Preparation method and application of functional group modified titanium-based metal-organic framework material MIP-207

Abstract

This invention discloses a method for preparing a titanium-based metal-organic framework material (MIP-207) modified with various functional groups, and its application in the field of catalytic oxidative fuel desulfurization. The present invention's preparation method is simple. The functionally group-modified organic ligands are replaced with the original ligands in a certain proportion, and the functionally group-modified MIP-207 catalyst is synthesized in a single step using a reflux method. The catalyst is applied to catalytic oxidative fuel desulfurization, featuring a simple reaction system, mild reaction conditions, and a short reaction time. It also exhibits superior catalytic oxidative desulfurization performance, meeting the needs of deep desulfurization and green chemical industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel catalysts, and in particular relates to a preparation method of a functional group-modified titanium-based metal organic framework material MIP-207 and its application in catalytic oxidation desulfurization of fuel at room temperature. Background Art

[0002] During fuel combustion, sulfur oxides (SOx) are released into the atmosphere through vehicle exhaust, causing a range of environmental problems, including smog and acid rain. Consequently, countries and regions around the world have enacted legislation to limit the concentration of sulfur compounds in oil products, with increasingly stringent standards. Currently, hydrodesulfurization (HDS) is commonly used in industry to remove sulfur compounds from oil products. However, HDS requires demanding reaction conditions, requiring high temperatures and pressures for deep desulfurization, consuming large amounts of hydrogen, and degrading oil quality. To overcome the limitations of HDS in removing thiophene sulfides from oil products, oxidative desulfurization can be used. Oxidative desulfurization involves the use of an oxidant to oxidize thiophene sulfides to their corresponding thiophene sulfones in the presence of a catalyst. This allows the highly polar sulfone sulfides to be separated from the non-polar oil product, ultimately removing sulfur compounds from the oil. The catalytic effect of the catalyst plays a crucial role in oxidative desulfurization.

[0003] Metal-organic frameworks (MOFs) are organic-inorganic hybrid materials formed by the self-assembly of metal ions or clusters and organic ligands. MIP-207, a newly emerging titanium-based metal-organic framework (Ti-MOF) material, boasts large surface area, high porosity, abundant metal active sites, and diverse structures. Since only two of the three carboxyl groups in the 1,3,5-benzenetricarboxylic acid (BTC) ligand of MIP-207 participate in coordination, the remaining carboxylic acid does not participate in coordination and can be replaced with other functional groups. Therefore, MIP-207 can be modified by introducing different functional groups. Summary of the Invention

[0004] To address the shortcomings of the existing technology, the present invention provides a method for preparing a functional group-modified MIP-207 catalyst and its application. The present invention uses isopropyl titanate as a titanium source, an initial ligand 1,3,5-benzenetricarboxylic acid (BTC), and a functional group-modified ligand as an organic framework, and employs a reflux method to synthesize the novel functional group-modified titanium-based metal-organic framework material MIP-207.

[0005] The preparation method of the functional group-modified titanium-based metal-organic framework material MIP-207 comprises the following steps:

[0006] Acetic acid and acetic anhydride were added to a round-bottom flask and stirred thoroughly. Subsequently, isopropyl titanate was added to the mixed solution as a titanium source, followed by x mmol of a functional group-modified ligand and (10-x) mmol of an initial ligand, BTC. After sufficient stirring, the mixed solution was refluxed for reaction. After the reaction was complete, the solid powder in the mixed solution was centrifuged and finally the solid was washed, activated, and vacuum dried.

[0007] Furthermore, the amount of isopropyl titanate, functional group-modified ligand, initial ligand BTC, acetic acid and acetic anhydride is 6.75 mmol:x mmol:(10-x) mmol:25 mL:25 mL; wherein x is 2.5-5; that is, the functional group-modified ligand accounts for 25%-50% of the total ligand molar amount.

[0008] Furthermore, the reflux reaction temperature is 120° C., and the time is 10 to 14 hours.

[0009] Furthermore, the washing and activation operation is: washing with boiling acetone three times.

[0010] Furthermore, the vacuum drying temperature is 40-55°C.

