CN115779914B - Copper bismuthate/calcium bismuthate composite material, preparation method and application thereof in photocatalytic plastic conversion into hydrocarbon fuels - Google Patents

Abstract

The invention relates to a preparation method of a copper bismuthate/calcium bismuthate composite material, which comprises the following steps: dissolving bismuth nitrate pentahydrate and disodium ethylenediamine tetraacetate in an acetic acid solution, then adding absolute ethyl alcohol, and stirring to obtain a clear solution; adding copper nitrate trihydrate and calcium nitrate tetrahydrate, stirring for 0.5-2h, and then adding sodium hydroxide solution to obtain a copper bismuthate/calcium bismuthate composite material precursor solution; then placing the mixture in an oven for heat preservation, naturally cooling, centrifuging, washing and drying to obtain the finished product. The composite material has good photocatalytic activity on various plastic raw materials, and has wide application prospects in the fields of photocatalytic CO ₂ conversion, waste plastic treatment and the like.

Description

Copper bismuthate/calcium bismuthate composite material, preparation method and application thereof in photocatalytic plastic conversion into carbon hydrogen fuel

Technical Field

The present invention belongs to the technical fields of composite material preparation and photocatalytic plastic resource utilization, and specifically relates to a copper bismuthate/calcium bismuthate composite material, a preparation method and application thereof in photocatalytic plastic conversion into hydrocarbon fuels.

Background technique

With the rapid development of society and industry, environmental pollution and fossil fuel depletion have become one of the problems that endanger human survival and development. Photocatalytic technology has gradually attracted widespread attention due to its high efficiency, low cost, and green environmental protection. At the same time, plastic materials have become one of the important materials in social construction and development due to their stable chemical structure and good physical properties. However, the large-scale use of plastics and their difficulty in degradation have gradually formed serious white pollution. However, carbon dioxide and plastics are both important carbon resources in nature. Effectively accelerating the carbon cycle can not only solve environmental problems, but also effectively alleviate energy shortages.

The key to photocatalytic technology lies in the development of efficient and stable photocatalysts. Although existing commercial photocatalytic materials such as P25 (TiO ₂ ) show good photocatalytic performance, they still have defects such as too narrow light response range of the material and low solar energy utilization rate. Therefore, it is still necessary to further study and develop catalysts used in carbon conversion.

Summary of the invention

The purpose of the present invention is to overcome the defects of the prior art and provide a copper bismuthate/calcium bismuthate composite material, which exhibits good photocatalytic activity for a variety of plastic raw materials and has broad application prospects in the fields of photocatalytic _CO2 conversion and waste plastic treatment.

The present invention also provides a preparation method of the copper bismuthate/calcium bismuthate composite material and its application in photocatalytic plastic conversion into hydrocarbon fuels.

To achieve the above object, the present invention adopts the following technical solution:

A method for preparing a copper bismuthate/calcium bismuthate composite material comprises the following steps:

1) Dissolve bismuth nitrate pentahydrate and disodium ethylenediaminetetraacetate (EDTA-2Na) in acetic acid solution, then add anhydrous ethanol and stir to obtain a clear solution;

2) adding copper nitrate trihydrate and calcium nitrate tetrahydrate to the clear solution obtained in step 1), stirring for 0.5-2h, and then adding sodium hydroxide solution to obtain a copper bismuthate/calcium bismuthate composite material precursor solution;

3) The copper bismuthate/calcium bismuthate composite material precursor solution obtained in step 2) is placed in an oven for heat preservation, cooled naturally, centrifuged, washed, and dried to obtain a composite material.

Specifically, in step 1), 1.94-14.55 g of bismuth nitrate pentahydrate and 0.5-6.0 g of disodium ethylenediaminetetraacetate can be dissolved in an acetic acid solution.

In the above preparation method, specifically, in step 2), 0.48-3.62 g of copper nitrate trihydrate and 0.16-1.18 g of calcium nitrate tetrahydrate can be added.

In the above preparation method, further, in step 2), 40 mL to 80 mL of a sodium hydroxide solution with a concentration of 9 to 11 mol/L can be added.

In the above preparation method, further, in step 3), the copper bismuthate/calcium bismuthate composite material precursor solution can be placed in an oven at 180° C.-230° C. for 6-36 hours.

