Porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated monatomic metal as well as preparation method and application of porous graphene / regenerated cellulose composite catalytic material
Through the porous graphene/regenerated cellulose composite catalytic material supported by N/O co-coordinated single-atom metal, the problem of insufficient performance of non-precious metal catalysts in fixed bed catalytic systems is solved, efficient continuous flow catalysis is achieved, and cost is reduced.
Patent Information
- Application Number
- CN202510554911.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-29
- Publication Date
- 2025-08-05
AI Technical Summary
In the existing fixed-bed catalytic system, the catalytic performance of non-precious metal single-atom catalysts is insufficient, and the mass transfer and catalytic efficiency are low, making it difficult to meet the needs of continuous flow operations. The cost of precious metal catalysts is high, which limits its large-scale application.
Using a porous graphene/regenerated cellulose composite catalytic material that supports N/O co-coordinated single atom metal, a porous fiber skeleton is formed by winding cellulose fibers, combining graphene sheets and N/O co-coordinated single atom metal. The preparation method includes adding graphene oxide and cellulose to the viscous solution, and creating pores through hydrothermal reaction and etching to achieve uniform loading of metal single atoms.
Under continuous flow operation, excellent flowability and catalytic performance are shown, which improves catalytic efficiency and reduces costs, making it suitable for promotion and application.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalytic materials, and in particular relates to a porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metals, and a preparation method and application thereof. Background Art
[0002] Fixed-bed systems are typical flow chemistry catalytic devices. Traditionally, catalysts are packed in either block or powder form. Block catalysts create a loose packing structure, which can lead to low catalytic efficiency. Powdered catalysts, on the other hand, tend to create an overly dense packing structure, reducing mass transfer and catalytic efficiency. Further designing catalytic materials with high activity, excellent durability, and low flow resistance remains both significant and challenging.
[0003] By using high-performance single-atom catalysts as active fillers and integrating them with flow chemistry technology, a fixed-bed continuous flow catalytic system can be constructed, which is conducive to promoting high metal utilization and realizing the continuity and automation of the catalytic process. However, the existing catalytically active components are usually nano-sized precious metals, which are expensive and limit their large-scale use. In addition, due to their own properties, the performance of non-precious metal catalysts is significantly different from that of precious metals; in a fixed-bed system, when the higher flow rate shortens the contact time between the reactants and the catalyst, its catalytic efficiency is often difficult to meet the requirements. Therefore, fixed-bed research based on non-precious metal single-atom catalysts has not yet been widely carried out. To break through this bottleneck, it is necessary to first improve its catalytic performance.
[0004] Theoretically, the maximum atomic utilization can be achieved when the metal exists in the form of a single atom. However, the surface energy of the individual metals in the single-atom catalyst is extremely large, which makes them easy to agglomerate into nanoparticles, thereby reducing their atomic utilization. The stability of single metal atoms can be greatly improved by using heteroatoms (such as N, O, S, P, etc.) to coordinate with metal atoms. In recent years, a large number of research results have shown that the coordination of different atoms with metal single atoms can further regulate the chemical environment of the metal active site and improve the activity and selectivity of single-atom catalysts. However, there are still problems such as the limited amount of heteroatom doping and the limited coordination anchoring effect of multiple heteroatoms on the metal. Summary of the Invention
[0005] The main purpose of the present invention is to address the problems and shortcomings of the existing technology and provide a porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metals. When applied to a fixed bed system, it can exhibit excellent fluidity and catalytic performance under continuous flow operation.
[0006] To achieve the above object, the technical solution adopted by the present invention is:
[0007] A porous graphene / cellulose composite catalytic material loaded with N / O co-coordinated single-atom metal comprises a porous fiber skeleton formed by winding cellulose fibers, and graphene sheets and N / O co-coordinated single-atom metal composited therein, wherein the single-atom metal is one or more of Cu, Bi, Ru, Zn, Mo, Co, Ni, and Fe.
[0008] Furthermore, the composite catalytic material is in a fibrous shape, and its aspect ratio is 160-1500:1.
[0009] Furthermore, the diameter of the porous fiber skeleton is 0.2-0.5 mm; the diameter of a single cellulose fiber is 3-20 μm.
[0010] In the above solution, the pore size of the composite catalytic material is 10-100 nm.
