Method for preparing nitrogen-doped biochar from yellow wine vinasse and application of nitrogen-doped biochar

Abstract

The method comprises the following steps: drying and crushing the yellow wine vinasse, adding the obtained vinasse powder and an activating agent into water, dipping, drying, and calcining for 1-3 hours at 400-800 DEG C in a nitrogen atmosphere; and washing the carbonized vinasse with diluted hydrochloric acid to prepare the nitrogen-doped biochar. The obtained nitrogen-doped biochar can be used for preparing a nitrogen-doped biochar supported noble metal catalyst, and is used for catalyzing the selective hydrogenation reaction of a nitro aromatic compound. According to the present invention, the yellow wine vinasse with the low production value is subjected to resource utilization, such that the economic value of the product is improved, the carrier cost is reduced, the selectivity of the obtained noble metal catalyst on o-chloroaniline and DND is more than 98%, the catalyst has characteristics of long cycle life and sulfide poisoning resistance, and the catalyst replacement cost due to catalyst deactivation is reduced; and the method has great industrial production value.

Description

Technical Field

[0001] The present invention relates to the field of resource utilization of yellow rice wine lees, and particularly to a method for preparing nitrogen-doped biochar from yellow rice wine lees and the application of the nitrogen-doped material in the selective hydrogenation of aromatic compounds. Background Art

[0002] The reaction of reducing nitroaromatic compounds to prepare aniline compounds has extensive applications in the field of organic synthesis. However, for nitroaromatic compounds with multiple reducible groups, the selective hydrogenation reduction reaction is a technical difficulty.

[0003] For example, 4,4'-diaminostilbene-2,2'-disulfonic acid (DSD acid) is a common chemical intermediate used in the production of fine chemical products such as fluorescent brighteners, dyes, and plasticizers. DSD acid is synthesized from p-nitrotoluene through sulfonation reaction, oxidation condensation reaction, and nitro reduction reaction. In the whole synthesis process, the last step of reducing 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS) to DSD acid is the most important one. Since both the two nitro groups and the carbon-carbon double bond in the DNS acid molecular formula are easily reducible groups, the activity of the catalyst is crucial for the reduction process. Too high activity will cause the carbon-carbon double bond to be reduced to form benzyl compounds, and too low activity will result in incomplete reduction of the nitro group, affecting the product quality. At present, the methods for preparing DSD acid by reducing DNS acid mainly include iron powder reduction and catalytic hydrogenation reduction. The iron powder reduction method produces a large amount of industrial wastewater during the production process, has a high solid waste discharge, a high iron content in the product, and serious environmental pollution, so the large-scale production of DSD acid is restricted. In recent years, catalytic hydrogenation technology has been widely concerned due to its environmental friendliness, less three wastes, and high product quality, and has good industrial application prospects. Shi Tianbing proposed using Pd / C as a catalyst, and for the first time, the content of DSD acid obtained by catalytic hydrogenation could reach 95.77%, and the content of by-products (benzyl compounds) was only 0.31%. Zhang Junhua et al. used a self-made Pt / C catalyst and obtained a mass fraction of DSD acid > 97.5% and a yield > 98.5%. These noble metal catalysts all use activated carbon as a carrier, and the price of porous activated carbon is relatively expensive, resulting in a high cost.

[0004] In addition, chloroaniline solution is an important class of organic synthesis intermediates, which are widely used in the synthesis of organic fine chemicals such as pharmaceuticals, plasticizers, and printing and dyeing auxiliaries. The main synthesis methods include iron powder reduction method, sodium sulfide reduction method, electrolytic reduction method, and catalytic hydrogenation reduction method. Currently, the industrial process for preparing chloroaniline mainly involves catalytic hydrogenation of the corresponding chloronitrobenzene. However, the catalytic hydrogenation of chloronitrobenzene to prepare chloroaniline is a relatively complex reaction, and a large number of side reactions occur during the catalytic hydrogenation process. Among them, hydrodechlorination is the most serious side reaction. Currently, there are two methods to prevent hydrodechlorination: one is to adjust the interaction between the metal and the support; the other is to prepare bimetallic or polymetallic catalysts. Bimetallic or polymetallic catalysts are generally supported on activated carbon, and the cost of activated carbon is also relatively high.

