A Cu-based material for CO adsorption 2 Preparation method of OC adsorbent

Abstract

The present invention discloses a preparation method of a Cu2O-C adsorbent for CO adsorption, which relates to the technical field of CO adsorbent synthesis. In the present invention, copper nitrate, polyvinylpyrrolidone, squaric acid, and oxalic acid are used to first prepare a calcination precursor of a light green precipitate, followed by calcination and reduction to obtain a cuprous oxide / carbon nanocomposite material. Among them, with a specific ratio of polyvinylpyrrolidone, squaric acid, and oxalic acid, the prepared metal-organic framework material (MOF) is used as a precursor, which can highly disperse the adsorption center Cu, and the carbon material after carbonization has a high specific surface area and a tunable pore structure, which can provide more adsorption sites, thereby improving the adsorption effect; the present invention belongs to a renewable adsorbent, including materials that can be regenerated under mild conditions and renewable adsorbents, so as to improve the regeneration efficiency and stability of the adsorbent.

Description

Technical Field

[0001] The present invention relates to the technical field of CO adsorbent synthesis, and in particular to a Cu 2+ adsorbent for CO adsorption. 2 Preparation method of OC adsorbent. Background Art

[0002] Carbon monoxide (CO) is a colorless, odorless, non-irritating gas. It is one of the main gas components produced by incomplete or insufficient combustion of fuels, which may come from home heating systems, automobile exhaust, industrial processes or fires. Although CO exists in nature, high concentrations of CO are very harmful to humans and the environment, specifically in the following aspects:

[0003] 1. Health hazards: High concentrations of CO can enter the human blood and bind to hemoglobin, preventing the delivery of oxygen to body tissues, leading to hypoxia. This may cause headaches, dizziness, nausea, vomiting, loss of consciousness, and even death. The risk of CO poisoning is higher for people with fragile bodies, such as the elderly, children, pregnant women, and heart patients.

[0004] 2. Environmental impact: CO reacts with other chemicals in the environment to form pollutants such as ozone and particulate matter. These pollutants have a negative impact on air quality and ecosystems, affecting plant growth and animal ecological balance.

[0005] Therefore, people should strengthen their awareness of CO and take appropriate protective and preventive measures to reduce the risk of CO poisoning and environmental pollution. This involves the adsorption of CO, and the most critical technology is to provide a suitable adsorbent. 2 OC adsorbent has certain advantages in CO adsorption, among which cuprous ions play an important role in the adsorption process. Its working principle is shown in the following formula:

[0006]

[0007] In the π-complexation mechanism, CO can both donate electrons and be donated electrons. + Both the empty s orbital can be donated electrons, and the d orbital of carbon monoxide can be filled with electrons. + When forming chemical bonds, Cu + The empty 4s orbital of the CO molecule overlaps with the electrons provided by the 2(5σ) or 4(5σ+1π) orbital of the CO molecule to form the σ component; while the empty anti-2π bond orbital of CO and the electrons provided by the 2(5σ) or 4(5σ+1π) orbital of the CO molecule overlap to form the σ component. + The 3d orbital heavy orbitals are filled in the Cu +The binding ability of CuO is enhanced to form a very stable complex, which can be used to achieve the adsorption of CO. However, the adsorption capacity of the above adsorbents for CO is still not ideal. After multiple adsorption and desorption cycles, the adsorption performance also changes greatly. Therefore, how to further improve the CuO 2 Improving the adsorption capacity of OC adsorbents and extending their lifespan are our key research topics. Summary of the invention

[0008] The present invention aims to provide a Cu for CO adsorption 2 Preparation method of OC adsorbent to solve the existing Cu 2 The technical problem is that the adsorption capacity of OC adsorbent is not ideal and the adsorption life is low.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] A Cu-based material for CO adsorption 2 The preparation method of OC adsorbent comprises the following steps:

[0011] (1) Dissolve copper nitrate in deionized water;

[0012] (2) adding 1.5 to 2 times the mass of polyvinyl pyrrolidone as much as the copper nitrate to the copper nitrate solution obtained in step (1), heating to 40 to 60° C., and stirring until completely dissolved;

[0013] (3) adding 1.5 times the molar amount of copper nitrate of squaric acid and the same molar amount of oxalic acid dropwise to the solution system obtained in step (2), and stirring until completely dissolved;

[0014] (4) transferring the solution obtained in step (3) into a reaction tank, heating to 140-160° C., and continuing the reaction for 2-4 hours;

[0015] (5) filtering the reaction solution obtained in step (4) to obtain a light green precipitate, washing it, and then drying it;

[0016] (6) Under a nitrogen atmosphere, calcining the solid obtained in step (5) at 700-750° C. for 1-2 hours at a heating rate of 1-5° C. / min;

[0017] (7) Ultrasonic dispersion of the black powder obtained by calcining step (6) into water, slowly stirring, and dropwise adding zinc borohydride solution until no bubbles are generated, filtering, and drying to obtain Cu 2 OC adsorbent.

[0018] Preferably, the average molecular weight of the polyvinyl pyrrolidone in step (2) is 30,000.