[0011] Furthermore, in the composite catalytic material, the N element content reaches 1.0-8.9at%, the O element content reaches 8.5-27.75at%, and the single-atom metal content reaches 0.2-7.0at%.
[0012] The present invention also provides a method for preparing the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal, comprising the following steps:
[0013] 1) adding graphene oxide to a cellulose solution under stirring to obtain a viscous solution; then extruding the solution into a coagulation bath and solidifying it to prepare a GO / RCWP composite fiber;
[0014] 2) mixing hydrogen peroxide, a nitrogen source, and a non-precious metal salt solution uniformly, adding GO / RCWP composite fibers to the resulting mixture, sealing, performing a hydrothermal reaction, washing, and drying to obtain the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal.
[0015] In the above solution, the cellulose introduced into the cellulose solution is derived from plant fibers or regenerated fibers (derived from waste paper fiber products).
[0016] In the above scheme, the concentration of cellulose in the cellulose solution is 40-80 mg / mL.
[0017] In the above solution, the solvent used in the cellulose solution is an alkaline aqueous solution of urea.
[0018] Furthermore, in the cellulose solution, the concentration of urea is 0.23-0.25 mg / mL, and the concentration of alkali is 0.11-0.13 mg / mL.
[0019] Furthermore, the alkali used in the alkaline aqueous solution of urea is NaOH.
[0020] In the above scheme, the graphene oxide is added in the form of an aqueous solution, wherein the concentration of the graphene oxide aqueous solution is 8.3-11.0 mg / mL.
[0021] In the above scheme, the mass ratio of the introduced graphene oxide to cellulose is 1:6.75-8.00.
[0022] In the above solution, the GO / RCWP composite fiber has a diameter of 0.2-0.5 mm and a length of 8-30 cm.
[0023] In the above scheme, the coagulation bath condition can be diluted hydrochloric acid or diluted nitric acid, etc.; the concentration thereof is 0.12-0.36 mol / L.
[0024] In the above scheme, the nitrogen source is ammonia water or urea.
[0025] Furthermore, the concentration of the ammonia water is 28-30 wt.%.
[0026] In the above scheme, the non-precious metal is one or more of Cu, Bi, Ru, Zn, Mo, Co, Ni, Fe, etc.
[0027] In the above solution, the non-noble metal salt is a water-soluble salt.
[0028] Furthermore, the non-noble metal salt can be selected from one or more of copper chloride, copper nitrate, bismuth nitrate, ruthenium chloride, zinc chloride, ammonium molybdate, sodium molybdate, cobalt nitrate, nickel sulfate, ferric nitrate, ferric chloride, etc.
[0029] In the above scheme, the mass ratio of non-noble metal salt to graphene oxide, hydrogen peroxide, and nitrogen source is 1:(3.76-4.71):(0.62-1.71):(52.71-105.41).
[0030] In the above scheme, the concentration of the graphene oxide solution is 8.2-11.0 mg / mL, and the most preferred concentration of graphene is 9.0-11.0 mg / mL.
[0031] Furthermore, the hydrogen peroxide is introduced in the form of an aqueous solution with a concentration of 0.3-30 wt.%.
[0032] In the above scheme, the temperature of the hydrothermal reaction is 170-180° C., and the time is 6.5-8.5 h.
[0033] The porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single-atom metal described in the above scheme can be used to catalyze the reduction reaction of aromatic nitro compounds and the degradation reaction of bisphenol A.
[0034] Furthermore, the aromatic nitro compound can be selected from
[0035] Furthermore, the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal is applied in a fixed bed system under continuous flow operation.
[0036] Furthermore, the packing density of the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal is 0.288-0.432 g / cm 3 , at a flow rate of 4-100mL / min, efficient catalysis of the reactants can be achieved.
[0037] Furthermore, the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal has a catalytic reduction rate of nitroaromatic compounds of up to 3.2×10 -2 mmol / (mg·min); when applied in a fixed bed system, the selectivity reaches 100% and the yield reaches over 93%.
[0038] Furthermore, the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal has a catalytic degradation rate of bisphenol A as high as 4.10×10 -4 mmol / (mg·min).
