CN114700063A - Assembled type catalytic filler, preparation method thereof and application thereof in flow chemical catalytic system - Google Patents

Assembled type catalytic filler, preparation method thereof and application thereof in flow chemical catalytic system Download PDF

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CN114700063A
CN114700063A CN202210335227.6A CN202210335227A CN114700063A CN 114700063 A CN114700063 A CN 114700063A CN 202210335227 A CN202210335227 A CN 202210335227A CN 114700063 A CN114700063 A CN 114700063A
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fiber
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奚江波
胡晗宇
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Wuhan Institute of Technology
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    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
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    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
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    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/18—Carbon
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
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    • C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
    • C07C209/325—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups reduction by other means than indicated in C07C209/34 or C07C209/36
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Abstract

The invention discloses an assembled body type catalytic filler, which is a composite hydrogel assembly catalyst with a multistage porous structure prepared by a one-step hydrothermal method by taking graphene oxide and fiber materials as main assembly raw materials, water-soluble micromolecule organic matters as a wetting agent, ammonia water as a nitrogen source and hydrogen peroxide as a pore forming agent. The assembled catalytic filler obtained by the invention can show excellent catalytic reaction efficiency without the traditional modification means such as introducing active metal and the like, has good mechanical property and cycle stability, and can provide a new idea for preparing a high-performance flow chemical system catalyst; the preparation method is simple, raw materials are easy to obtain, the requirement on equipment is low, the condition is mild, the production cost is low, and the method is suitable for popularization and application.

Description

Assembled type catalytic filler, preparation method thereof and application thereof in flow chemical catalytic system
Technical Field
The invention belongs to the technical field of catalysis, and particularly relates to an assembled catalytic filler, a preparation method thereof and application thereof in a flow chemical catalytic system.
Background
Flow chemistry systems (e.g., fixed bed catalysis) are flow catalysis systems that achieve continuous reactions by holding a catalyst in a particular flow position and allowing a reaction mixture to flow continuously through the catalyst. The flow chemical catalysis system constructed by the filling type catalyst has the advantages of easy product separation, simple operation and the like, and is an ideal industrial production system. As the core of the flow chemical catalytic system, the activity of the catalytic filler is closely related to the quantity of exposed active sites, micro-nano structure and the synergistic effect among components. However, the conventional granular catalyst is not easy to expose active sites due to its compact packing state, and has small gaps and large flow resistance, which is not beneficial to mass transfer and limits the catalytic activity and the throughput of the flow chemical catalytic system.
In recent years, there has been some new exploration in the design, preparation and system construction of new flow chemical catalysts. Vertically growing nano gold wires on the glass fibers to prepare high-performance catalytic fibers; the catalyst is filled in a column tube to construct a fixed bed system for catalytic reduction of p-nitrophenol (4-NP), and the flow rate can reach 32mL/min (Strategy for nano-catalysis in a fixed-bed system. advanced Materials,2014,26, 4151-4155). Wang and the like use a polydopamine functionalized cotton fiber as a substrate to load palladium nanoparticles to prepare a novel high-performance catalytic fiber; the solid phase was loaded into a column to construct a 4-NP catalytic reduction fixed bed system, and the flow rate was increased to 60mL/min (Mussel-amplified functional amplification of bottom for nano-catalyst support and its application in a fixed-bed system with high performance. scientific Reports,2016,6, 1-8). King et al prepared bimetallic Pd-Fe alloy nanoparticle catalysts anchored on N-doped carbon (NC) functionalized fibrous Aluminum Silicate Fibers (ASFs) and constructed a high performance fixed bed catalytic system useful for catalytic reduction of organic dyes with flow rates up to 200mL/min [ Continuous flow reduction of organic dyes over Pd-Fe alloyed based catalytic in a fixed-bed system chemical Engineering Science,2021,231,116303 ]. However, the catalytic filler mainly utilizes active metals to catalyze the reaction, but the introduced nano metals are easy to agglomerate, so that the effective surface area of the catalyst is easy to reduce, thereby reducing the catalytic performance, and the use of metals, especially noble metals, faces the pressure of environmental protection and cost. The industry needs to further explore a catalytic filler without metal active components, which has high activity and good cycling stability and can realize continuous reaction, and the catalytic filler is used for constructing a flow chemical catalytic system.
