Preparation method of ordered defect type indium cluster frame porous material for converting carbon dioxide into urea through electro-catalysis

Abstract

The invention discloses a preparation method of an ordered defect type indium cluster frame porous material for converting carbon dioxide into urea through electro-catalysis, belongs to the field of technical equipment for synthesizing an ordered defect type metal organic frame, and particularly relates to a preparation method of an ordered defect type indium cluster frame material for preparing urea through electro-catalysis reduction of CO2. Comprising five steps. According to the design, the ordered defect type indium cluster frame porous material is synthesized by adopting a hydrothermal synthesis mode and taking indium trifluoromethanesulfonate as a metal source and adopting an in-situ self-assembly method, and the preparation method disclosed by the invention can be used for preparing the ordered defect type indium cluster frame porous material. The obtained product indium cluster frame porous material has uniform micron-sized size and excellent stability, the method used in the invention is simple to operate, the obtained catalyst has ordered defects, and the catalyst shows excellent selectivity in preparation of urea through electrocatalytic reduction of carbon dioxide under low overpotential, and has good application prospects. The method is difficult to realize by the existing metal organic framework-based catalyst at present.

Description

Technical Field

[0001] The invention belongs to the field of technical equipment for synthesizing ordered defective metal organic frameworks, and particularly relates to a method for preparing an ordered defective indium cluster framework material for electrocatalytic reduction of CO2 to prepare urea. Background Art

[0002] Converting greenhouse gas carbon dioxide into high-value chemicals through electrochemical reduction is an effective solution to alleviate the energy crisis. Carbon dioxide reduction is the conversion of carbon dioxide into single-carbon products (carbon monoxide, formic acid, methane, etc.) and multi-carbon products (ethanol, acetic acid, ethylene, etc.) through 2-12 electrons. Despite significant progress in the field of carbon dioxide, the products generated are still limited to single C or CC coupled chemicals. Exploring new pathways for electrocatalytic carbon dioxide reduction has become an important task in the field of electrocatalysis, with the aim of diversifying the products generated from carbon dioxide. At present, valuable CN coupled compounds (urea) have been successfully synthesized from carbon dioxide and waste nitrogen-containing species (nitrates) on the earth, expanding the range of product categories beyond pure carbon dioxide reduction. And the application of urea in agriculture, chemical synthesis and medicinal chemistry is of considerable significance.

[0003] Metal-organic frameworks (MOFs) are widely used in electrocatalytic carbon dioxide reduction due to their high specific surface area, flexible and adjustable structure, and easy functionalization. Common strategies such as doping, acidification, and pyrolysis are used to construct defects to improve the catalytic activity of materials. However, the preparation of defects in MOF materials is random, and it is difficult to accurately construct defects in MOFs.

[0004] Therefore, a new technical solution is needed in the prior art to solve this problem urgently. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an optimization upgrade for existing components in the background technology.

[0006] A method for preparing an ordered defective indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea, characterized in that it comprises the following steps, and the following steps are performed in sequence:

[0007] Step 1, weighing a metal salt, wherein the metal salt is indium trifluoromethanesulfonate, and placing the weighed metal salt into a polytetrafluoroethylene liner of a high-pressure reactor;

[0008] Step 2, weighing an organic ligand, wherein the organic ligand is an asymmetric organic ligand, and placing the weighed ligand into a polytetrafluoroethylene liner of a high-pressure reactor;

[0009] Step 3: Place the organic solvent into the polytetrafluoroethylene liner of the autoclave and stir at room temperature for 2 hours;

[0010] Step 4: tighten the high-pressure reactor in step 3 and place it in an oven, heat the oven to 80-120° C., react at 80-120° C. for 48 hours, and then naturally cool the oven to 10-25° C. to obtain an ordered defective indium cluster framework porous material;

[0011] Step 5: Rinse the ordered defective indium cluster framework porous material generated by the reaction in step 4 with deionized water and acetonitrile, and place it in a centrifuge tube to dry naturally to obtain a pure ordered defective indium cluster framework porous material.

[0012] The amount of the organic ligand used in step 2 is half the mass of the metal salt.

[0013] The asymmetric organic ligand comprises one of isonicotinic acid and isophthalic acid having a substituent at the 2nd position of the benzene ring.

[0014] The isonicotinic acid having a substituent at position 2 of the benzene ring includes isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, 2-bromoisonicotinic acid and the like.

[0015] The organic solvents used in step three are mainly acetonitrile and N,N-dimethylformamide.

