A catalyst for the efficient photocatalytic conversion of low-concentration CO2 in converter gas and its preparation method.

Abstract

This invention belongs to the field of catalyst preparation technology, and discloses a catalyst for the efficient photocatalytic conversion of low-concentration CO2 in converter gas and its preparation method. This composite photocatalytic material uses isopropyl titanate, N,N-dimethylformamide, phthalic acid, ionic liquids (ILs), nickel nitrate hexahydrate, ethanol, and dilute nitric acid as main raw materials. A three-phase heterostructure is constructed by adding ILs and NiO, effectively suppressing the recombination of photogenerated electrons and holes. Furthermore, the ionic liquids (ILs) can enrich CO2 components near the catalyst, and NiO can weaken the binding energy of CO on the catalyst surface, thereby enhancing the resistance to CO poisoning. This catalyst is not only simple and inexpensive to prepare, but also effectively acts on low-concentration CO2 in converter gas, increasing the CO concentration by 5-13% and significantly improving the calorific value of the converter gas.

Description

Technical Field

[0001] This invention belongs to the field of photocatalysis, and particularly relates to a method for preparing a catalyst for the efficient photocatalytic conversion of low-concentration CO2 in converter gas. Background Technology

[0002] In the steelmaking process, converter gas is a crucial fuel for enterprises, used for heating water, generating electricity, and baking ladles, among other applications. Its composition is typically: CO ~60%, CO2 ~20%, N2 ~18%, and O2 ~2%. However, due to the short decarburization time during converter smelting, the total amount of converter gas recovered by enterprises is relatively small. Furthermore, the CO2 content in converter gas reaches 20%, resulting in a low calorific value. To address these issues, this invention designs and develops a catalyst preparation method for the efficient photocatalytic conversion of low-concentration CO2 in converter gas.

[0003] Currently, metal-covalent organic frameworks (M-COFs) are formed by anchoring metal ions to the COF framework. They combine the advantages of the open metal centers of MOFs and the stable chemical structure of COFs, while inheriting the porous characteristics of both materials, and are considered a promising new type of CO2 photoreduction catalyst. However, their limited light absorption capacity and susceptibility to CO poisoning in low-concentration CO2 gas mixtures result in poor photocatalytic performance.

[0004] Patent CN115400795B reports an LDH / MOF composite photocatalyst with low-concentration CO2 conversion capability and its preparation method, which utilizes the surface hydroxyl groups (-OH) on the LDH material and the organic ligands on the MOF material to promote the adsorption and enrichment conversion of CO2 gas. However, this catalyst is only suitable for the conversion of low-concentration CO2 and Ar mixed tail gas, and not for the conversion of CO2 in converter gas containing a large amount of CO.

[0005] Patent CN113368902A reports the preparation of a Fe2Co-MOFs-loaded ionic liquid CO2 reduction photocatalyst, utilizing the constructed ILs@PCN-250-Fe2Co with host-guest synergistic effects to exhibit good carbon dioxide adsorption and activation capabilities. However, this catalyst is only used for the reduction of high-purity CO2 gas, and its application to low-concentration CO2 in converter gas has not been studied.

[0006] To address the above problems, this invention proposes a catalyst preparation method for the efficient photocatalytic conversion of low-concentration CO2 in converter gas to increase the CO concentration in converter gas. Summary of the Invention

[0007] To address the aforementioned problems, one objective of this invention is to provide a catalyst for the efficient photocatalytic conversion of low-concentration CO2 in converter gas. This catalyst is a photocatalyst constructed from a three-phase composite material. The three-phase heterostructure of the catalyst is composed of an ionic liquid (IL), NiO, and MIL-125 (Ti). The ionic liquid enriches CO2 molecules in the converter gas near the catalyst reaction sites. Furthermore, the three-phase heterostructure effectively suppresses the recombination of photogenerated electrons and holes, thus efficiently catalytically converting CO2 into CO. Simultaneously, the nano-NiO particles reduce the binding energy of the product CO on the catalyst surface, thereby enhancing the resistance to CO poisoning.

[0008] Another object of the present invention is to provide a method for preparing the above-mentioned catalyst, which is simple and inexpensive.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] In a first aspect, the present invention provides a catalyst for the efficient photocatalytic conversion of low-concentration CO2 in converter gas. The catalyst is a photocatalyst constructed from a three-phase composite material, wherein the three-phase heterostructure of the catalyst is constructed from an ionic liquid (IL), NiO and MIL-125 (Ti).

[0011] In the photocatalyst constructed from the three-phase composite material provided by this invention, the ionic liquid in its three-phase heterostructure can enrich CO2 molecules in converter gas near the catalyst reaction site, effectively suppress the recombination of photogenerated electrons and holes, enhance the desorption of CO and thus avoid catalyst poisoning, thereby improving the catalytic performance of the catalyst under converter gas.