Disclosure of Invention
The invention aims to provide an assembled catalytic filler aiming at the problems and the defects in the prior art, and the assembled catalyst is prepared by a simple method only through a one-step hydrothermal method and is used for constructing a flow chemical catalytic system; the related synthesis process is simple, the operation is convenient, the reaction materials are cheap, the flow resistance is small, the catalytic performance is strong, the post-treatment is simple after the catalyst is used, and the use cost and the post-treatment cost of the catalyst can be effectively reduced.
In order to achieve the purpose, the invention adopts the technical scheme that:
a preparation method of an assembled type catalytic filler comprises the following steps: under the condition of stirring, adding a fiber material, a wetting agent, a hydrogen peroxide solution and a liquid nitrogen source into the graphene oxide dispersion liquid, uniformly mixing, carrying out hydrothermal reaction, and cooling to form an assembled hydrogel, thereby obtaining the assembled catalytic filler.
In the scheme, the diameter of the fiber material is 100nm-100 μm, and the length-diameter ratio is 10-1000; one or more of cellulose fiber, aluminum silicate fiber, glass fiber, quartz cotton fiber, carbon fiber and synthetic fiber can be selected.
In the scheme, the wetting agent is one or more of methanol, ethanol, propanol, isopropanol, acetone and the like.
In the scheme, the concentration of the graphene oxide dispersion liquid is 3-10 mg/mL.
In the scheme, the sheet diameter of the graphene oxide is 10nm-40 μm.
In the scheme, the concentration of the hydrogen peroxide solution is 0.3-30 wt%.
In the scheme, the liquid nitrogen source can be ammonia water and the like; the concentration is 28-30%.
In the scheme, the graphene oxide, the wetting agent and the H are introduced into the raw materials2O2The mass ratio of the nitrogen source to the fiber material is 1 (0.5-3): (0.045-5): 0.05-30): 1.87-5.62.
In the scheme, the temperature of the hydrothermal reaction is 120-220 ℃, and the time is 5-24 h.
The assembled catalytic filler prepared according to the scheme is of a three-dimensional porous three-dimensional structure formed by self-assembling and lapping fiber materials and nitrogen-doped porous graphene; wherein the pore size in the nitrogen-doped porous graphene is 1-10 nm; the fiber substrate has good structural support and mechanical property strengthening effect on the assembly.
The assembled catalytic filler obtained by the scheme is used as a fixed bed catalyst for efficiently catalyzing the reduction reaction of the aromatic nitro compound, and the method comprises the following specific steps: filling the assembled catalytic filler in a chromatographic column, and allowing the reduction reaction solution of the aromatic nitro compound to pass through the assembled catalytic filler at the flow rate of 30-240 mL/min; the catalytic efficiency can reach more than 98 percent.
In the scheme, the aromatic nitro compound can be selected from 4-nitrophenol, 4-nitrobromobenzene, 4-nitrochlorobenzene, 3-nitrobromobenzene, 3-nitrochlorobenzene, 4-nitrobenzoic acid or 4-nitroaniline and the like.
In the scheme, the concentration of the aromatic nitro compound in the reduction reaction solution of the aromatic nitro compound is 0.1-5 mmol/L.
The method takes graphene oxide and fiber materials as main assembly raw materials, water-soluble micromolecule organic matters as wetting agents, ammonia water as nitrogen sources and hydrogen peroxide as pore-forming agents; the wetting agent introduced into the fiber material can improve the wettability and the internal porosity of the fiber material so as to promote the assembly of graphene oxide on fibers, form a uniform porous structure, and simultaneously physically peel off fiber groups into a fiber bundle so as to improve fiber gaps so that the nano-scale graphene oxide can effectively enter a fiber three-dimensional network; then, the nano-scale graphene oxide is driven to be assembled with a fiber three-dimensional network through hydrothermal reaction, and the preparation of the nitrogen-doped graphene and the construction of a fiber material-nitrogen-doped graphene three-dimensional self-assembled porous integral structure are synchronously realized; the introduced fiber material can further effectively improve the flow performance of the assembled catalytic filler; the fiber is used as a support, so that the damage of the whole structure of the filler and the stacking of the nitrogen-doped graphene sheet layers caused by the overlarge pressure of the reaction liquid in a flowing system can be prevented, and the exposure of active sites among the sheet layers can be shielded; the introduced fiber material can effectively enlarge the specific surface area and the aperture of the obtained graphene-based composite material while enhancing the mechanical property of the assembly by locking the graphene sheets through a network structure, prevent the graphene from being seriously stacked in the synthesis and use processes, facilitate the exposure of more nitrogen-doped graphene active sites (defects can be increased), synchronously improve the mechanical property, the catalytic activity and the medium circulation property of the obtained assembly type catalytic filler, and further obviously improve the catalytic reaction efficiency of the obtained assembly type catalytic filler.
