Floating relay catalyst for producing agricultural nitrogen fertilizer, preparation method and application

Abstract

The present invention discloses a floating relay catalyst for producing agricultural nitrogen fertilizer, comprising a CC carrier and a Bi / TiO2 photocatalyst, wherein the photocatalyst is distributed on the surface of the CC carrier. The present invention also discloses a method for preparing the catalyst, wherein titanium dioxide, bismuth trichloride and anhydrous ethanol are used as raw materials, a Bi / TiO2 material is prepared by a one-step photoreduction method, and then the Bi / TiO2 material is ultrasonically dispersed in a Nafion / ethanol solution, and the Bi / TiO2 material is loaded on a photothermal material CC carrier by a coating method to obtain a floating Bi / TiO2 / CC relay catalyst; the catalyst of the present invention is applied in crop planting, which not only cleverly solves the problem of insufficient supply of N2 reactants in the traditional photocatalytic ammonia synthesis powder system, but also activates N2 based on the TiO2 full nitrogen fixation technology, and converts the nitrate product into ammonia by Bi relay catalysis, thereby promoting the enhancement of the performance of photocatalytic ammonia synthesis.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts for liquid nitrogen fertilizers, and in particular relates to a floating relay catalyst for producing agricultural nitrogen fertilizers, and also relates to a preparation method and application of the floating relay catalyst for producing agricultural nitrogen fertilizers. Background Art

[0002] Nitrogen fertilizer is the most produced and used fertilizer in the world, and plays an important role in increasing crop yields and improving the quality of agricultural products. However, traditional nitrate-ammonium nitrogen fertilizers, amide nitrogen fertilizers, and cyanamide nitrogen fertilizers all have problems such as poor heat exchange effect of the synthesis device, low ammonia condensation efficiency, high energy consumption, high carbon emissions, and environmental pollution caused by wastewater and waste gas generated during the preparation process. Therefore, it is urgent to develop a new type of nitrogen fertilizer that is low-cost and environmentally friendly, has a high nitrogen utilization rate, is efficient and energy-efficient in the development process, is pollution-free, and takes into account fertilizer benefits, economic benefits, and environmental benefits.

[0003] In recent years, photocatalytic N 2 and H 2 O reaction to generate ammonia has become a hot topic among researchers because of its advantages such as using renewable solar energy, zero carbon emissions, mild reaction conditions and flexible equipment. However, there has never been any research on the use of photocatalytic generation of ammonia, nitrogen fixation in water to obtain new nitrogen fertilizers, and its effects on crop growth, physiology, yield and quality. 2 Problems such as insufficient supply of reactants and insufficient activation capacity result in low efficiency of ammonia synthesis. Therefore, how to reasonably construct a catalytic system, efficiently synthesize ammonia, and prepare new green nitrogen fertilizers is a hot issue that needs to be solved urgently. So far, researchers have mainly focused on preparing efficient photocatalysts to improve the performance of ammonia synthesis, but there is little research on photocatalytic reaction systems. In fact, replacing H 2 Becoming a proton source can undoubtedly greatly improve economics and environmental protection, but the use of liquid water has also become a major factor limiting the further improvement of photocatalytic performance. First, due to the 2 The molecules have extremely low solubility and slow diffusion rate in water, which limits the N 2 The transfer of molecules to the catalyst surface. Secondly, high temperature promotes the activation of N≡N bonds, while the large specific heat capacity of water is not conducive to the formation of a high-temperature reaction system.

[0004] Floating materials are based on photocatalysts as the core and lightweight materials as the carrier. They can float on the gas-liquid interface, which can not only ensure the sufficient supply of gaseous reactants during the reaction, but also make full use of solar energy, improve the utilization rate of solar energy, and obtain enhanced photocatalytic reaction activity. Therefore, by rationally designing floating catalysts and making full use of their advantages, the efficiency of photocatalytic ammonia synthesis will undoubtedly be greatly improved. More importantly, the system has the characteristics of low cost and unlimited expansion, which makes it easier to realize its large-scale practical application.

