A synthesis method and application of high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules

Abstract

The present invention provides a synthesis method and application of high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules. The synthesis method comprises the following steps: mixing a photocatalyst, a nitrogen-containing small molecule, and an electron donor, adding or not adding a co-catalyst, preparing a reaction solution, introducing an inert gas into the reaction solution and sealing it, and irradiating the reaction solution with visible light to obtain the high-value nitrogen-containing compound; wherein the nitrogen-containing small molecule comprises one or more of N2, NO, N2O, nitrate, and nitrite; and the photocatalyst comprises one or more of CdS, CdSe, ZnSe, CuInS2, CdSe / ZnS, CdSe / CdS, ZnSe / CdS, CdSe / ZnSe, CdS / ZnS, CdSe / CdS / ZnS, CdS / TiO2, and CdSe / TiO2. This synthesis method can utilize nitrogen-containing small molecules for efficient reduction to obtain high-value nitrogen-containing compounds such as NH3, urea or cyclohexanone oxime, and has high synthetic application value. At the same time, this synthesis method has mild reaction conditions, high visible light utilization rate, cheap and easily available raw materials, and strong applicability.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalysis technology, and specifically comprises a synthesis method and application of high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules. Background Art

[0002] Nitrogen-containing compounds play a wide range of irreplaceable roles in fertilizers, explosives, chemical fibers, and pharmaceutical molecules, possessing extremely high application value. For example, ammonia (NH3) is the second-largest chemical produced annually worldwide. It serves as the basis for the production of ammonium nitrogen fertilizers, nitric acid, urea, and a variety of nitrogen-containing organic compounds. It is also a green fuel, refrigerant, and hydrogen storage medium. Urea is also a widely used nitrogen fertilizer and a raw material for the production of urea-formaldehyde resin. Cyclohexanone oxime is a precursor for the production of nylon 6. However, the production of nitrogen-containing compounds reported so far often requires relatively demanding conditions. For example, NH3 is primarily synthesized via the Haber-Bosch process, using a reversible catalytic reaction of N2 and H2 at high temperatures (350-600°C) and pressures (100-200 atm). This process consumes 1.5% of the world's fossil energy and contributes 2.5% of global CO2 emissions. Urea is primarily synthesized using the Bosch-Meiser process, using a reversible reaction of NH3 and CO2 at temperatures of 150-200°C and pressures of 150-250 atm. The industrial synthesis of cyclohexanone oxime also relies on the reaction of cyclohexanone and hydroxylamine under heat and sulfuric acid. All of these industrial processes place extremely high demands on equipment, resulting in high pollution, high energy consumption, and high investment costs.

[0003] Photocatalysis can directly utilize inexhaustible solar energy, and use cheap and readily available nitrogen-containing small molecules and raw materials such as water, CO2, and organic biomass at room temperature and pressure to drive extremely challenging chemical reactions. It has the outstanding advantages of low energy consumption, low pollution, and low cost. Currently, there are two main technical routes for the synthesis of photocatalytic nitrogen-containing compounds: one is to directly use N2 as a substrate, usually using vacancies on the surface of the material (such as TiO2) or introducing metal sites such as iron and ruthenium to promote the chemical adsorption and activation of nitrogen molecules to synthesize compounds such as ammonia and urea. Due to the high bond energy of the nitrogen-nitrogen triple bond (N≡N) (941kJ mol -1 ) and is a non-polar bond, the reactivity and solubility of N2 are very poor (10 -4 -10 -3 mol L -1 ), so the quantum efficiency of existing photocatalytic materials and systems that directly use N2 to synthesize nitrogen-containing compounds is usually only 0.01%-1%, and the product concentration can only reach 0.2-2ppm. Such a low yield is not only far from practical synthetic applications, but also makes it difficult to accurately detect and analyze the product. Another path is to use nitrate or nitrite (NO x -) as substrates for the synthesis of nitrogen-containing compounds, which has unique advantages: 1) The bond energy of the NO bond is only 205 kJ mol -1 , easy to activate and highly reactive; 2) NO x - Generally very soluble in water (1-10 mol L -1 ), which is beneficial to accelerate mass transfer and improve reaction efficiency and selectivity; 3) NO x - The sources are wide, lightning, plasma discharge or high temperature can make N2 in the air react with O2 to form nitrogen oxides, which dissolve in water to produce NO x - , in addition NO x - Widely exists in industrial and agricultural wastewater and domestic sewage. Photocatalytic NO x - While achieving the treatment of nitrogen-containing wastewater and nitrogen oxide waste gas, reduction provides a more efficient way to synthesize nitrogen-containing compounds, which has the positive significance of "turning waste into treasure". In 2011, Takata et al. deposited CuPd nanoalloy on the surface of TiO2 and reduced nitrate to synthesize ammonia under ultraviolet light with a selectivity of 78% [J.Am.Chem.Soc.2011,133,1150]. In 2017, Hirai et al. found that the surface defects of TiO2 photocatalyst are conducive to NO3 - Selective conversion of NO to ammonia [ACS Catal. 2017, 7, 3713]. In 2022, Dong et al. introduced sub-nanosized alkaline earth metal co-catalysts into the surface of TiO2 nanosheets and achieved 0.78 mmol of photocatalytic NO3 in 72 hours of continuous illumination. - Reduction synthesis of ammonia [Nat. Commun. 2022, 13, 1098]. x - Although the synthesis of high-value nitrogen-containing compounds has begun to attract attention in recent years, existing photocatalysts and systems still have the following disadvantages: 1) Weak light absorption capacity. Most of the photocatalytic systems reported so far can only operate under ultraviolet light, and the utilization rate of the solar spectrum is insufficient (no more than 4%). 2) The conversion of small nitrogen-containing molecules to high-value nitrogen-containing compounds invariably undergoes a multi-electron and multi-proton process, involving the breaking of NO bonds and the formation of NH bonds and NC bonds. The existing system has low efficiency in photogenerated electron transfer and low efficiency in photocatalytic reactions, resulting in incomplete reactions, many side reactions, and poor selectivity. 3) Existing research is mostly limited to relatively low substrate concentrations (~100ppm), so the product concentration and absolute yield are very low, which is still a long way from synthetic application. Therefore, constructing a method for the efficient and highly selective photocatalytic reduction of small nitrogen-containing molecules to synthesize high-value nitrogen-containing compounds under visible light response has broad development prospects and research and application value. Summary of the Invention

