CN113479896B - Methods and applications of preparing calcium copper silicate materials using attapulgite and biomass - Google Patents

Abstract

The application belongs to the technical field of novel material preparation and photocatalytic ammonia synthesis, and in particular relates to a method for preparing a calcium copper silicate material by utilizing attapulgite and biomass and application thereof, wherein attapulgite powder and ammonium sulfate are mixed and calcined, the obtained calcined product is uniformly dispersed into hydrochloric acid solution with a certain concentration, solid precipitate is washed, and SiO is obtained by drying ₂ And (3) powder. SiO produced ₂ Mixing and calcining the powder, the biomass containing calcium salt and basic copper carbonate to obtain a calcium copper silicate material, and applying the calcium copper silicate material to photocatalytic nitrogen fixation synthesis of ammonia. The method is characterized in that mineral attapulgite rich in nature is skillfully utilized as a raw material, the structure of the mineral attapulgite is recombined, and the calcium copper silicate catalyst with good nitrogen fixation effect is prepared by combining the mineral attapulgite with the rest of cheap biomass materials.

Description

Methods and applications of preparing calcium copper silicate materials using attapulgite and biomass

Technical field

The invention belongs to the technical field of new material preparation and photocatalytic ammonia synthesis, and specifically relates to a method for preparing calcium copper silicate materials by using attapulgite and biomass and its application.

Background technique

The Haber–Bosch method using iron-based catalysts has been widely used in industrial synthesis of ammonia. However, the reaction needs to be carried out under high temperature and high pressure, and consumes huge amounts of energy. In today's increasingly shortage of energy, it is urgent to find a new method for synthesizing ammonia. . The photocatalytic ammonia synthesis reaction has received widespread attention in recent years. Its principle is to use sunlight to convert nitrogen into ammonia under the action of a catalyst. However, at present, photocatalysts mostly use methods such as precious metal deposition or ion doping to improve their nitrogen fixation effect, which is costly. In addition, some catalysts, such as TiO ₂ , have low light utilization efficiency due to their high bandwidth, causing their photocatalytic performance to be seriously affected.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned problems in the prior art and provide a preparation and application of a photocatalytic ammonia synthesis catalyst that is low in price, has readily available raw materials, and has high photogenerated electron hole separation efficiency. Specifically, it utilizes attapulgite and biomass. Methods for preparing calcium copper silicate materials and their applications. Its preparation method is simple, its synthesis conditions are mild and it does not require complex and expensive equipment, which is conducive to large-scale promotion.

In order to achieve the purpose of the present invention, the technical solutions adopted are:

A method for preparing calcium copper silicate material using attapulgite and biomass, including the following steps:

(1) Mix attapulgite powder and ammonium salt at a mass ratio of 1:1 to 1:5 and place them in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 400 to 400°C at a speed of 1 to 8°C/min. 700°C (SiO ₂ obtained beyond this range has more impurities such as MgO, CaO or Al ₂ O ₃ , etc., and it is preferably heated to 500°C at 2°C/min), then naturally cooled to room temperature, and the obtained calcined product is dispersed into Put it into the acid solution and stir it with hydrothermally for 1 to 5 hours, then separate the solid (preferably, the concentration of hydrochloric acid is 2mol/L, the solid-liquid ratio of the calcined product and hydrochloric acid is 1:20, and the temperature of hydrothermal stirring is 80°C), and washed , dry to obtain white SiO ₂ powder.

(2) Combine basic copper carbonate and calcium salt-containing biomass (as a preference, the calcium salt-containing biomass is eggshell powder and/or shell powder, answer: the selected biomass mainly contains calcium elements) and the steps ( 1) The prepared SiO ₂ powder is mixed with a molar ratio of 0.5~1:0.5~1:0.5~5 and then calcined at 800-1000°C for 1~5h (no calcium copper silicate can be obtained below 1h material, the calcium copper silicate becomes agglomerated and no longer forms a two-dimensional lamella over 5 hours, preferably 2 hours), and then is naturally cooled to room temperature, ground and dried to obtain the calcium copper silicate material.

Further, in step (1), the obtained calcined product is dispersed into a hydrochloric acid solution and stirred hydrothermally for 1 to 5 hours, where the hydrothermal stirring method is mechanical stirring or magnetic stirring.

Further, the ammonium salt described in step (1) is ammonium sulfate, ammonium nitrate or basic ammonium carbonate.

Further, the acid solution in step (1) is hydrochloric acid, sulfuric acid or nitric acid solution.

Application of the calcium copper silicate material prepared by the above method in photocatalytic synthesis of ammonia.