[0005] As an ideal semiconductor catalyst, titanium dioxide has the characteristics of good light stability, high efficiency, good conductivity, non-toxicity and low cost. Due to its strong redox ability, it can efficiently promote N 2 Molecular activation is widely used in the field of photocatalytic nitrogen fixation to produce ammonia and nitrate. Bismuth, as a non-precious metal plasma, has similar properties to precious metals such as Au, Ag, and Pd, and also has significant advantages such as being cheap, easy to obtain, and abundant in reserves. Combining it with other catalysts can not only enhance the photoreduction activity of electrons, but also broaden the light response range and improve the efficiency of photogenerated charge separation. More importantly, it is reported that the hot electrons generated by the plasma can convert the non-volatile nitrate products that easily occupy the reactive active sites of floating materials into volatile ammonia products, allowing the system to maintain good stability. In addition, carbon cloth (CC), as a lightweight photothermal material, is an excellent carrier candidate in floating material systems, especially for the study of photocatalytic ammonia synthesis reactions. The photothermal energy generated by it can create a favorable high-temperature reaction environment to promote N 2 The activation of the reactant molecules can further improve the performance of photocatalytic ammonia synthesis. 2 —Bi—CC are combined to construct a floating relay catalyst system for the production of agricultural nitrogen fertilizer in order to obtain improved photocatalytic nitrogen fixation performance, and then prepare a new type of liquid nitrogen fertilizer at low cost and high efficiency and explore its impact on the actual growth of crops, providing a scientific basis for the development of low-cost, environmentally friendly and high-efficiency nitrogen fertilizers in my country, which is of profound significance for improving fertilizer utilization, reducing nitrogen leaching and improving crop yield and quality. Summary of the invention

[0006] The object of the present invention is to provide a floating relay catalyst for producing agricultural nitrogen fertilizer.

[0007] The present invention also aims to provide a method for preparing a floating relay catalyst for producing agricultural nitrogen fertilizer, thereby solving the problem of weak activation ability of traditional photocatalysts.

[0008] The present invention also aims to provide the application of the floating relay catalyst in producing agricultural nitrogen fertilizer.

[0009] The first technical solution adopted by the present invention is: a floating relay catalyst for producing agricultural nitrogen fertilizer, the relay catalyst comprising a CC carrier and Bi / TiO 2 Photocatalyst, Bi / TiO 2 The photocatalyst is distributed on the surface of CC support; Bi is relatively 2 The molar ratio of Bi / TiO is 0-2; 2 The loading amount on CC carrier is 0.01~5g / cm 2 .

[0010] The second technical solution adopted by the present invention is: a preparation method of a floating relay catalyst for producing agricultural nitrogen fertilizer, firstly using TiO 2 Bi / TiO2, which is responsive to visible light and has high separation efficiency of photogenerated electron-hole pairs, was prepared by a one-step photodeposition process using (P25) and bismuth trichloride as raw materials and ethanol as solvent. 2 The catalyst is then ultrasonically dispersed in a perfluorosulfonic acid polymer solution Nafion or an ethanol solution, and the Bi / TiO 2 Loaded on CC carrier, floating Bi / TiO 2 / CC relay catalyst.

[0011] The present invention is also characterized in that:

[0012] Furthermore, the above preparation method comprises the following steps:

[0013] Step 1: Weigh bismuth trichloride, place it in anhydrous ethanol, and stir it at room temperature for 0.5 to 1.0 h until it is completely dissolved to obtain solution A;

[0014] Step 2: Weigh TiO 2 Place it in solution A, stir and mix for 0.5-1.0h, then transfer it to a sealed quartz reactor, continue to introduce argon for 30-60min, and then at 50-150mW cm -2 The light reaction under the xenon lamp with the light intensity is 0.5 to 1.5 hours;

[0015] Step 3: After the reaction is completed, the solution is cooled to room temperature, the precipitate is separated by a centrifuge, washed with anhydrous ethanol for 3 to 4 times, and then dried under vacuum conditions at 50 to 70 ° C to obtain Bi / TiO 2 catalyst;

[0016] Step 4: Weigh Bi / TiO 2 The catalyst is placed in a 0.5-1.0% perfluorosulfonic acid polymer solution / ethanol solution, and after ultrasonic mixing for 0.5-2 hours, the mixed solution is loaded on a 2×2-100×100 cm 2The floating Bi / TiO 2 / CC relay catalyst.

[0017] In step 1, the ratio of bismuth trichloride to anhydrous ethanol is 0-0.8 g: 50-100 mL.

[0018] The bismuth trichloride in step 1 and the TiO 2 The mass ratio of is 0~8:1~2.