[0039] Compared with the prior art, the present invention has the following beneficial effects:
[0040] 1) The composite catalytic material of the present invention comprises a fiber skeleton formed by winding cellulose fibers and a composite of graphene sheets and N / O co-coordinated single-atom metals therein; the fibrous catalyst exhibits a higher flow rate and a higher treatment rate while maintaining stability;
[0041] 2) The present invention first prepares a graphene / fiber catalyst precursor in a viscous solution, regulates the degree of cellulose coating on the graphene and the aspect ratio of the resulting composite material, and then introduces hydrogen peroxide, a nitrogen source, and a non-precious metal salt for a hydrothermal reaction to promote the exposure of more graphene. Etching, pore formation, and other methods are used to provide more space for the loading of metal single atoms and effectively inhibit the formation of metal nanoparticles, thereby achieving uniform loading of metal single atoms and N / O co-coordination. The resulting composite catalytic fiber has abundant active sites and can exhibit excellent catalytic efficiency when applied to a fixed bed system under continuous flow catalysis.
[0042] 3) The preparation method of the present invention is simple, reproducible, and environmentally friendly. The non-precious metal salt used is low in cost and suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] Figure 1This is a flow chart for the preparation of porous graphene-regenerated cellulose composite catalytic fibers loaded with N / O co-coordinated single-atom metals in the present invention.
[0044] Figure 2 Comparison of transmission electron micrographs of the porous graphene-regenerated cellulose composite catalytic fiber loaded with N / O co-coordinated single-atom copper prepared in Example 1 and the nitrogen-doped porous graphene composite catalyst prepared in Comparative Example 1. Figure a is a scanning electron micrograph and photograph of NHG-RCWP, bc are scanning electron micrographs of Cu1 / NHG-RCWP, and df are transmission electron micrographs of Cu1 / NHG-RCWP.
[0045] Figure 3 This is a spherical aberration corrected scanning transmission electron microscope image of the composite catalytic fiber prepared in Example 1.
[0046] Figure 4 This is a scan of the energy spectrum of the composite catalytic fiber prepared in Example 1.
[0047] Figure 5 This is the X-ray photoelectron spectrum of the composite catalytic fiber prepared in Example 1.
[0048] Figure 6 This is the X-ray absorption near-edge spectrum of the K edge of the composite catalytic fiber prepared in Example 1.
[0049] Figure 7 This is the K-edge extended Fourier transform spectrum X-ray absorption fine structure spectrum of the composite catalytic fiber prepared in Example 1.
[0050] Figure 8 This is the spherical aberration corrected scanning transmission electron micrograph of the double single-atom composite catalytic fiber prepared in Example 5.
[0051] Figure 9 a and b are actual pictures of the Cu1 / NHG-RCWP composite catalytic fiber obtained in Example 1 before and after the continuous flow reduction of 4-NP in the fixed-bed catalytic system, c is the UV / visible absorption spectrum before and after the reduction of 4-NP, d is the cyclic stability diagram of the Cu1 / NHG-RCWP composite catalytic fiber, e and f are actual pictures of the Cu1 / NHG-RCWP composite catalytic fiber obtained in Example 1 before and after the continuous flow heating degradation of BPA in the fixed-bed catalytic system.
[0052] Figure 10 Performance diagram of Cu1 / NHG-RCWP composite catalytic fiber for catalytic degradation of BPA. DETAILED DESCRIPTION
[0053] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0054] In the following examples, graphene oxide with a sheet diameter of 10 nm-40 μm was prepared according to a modified Hummers method [WS Hummers Jr, RE Offeman, Preparation of graphic oxide. Journal of the American Chemical Society, 1958, 208, 1334-1339].
[0055] In the following examples, the regenerated cellulose used was obtained from waste paper.
[0056] Example 1
[0057] A porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single-atom copper (Cu1 / NHG-RCWP) is prepared by the following steps:
[0058] First, 300 mg of regenerated cellulose was dissolved in 5 mL of a urea-NaOH-H2O mixed solution (the mass ratio of urea, NaOH, and H2O was 1:2:8) under stirring conditions; 40 mg of a graphene oxide dispersion (concentration of 9.99 mg / mL) was added, and stirring was continued in an ice bath until a black viscous colloid was formed; the resulting viscous colloid was then squeezed into a dilute hydrochloric acid solution (concentration of 0.12 mol / L; the same below) through a syringe (needle tip diameter of 1.0 mm, the same below) for solidification, washed with water until neutral, and dried to obtain GO / RCWP fibers (aspect ratio of 200-600:1) for later use;
[0059] The obtained GO / RCWP fiber, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.33 wt.% hydrogen peroxide solution and 0.5 mL of 21.25 mg / mL copper chloride solution were added to a 100 mL polytetrafluoroethylene reactor liner, stirred evenly, and then hydrothermally reacted at 180°C for 8 h. After the reaction, the reaction system was cooled to room temperature to obtain a porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic copper (Cu1-N2O2).
