Adsorption desulfurization catalyst and preparation method thereof

Abstract

The present invention relates to the field of catalyst technology, and in particular to a kind of adsorption desulfurization catalyst and its preparation method. The catalyst is composited with modified graphene and montmorillonite as a carrier, and after molecular modification of graphene oxide using chloropropyltriethoxysilane and 2-dimethylaminoethylphosphoric acid, it is efficiently composited with montmorillonite K10, then loaded with zinc and magnesium metals, and calcined under nitrogen protection to obtain. The method optimizes the synergistic structure of graphene and montmorillonite, significantly improves the specific surface area and pore structure, enhances the dispersion and stable binding ability of metal ions, and simultaneously introduces functional molecules to improve the adsorption activity of the catalyst for aromatic sulfides, and suppresses the loss of active components. The prepared catalyst shows excellent desulfurization efficiency, cyclic stability and durability, adapts to the needs of green and low-carbon chemical industry, and has good industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to an adsorption desulfurization catalyst and a preparation method thereof. Background Art

[0002] With increasingly stringent global environmental regulations and the continuous reduction of sulfur content limits in petroleum products, particularly fuel oil, deep desulfurization technology has become a key research area in the petrochemical industry. While traditional hydrodesulfurization processes are widely used, they suffer from low desulfurization efficiency for fuel oils containing aromatic sulfides, harsh reaction conditions, high energy consumption, and significant equipment investment. Therefore, the development of new, efficient, economical, and environmentally friendly desulfurization technologies is of great significance.

[0003] Oxidative adsorption desulfurization technology has attracted widespread attention due to its mild reaction conditions and high selectivity for aromatic sulfides. This technology uses an oxidant to convert sulfur-containing compounds into their corresponding sulfones or sulfoxides, which are then selectively removed by adsorbent. In this process, catalyst performance directly impacts desulfurization efficiency and economic viability. Currently, commonly used oxidative adsorption desulfurization catalysts include molecular sieves, activated carbon, and metal oxides. However, these materials often suffer from issues such as insufficient specific surface area, uneven distribution of active sites, and rapid degradation of recyclable performance.

[0004] Montmorillonite is widely used in catalysis and adsorption due to its unique layered structure, abundant surface functional groups, and excellent ion exchange capacity. However, single montmorillonite is prone to layered structure collapse during recycling, resulting in a reduction in specific surface area and shielding of active sites, which in turn affects catalytic desulfurization efficiency. On the other hand, graphene and its derivatives have become a hot topic in composite material research due to their unique two-dimensional structure and excellent physical and chemical properties. In particular, the rich oxygen-containing functional groups on the surface of graphene oxide not only provide abundant modification sites but also enhance the adsorption capacity of aromatic sulfides through π-π interactions.

[0005] Composites of graphene and montmorillonite can unleash their synergistic effects. However, in existing technologies, simple physical mixing of graphene and montmorillonite makes it difficult to form a stable composite structure and lacks sufficient active sites for the fixation of metal active components. Furthermore, during the metal oxide loading process, the metal components are prone to agglomeration or loss due to the lack of an effective coordination structure, making it difficult to form highly dispersed active centers, which in turn affects catalytic activity and cyclic stability. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide an adsorptive desulfurization catalyst and a preparation method thereof, so as to provide a catalyst having high stability and high adsorptive desulfurization efficiency which is a composite of graphene and montmorillonite.

[0007] Based on the above purpose, the present invention provides a method for preparing an adsorption desulfurization catalyst, comprising the following steps:

[0008] (1) Graphene oxide is modified with chloropropyltriethoxysilane to obtain chlorinated graphene oxide;

[0009] (2) Modified graphene is obtained by quaternization reaction of chlorinated graphene oxide and 2-dimethylaminoethyl phosphoric acid;

[0010] (3) Adding the modified graphene and montmorillonite K10 into deionized water, ultrasonicating for 20-40 min, stirring for 1.5-2.5 h, centrifuging, washing, and drying to obtain a modified graphene-montmorillonite composite;

[0011] (4) Add zinc nitrate and magnesium nitrate to deionized water and stir at room temperature for 0.5-1.5 hours to obtain an impregnation solution;

[0012] (5) Immersing the modified graphene-montmorillonite composite in the impregnation solution, heating to 35-45°C, stirring for 5-7 hours, centrifuging, and drying to obtain a modified graphene-montmorillonite composite loaded with zinc and magnesium;

[0013] (6) The modified graphene-montmorillonite composite loaded with zinc and magnesium was calcined in a nitrogen atmosphere and cooled in the furnace to obtain an adsorption desulfurization catalyst.