[0019] Preferably, in step (5), the solvents for washing the light green precipitate are deionized water and n-hexane, and the deionized water and n-hexane are used for washing three times each.

[0020] Preferably, in step (6), the heating rate is 3°C / min.

[0021] Preferably, in step (7), the concentration of the zinc borohydride solution is 0.1 mol / L.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention uses a metal organic framework material (MOF) prepared by using specific reagents and their proportions as a precursor, which can highly disperse the adsorption center Cu, and the carbon material after carbonization has a high specific surface area and a controllable pore structure, which can provide more adsorption sites, thereby improving the adsorption effect;

[0024] 2. The present invention relates to a regenerable adsorbent, including materials and regenerable adsorbents that can be regenerated under mild conditions to improve the regeneration efficiency and stability of the adsorbent.

[0025] 3. The raw materials of the present invention are safe and easy to obtain, the production cost is low, the process flow is convenient, the operation is simple, and it is conducive to engineering promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The bar graph is a graph showing the adsorption performance of the adsorbents obtained by reducing the active centers with different reducing agents;

[0027] Figure 2 The bar graph is a graph showing the adsorption performance of adsorbents prepared using different metal active centers;

[0028] Figure 3 Cu prepared by using different molar ratios of squaric acid and oxalic acid 2 Bar graph of adsorption performance of OC adsorbent;

[0029] Figure 4 Cu prepared at different heating rates during calcination 2 Bar graph of adsorption performance of OC adsorbent;

[0030] Figure 5 Cu on different supports 2 O adsorption performance bar graph of adsorbents;

[0031] Figure 6 Cu obtained in Example 1 2 Line graph of the adsorption performance of OC adsorbent during multiple adsorption and desorption cycles. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with various embodiments and drawings. The implementation of the present invention includes but is not limited to the following embodiments.

[0033] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0035] In the following examples, different catalysts were prepared under different reaction conditions and their catalytic activities were verified.

[0036] The adsorption performance test process of the adsorbent obtained by the present invention is as follows: the CO adsorption test of the sample is obtained by the American Micromeritics ASAP 2020 test, the test temperature is 25°C, and the pressure range is 1atm. Before the gas adsorption experiment, about 100 mg of the sample must be degassed at 150°C in a degassing station for 24 hours. After the degassing is completed and weighed, it is transferred to the ASAP2020 adsorption instrument analysis station for gas static adsorption test.

[0037] Example 1

[0038] The preparation process of the catalyst in this embodiment is as follows:

[0039] (1) 1.87 g of copper nitrate Cu(NO 3 ) 2 of in 20 mL of deionized water.

[0040] (2) Add 3 g of polyvinyl pyrrolidone (molecular weight about 30,000) to the above solution, heat to 50°C, and stir until completely dissolved.

[0041] (3) Add 1.71 g of squaric acid and 1.35 g of oxalic acid dropwise to the above solution and stir until completely dissolved.

[0042] (4) The above solution was placed in a reaction tank lined with polytetrafluoroethylene and heated to 150°C for 2 h.

[0043] (5) The reaction solution was filtered to obtain a light green precipitate, which was washed three times with deionized water and three times with n-hexane, and then dried at 110° C. for 1 h.

[0044] (6) The precipitation in N 2In the atmosphere, the temperature was raised to 700°C at a rate of 3°C / min and continued for 1 hour until black powder

[0045] (7) The black powder was dispersed into water by ultrasonication, stirred slowly, and 0.1 mol / L zinc borohydride solution was added dropwise until no bubbles were generated to obtain Cu 2 O / C adsorbent.

[0046] Example 2

[0047] This example discusses the effect of treating metal active centers with different reducing agents on adsorption performance: under the same reaction conditions as in Example 1, zinc borohydride was used to replace nickel borohydride, sodium borohydride, lithium borohydride, and hydrogen, and the adsorbents obtained were subjected to adsorption capacity tests respectively with the adsorbents obtained in Example 1. The adsorption performance of each group of adsorbents was measured as follows: Figure 1 It can be seen that the adsorbent obtained by using zinc borohydride as a reducing agent has better adsorption performance.

[0048] Example 3

[0049] This example discusses the effect of different metal active centers on adsorption performance: Under the same reaction conditions as in Example 1, Cu + Replaced by Cu 2+ (Not reduced), Cr 2+ Cr 3+ , Fe 2+ , Fe 3+ The obtained adsorbent and the adsorbent obtained in Example 1 were subjected to adsorption capacity experiments respectively, and the adsorption performance of each group of adsorbents was measured as follows: Figure 2 As shown. It can be seen that Cu + The adsorption performance of the adsorbent is more advantageous.