[0005] As one of the three major brewing wines in China, the output of yellow rice wine lees can reach about 500,000 tons. Yellow rice wine lees contain rich substances such as proteins, peptides, amino acids, starches, sugars, and cellulose, and are widely sourced and inexpensive, making them an ideal raw material for the preparation of biomass carbon that can be developed and utilized. CN105819443B discloses a method for preparing activated carbon from waste plant-based biomass, CN109928391A discloses a modified yellow rice wine lees-based activated carbon and its preparation method, CN110980731A discloses a method for preparing a high specific surface area yellow rice wine lees-based activated carbon material from waste lees, CN202110392011 discloses a yellow rice wine lees-based biochar for adsorbing multi-component organic pollutants and its preparation method, and so on. However, the lees raw materials used in the existing technologies are all white wine lees or by-product lees after biomass is used to produce ethanol; the utilization methods of the activated carbon prepared from lees are generally limited to the performance of adsorbing and catalytically oxidizing organic pollutants, and no further extended applications are discussed. Summary of the Invention

[0006] The object of the present invention is to overcome the defects in the above-mentioned existing technologies, and provide a nitrogen-doped biochar prepared from yellow rice wine lees, and use this nitrogen-doped biochar as a support to prepare a supported metal catalyst for the selective hydrogenation reaction of aromatic compounds.

[0007] The technical solution adopted by the present invention is:

[0008] A method for preparing nitrogen-doped biochar from yellow rice wine lees, the method being:

[0009] Dry and crush the yellow rice wine lees, add the obtained lees powder and an activator to water, impregnate and then dry, and calcine at a temperature of 400-800°C for 1-3 h under a nitrogen atmosphere; wash the obtained carbonized lees with dilute hydrochloric acid to obtain nitrogen-doped biochar;

[0010] The yellow rice wine lees are dried and crushed, generally crushed to 100-200 mesh to obtain lees powder.

[0011] The activator is one or more of ZnCl2, H3PO4, FeCl3, MnCl2, and H2SO4, preferably ZnCl2.

[0012] The mass ratio of the activator to the distillers grains powder is 0.5 - 4:1, preferably 2 - 3:1.

[0013] The mass ratio of the distillers grains powder to water is generally 1:7 - 10.

[0014] The impregnation time is generally 15 - 30 h, preferably 24 h.

[0015] The drying is generally carried out at a temperature of 100 - 120 °C for 15 - 30 h.

[0016] The calcination temperature is preferably 600 - 700 °C.

[0017] The heating rate during calcination is preferably 10 - 30 °C / min.

[0018] The concentration of the dilute hydrochloric acid is generally 1 - 3 mol / L, preferably 2 mol / L.

[0019] The volume dosage of the dilute hydrochloric acid is generally 50 - 160 mL / g based on the mass of the carbonized distillers grains.

[0020] The carbonized distillers grains are washed with dilute hydrochloric acid. Generally, the carbonized distillers grains are ground and then added to the dilute hydrochloric acid solution, heated and stirred, filtered, washed with water, and dried to obtain nitrogen-doped biochar.

[0021] The heating and stirring are generally carried out at a temperature of 70 - 80 °C for 4 - 8 h.

[0022] The filter cake obtained after filtration is washed with water until neutral, and then dried at 60 - 70 °C to obtain nitrogen-doped biochar.

[0023] The present invention also provides the nitrogen-doped biochar prepared by the above method.

[0024] The surface of the nitrogen-doped biochar prepared by the present invention contains functional groups such as pyrrole, pyridine, or amino compounds, or has a graphitized nitrogen structure.

[0025] In the nitrogen-doped biochar, the nitrogen content is 6.0 - 10.0%. The existence forms of nitrogen elements are generally pyrrole nitrogen, pyridine nitrogen, and graphitic nitrogen.

[0026] The specific surface area of the nitrogen-doped biochar is 800 - 1200 m 2 / g.

[0027] The present invention also provides the application of the nitrogen-doped biochar in the preparation of a nitrogen-doped biochar-supported noble metal catalyst.