[0014] In the step (1), the weight ratio of chloropropyltriethoxysilane to graphene oxide is 10:0.5-1.5.

[0015] In the step (1), the weight ratio of the chlorinated graphene oxide to 2-dimethylaminoethyl phosphoric acid is 10:0.3-0.8.

[0016] The weight ratio of modified graphene to montmorillonite K10 in step (3) is 5:15-25.

[0017] The stirring speed in step (3) is 1000-2000 rpm.

[0018] In the step (4), the weight ratio of zinc nitrate, magnesium nitrate and deionized water is 5-10:1.5-3:40-60.

[0019] In the step (5), the weight ratio of the modified graphene-montmorillonite composite to the impregnation solution is 20-30:40-60.

[0020] The calcination temperature in step (6) is 330-370° C. and the calcination time is 3-4 hours.

[0021] The adsorption desulfurization catalyst provided by the present invention has achieved innovative breakthroughs in structural design and modification methods, and has the following beneficial effects:

[0022] The present invention significantly improves the structure and performance of the catalyst by molecular modification and structural optimization of graphene materials and efficiently compounding them with inorganic layered montmorillonite. The introduction of modified graphene plays a strong constructive role in the composite material, forming a stable and orderly synergistic system between the two-dimensional lamellar structure and the montmorillonite layer. This structural design not only provides favorable conditions for the high dispersion of metal species, but also significantly inhibits the agglomeration and structural collapse of the composite during the desulfurization cycle, thereby maintaining the high specific surface area and rich pore structure of the material. This multi-level pore structure creates a convenient mass transfer environment for the diffusion and adsorption of reactant molecules, greatly improving the exposure and accessibility of catalytic active sites.

[0023] In addition, the present invention achieves orderly grafting of functional groups through the introduction of functional molecules. The presence of phosphate groups not only enhances the coordination ability for metal ions and promotes the uniform adsorption and binding of metal precursors, but also effectively prevents the loss of metal active components during use through a stable anchoring effect, thereby ensuring the efficient and long-lasting operation of the catalyst. At the same time, the quaternary ammonium groups on the surface of the material further bring about stable doping of nitrogen elements during the subsequent heat treatment process, optimizing the surface electronic state of the carrier, thereby enhancing the adsorption activity of the catalyst for the target sulfide molecules. This series of innovative designs at the molecular level greatly optimizes the synergistic enhancement mechanism of the catalyst in the desulfurization reaction.

[0024] The catalyst material of the present invention not only achieves a high initial desulfurization capacity but also exhibits excellent cyclic stability and durability. During repeated use, the material structure is not easily collapsed, the loss of active components is controlled, and the catalytic performance remains stable. Overall, the catalyst of the present invention has significant advantages in structural design, synergistic mechanism, and comprehensive performance, meeting the needs of green and low-carbon development and possessing broad practical application prospects and industrial promotion value. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0026] The graphene oxide in the specific embodiment of the present invention was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with the item number G476412, and the montmorillonite K10 was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with the item number M758183.