[0004] To address the aforementioned issues with the prior art, one objective of the present invention is to provide a method for synthesizing high-value nitrogen-containing compounds through the photocatalytic reduction of small nitrogen-containing molecules. This method, under visible light irradiation, efficiently reduces small nitrogen-containing molecules to high-value nitrogen-containing compounds through the photocatalytic action of inorganic semiconductors composed of Group IIB-VIA elements. This method offers advantages such as mild reaction conditions, readily available and inexpensive raw materials, high visible light utilization, and high yield, demonstrating high application value.

[0005] Another object of the present invention is to provide a new application of the above-mentioned synthesis method in the synthesis of high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules.

[0006] To achieve the above first purpose, the technical solution adopted by the present invention includes:

[0007] The present invention discloses a method for synthesizing high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules, comprising the following steps:

[0008] A photocatalyst, a nitrogen-containing small molecule, and an electron donor are mixed, and a co-catalyst is added or not added to prepare a reaction solution, an inert gas is introduced into the reaction solution and the reaction solution is sealed, and the reaction solution is irradiated with visible light to obtain a high-value nitrogen-containing compound;

[0009] Wherein, the nitrogen-containing small molecules include one or more of N2, N2O, NO, nitrate and nitrite;

[0010] The photocatalyst includes one or more of CdS, CdSe, ZnSe, CuInS2, CdSe / ZnS, CdSe / CdS, ZnSe / CdS, CdSe / ZnSe, CdS / ZnS, CdSe / CdS / ZnS, CdS / TiO2 and CdSe / TiO2.

[0011] In one embodiment, the photocatalyst used in the present invention can be an inorganic semiconductor without ligands on the surface, or an inorganic semiconductor with inorganic ion ligands or organic ligands, wherein the inorganic ion ligands can be S 2- , HS - 、Se 2- 、HSe - OH - 、NO2 - or NO3 - Etc., for example, the photocatalyst may be S 2- -CdS, S 2--CdSe, etc.; the organic ligand can be tri-n-octylphosphine (oxygen), oleic acid, octadecylamine, 2-mercaptoacetic acid, 3-mercaptopropionic acid (MPA), 2-mercaptoethylamine, glutathione (GSH) or cysteine, etc. For example, the photocatalyst can be MPA-CdS, MPA-CdSe, GSH-CdS, GSH-CdSe, etc., and the inorganic ion ligand or organic ligand can be removed or changed by pretreatment according to actual needs.

[0012] Furthermore, the photocatalyst may be in the form of quantum dots, nanorods, nanosheets, or nanostructures and assemblies of other morphologies.

[0013] It is understood by those skilled in the art that the concentration of the photocatalyst in the reaction solution should be controlled within an appropriate range. If the concentration of the photocatalyst is too low, the photocatalytic efficiency is low, and if the concentration is too high, the light absorption capacity has reached saturation and the yield cannot be further increased. Therefore, it is preferably controlled within a range of 0.01-5.0 mg·mL -1 For example, the concentration of the photocatalyst in the reaction solution can be 0.01 mg mL -1 , 0.02mg mL -1 , 0.03mg mL -1 , 0.04mg mL -1 , 0.05mg mL -1 , 0.06mg mL -1 , 0.07mgmL -1 , 0.08mg mL -1 , 0.09mg mL -1 , 0.1mg mL -1 , 0.5mg mL -1 , 1mg mL -1 , 2mg mL -1 , 3mg mL -1 , 4mgmL -1 , 5mg mL -1 etc.

[0014] Furthermore, the nitrate and nitrite can exist stably at room temperature and are easily soluble in water. The nitrite includes but is not limited to one or more of LiNO2, NaNO2, KNO2 and tetrabutylammonium nitrite; the nitrate includes but is not limited to one or more of LiNO3, NaNO3, KNO3 and tetrabutylammonium nitrate.

[0015] In a specific embodiment, the source of nitrogen-containing small molecules can be commercially available chemicals, wastewater containing nitrates or nitrites, or a solution obtained by absorbing nitrogen oxides generated by air plasma discharge.