[0019] Step 4 Bi / TiO 2 The ratio of the catalyst to the perfluorosulfonic acid type polymer solution is 0.01-5 g: 0.2-100 mL.

[0020] The present invention also provides the use of the above floating relay catalyst for producing agricultural nitrogen fertilizer, wherein the floating Bi / TiO 2 / CC catalyst obtains nitrogen fixation products through photocatalytic nitrogen fixation reaction and directly irrigates the crop growth cycle;

[0021] Specifically, the performance evaluation method is as follows: a 300W xenon lamp is used as the simulated sunlight light source, a customized sealed quartz reactor is used, 20-100mL deionized water is used as the proton source, and Bi / TiO 2 / CC catalyst system floats on the surface of liquid water. Before irradiation, nitrogen is introduced into the sealed reactor for 30 to 60 minutes to remove impurities adsorbed on the catalyst surface and exhaust the air in the reactor. After 0.5 to 5 hours of light irradiation, 5 mL of solution is taken from the reactor respectively to quantitatively analyze the concentrations of ammonia and nitrate products. The absorbance is measured by UV-visible spectrophotometer, wherein the concentration of ammonia product is calculated based on the characteristic absorption peak at 420 nm of Nessler's reagent method; under the condition of adding 0.1 mL 1M HCl and 0.01 mL 0.8 wt% aminosulfonic acid solution, the absorbance measured at 220 nm and 275 nm (A=A 220 nm -2A 275 nm ) to calculate the nitrate product concentration and thus determine the Bi / TiO 2 Photocatalytic nitrogen fixation performance and reaction mechanism of / CC catalyst system.

[0022] The application conditions in crop planting are: floating Bi / TiO 2The product solution produced by the photocatalytic nitrogen fixation reaction of the / CC catalyst system is directly applied to the planting of lettuce crops. After planting, 20 to 50 mL of the nitrogen fixation product solution is added to each lettuce crop every 1 to 3 days, and the growth and physiological related indicators of lettuce are measured, including plant height, stem diameter, maximum leaf area, root system parameters (total root length, total root surface area, total root volume and average root diameter, etc.), color difference, relative chlorophyll content, photosynthetic parameters (net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration and transpiration rate, etc.), etc., and the yield and quality related indicators of lettuce are measured during the harvest period, including weight (fresh weight and dry weight), vitamin C, soluble sugar and soluble protein content, etc.

[0023] The floating Bi / TiO 2 / CC relay catalyst not only solves the problem of N 2 The problem of insufficient supply of reactants and the TiO-based 2 The complete nitrogen fixation reaction that can occur in the components and the photothermal energy generated by the CC carrier of the photothermal material can be used to fix N 2 The molecules are activated, and the hot electrons generated by the plasma Bi undergo a relay catalytic process, reducing the non-volatile nitrate products to volatile ammonia products, making the floating Bi / TiO 2 The / CC catalyst system has good stability, thereby improving the performance of synthetic ammonia and realizing its application in crop planting. This research has great practical significance, but has not yet attracted attention in the field of photocatalysis. The present invention aims to provide an economical and environmentally friendly photocatalyst system that can promote the activity of synthetic ammonia and has a simple composition, so as to achieve the purpose of efficient photocatalytic synthesis of ammonia and can be applied in crop planting.

[0024] The beneficial effects of the present invention are:

[0025] (1) The preparation method of the floating relay catalyst for producing agricultural nitrogen fertilizer designed by the present invention is simple, easy to operate, economical and environmentally friendly, does not produce toxic and harmful by-products, has strong versatility, uses simple and safe conditions, and has cheap and readily available raw materials, which is easy to achieve large-scale production;

[0026] (2) The floating relay catalyst designed by the present invention for producing agricultural nitrogen fertilizer not only cleverly solves the problem of N 2 The problem of insufficient supply of reactants and the system based on TiO 2 Total nitrogen fixation technology 2 The photothermal energy generated by the CC carrier of the photothermal material is used to activate the N 2 Carry out co-activation to effectively improve the utilization efficiency of solar energy;

[0027] (3) The present invention uses the photocatalytic nitrogen fixation product produced by the floating relay catalyst to be applied to the cultivation of lettuce crops, which provides direction for the practical application of low-concentration ammonia water obtained in the research of photocatalytic ammonia synthesis, lays a foundation for further realizing its large-scale practical application and provides valuable reference. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The Bi / TiO prepared in Example 1 of the present invention 2 / XRD spectrum of CC-1 catalyst;

[0029] Figure 2 The Bi / TiO prepared in Example 1 of the present invention 2 / DRS spectrum of CC-1 catalyst;

[0030] Figure 3 This is an infrared thermal imaging image of the catalyst prepared in Example 1 of the present invention supported on a non-photothermal material Nylon66 carrier;

[0031] Figure 4 This is an infrared thermal imaging image of the catalyst prepared in Example 1 of the present invention loaded on the CC carrier of the present application.