[0028] Furthermore, the method for the application is as follows: the equal volume impregnation method is adopted, with nitrogen-doped biochar as the carrier, and the active component noble metal Pd or Pt is loaded to prepare a nitrogen-doped biochar supported noble metal catalyst.

[0029] The present invention also provides a nitrogen-doped biochar supported noble metal catalyst, which uses nitrogen-doped biochar as the carrier and is loaded with the active component Pd or Pt.

[0030] The loading amount of the active component is 0.5 - 3.0%.

[0031] The nitrogen-doped biochar supported noble metal catalyst is generally prepared by the following method: the equal volume impregnation method is adopted, with nitrogen-doped biochar as the carrier, immersed in the impregnation solution, and impregnated for 24 - 48 h. The impregnation solution is H2PtCl6 or H2PdCl6 solution. After impregnation, it is vacuum dried, then heated to 280 - 300 °C, and hydrogen is introduced for reduction to prepare a nitrogen-doped biochar supported noble metal catalyst.

[0032] Generally, the volume of the impregnation solution is equal to the bulk volume of the carrier.

[0033] The mass ratio of Pt or Pd element in the impregnation solution to the mass of the carrier is 0.5 - 3.0%.

[0034] Preferably, the vacuum drying is carried out at 100 - 110 °C for 8 - 10 h.

[0035] The heating rate is preferably 3 - 10 °C / min.

[0036] The reduction time is preferably 2 - 3 h.

[0037] The present invention also provides the application of the nitrogen-doped biochar supported noble metal catalyst in the selective hydrogenation reaction of nitroaromatic compounds.

[0038] Furthermore, the nitroaromatic compound is an aromatic compound containing two reduction groups at the same time, such as 4,4`-dinitrostilbene-2,2`-disulfonic acid (DNS acid) and o-chloronitrobenzene, and 4,4'-diaminostilbene-2,2'-disulfonic acid or o-chloroaniline is prepared through the selective hydrogenation reaction.

[0039] Furthermore, the preferred method for the application is as follows: 4,4`-dinitrostilbene-2,2`-disulfonic acid or o-chloronitrobenzene is dissolved in a solvent, the nitrogen-doped biochar supported noble metal catalyst is added, and under a hydrogen pressure of 1 - 2 MPa, it is heated to 40 - 90 °C (preferably 60 - 70 °C) for the selective hydrogenation reduction reaction. After the post-treatment of the reaction solution, 4,4'-diaminostilbene-2,2'-disulfonic acid or o-chloroaniline is respectively prepared, and the nitrogen-doped biochar supported noble metal catalyst is recovered for recycling use.

[0040] The solvent is water, anhydrous ethanol or a mixture of the two.

[0041] Furthermore, the reaction raw material is 4,4'-dinitrostilbene-2,2'-disulfonic acid, and acid is added before the reaction to adjust the pH value of the reaction solution to 6-7, and then the hydrogenation reaction is carried out.

[0042] The reaction time of the selective hydrogenation reduction reaction is preferably 30 to 90 minutes.

[0043] The amount of the nitrogen-doped biochar loaded with precious metal catalyst is 0.5% to 5.0% of the mass of the reaction raw material 4,4'-dinitrostilbene-2,2'-disulfonic acid or o-chloronitrobenzene, preferably 1% to 2%.

[0044] The post-treatment of the reaction solution is generally to filter the reaction solution, evaporate the filtrate to remove the solvent to obtain 4,4'-diaminostilbene-2,2'-disulfonic acid or o-chloroaniline, and the filter cake is the recovered nitrogen-doped biochar-loaded precious metal catalyst, which is directly recycled.

[0045] The volume usage of the solvent is generally 8 to 10 mL / g based on the mass of 4,4'-dinitrostilbene-2,2'-disulfonic acid or o-chloronitrobenzene.

[0046] The present invention uses rice wine lees as a carbon source and a nitrogen source, and prepares nitrogen-doped biochar through the steps of pretreatment, activation, carbonization, etc., and then uses the nitrogen-doped biochar as a carrier to prepare a catalyst suitable for the selective hydrogenation of aromatic compounds by adopting an equal volume impregnation method, which can not only improve the catalytic activity and selectivity of the series of reactions, but also realize the resource utilization of rice wine lees.

