MOFs adsorbent of cumene as well as preparation method and application of MOFs adsorbent

Abstract

The invention discloses an MOFs adsorbent of cumene and a preparation method and application thereof, and belongs to the technical field of adsorbent preparation, and the preparation method comprises the following steps: step 1, preparing an MIL-101 adsorbent; 2, the MIL-101 adsorbent is soaked in a thiocyanate solution for 10 min to 30 min, centrifugation, washing and drying are conducted, and the MOFs adsorbent of isopropyl benzene is obtained. The adsorption capacity of the MIL-101 adsorbent post-treated by the sodium thiocyanate to cumene gas is remarkably improved. Due to the introduction of sodium thiocyanate, a new functional group is grafted, and a new adsorption site is introduced, so that the adsorption capacity of the adsorbent on cumene gas is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorbent preparation, and specifically relates to a MOFs adsorbent for cumene and a preparation method and application thereof. Background Art

[0002] MOFs (Metal Organic Frameworks) are organic-inorganic nanomaterials with intramolecular voids formed by self-assembly of organic ligands and metal ions or clusters through coordination bonds. This material has the characteristics of large porosity, large specific surface area, and strong structural flexibility, so it exhibits excellent adsorption performance and has become a hot topic in current research and application.

[0003] MIL-101 is a metal organic framework (MOF) material. MIL-101 has extremely high specific surface area and pore volume, which makes it have excellent performance in gas adsorption, storage and catalysis. Although MIL-101 has a certain adsorption capacity for a variety of pollutants (such as heavy metal ions, pesticides, antibiotics, etc.), its adsorption selectivity may not be as good as some other materials. In some adsorption applications that require high selectivity, MIL-101 may not be the best choice. The regeneration performance of MIL-101 still needs to be improved. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0005] As one aspect of the present invention, the present invention provides a method for preparing a MOFs adsorbent of cumene, which comprises the following steps:

[0006] Step 1, preparing MIL-101 adsorbent;

[0007] Step 2: soak the MIL-101 adsorbent in a thiocyanate solution for 10 to 30 minutes, centrifuge, wash, and dry to obtain a MOFs adsorbent for cumene.

[0008] As a preferred embodiment of the preparation method of the MOFs adsorbent for isopropylbenzene described in the present invention: in step 1, the preparation method of the MIL-101 adsorbent includes adding terephthalic acid and chromium nitrate nonahydrate into water, heating to 180-190° C. for 6-8 hours, cooling, centrifuging, and washing to obtain the MIL-101 adsorbent.

[0009] As a preferred embodiment of the method for preparing the MOFs adsorbent for cumene described in the present invention: in step 1, the molar ratio of terephthalic acid to chromium nitrate nonahydrate is 1:0.8-1.2.

[0010] As a preferred solution of the method for preparing the MOFs adsorbent for cumene described in the present invention: in step 1, the heating rate is 3-4°C / min.

[0011] As a preferred embodiment of the method for preparing the MOFs adsorbent for cumene of the present invention: in step 1, the cooling comprises cooling to room temperature at a rate of 4 to 5°C / min.

[0012] As a preferred embodiment of the method for preparing the MOFs adsorbent for cumene of the present invention: in step 2, the thiocyanate includes sodium thiocyanate; and the concentration of the thiocyanate solution is 0.8 to 0.12 mol / L.

[0013] As a preferred solution of the preparation method of the MOFs adsorbent for cumene described in the present invention: in step 2, the MIL-101 adsorbent is immersed in the thiocyanate solution for 10 to 30 minutes; the mass ratio of the MIL-101 adsorbent to thiocyanate is 1:0.3 to 0.4.

[0014] As a preferred embodiment of the method for preparing the MOFs adsorbent for cumene of the present invention: in step 2, the washing includes washing with deionized water.

[0015] The present invention also provides the MOFs adsorbent prepared by the preparation method of the MOFs adsorbent of cumene.

[0016] The present invention also provides the use of the MOFs adsorbent prepared by the preparation method of the MOFs adsorbent for cumene in adsorbing cumene gas.