[0032] FIG. 5( a ) shows the plant height index of lettuce in Example 3 and its comparative example.

[0033] FIG. 5( b ) shows the stem thickness index of lettuce in Example 3 and its comparative example.

[0034] FIG. 5( c ) shows the maximum leaf area index of the lettuces of Example 3 and its comparative example.

[0035] Figure 6 The relative chlorophyll SPAD content of the lettuce in Example 3 and its comparative example. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0037] Example 1

[0038] 0.2 g BiCl 3 Add to 50 mL of anhydrous ethanol and stir at room temperature for 0.5 h, then add 0.1 g of commercial TiO 2 , and transferred it to a sealed reactor. After argon was continuously introduced for 30 min, the -2 The reaction was carried out under a xenon lamp for 1.0 h. After the solution was cooled to room temperature, the precipitate was separated by a centrifuge, washed with anhydrous ethanol for 3 to 4 times and vacuum dried to obtain Bi / TiO 2Then, 0.01 g of the Bi / TiO 2 After ultrasonic dispersion in 0.2 mL Nafion / ethanol solution to form a uniform solution, it was loaded on a 2×2 cm 2 The Bi / TiO 2 / CC relay catalyst, denoted as Bi / TiO 2 / CC-1. Figure 1 The XRD patterns shown demonstrate that Bi / TiO 2 / Successful synthesis of CC-1 catalyst. Figure 2 The DRS spectra shown demonstrate that Bi / TiO 2 / CC-1 catalyst has strong light absorption in the wavelength range of 200-800nm, revealing the nature of CC carrier photothermal materials.

[0039] The obtained Bi / TiO 2 / CC-1 was used for photocatalytic nitrogen fixation reaction. The reaction conditions were as follows: the simulated sunlight light source was a xenon lamp with a power of 300W, a custom sealed quartz reactor was used, 20mL of deionized water was used as the proton source, and Bi / TiO 2 / CC-1 floats on the surface of the liquid phase. Before irradiation, nitrogen was introduced into the sealed reactor for 30 minutes to remove impurities adsorbed on the catalyst surface and exhaust the air in the reactor. After the light was turned on for 1 hour, the solution was cooled to room temperature, and 5 mL of solution was extracted from the reactor respectively. The concentrations of ammonia and nitrate products were quantitatively analyzed using an ultraviolet spectrophotometer. The performance test results are shown in Table 1. The ammonia and nitrate products detected simultaneously in the nitrogen fixation product solution show that Bi / TiO 2 / CC-1 catalyst system has full nitrogen fixation performance.

[0040] Comparative Example 1-1

[0041] Prepare Bi / TiO according to Example 1 2 The catalyst was directly subjected to a photocatalytic nitrogen fixation reaction experiment test. The reaction conditions and operation were the same as those in Example 1. The difference was that 0.01 g Bi / TiO 2 The powder was directly dispersed in 20 mL of aqueous solution, and the performance test results are shown in Table 1. 2 The nitrogen fixation activity in the powder system is lower than that of Bi / TiO 2 / CC-1, indicating that the design of the floating system can effectively solve the problem of N 2 The problem of insufficient supply of reactants in traditional powders provides sufficient N for nitrogen fixation reaction 2 source, thereby promoting the improvement of nitrogen fixation performance.