[0047] The beneficial effects of the present invention are:

[0048] 1. Using rice wine lees as raw material, nitrogen-doped biochar was produced in one step without adding exogenous nitrogen, which not only realized the resource utilization of rice wine lees, but also opened up new raw materials for the preparation of nitrogen-doped biochar.

[0049] 2. The nitrogen-doped biochar prepared from rice wine lees is used as a carrier to prepare the precious metal catalyst, which reduces the production cost of using ordinary activated carbon carriers. The price of rice wine lees is generally 500-600 yuan / ton, and the price of activated carbon is generally 8000-10000 yuan / ton. The present invention makes resource utilization of low-output rice wine lees, improves the economic value of the product, and reduces the carrier cost.

[0050] 3. The noble metal catalyst is used in the hydrogenation reaction of o-chloronitrobenzene. The conversion rate of o-chloronitrobenzene reaches 100%, the selectivity of o-chloroaniline is 99.31%, and the selectivity of aniline is 0. Compared with other activated carbon materials, the present invention can, to a certain extent, inhibit the dechlorination phenomenon in the hydrogenation reaction.

[0051] 4. The noble metal catalyst is used in the hydrogenation reaction of DNS acid. The conversion rate of DNS acid reaches 100%, and the selectivity of DND reaches 98.15%. Moreover, the catalyst of the present invention has a long cycle life. After 20 cycles of hydrogenation reaction, the catalytic activity and the selectivity of DSD acid of the catalyst remain about 95%. The activity and stability of the catalyst do not show obvious attenuation. However, for the noble metal catalyst supported on conventional activated carbon, with the increase of the cycle number, the catalytic activity decreases significantly. Experiments show that after 8 cycles of the catalyst, the selectivity drops below 40%. The noble metal catalyst provided by the present invention can resist sulfide poisoning, improve the service life of the catalyst, reduce the cost of catalyst deactivation and replacement, and has great industrial production value. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is the XPS analysis spectrum of the nitrogen-doped biochar prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0053] The following specific examples are used to further illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto.

[0054] Example 1

[0055] The yellow rice wine distillers' grains are dried, crushed, and sieved to 100 - 200 meshes to obtain yellow rice wine distillers' grains powder.

[0056] ZnCl2 and 2 g of yellow rice wine distillers' grains powder are put into a beaker according to a mass ratio of 2:1, 15 mL of deionized water is added and stirred for 24 h, and the beaker is placed in a blast drying oven at 120 °C to evaporate the solvent. The solid mixture is put into a quartz boat in a tube furnace. First, nitrogen is introduced for 30 minutes at a nitrogen flow rate of 200 mL / min, and then the temperature rising program is set to rise to 600 °C at a rate of 10 °C / min and maintained at 600 °C for carbonization for 2 h. After natural cooling, it is taken out. 0.6 g of the high-temperature carbonized biomass carbon is ground and put into a beaker, 40 mL of 2 mol / L hydrochloric acid is added, and it is stirred for 4 hours under the condition of water bath heating at 80 °C. The biomass carbon is washed to neutrality, filtered, and dried at 60 °C to obtain nitrogen-doped biochar.

[0057] Elemental analysis, BET, and XPS characterization analysis are carried out on the nitrogen-doped biochar. The XPS analysis spectrum is as Figure 1 shown, and the precise spectrum analysis results of N 1s are shown in Table 1.

[0058] The specific surface area of ​​biochar was determined to be 1155 m 2 / g, the average pore size is 2.81nm, the N content is 6.48%, and the nitrogen in the nitrogen-doped biochar exists in the forms of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen.