[0050] Example 4

[0051] This example discusses the effect of different ligand ratios on adsorption performance: Under the same reaction conditions as in Example 1, 1.71 g of squaric acid and 1.35 g of oxalic acid (molar ratio 1:1) were replaced with ligands in the ratios shown in Table 1:

[0052] Table 1 Addition amount of different molar ratios of squaric acid and oxalic acid

[0053] Squaric acid:oxalic acid SA / OAratio (molar ratio) Squaric acid / g Oxalic acid / g 1:0 3.42 0 2:1 2.28 0.9 1:2 1.14 1.8 0:1 0 2.7

[0054] The obtained adsorbent and the adsorbent obtained in Example 1 were subjected to adsorption capacity experiments respectively, and the adsorption performance of each group of adsorbents was measured as follows: Figure 3 As shown, it can be seen that the adsorbent prepared by the molar ratio of 1:1 ligand ratio has obvious advantages in adsorption performance, and other ratios may even reduce the adsorption performance.

[0055] Example 5

[0056] This example discusses the effect of different heating rates during calcination on adsorption performance: under the same reaction conditions as in Example 1, 3°C / min was replaced by 1°C / min, 2°C / min, 5°C / min, 10°C / min, and 20°C / min, respectively. The adsorbents obtained were subjected to adsorption capacity tests with the adsorbents obtained in Example 1, and the adsorption performance of each group of adsorbents was measured as follows: Figure 4 As shown. It can be seen that when the temperature rises more than 3℃ / min, Cu 2 The adsorption performance of OC adsorbent decreased.

[0057] Example 6

[0058] This example discusses the effect of different carriers on adsorption performance: Cu / AC, Cu / Al 2 O 3 , Cu / SBA-15 and Cu / MCM-41, and Cu was prepared according to the following scheme 2 OC-ref adsorbent:

[0059] (1) 100 mL of 0.2 mol / L copper chloride solution and 150 mL of 0.26 mol / L sodium salicylate aqueous solution were uniformly mixed, and 0.5 mol / L NaOH aqueous solution was slowly added after stirring. After adjusting the pH of the system to 6.5, the mixture was reacted at 80° C. in an argon atmosphere for 48 h. The product was centrifuged, washed and dried to obtain a one-dimensional salicylate intercalated layered copper hydroxide precursor.

[0060] (2) The precursor prepared in the above step was calcined at 600° C. for 5 min in a nitrogen atmosphere to obtain a one-dimensional Cu / C nanocomposite material.

[0061] (3) The nanocomposite material prepared in step (2) is placed in an oxygen atmosphere and calcined at 200° C. for 10 min to obtain a cuprous oxide / carbon nanocomposite material, denoted as Cu 2 O / C-ref adsorbent.

[0062] The above-obtained adsorbent and the adsorbent obtained in Example 1 were subjected to adsorption capacity tests respectively, and the adsorption performance of each group of adsorbents was measured as follows: Figure 5 As shown. It can be seen that the present invention uses a metal organic framework material (MOF) prepared by specific reagents and their proportions as a precursor to calcine the prepared Cu 2 The adsorption performance of O / C adsorbent is better.

[0063] Example 7

[0064] In this example, the adsorbent obtained in Example 1 was subjected to multiple adsorption and desorption cycles, that is, each desorption was carried out in a degassing station at 150°C for 24 hours in vacuum, and then tested again. The adsorption performance of each test was as follows: Figure 6 As shown, it can be seen that the adsorbent prepared in Example 1 of the present invention has almost no attenuation in adsorption performance after multiple adsorptions, and the adsorbent has a long life.

[0065] The above embodiment is only one of the preferred implementation modes of the present invention and should not be used to limit the protection scope of the present invention. Any changes or modifications that are made to the main design concept and spirit of the present invention and have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention.

Claims

1. A Cu for CO adsorption 2 Preparation method of OC adsorbent, It is characterized in that The steps include: Dissolve copper nitrate in deionized water; Add 1.5 to 2 times the mass of polyvinyl pyrrolidone as much as the copper nitrate to the copper nitrate solution obtained in step (1), heat to 40 to 60° C., and stir until completely dissolved; Add 1.5 times the molar amount of copper nitrate of squaric acid and the same molar amount of oxalic acid as squaric acid dropwise to the solution system obtained in step (2), and stir until completely dissolved; The solution obtained in step (3) is transferred into a reaction tank, heated to 140-160°C, and the reaction is continued for 2-4 hours; The reaction solution obtained in step (4) is filtered to obtain a light green precipitate, which is then washed and then dried; Under a nitrogen atmosphere, calcining the solid obtained in step (5) at 700-750° C. for 1-2 hours at a heating rate of 1-5° C. / min; The black powder obtained by calcining step (6) is ultrasonically dispersed in water, slowly stirred, and zinc borohydride solution is dripped into it until no bubbles are generated. Cu 2 OC adsorbent.

2. The preparation method according to claim 1, It is characterized in that The average molecular weight of the polyvinyl pyrrolidone in step (2) is 30,000.

3. The preparation method according to claim 1, It is characterized in that In step (5), the solvents for washing the light green precipitate are deionized water and n-hexane, and the deionized water and n-hexane are used for washing three times respectively.

4. The preparation method according to claim 1, It is characterized in that In step (6), the heating rate is 3°C / min.

5. The preparation method according to claim 1, It is characterized in that In step (7), the concentration of the zinc borohydride solution is 0.1 mol / L.

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