[0042] Comparative Example 1-2

[0043] Prepare Bi / TiO according to Example 1 2 The obtained photocatalyst was loaded on a 2×2 cm 2 The non-photothermal material Nylon66 was used as the carrier, and then dried under infrared light to obtain Bi / TiO 2 / Nylon66 catalyst system, denoted as Bi / TiO 2 / Nylon66. Figure 3 The infrared thermal imaging image shows that the non-photothermal carrier Bi / TiO 2 The photothermal temperature of the / Nylon66 system is only 55.4°C, which is lower than that of the photothermal carrier Bi / TiO 2 / CC-1 system( Figure 4 ) with a photothermal temperature of 64.9°C. The photocatalytic nitrogen fixation reaction was tested, and the reaction conditions and operation were the same as in Example 1. The performance test results are shown in Table 1. The non-photothermal carrier Bi / TiO 2 / Nylon66 system shows lower performance than the photothermal carrier Bi / TiO 2 / CC-1 has a strong nitrogen fixation activity, indicating that the photothermal energy generated by the photothermal material CC carrier has a significant promoting effect on the enhancement of nitrogen fixation activity.

[0044] Comparative Examples 1-3

[0045] 0.01 g TiO 2 Coated on 2×2cm 2 The CC support of size is denoted as TiO 2 / CC, and a photocatalytic nitrogen fixation reaction experiment was conducted on it. The reaction conditions and operation were the same as those in the above-mentioned Example 1, except that the system did not contain Bi components. The performance test results are shown in Table 1. It can be seen from the results that TiO 2 / CC system showed higher performance than Bi / TiO 2 / CC-1 has a lower photocatalytic activity for nitrate synthesis than Bi / TiO 2 / CC-1 has a significant photocatalytic ammonia synthesis activity, indicating that the Bi component plays an important role in promoting the photocatalytic ammonia synthesis.

[0046] Table 1 Photocatalytic nitrogen fixation performance of catalysts prepared in Example 1 and its comparative example / mmol L -1 g -1 h -1

[0047] product <![CDATA[Bi / TiO 2 ]]> <![CDATA[Bi / TiO 2 / CC-1]]> <![CDATA[Bi / TiO 2 / Nylon66]]> <![CDATA[TiO 2 / CC]]> <![CDATA[NH 4 + ]]> 1.41 4.40 3.46 1.37 <![CDATA[NO 3 - ]]> 0.50 0.67 0.54 1.99

[0048] Example 2

[0049] 0.4 g BiCl 3 Add to 50 mL of anhydrous ethanol and stir at room temperature for 0.5 h, then add 0.1 g of commercial TiO 2 , and transferred it to a sealed reactor. After argon was continuously introduced for 30 min, the -2 The reaction was carried out under a xenon lamp for 1.0 h. After the solution was cooled to room temperature, the precipitate was separated by a centrifuge, washed with anhydrous ethanol for 3 to 4 times and vacuum dried to obtain Bi / TiO 2 Then, 0.01 g of the Bi / TiO 2 After ultrasonic dispersion in 0.2 mL Nafion / ethanol solution to form a uniform solution, it was loaded on a 2×2 cm 2 The Bi / TiO 2 / CC relay catalyst, denoted as Bi / TiO 2 / CC-2.

[0050] The obtained Bi / TiO 2 / CC-2 was used for photocatalytic nitrogen fixation reaction. The reaction conditions were as follows: the simulated sunlight light source was a xenon lamp with a power of 300W, a custom sealed quartz reactor was used, 20mL of deionized water was used as the proton source, and Bi / TiO 2 / CC-2 floats on the surface of the liquid phase. Before irradiation, nitrogen was introduced into the sealed reactor for 30 minutes to remove impurities adsorbed on the catalyst surface and to exhaust the air in the reactor. After the light was turned on for 1 hour, the solution was cooled to room temperature, and 5 mL of solution was extracted from the reactor respectively, and the concentrations of ammonia and nitrate products were quantitatively analyzed using an ultraviolet spectrophotometer.

[0051] Example 3

[0052] 0.2 g BiCl 3 Add to 50 mL of anhydrous ethanol and stir at room temperature for 0.5 h, then add 0.1 g of commercial TiO 2 , and transferred it to a sealed reactor. After argon was continuously introduced for 30 min, the -2 The reaction was carried out under a xenon lamp for 1.0 h. After the solution was cooled to room temperature, the precipitate was separated by a centrifuge, washed with anhydrous ethanol for 3 to 4 times and vacuum dried to obtain Bi / TiO 2 Then, 0.04 g of the Bi / TiO 2 After ultrasonic dispersion in 0.8 mL Nafion / ethanol solution to form a uniform solution, it was loaded on a 4×4 cm2 The Bi / TiO 2 / CC relay catalyst, denoted as Bi / TiO 2 / CC-3.