[0016] Through the above design, the present application adopts a hydrothermal synthesis method with indium trifluoromethanesulfonate as a metal source and an in situ self-assembly method to synthesize an ordered defective indium cluster framework porous material. The preparation method of the present application can order the defective indium cluster framework porous material, and the obtained product indium cluster framework porous material has a uniform micron-level size and excellent stability. The method used in the present application is simple to operate, and the obtained catalyst has ordered defects. It shows excellent selectivity for preparing urea by electrocatalytic reduction of carbon dioxide at a relatively low overpotential, which is difficult to achieve with the currently available metal organic framework-based catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0018] Figure 1 , a 200um dimension diagram of the ordered defective indium cluster framework porous material prepared by the invention;

[0019] Figure 2 , is a comparison diagram of LSV curves of the present invention under CO2 / Ar atmosphere;

[0020] Figure 3 , is the product distribution diagram of the present invention at different potentials;

[0021] Figure 4 , is a comparison diagram of urea products in the CO2 / Ar atmosphere of the present invention;

[0022] Figure 5 , for the present invention 15 N NMR. DETAILED DESCRIPTION

[0023] The present application is further described with reference to the accompanying drawings:

[0024] A method for preparing an ordered defective indium cluster framework porous material for electrocatalytic conversion of CO2 to urea, characterized in that it comprises the following steps, and the following steps are performed in sequence:

[0025] Step 1, weighing a metal salt, wherein the metal salt includes indium trifluoromethanesulfonate, and placing the weighed metal salt into a polytetrafluoroethylene liner of a high-pressure reactor;

[0026] Step 2, weighing an organic ligand, wherein the organic ligand is an asymmetric organic ligand, and placing the weighed ligand into a polytetrafluoroethylene liner of a high-pressure reactor;

[0027] Step 3: Place the organic solvent into the polytetrafluoroethylene liner of the autoclave and stir at room temperature for 2 hours;

[0028] Step 4: tighten the high-pressure reactor in step 3 and place it in an oven, heat the oven to 80-120° C., react at 80-120° C. for 48 hours, and then naturally cool the oven to 10-25° C. to obtain an ordered defective indium cluster framework porous material;

[0029] Step 5: Rinse the ordered defective indium cluster framework porous material generated by the reaction in step 4 with deionized water and acetonitrile, and place it in a centrifuge tube to dry naturally to obtain a pure ordered defective indium cluster framework porous material.

[0030] The amount of the organic ligand used in step 2 is half the mass of the metal salt.

[0031] The asymmetric organic ligand comprises one of isonicotinic acid and isophthalic acid having a substituent at the 2nd position of the benzene ring.

[0032] The isonicotinic acid having a substituent at position 2 of the benzene ring includes isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, 2-bromoisonicotinic acid and the like.

[0033] The organic solvents used in step three are mainly acetonitrile and N,N-dimethylformamide.

[0034] Example 1

[0035] Accurately weigh 15 mg of indium trifluoromethanesulfonate and 7.5 mg of ligand isonicotinic acid and put them into the polytetrafluoroethylene liner of the autoclave, add 3 ml of acetonitrile (AR), and stir for 2 hours. Put the polytetrafluoroethylene liner into the autoclave and tighten it, put the autoclave into the oven, heat the oven to 80°C, and react at 80°C for 48 hours, then wait for the oven to cool down to 10°C naturally, wash the synthesized ordered defective MOF with 3 ml of deionized water and 3 ml of acetonitrile alternately, and put the washed crystals into a 2 ml centrifuge tube to dry naturally. The morphology of the prepared ordered defective MOF is as follows: Figure 1 shown.

[0036] Embodiment 2:

[0037] Accurately weigh 20 mg of indium trifluoromethanesulfonate and 10 mg of ligand 2-chloroisonicotinic acid and put them into the polytetrafluoroethylene liner of the autoclave, add 5 ml of acetonitrile (AR), and stir for 2 hours. Put the polytetrafluoroethylene liner into the autoclave and tighten it, put the autoclave into the oven, heat the oven to 120°C, and react at 120°C for 48 hours, then wait for the oven to cool down to 25°C naturally, wash the synthesized ordered defective MOF with 3 ml of deionized water and 3 ml of acetonitrile alternately, and put the washed crystals into a 2 ml centrifuge tube to dry naturally.

[0038] Embodiment 3:

[0039] Accurately weigh 16 mg of indium trifluoromethanesulfonate and 8 mg of ligand 2-hydroxyisonicotinic acid and put them into the polytetrafluoroethylene liner of the autoclave, add 3.5 ml of acetonitrile (AR), and stir for 2 hours. Put the polytetrafluoroethylene liner into the autoclave and tighten it, put the autoclave into the oven, heat the oven to 100 ° C, and react at 100 ° C for 48 hours, then wait for the oven to cool down to 10 ° C naturally, wash the synthesized ordered defective MOF with 3 ml of deionized water and 3 ml of acetonitrile alternately, and put the washed crystals into a 2 ml centrifuge tube to dry naturally.

[0040] Embodiment 4:

[0041] Accurately weigh 16 mg of indium trifluoromethanesulfonate and 8 mg of ligand 2-aminoisonicotinic acid and put them into the polytetrafluoroethylene liner of the autoclave, add 4 ml of acetonitrile (AR), and stir for 2 hours. Put the polytetrafluoroethylene liner into the autoclave and tighten it, put the autoclave into the oven, heat the oven to 100 ° C, and react at 100 ° C for 48 hours, then wait for the oven to cool down to 25 ° C naturally, wash the synthesized ordered defective MOF with 3 ml of deionized water and 3 ml of acetonitrile alternately, and put the washed crystals into a 2 ml centrifuge tube to dry naturally.