[0017] Beneficial effects of the present invention: The adsorption capacity of the MlL-101 adsorbent after sodium thiocyanate post-treatment for cumene gas is significantly improved. Due to the introduction of sodium thiocyanate, new functional groups are grafted and new adsorption sites are introduced, thereby significantly improving the adsorption capacity of the adsorbent for cumene gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following briefly introduces the drawings required for describing the embodiment, wherein:

[0019] Figure 1 This is the X-ray diffraction image of MIL-101 adsorbent post-treated with sodium thiocyanate;

[0020] Figure 2 This is a scanning electron microscope image of the MlL-101 adsorbent post-treated with sodium thiocyanate;

[0021] Figure 3This is the infrared spectrum of MIL-101 adsorbent post-treated with sodium thiocyanate. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0023] Test method: The dynamic column breakthrough curve measurement method was used to test the adsorption capacity of each adsorbent for cumene. The test conditions were normal temperature and pressure. The adsorption column was a heat-resistant quartz glass tube with an inner diameter of 7 mm and a length of 490 mm. 0.05 g of the adsorbent of Examples 1 to 3 or Comparative Examples 1 to 7 was added to the adsorption column. The concentration of cumene gas was 500 ppm, the flow rate was 30 mL / min, and the atmosphere was nitrogen. The cumene concentration of the outlet gas was detected by gas chromatography.

[0024] Embodiment 1:

[0025] 0.83 g of terephthalic acid and 2 g of chromium nitrate nonahydrate were added to 30 mL of deionized water, stirred and mixed, and then ultrasonically mixed at 28°C for 26 min to obtain a precursor solution, which was added to a stainless steel autoclave and heated to 190°C at a heating rate of 3°C / min and kept warm for 8 h, cooled to room temperature at a rate of 4.8°C / min, centrifuged at 5000 rpm for 30 min, and the supernatant was discarded. The precipitate was collected, N, N-dimethylformamide was added to the precipitate, washed at 66°C for 2.5 h, and centrifuged at 6800 rpm for 10 min, the supernatant was discarded, the precipitate was collected, methanol was added, washed at 63°C for 2.5 h, and centrifuged at 6000 rpm for 6 min, the precipitate was dried in an oven at 60°C for 14 h, and the precipitate was ground clockwise at a uniform speed in a mortar to obtain a uniform green MIL-101 powder.

[0026] A sodium thiocyanate solution with a concentration of 0.1 mol / L was prepared, 0.3 g of MIL-101 powder was dissolved in 15 ml of sodium thiocyanate solution, stirred and mixed, and then allowed to stand and soak for 20 minutes. The mixed solution was placed in a centrifuge, centrifuged at 6000 rpm for 9 minutes, the supernatant was discarded, deionized water was added to the centrifuge tube for washing, centrifuged at 6000 rpm for 9 minutes, the supernatant was discarded again, deionized water was added to the centrifuge tube for washing, centrifuged at 6000 rpm for 9 minutes, the supernatant was discarded again, deionized water was added to the centrifuge tube containing the precipitate for washing, and centrifuged at 6000 rpm for 9 minutes. This was done three times, and the obtained solid was placed in a 79°C oven for air drying for 14 hours, and then ground into a uniform powder in a mortar clockwise at a uniform speed. The obtained adsorbent sample was recorded as MIL-SCN2.

[0027] The adsorption capacity of cumene gas by the adsorbent MIL-SCN2 prepared in Example 1 was measured to be 426 mg / g. The adsorption capacity of MIL-SCN2 was restored to 97% by pyrolysis regeneration at 70°C, and after 5 cycles of regeneration, the adsorption capacity was still maintained above 90%.

[0028] Embodiment 2:

[0029] MIL-101 powder was prepared according to the method of Example 1, and a 0.1 mol / L sodium thiocyanate solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of sodium thiocyanate solution, stirred and mixed, and then allowed to stand and soak for 10 minutes. The subsequent experimental steps were consistent with those of Example 1. The prepared sample was recorded as MIL-SCN1. The adsorption capacity of the adsorbent for cumene gas was measured to be 402 mg / g.