[0060] Table 1 Data fitted based on the backscattering paths of CuN and Cu2O
[0061]
[0062] R: bond distance; σ2 :Debye-Waller factor; S0 2 : instrument error; R factor: fitting matching degree
[0063] The SEM / TEM images of the porous graphene-regenerated cellulose composite catalytic fibers loaded with N / O co-coordinated single-atom copper prepared in this example are shown in FIG. Figure 2 . Figure 2 Scanning electron microscopy images reveal a single extruded, bare RCWP ultrafine fiber skeleton (approximately 200 μm in diameter) composed of multiple regenerated cellulose fibers (approximately 10 μm in diameter), randomly intertwined to form a loose structure. Transmission electron microscopy images also reveal the presence of ultrathin graphene sheets, confirming the successful composite of cellulose and NHG. Furthermore, testing revealed a pore size distribution within the 10-100 nm range for the resulting composite.
[0064] Figure 3 The white bright spots in the spherical aberration-corrected scanning transmission electron microscope represent single copper atoms, and it can be seen that the copper atoms are evenly distributed on the nitrogen-doped graphene NHG sheet.
[0065] Figure 4 The energy spectrum can further confirm the uniform element (C, O, N and Cu) distribution in the active composite material Cu1-NHG in the scheme described in Example 1.
[0066] Figure 5 The X-ray photoelectron spectrum of the porous graphene-regenerated cellulose composite catalytic fiber loaded with N / O co-coordinated single atomic copper obtained in this example shows that the N element content in the obtained composite catalytic fiber is 1.05at%, the O element content is 27.73at%; and the single atomic copper content is 0.24at%. Figure 6 This is the synchrotron radiation analysis diagram of the obtained catalytic material. The results show that the oxidation state of copper atoms in Cu1 / NHG-RCWP is between 0 and +2, and the coordination structure of Cu single atoms is Cu1-N2O2.
[0067] Figure 7 K-edge extended Fourier transform spectroscopy X-ray absorption fine structure spectrum, there is no Cu-Cu bond in the spectrum, and analysis shows that Cu exists as a single atom in the catalyst prepared in Example 1.
[0068] Example 2
[0069] A porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single-atom copper is prepared by the following steps:
[0070] First, 290 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (the mass ratio of urea, NaOH, and H2O was 1:2:8) under stirring conditions, and then 40 mg of a 9.99 mg / mL graphene oxide dispersion was added. The mixture was then placed in an ice bath to obtain a black viscous colloid. The obtained viscous colloid was then squeezed into a dilute hydrochloric acid solution (concentration of 0.12 mol / L) through a syringe to solidify the colloid. The colloid was then washed with water until neutral and dried to obtain GO / RCWP fibers (aspect ratio of 250-750:1) for later use.
[0071] The obtained GO / RCWP fibers, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.3 wt.% hydrogen peroxide solution, and 0.5 mL of 21.25 mg / mL copper chloride solution were added to a 100 mL polytetrafluoroethylene reactor liner and stirred evenly; a hydrothermal reaction was carried out at 180°C for 8 h; and after the reaction was completed, the mixture was cooled to room temperature to obtain a porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic copper.
[0072] Example 3
[0073] A porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single-atom copper is prepared by the following steps:
[0074] First, 280 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (the mass ratio of urea, NaOH, and H2O was 1:2:8) under stirring conditions, and then 40 mg of a 9.99 mg / mL graphene oxide dispersion was added. The mixture was then ice-bathed to obtain a black viscous colloid. The obtained viscous colloid was squeezed into a dilute hydrochloric acid solution (concentration of 0.12 mol / L) through a syringe to solidify it into a shape. The colloid was then washed to neutrality and dried to obtain GO / RCWP fibers (aspect ratio of 333 to 1000:1) for later use.
[0075] The obtained GO / RCWP fibers, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.3 wt.% hydrogen peroxide solution, and 0.5 mL of 21.25 mg / mL copper chloride solution were added to a 100 mL polytetrafluoroethylene reactor liner and stirred evenly; the mixture was hydrothermally reacted at 180°C for 8 h, and after the reaction was completed, it was cooled to room temperature to obtain a porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic copper.