[0059] Table 1 N1s accurate spectrum analysis of nitrogen-doped biochar

[0060] Peak type Energy (eV) Chemical state Content, % N1s 398.33 Pyridine nitrogen 33.79 N1s 399.90 Pyrrole nitrogen 55.04 N1s 401.34 Graphitic nitrogen 11.17

[0061] Comparative Example 1

[0062] Put ZnCl2 and 2g of liquor lees in a beaker at a mass ratio of 2:1, add 15mL of deionized water and stir for 24h, and put the beaker into a blast oven at 120℃ to evaporate the solvent. Put the solid mixture into a quartz boat in a tube furnace, first pass nitrogen for 30 minutes, with a nitrogen flow rate of 200mL / min, then set the temperature program to 10℃ / min to 600℃, maintain 600℃, carbonize for 2h, and take it out after natural cooling. Grind 0.5g of high-temperature carbonized biochar and put it into a beaker, add 40mL of 2mol / L hydrochloric acid, stir for 4 hours under 80℃ water bath heating conditions, wash the biochar to neutrality, filter, and dry at 60℃.

[0063] The elemental analysis and BET characterization analysis of the biochar showed a specific surface area of ​​875 m 2 / g, and the N element content is 2.66%.

[0064] Example 2

[0065] 0.6 g of nitrogen-doped biochar obtained in Example 1 was used as a carrier, and 1.8 mL of 0.05 mol / L H2PtCl6 solution was added according to the mass ratio of Pt element to biochar of 3%. 10 mL of deionized water was added by equal volume impregnation method, and then fully stirred, allowed to stand for 24 h, and vacuum dried at 110 ° C for 10 h. The dried sample was placed in a tube furnace and heated to 300 ° C at a heating rate of 3 ° C / min. At this temperature, H2 was introduced for reduction for 2 h to obtain a Pt / N-BC catalyst with a Pt loading of 3%.

[0066] In a 250mL intermittent high-pressure reactor, 80mL of anhydrous ethanol, 10g of o-chloronitrobenzene, and 0.2g of Pt / N-BC catalyst were added in sequence. The reactor was sealed, and the air in the reactor was replaced with N2 and H2 for 5 times, and the hydrogen pressure was adjusted to 1MPa. At a speed of 200rpm, the temperature was raised to 60℃ at a heating rate of 10℃ / min, and the speed was adjusted to 750rpm. The reaction was carried out for 35min. After the reaction was completed and cooled to room temperature, the reactor was opened for sampling, and the catalyst was recovered by vacuum filtration. The filtrate was analyzed for the product composition by gas chromatography. The conversion rate of o-chloronitrobenzene reached 100%, and the selectivity of o-chloroaniline reached 99.31%.

[0067] Comparative Example 2

[0068] Wood charcoal (specific surface area of ​​1421m 2 / g, average pore size of 1.19nm) as a carrier, add H2PtCl6 solution according to the mass ratio of Pt element to wood charcoal of 3%, add the required deionized water by equal volume impregnation method, then add wood charcoal to the solution and stir well, let stand for 24h, and vacuum dry at 110℃ for 10h. The dried sample is placed in a tube furnace and heated to 300℃ at a heating rate of 3℃ / min. At this temperature, H2 is introduced for reduction for 2h to obtain Pt / C catalyst with a Pt loading of 3%.

[0069] In a 250mL intermittent high-pressure reactor, 80mL of anhydrous ethanol, 10g of o-chloronitrobenzene, and 0.2g of Pt / C catalyst were added in sequence. The reactor was sealed, and the air in the reactor was replaced with N2 and H2 for 5 times, and the hydrogen pressure was adjusted to 1MPa. The temperature was raised to 60°C at a heating rate of 10°C / min at a speed of 200rpm, and the speed was adjusted to 750rpm. The reaction was carried out for 35min. After the reaction was completed and cooled to room temperature, the reactor was opened for sampling, and the catalyst was recovered by vacuum filtration. The product composition of the filtrate was analyzed by gas chromatography. The conversion rate of o-chloronitrobenzene was 63.69%, and the selectivity of o-chloroaniline was 73.15%.

[0070] Example 3

[0071] 0.6 g of nitrogen-doped biochar obtained in Example 1 was used as a carrier, and 3.4 mL of 0.05 mol / L H2PdCl6 solution was added according to the mass ratio of Pd element to biochar of 3%. 10 mL of deionized water was added by equal volume impregnation method, and then fully stirred, left to stand for 24 h, and vacuum dried at 110 ° C for 10 h. The dried sample was placed in a tube furnace and heated to 300 ° C at a heating rate of 5 ° C / min. At this temperature, H2 was introduced for reduction for 2 h to obtain a Pd / N-BC catalyst with a Pd loading of 3%.

