A modified mesoporous zirconium oxide adsorbent, its preparation method and use

Abstract

The application discloses a modified mesoporous zirconium oxide adsorbent and a preparation method and application thereof, the modification is amine modification, the adsorbent is marked as OPDx&N-ZrO2, and the nitrogen-doped mesoporous ZrO2 is prepared by using a one-step hydrothermal method; amino acid is used as a template agent and a nitrogen source for nitrogen doping at the same time, zirconium sulfate solution is added drop by drop into the amino acid solution, after stirring, the solution is aged at room temperature, the hydrothermal treatment is carried out, the solution is washed by deionized water until neutral, then the solution is dried at 90 DEG C for 10h, finally, the solution is calcined in two stages, the nitrogen-doped mesoporous ZrO2 is prepared by using the one-step hydrothermal method, then o-phenylenediamine and the nitrogen-doped mesoporous ZrO2 carrier are dissolved in ethanol, the solution is stirred at normal temperature, the solution is subjected to microwave reaction in subcritical ethanol for 15min, the solution is dried at 75 DEG C, and the amine-modified nitrogen-doped mesoporous ZrO2 adsorbent for CO2 capture can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon capture, and in particular relates to a modified mesoporous zirconia adsorbent for CO2 capture, and a preparation method and application thereof. Background Art

[0002] The latest data from the Global Carbon Project, an international climate science organization, indicates that global carbon dioxide emissions are likely to reach a new historical record in 2022. As one of the most prominent greenhouse gases, excessive CO2 emissions are causing increasingly severe environmental pollution problems, necessitating urgent carbon reduction. Currently, there are three primary approaches to CO2 reduction: adjusting industrial structure, reducing fossil fuel use, and CO2 capture technology. The first two approaches have been declining in research due to high investment costs, long implementation cycles, and limited scope of application, as well as suboptimal emission reduction results. However, CO2 adsorption technology, with its advantages of simple operation, low technical costs, and low regeneration energy consumption, has become the most effective means of CO2 emission reduction. The preparation and modification of adsorbents have also become new research hotspots.

[0003] Mesoporous materials have a very high specific surface area (>1000 m 2 ZrO2, with its excellent properties such as high pore volume ( / g) and pore volume, regular and ordered pore structure, continuously adjustable pore size, and controllable pore wall composition and properties, has become a research hotspot in the adsorption field. Unlike common metal oxide adsorbents such as TiO2 and SiO2, ZrO2 is chemically stable and insoluble in common acids and bases. Its surface is rich in oxygen vacancies and acid-base amphoteric sites, making it not only catalytically active but also an ideal carrier material for various catalytically active components.

[0004] Mesoporous zirconia is generally synthesized by hydrothermal synthesis using polyethylene glycol or hexadecyltrimethylammonium bromide as templates. In order to obtain a modified mesoporous ZrO2 with high selectivity, high thermal stability and improved CO2 adsorption capacity, experts and scholars have conducted many experiments such as heteroatom doping and amine modification. However, there are few reports on the process of preparing nitrogen-doped mesoporous zirconia using amino acids and Zr(SO4)2·4H2O. Studies have found that the amino groups in amino acids react with Zr 4+ No effect occurs. The carboxyl groups in L-glutamic acid and L-arginine react with Zr 4+The amino acid not only acts as a reaction template but also as a nitrogen source, achieving the purpose of nitrogen doping during preparation. Tetraethylenepentamine, ethylenediamine, and polyethyleneimine, which are commonly used for amine modification, do not have hydrophobic properties. However, carbon dioxide gas usually contains water vapor that may occupy adsorption sites, so the adsorbent needs to be hydrophobically modified. Therefore, choosing a hydrophobic organic amine for modification can achieve both hydrophobic modification and basic group modification, while improving the material's water resistance and adsorption capacity for CO2 adsorption. Summary of the Invention

[0005] In view of the incompleteness of the existing technology, the present invention provides a modified mesoporous zirconia adsorbent for CO2 capture and a preparation method thereof, so as to solve the problems of low stability and poor adsorption capacity of the currently prepared mesoporous zirconia.