[0076] Example 4
[0077] A porous graphene- / regenerated cellulose composite catalytic fiber material loaded with single-atom cobalt is prepared by the following specific steps:
[0078] First, 300 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (the mass ratio of urea, NaOH, and H2O was 1:2:8) under stirring conditions. 40 mg of a 9.99 mg / mL graphene oxide dispersion was then added and ice-bathed to obtain a black viscous colloid. The resulting viscous colloid was squeezed into a dilute hydrochloric acid solution through a syringe to solidify and form, then washed to neutrality and dried to obtain GO / RCWP fibers for later use.
[0079] The obtained GO / RCWP fibers, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.3 wt.% hydrogen peroxide solution, and 1 mL of 3.95 mg / mL cobalt nitrate solution were added to a 100 mL polytetrafluoroethylene reactor liner and stirred evenly; the mixture was hydrothermally reacted at 180°C for 8.5 h, and after the reaction was completed, it was cooled to room temperature to obtain a porous graphene / regenerated cellulose composite catalytic material loaded with single atomic cobalt.
[0080] Example 5
[0081] A porous graphene- / regenerated cellulose composite catalytic fiber material loaded with copper-molybdenum diatoms, the specific preparation steps of which are as follows:
[0082] First, 300 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (the mass ratio of urea, NaOH, and H2O was 1:2:8) under stirring conditions. 40 mg of a 9.99 mg / mL graphene oxide dispersion was then added and ice-bathed to obtain a black viscous colloid. The resulting viscous colloid was squeezed into a dilute hydrochloric acid solution through a syringe to solidify and form, then washed to neutrality and dried to obtain GO / RCWP fibers for later use.
[0083] The obtained GO / RCWP fibers, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.3 wt.% hydrogen peroxide solution, 6.6 mg of copper chloride, and 9.7 mg of ammonium molybdate were added to a 100 mL polytetrafluoroethylene reactor liner and stirred evenly; the mixture was hydrothermally reacted at 180°C for 8 h, and after the reaction was completed, it was cooled to room temperature to obtain a porous graphene / regenerated cellulose composite catalytic material loaded with copper-molybdenum diatoms.
[0084] Figure 8 Spherical aberration corrected scanning transmission electron micrograph of the double single-atom composite catalytic fiber prepared in Example 5.
[0085] Comparative Example 1
[0086] A nitrogen-doped graphene / regenerated fiber composite catalyst, the specific preparation steps are as follows:
[0087] First, under stirring conditions, 300 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (mass ratio of 1:2:8), and then 40 mg of graphene oxide with a concentration of 9.99 mg / mL was added. An ice bath was obtained to obtain a black viscous colloid. The mixture was squeezed into a dilute hydrochloric acid solution (same as in Example 1) with a syringe to solidify and form, and then washed to neutrality and dried to obtain a nitrogen-doped graphene / regenerated fiber composite catalyst.
[0088] The fixed bed system of the catalyst prepared in this comparative example only achieved 55.5% 4-NP conversion even at a flow rate of 4.8 mL / min.
[0089] Comparative Example 2
[0090] A porous graphene- / regenerated cellulose composite catalytic particle fiber material loaded with N / O co-coordinated single atomic copper, the specific preparation steps are as follows:
[0091] First, 300 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (the mass ratio of urea, NaOH, and H2O was 1:2:8) under stirring, and then 40 mg of a 9.99 mg / mL graphene oxide dispersion was added. The mixture was ice-bathed to obtain a black viscous colloid. The obtained viscous colloid was extruded through a syringe into granular fibers with a length of 5 mm (aspect ratio less than 50) and squeezed into a dilute hydrochloric acid solution (same as in Example 1) for solidification. The fibers were then washed until neutral and dried to obtain GO / RCWP granular fibers for later use.
[0092] The obtained GO / RCWP granular fibers, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.3 wt.% hydrogen peroxide solution, and 0.5 mL of 21.25 mg / mL copper chloride solution were added to a 100 mL polytetrafluoroethylene reactor liner and stirred evenly; the mixture was hydrothermally reacted at 180°C for 8 h, and then cooled to room temperature after the reaction to obtain a copper-loaded porous graphene / regenerated cellulose composite granular catalytic material. When catalyzing 4-NP, the material exhibited a large flow resistance, and the degree of embedding of the flaky porous graphene NHG into RCWP was low. At the same time, when subjected to severe scouring during the flow catalysis process, the porous graphene loaded with single-atom copper was easily detached from the composite particles, significantly reducing the cyclic stability of the catalyst.