[0016] Furthermore, the concentration of the nitrogen-containing small molecule in the reaction solution is 10 -4 mol L -1 To saturation concentration. If the concentration of the nitrogen-containing small molecule is too low, the reaction will be interfered with by the side reaction of proton reduction and hydrogen production, resulting in low nitrogen-containing compound yield and poor selectivity. Therefore, the concentration of the nitrogen-containing small molecule in the reaction solution should be controlled. When the concentration of the nitrogen-containing small molecule is increased, the nitrogen-containing compound yield first increases and then reaches saturation. Beyond this concentration range, the nitrogen-containing compound has reached saturation, and further increasing the concentration is meaningless.

[0017] Furthermore, the electron donor includes but is not limited to one or more of sulfides, alcohol compounds, carboxylic acid compounds and thiol compounds; illustratively, the sulfide includes but is not limited to sodium sulfide, sodium hydrosulfide, etc.; the alcohol compound includes but is not limited to isopropyl alcohol, cyclohexanol, benzyl alcohol, phenylethyl alcohol, benzhydrol and its derivatives, etc.; the carboxylic acid compound includes but is not limited to ascorbic acid, sodium ascorbate, sodium lactate, etc.; the thiol compound includes but is not limited to thioglycolic acid, mercaptopropionic acid, mercaptoethylamine, thiophenol derivatives, glutathione, etc.

[0018] Furthermore, the concentration of the electron donor in the reaction solution is 10 -3 mol L -1 When the electron donor concentration is too low, the reaction rate is low and the yield of nitrogen-containing compounds is small. When the electron donor concentration is increased, the yield of nitrogen-containing compounds first increases and then reaches saturation. Beyond this concentration range, the nitrogen-containing compounds have reached saturation and it is meaningless to continue to increase the concentration.

[0019] Furthermore, the co-catalyst includes but is not limited to iron salts, cobalt salts, nickel salts, copper salts, molybdenum salts or metal complexes thereof.

[0020] Furthermore, the concentration of the co-catalyst in the reaction solution is 0-10 -3 mol L -1 When no co-catalyst is added, the synthesis of nitrogen-containing compounds can still proceed, but the reaction rate is generally low. When the co-catalyst concentration exceeds this range, the production of nitrogen-containing compounds reaches saturation, and further increasing the co-catalyst concentration is meaningless.

[0021] Furthermore, the light source of visible light is selected from one or more of LED, high pressure mercury lamp, simulated sunlight source, xenon lamp and sunlight.

[0022] Furthermore, the high-value nitrogen-containing compound includes but is not limited to one of NH3, urea and cyclohexanone oxime.

[0023] Furthermore, the inert gas includes but is not limited to one or more of helium, nitrogen and argon, preferably argon; the time for introducing the inert gas is 10-20 minutes to keep the reaction system in an inert gas environment.

[0024] Furthermore, the reaction can be carried out in a wide temperature range, as long as the components in the reaction solution do not solidify due to too low a temperature or vaporize due to too high a temperature. No special requirements are made here.

[0025] Furthermore, the visible light irradiation time is 1-100 hours, so that the nitrogen-containing compound produced during the reaction reaches a saturation concentration.

[0026] Furthermore, after the reaction is completed, a post-processing operation is also included to separate the reaction products, which can be achieved by extraction, distillation, and the like. For example, for NH3, its volatility under alkalinity or heating conditions can be utilized to separate it from the reaction solution by atmospheric distillation, reduced pressure distillation, or air flow purge, and then absorbed with acid and evaporated to obtain solid ammonium salts, such as ammonium chloride, ammonium bromide, and ammonium sulfate. For nitrogen-containing organic substances such as urea and cyclohexanone oxime, the reaction solution is extracted with dichloromethane, chloroform, or ethyl acetate, and the organic phase is collected, dried, concentrated, and recrystallized to obtain the product.

[0027] To achieve the above second purpose, the technical solutions adopted by the present invention include:

[0028] The present invention discloses an application of the above-mentioned synthesis method in synthesizing high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules.

[0029] Beneficial effects of the present invention:

[0030] The present invention discloses a method for synthesizing high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules. Compared with the existing technology, this synthesis method has the following advantages:

[0031] 1) This synthesis method can utilize nitrogen-containing small molecules (N2, NO, nitrate, nitrite) to efficiently reduce and obtain high-value nitrogen-containing compounds such as NH3, urea, and cyclohexanone oxime. It has high synthetic application value and provides an efficient path for the synthesis of high-value nitrogen-containing compounds using light energy.

[0032] 2) This synthesis method has mild reaction conditions, simple operation, high visible light utilization rate, cheap and readily available raw materials, and strong applicability.

[0033] 3) In the photocatalytic reduction of nitrogen-containing small molecules to synthesize ammonia, the ammonia production can reach gram levels, which is large and 1-3 orders of magnitude higher than the existing photocatalytic system.

[0034] 4) This synthetic method realizes NO for the first time x -The tandem photocatalytic conversion of cyclohexanone to cyclohexanone oxime has outstanding synthetic value.

[0035] 5) This synthesis method can utilize NO x - The wastewater is used as a reaction substrate to synthesize high-value nitrogen-containing compounds, realizing "turning waste into treasure".

[0036] 6) This method can use nitrogen oxides generated by air (N2, O2) plasma discharge as reaction substrates to synthesize high-value nitrogen-containing compounds, completing the cascade conversion from air to nitrogen-containing chemicals under mild conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] Figure 1 The ammonia production-illumination time curve using GSH-CdSe quantum dots for catalysis in Example 1 is shown.

[0039] Figure 2 The ammonia production-illumination time curve using GSH-CuInS2 quantum dots for catalysis in Example 2 is shown.