[0006] In order to solve the existing problems, the technical solution adopted by the present invention is:

[0007] A modified mesoporous zirconia adsorbent is modified to be amine-modified. The adsorbent is labeled OPDx&N-ZrO2, wherein x refers to the mass ratio of o-phenylenediamine to N-ZrO2, and x=0.15-0.45; N-ZrO2 is nitrogen-doped mesoporous zirconia.

[0008] A method for preparing a modified mesoporous zirconia adsorbent comprises the following steps:

[0009] Step 1: dissolving an amino acid and an inorganic zirconium source in a molar ratio of 1:0.33 in deionized water, adding the zirconium salt solution dropwise to the amino acid solution, stirring vigorously, and aging at room temperature for 2-3 hours;

[0010] Step 2: The product obtained in step 1 is placed in a polytetrafluoroethylene autoclave, subjected to hydrothermal treatment at 110°C for 12 hours, washed with ethanol, dried in an oven at 90°C for 10 hours, and ground to obtain a powder; finally, the obtained powder is calcined for 6 hours to obtain nitrogen-doped mesoporous ZrO2, denoted as N-ZrO2;

[0011] Step 3: dissolve o-phenylenediamine and N-ZrO2 in a carrier in 10 mL of ethanol, stir at room temperature for 9 h, microwave-react in subcritical ethanol at 200 ° C and below 6 MPa for 15 min, and then dry at 75 ° C for 12 h to obtain the target product.

[0012] In step 1, the inorganic zirconium source is Zr(SO4)2·4H2O, and the amino acid is glycine.

[0013] The calcination in step 2 is divided into two stages. The first stage is calcination at 235° C. for 3 hours to decompose glycine to form nitrogen-containing intermediates. The second stage is calcination at 500° C. for 3 hours to remove the template and complete nitrogen doping.

[0014] The invention discloses an application of a modified mesoporous zirconia adsorbent for CO2 capture or adsorption.

[0015] The beneficial technical effects of the present invention are as follows: the present invention is a modified mesoporous zirconia adsorbent for CO2 capture and a preparation method thereof, which is prepared by a hydrothermal synthesis process, and glycine is added as a template during the preparation process. Glycine can serve as both a reaction template and a nitrogen source. Therefore, during the formation of mesoporous ZrO2, glycine decomposes and simultaneously achieves the purposes of pore formation and nitrogen doping, thereby realizing a one-step hydrothermal process for preparing nitrogen-doped mesoporous ZrO2. Compared with the general two-step method of first hydrothermally synthesizing mesoporous ZrO2 and then nitrogen doping, the reaction steps are simplified and the reaction time is shortened; the prepared nitrogen-doped mesoporous ZrO2 has a high specific surface area, pore volume and abundant surface oxygen vacancies, providing an excellent matrix for subsequent modification. Finally, nitrogen-doped ZrO2 was modified with amines using o-phenylenediamine (OPD) microwave reaction in subcritical ethanol. O-phenylenediamine is a hydrophobic organic amine that is both active and stable. Subcritical ethanol allows OPD to be highly dispersed on the surface of the material, providing more effective adsorption sites and improving the material's adsorption selectivity, adsorption capacity and water resistance for CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The XRD patterns of the products obtained in Examples 1-3 and Comparative Examples of the present invention are as follows;

[0017] Figure 2 This is a diagram showing the CO2 cyclic adsorption and desorption performance of the product obtained in Example 2 of the present invention. Implementation Method

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0019] (1) Glycine and Zr(SO4)2·4H2O were dissolved in 50 mL of deionized water at a ratio of 1:0.33. The Zr(SO4)2·4H2O solution was added dropwise to the amino acid solution with vigorous stirring, and then aged at room temperature for 2–3 h.

[0020] (2) Place in a polytetrafluoroethylene autoclave, react at 110°C for 12 hours, wash with ethanol, and then dry in an oven at 90°C for 10 hours. Grind to obtain a powder. Finally, the obtained powder is calcined at 235°C and 500°C for 3 hours to obtain nitrogen-doped mesoporous ZrO2.