[0093] Comparative Example 3
[0094] A porous graphene- / regenerated cellulose composite catalytic fiber material loaded with N / O co-coordinated single-atom copper is prepared by the following specific steps:
[0095] First, 300 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (the mass ratio of urea, NaOH, and H2O was 1:2:8) under stirring, and then 40 mg of a 9.99 mg / mL graphene oxide dispersion was added, and an ice bath was used to obtain a black viscous colloid. The obtained viscous colloid was extruded through a syringe into a dilute hydrochloric acid solution for solidification, and then washed to neutrality and dried to obtain GO / RCWP fibers (the aspect ratio condition was equivalent to that in Example 1) for use.
[0096] The obtained GO / RCWP fibers, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.3 wt.% hydrogen peroxide solution, and 0.5 mL of 21.25 mg / mL copper chloride solution were added to a 100 mL polytetrafluoroethylene reactor liner and stirred evenly. The reaction was hydrothermally reacted at 180°C for 5.5 h, and then cooled to room temperature. Insufficient hydrothermal time during the catalyst preparation process directly affected the nitrogen doping amount. The reduced nitrogen doping amount led to a decrease in the metal loading, thereby reducing the catalytic activity of the catalyst.
[0097] Comparative Example 4
[0098] A porous graphene- / regenerated cellulose composite catalytic fiber material loaded with N / O co-coordinated single-atom copper is prepared by the following specific steps:
[0099] First, 900 mg of regenerated cellulose was dissolved in 5 mL of a mixed solution of urea and NaOH (the mass ratio of urea, NaOH, and HO was 1:2:8) under stirring, and then 40 mg of a 9.99 mg / mL graphene oxide dispersion was added. The mixture was then ice-bathed to obtain a black viscous colloid. The obtained viscous colloid was squeezed into a dilute hydrochloric acid solution through a syringe to solidify and form, and then washed to neutrality and dried to obtain GO / RCWP fibers (the aspect ratio condition was equivalent to that in Example 1) for later use.
[0100] The obtained GO / RCWP fibers, 2.1 mL of 28 wt.% ammonia water, 2 mL of 0.3 wt.% hydrogen peroxide solution, and 0.5 mL of 21.25 mg / mL copper chloride solution were added to a 100 mL polytetrafluoroethylene reactor liner and stirred evenly. The mixture was hydrothermally reacted at 180°C for 8 h and then cooled to room temperature after the reaction was completed.
[0101] After testing, the loading rate of metallic copper in the obtained composite catalytic fiber material was significantly reduced, and the accessibility of the active sites was reduced, which ultimately led to a sharp drop in the catalytic reduction activity of the composite material for 4-nitrophenol (4-NP).
[0102] Application Example 1
[0103] 977 mg of the composite catalytic fiber prepared in Example 1 was placed in a glass column to form a fixed bed system. 20 mL of a mixed aqueous solution consisting of 0.16 mmol of p-nitrophenol and 605 mg of sodium borohydride was added to the fixed bed reaction system. After flowing through the fixed bed catalyst, the solution turned colorless after 47 seconds. The flow rate was 25.5 mL min -1 (See Table 2.) Compared to other metal-based catalytic systems, it exhibits an excellent processing speed.
[0104] Table 2 Comparison of the performance of the composite catalytic fibers obtained in the present invention and other metal-based catalytic systems for 4-NP reduction
[0105]
[0106]
[0107] The references cited in Table 1 are as follows:
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[0116] Application Example 2
[0117] In order to study the substrate universality of the catalytic reduction reaction in the fixed bed system, the catalysis was extended to various nitroaromatic derivatives. The specific conditions and catalytic effects are shown in Table 3.