[0027] Example 1:

[0028] (1) Add 10 g of graphene oxide to 20 g of deionized water and 60 g of anhydrous ethanol, ultrasonicate for 20 min, then add 0.5 g of chloropropyltriethoxysilane, heat to 50 ° C, stir and react for 5 h, centrifuge, wash, and dry to obtain chlorided graphene oxide;

[0029] (2) 10 g of chlorinated graphene oxide and 0.3 g of 2-dimethylaminoethyl phosphoric acid were added to 80 g of tetrahydrofuran, heated to 48 ° C under a nitrogen atmosphere, stirred and reacted for 40 h, centrifuged, washed, and dried to obtain modified graphene;

[0030] (3) 5 g of modified graphene and 15 g of montmorillonite K10 were added to deionized water, ultrasonicated for 20 min, stirred at 1000 rpm for 1.5 h, centrifuged, washed, and dried to obtain a modified graphene-montmorillonite composite;

[0031] (4) Add 5 g of zinc nitrate and 1.5 g of magnesium nitrate to 40 g of deionized water and stir at room temperature for 0.5 h to obtain an impregnation solution;

[0032] (5) Immerse 20 g of the modified graphene-montmorillonite composite in 40 g of the impregnation solution, heat to 35 ° C, stir for 5 h, centrifuge, and dry to obtain a modified graphene-montmorillonite composite loaded with zinc and magnesium;

[0033] (6) Under nitrogen atmosphere, the modified graphene-montmorillonite composite loaded with zinc and magnesium was calcined at 330 °C for 3 h and then cooled in the furnace to obtain an adsorption desulfurization catalyst.

[0034] Example 2:

[0035] (1) 10 g of graphene oxide was added to 30 g of deionized water and 70 g of anhydrous ethanol, and ultrasonicated for 30 min. Then 1 g of chloropropyltriethoxysilane was added, and the temperature was raised to 55 ° C. The mixture was stirred for 6 h, centrifuged, washed, and dried to obtain chlorinated graphene oxide.

[0036] (2) Add 10 g of chlorinated graphene oxide and 0.5 g of 2-dimethylaminoethyl phosphoric acid to 100 g of tetrahydrofuran, raise the temperature to 50 ° C under a nitrogen atmosphere, stir and react for 48 hours, centrifuge, wash, and dry to obtain modified graphene;

[0037] (3) 5 g of modified graphene and 20 g of montmorillonite K10 were added to deionized water, ultrasonicated for 30 min, stirred at 1500 rpm for 2 h, centrifuged, washed, and dried to obtain a modified graphene-montmorillonite composite;

[0038] (4) Add 7.4 g of zinc nitrate and 2.2 g of magnesium nitrate to 50 g of deionized water and stir at room temperature for 1 h to obtain an impregnation solution;

[0039] (5) Immerse 25 g of the modified graphene-montmorillonite composite in 50 g of the impregnation solution, heat to 40 ° C, stir for 6 h, centrifuge, and dry to obtain a modified graphene-montmorillonite composite loaded with zinc and magnesium;

[0040] (6) Under nitrogen atmosphere, the modified graphene-montmorillonite composite loaded with zinc and magnesium was calcined at 350 °C for 3.5 h and then cooled in the furnace to obtain an adsorption desulfurization catalyst.

[0041] Example 3:

[0042] (1) 10 g of graphene oxide was added to 40 g of deionized water and 80 g of anhydrous ethanol, and ultrasonically treated for 40 min. Then, 1.5 g of chloropropyltriethoxysilane was added, and the temperature was raised to 60 ° C. The mixture was stirred for 7 h, centrifuged, washed, and dried to obtain chlorinated graphene oxide;

[0043] (2) Add 10 g of chlorinated graphene oxide and 0.8 g of 2-dimethylaminoethyl phosphoric acid to 120 g of tetrahydrofuran, raise the temperature to 52 ° C under a nitrogen atmosphere, stir and react for 60 h, centrifuge, wash, and dry to obtain modified graphene;

[0044] (3) 5 g of modified graphene and 25 g of montmorillonite K10 were added to deionized water, ultrasonicated for 40 min, stirred at 2000 rpm for 2.5 h, centrifuged, washed, and dried to obtain a modified graphene-montmorillonite composite;

[0045] (4) Add 10 g of zinc nitrate and 3 g of magnesium nitrate to 60 g of deionized water and stir at room temperature for 1.5 h to obtain an impregnation solution;

[0046] (5) Immerse 30 g of the modified graphene-montmorillonite composite in 60 g of the impregnation solution, heat to 45 ° C, stir for 7 h, centrifuge, and dry to obtain a modified graphene-montmorillonite composite loaded with zinc and magnesium;

[0047] (6) Under nitrogen atmosphere, the modified graphene-montmorillonite composite loaded with zinc and magnesium was calcined at 370 °C for 4 h and then cooled in the furnace to obtain an adsorption desulfurization catalyst.

