Amine-functionalized porous mg o / zr o2 composite adsorbents and methods of making the same

Abstract

The present application relates to a kind of amine functionalized porous MgO / ZrO2 Composite adsorbent, tetraethylene pentamine is loaded to porous MgO / ZrO2 Composite adsorbent by impregnation method, and the amine functionalized composite adsorbent with high adsorption capacity obtained by drying has high adsorption capacity.The amine functionalized porous MgO / ZrO2 Composite adsorbent prepared in the present application has good selective adsorption performance for carbon dioxide under normal pressure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas capture, and relates to a kind of adsorbents for carbon dioxide capture, in particular to a kind of zirconium oxide-based composite adsorbents capable of high adsorption capacity of carbon dioxide at normal pressure. BACKGROUND

[0002] The global warming and climate change problem caused by the massive emission of carbon dioxide (CO2) greenhouse gas has become the focus of global attention. Developing CO2 capture and storage technology is one of the important ways to reduce greenhouse gas CO2 emissions and protect the environment.

[0003] Coal-fired power plants are the main fixed emission source of CO2, and the CO2 content in their flue gas is usually between 3-30% (volume fraction), so it is necessary to separate CO2 from the flue gas, concentrate it to high-purity CO2 gas, and then transport it to a specific location for long-term storage through pipelines and other means.

[0004] Currently, the separation and recovery of CO2 from flue gas is mainly based on amine-based solid adsorbents for chemical adsorption, and the adsorption operation usually needs to be carried out at a pressure of 0.1-0.17 MPa. If CO2 can be directly recovered at normal pressure, the cost of capturing CO2 can be saved directly from the source.

[0005] Sohail et al. (Adsorption behavior of tetraethylenepentamine functionalized Si-MCM-41 for CO2 adsorption [J]. Chemical Engineering Research and Design, 2017, 122: 34-42.) modified Si-MCM-41 with tetraethylenepentamine (TEPA) to prepare a solid amine adsorbent. The results showed that when the TEPA loading was 50wt%, the adsorbent showed a maximum CO2 adsorption capacity of 1.6 mmol / g under the adsorption conditions of normal pressure and 75℃.

[0006] Recently, Zhao Peiyu et al. (Preparation of amine-functionalized adsorbents and their CO2 adsorption performance [D]. Taiyuan University of Technology, 2020, 35-42.) reported that by loading TEPA on the surface of porous silica support, an adsorbent with good thermal stability was prepared. The study found that when the TEPA loading reached 60wt%, the maximum CO2 adsorption capacity obtained was 5.01 mmol / g under the adsorption performance test at 75℃ under normal pressure.

[0007] Although the solid amine adsorbents reported in the above documents all obtain a certain amount of CO2 adsorption effect under certain adsorption conditions, according to a large amount of research, it is shown that the structural characteristics of the carrier largely determine the loading effect of the amine and the CO2 adsorption effect thereof. SUMMARY

[0008] The purpose of the present application is to provide an amine functionalized porous MgO / ZrO2 composite adsorbent and a preparation method thereof, by preparing a porous zirconia-based composite adsorption material of a specific structure to load an amine functionalization reagent, so as to realize high CO2 adsorption capacity of the composite adsorbent under normal pressure.

[0009] The amine functionalized porous MgO / ZrO2 composite adsorbent disclosed in the present application is prepared by loading tetraethylenepentamine as an amine functionalization reagent onto the porous MgO / ZrO2 composite adsorbent through an impregnation method, and drying to obtain the composite adsorbent, wherein the porous MgO / ZrO2 composite adsorbent is prepared by using long-chain aliphatic dicarboxylic acid dodecanedioic acid as a dispersant, forming a mixed solution with cationic template agent cetyltrimethylammonium bromide in an ethanol aqueous solution, adding an organic zirconium source to perform solvent evaporation self-assembly to form a zirconium-containing wet gel, and then adding a magnesium salt to mix uniformly to obtain a zirconium-magnesium wet gel, and then high-temperature calcination to obtain the MgO / ZrO2 composite adsorption material.

[0010] Specifically, the organic zirconium source is any one of zirconium n-butylate, zirconium n-propylate or zirconium isopropylate.