Furthermore, the present invention provides a preferred method for preparing the copper bismuthate/calcium bismuthate composite material, which is specifically as follows:

1) Add 1.94-14.55 g of bismuth nitrate pentahydrate and 0.5-6.0 g of disodium ethylenediaminetetraacetate to 15-25 mL of acetic acid solution (3-7 mol/L), sonicate for 20-30 minutes to dissolve, then add 5-10 mL of anhydrous ethanol and stir for 0.5-3 hours to obtain a clear solution;

2) adding 0.48-3.62 g of copper nitrate trihydrate and 0.16-1.18 g of calcium nitrate tetrahydrate to the clear solution obtained in step 1), stirring for 0.5-2 hours, and then adding 40 mL-80 mL of sodium hydroxide solution (10 mol/L) to obtain a copper bismuthate/calcium bismuthate composite material precursor solution;

3) Pour the above precursor solution into a 200mL reactor, directly put it into an oven at 180℃-230℃ for 6-36h, cool it naturally to room temperature, and obtain red powder by centrifugation. Wash it with distilled water and anhydrous ethanol respectively, and place the powder in a vacuum oven at a vacuum degree of more than 0.8MPa and dry it at 50-70℃ to obtain copper bismuthate/calcium bismuthate powder.

The invention provides a copper bismuthate/calcium bismuthate composite material prepared by the above-mentioned preparation method.

The present invention also provides the use of the copper bismuthate/calcium bismuthate composite material in photocatalytic plastic conversion into hydrocarbon fuels. The plastic may be polyethylene (PE) and polypropylene (PP).

In the present invention, copper bismuthate and calcium bismuthate are not only green, environmentally friendly and inexpensive semiconductors, but can also effectively absorb solar energy in the visible light region; at the same time, both have excellent catalytic reduction and catalytic oxidation reaction capabilities, respectively. Secondly, carbon dioxide and household plastics are both valuable carbon resources, and the effective conversion of both into hydrocarbon fuels has good economic prospects. The present invention designs a method for preparing a copper bismuthate/calcium bismuthate composite material by one-step hydrothermal synthesis. The composite material has a stable structure, good solar energy utilization and photocatalytic carbon conversion activity, and has broad application prospects in the fields of photocatalytic _CO2 conversion and waste plastic treatment.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention adopts an alkaline solvent thermal method to prepare a copper bismuthate/calcium bismuthate composite material. The composite material exhibits good photocatalytic activity for a variety of plastic raw materials (PE or PP). At the same time, when the optimal component is PE plastic as a reactant and illuminated under visible light (λ>400 nm) for 8 hours, the photocatalytic product CO and CH ₄ yields are more than 6.5 times higher than the yield of the commercial photocatalyst P25, and the yields can reach about 5.2 μmol/g _cat /h and 28.5 μmol/g _cat /h respectively; when PP plastic is a reactant and illuminated for 10 hours, the photocatalytic product CO and CH ₄ yields reach 26.5 μmol/g _cat /h and 4.2 μmol/g _cat /h respectively. In the catalytic system with two plastics as reactants, after the sample is cycled 8 times, the yield of CH ₄ generated by visible light catalytic reduction of CO ₂ decreases by less than 13%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an XRD diagram of the copper bismuthate/calcium bismuthate composite material samples prepared in Examples 1-8 of the present invention;

FIG2 is a SEM image of copper bismuthate/calcium bismuthate composite material samples prepared in Examples 1 (a), 2 (b), 3 (c), 4 (d), 5 (e), and 6 (f) of the present invention;

FIG3 is a schematic structural diagram of a photocatalytic reactor according to the present invention;

FIG4 is a photocatalytic activity diagram of copper bismuthate/calcium bismuthate composite material samples prepared in Examples 1-8 of the present invention; in the figure, a: PE plastic is used as a reactant and is irradiated for 8 hours, and b: PP plastic is used as a reactant and is irradiated for 10 hours;

FIG5 is a diagram of the cyclic catalytic activity of the copper bismuthate/calcium bismuthate composite material sample prepared in Example 6 of the present invention; in the diagram, a: PE plastic is the reactant, and b: PP plastic is the reactant.

Detailed ways

The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

In the following examples, unless otherwise specified, the raw materials used are commercially available products that can be directly purchased or prepared according to conventional methods in the art. Room temperature refers to 25±5°C.