[0048] Comparative Example 1:

[0049] The difference between Comparative Example 1 and Example 2 is that the modified graphene in step (3) is replaced by graphene oxide;

[0050] Comparative Example 2:

[0051] The difference between Comparative Example 2 and Example 2 is that the 2-dimethylaminoethyl phosphoric acid in step (2) is replaced by 2-dimethylaminoethyl acetate;

[0052] Comparative Example 3:

[0053] The difference between Comparative Example 3 and Example 2 is that the 2-dimethylaminoethyl phosphoric acid in step (2) is replaced by 2-aminoethylphosphonic acid;

[0054] Comparative Example 4:

[0055] The difference between Comparative Example 3 and Example 2 is that the modified graphene-montmorillonite composite in step (5) is replaced by montmorillonite K10;

[0056] Performance testing:

[0057] Specific surface area: tested by BET nitrogen adsorption-desorption instrument.

[0058] Preparation of simulated oil: Dissolve 0.432 g of dibenzothiophene in 250 mL of n-octane to obtain a simulated oil with a dibenzothiophene concentration of 300 ppm. Simulated oils with dibenzothiophene concentrations of 100 ppm, 200 ppm, 400 ppm, and 500 ppm were prepared using the same method.

[0059] The oxidative adsorption desulfurization process was carried out in a 250 mL flask. 10 mL of simulated oil (300 ppm) was added, followed by 100 mg of a 30 wt% aqueous hydrogen peroxide solution and 30 mg of the catalyst. The desulfurization reaction was carried out at 60°C for 3 h. The reaction solution was then centrifuged, and the supernatant, representing the clean oil, was analyzed using a microcoulometric detector (WK-2D). After the reaction, the catalyst was separated from the simulated oil and then mixed with acetonitrile in a 1:5 weight ratio. After sonication for 30 min, the mixture was centrifuged and dried for use in a cyclic test. The results are shown in Table 1.

[0060] Table 1 Performance test results

[0061]

[0062] Data Analysis:

[0063] As can be seen from the data of Examples 1-3 in Table 1, the adsorption desulfurization catalyst prepared by the present invention exhibits excellent performance characteristics, with a high specific surface area and excellent initial desulfurization efficiency. Furthermore, the catalyst maintained a desulfurization efficiency of 93.8% after 10 cycles, demonstrating its excellent stability and durability.

[0064] The data from Example 2 and Comparative Example 1 in Table 1 show that the pore structure of the catalyst is significantly reduced when unmodified graphene oxide is used. Modified graphene may improve performance through the following pathways: 1) Chemical bonding with the montmorillonite layered structure strengthens the support skeleton and inhibits structural collapse during cycling; 2) The strong coordination ability of the phosphate groups promotes the permeation adsorption of metal precursor solutions, forming a finer metal oxide dispersion; 3) The nitrogen doping effect produced by the quaternary ammonium groups during calcination may optimize the electronic state of the support surface and enhance the chemical adsorption capacity of sulfide molecules; 4) The quaternary ammonium groups can strip the montmorillonite interlayer structure during mixing with the montmorillonite, promoting the formation of a new composite structure between graphene and montmorillonite.

[0065] The data from Example 2 and Comparative Example 2 in Table 1 show that the catalyst's desulfurization efficiency and cycle retention rate decreased simultaneously after the phosphate groups were replaced by acetate groups. It is speculated that the unique molecular structure of dimethylaminoethylphosphoric acid may have the following effects: 1) The bidentate coordination mode of the phosphate groups forms a more stable chelate structure with metal ions; and 2) the introduction of phosphorus may enhance the interfacial bonding strength between montmorillonite and metal oxides by forming PO-Mg bonds. This synergistic effect at the molecular level effectively suppresses the loss of active components during recycling.