In addition, the assembled catalytic filler disclosed by the invention can further show excellent cycle stability without modification means such as introduction of active metal.
Compared with the prior art, the invention has the beneficial effects that:
1) the synthesis process is simple, the preparation of the active component (nitrogen-doped graphene) and the assembly of the three-dimensional porous result formed by the active component and the fiber material are realized by adopting a one-step method, the production efficiency is high, and the operation is convenient; the related raw materials are simple and easy to obtain, the reaction condition is mild, the instrument is simple and convenient, the cost is low, and the method is suitable for popularization and application;
2) the nitrogen-doped porous graphene formed in the assembled catalyst can provide certain catalytic activity, the porous multi-stage structure of the catalyst is favorable for mass transfer, and the introduced catalyst can further effectively improve the flow performance (small physical resistance and large flow capacity) of the assembled catalytic filler; meanwhile, more nitrogen-doped graphene active sites are exposed; the catalyst is applied to a fixed bed catalytic system, realizes continuous catalytic reaction and can show excellent catalytic reaction efficiency; and modification means such as active metal and the like are not required to be introduced, so that a new idea can be provided for the preparation of the high-performance flow chemical system catalyst;
3) the assembled catalyst has better mechanical property and can adapt to various filling environments; the catalyst has good cycling stability, can still maintain stronger catalytic activity after being used for many times (without the traditional active metal modification means), and is convenient to separate and recycle after being used and environment-friendly.
Drawings
FIG. 1 is a flow chart of the preparation of the nitrogen-doped porous graphene-alumina silicate fiber assembly catalyst in the present invention;
in fig. 2, a is a scanning electron microscope image and a real object photograph of the hydrogel of the nitrogen-doped porous graphene-aluminum silicate fiber assembly obtained in example 1, b is a high resolution scanning electron microscope image of the hydrogel of the nitrogen-doped porous graphene-aluminum silicate fiber assembly obtained in example 1, c is a transmission electron microscope image of the nitrogen-doped porous graphene-aluminum silicate fiber assembly, d is a transmission electron microscope image of the nitrogen-doped porous graphene peeled from the graphene-aluminum silicate fiber assembly obtained in example 1, and e is an element surface scan image of carbon, nitrogen and oxygen elements of the nitrogen-doped porous graphene peeled from the graphene-aluminum silicate fiber assembly obtained in example 1;
FIG. 3 is a graph comparing assembled catalytic filler of the type obtained in example 1 (aluminum silicate-containing fibers) with pure nitrogen-doped porous graphene;
FIG. 4 is a comparison graph of photoelectron spectrum and Raman spectrum of the nitrogen-doped porous graphene-alumina silicate fiber assembly obtained in example 1;
fig. 5 is BET test results of the nitrogen-doped porous graphene-aluminum silicate fiber assemblies (NHG-ASFs), the ultrasonically exfoliated pure nitrogen-doped porous graphene (shng), and the direct hydrothermal synthesis of pure nitrogen-doped porous graphene (NHG) obtained in example 1;
in fig. 6, a and b are graphs of a real object before and after continuous flow reduction of p-nitrophenol by a fixed bed catalytic system constructed by the nitrogen-doped porous graphene-alumina silicate fiber assembly obtained in example 1, c is a graph of ultraviolet/visible absorption spectrums before and after reduction of p-nitrophenol, and d is a graph of cycle stability of the nitrogen-doped porous graphene-alumina silicate fiber assembly;
fig. 7 is a physical diagram of fixed bed catalytic graphene simply filled with nitrogen-doped porous graphene.