[0021] (3) 0.075 g of o-phenylenediamine and 0.5 g of the prepared carrier ZrO2 were dissolved in 10 mL of ethanol, stirred at room temperature for 9 h, microwaved in subcritical ethanol at 200 °C and below 6 MPa for 15 min, and then dried at 75 °C for 12 h to obtain the target sample, which was labeled as OPD. 0.15 &N-ZrO2. Example 2

[0022] (1) Glycine and Zr(SO4)2·4H2O were dissolved in 50 mL of deionized water at a ratio of 1:0.33. The Zr(SO4)2·4H2O solution was added dropwise to the amino acid solution with vigorous stirring, and then aged at room temperature for 2–3 h.

[0023] (2) Place in a polytetrafluoroethylene autoclave, react at 110°C for 12 hours, wash with ethanol, and then dry in an oven at 90°C for 10 hours. Grind to obtain a powder. Finally, the obtained powder is calcined at 235°C and 500°C for 3 hours to obtain nitrogen-doped mesoporous ZrO2.

[0024] (3) Dissolve 0.15g of o-phenylenediamine and 0.5g of the prepared carrier ZrO2 in 10mL of ethanol, stir at room temperature for 9h, microwave-react in subcritical ethanol at 200℃ and below 6Mpa for 15min, and then dry at 75℃ for 12h to obtain the target OPD. 0.3 &N-ZrO2. Example 3

[0025] (1) Glycine and Zr(SO4)2·4H2O were dissolved in 50 mL of deionized water at a ratio of 1:0.33. The Zr(SO4)2·4H2O solution was added dropwise to the amino acid solution with vigorous stirring, and then aged at room temperature for 2–3 h.

[0026] (2) Place in a polytetrafluoroethylene autoclave, react at 110°C for 12 hours, wash with ethanol, and then dry in an oven at 90°C for 10 hours. Grind to obtain a powder. Finally, the obtained powder is calcined at 235°C and 500°C for 3 hours to obtain nitrogen-doped mesoporous ZrO2.

[0027] (3) 0.225 g of o-phenylenediamine and 0.5 g of the prepared carrier ZrO2 were dissolved in 10 mL of ethanol, stirred at room temperature for 9 h, microwaved for 15 min in subcritical ethanol at 200 °C and below 6 MPa, and then dried at 75 °C for 12 h to obtain the target sample, which was labeled as OPD. 0.45 &N-ZrO2. Comparative Example 1

[0028] (1) Glycine and Zr(SO4)2·4H2O were dissolved in 50 mL of deionized water at a ratio of 1:0.33. The Zr(SO4)2·4H2O solution was added dropwise to the amino acid solution with vigorous stirring, and then aged at room temperature for 2–3 h.

[0029] (2) The mixture was placed in a polytetrafluoroethylene autoclave and reacted at 110°C for 12 h. The mixture was washed with ethanol and then dried in an oven at 90°C for 10 h. The powder was ground and calcined at 235°C and 500°C for 3 h, respectively, to obtain nitrogen-doped mesoporous ZrO2. The obtained sample was labeled N-ZrO2, where N-ZrO2 is mesoporous zirconia prepared with glycine. Comparative Example 2

[0030] (1) CTAB and Zr(SO4)2·4H2O were dissolved in 50 mL of deionized water at a ratio of 1:0.33. Zr(SO4)2·4H2O solution was added dropwise to the CTAB solution with vigorous stirring, and then aged at room temperature for 2–3 h.

[0031] (2) Place the mixture in a polytetrafluoroethylene autoclave and react at 110°C for 12 hours. Wash with ethanol and then dry in an oven at 90°C for 10 hours. Grind the mixture to obtain a powder. Finally, calcine the powder at 500°C for approximately 6 hours to obtain mesoporous ZrO2. The resulting sample is labeled as ZrO2.

[0032] X-ray diffraction (XRD) analysis of the samples was performed using an XD-3 diffractometer. The scanning range was 2θ = 10° to 80°, and the scanning speed was 10° / min. Figure 1 The XRD patterns of the prepared mesoporous ZrO2 and the modified mesoporous ZrO2 are shown in the figure. As can be seen from the figure, the diffraction peaks at 2θ are 30.20°, 35.13°, 50.41° and 60.0°. Referring to the standard JCPDS card (card number: 50-1089), they belong to the (011), (110), (112) and (121) crystal planes of t-ZrO2, and the prepared support is mesoporous ZrO2. The results show that the positions of the diffraction peaks are all shifted to the right, indicating that the lattice parameter of zirconium oxide has become smaller. This is caused by the doping of nitrogen atoms, which have a smaller radius than the zirconium atom. No impurity peaks were detected within the detection limit of XRD, indicating that the prepared material is nitrogen-doped mesoporous ZrO2.