[0040] Figure 3 The ammonia production-illumination time curve using GSH-CdSe quantum dots for catalysis in Example 3 is shown.

[0041] Figure 4 Example 4 shows the use of S 2- -Ammonia production-light irradiation time curves catalyzed by CdS and ZnSe quantum dots.

[0042] Figure 5 The use of S in Example 5 is shown 2- -CdS quantum dots added with Fe 3+ Ammonia production-light exposure time curve of catalysis with co-catalyst.

[0043] Figure 6 The MPA-CdSe quantum dots were added to Fe in Example 6. 3+ Ammonia production-light exposure time curve of catalysis with co-catalyst.

[0044] Figure 7 The ZnSe@CdS nanorods (DOR) were added to the Co 2+ Ammonia production-light exposure time curve of catalysis with co-catalyst.

[0045] Figure 8 Example 8 shows the use of S 2- -Ammonia production-light irradiation time curve catalyzed by CdS quantum dots.

[0046] Figure 9 The ammonia production and illumination time curves using GSH-CdSe quantum dots for catalysis in Example 9 are shown.

[0047] Figure 10 The XRD pattern of ammonium chloride synthesized in Example 10 is shown.

[0048] Figure 11 The UV colorimetric identification results of the urea synthesized in Example 11 are shown;

[0049] Among them, the standard conditions are tested according to the conditions of Example 11, no KNO3 means no KNO3 solution is added, and other conditions are the same as the standard conditions.

[0050] Figure 12 The mass spectrum of cyclohexanone oxime synthesized in Example 12 is shown.

[0051] Figure 13 The mass spectrum of cyclohexanone oxime synthesized in Example 42 is shown. DETAILED DESCRIPTION

[0052] To more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. It should be understood that the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0053] It should be noted that the photocatalyst provided by the present invention can be prepared by referring to the published process. For example, taking the preparation of GSH-CdSe quantum dots as an example, the experimental steps are referred to the literature [Mater. Lett. 2006, 60, 3782.] with slight modifications:

[0054] ① Preparation of Na2SeO3 solution: 79.0 mg (1 mmol) of Se powder (200 mesh) and 378 mg (3 mmol) of Na2SO3 were weighed and dissolved in 200 mL of deionized water. Ar gas was introduced for 30 minutes to remove oxygen from the system. The mixture was then heated under reflux at 120°C for 3 hours under an argon atmosphere until the selenium powder was completely dissolved, yielding a clear, transparent Na2SeO3 solution. The solution was stored under an inert atmosphere and protected from light. ② Preparation of GSH-CdSe quantum dots: 74.0 mg (0.4 mmol) of CdCl2 was dissolved in 380 mL of deionized water. 184.5 mg (0.6 mmol) of glutathione was then added and stirred. After stirring, 10 mol / L NaOH solution was added dropwise to adjust the pH to 11.00-11.50. Ar gas was then introduced for 30 minutes. Then, 20 mL of the Na2SeO3 solution was rapidly injected. The mixture was heated under reflux at 120°C for 3.5 hours under an argon atmosphere to yield a yellow, transparent solution. The synthesis of other photocatalysts can be prepared by referring to the literature [Chem. Commun. 2018, 54, 4858-61; J. Am. Chem. Soc. 2021, 143, 18131-8; Adv. Mater. 2022, 34, 2106662.].

[0055] Example 1

[0056] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0057] 1) Add 1.00 mL of GSH-CdSe quantum dots (0.47 mg mL -1 );

[0058] 2) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0059] 3) Add 264 mg of ascorbic acid and 99 mg of sodium ascorbate to the solution of step 2, stir to completely dissolve, and adjust the volume to 5.00 mL to obtain a reaction solution;

[0060] 4) Flowing argon into the reaction solution for 10 min and sealing the Pyrex test tube;

[0061] 5) Irradiate the reaction solution with a 440nm LED light to cause a reaction.

[0062] Figure 1 The relationship between ammonia production and time is shown below. After 2 hours of reaction, 140 μmol of ammonia was obtained, and the conversion rate was 28%.

[0063] Example 2

[0064] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0065] 1) Add 10 mL of GSH-CuInS2 quantum dots (0.68 mg mL -1 );

[0066] 2) Add 505 mg of KNO3 solid;

[0067] 3) Add 2640 mg of ascorbic acid and 990 mg of sodium ascorbate, stir to completely dissolve, and dilute the solution to 50 mL to obtain a reaction solution;

[0068] 4) introducing argon gas into the reaction solution for 20 min and sealing the photoreactor;

[0069] 5) Irradiating the reaction solution with a solar simulator to cause a reaction;

[0070] 6) After 72 h of reaction, 1357 μmol of ammonia was obtained, with a conversion rate of 27%. NH3 in the mixed solution after the light-induced reaction was separated by distillation and treated with acid to obtain 142.4 mg of ammonium bromide.

[0071] Figure 2 is the relationship between ammonia production and time.