[0118] Table 3 Performance test of reduction of nitroaromatic compounds by NaBH4 using Cu1 / NHG-RCWP catalyst
[0119]
[0120] Application Example 3
[0121] Using the composite catalytic fiber prepared in Example 1, 1.954 mg of the Cu1 / NHG-RCWP composite catalytic fiber was loaded into a fixed-bed column. The fixed-bed system was heated to 75°C using an electric heating mantle to catalytically degrade 2.283 mg of BPA (bisphenol A). Further investigation of the catalytic performance of the Cu1 / NHG-RCWP composite catalytic fiber using 310 μL (33 wt.% H2O2) as an oxidant revealed that the Cu1 / NHG-RCWP composite catalytic fiber completely degraded BPA within 1 minute 52 seconds. This demonstrates superior processing speed compared to other metal-based catalytic systems (see Table 4).
[0122] Table 4 Comparison of BPA degradation performance of the catalyst prepared by the present invention and other metal-based catalytic systems
[0123]
[0124] The references cited in Table 3 are as follows:
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[0131] NHM hydrogen spectrum is used to detect the process of catalytic degradation, such as Figure 10 .
[0132] Application Example 4
[0133] 977 mg of the composite catalytic fiber prepared in Example 1 was filled into a glass column (packing density of 0.288 g / cm 3 ), forming a fixed-bed system. A 20 mL aqueous mixture consisting of 0.1 mmol of an aromatic nitro compound and 378 mg of sodium borohydride was added to the fixed-bed reaction system. The column was heated to 65°C using a heating mantle. After flowing through the fixed-bed catalyst, liquid phase analysis was performed to analyze its conversion rate. The specific flow rates are shown in Table 5. The performance is as follows:
[0134] Table 5 Performance test of reduction of nitroaromatic compounds by NaBH4 using Cu1 / NHG-RCWP composite catalytic fiber
[0135]
[0136] The above contents are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent replacement or modification of the present invention by those skilled in the art within the technical scope disclosed in the present invention based on their technical solutions and improved concepts shall be deemed to fall within the scope of protection of the present invention.
Claims
1. A porous graphene / cellulose composite catalytic material loaded with N / O co-coordinated single-atom metals, comprising a porous fiber skeleton formed by winding cellulose fibers and a graphene sheet and N / O co-coordinated single-atom metals composited therein, wherein the single-atom metal is one or more of Cu, Bi, Ru, Zn, Mo, Co, Ni, and Fe.
2. The porous graphene / cellulose composite catalytic material loaded with N / O co-coordinated single-atom metal according to claim 1, characterized in that: The composite catalytic material is in a fiber shape, and its aspect ratio is 160-1500:
1.
3. The porous graphene / cellulose composite catalytic material loaded with N / O co-coordinated single-atom metal according to claim 1, characterized in that: The diameter of the porous fiber skeleton is 0.2-0.5 mm; the diameter of a single cellulose fiber is 3-20 μm.
4. The porous graphene / cellulose composite catalytic material loaded with N / O co-coordinated single-atom metal according to claim 1, characterized in that: The pore diameter of the composite catalytic material is 10-100 nm.
5. The porous graphene / cellulose composite catalytic material loaded with N / O co-coordinated single-atom metal according to claim 1, characterized in that: In the composite catalytic material, the N element content reaches 1.0-8.9 at%, the O element content reaches 8.5-27.75 at%, and the single-atom metal content reaches 0.2-7.0 at%.
6. The method for preparing the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal according to any one of claims 1 to 5, characterized in that: The steps include: 1) adding graphene oxide to a cellulose solution under stirring to obtain a viscous solution; then extruding the solution into a coagulation bath and solidifying it to prepare a GO / RCWP composite fiber; 2) uniformly mixing hydrogen peroxide, a nitrogen source, and a non-precious metal salt solution, adding GO / RCWP composite fibers to the resulting mixture, sealing, performing a hydrothermal reaction, washing, and drying to obtain the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single atomic metal.
7. The preparation method according to claim 6, characterized in that The mass ratio of the introduced graphene oxide to cellulose is 1:6.75-8.
00.
8. The preparation method according to claim 6, characterized in that The mass ratio of the introduced non-noble metal salt to graphene oxide, hydrogen peroxide, and nitrogen source is 1:(3.76-4.71):(0.62-1.71):(52.71-105.41).
9. The preparation method according to claim 6, characterized in that The temperature of the hydrothermal reaction is 170-180° C., and the time is 6.5-8.5 hours.
10. Use of the porous graphene / regenerated cellulose composite catalytic material loaded with N / O co-coordinated single-atom metal according to claim 1 in catalyzing the reduction reaction of aromatic nitro compounds and the degradation reaction of bisphenol A.