[0033] After the nitrogen-doped mesoporous ZrO2 was modified with o-phenylenediamine, the shape of its XRD diffraction peak was found to have almost no change. This phenomenon indicates that the nitrogen-doped mesoporous ZrO2 structure after amination modification still maintains its original stability. However, during the modification process, OPD 0.15&N-ZrO2, the diffraction peaks at 2θ angles of 50.41° and 60.00° shifted to 50.42° and 60.08°, respectively; OPD 0.3 &N-ZrO2, the diffraction peaks at 2θ angles of 35.13° and 50.41° shifted to 35.20° and 50.42°, respectively; OPD 0.45 &N-ZrO2, the diffraction peaks at 2θ angles of 50.41° and 60.00° shifted to 50.44° and 60.05° respectively. When o-phenylenediamine was used to modify nitrogen-doped mesoporous ZrO2, o-phenylenediamine reacted with the surface of nitrogen-doped mesoporous ZrO2, causing the diffraction peak of the material to shift. With the increase of o-phenylenediamine loading, the surface of nitrogen-doped mesoporous ZrO2 was covered by o-phenylenediamine molecules, and the crystallinity of the material surface gradually decreased, so the diffraction peak intensity gradually decreased. 0.3 &N-ZrO2, OPD 0.45 The diffraction peak intensity of N-ZrO2 did not decrease significantly, which may be due to the unsatisfactory crystallinity of the material during the loading process. In summary, the XRD results show that nitrogen-doped mesoporous ZrO2 and its modified materials were successfully prepared.

[0034] Taking CO2 with a volume fraction of 20% as the adsorbent, the OPD 0.15 &N-ZrO 2、 OPD 0.3 &N-ZrO2 and OPD 0.45 The dynamic adsorption performance of CO2 on &N-ZrO2 was investigated to find the optimal amine loading. This experiment used two adsorption methods: dynamic adsorption and desorption, and static adsorption and desorption. The airflow rate was controlled at 10 mL / min, and CO2 adsorption tests were carried out at 20°C, 40°C, and 60°C to investigate the optimal adsorption temperature. 1.0 g of amine-modified sample was filled into a supported U-shaped tube. The airflow was controlled at a flow rate of 10 mL / min. The supported U-shaped tube was removed and weighed every 2 minutes. The mass data of the adsorbent was recorded. The above experiment was repeated until the weight did not change for more than 5 consecutive times. The experiment was stopped and the adsorption process was completed. The data obtained from the experiment are shown in Table 1.

[0035] Table 1 ZrO2, N-ZrO2 and OPD x CO2 adsorption-desorption performance of N-ZrO2

[0036] adsorbent Air flow rate mL / min Adsorption temperature ℃ Adsorption capacity mg.g -1 ]] Zr02 10 20 121 [N-ZrO2] 10 20 147 OPD 0.15 &N-ZrO2 10 20 178 OPD 0.3 &N-ZrO2 10 20 196 OPD 0.45 &N-ZrO2]] 10 20 183 OPD 0.3 &N-ZrO2 10 40 215 OPD 0.3 &N-ZrO2 10 60 238

[0037] When the adsorption temperature is 20℃, the CO2 adsorption capacity of N-ZrO2 is 147 mg / g, and the CO2 adsorption capacity of the three OPD modified samples are 178 mg / g, 196 mg / g and 183 mg / g, which are increased by 21.1%, 33.3% and 24.5% respectively. 0.3 &N-ZrO2 has the best adsorption performance. When the loading exceeds a certain amount, OPD will agglomerate and clog the pores of nitrogen-doped mesoporous ZrO2, resulting in a decrease in its specific surface area and exposed chemical adsorption sites, thereby reducing the adsorption performance. 0.3 The CO2 adsorption capacity of N-ZrO2 at 40℃ and 60℃ increased to 215 mg / g and 238 mg / g, respectively, indicating that the optimal adsorption temperature is 60℃. When the temperature is higher than 60℃, the molecular motion is intense, resulting in an increase in the desorption rate and a decrease in the adsorption performance.