[0011] The structural formula of the initial ligand 1,3,5-benzenetricarboxylic acid is:

[0012]

[0013] The functional group-modified ligand is 5-aminoisophthalic acid, 5-nitrobenzeneisophthalic acid, 5-hydroxyisophthalic acid or isophthalic acid; the structural formula is:

[0014]

[0015] -R: -NH2, -NO2, -OH or -H;

[0016] The functional group modified titanium-based metal organic framework material MIP-207 prepared by the present invention is used in catalytic oxidation fuel desulfurization. The specific application method is as follows:

[0017] A double-necked jacketed reaction flask was filled with a model oil and an extractant, followed by the addition of a functional group-modified titanium-based metal-organic framework (MIP-207) as a catalyst. The flask was then placed on a magnetic stirrer, a condenser was installed above the flask, and a water bath was introduced. The oxidant, H2O2, was added to the flask using a microinjection needle to initiate the reaction. The upper oil phase was removed at regular intervals throughout the reaction to determine the sulfur content. Four parallel experiments were conducted using this experimental setup to test the catalytic oxidative desulfurization performance of each functional group-modified MIP-207.

[0018] The ratio of the model oil, the extractant and the catalyst is 5 mL: 1-5 mL: 25-75 mg; the temperature of the water bath is 20-50° C.;

[0019] Preferably, the ratio of the model oil, the extractant and the catalyst is 5 mL: 1 mL: 50 mg; and the temperature of the water bath is 25°C.

[0020] Wherein, the oxygen-sulfur ratio of the reaction is 2 to 5, preferably 3;

[0021] The present invention has the following advantages:

[0022] This study synthesized a series of functionally group-modified MIP-207 catalysts using a reflux method. The MIP-207 structure contains abundant and independent Ti-Ox clusters, providing numerous catalytically active sites. Modification with various functional groups further enhances the catalyst's efficiency. Therefore, the functionally group-modified MIP-207 catalysts described herein exhibit highly efficient catalytic oxidation desulfurization of fuel oil.

[0023] The prepared functional group-modified MIP-207 catalyst has high catalytic performance. When used in catalytic oxidation desulfurization of fuel oil, it can achieve deep oxidative desulfurization of fuel oil (sulfur content less than 3ppm) at room temperature (25°C). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural perspective diagram of MIP-207.

[0025] Figure 2 This is the X-ray diffraction pattern of the functional group-modified MIP-207 catalyst.

[0026] Figure 3 This is the oxidative desulfurization activity diagram of the functional group-modified MIP-207 catalyst.

[0027] Figure 4 This is a diagram showing the recycling performance of the functional group-modified MIP-207 catalyst. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0029] The fuel types used in the following examples are:

[0030] (1) The model oil is prepared by dissolving dibenzothiophene (or 4-methyldibenzothiophene, 4,6-dimethyldibenzothiophene) in dodecane to prepare a model oil with a sulfur content of 200 ppm.

[0031] (2) In a jacketed reaction flask with magnetic stirring, a catalyst is added to the oil product, and an oxidant and an extractant are added, and an oxidative desulfurization reaction is carried out under magnetic stirring. During the reaction, the extractant phase and the oil phase are mixed. After the reaction, the extractant phase and the oil phase are allowed to stand and separate.

[0032] Gas chromatography (GC-FID) is used to detect the sulfide content in the oil and calculate the desulfurization rate:

[0033]

[0034] Comparative Example 1:

[0035] The preparation method of MIP-207 is as follows:

[0036] First, 25 mL of acetic acid (HAc) and 25 mL of acetic anhydride (Ac2O) were added to a 100 mL round-bottom flask, and the solution was stirred thoroughly using a magnetic stirrer. 10 mmol (2.10 g) of BTC and 6.75 mmol (2 mL) of isopropyl titanate (Ti(OiPr)4) were added to the solution and stirred for 30 min. The solution was then refluxed at 120 ° C for 12 h. After the reaction was completed, the reactor was cooled to room temperature and the solid was separated from the mixed solution using a centrifuge. The obtained solid was activated in boiling acetone 3 times, each time for 6 h. Finally, the solid was dried in a vacuum drying oven at 50 ° C for 6 h.

[0037] The content of sulfur compounds (dibenzothiophene) in the oil product was 200 ppm. 50 mg of MIP-207 catalyst, 5 mL of oil product, 1 mL of methanol (MeOH) extractant, and 9.6 μL of H2O2 were added to a double-necked jacketed reaction flask. The mixture was stirred with a magnetic stirrer and reacted at room temperature (25°C) for 90 minutes. After the extractant phase and the oil phase were allowed to stand and separate, the desulfurization rate reached 70.2%.