[0030] Embodiment 3:

[0031] MIL-101 powder was prepared according to the method of Example 1, and a 0.1 mol / L sodium thiocyanate solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of sodium thiocyanate solution, stirred and mixed, and then allowed to stand and soak for 30 minutes. The subsequent experimental steps were consistent with Example 1. The prepared sample was recorded as MIL-SCN3. The adsorption capacity of the adsorbent for cumene gas was measured to be 394 mg / g.

[0032] The present invention has found that the grafting time of thiocyanate should not be too long, as excessive grafting may lead to the destruction of the pore structure and excessive merging of pores, resulting in a decrease in adsorption capacity.

[0033] Comparative Example 1:

[0034] 0.12g sodium thiocyanate, 0.83g terephthalic acid and 2g chromium nitrate nine hydrate were added to 30mL deionized water, stirred and mixed, ultrasonically mixed at 28℃ for 26min to obtain a precursor solution, added to a stainless steel autoclave, heated to 190℃ at a heating rate of 3℃ / min and kept warm for 8h, cooled to room temperature at a rate of 4.8℃ / min, centrifuged at 5000rpm for 30min, discarded the supernatant, collected the precipitate, added N,N-dimethylformamide to the precipitate, washed at 66℃ for 2.5h, centrifuged at 6800rpm for 10min, discarded the supernatant, collected the precipitate, added methanol, washed at 63℃ for 2.5h, centrifuged at 6000rpm for 6min, dried the precipitate in a 60℃ oven for 14h, and ground the precipitate clockwise at a uniform speed with a mortar to obtain a uniform green powder. The adsorption capacity of the adsorbent for isopropylbenzene gas was measured to be 197mg / g. The adsorbent was pyrolyzed and regenerated at 70°C, and its adsorption capacity could be restored to 72%, and after 5 cycles of regeneration, its adsorption capacity dropped to 35%.

[0035] Comparative Example 2:

[0036] MIL-101 powder was prepared according to the method of Example 1, and 0.1 mol / L sodium hydroxide solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of sodium hydroxide solution, stirred and mixed, and then allowed to stand and soak for 20 minutes. The subsequent experimental steps were consistent with Example 1. The adsorption capacity of the adsorbent for cumene gas was 186 mg / g.

[0037] Comparative Example 3:

[0038] MIL-101 powder was prepared according to the method of Example 1, and 0.1 mol / L citric acid solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of citric acid solution, stirred and mixed, and then allowed to stand and soak for 20 minutes. The subsequent experimental steps were consistent with Example 1. The adsorption capacity of the adsorbent for cumene gas was 145 mg / g.

[0039] Comparative Example 4:

[0040] MIL-101 powder was prepared according to the method of Example 1, and 0.1 mol / L sulfonamide solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of sulfonamide solution, stirred and mixed, and then allowed to stand and soak for 20 minutes. The subsequent experimental steps were consistent with Example 1. The adsorption capacity of the adsorbent for cumene gas was 213 mg / g.

[0041] Comparative Example 5:

[0042] MIL-101 powder was prepared according to the method of Example 1, and a 0.1 mol / L p-phenylenediamine solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of p-phenylenediamine solution, stirred and mixed, and then allowed to stand and soak for 20 minutes. The subsequent experimental steps were consistent with Example 1. The adsorption capacity of the adsorbent for cumene gas was 173 mg / g.

[0043] Comparative Example 6:

[0044] MIL-101 powder was prepared according to the method of Example 1, and 0.1 mol / L methylamine hydrochloride solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of methylamine hydrochloride solution, stirred and mixed, and then allowed to stand and soak for 20 minutes. The subsequent experimental steps were consistent with Example 1. The adsorption capacity of the adsorbent for cumene gas was 186 mg / g. The adsorbent was pyrolyzed and regenerated at 70°C, and the adsorption capacity was restored to 29%.

[0045] Comparative Example 7:

[0046] MIL-101 powder was prepared according to the method of Example 1, and a 0.1 mol / L hydroxyethylethylenediamine solution was prepared. 0.3 g of MIL-101 powder was dissolved in 15 ml of the hydroxyethylethylenediamine solution, stirred and mixed, and then allowed to stand and soak for 20 minutes. The subsequent experimental steps were consistent with Example 1. The adsorption capacity of the adsorbent for cumene gas was 149 mg / g.