The specific application method is as follows: the calcium copper silicate material is dispersed in deionized water, and then added to the photocatalytic reaction device, _N2 is introduced and catalyzed by light to produce ammonia.

In the present invention, attapulgite, as a natural mineral clay material, has abundant reserves in my country because of its good dispersibility, large specific surface area and unique one-dimensional nanorod-like structure. Since attapulgite is rich in SiO ₂ , SiO ₂ raw materials can be produced by completely destroying its octahedral structure and ensuring that its rod-like structure remains unchanged. SiO ₄ tetrahedrons in transition metal cation silicates are prone to distortion and polarization. Thereby enhancing the migration of photogenerated carriers. Furthermore, silicate-based photocatalysts hold great promise due to their low cost and abundant reserves. In addition, the main component of calcium-containing biomass materials such as egg shell powder, shell powder, etc. is calcium carbonate. This application introduces calcium ions and copper ions into the catalytic material through calcination, which has better adsorption of nitrogen during the nitrogen fixation process. Activation determines the faster reaction speed, and the introduced calcium and copper metal ions can create defective sites in the material, thereby achieving adsorption and activation of nitrogen. In addition, the introduction of calcium ions can also cause lattice distortion in the original silicate structure and generate oxygen vacancies. Oxygen vacancies and defect sites can cooperatively adsorb and activate nitrogen molecules, thereby improving the efficiency of photocatalytic nitrogen fixation.

Therefore, compared with the existing technology, the advantage of the present invention is that it selects natural attapulgite, malachite and other minerals and calcium-containing biomass that are abundant in nature as raw materials, introduces metal elements Ca and Cu, and synthesizes them through high-temperature solid-phase reaction. The structure is stable, has a two-dimensional lamellar structure, high photogenerated electron hole separation efficiency, and is a new calcium silicate copper photocatalyst with good photocatalytic ammonia synthesis effect; at the same time, this method has rich sources of raw materials, low cost, environmental friendliness, simple preparation process, and has Conducive to large-scale promotion.

Description of the drawings

Figure 1 is the XRD pattern and corresponding PDF card of 800-CaCuSi ₄ O ₁₀ prepared in Example 1;

Figure 2 is a TEM image of the 100nm scale range of the 800-CaCuSi ₄ O ₁₀ sample prepared in Example 1.

Detailed ways

The present invention is not limited to the following specific embodiments. Based on the disclosure of the present invention, those of ordinary skill in the art can adopt a variety of other specific embodiments to implement the present invention, or simply change or adopt the design structure and ideas of the present invention. Any modifications fall within the protection scope of the present invention. It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

The present invention will be further described in detail below in conjunction with the examples:

Example 1

(1) Mix 5g of attapulgite powder and ammonium sulfate at a mass ratio of 1:1 and place it in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 500°C at a rate of 2°C/min, and then cool it naturally to At room temperature, the obtained calcined product was dispersed into a 2 mol/L hydrochloric acid solution at a solid-to-liquid ratio of 1:20. After hydrothermal stirring at 80°C for 6 hours, the solid was separated, washed, and dried to obtain white SiO ₂ powder.

(2) Mix 1.11g Cu ₂ (OH) ₂ CO ₃ and 1.0g eggshell powder with 0.6g of the prepared SiO ₂ powder, place it in a crucible, and transfer it to a muffle furnace at 800°C. Calcined for 2 hours, then naturally cooled to room temperature, ground and dried to obtain calcium copper silicate material, recorded as 800-CaCuSi ₄ O ₁₀ .

The 800-CaCuSi ₄ O ₁₀ material prepared in this example was subjected to X-ray powder diffraction to analyze its phase, and its morphology and structure were observed under a transmission electron microscope.

The XRD pattern is shown in Figure 1. By comparing the PDF card of CaCuSi ₄ O ₁₀ , we can know that the unique diffraction peaks of CaCuSi ₄ O ₁₀ appear at 11.6°, 23.2°, 26.3°, 39.6°, etc., and there are no impurities. peak, indicating that the 800-CaCuSi ₄ O ₁₀ produced by this method is relatively pure. At the same time, combined with the TEM photo Figure 2, it can be proved that the structure of 800-CaCuSi ₄ O ₁₀ is a multi-layer stack of two-dimensional sheets.

The present invention also provides an application method of the above-mentioned photocatalyst for photocatalytically synthesizing ammonia.

The application method is: weigh 0.04g of the prepared calcium copper silicate material 800-CaCuSi ₄ O ₁₀ and dissolve it in 100 mL of deionized water, and then add it to the photocatalytic reaction device, and N ₂ is introduced at a flow rate of 60 mL/min. The reaction device was introduced with N ₂ for 30 minutes and then irradiated with a 300W xenon lamp as a simulated light source. 10 mL samples were collected every 30 minutes, Nessler's reagent was added, the supernatant was extracted after full reaction, and the absorbance was tested at a wavelength of 420 nm with a UV spectrometer.