[0072] Example 3

[0073] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0074] 1) Add 7.5 mL of GSH-CdSe quantum dots (0.47 mg mL -1 );

[0075] 2) Add 5.0 mL of 0.5 mol L -1 NaNO2 solution;

[0076] 3) 10 mmol of 1-(4-methoxy)phenylethanol (1.22 g) was added to the solution in step 2 and the volume was adjusted to 75 mL to obtain a reaction solution;

[0077] 4) passing argon gas into the reaction solution for 10 minutes, and sealing the photoreactor;

[0078] 5) Irradiate the reaction solution with a 440nm LED light to cause a reaction;

[0079] 6) After 60 hours of reaction, 1807 μmol of ammonia was obtained from NO2 - The conversion rate to ammonia was 72%. The reaction mixture was extracted with dichloromethane, and NH3 in the mixture after the light-irradiation reaction was distilled from the aqueous phase to obtain 94 mg of ammonium chloride. The ammonium salt separation yield was 72%.

[0080] Figure 3 is the relationship between ammonia production and time.

[0081] Example 4

[0082] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0083] 1) Add 0.382 mL of S into the Pyrex tube. 2- -CdS quantum dots (0.27 mg mL -1 ) and 0.187 mL aqueous ZnSe quantum dots (0.42 mg mL -1 );

[0084] 2) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0085] 3) Add 1.00 mL of isopropanol to the solution in step 2, stir to completely dissolve, and dilute to 5.00 mL to obtain a reaction solution;

[0086] 4) Flowing argon into the reaction solution for 10 min and sealing the Pyrex test tube;

[0087] 5) Irradiate the reaction solution with a 440nm LED light to cause a reaction.

[0088] Figure 4 The relationship between ammonia production and time is shown in Figure 2. After 6 hours of reaction, 329 μmol of ammonia was obtained, with a conversion rate of 66%.

[0089] Example 5

[0090] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0091] 1) Add 0.20 mL of synthesized S into the Pyrex test tube. 2- -CdS quantum dots (0.27 mg mL -1 );

[0092] 2) Add 0.10 mL of 0.01 mol L -1 FeCl3 solution;

[0093] 3) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0094] 4) Add 1.00 mL of isopropanol to the solution in step 3, and dilute to 5.00 mL with water to obtain a reaction solution;

[0095] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0096] 6) Irradiate the reaction solution with a 440nm LED light to cause a reaction.

[0097] Figure 5 The relationship between ammonia production and time is shown in Figure 2. After 2 hours of reaction, 387 μmol of ammonia was obtained, with a conversion rate of 77%.

[0098] Example 6

[0099] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0100] 1) Add 1.00 mL of MPA-CdSe quantum dots (0.31 mg mL -1 );

[0101] 2) Add 0.10 mL of 0.01 mol L -1 FeCl3 solution, stir until it is completely dissolved;

[0102] 3) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0103] 4) Add 1.00 mL of isopropanol and dilute to 5.00 mL with deionized water to obtain a reaction solution;

[0104] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0105] 6) Irradiate the reaction solution with a 440nm LED light to cause a reaction.

[0106] Figure 6 The relationship between ammonia production and time is shown in Figure 2. After 8 hours of reaction, 498 μmol of ammonia was obtained, with a conversion rate of 99%.

[0107] Example 7

[0108] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0109] 1) Add 1.17 mL of ZnSe@CdS nanorods (0.63 mg mL -1 );

[0110] 2) Add 0.10 mL of 0.01 mol L -1 CoCl2 solution, stir until completely dissolved;

[0111] 3) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0112] 4) Add 1.00 mL of isopropanol and dilute to 5.00 mL with deionized water to obtain a reaction solution;

[0113] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0114] 6) Irradiate the reaction solution with a 440nm LED light to cause a reaction.

[0115] Figure 7 The relationship between ammonia production and time is shown in Figure 2. After 8 hours of reaction, 147 μmol of ammonia was obtained, with a conversion rate of 30%.

[0116] Example 8

[0117] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0118] 1) Add 20 mL of S into the photoreactor 2- -CdS quantum dots (0.27 mg mL -1 );

[0119] 2) Add 15 mL of 1.4 mol L -1 Nitrate wastewater (containing 10 -3 mol L -1 Fe);

[0120] 3) Add 40 mL of isopropyl alcohol to the wastewater in step 2, and add deionized water to make the volume to 230 mL to obtain a reaction solution;

[0121] 4) passing argon gas into the reaction solution for 10 minutes, and sealing the photoreactor;

[0122] 5) Irradiate the reaction solution with a 440nm LED light to cause a reaction. Figure 8 is the relationship between ammonia production and time;

[0123] 6) After 96 h of reaction, 15440 μmol of ammonia was obtained, with a conversion rate of 67%. NH3 in the reaction mixture was separated by aeration, and 1001 mg of ammonium sulfate was obtained after acid treatment. The recovery rate of nitrogen in the wastewater was 66%.

[0124] Example 9

[0125] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0126] 1) Add 4 mL of GSH-CdSe quantum dots (0.47 mg mL -1 );

[0127] 2) Add 10 mL of nitrogen oxides produced by absorbing air spark discharge to obtain NOx - Solution (containing 58.3mmolL -1 NO2 - and 0.9 mmol L -1 NO3 - );

[0128] 3) Add 5 mmol 1-phenylethanol (610 mg), stir to completely dissolve, and add deionized water to make the volume 20 mL to obtain a reaction solution;

[0129] 4) passing argon gas into the reaction solution for 10 minutes, and sealing the photoreactor;

[0130] 5) Irradiate the reaction solution with a 440nm LED light to cause a reaction. Figure 9 is the relationship between ammonia production and time;

[0131] 6) After 10 h of illumination, 492 μmol of ammonia was obtained with a conversion rate of 83%. NH3 in the mixed solution after the illumination reaction was separated by distillation and 25.7 mg of ammonium chloride was obtained after acid treatment.