[0011] Furthermore, the present application further provides a specific preparation method of the amine functionalized porous MgO / ZrO2 composite adsorbent, which comprises the following steps:

[0012] 1) Dissolve dodecanedioic acid in an ethanol aqueous solution, add cetyltrimethylammonium bromide to obtain a mixed solution, and drop an organic zirconium source to perform solvent evaporation self-assembly reaction to obtain a zirconium-containing wet gel;

[0013] 2) Add a magnesium salt to the zirconium-containing wet gel to obtain a zirconium-magnesium wet gel, dry, and then heat to 550-600℃ for calcination to prepare the porous MgO / ZrO2 composite adsorbent;

[0014] 3) Prepare a tetraethylenepentamine anhydrous ethanol solution, add the porous MgO / ZrO2 composite adsorbent to mix uniformly, and then dry to obtain the amine functionalized porous MgO / ZrO2 composite adsorbent.

[0015] Specifically, in the amine functionalized porous MgO / ZrO2 composite adsorbent prepared by the present application, the mass ratio of the amine functionalization reagent tetraethylenepentamine to the porous MgO / ZrO2 composite adsorbent is 0.3-0.7:1.

[0016] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0017] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0018] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0019] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0020] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0021] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0022] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0023] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0024] Further, in the preparation of the porous MgO / ZrO2 composite adsorbent, the molar ratio of the raw material dodecanedioic acid, cetyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

[0025] The high-adsorption-amount amine functionalized composite adsorbent of the application has the advantages of uniform pore size distribution, high stability, strong regeneration capacity, and small reduction in adsorption amount after multiple cycles of repeated regeneration and use. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is an infrared spectrum of the amine functionalized porous MgO / ZrO2 composite adsorbent.

[0027] Figure 2 is an XRD graph of the amine functionalized porous MgO / ZrO2 composite adsorbent.

[0028] Figure 3 is an SEM graph of the amine functionalized porous MgO / ZrO2 composite adsorbent.

[0029] Figure 4 is an EDS graph of the amine functionalized porous MgO / ZrO2 composite adsorbent.

[0030] Figure 5 is an N2 physical adsorption isotherm graph and pore size distribution graph of the amine functionalized porous MgO / ZrO2 composite adsorbent.

[0031] Figure 6 is a breakthrough curve and adsorption amount graph of the amine functionalized porous MgO / ZrO2 composite adsorbent.

[0032] Figure 7 is a cyclic regeneration performance graph of the amine functionalized porous MgO / ZrO2 composite adsorbent of Example 3. EMBODIMENT

[0033] The specific embodiments of the application are described in further detail below in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the application, so that those skilled in the art can well understand and utilize the application, and are not intended to limit the protection scope of the application.

[0034] The production process, experimental method or detection method involved in the embodiments of the application, if not specifically stated, are conventional methods in the prior art, and the name and / or abbreviation thereof all belong to conventional names in the art, which are very clear and explicit in the related use field, and those skilled in the art can understand the conventional process steps and apply the corresponding equipment according to the conventional conditions or the conditions recommended by the manufacturer.

[0035] The various instruments, equipment, raw materials or reagents used in the embodiments of the application do not have special restrictions on the source, and are conventional products that can be purchased through normal commercial channels, or can be prepared according to the conventional methods well known to those skilled in the art. Example

[0036] Example 1

[0037] Weigh 0.16 g (0.7 mmol) of dodecanedioic acid into a mixture solution of 20 ml of anhydrous ethanol and 2 ml of deionized water, stir at 40 °C for 15 min to obtain a colorless acidic transparent solution, then add 0.5 g (1.4 mmol) of cetyltrimethylammonium bromide, stir at 40 °C for 2 h to obtain a colorless transparent solution.

[0038] Add 3.84 g (10 mmol) of zirconium n-butoxide dropwise to the solution, stir at 40 °C for 20 h to obtain a zirconium-containing wet gel.

[0039] Weigh 0.475 g (1 mmol) of magnesium chloride, add water to just dissolve, and add to the above zirconium-containing wet gel, stir at 40 °C for 4 h to obtain a zirconium-magnesium wet gel.

[0040] The zirconium-magnesium wet gel is suction filtered and washed with anhydrous ethanol 3 times, and then dried at 65 °C for 2 h to obtain a white powder.

[0041] The white powder is heated at a rate of 1 °C / min to 550 °C and calcined for 5 h to prepare a porous MgO / ZrO2 composite adsorbent.