It was measured by the above method that the NH ₄ ⁺ generation rate of 800-CaCuSi ₄ O ₁₀ reached 58.47 μmol·g ^-1 ·h ^-1 after 120 minutes.

It was measured by the above method that when the calcination temperature in step (2) is 1000°C, the NH ₄ ⁺ generation rate of CaCuSi ₄ O ₁₀ obtained after 120 minutes reaches 60.32 μmol·g ^-1 ·h ^-1 .

Example 2

(1) Mix 5g of attapulgite powder and ammonium sulfate at a mass ratio of 1:2 and place it in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 500°C at a rate of 2°C/min, and then cool it naturally to At room temperature, the obtained calcined product was dispersed into a 2 mol/L hydrochloric acid solution at a solid-to-liquid ratio of 1:20. After hydrothermal stirring at 80°C for 6 hours, the solid was separated, washed, and dried to obtain white SiO ₂ powder.

(2) Mix 1.11g Cu ₂ (OH) ₂ CO ₃ and 1.0g eggshell powder with 1.2g of the prepared SiO ₂ powder, place it in a crucible, and transfer it to a muffle furnace at 850°C. Calcined for 2 hours, then naturally cooled to room temperature, ground and dried to obtain 850-CaCuSi ₄ O ₁₀ .

The subsequent detection was as in Example 1. After 120 minutes, the NH ₄ ⁺ generation rate reached 86.88 μmol·g ^-1 ·h ^-1 .

Example 3

(1) Mix 5g of attapulgite powder and ammonium sulfate at a mass ratio of 1:3 and place it in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 500°C at a speed of 2°C/min, and then cool it naturally to At room temperature, the obtained calcined product was dispersed into a 2 mol/L hydrochloric acid solution at a solid-to-liquid ratio of 1:20. After hydrothermal stirring at 80°C for 6 hours, the solid was separated, washed, and dried to obtain white SiO ₂ powder.

(2) Mix 1.11g Cu ₂ (OH) ₂ CO ₃ and 1.0g eggshell powder with 1.8g of the prepared SiO ₂ powder, place it in a crucible, and transfer it to a muffle furnace at 900°C. Calcined for 2 hours, then naturally cooled to room temperature, ground and dried to obtain 900-CaCuSi ₄ O ₁₀ .

The subsequent detection was as in Example 1. After 120 minutes, the NH ₄ ⁺ generation rate reached 124.68 μmol·g ^-1 ·h ^-1

Example 4

(1) Mix 5g of attapulgite powder and ammonium sulfate at a mass ratio of 1:4 and place it in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 500°C at a rate of 2°C/min, and then cool it naturally to At room temperature, the obtained calcined product was dispersed into a 2 mol/L hydrochloric acid solution at a solid-to-liquid ratio of 1:20. After hydrothermal stirring at 80°C for 6 hours, the solid was separated, washed, and dried to obtain white SiO ₂ powder.

(2) Mix 1.11g Cu ₂ (OH) ₂ CO ₃ and 1.0g eggshell powder with 2.4g of the prepared SiO ₂ powder, place it in a crucible, and transfer it to a muffle furnace at 950°C. Calcined for 2 hours, then naturally cooled to room temperature, ground and dried to obtain 950-CaCuSi ₄ O ₁₀ .

The subsequent detection was as in Example 1. After 120 minutes, the NH ₄ ⁺ generation rate reached 107.96 μmol·g ^-1 ·h ^-1 .

Example 5

(1) Mix 5g of attapulgite powder and ammonium sulfate at a mass ratio of 1:5 and place it in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 500°C at a rate of 2°C/min, and then cool it naturally to At room temperature, the obtained calcined product was dispersed into a 2 mol/L hydrochloric acid solution at a solid-to-liquid ratio of 1:20. After hydrothermal stirring at 80°C for 6 hours, the solid was separated, washed, and dried to obtain white SiO ₂ powder.

(2) Mix 1.11g Cu ₂ (OH) ₂ CO ₃ and 1.0g eggshell powder with 3.0g of the prepared SiO ₂ powder, place it in a crucible, and transfer it to a muffle furnace at 1000°C. Calcined for 2 hours, then naturally cooled to room temperature, ground and dried to obtain 1000-CaCuSi ₄ O ₁₀ .

The subsequent detection was as in Example 1. After 120 minutes, the NH ₄ ⁺ generation rate reached 78.45 μmol·g ^-1 ·h ^-1 .