[0132] Example 10

[0133] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0134] 1) Add 15 mL of CdSe / CdS quantum dots (0.54 mg mL -1 );

[0135] 2) Add 4 mL of 10 mmol L -1 CoCl2 solution;

[0136] 3) Add 15 mL of 0.5 mol L -1 KNO3 solution;

[0137] 4) Add 40 mL of isopropanol and dilute to 150 mL with deionized water to obtain a reaction solution;

[0138] 5) passing argon gas into the reaction solution for 10 minutes, and sealing the photoreactor;

[0139] 6) Irradiating the reaction solution with a solar simulator to cause a reaction;

[0140] 7) Irradiation for 57 h yielded 2580 μmol of ammonia with a conversion rate of 35%. NH3 in the mixed solution after the irradiation reaction was separated by distillation and 129 mg of ammonium chloride was obtained after acid treatment. Its XRD results are as follows: Figure 10 shown.

[0141] Example 11

[0142] A method for synthesizing urea using visible light catalysis, comprising the following steps:

[0143] 1) Add 1.00 mL of GSH-CdSe quantum dots (0.47 mg mL -1 );

[0144] 2) Add 1 mL of 0.5 mol L -1 KNO3 solution;

[0145] 3) Add 80 mg of glutathione to the solution in step 2, and add deionized water to make the volume 5.00 mL to obtain a reaction solution;

[0146] 4) Flowing argon into the reaction solution for 10 min and sealing the Pyrex test tube;

[0147] 5) Irradiate the reaction solution with a 440nm LED lamp for 6 hours to allow it to react fully.

[0148] In this example, 30 μmol of urea was obtained, and the conversion rate was 6%. Figure 11 This is the UV colorimetric identification result of the obtained urea.

[0149] Example 12

[0150] A method for synthesizing cyclohexanone oxime using visible light catalysis, comprising the following steps:

[0151] 1) Add 0.50 mL of MPA-CdS quantum dots (1.13 mg mL -1 );

[0152] 2) Add 34.5 mg of NaNO2;

[0153] 3) Dissolve 0.40 mL of cyclohexanol in 0.60 mL of acetonitrile and add to the above solution;

[0154] 4) Adjust the pH of the system to 12 with NaOH, add deionized water to make the volume to 5.00 mL, and obtain a reaction solution;

[0155] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0156] 6) Irradiate the reaction solution with a 440nm LED lamp for 24 hours to allow it to react fully.

[0157] In this example, 216 μmol of cyclohexanone oxime was obtained with a conversion rate of 43%. The mass spectrum thereof is shown in FIG. Figure 12 .

[0158] Example 13

[0159] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0160] 1) Add 0.50 mL of CdSe / ZnS quantum dots (0.54 mg mL -1 );

[0161] 2) Add 0.10 mL of 10 mmol L -1 NiCl2 solution;

[0162] 3) Add 1 mL of 0.5 mol L -1 KNO3 solution;

[0163] 4) Add 1.00 mL of isopropanol to the solution in step 3, and add deionized water to make the volume 5.00 mL to obtain a reaction solution;

[0164] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0165] 6) Irradiate the reaction solution with a 440nm LED light for 4 hours to allow it to react fully.

[0166] In this example, 242 μmol of ammonia was obtained, and the conversion rate was 48%.

[0167] Examples 14-17

[0168] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0169] 1) Add 0.20 mL of S into the Pyrex tube. 2- -CdS quantum dots (0.27 mg mL -1 );

[0170] 2) Add 0.10 mL of 10 mmol L -1 Cobalt oxime cocatalyst (see Table 1) solution;

[0171] 3) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0172] 4) Add 1.00 mL of isopropanol to the solution in step 3, and add deionized water to make the volume 5.00 mL to obtain a reaction solution;

[0173] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0174] 6) Irradiate the reaction solution with a 440nm LED light for 4 hours to allow it to react fully.

[0175] Table 1 Ammonia yield and conversion rate obtained using different cobalt oxime co-catalysts in Examples 14-17

[0176] Example No. Cobalt oxime promoter types Ammonia production (μmol) Conversion rate (%) 14 Dichlorocobaloxime 188 38 15 Chloro(pyridine)cobalt oxime 181 36 16 Chloro(4-mercaptopyridine)cobalt oxime 156 31 17 Chloro(4,4'-methylbipyridyl)cobalt oxime 203 41

[0177] Example 18

[0178] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0179] 1) Add 0.20 mL of S into the Pyrex tube. 2- -CdS quantum dots (0.27 mg mL -1 );

[0180] 2) Add 0.10 mL of 10 mmol L -1 CoCl2 solution;

[0181] 3) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0182] 4) Add 1.00 mL of 65% sodium lactate solution to the solution in step 3, stir to completely dissolve, and add deionized water to make the volume 5.00 mL to obtain a reaction solution;

[0183] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0184] 6) Irradiate the reaction solution with a 440 nm LED lamp for 16 h to allow for full reaction.

[0185] In this example, 140 μmol of ammonia was obtained, and the conversion rate was 28%.