Example 1

A method for preparing a copper bismuthate/calcium bismuthate composite material, which specifically comprises the following steps:

1) Add 5.82 g of bismuth nitrate pentahydrate and 4.0 g of disodium ethylenediaminetetraacetate to 20 mL of acetic acid solution (5 mol/L), sonicate for 30 minutes to dissolve, then add 5 mL of anhydrous ethanol and stir for 0.5 hour to obtain a clear solution;

2) Add 1.21 g of copper nitrate trihydrate and 0.16 g of calcium nitrate tetrahydrate to the clear solution obtained in step 1), and stir for 1.5 hours to obtain a precursor solution, and then add 45 mL of sodium hydroxide aqueous solution (10 mol/L) to obtain a copper bismuthate/calcium bismuthate composite material precursor solution;

3) The copper bismuthate/calcium bismuthate composite material precursor solution was poured into a 200 mL reactor and directly placed in an oven at 200°C for 12 h. After the reaction, the mixture was naturally cooled to room temperature and centrifuged at 8000 rpm to obtain a red powder. The powder was washed with distilled water and anhydrous ethanol and centrifuged 5 times each. The powder was then placed in a vacuum oven at 60°C and dried at a vacuum degree of 0.8 MPa to obtain a copper bismuthate/calcium bismuthate composite material powder.

Embodiment 2:

A method for preparing a copper bismuthate/calcium bismuthate composite material, the difference being that in step 2), 1.09 g of copper nitrate trihydrate and 0.24 g of calcium nitrate tetrahydrate are used instead of 1.21 g of copper nitrate trihydrate and 0.15 g of calcium nitrate tetrahydrate in step 2) of Example 1, and the other steps are the same as in Example 1.

Embodiment 3:

A method for preparing a copper bismuthate/calcium bismuthate composite material, the difference being that in step 2), 0.97 g of copper nitrate trihydrate and 0.32 g of calcium nitrate tetrahydrate are used instead of 1.21 g of copper nitrate trihydrate and 0.15 g of calcium nitrate tetrahydrate in step 2) of Example 1, and the other steps are the same as in Example 1.

Embodiment 4:

A method for preparing a copper bismuthate/calcium bismuthate composite material, the difference being that in step 2), 0.85 g of copper nitrate trihydrate and 0.40 g of calcium nitrate tetrahydrate are used instead of 1.21 g of copper nitrate trihydrate and 0.15 g of calcium nitrate tetrahydrate in step 2) of Example 1, and the other steps are the same as in Example 1.

Embodiment 5:

A method for preparing a copper bismuthate/calcium bismuthate composite material, which specifically comprises the following steps:

1) Add 5.82 g of bismuth nitrate pentahydrate and 4.5 g of disodium ethylenediaminetetraacetate to 20 mL of acetic acid solution (5 mol/L), sonicate for 20 minutes to dissolve, then add 5 mL of anhydrous ethanol and stir for 1 hour to obtain a clear solution;

2) Add 1.21 g of copper nitrate trihydrate and 0.16 g of calcium nitrate tetrahydrate to the clear solution obtained in step 1), and stir for 1 hour to obtain a precursor solution, and then add 60 mL of sodium hydroxide solution (10 mol/L) to obtain a rare earth copper bismuthate/calcium bismuthate composite material precursor solution;

3) Pour the copper bismuthate/calcium bismuthate composite material precursor solution into a 200 mL reactor and directly place it in an oven at 220°C for 9 h. After the reaction, cool it naturally to room temperature and centrifuge it at 8000 rpm to obtain red powder, which is washed and centrifuged 5 times with distilled water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60°C for drying under a vacuum degree of 0.8 MPa to obtain copper bismuthate/calcium bismuthate composite material powder.

Embodiment 6:

A method for preparing a copper bismuthate/calcium bismuthate composite material, the difference being that in step 2), 1.09 g of copper nitrate trihydrate and 0.18 g of calcium nitrate tetrahydrate are used instead of 1.21 g of copper nitrate trihydrate and 0.16 g of calcium nitrate tetrahydrate in step 2) of Example 1, and the other steps are the same as in Example 1.

Embodiment 7:

A method for preparing a copper bismuthate/calcium bismuthate composite material, which specifically comprises the following steps:

1) Add 14.12 g of bismuth nitrate pentahydrate and 5.7 g of disodium ethylenediaminetetraacetate to 24 mL of acetic acid solution (5 mol/L), sonicate for 30 minutes to dissolve, then add 5 mL of anhydrous ethanol and stir for 2 hours to obtain a clear solution;

2) Add 3.58 g of copper nitrate trihydrate and 0.93 g of calcium nitrate tetrahydrate to the clear solution obtained in step 1), and stir for 2 hours to obtain a precursor solution, and then add 75 mL of sodium hydroxide aqueous solution (10 mol/L) to obtain a copper bismuthate/calcium bismuthate composite material precursor solution;

3) The copper bismuthate/calcium bismuthate composite material precursor solution was poured into a 200 mL reactor and directly placed in an oven at 180°C for 30 h. After the reaction, the mixture was naturally cooled to room temperature and centrifuged at 8000 rpm to obtain a red powder. The powder was washed with distilled water and anhydrous ethanol for 5 times and then centrifuged 5 times. The powder was then placed in a vacuum oven at 60°C and dried at a vacuum degree of 0.8 MPa to obtain a copper bismuthate/calcium bismuthate composite material powder.