[0012] In a first aspect, this invention provides a method for preparing a catalyst for the efficient photocatalytic conversion of low-concentration CO2 in converter gas. The specific synthesis steps of the catalyst are as follows:

[0013] S1: Add 3-8 mL of methanol and 52-57 mL of N,N-dimethylformamide to an Erlenmeyer flask and stir evenly. Dissolve 3-4 g of terephthalic acid in the resulting solution and stir for 30-45 min. Then add 2-3 mL of isopropyl titanate as a titanium source and stir again for 30-45 min.

[0014] S2: Seal the well-mixed solution from S1 in a 100 mL Teflon-lined stainless steel autoclave and place it in an oven at 120-180 °C for 14-19 h. After the sample cools down, centrifuge the sample and then immerse the centrifuged precipitate in methanol for 10-14 h. Finally, vacuum dry it at 60-100 °C for 10-12 h to obtain the sample MIL-125(Ti).

[0015] S3: Dissolve 3-7 g of the corresponding ionic liquid in n-butanol, wait for it to be uniformly mixed, then mix it with 2-4 g of MIL-125(Ti), stir vigorously for 1 h to obtain solution A;

[0016] S4: Mix 50 mL of Ni (NO3)2·6H2O solution with 200 mL of ethanol and an appropriate amount of dilute nitric acid (volume ratio of ethanol to dilute nitric acid, to obtain mixed solution B);

[0017] S5: Add mixed solution B dropwise to solution A. The resulting colloidal solution is dried in a dust-free environment at room temperature (25 °C) for more than 24 hours to obtain colloidal powder. Then, the colloidal powder is heat-treated under vacuum for 3~7 hours to finally obtain NiO@IL / MIL-125(Ti) material.

[0018] Furthermore, the ionic solution includes, but is not limited to, [BMIm]Cl or [BMIm]Im.

[0019] Furthermore, the volume ratio of ethanol to dilute nitric acid is 0.5 to 2:1.

[0020] Furthermore, the temperature for heat treatment of the colloidal powder is 450~650 °C.

[0021] In summary, the present invention has the following beneficial effects:

[0022] This invention adds IL and NiO to the MIL-125(Ti) metal-organic framework (MoFs) material, which can attract and enrich CO2 and enhance CO desorption, thereby preventing catalyst poisoning and improving the catalytic performance of the catalyst in converter gas. The use of this catalyst can increase the CO concentration in converter gas by 5-13%, thus improving the calorific value of the converter gas.

[0023] This invention constructs a three-phase heterostructure by adding NiO and IL, which effectively expands the photoresponse range of the catalyst, optimizes the separation and transfer of electrons and holes, and promotes the enrichment of CO2 on the catalyst and the rapid desorption of CO, thereby improving the photocatalytic reduction capability of the catalyst under low concentration CO2. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0025] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0026] Example 1

[0027] A method for preparing a catalyst for the efficient photocatalytic conversion of low-concentration CO2 in converter gas includes the following steps:

[0028] S1: Add 6 mL of methanol and 54 mL of N,N-dimethylformamide (DMF) to an Erlenmeyer flask and stir evenly. Dissolve 3.53 g of terephthalic acid in the resulting solution and stir for 30 min. Then add 2.1 mL of isopropyl titanate as a titanium source and stir again for 30 min.

[0029] S2: Seal the well-mixed solution from S1 in a 100 mL Teflon-lined stainless steel autoclave and place it in an oven at 150 °C for 16 h. After the sample cools, centrifuge the sample, then immerse it in methanol for 12 h, and finally vacuum dry it overnight at 80 °C.

[0030] S3: Dissolve 5 g of ionic liquid [Bmim]Cl in 10 mL of n-butanol. Mix the concentrated solution with 3 g of MIL-125(Ti) and stir vigorously for 1 h to obtain solution A.

[0031] S4: Mix 50 mL of Ni(NO3)2·6H2O solution with 200 mL of ethanol and dilute nitric acid (HNO3) (volume ratio of ethanol to dilute nitric acid is 0.5:1) to obtain solution B.

[0032] S5: Add mixture B dropwise to solution A. The resulting colloidal solution is dried in a dust-free environment at room temperature for 24 hours. The colloidal powder is then heated at 550 °C for 4 hours under vacuum to obtain NiO@IL / MIL-125(Ti) material.

[0033] The NiO@IL / MIL-125(Ti) material was placed in a 100 mL gas-phase reactor, and distilled water was added. A mixture of CO2 and CO at concentrations of 40% and 60%, respectively, was then introduced. After a period of xenon lamp irradiation, a portion of the gas in the reactor was extracted and injected into a gas chromatograph to analyze its composition and proportion.

[0034] Tests have shown that this catalyst can increase the CO concentration in converter gas from 60% to 69.2%, which can greatly improve the calorific value of the overall gas composition.

[0035] The comparative experiment used different gas ratios to conduct photocatalytic reduction experiments, and the experimental results are shown in Table 1.