[0186] Examples 19-26

[0187] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0188] 1) Add 1.00 mL of GSH-CdSe quantum dots (0.47 mg mL -1 );

[0189] 2) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0190] 3) Add 1 mmol of a 1-aryl alcohol derivative (see Table 2) to the solution of step 2, stir to completely dissolve, and add deionized water to make the volume 5.00 mL to obtain a reaction solution;

[0191] 4) Flowing argon into the reaction solution for 10 min and sealing the Pyrex test tube;

[0192] 5) Irradiate the reaction solution with a 440nm LED lamp for 24 hours to allow it to react fully.

[0193] Table 2 Ammonia production, conversion rate and yield of aromatic aldehydes and ketones obtained using different 1-aryl alcohol derivatives in Examples 19-26

[0194]

[0195] Table 2 shows that 1-aryl alcohol derivatives can serve as electron donors for the photocatalytic synthesis of ammonia. It is worth noting that, while producing ammonia, the 1-aryl alcohols shown in Table 2 are selectively oxidized to the corresponding aryl aldehydes / ketones, with the yields of aryl aldehydes / ketones shown in Table 2. This demonstrates that the electron donors involved in the present invention can serve as substrates for organic oxidation reactions, thereby simultaneously producing ammonia and high-value oxidation products.

[0196] Example 27

[0197] A method for synthesizing ammonia using visible light catalysis, comprising the following steps:

[0198] 1) At pH = 10, 1.00 mL of MPA-CdSe quantum dots (0.31 mg mL -1 ) was mixed with 0.5 mg P25-TiO2 and ultrasonically dispersed for 10 min, and then added to a Pyrex test tube;

[0199] 2) Add 0.10 mL of 10 mmol L -1 FeCl3 solution;

[0200] 3) Add 1.00 mL of 0.5 mol L -1 KNO3 solution;

[0201] 4) Add 1.00 mL of isopropanol to the solution in step 3, stir to completely dissolve, and add deionized water to make the volume 5.00 mL to obtain a reaction solution;

[0202] 5) Purify the reaction solution with argon for 10 min and seal the Pyrex test tube;

[0203] 6) Irradiate the reaction solution with a 440nm LED lamp for 8 hours to allow it to react fully.

[0204] In this example, 254 μmol of ammonia was obtained, and the conversion rate was 51%.

[0205] Example 28

[0206] The experimental method was the same as that in Example 1, except that GSH-CdSe quantum dots were replaced with MPA-CdSe quantum dots. Other conditions were the same as in Example 1. After 2 h of reaction, 86 μmol of ammonia was obtained, with a conversion rate of 17%.

[0207] Example 29

[0208] The experimental method was the same as that in Example 1, except that the quantum dot surface ligand was replaced with 1-mercaptoethylamine. Other conditions were the same as in Example 1. After 2 h of reaction, 114 μmol of ammonia was obtained, and the conversion rate was 23%.

[0209] Example 30

[0210] The experimental method is the same as that of Example 4, except that S 2- -The combination of CdS quantum dots and ZnSe quantum dots is replaced by S 2- - Combination of CdSe quantum dots and ZnSe quantum dots. Other conditions were the same as those in Example 4. After 4 h of reaction, 47 μmol of ammonia was obtained, with a conversion rate of 10%.

[0211] Example 31

[0212] The experimental method was the same as that in Example 5, except that FeCl3 was replaced by CoCl2. Other conditions were the same as in Example 5. After 2 h of reaction, 346 μmol of ammonia was obtained, and the conversion rate was 69%.

[0213] Example 32

[0214] The experimental method was the same as that in Example 5, except that FeCl3 was replaced by NiCl2. Other conditions were the same as in Example 5. After 2 h of reaction, 322 μmol of ammonia was obtained, and the conversion rate was 64%.

[0215] Example 33

[0216] The experimental method was the same as that in Example 5, except that FeCl 3 was replaced by ZnCl 2 . Other conditions were the same as in Example 5. After 2 h of reaction, 176 μmol of ammonia was obtained, and the conversion rate was 35%.

[0217] Example 34

[0218] The experimental method was the same as that in Example 5, except that FeCl3 was replaced by CuCl2. Other conditions were the same as in Example 5. After 2 h of reaction, 74 μmol of ammonia was obtained, and the conversion rate was 15%.

[0219] Example 35

[0220] The experimental method was the same as that in Example 5, except that FeCl 3 was replaced by Na 2 MoO 4 . Other conditions were the same as those in Example 5. After reacting for 2 h, 58 μmol of ammonia was obtained, and the conversion rate was 12%.

[0221] Example 36

[0222] The experimental method is the same as that of Example 5, except that S 2- -CdSe quantum dots were replaced with CdSe / ZnS quantum dots. Other conditions were the same as those in Example 5. After 4 h of reaction, 197 μmol of ammonia was obtained, with a conversion rate of 40%.

[0223] Example 37

[0224] The experimental method was the same as that in Example 5, except that isopropyl alcohol was replaced by benzyl alcohol. Other conditions were the same as those in Example 5. After reacting for 4 h, 500 μmol of ammonia was obtained, and the conversion rate was 100%.

[0225] Example 38

[0226] The experimental method was the same as that in Example 5, except that KNO 3 was replaced by NaNO 2 . Other conditions were the same as those in Example 5. After 4 h of reaction, 334 μmol of ammonia was obtained, and the conversion rate was 69%.

[0227] Example 39

[0228] The experimental method was the same as that in Example 6, except that the amount of each component in the reaction system was increased by 90 times. Other conditions were the same as those in Example 6. After 96 hours of reaction, 43,400 μmol of ammonia was obtained, and the conversion rate was 96%.