Detailed Description
In order to better understand the present invention, the following embodiments are further illustrated, but the present invention is not limited to the following embodiments.
In the following examples, the graphene oxide used is a self-made product according to Hummers method; specifically, the Preparation is described in the "Preparation of graphic oxide. journal of the American Chemical Society,1958,208, 1334-1339"; the sheet diameter is 10nm-40 μm.
In the following examples, the preparation flow chart of the assembled catalyst is shown in fig. 1, and specifically includes the following steps: firstly, respectively adding loose fibers, a wetting agent, 0.3-30% of hydrogen peroxide and 28-30% of ammonia water into a graphene dispersion liquid which is subjected to ultrasonic treatment in advance, and uniformly mixing; heating the obtained mixed solution to 120-220 ℃ for hydrothermal reaction for 5-24H to finally obtain the nitrogen-doped porous graphene-aluminum silicate fiber assembly hydrogel, wherein the graphene oxide, the wetting agent and the H are introduced into the raw materials2O2The mass ratio of the nitrogen source to the fiber material is 1 (0.5-3): (0.045-5): 0.05-30): 2.21-5.62.
In the following examples, the diameter of the aluminum silicate fiber used is 100nm-100 μm, the length-diameter ratio is 10-1000, and the length-diameter ratio is 50-500; the diameter of the adopted cellulose fiber (cotton) is 100nm-100 μm, and the length-diameter ratio is 20-100.
Example 1
An assembled catalytic filler is prepared from graphene oxide, wetting agent, aluminium silicate fibres and H2O2、NH3·H2The mass ratio of O is 1:0.8:3.75:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in an inner container of a 100mL polytetrafluoroethylene reaction kettle, and 1000mg of loose aluminum silicate fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-aluminum silicate fiber (NHG-ASFs) assembly hydrogel.
The nitrogen-doped porous graphene-alumina silicate fiber assembly hydrogel obtained in the embodiment is subjected to SEM, TEM and XPS tests, and the results are characterized, and are shown in fig. 2 and 4. The graphene oxide nanosheets and the aluminum silicate fibers can be assembled to form three-dimensional mixed integral hydrogel after hydrothermal reaction, the scanning electron microscope image proves that the mixed integral hydrogel presents an integral form with an aluminum silicate network and nitrogen-doped porous graphene sheets which are connected with each other, and the transmission electron microscope can see the fine structure of the nitrogen-doped porous graphene sheets assembled on the aluminum silicate fiber substrate; micro pores ranging from several micrometers to several tens of micrometers, which are randomly distributed, can be observed on the surface of the nitrogen-doped porous graphene single-sheet layer. The x-ray photoelectron spectroscopy analysis shown in fig. 4 indicates that the prepared nitrogen-doped porous graphene (pure nitrogen-doped porous graphene ultrasonically exfoliated from the product, abbreviated as s-NHG) is doped with 82.23 wt.% of carbon element, 8.9 wt.% of oxygen element, and 8.87 wt.% of nitrogen element.
As can be seen from fig. 3, the volume of pure nitrogen-doped porous graphene (NHG for short, prepared by direct hydrothermal synthesis in the same manner as in example 1 except that no alumina silicate fiber is introduced) is much smaller than that of the nitrogen-doped porous graphene-alumina silicate fiber assembly obtained in this example.
FIG. 5 is a graph showing the desorption of nitrogen gas and the distribution of pore size of the nitrogen-doped porous graphene-alumina silicate fiber assembly obtained in this example, and the results show that pure nitrogen-doped porous graphene-alumina silicate fiber assembly is ultrasonically stripped from the productThe specific surface area of the graphene is higher than that of the pure nitrogen-doped porous graphene which is directly hydrothermally synthesized, and is 411.1m2 g-1And 329.7m2 g-1(ii) a The obtained assembly contains more macroscopic holes and has larger substrate mass, so the specific surface area is lower by 16.5m2 g-1The corresponding pore volume of the nano-scale pores is lower; the aperture of the nitrogen-doped porous graphene in the obtained assembly is about 2-6 nm.
