reaction device; the preparation method of the non-metallic doped carbon material is as follows: a non-metallic source reagent is added to an ethanol aqueous solution with a certain volume fraction, and the non-metallic source reagent is continuously stirred under a water bath condition until the non-metallic source reagent is completely dissolved or evenly dispersed, a certain amount of powdered carbon material is weighed and added to the above mixed solution, and the mixture is continuously stirred and aged for a certain period of time under the same condition, and then placed in a blast drying oven to evaporate the solvent, and finally the dried carbon material is placed in a nitrogen atmosphere tubular furnace for calcination, while promoting the high-temperature decomposition of the non-metallic source reagent and the doping in the carbon material body; Wherein, the water bath temperature is 40-80°C, the aging time is 1-6h; the particle size of the carbon material is 60-200 mesh; The calcination temperature is 700-800°C, and the heating rate is 2°C / min-10°C / min; Control the reaction kettle reaction temperature to 60-80°C, the reaction pressure to 0.2-0.4MPa, and the stirring rate to 300-600rpm; The volume fraction of NO in the gas phase is 20% to 40%, and the ventilation time is 60 to 180 minutes; The mass fraction of methanol in the liquid phase is 50% to 80%, and the mass fraction of nitric acid is 2% to 10%; The mass ratio of the reaction liquid to the catalyst added to the reactor is 20:1 to 40:1; The mass ratio of the carbon material to the doped non-metallic source reagent is controlled to be 5:1 to 10:1; The total amount of NO introduced is 1 to 2 times the theoretical calculated value; the concentration of the ethanol aqueous solution is 30% to 70%; The non-metal source reagent is at least one of boric acid, sodium borohydride, or dicyandiamide and melamine containing nitrogen; The carbon material is one of activated carbon, graphene, carbon nanotubes, carbon fibers, mesoporous carbon or graphite carbon.

2. A method for preparing a non-metal-doped carbon material for catalytic reduction of dilute nitric acid in water as claimed in claim 1, characterized in that: Under the above conditions, compared with the undoped carbon catalyst, the non-metal-doped carbon catalyst can further enhance the adsorption and capture of NO gas in the gas phase, increase the gas-liquid contact efficiency, and thus further improve the conversion rate of dilute nitric acid in wastewater.

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