[0053] The obtained Bi / TiO 2 The photocatalytic nitrogen fixation product solution of / CC-3 is used in crop planting. The reaction conditions are as follows: the simulated sunlight light source is a xenon lamp with a power of 300W, a custom sealed quartz reactor is used, 20mL of deionized water is used as the proton source, and Bi / TiO 2 / CC-3 floats on the surface of the liquid phase. Before irradiation, nitrogen was introduced into the sealed reactor for 30 minutes to remove impurities adsorbed on the catalyst surface and exhaust the air in the reactor. After the light was turned on for 2 hours, the solution was cooled to room temperature to obtain Bi / TiO 2 / CC-3 photocatalytic nitrogen fixation product solution. After the lettuce was planted, 20 mL of nitrogen fixation product solution was added to the lettuce crop every 3 days, and the growth and physiological indicators of the lettuce were measured. During the harvest period, the yield and quality indicators of the lettuce were measured.

[0054] The present invention provides the above-mentioned floating Bi / TiO 2 The performance evaluation of Bi / TiO / CC catalyst for photocatalytic synthesis of ammonia and nitrate and its application in crop cultivation. Specifically, the performance evaluation method is as follows: a 300W xenon lamp is used as the simulated sunlight light source, a customized sealed quartz reactor is used, 20-100mL deionized water is used as the proton source, and 2 / CC catalyst system floats on the surface of liquid water. Before irradiation, nitrogen is introduced into the sealed reactor for 30 to 60 minutes to remove impurities adsorbed on the catalyst surface and exhaust the air in the reactor. After 0.5 to 5 hours of light irradiation, 5 mL of solution is taken from the reactor respectively to quantitatively analyze the concentrations of ammonia and nitrate products. The absorbance is measured by UV-visible spectrophotometer, wherein the concentration of ammonia product is calculated based on the characteristic absorption peak at 420 nm of Nessler's reagent method; under the condition of adding 0.1 mL 1M HCl and 0.01 mL 0.8 wt% aminosulfonic acid solution, the absorbance measured at 220 nm and 275 nm (A=A 220nm -2A 275nm ) to calculate the nitrate product concentration and thus determine the Bi / TiO 2 Photocatalytic nitrogen fixation performance and reaction mechanism of the / CC catalyst system. The application conditions in crop planting are: floating Bi / TiO 2The product solution produced by the photocatalytic nitrogen fixation reaction of the / CC catalyst system is directly applied to the planting of lettuce crops. After planting, 20 to 50 mL of nitrogen fixation product solution is added to each lettuce crop every 1 to 3 days, and the growth physiological related indicators of lettuce are measured, including:

[0055] (1) Growth indicators: plant height, stem diameter and maximum leaf area, such as Figure 5(a)-Figure 5(c) Root system parameters (total root length, total root surface area, total root volume and average root diameter, etc.) are shown in Table (2).

[0056] Table 2 Example 3 and its comparative example lettuce root growth index

[0057] Irrigation solution Total root length (cm) <![CDATA[Total root volume (cm 3 )]]> Average root diameter (mm) <![CDATA[Total root surface area (cm 2 )]]> <![CDATA[Bi / TiO 2 / CC-3 reaction solution]]> 574.61 6.77 0.81 181.08 water 547.22 6.39 0.73 157.11

[0058] (2) Physiological indicators: relative chlorophyll SPAD content such as Figure 6 The photosynthetic parameters (net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration and transpiration rate, etc.) are shown in Table 3.

[0059] Table 3 Photosynthetic index of lettuce in Example 3 and its comparative example

[0060]

[0061] (3) The yield (fresh weight and dry weight) and quality indicators (vitamin C, soluble sugar and soluble protein content, etc.) at the harvest period are shown in Table 4.

[0062] Table 4 Example 3 and its comparative example lettuce yield and quality index

[0063]

[0064] The above diagram shows that the use of Bi / TiO 2 The nitrogen-fixing product solution generated by the / CC-3 catalyst has better lettuce growth, faster physiological effects, higher yield and better quality than the lettuce irrigated with pure water solution, which proves the promoting effect of the nitrogen-fixing reaction solution on the growth of lettuce.