[0042] Weigh 0.3 g of tetraethylenepentamine into 7 ml of anhydrous ethanol, stir at 40 °C for 30 min to obtain an impregnation solution.

[0043] Add 1 g of the above prepared porous MgO / ZrO2 composite adsorbent to the impregnation solution, stir at 40 °C for 5 h to obtain a viscous slurry material, and then heat to 100 °C and dry for 36 h to prepare an amine-functionalized porous MgO / ZrO2 composite adsorbent, denoted as MZ 0.5 -0.3.

[0044] Example 2

[0045] Weigh 0.4 g of tetraethylenepentamine into 7 ml of anhydrous ethanol, stir at 40 °C for 30 min to obtain an impregnation solution.

[0046] Add 1 g of the above prepared porous MgO / ZrO2 composite adsorbent to the impregnation solution, stir at 40 °C for 5 h to obtain a viscous slurry material, and then heat to 100 °C and dry for 36 h to prepare an amine-functionalized porous MgO / ZrO2 composite adsorbent, denoted as MZ 0.5 -0.4.

[0047] Example 3

[0048] Take 0.5g tetraethylene pentamine, add to 7ml anhydrous ethanol, 40℃ stirring 30min to get the impregnation solution.

[0049] 1g porous MgO / ZrO2 composite adsorbent prepared in the above example 1 is added to the impregnation solution, 40℃ stirring 5h, to obtain a viscous slurry material, after drying at 100℃ for 36h, amine functionalized porous MgO / ZrO2 composite adsorbent is prepared, recorded as MZ 0.5 -0.5.

[0050] Example 4

[0051] Take 0.6g tetraethylene pentamine, add to 7ml anhydrous ethanol, 40℃ stirring 30min to get the impregnation solution.

[0052] 1g porous MgO / ZrO2 composite adsorbent prepared in the above example 1 is added to the impregnation solution, 40℃ stirring 5h, to obtain a viscous slurry material, after drying at 100℃ for 36h, amine functionalized porous MgO / ZrO2 composite adsorbent is prepared, recorded as MZ 0.5 -0.6.

[0053] Example 5

[0054] Take 0.7g tetraethylene pentamine, add to 7ml anhydrous ethanol, 40℃ stirring 30min to get the impregnation solution.

[0055] 1g porous MgO / ZrO2 composite adsorbent prepared in the above example 1 is added to the impregnation solution, 40℃ stirring 5h, to obtain a viscous slurry material, after drying at 100℃ for 36h, amine functionalized porous MgO / ZrO2 composite adsorbent is prepared, recorded as MZ 0.5 -0.7.

[0056] The above prepared amine functionalized porous MgO / ZrO2 composite adsorbent is characterized by infrared spectroscopy, the spectrum is shown in Figure 1 The composite adsorbent appears a obvious absorption peak at 3433cm -1 , which is the hydroxyl stretching vibration of the crystal surface adsorbed water; 2922cm -1 and 2834cm -1 The small absorption peaks at 1626cm -1 are respectively attributed to the symmetric stretching vibration peak and asymmetric stretching vibration peak of C-H bond; the absorption peak at 1350cm -1 is attributed to the bending vibration of adsorbed water; the absorption peaks at 900cm -1 and 520cm -1 are attributed to the Zr-O bond vibration absorption peak.

[0057] from Figure 2 It can be seen that the prepared amine-functionalized porous MgO / ZrO2 composite adsorbent exhibits relatively obvious tetragonal phase characteristic diffraction peaks corresponding to the crystal planes (011), (020), and (202) near 2θ=30°, 50°, and 60°. Furthermore, when the TEPA loading reaches 50wt.%, 60wt.%, and 70wt.%, the (011) crystal plane becomes significantly lower and wider, while the diffraction peaks of the (020) and (202) crystal planes gradually disappear. The more TEPA enters the adsorbent channels, the weaker the diffraction peak intensity between the channel walls and the channel interior. This phenomenon indicates that the organic amine has been successfully impregnated into the porous MgO / ZrO2 composite adsorbent material.

[0058] Furthermore, according to Figure 3 The provided adsorbent material MZ 0.5 The scanning electron microscope (SEM) images under different fields of view (-0.3) clearly show that the amine loading makes the pores on the adsorbent surface less obvious. When the amine loading is 30%, some of the pores of the amine-functionalized porous MgO / ZrO2 composite adsorbent are already blocked.