[0066] As can be seen from the data of Example 2 and Comparative Example 3 in Table 1, the catalyst modified with 2-dimethylaminoethylphosphonic acid has a higher specific surface area and desulfurization efficiency than the catalyst modified with 2-aminoethylphosphonic acid. This may be because 2-aminoethylphosphonic acid cannot form quaternary ammonium groups after grafting onto the graphene surface, thus lacking the quaternary ammonium group's strengthening effect on the catalyst.

[0067] From the data of Example 2 and Comparative Example 4 in Table 1, it can be seen that the catalyst using the modified graphene-montmorillonite composite as a support exhibits significantly higher specific surface area and desulfurization efficiency than the catalyst using montmorillonite K10 directly as a support. This may be because the intercalation recombination effect of the modified graphene effectively increases the specific surface area of ​​the material, providing more active sites for metal ion loading. The π-electron structure of the modified graphene may enhance the adsorption capacity of aromatic ring sulfides, while the surface functional groups provide more catalytic active sites. During the calcination process, the presence of the modified graphene may promote the formation and dispersion of metal oxides, enhancing the thermal stability and recyclability of the catalyst.

[0068] The discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A method for preparing an adsorption desulfurization catalyst, characterized in that: The following steps are involved: (1) Graphene oxide is modified with chloropropyltriethoxysilane to obtain chlorinated graphene oxide; (2) Modified graphene is obtained by quaternization reaction of chlorinated graphene oxide and 2-dimethylaminoethyl phosphoric acid; (3) Adding the modified graphene and montmorillonite K10 into deionized water, ultrasonicating for 20-40 min, stirring for 1.5-2.5 h, centrifuging, washing, and drying to obtain a modified graphene-montmorillonite composite; (4) Add zinc nitrate and magnesium nitrate to deionized water and stir at room temperature for 0.5-1.5 hours to obtain an impregnation solution; (5) Immersing the modified graphene-montmorillonite composite in the impregnation solution, heating to 35-45°C, stirring for 5-7 hours, centrifuging, and drying to obtain a modified graphene-montmorillonite composite loaded with zinc and magnesium; (6) The modified graphene-montmorillonite composite loaded with zinc and magnesium was calcined in a nitrogen atmosphere and cooled in the furnace to obtain an adsorption desulfurization catalyst.

2. The method for preparing an adsorption desulfurization catalyst according to claim 1, wherein: In the step (1), the weight ratio of chloropropyltriethoxysilane to graphene oxide is 10:0.5-1.

5.

3. The method for preparing an adsorption desulfurization catalyst according to claim 1, wherein: In the step (1), the weight ratio of the chlorinated graphene oxide to 2-dimethylaminoethyl phosphoric acid is 10:0.3-0.

8.

4. The method for preparing an adsorption desulfurization catalyst according to claim 1, wherein: The weight ratio of modified graphene to montmorillonite K10 in step (3) is 5:15-25.

5. The method for preparing an adsorptive desulfurization catalyst according to claim 1, wherein: The stirring speed in step (3) is 1000-2000 rpm.

6. The method for preparing an adsorption desulfurization catalyst according to claim 1, wherein: In the step (4), the weight ratio of zinc nitrate, magnesium nitrate and deionized water is 5-10:1.5-3:40-60.

7. The method for preparing an adsorptive desulfurization catalyst according to claim 1, wherein: In the step (5), the weight ratio of the modified graphene-montmorillonite composite to the impregnation solution is 20-30:40-60.

8. The method for preparing an adsorptive desulfurization catalyst according to claim 1, wherein: The calcination temperature in step (6) is 330-370° C. and the calcination time is 3-4 hours.

9. An adsorption desulfurization catalyst, characterized in that: The desulfurization catalyst is obtained by the preparation method of the adsorption desulfurization catalyst according to any one of claims 1 to 8.

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