Comparative Example 1

(1) Mix 5g of attapulgite powder and ammonium sulfate at a mass ratio of 1:1 and place it in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 500°C at a rate of 2°C/min, and then cool it naturally to At room temperature, the obtained calcined product was dispersed into a 2 mol/L hydrochloric acid solution at a solid-to-liquid ratio of 1:20. After hydrothermal stirring at 80°C for 6 hours, the solid was separated, washed, and dried to obtain white SiO ₂ powder.

(2) Take 2.4g of the prepared SiO ₂ powder and mix it with 1.11g of Cu ₂ (OH) ₂ CO ₃ , place it in a crucible, and transfer it to a muffle furnace at 800°C. Calcined under the conditions for 2 hours, then naturally cooled to room temperature, ground and dried to obtain CuSiO ₃ .

Subsequent testing was as in Example 1. After 120 minutes, the NH ₄ ⁺ generation rate only reached 27.36 μmol·g ^-1 ·h ^-1 , so there was no photoresponse in the near-infrared region, resulting in a weak photocatalytic nitrogen fixation effect of CuSiO ₃ under the same circumstances. in CaCuSi ₄ O ₁₀ .

Comparative Example 2

(1) Mix 5g of attapulgite powder and ammonium sulfate at a mass ratio of 1:1 and place it in a ceramic crucible. Place the crucible into a muffle furnace and raise it to 500°C at a rate of 2°C/min, and then cool it naturally to At room temperature, the obtained calcined product was dispersed into a 2 mol/L hydrochloric acid solution at a solid-to-liquid ratio of 1:20. After hydrothermal stirring at 80°C for 6 hours, the solid was separated, washed, and dried to obtain white SiO ₂ powder.

(2) Mix 2.4g of the prepared SiO ₂ powder with 1.0g of eggshell powder, place it in a crucible, transfer it to a muffle furnace, and calcine at 800°C for 2 hours. Cool to room temperature naturally, grind and dry to obtain CaSiO ₃ .

The subsequent detection was as in Example 1. After 120 minutes, the NH ₄ ⁺ generation rate only reached 33.42 μmol·g ^-1 ·h ^-1 .

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can, within the technical scope disclosed in the present invention, implement the technical solutions of the present invention. Any equivalent substitutions or changes in the concepts thereof shall be included in the protection scope of the present invention.

Claims (9)

1. The application of the calcium copper silicate material prepared by using attapulgite and biomass is characterized in that:

the preparation of the calcium silicate copper material by using the attapulgite and biomass comprises the following steps:

(1) Mixing attapulgite powder and ammonium salt in a mass ratio of 1:1-1:5, placing the mixture into a ceramic crucible, placing the crucible into a muffle furnace, heating to 400-700 ℃ at a speed of 1-8 ℃/min, naturally cooling to room temperature, dispersing the obtained calcined product into an acid solution, hydrothermally stirring for 1-5 h, separating out solids, washing, and drying to obtain white SiO ₂ A powder;

(2) Mixing basic cupric carbonate and biomass containing calcium salt with SiO prepared in step (1) ₂ The powder is prepared from the following components in percentage by mole (0.5-1): 0.5-1: mixing the materials according to a feeding ratio of 0.5-5, calcining for 1-5 h at 800-1000 ℃, naturally cooling to room temperature, grinding and drying to obtain the calcium copper silicate material;

the application refers to the use for photocatalytic synthesis of ammonia.

2. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: the temperature rising speed in the step (1) is 2 ℃/min, and the temperature rises to 500 ℃.

3. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: the acid solution in the step (1) is hydrochloric acid solution, the concentration of the hydrochloric acid solution is 2mol/L, the solid-to-liquid ratio of the calcined product to the hydrochloric acid is 1:20, and the temperature of hydrothermal stirring is 80 ℃.

4. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: the biomass containing calcium salt in the step (2) is eggshell powder and/or shell powder.

5. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: the calcination time described in step (2) was 2 h.

6. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: the method comprises the following steps: dispersing the calcium silicate copper material in deionized water, then adding the deionized water into a photocatalytic reaction device, and introducing N ₂ And carrying out photocatalysis by illumination to obtain ammonia.

7. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: and (3) dispersing the obtained calcined product in the step (1) into hydrochloric acid solution and carrying out hydrothermal stirring for 1-5 h, wherein the hydrothermal stirring method is mechanical stirring or magnetic stirring.

8. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: the ammonium salt in the step (1) is ammonium sulfate, ammonium nitrate or basic ammonium carbonate.

9. The use of the calcium copper silicate material prepared from attapulgite and biomass according to claim 1, wherein: the acid solution in the step (1) is hydrochloric acid, sulfuric acid or nitric acid solution.