[0059] Continuing to focus on adsorbent material MZ 0.5 EDS analysis was performed at -0.3. Figure 4 The test results show that MZ 0.5 The C atom content in -0.3 is 26.655%, N atom content is 6.130%, O atom content is 48.904%, Mg atom content is 2.758%, and Zr atom content is 15.553%. The presence of C and N elements indicates that TEPA has been successfully loaded onto the porous MgO / ZrO2 composite adsorbent.

[0060] from Figure 5 As can be seen in (a), the isotherms of the amine-functionalized porous MgO / ZrO2 composite adsorbents in each embodiment are concave towards the relative pressure axis, belonging to typical type IV isotherms. Furthermore, an H3-type hysteresis loop appears when the P / P0 value is approximately 0.45–0.99. These isotherm characteristics indicate that intercrystalline mesopores are formed by the accumulation of these amine-functionalized porous MgO / ZrO2 composite adsorbents. When the P / P0 value is below 0.05, MZ... 0.5 The initial adsorption point of -0.3 is higher than that of other adsorbents, and the upward trend is steeper. Furthermore, the vertical axis corresponds to a high adsorption capacity value, indicating that its crystal particles have a larger specific surface area. From... Figure 5 As can be seen in (b), with the increase of amine loading, the micropores in the pore structure of the amine-functionalized porous MgO / ZrO2 composite adsorbent gradually disappear. At low amine concentrations, MZ 0.5 -0.3, MZ 0.5-0.4, MZ 0.5 At -0.5 nm, adsorption was observed to be primarily through micropores of approximately 1.8 nm, with the presence of a small amount of mesopores; while MZ... 0.5 -0.6 and MZ 0.5 The pore structure with a diameter of -0.7 nm is mainly composed of mesopores, which are mainly distributed at around 3.5 nm and 4.5 nm.

[0061]

[0062] Table 1 shows that with the increase of TEPA introduction, the specific surface area and pore volume of the amine-functionalized porous MgO / ZrO2 composite adsorbent decreased significantly compared to the porous MgO / ZrO2 composite adsorbent carrier. This may be because amine entered the pore structure during the impregnation and loading process, causing pore blockage, which is consistent with the XRD analysis above. Compared to the specific surface area of ​​the porous MgO / ZrO2 composite adsorbent (54.89 m²), the pore volume decreased significantly. 2 / g) and pore volume (0.055cm) 3 The specific surface area of ​​the composite adsorbent after amine impregnation is 3.65-8.49 m² / g. 2 The pore volume distribution is between 0.007 and 0.017 cm³ / g. 3 The TEPA concentration is between 0.5 g and 0.5 g, with an average pore size of around 3 nm, indicating that TEPA has been successfully impregnated into the porous MgO / ZrO2 composite adsorbent.

[0063] To demonstrate the adsorption performance of the amine-functionalized porous MgO / ZrO2 composite adsorbent prepared in this invention on carbon dioxide, the adsorbent materials prepared in the above embodiments were taken, and the porous MgO / ZrO2 composite adsorbent without adsorbed amine was used as a control example. The carbon dioxide adsorption performance was tested under normal pressure and adsorption temperature of 75℃. The results are shown in Table 2.

[0064]

[0065] The adsorption data in Table 2 show that, compared with the porous MgO / ZrO2 composite adsorbent of the control example, the selective adsorption performance of CO2 by the amine-functionalized porous MgO / ZrO2 composite adsorbent prepared in each embodiment of the present invention is significantly improved.

[0066] Based on the data in Table 2, further information is provided. Figure 6 The breakthrough curves (a) and adsorption capacity variation trend curves (b) of the five embodiments are shown. It can be seen from the figures that as the TEPA loading increases, the breakthrough time and adsorption capacity of the adsorbent first increase and then decrease, from MZ... 0.5 -0.3, MZ 0.5 -0.4 to MZ 0.5 -0.5, again in MZ 0.5 -0.6, MZ0.5 -0.7 in turn.

[0067] wherein, MZ 0.5 The tail gas CO2 concentration of MZ0.5-0.5 reaches equilibrium in the longest time, and its CO2 adsorption performance is the best, which can reach 4.07 mmol / g. When the TEPA loading continues to increase to 70 wt.%, the CO2 adsorption capacity decreases to 3.88 mmol / g. Although loading more TEPA can provide more active sites, too much TEPA will fill the pores of the adsorbent, reduce the specific surface area and pore volume, increase the resistance of CO2 diffusion, reduce the active sites inside the adsorbent, and thus affect the CO2 adsorption capacity. Therefore, the CO2 adsorption performance of MZ0.5-0.5 is the best.