[0047] like Figure 1 As shown, the XRD diffraction pattern of the MIL-101 adsorbent post-treated with sodium thiocyanate exhibits characteristic peaks at 2θ values ​​of 5.21°, 5.64°, 5.88°, 8.47°, 9.08°, 9.09°, and 16.51°, which are consistent with the characteristic peaks of the MIL-101 structure, indicating that the MIL-101 structure was successfully synthesized.

[0048] like Figure 2 As shown, after sodium thiocyanate post-treatment, it was observed that the MOFs adsorbent post-treated with sodium thiocyanate maintained the morphological characteristics of MIL-101.

[0049] like Figure 3 As shown, the infrared spectrum of the adsorbent proves that thiocyanate is successfully grafted into the MIL-101 material, demonstrating the effectiveness of the sodium thiocyanate post-treatment.

[0050] Experimental results: The adsorption capacity of the adsorbents prepared in each embodiment and comparative example for isopropylbenzene gas was tested according to the above method. It can be seen from the experimental results that the breakthrough time of the MIL-101 adsorbent after sodium thiocyanate post-treatment for isopropylbenzene gas adsorption was significantly prolonged. The breakthrough time of MlL-SCN2 prepared in Example 1 reached 180min (the breakthrough time of MlL-101 adsorbent was 130min). It is speculated that the reason is that the grafting of thiocyanate makes the isopropylbenzene gas fully contact the active sites of the adsorbent. The adsorption capacity of the MIL-101 adsorbent after sodium thiocyanate post-treatment of the present invention is significantly improved. Specifically, the adsorption capacity of MIL-SCN2 prepared in the embodiment reaches 426mg / g, while the adsorption capacity of MIL-101 is 294mg / g. Due to the introduction of sodium thiocyanate, new functional groups are grafted and new adsorption sites are introduced, which significantly improves the adsorption amount of isopropylbenzene gas.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a MOFs adsorbent for cumene, characterized in that: The following steps are included: Step 1, preparing MIL-101 adsorbent; Step 2: soak the MIL-101 adsorbent in a thiocyanate solution for 10 to 30 minutes, centrifuge, wash, and dry to obtain a MOFs adsorbent for cumene.

2. The method for preparing the MOFs adsorbent of cumene according to claim 1, characterized in that: In step 1, the preparation method of the MIL-101 adsorbent includes adding terephthalic acid and chromium nitrate nonahydrate into water, heating to 180-200° C. for 6-8 hours, cooling, centrifuging, and washing to obtain the MIL-101 adsorbent.

3. The method for preparing the MOFs adsorbent of cumene according to claim 2, characterized in that: In step 1, the molar ratio of terephthalic acid to chromium nitrate nonahydrate is 1:0.8-1.

2.

4. The method for preparing the MOFs adsorbent of cumene according to claim 2, characterized in that: In step 1, the heating rate is 3-4°C / min.

5. The method for preparing the MOFs adsorbent of cumene according to claim 2, characterized in that: In step 1, the cooling includes cooling to room temperature at a rate of 4-5°C / min.

6. The method for preparing a MOFs adsorbent for cumene according to any one of claims 1 to 5, characterized in that: In step 2, the thiocyanate includes sodium thiocyanate; and the concentration of the thiocyanate solution is 0.8 to 0.12 mol / L.

7. The method for preparing a MOFs adsorbent for cumene according to any one of claims 1 to 5, characterized in that: In step 2, the MIL-101 adsorbent is immersed in the thiocyanate solution for 10 to 30 minutes; the mass ratio of the MIL-101 adsorbent to the thiocyanate is 1:0.3 to 0.

4.

8. The method for preparing a MOFs adsorbent for cumene according to any one of claims 1 to 5, characterized in that: In step 2, the washing includes washing with deionized water. 9 . The MOFs adsorbent prepared by the method for preparing the MOFs adsorbent for cumene according to claim 1 . 10 . Use of the MOFs adsorbent prepared by the method for preparing the MOFs adsorbent for cumene according to claim 1 in adsorbing cumene gas.

Images