[0072] In a 250mL intermittent high-pressure reactor, 100mL of deionized water, 10g of 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS acid), and 0.2g of 3% Pd / N-BC catalyst were added in sequence, and the pH value of the solution was adjusted to 6.0 with 0.1mol / L dilute sulfuric acid. The reactor was sealed, and the air in the reactor was replaced with N2 and H2 for 5 times, and the hydrogen pressure was adjusted to 1MPa. At a speed of 200rpm, the temperature was raised to 60℃ at a heating rate of 10℃ / min, and the speed was adjusted to 750rpm. The reaction was carried out for 90min. After the reaction was completed and cooled to room temperature, the reactor was opened for sampling, and the catalyst was recovered by vacuum filtration. The product composition of the filtrate was analyzed by liquid chromatography. The conversion rate of DNS acid reached 100%, and the selectivity of DND acid reached 98.15%.

[0073] Comparative Example 3

[0074] Coal-based carbon (specific surface area of ​​782m 2 / g, average pore size of 1.87nm) as the carrier, add H2PdCl6 solution according to the mass ratio of Pd element to coal charcoal mass of 3%, add the required deionized water by equal volume impregnation method, then add the coal charcoal to the solution and stir it thoroughly, let it stand for 24h, and dry it in vacuum at 110℃ for 10h. The dried sample was loaded into a tube furnace and heated to 300℃ at a heating rate of 3℃ / min. At this temperature, H2 was introduced for reduction for 2h to obtain a Pd / C catalyst with a Pd loading of 3%.

[0075] In a 250mL intermittent high-pressure reactor, 100mL deionized water, 10g 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS acid), 0.2g 3% Pd / C catalyst were added in sequence, and the pH value of the solution was adjusted to 6.0 with 0.1mol / L dilute sulfuric acid. The reactor was sealed, and the air in the reactor was replaced with N2 and H2 for 5 times, and the hydrogen pressure was adjusted to 1MPa. At a speed of 200rpm, the temperature was raised to 60℃ at a heating rate of 10℃ / min, and the speed was adjusted to 750rpm. The reaction was carried out for 90min. After the reaction was completed and cooled to room temperature, the reactor was opened for sampling, and the catalyst was recovered by vacuum filtration. The product composition of the filtrate was analyzed by liquid chromatography. The conversion rate of DNS acid was 100%, and the selectivity of DND acid was 68.41%.

[0076] Example 4

[0077] The catalyst of Example 3 was filtered and reused for 20 cycles. The conversion rate of DNS acid was maintained at 100%, and the selectivity of DSD acid was maintained at more than 94.9%.

[0078] Comparative Example 4

[0079] Replace the carrier nitrogen-doped biochar in Example 3 with commercially available coconut shell charcoal, with a specific surface area of 1235 m 2 / g, an average pore diameter of 2.43 nm. Prepare a 3% Pd / AC catalyst in the same method and catalyze the hydrogenation reduction reaction of DNS acid to DSD acid under the same conditions. The conversion rate of DNS acid is 100%, and the selectivity of DND acid is 98.89%.

[0080] Filter the catalyst and reuse it. After 8 cycles of use, the selectivity of DSD drops from 98.89% to 35.94%.

[0081] It can be seen that the noble metal catalyst supported on commercially available activated carbon has a short cycle service life and is prone to deactivation, resulting in an increase in production costs.

[0082] Example 5

[0083] According to the method of Example 1, change the carbonization temperature to 400 °C and 700 °C respectively to prepare nitrogen-doped biochar-400 and nitrogen-doped biochar-700. Conduct elemental analysis on the prepared biochar. The nitrogen element content in nitrogen-doped biochar-400 is 9.09%, and the nitrogen element content in nitrogen-doped biochar-700 is 6.25%. Conduct XPS characterization analysis, and the contents of pyridine nitrogen, pyrrole nitrogen and graphitic nitrogen in the biochar are as shown in Table 2 below.