[0036] This invention is applied to photocatalytic CO2 reduction, using a low-concentration CO2 mixture as the gas and pure water as the sacrificial agent. Table 2 shows a comparison of the composition indicators of blast furnace, coke oven, and converter gas.

[0037] Table 1. Comparison of the same catalyst before and after reduction under different gas compositions.

[0038]

[0039] Table 2 Comparison of Composition Indicators of Blast Furnace, Coke Oven, and Converter Gas

[0040]

[0041] The above description is merely an embodiment of the present invention, and common knowledge such as specific technical solutions or characteristics in the solution is not described in detail here. It should be noted that those skilled in the art can make several modifications and improvements without departing from the technical solution of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A catalyst for efficient photocatalytic conversion of low concentration CO2 in converter gas, characterized in that, The catalyst is a photocatalyst constructed by a three-phase composite material, wherein a three-phase heterogeneous structure of the catalyst is constructed by an ionic liquid, NiO and MIL-125(Ti); the ionic solution is [BMIm]Cl or [BMIm]Im; and the catalyst is prepared by the following steps: S1: 3~8 mL of methanol and 52~57 mL of N,N-dimethylformamide are added into a conical flask and uniformly stirred, 3~4 g of terephthalic acid is dissolved in the obtained solution and stirred for 30~45 min, and then 2~3 mL of isopropyl titanate is added as a titanium source and stirred for 30~45 min again; S2: the uniformly mixed solution in S1 is sealed in a 100 mL Teflon-lined stainless steel autoclave, and placed in an oven with a temperature of 120~180 °C for 14~19 h, after the sample is cooled, centrifugal operation is performed on the sample, then the centrifugal precipitate is immersed in methanol for 10~14 h, and finally vacuum drying is performed at 60~100 ℃ for 10~12 h, and the obtained sample is MIL-125(Ti); S3: 3~7 g of the corresponding ionic liquid is dissolved in n-butanol until it is uniformly fused, and then mixed with 2~4 g of MIL-125(Ti) and stirred vigorously for 1 h to obtain solution A; S4: 50 mL of a Ni(NO3)2·6H2O solution is mixed with 200 mL of ethanol and an appropriate amount of dilute nitric acid to obtain a mixed solution B, and the volume ratio of the ethanol and dilute nitric acid is 0.5~2:1; S5: the mixed solution B is added dropwise to the solution A, the formed colloidal solution is dried at room temperature 25 ℃ for more than 24 h in a dust-free environment, and a colloidal powder is obtained, then the colloidal powder is heat treated under vacuum for 3~7 h, and finally the NiO@IL / MIL-125(Ti) material is obtained.

2. The preparation method of a catalyst for efficient photocatalytic conversion of low-concentration CO2 in converter gas according to claim 1, characterized in that, The specific synthesis steps of the catalyst are as follows: S1: 3~8 mL of methanol and 52~57 mL of N,N-dimethylformamide are added into a conical flask and uniformly stirred, 3~4 g of terephthalic acid is dissolved in the obtained solution and stirred for 30~45 min, and then 2~3 mL of isopropyl titanate is added as a titanium source and stirred for 30~45 min again; S2: the uniformly mixed solution in S1 is sealed in a 100 mL Teflon-lined stainless steel autoclave, and placed in an oven with a temperature of 120~180 °C for 14~19 h, after the sample is cooled, centrifugal operation is performed on the sample, then the centrifugal precipitate is immersed in methanol for 10~14 h, and finally vacuum drying is performed at 60~100 ℃ for 10~12 h, and the obtained sample is MIL-125(Ti); S3: 3~7 g of the corresponding ionic liquid is dissolved in n-butanol until it is uniformly fused, and then mixed with 2~4 g of MIL-125(Ti) and stirred vigorously for 1 h to obtain solution A; S4: 50 mL of Ni (NO3)2·6H2O solution is mixed with 200 mL of ethanol and appropriate amount of dilute nitric acid to obtain a mixed solution B, wherein the volume ratio of the ethanol and dilute nitric acid is 0.5-2:1; S5: the mixed solution B is added dropwise into the solution A, the formed colloidal solution is dried at room temperature 25 ℃ for more than 24 h in a dust-free environment, and a colloidal powder is obtained, then the colloidal powder is heat treated under vacuum for 3-7 h, and finally the NiO@ IL / MIL-125(Ti) material is obtained.

3. The method for preparing a catalyst for efficient photocatalytic conversion of low concentration CO2 in converter gas according to claim 2, characterized in that, The volume ratio of the ethanol and dilute nitric acid is 0.5:

1.

4. The preparation method of a catalyst for efficient photocatalytic conversion of low-concentration CO2 in converter gas according to claim 2, characterized in that, The temperature of the heat treatment of the colloidal powder is 450-650 °C. The volume ratio of the ethanol and dilute nitric acid is 0.5:

1. The temperature of the heat treatment of the colloidal powder is 450-650 °C.

Images