[0068] Further, the composite adsorbent of Example 3 was subjected to three cyclic regeneration tests, and the results are shown in Table 2. Figure 7 The results show that the selective adsorption of the composite adsorbent for CO2 is 4.07 mmol / g, 4.01 mmol / g and 3.87 mmol / g, respectively, and the CO2 adsorption capacity after three cyclic tests does not change significantly, which is only reduced by 5% compared with the initial adsorption capacity, and the selective adsorption of CO2 can still reach 95% of the initial value, indicating that the adsorbent has good stability and good cyclic regeneration performance.

[0069] The above examples of the present application do not describe all the details, nor limit the present application to only the above described examples. Various changes, modifications, replacements and variations made to these examples by those of ordinary skill in the art without departing from the principles and purposes of the present application shall be included in the protection scope of the present application.

Claims

1. Amine-functionalized porous MgO / ZrO2 composite adsorbent, which is prepared by loading tetraethylenepentamine as an amine functionalization reagent onto a porous MgO / ZrO2 composite adsorbent by an impregnation method, and drying to obtain the composite adsorbent, wherein the porous MgO / ZrO2 composite adsorbent is prepared by forming a mixed solution of a long-chain aliphatic dicarboxylic acid dodecanedioic acid and a cationic template agent hexadecyltrimethylammonium bromide in an aqueous ethanol solution, adding an organic zirconium source to perform solvent evaporation self-assembly to form a zirconium-containing wet gel, adding a magnesium salt to obtain a zirconium-magnesium wet gel, and calcining at a high temperature to obtain the MgO / ZrO2 composite adsorbent.

2. The amine-functionalized porous MgO / Zr02 composite adsorbent of claim 1, wherein The organic zirconium source is any one of zirconium n-butylate, zirconium n-propylate or zirconium isopropylate. 3.A method for preparing the amine-functionalized porous MgO / ZrO2 composite adsorbent according to claim 1, comprising: 1) dissolving dodecanedioic acid in an aqueous ethanol solution, adding hexadecyltrimethylammonium bromide to obtain a mixed solution, and adding an organic zirconium source dropwise to perform solvent evaporation self-assembly to obtain a zirconium-containing wet gel; 2) adding a magnesium salt to the zirconium-containing wet gel to obtain a zirconium-magnesium wet gel, drying, and then calcining at 550-600 DEG C to obtain the porous MgO / ZrO2 composite adsorbent; 3) preparing a tetraethylenepentamine anhydrous ethanol solution, adding the porous MgO / ZrO2 composite adsorbent, and mixing uniformly to obtain the amine-functionalized porous MgO / ZrO2 composite adsorbent after drying.

4. The preparation method of the amine-functionalized porous MgO / ZrO2 composite adsorbent according to claim 3, characterized in that: The mass ratio of the tetraethylenepentamine to the porous MgO / ZrO2 composite adsorbent is 0.3-0.7:

1.

5. The preparation method of the amine-functionalized porous MgO / ZrO2 composite adsorbent according to claim 3, characterized in that: The molar ratio of the dodecanedioic acid, hexadecyltrimethylammonium bromide, organic zirconium source and magnesium salt is 1:2-2.5:12-15:3-12.

6. The preparation method of the amine-functionalized porous MgO / ZrO2 composite adsorbent according to claim 3, characterized in that: The volume ratio of ethanol to water in the aqueous ethanol solution is 8-12:

1.

7. The preparation method of the amine-functionalized porous MgO / ZrO2 composite adsorbent according to claim 3, characterized in that... The zirconium-magnesium wet gel is dried at 60-65 DEG C.

8. The preparation method of the amine-functionalized porous MgO / ZrO2 composite adsorbent according to claim 3, characterized in that... The porous MgO / ZrO2 composite adsorbent is added to the tetraethylenepentamine anhydrous ethanol solution, and stirred at 40 DEG C for 1-5 h to obtain a viscous slurry.

9. The preparation method of the amine-functionalized porous MgO / ZrO2 composite adsorbent according to claim 3, characterized in that: The drying temperature in step 3) is 60-100 DEG C, and the drying time is 24-48 h.

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