Embodiment 8:

A method for preparing a copper bismuthate/calcium bismuthate composite material, which specifically comprises the following steps:

1) Add 12.61 g of bismuth nitrate pentahydrate and 5.0 g of disodium ethylenediaminetetraacetate to 25 mL of acetic acid solution (5 mol/L), sonicate for 30 minutes to dissolve, then add 5 mL of anhydrous ethanol and stir for 1 hour to obtain a clear solution;

2) Add 2.56 g of copper nitrate trihydrate and 1.18 g of calcium nitrate tetrahydrate to the clear solution obtained in step 1), and stir for 2 hours to obtain a precursor solution, and then add 70 mL of sodium hydroxide aqueous solution (10 mol/L) to obtain a copper bismuthate/calcium bismuthate composite material precursor solution;

3) The copper bismuthate/calcium bismuthate composite material precursor solution was poured into a 200 mL reactor and directly placed in an oven at 230°C for 24 h. After the reaction, the mixture was naturally cooled to room temperature and centrifuged at 8000 rpm to obtain a red powder. The powder was washed with distilled water and anhydrous ethanol and centrifuged 5 times each. The powder was then placed in a vacuum oven at 60°C under a vacuum degree of 0.8 MPa and dried to obtain a copper bismuthate/calcium bismuthate composite material powder.

Characterization of the composite materials prepared in Examples 1-8

FIG1 shows the XRD diagram of the copper bismuthate/calcium bismuthate composite material samples prepared in Examples 1-8 of the present invention. As can be seen from FIG1, the characteristic peaks of the composite material samples are composed of diffraction peaks of tetragonal copper bismuthate and trigonal calcium bismuthate standards, indicating that the present invention successfully synthesized the copper bismuthate/calcium bismuthate composite material. In addition, as the content of calcium bismuthate in the composite material samples of Examples 1-8 gradually increases, the intensity of the diffraction peaks gradually becomes stronger.

FIG2 shows the SEM images of Examples 1-6 of the present invention. As shown in FIG2, the composite materials in Examples 1-4 are composed of a mixture of rod-like structural materials and sheet-like structural materials. At the same time, as the content of calcium bismuthate increases, the sheet-like material gradually increases, from which it can be inferred that the sheet-like material is calcium bismuthate and the rod-like material is copper bismuthate. In Examples 5 and 6, due to the adjustment of the content of disodium ethylenediaminetetraacetic acid, copper bismuthate presents a prominent rod-like structure, and at the same time, the sheet-like structure material increases with the increase of calcium bismuthate content.

Combined with the previous results and analysis, it can be seen that the composite samples in Examples 1-8 of the present invention are composed of rod-shaped copper bismuthate and flake-shaped calcium bismuthate.

Photocatalytic test:

The specific operation of photocatalytic performance evaluation is as follows: 0.1 g of the composite material (m ₀ ) of Example 1-8 and 2.0 g of plastic powder (100-120 mesh, polyethylene PE or polypropylene PP) are mixed, and after grinding for 30 minutes, they are spread on a quartz sand core support with a diameter of 4.0 cm, sprayed with about 1.0 g of distilled water, and moved into a CEL-GPRT100 tripod-type photocatalytic reactor (Beijing Zhongjiao Jinyuan Technology Co., Ltd., the schematic diagram of the device is shown in FIG3 ). After the reactor is sealed, high-purity carbon dioxide or high-purity nitrogen (99.99%) is introduced into it until the surface pressure of the reactor reaches 0.5 MPa, and then the gas is released. This method is used to replace and wash the gas in the reactor, and this is repeated 5 times. High-purity carbon dioxide or high-purity nitrogen was filled to 0.3MPa, and the reactor was placed in a dark room for 30 minutes. Then, a 300 W Xe arc lamp (CEL-HXF300, Beijing CEAULIGHT Co., Ltd., China) was turned on as the light source, and the irradiated light passed through an ultraviolet filter (λ> 400nm) to obtain visible irradiated light. After a certain period of illumination (t, hours), the gas outlet of the reactor was connected to a gas chromatograph, and a 3mL quantitative loop was used for injection. High-purity nitrogen (99.99%) was used as the carrier gas. The DTX-01 gas chromatograph column was used to analyze the CO and CH ₄ product content c in the gas sample through a methane reformer flame ionization detector (FID). The CO and CH ₄ product yield v=c/m _o /t.