The nitrogen-doped porous graphene-alumina silicate fiber assembly hydrogel obtained in the embodiment is used as a fixed bed catalyst, and is filled in a chromatographic column to be used for reducing p-nitrophenol in a fixed bed catalytic system; the specific preparation and application effects are shown in figure 6. In fig. 6, a and b are physical diagrams of prepared nitrogen-doped porous graphene-alumina silicate fiber assemblies packed in a chromatographic column for reducing p-nitrophenol by a fixed bed catalytic system (fixed bed catalytic system based on the nitrogen-doped porous graphene-alumina silicate fiber assemblies); and c is a graph of the ultraviolet/visible absorption spectrum of reduced p-nitrophenol at 0s and 40 s. A mixed solution (20mL) of bright yellow p-nitrophenol and a reducing agent sodium borohydride (378.0mg) became colorless after passing through the fixed bed catalyst nitrogen-doped porous graphene-alumina silicate fiber assembly, and the reduction product was p-aminophenol, which was confirmed by uv/vis absorption spectroscopy. Fig. 6d is a graph of the cycling stability of the nitrogen-doped porous graphene-alumina silicate fiber assembly obtained in the embodiment, and it can be seen that the catalytic efficiency of the catalyst has no obvious change after the nitrogen-doped porous graphene-alumina silicate fiber assembly is recycled for 15 times, which can indicate that the assembly has strong cycling stability, long service life, starts to decrease after no more than 10 times of stability tests compared with most metal-containing catalysts, and has the characteristic of high-strength reuse. When the pure nitrogen-doped porous graphene is adopted (the filling effect of the fixed bed is shown in fig. 7), the whole structure is easy to damage due to no support body, the nitrogen-doped porous graphene sheets are stacked on the fixed bed after being crushed, the flow resistance is large (3mL/min, shown in table 1), and the production efficiency is low.
The assembled catalytic filler obtained in the embodiment has strong mechanical property and is easy to fill; the flow rate of the reduced p-nitrophenol can reach 30mL/min (shown as NHG-ASFs-1 in Table 1), and even 240mL/min (shown as NHG-ASFs-2 in Table 1) when the flow catalytic reduction reaction is carried out by adopting a p-nitrophenol solution with lower concentration, which belongs to one of the fixed bed catalytic systems with the highest flow rate reported at present; in addition, the active component of the catalyst used in the invention is a carbon material, and the catalyst is an environment-friendly and green metal-free catalyst system.
Table 1 comparison of the performances of the carbon-based fixed bed catalytic system obtained according to the invention with those of the traditional metal-based catalytic system
Figure BDA0003574161360000061
Figure BDA0003574161360000071
Among these, the references cited in table 1 are specifically as follows:
[1]Continuous flow reduction of organic dyes over Pd-Fe alloy based fibrous catalyst in a fixed-bed system.Chemical Engineering Science,2021,231,116303.
[2]Strategy for nano-catalysis in a fixed-bed system.Advanced Materials,2014,26,4151-4155.
[3]Mussel-inspired functionalization of cotton for nano-catalyst support and its application in a fixed-bed system with high performance.Scientific Reports,2016,6,1-8.
[4]Catalytic membranes prepared using layer-by-layer adsorption of polyelectrolyte/metal nanoparticle films in porous supports,Nano Letters,2006,6,2268-2272.
[5]Conformally anchoring nanocatalyst onto quartz fibers enables versatile microreactor platforms for continuous-flow catalysis,Science China Chemistry,2021,64,1596-1604.
[6]Capillary-bound dense micelle brush supports for continuous flow catalysis,Angewandte Chemie International Edition,2021,60,24637-24643.
[7]Flow fine synthesis with heterogeneous catalysts,Tetrahedron,2018,74,1705-1730.
[8]Monolithic carbon foam-supported Au nanoparticles with excellent catalytic performance in a fixed-bed system,New Journal of Chemistry,2017,41,15027-15032.
the carbon-based fixed bed catalytic system obtained in the embodiment is further applied to other aromatic nitro compounds, and specific conditions and catalytic effects are shown in table 2.