[0084] Table 2 Nitrogen existence forms of biochar at different carbonization temperatures

[0085] Content of each chemical state, 100% Nitrogen-doped biochar - 400 Nitrogen-doped biochar - 700 Pyridine nitrogen 22.75 13.12 Pyrrole nitrogen 58.96 78.01 Graphitic nitrogen 18.3 8.88

[0086] Example 6

[0087] Using nitrogen-doped biochar-400 and nitrogen-doped biochar-700 as carriers, load Pt according to the method of Example 2 to prepare 3% Pt / N-BC-400 and 3% Pt / N-BC-700 catalysts respectively. And evaluate the catalytic hydrogenation performance of the catalyst for o-chloronitrobenzene according to the method of Example 2. The results show that: the conversion rate of o-chloronitrobenzene by the 3% Pt / N-BC-400 catalyst is 100%, and the selectivity of o-chloroaniline is 84.45%; the conversion rate of o-chloronitrobenzene by the 3% Pt / N-BC-700 catalyst is 99.71%, and the selectivity of o-chloroaniline is 92.79%.

[0088] The results of Examples 5 and 6 show that different carbonization temperatures will affect the nitrogen element content and nitrogen existence form in the biochar after carbonization, and may further affect the catalytic performance of the noble metal-supported catalyst. The specific influence mechanism needs to be further studied. The present invention preferably selects a carbonization temperature of 600-700 °C, and the noble metal-supported catalyst obtained from the nitrogen-doped biochar has better catalytic performance. The optimal carbonization temperature is 600 °C.

Claims

1. A method for preparing nitrogen-doped biochar from yellow rice wine lees, characterized in that The method is as follows: The yellow rice wine lees are dried and crushed. The obtained lees powder and the activator are added to water, impregnated and then dried. Under a nitrogen atmosphere, they are calcined at a temperature of 400 - 800 °C for 1 - 3 h. The obtained carbonized lees are washed with dilute hydrochloric acid to obtain nitrogen-doped biochar.

2. The method according to claim 1, wherein The activator is one or more of ZnCl2, H3PO4, FeCl3, MnCl2, and H2SO4.

3. The method according to claim 1, characterized in that The mass ratio of the activator to the lees powder is 0.5 - 4:

1.

4. The method according to claim 1, wherein The temperature of the calcination is 600 - 700 °C.

5. The nitrogen-doped biochar prepared by the method according to any one of claims 1 - 4.

6. The nitrogen-doped biochar according to claim 5, wherein In the nitrogen-doped biochar, the nitrogen content is 6.0-10.0%, the existence forms of nitrogen element are pyrrole nitrogen, pyridine nitrogen and graphitic nitrogen, and the specific surface area of the nitrogen-doped biochar is 800-1200 m 2 / g.

7. A nitrogen-doped biochar-supported noble metal catalyst, wherein the nitrogen-doped biochar-supported noble metal catalyst uses the nitrogen-doped biochar according to claim 5 or 6 as a carrier and is loaded with an active component Pd or Pt, and the loading amount of the active component is 0.5 - 3.0%.

8. The application of the nitrogen-doped biochar-supported noble metal catalyst according to claim 7 in the selective hydrogenation reaction of nitroaromatic compounds.

9. The application according to claim 8, wherein The nitroaromatic compound is 4,4`-dinitrostilbene-2,2`-disulfonic acid or o-chloronitrobenzene, and 4,4'-diaminostilbene-2,2'-disulfonic acid or o-chloroaniline is prepared by the selective hydrogenation reaction.

10. The application according to claim 9, characterized in that The method of the application is as follows: 4,4`-dinitrostilbene-2,2`-disulfonic acid or o-chloronitrobenzene is dissolved in a solvent, the nitrogen-doped biochar-supported noble metal catalyst is added, and under a hydrogen pressure of 1 - 2 MPa, the temperature is raised to 40 - 90 °C for a selective hydrogenation reduction reaction. After the post-treatment of the reaction solution, 4,4'-diaminostilbene-2,2'-disulfonic acid or o-chloroaniline is respectively prepared, and the nitrogen-doped biochar-supported noble metal catalyst is recovered for recycling use.

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