[0038] Example 1

[0039] The preparation method of MIP-207 with 25% functional group modification is as follows:

[0040] First, prepare four sets of 100 mL round-bottom flasks, add 25 mL of acetic acid (HAc) and 25 mL of acetic anhydride (Ac2O) into each round-bottom flask, and use a magnetic stirrer to fully stir the solution. Then, add 6.75 mmol (2 mL) of titanium source Ti(OiPr)4;

[0041] 7.5 mmol (1.57 g) of BTC was added to the above solutions, and 2.5 mmol of different functionalized ligands were added at a 25% molar ratio, namely: 0.42 g of isophthalic acid (IPA), 0.45 g of 5-aminoisophthalic acid (5-NH2-IPA), 0.46 g of 5-hydroxyisophthalic acid (5-OH-IPA), and 0.53 g of 5-nitroisophthalic acid (5-NO2-IPA). After stirring for 30 minutes, the solution was refluxed at 120°C for 12 hours. After the reaction was completed, the reactor was cooled to room temperature and the solid was separated from the mixed solution using a centrifuge. The obtained solid was activated in boiling acetone three times, each time for 6 hours. Finally, the solid was dried in a vacuum drying oven at 50°C for 6 hours. The obtained products were respectively recorded as MIP-207-(IPA) 25％ 、MIP-207-(5-NH2-IPA) 25％ 、MIP-207-(5-OH-IPA) 25％ 、MIP-207-(5-NO2-IPA) 25％ .

[0042] Example 2

[0043] According to the same synthesis method as Example 1, MIP-207 with 50% functional group modification can be synthesized.

[0044] First, prepare four sets of 100 mL round-bottom flasks, add 25 mL of acetic acid HAc and 25 mL of acetic anhydride Ac2O into each round-bottom flask, and use a magnetic stirrer to fully stir the solution. Then, add 6.75 mmol (2 mL) of titanium source Ti(OiPr)4;

[0045] 5.0 mmol (1.05 g) of BTC was added to the above solutions, and 5.0 mmol of different functionalized ligands were added at a 50% molar ratio, namely: 0.83 g of isophthalic acid (IPA), 0.91 g of 5-aminoisophthalic acid (5-NH2-IPA), 0.91 g of 5-hydroxyisophthalic acid (5-OH-IPA), and 1.01 g of 5-nitroisophthalic acid (5-NO2-IPA). After stirring for 30 minutes, the solution was refluxed at 120°C for 12 hours. After the reaction was completed, the reactor was cooled to room temperature and the solid was separated from the mixed solution using a centrifuge. The obtained solid was activated in boiling acetone three times, each time for 6 hours. Finally, the solid was dried in a vacuum drying oven at 50°C for 6 hours. The obtained products were respectively recorded as MIP-207-(IPA) 50％ 、MIP-207-(5-NH2-IPA) 50％ 、MIP-207-(5-OH-IPA) 50％、MIP-207-(5-NO2-IPA) 50％ .

[0046]

[0047] The application of the functional group-modified MIP-207 catalyst obtained in the present invention in the field of catalytic oxidation fuel desulfurization is as follows:

[0048] Application Example 4:

[0049] The content of sulfur compounds (dibenzothiophene) in the oil is 200ppm. 50mgMIP-207-(5-OH-IPA) is added to the double-necked jacketed reaction bottle. 50％ Catalyst, 5mL oil, 1mL MeOH extractant, 9.6μL H2O2, stirred with a magnetic stirrer, reacted at room temperature (25℃) for 90min, and the extractant phase and oil phase were separated after standing and stratification. The desulfurization rate reached 81.6%.

[0050] Application Example 5:

[0051] The content of sulfur compounds (dibenzothiophene) in the oil is 200ppm. 50mgMIP-207-(5-NO2-IPA) is added to the double-necked jacketed reaction bottle. 50％ Catalyst, 5mL oil, 1mL MeOH extractant, 9.6μL H2O2, stirred with a magnetic stirrer, reacted at room temperature (25℃) for 90min, and the extractant phase and oil phase were separated after standing and stratification. The desulfurization rate reached 86.5%.

[0052] Application Example 6:

[0053] The content of sulfur compounds (dibenzothiophene) in the oil is 200ppm. 50mg MIP-207 (IPA) is added to the double-necked jacketed reaction bottle. 50％ Catalyst, 5mL oil, 1mL MeOH extractant, 9.6μL H2O2, stirred with a magnetic stirrer, reacted at room temperature (25℃) for 90min, and the extractant phase and oil phase were separated after standing and stratification. The desulfurization rate reached 88.2%.

[0054] Application Example 7:

[0055] The sulfide (dibenzothiophene) content in the oil is 200 ppm. 50 mg of MIP-207-(5-NH2-IPA) is added to a double-necked jacketed reaction bottle. 50％ Catalyst, 5mL oil, 1mL MeOH, 9.6μL H2O2, stirred with a magnetic stirrer, reacted at room temperature (25℃) for 90min, and the extractant phase and the oil phase were separated after standing and stratification. The desulfurization rate reached 98.4%.