TABLE 2 catalysis of NaBH using NHG-ASFs assemblies4Performance test results of reduced nitroaromatic compounds
Figure BDA0003574161360000072
Figure BDA0003574161360000081
Wherein standard reaction conditions are employed including: 0.06mmol of nitrobenzene or substituted nitrobenzene, 20mL of H at room temperature2O/ethanol-1/9 (v/v), 6mmol NaBH4(ii) a The content was determined by HPLC.
As can be seen from Table 2, the assembly-type catalytic filler obtained in the examples has a single-treatment yield of 89% or more at 30ml/min for various nitroaromatic compounds.
Example 2
An assembled catalytic filler is prepared from graphene oxide, wetting agent, aluminium silicate fibres and H2O2、NH3·H2The mass ratio of O is 1:1.2:1.87:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in a liner of a polytetrafluoroethylene reaction kettle with 100mL, and 500mg of loose aluminum silicate fiber, 1.5mL of acetone, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-aluminum silicate fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst, the flow rate is 13.3mL/min, and the conversion rate of p-nitrophenol (20mL,5.0mmol/L) is 100%.
Example 3
An assembled catalytic filler is prepared from graphene oxide, wetting agent, aluminium silicate fibres and H2O2、NH3·H2The mass ratio of O is 1:0.8:2.8:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in a liner of a polytetrafluoroethylene reaction kettle with 100mL, and 750mg of loose aluminum silicate fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-aluminum silicate fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 4
An assembled catalyst filler is prepared from graphene oxide, aluminium silicate fibres, wetting agent and H2O2、NH3·H2The mass ratio of O is 1:0.8:4.68:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in a liner of a polytetrafluoroethylene reaction kettle with 100mL, 1250mg of loose aluminum silicate fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed evenly, the inner container is put into a hydrothermal reaction kettle and undergoes hydrothermal reaction for 8 hours at 180 ℃. And cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-aluminum silicate fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 5
An assembled catalytic filler is prepared from graphene oxide, aluminium silicate fibres and H2O2、NH3·H2The mass ratio of O is 1:0.5:5.62:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put into a 100mL polytetrafluoroethylene reaction kettle inner container, and 1500mg of loose aluminum silicate fiber, 0.6mL of propanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-aluminum silicate fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 6
An assembled catalytic filler is prepared from graphene oxide, wetting agent, aluminium silicate fibres and H2O2、NH3·H2The mass ratio of O is 1:0.8:3.75:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in a liner of a polytetrafluoroethylene reaction kettle with 100mL, and 1000mg of loose aluminum silicate fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 5 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-aluminum silicate fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 7
An assembled catalytic filler is prepared from graphene oxide, aluminium silicate fibres, wetting agent and H2O2、NH3·H2The mass ratio of O is 1:3.75:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in an inner container of a 100mL polytetrafluoroethylene reaction kettle, 1000mg of loose aluminum silicate fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia solution with the concentration of 28 wt% are added under the stirring condition; after being mixed evenly, the inner container is put into a hydrothermal reaction kettle and undergoes hydrothermal reaction for 12 hours at 180 ℃. And cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-aluminum silicate fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 8
An assembled catalytic filler is prepared from graphene oxide, cellulose fibres (cotton), wetting agent and H2O2、NH3·H2The mass ratio of O is 1:0.8:1.87:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in a liner of a polytetrafluoroethylene reaction kettle with 100mL, and 500mg of loose cellulose fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed evenly, the inner container is put into a hydrothermal reaction kettle and undergoes hydrothermal reaction for 8 hours at 180 ℃. And cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-cotton fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 9
An assembled catalytic filler is prepared from graphene oxide, cellulose fibres (cotton), wetting agent and H2O2、NH3·H2The mass ratio of O is 1:0.5:2.8:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in a liner of a polytetrafluoroethylene reaction kettle with 100mL, and 750mg of loose cellulose fiber, 0.6mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-cotton fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 10
An assembled catalytic filler is prepared from graphene oxide, carbon fibres, wetting agent and H2O2、NH3·H2The mass ratio of O is 1:0.8:3.75:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in a liner of a polytetrafluoroethylene reaction kettle with 100mL, and 1000mg of loose carbon fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being uniformly mixed, the inner container is put into a hydrothermal reaction kettle, and the hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-carbon fiber assembly hydrogel. The composite material can be used as a fixed bed catalyst.