[0042] Embodiment 5:

[0043] Accurately weigh 20 mg of indium trifluoromethanesulfonate and 10 mg of ligand 2-bromoisonicotinic acid and put them into the polytetrafluoroethylene liner of the autoclave, add 5 ml of acetonitrile (AR), and stir for 2 hours. Put the polytetrafluoroethylene liner into the autoclave and tighten it, put the autoclave into the oven, heat the oven to 120°C, and react at 120°C for 48 hours, then wait for the oven to cool down to 25°C naturally, wash the synthesized ordered defective MOF with 3 ml of deionized water and 3 ml of acetonitrile alternately, and put the washed crystals into a 2 ml centrifuge tube to dry naturally.

[0044] Embodiment 6:

[0045] Accurately weigh 20 mg of indium trifluoromethanesulfonate and 10 mg of ligand isophthalic acid and put them into the polytetrafluoroethylene liner of the autoclave, add 5 ml of N,N-dimethylformamide (AR), and stir for 2 hours. Put the polytetrafluoroethylene liner into the autoclave and tighten it, put the autoclave into the oven, heat the oven to 120°C, and react at 120°C for 48 hours, then wait for the oven to cool down to 25°C naturally, wash the synthesized ordered defective MOF with 3 ml of deionized water and 3 ml of acetonitrile alternately, and put the washed crystals into a 2 ml centrifuge tube to dry naturally.

[0046] The present invention is simple to operate and can generate ordered defective indium cluster framework porous materials in situ. Figure 1 Taking the structure shown as an example, it has excellent selectivity for the electrocatalytic reduction of carbon dioxide to produce urea at a lower overpotential. In the case of potassium bicarbonate containing 1 mg / ml KNO3 as the electrolyte, CO2 can be converted into urea at a voltage of -0.4 V vs RHE, and the selectivity of the carbon product is 100%.

[0047] The electrosynthesis activity of urea from the porous framework containing defective indium clusters was evaluated in a 0.1 M KHCO3 solution saturated with CO2 and containing 1 mg / ml. Figure 2 As shown, compared with the Ar environment, the overpotential in the CO2 atmosphere is significantly reduced and the current density is significantly increased, indicating that it has the ability to prepare urea from CO2.

[0048] like Figure 3 As shown, the prepared urea product has a volcano-shaped distribution, and a maximum selectivity of 70% for urea and 100% for carbon for CO2 are observed at -0.4 V vs RHE, which are among the values ​​reported for electrocatalysts.

[0049] In order to further evaluate the source of urea, control tests and isotope experiments were performed to prove the successful preparation of urea.

[0050] The ordered defective indium cluster framework porous material catalyst obtained in the present application has a lower overpotential and a higher selectivity in catalyzing CO2 reduction to prepare urea. At a potential of -0.4V vs RHE, CO2 can be converted into urea with a selectivity of 100% for carbon products.

[0051] Figure 1 This is a picture of the product of this application at a size of 200um.

Claims

1. A method for preparing an ordered defective indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea, characterized in that: The process includes the following steps, which are performed in sequence: Step 1, weighing a metal salt, wherein the metal salt includes indium trifluoromethanesulfonate, and placing the weighed metal salt into a polytetrafluoroethylene liner of a high-pressure reactor; Step 2, weighing an organic ligand, wherein the organic ligand is an asymmetric organic ligand, and placing the weighed ligand into a polytetrafluoroethylene liner of a high-pressure reactor; Step 3: Place the organic solvent into the polytetrafluoroethylene liner of the autoclave and stir at room temperature for 2 hours; Step 4: tighten the high-pressure reactor in step 3 and place it in an oven, heat the oven to 80-120° C., react at 80-120° C. for 48 hours, and then naturally cool the oven to 10-25° C. to obtain an ordered defective indium cluster framework porous material; Step 5: Rinse the ordered defective indium cluster framework porous material generated by the reaction in step 4 with deionized water and acetonitrile, and place it in a centrifuge tube to dry naturally to obtain a pure ordered defective indium cluster framework porous material.

2. The method for preparing the ordered defective indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea according to claim 1, characterized in that: The amount of the organic ligand used in step 2 is half the mass of the metal salt.

3. The method for preparing the ordered defective indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea according to claim 1, characterized in that: The asymmetric organic ligand comprises one of isonicotinic acid and isophthalic acid having a substituent at the 2nd position of the benzene ring.

4. The method for preparing the ordered defective indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea according to claim 3, characterized in that: The isonicotinic acid having a substituent at position 2 of the benzene ring includes isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, 2-bromoisonicotinic acid and the like.

5. The method for preparing the ordered defective indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea according to claim 1, characterized in that: The organic solvents used in step three are mainly acetonitrile and N,N-dimethylformamide.

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