[0229] Example 40

[0230] The experimental method was the same as that of Example 9, except that GSH-CdSe quantum dots were replaced with MPA-CdSe quantum dots and 2 mL of 10 mmol L -1 FeCl3, and the amounts of other components were increased by 20 times. Other conditions were the same as those in Example 9. After 36 hours of reaction, 5740 μmol of ammonia was obtained, and the conversion rate was 79%.

[0231] Example 41

[0232] The experimental method was the same as that of Example 7, except that the 440 nm LED lamp was replaced with sunlight. Other conditions were the same as those of Example 7. After 12 h of reaction, 99 μmol of ammonia was finally obtained, with a conversion rate of 20%.

[0233] Example 42

[0234] The experimental method is the same as that of Example 12, except that 0.1M 15 NO2 - replace 14 NO2 - , other conditions are the same as those in Example 12, and the reaction is carried out for 24 hours to obtain15 N-labeled cyclohexanone oxime 107 μmol, conversion rate 21%, its mass spectrum is as follows Figure 13 .

[0235] Example 43

[0236] The experimental method was the same as that in Example 12, except that 0.1 M KNO 3 was used instead of NaNO 2 . Other conditions were the same as those in Example 12. After 24 h of reaction, 86 μmol of cyclohexanone oxime was obtained, with a conversion rate of 17%.

[0237] Example 44

[0238] The experimental method was the same as that of Example 12, except that 0.40 mL of KA oil (cyclohexanol and cyclohexanone volume ratio of 5:3) was used instead of cyclohexanol. Other conditions were the same as those of Example 12. After 24 h of reaction, 206 μmol of cyclohexanone oxime was obtained. - The conversion to cyclohexanone oxime was 41%.

[0239] Example 45

[0240] The experimental method was the same as that in Example 27, except that the MPA-CdSe quantum dots were replaced with MPA-CdS quantum dots of the same mass concentration. Other conditions remained unchanged. After 8 h of reaction, 354 μmol of ammonia was obtained, and the conversion rate was 71%.

[0241] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for synthesizing high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules, characterized in that: The steps include: A photocatalyst, a nitrogen-containing small molecule, and an electron donor are mixed, and a co-catalyst is added or not added to prepare a reaction solution, an inert gas is introduced into the reaction solution and the reaction solution is sealed, and the reaction solution is irradiated with visible light to obtain a high-value nitrogen-containing compound; Wherein, the nitrogen-containing small molecules include one or more of N2, NO, N2O, nitrate and nitrite; The photocatalyst includes one or more of CdS, CdSe, CuInS2, CdSe / ZnS, CdSe / CdS, and ZnSe / CdS; The surface of the photocatalyst has no ligands and contains inorganic ion ligands or organic ligands; the inorganic ion ligands are selected from S 2- , HS - 、Se 2- 、HSe - OH - 、NO2 - or NO3 - , the organic ligand is selected from tri-n-octylphosphine, tri-n-octylphosphine oxide, oleic acid, octadecylamine, 2-mercaptoacetic acid, 3-mercaptopropionic acid, 2-mercaptoethylamine, glutathione or cysteine; The photocatalyst has a nanostructure of quantum dots, nanorods or nanosheets; The electron donor comprises one or more of sulfide, alcohol compound, carboxylic acid compound and sulfhydryl compound; the sulfide is selected from sodium sulfide or sodium hydrosulfide; the alcohol compound is selected from isopropyl alcohol, cyclohexanol, benzyl alcohol, phenylethyl alcohol or benzhydrol; the carboxylic acid compound is selected from ascorbic acid, sodium ascorbate or sodium lactate; the sulfhydryl compound is selected from thioglycolic acid, mercaptopropionic acid, mercaptoethylamine or glutathione; The co-catalyst is selected from iron salts, cobalt salts, nickel salts, copper salts, molybdenum salts or metal complexes thereof; The concentration of the co-catalyst in the reaction solution is 0-10 -3 mol L -1 ; The high-value nitrogen-containing compound includes urea or cyclohexanone oxime.

2. The synthesis method according to claim 1, wherein The concentration of the photocatalyst in the reaction solution is 0.01-5.0 mg mL -1 .

3. The synthesis method according to claim 1, wherein The nitrite is selected from one or more of LiNO2, NaNO2, KNO2 and tetrabutylammonium nitrite; The nitrate is selected from one or more of LiNO3, NaNO3, KNO3 and tetrabutylammonium nitrate.

4. The synthesis method according to claim 1, characterized in that The concentration of the nitrogen-containing small molecule in the reaction solution is 10 -4 mol L -1 to saturation concentration.

5. The synthesis method according to claim 1, characterized in that The concentration of the electron donor in the reaction solution is 10 -3 mol L -1 to saturation concentration.

6. The synthesis method according to claim 1, characterized in that The light source of the visible light is selected from one or more of LED, high pressure mercury lamp, simulated sunlight source, xenon lamp and sunlight.

7. The synthesis method according to claim 1, characterized in that The time of introducing inert gas is 10-20 min.

8. The synthesis method according to claim 1, characterized in that The visible light irradiation time is 1-100 h, so that the nitrogen-containing compound produced during the reaction reaches a saturation concentration.

9. Use of the synthesis method according to any one of claims 1 to 8 in the synthesis of high-value nitrogen-containing compounds by photocatalytic reduction of nitrogen-containing small molecules.

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