[0038] In application, the ideal adsorbent should not only have a high adsorption capacity for CO2, but also have good cyclic adsorption and desorption performance and water resistance. 0.3 Taking N-ZrO2 as an example, dry and water-containing CO2 gas (20%) was introduced at 60℃, and after CO2 adsorption was saturated, CO2 was desorbed in a 100℃ water bath under nitrogen purge conditions. The cycle adsorption-desorption test was repeated 5 times. The results are as follows: Figure 2 After 5 cycles of adsorption and desorption under dry conditions, the CO2 adsorption capacity dropped to 228 mg / g, and the adsorption decay rate was only 4.2%, indicating that the OPD-modified nitrogen-doped mesoporous ZrO2 has good cyclic adsorption and desorption performance; after 5 cycles of adsorption and desorption under water vapor conditions, the CO2 adsorption capacity dropped to 208 mg / g, and the adsorption decay rate was only 12.6%, indicating that the OPD-modified nitrogen-doped mesoporous ZrO2 also has good water resistance.

Claims

1. A modified mesoporous zirconia adsorbent, characterized in that The modification is amine-modified, and the adsorbent is labeled as OPDx&N-ZrO2, wherein x refers to the mass ratio of o-phenylenediamine to N-ZrO2, and x=0.15-0.45; N-ZrO2 is nitrogen-doped mesoporous zirconia. The preparation method of the adsorbent is as follows: step 1, dissolving an amino acid and an inorganic zirconium source at a molar ratio of 1:0.33 in deionized water, adding the zirconium salt solution dropwise to the amino acid solution, stirring vigorously and aging at room temperature for 2-3 hours, wherein the amino acid is glycine; step 2, charging the product obtained in step 1 into a polytetrafluoroethylene autoclave, hydrothermally treating it at 110°C for 12 hours, and then washing it with ethanol. , dried in an oven at 90°C for 10 hours, ground to obtain a powder, and finally calcined the obtained powder for 6 hours to obtain nitrogen-doped mesoporous ZrO2, recorded as N-ZrO2, wherein the calcination is divided into two stages, the first stage is calcined at 235°C for 3 hours to decompose glycine to form a nitrogen-containing intermediate, and the second stage is calcined at 500°C for 3 hours to remove the template and complete nitrogen doping at the same time; step 3, o-phenylenediamine and N-ZrO2 are dissolved in 10mL of ethanol, stirred at room temperature for 9 hours, microwaved at 200°C and subcritical ethanol below 6Mpa for 15 minutes, and then dried at 75°C for 12 hours to obtain the target product.

2. A method for preparing a modified mesoporous zirconia adsorbent, characterized in that: The following steps are involved: Step 1: dissolving an amino acid and an inorganic zirconium source in a molar ratio of 1:0.33 in deionized water, adding the zirconium salt solution dropwise to the amino acid solution, stirring vigorously, and aging at room temperature for 2 to 3 hours, wherein the amino acid is glycine; Step 2: The product obtained in step 1 was placed in a polytetrafluoroethylene autoclave, subjected to hydrothermal treatment at 110°C for 12 hours, washed with ethanol, dried in an oven at 90°C for 10 hours, and ground to obtain a powder; finally, the obtained powder was calcined for 6 hours to obtain nitrogen-doped mesoporous ZrO2, recorded as N-ZrO 2， The calcination is divided into two stages: the first stage is calcination at 235°C for 3 hours to decompose glycine to form nitrogen-containing intermediates; the second stage is calcination at 500°C for 3 hours to remove the template and complete nitrogen doping; Step 3: dissolve o-phenylenediamine and N-ZrO2 in 10 mL of ethanol, stir at room temperature for 9 h, microwave react in subcritical ethanol at 200 ° C and below 6 MPa for 15 min, and then dry at 75 ° C for 12 h to obtain the target product.

3. The method for preparing the modified mesoporous zirconia adsorbent according to claim 2, characterized in that The inorganic zirconium source in step 1 is Zr(SO4)2·4H2O.

4. Use of the modified mesoporous zirconia adsorbent according to claim 1 for CO2 capture or adsorption.

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