[0056] Figure 1 This is a perspective view of the structure of MIP-207. Figure 1 The structure of MIP-207 can be clearly seen in the figure: 1,3,5-benzenetricarboxylic acid is used as an organic ligand to connect Ti-O x Octahedral clusters form a typical metal-organic framework structure with a large number of cavities in the structure.

[0057] Figure 2 is the X-ray diffraction (XRD) pattern of functional group modified MIP-207. Figure 2 As can be seen from the figure, the diffraction pattern of the functional group-modified MIP-207 crystals is consistent with the original MIP-207 diffraction pattern, that is, the crystal structure of the functional group-modified MIP-207 has not changed significantly. In the spectrum, the diffraction peaks at 2θ = 5.16°, 10.32°, 11.54°, 14.62°, and 15.51° are attributed to the (110), (220), (130), (040), and (330) crystal planes, respectively.

[0058] Figure 3 Oxidative desulfurization activity diagram of functional group-modified MIP-207 catalyst. Figure 3 The results show that the catalytic oxidation desulfurization performance of MIP-207 catalysts modified with different functional groups is improved. Among them, MIP-207-(5-NH2-IPA) modified with amino functional groups is the best. 50％ It has the best catalytic oxidative desulfurization activity, which is attributed to the basic amino group in the catalyst. Specifically, the hydrogen atoms in the basic amino group can produce hydrogen bonds and acid-base interactions with the sulfur atoms of DBT. This makes MIP-207-(5-NH2-IPA) 50％ It has excellent catalytic oxidation desulfurization activity and can achieve ultra-deep oxidation desulfurization (98.4%) within 90 minutes at room temperature (25°C).

[0059] Figure 4 This is the recycling performance diagram of the functional group modified MIP-207 catalyst. Figure 4 It can be seen that MIP-207-(5-NH2-IPA) 50％ Under the condition of ensuring deep desulfurization of oil products, the catalyst can be recycled at least five times, has satisfactory recycling performance, and has certain industrial application value.

[0060] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. Application of functional group modified titanium-based metal organic framework material MIP-207 in catalytic oxidation fuel desulfurization, characterized in that: The preparation steps of the functional group modified titanium-based metal organic framework material MIP-207 are as follows: Acetic acid and acetic anhydride are added to a round-bottom flask and stirred thoroughly. Subsequently, isopropyl titanate is added to the mixed solution as a titanium source, followed by the functional group-modified ligand and the initial ligand 1,3,5-benzenetricarboxylic acid (BTC). After sufficient stirring, the mixed solution is refluxed for reaction. After the reaction is complete, the solid powder in the mixed solution is centrifuged and finally the solid is washed, activated, and vacuum dried. The functional group-modified ligand is 5-aminoisophthalic acid, 5-nitrobenzeneisophthalic acid, 5-hydroxyisophthalic acid or isophthalic acid; the structural formula is: -R: -NH2, -NO2, -OH or -H.

2. The use according to claim 1, characterized in that The steps are: Model oil and extractant were added to a double-necked jacketed reaction flask, and functional group-modified titanium-based metal-organic framework material MIP-207 was added as a catalyst. The flask was placed on a magnetic stirrer, a condenser was installed above the reaction flask, and the reaction flask was placed in a water bath. The oxidant H2O2 was added to the reaction flask using a microinjection needle to start the reaction. During the reaction, the upper oil phase was taken out at the same time intervals to detect the sulfur content in the oil.

3. The use according to claim 2, characterized in that The dosage ratio of the model oil, the extractant and the catalyst is 5 mL: 1-5 mL: 25-75 mg; the temperature of the water bath is 20-50° C.; and the oxygen-sulfur ratio of the reaction is 2-5.

4. The use according to claim 3, characterized in that The dosage ratio of model oil, extractant and catalyst is 5 mL:1 mL:50 mg; the temperature of the water bath is 25°C; and the oxygen-sulfur ratio of the reaction is 3.

5. The use according to claim 1, characterized in that The amount of isopropyl titanate, the functional group-modified ligand, the initial ligand 1,3,5-benzenetricarboxylic acid (BTC), acetic acid, and acetic anhydride is 6.75 mmol:x mmol:(10-x) mmol:25 mL:25 mL; wherein x is 2.5 to 5; i.e., the functional group-modified ligand accounts for 25% to 50% of the total ligand molar amount; The reflux reaction temperature is 120°C and the time is 10 to 14 hours; The operation of washing activation is as follows: washing three times with boiling acetone; The vacuum drying temperature is 40-55°C.

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