[0065] Comparative Example 3-1

[0066] According to the method in Example 3, after the lettuce was planted, 20 mL of pure water solution was added to the lettuce crop every 3 days, and the growth and physiological indicators of the lettuce were measured. The yield and quality indicators of the lettuce were measured during the harvest period. From the comparison of the four indicators of lettuce growth, physiology, yield and quality, the effect of pure water irrigation on lettuce was worse than that of Bi / TiO 2 / Nitrogen fixation product solution generated by CC-3 catalyst.

Claims

1. A method for preparing a floating relay catalyst for producing agricultural nitrogen fertilizer, characterized in that: Using titanium dioxide, bismuth trichloride and anhydrous ethanol as raw materials and ethanol as solvent, Bi / TiO2 material is prepared by a one-step photoreduction method, then ultrasonically dispersed in a perfluorosulfonic acid polymer solution or an ethanol solution, and loaded on a CC carrier by a coating method to obtain a floating relay catalyst for producing agricultural nitrogen fertilizer; the specific operation steps are as follows: Step 1: Weigh bismuth trichloride, place it in anhydrous ethanol, and stir it at room temperature for 0.5 to 1.0 h until it is completely dissolved to obtain solution A; The ratio of bismuth trichloride to anhydrous ethanol is 0.2-0.8 g: 50-100 mL; Step 2: Weigh TiO2 and place it in solution A. Stir and mix for 0.5-1.0 h, then transfer it to a sealed quartz reactor. Continue to introduce argon for 30-60 min, and then heat it at 50-150 mW cm -2 The light reaction was conducted under a xenon lamp with a light intensity of 0.5 to 1.5 h; The mass ratio of the bismuth trichloride in step 1 to the TiO2 in step 2 is 2-8:1-2; Step 3: After the reaction is completed, the solution is cooled to room temperature, the precipitate is separated by centrifuge, washed with anhydrous ethanol 3 to 4 times, and heated at 50 to 70 o C and dried under vacuum conditions to obtain the Bi / TiO2 catalyst; Step 4: Weigh the Bi / TiO2 catalyst and place it in a 0.5-1.0% perfluorosulfonic acid polymer solution / ethanol solution. After ultrasonic mixing for 0.5-2h, the mixture is loaded on a 2×2-100×100 cm 2 On carbon cloth of different sizes, and finally dried under infrared light, floating Bi / TiO2 / CC relay catalyst; The ratio of the Bi / TiO2 catalyst to the perfluorosulfonic acid type polymer solution is 0.01-5 g: 0.2-100 mL.

2. The method for preparing a floating relay catalyst for producing agricultural nitrogen fertilizer according to claim 1, characterized in that: The floating Bi / TiO2 / CC relay catalyst comprises a CC carrier and a Bi / TiO2 photocatalyst, wherein the Bi / TiO2 photocatalyst is distributed on the surface of the CC carrier; the loading amount of the Bi / TiO2 on the CC carrier is 0.01 to 5 g / cm 2 .

3. The method for preparing a floating relay catalyst for producing agricultural nitrogen fertilizer according to claim 1, characterized in that: The application of the prepared floating Bi / TiO2 / CC catalyst in crop planting is as follows: The nitrogen fixation product obtained by the photocatalytic nitrogen fixation reaction of the floating Bi / TiO2 / CC catalyst is directly irrigated during the crop growth period; the photocatalytic nitrogen fixation reaction conditions are: A 300 W xenon lamp was used as the simulated sunlight light source, a custom sealed quartz reactor was used, and 20-100 mL of deionized water was used as the proton source. Before illumination, nitrogen was introduced into the sealed reactor for 30-60 min. After the light was turned on for 0.5-5 h, an aqueous solution of nitrogen-fixing products was obtained. The aqueous solutions of nitrogen-fixing products were taken from the reactor, and the concentrations of ammonia and nitrate were quantitatively analyzed using a UV-visible spectrophotometer according to the colorimetric method. The application conditions of the nitrogen-fixing product aqueous solution in crop planting are as follows: the nitrogen-fixing product aqueous solution obtained by photocatalytic nitrogen fixation reaction in the floating Bi / TiO2 / CC relay catalyst is directly applied to lettuce crop planting; 20 to 50 mL of the nitrogen-fixing product aqueous solution is added to each lettuce crop every 1 to 3 days after planting, and the growth physiology and yield quality-related indicators of lettuce are measured.

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