Example 11
An assembled catalyst filler is prepared from graphene oxide, wetting agent, glass fiber and H2O2、NH3·H2The mass ratio of O is 1:0.8:3.75:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in an inner container of a 100mL polytetrafluoroethylene reaction kettle, and 1000mg of loose glass fiber, 1mL of ethanol, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain the nitrogen-doped porous graphene-glass fiber assembly hydrogel.
Comparative example 1
An assembled catalyst filler is prepared from graphene oxide, glass fiber and H2O2、NH3·H2The mass ratio of O is 1:3.75:0.08: 12.53; the preparation method comprises the following steps:
46.37mL of graphene oxide dispersion liquid with the concentration of 5.75mg/mL is taken to be put in an inner container of a 100mL polytetrafluoroethylene reaction kettle, and 1000mg of loose glass fiber, 7.2mL of hydrogen peroxide solution with the concentration of 0.3 wt% and 14.0mL of ammonia water solution with the concentration of 28 wt% are added under the stirring condition; after being mixed uniformly, the inner container is put into a hydrothermal reaction kettle, and hydrothermal reaction is carried out for 8 hours at 180 ℃; and cooling to room temperature after the reaction is finished to obtain an assembly, wherein the components in the assembly are distributed unevenly, and a large number of glass fiber clusters are exposed on the surface of the assembly, are easy to damage and are not suitable for filling a fixed bed.
The upper and lower limit values and interval values of the raw materials, the reaction temperature and the time can all realize the invention, and the examples are not necessarily listed here.
The above embodiments are only for illustrating the technical idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention, and not to limit the protection scope of the present invention by this means. All equivalent changes and modifications made according to the spirit of the present invention should be covered in the protection scope of the present invention.

Claims (10)

1. A preparation method of an assembled type catalytic filler is characterized by comprising the following steps: under the condition of stirring, adding a fiber material, a wetting agent, a hydrogen peroxide solution and a liquid nitrogen source into the graphene oxide dispersion liquid, uniformly mixing, carrying out hydrothermal reaction, and cooling to form an assembled hydrogel, thereby obtaining the assembled catalytic filler.
2. The method of claim 1, wherein the fiber material has a diameter of 100nm to 100 μm and an aspect ratio of 10 to 1000; is one or more of cellulose fiber, aluminum silicate fiber, glass fiber, quartz cotton fiber, carbon fiber and synthetic fiber.
3. The preparation method according to claim 1, wherein the wetting agent is one or more of methanol, ethanol, propanol, isopropanol and acetone.
4. The preparation method according to claim 1, wherein the concentration of the graphene oxide dispersion is 3-10 mg/mL; the particle size of the graphene oxide is 10nm-40 mu m.
5. The method according to claim 1, wherein the liquid nitrogen source is ammonia.
6. The method according to claim 1, wherein the graphene oxide, the wetting agent and the H are introduced into the raw material2O2The mass ratio of the nitrogen source to the fiber material is 1 (0.5-3): (0.045-5): 0.05-30): 1.87-5.62.
7. The preparation method as claimed in claim 1, wherein the hydrothermal reaction is carried out at a temperature of 120 ℃ and a temperature of 220 ℃ for 5-24 h.
8. The assembled catalytic filler prepared by the preparation method of any one of claims 1 to 7 is characterized by being in a three-dimensional porous three-dimensional structure formed by self-assembly lap joint of a fiber material and nitrogen-doped porous graphene.
9. The assembled catalytic filler prepared by the preparation method of any one of claims 1 to 7 or the assembled catalytic filler of claim 8, wherein the assembled catalytic filler is used as a fixed bed catalyst for catalyzing reduction reaction of an aromatic nitro compound, and the method comprises the following specific steps: and filling the assembled catalytic filler into a chromatographic column, and allowing the reduction reaction solution of the aromatic nitro compound to pass through the assembled catalytic filler at the flow rate of 30-240 mL/min.
10. The use of claim, wherein the concentration of the aromatic nitro compound in the reduction reaction solution of the aromatic nitro compound is 0.1 to 5 mmol/L.
CN202210335227.6A 2022-03-31 2022-03-31 Assembled type catalytic filler, preparation method thereof and application thereof in flow chemical catalytic system Pending CN114700063A (en)

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