Cyclic experiment: After the above test, the mixed solid was ground for 10 minutes, spread on a quartz sand core support, sprayed with about 1.0 g of distilled water, moved into the reactor, sealed and purged 5 times, and the catalytic activity of the sample was evaluated according to the above method.

The photocatalytic activity of the composite material of the present invention is shown in Figure 4. As can be seen from Figure 4: after 8 hours of visible light illumination, P25, copper bismuthate, and calcium bismuthate all showed weak photocatalytic carbon conversion performance, while the photocatalytic activity of the copper bismuthate/calcium bismuthate composite material prepared in Example 1-8 was greatly improved. In a _CO2 atmosphere and in the absence of plastic, the catalytic material can achieve photocatalytic reduction of _CO2 to CO and _CH4 . The same results also appear in a nitrogen atmosphere and a catalytic system with plastic powder as the reactant. In these two catalytic systems, the catalytic performance of the composite materials of Examples 1-8 is higher than that of single-component materials copper bismuthate, calcium bismuthate and commercial P25 photocatalyst materials. In the catalytic system with _CO2 atmosphere and plastic powder as the reactant, the yield of CO and _CH4 catalyzed by the composite material of Examples 1-8 is significantly higher than the sum of the yields of CO and _CH4 in the previous two catalytic systems. Therefore, the copper bismuthate/calcium bismuthate composite material of the present invention has excellent photocatalytic CO ₂ and plastic conversion performance. Among them, the composite material prepared in Example 6 can reach 5.2 and 28.5 μmol/g _cat /h on the surface of polyethylene PE plastic after 8 hours _of illumination, which is more than 6.5 times the catalytic activity of the commercial P25 photocatalyst (CO 0.8 and CH ₄ 0.3 μmol/g _cat /h). Similar results also appear in the catalytic system with polypropylene PP plastic as the reaction substrate. Among them, the composite material prepared in Example 6 can reach 26.5 and 4.2 μmol/g _cat /h after 10 hours of illumination, which is much higher than the catalytic activity of the commercial P25 photocatalyst (CO 0.3 and CH ₄ 0.3 μmol/g _cat /h). In addition, in ₈ cycle experiments on two different plastic surfaces (see Figure 5), the yield of catalytic reduction products CO and CH ₄ decreased by less than 13%, showing good cycle stability.

In summary: The copper bismuthate/calcium bismuthate composite material of the present invention has a stable structure, good solar energy utilization and photocatalytic carbon conversion activity, and has broad application prospects in the fields of photocatalytic _CO2 conversion and waste plastic treatment.

Claims (4)

1. The application of the copper bismuthate/calcium bismuthate composite material in converting hydrocarbon fuel by photocatalysis plastic is characterized in that the copper bismuthate/calcium bismuthate composite material is prepared by the following steps:

1) Dissolving bismuth nitrate pentahydrate and disodium ethylenediamine tetraacetate in an acetic acid solution, then adding absolute ethyl alcohol, and stirring to obtain a clear solution;

2) Adding copper nitrate trihydrate and calcium nitrate tetrahydrate into the clarified solution obtained in the step 1), stirring for 0.5-2h, and then adding sodium hydroxide solution to obtain a copper bismuthate/calcium bismuthate composite material precursor solution;

3) Placing the copper bismuthate/calcium bismuthate composite material precursor solution obtained in the step 2) into an oven for heat preservation, naturally cooling, centrifuging, washing and drying to obtain the copper bismuthate/calcium bismuthate composite material;

In the step 3), the mixture is placed in an oven to be kept at 180-230 ℃ for 6-36h.

2. The use of a copper bismuthate/calcium bismuthate composite according to claim 1, wherein in step 1), 1.94-14.55 g bismuth nitrate pentahydrate and 0.5-6.0 g disodium edetate are dissolved in an acetic acid solution.

3. The application of the copper bismuthate/calcium bismuthate composite material in converting hydrocarbon fuel by photocatalytic plastic according to claim 1, wherein in the step 2), 0.48-3.62 g of copper nitrate trihydrate and 0.16-1.18 g of calcium nitrate tetrahydrate are added.

4. The application of the copper bismuthate/calcium bismuthate composite material in converting hydrocarbon fuel by using photocatalytic plastic according to claim 3, wherein 40-80 mL sodium hydroxide solution with a concentration of 9-11mol/L is added in the step 2).