A porous sheet-shaped composite catalyst, a preparation method, a catalytic article and applications

Abstract

The application discloses a porous flaky composite catalyst, a preparation method, a catalytic material and application, and the preparation method of the porous flaky composite catalyst is as follows: terephthalic acid is dissolved in an N.N-dimethylformamide solution to obtain solution A, and FeCl3*6H2O is dissolved in an N.N-dimethylformamide solution to obtain solution B; the solutions A and B are mixed and then transferred into a high-pressure reaction kettle, the high-pressure reaction kettle is placed into an oven for heating, after the reaction in the high-pressure reaction kettle is completed, the oven stops heating, and after the high-pressure reaction kettle is cooled to room temperature, the solid-state component obtained after the reaction is taken out from the high-pressure reaction kettle; the prepared solid-state component is washed and then dried, so that MIL-88B(Fe) powder is obtained; the prepared MIL-88B(Fe) powder is placed into an alkali solution for crystallization treatment, after the crystallization treatment is completed, the MIL-88B(Fe) powder is washed and then dried, so that the porous flaky composite catalyst is obtained, and the obtained catalyst is rich in metal centers with insufficient coordination, so that electrolyte is easy to penetrate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nanocomposite catalysts, and particularly relates to a porous sheet-shaped composite catalyst, a preparation method, a catalytic material and application. BACKGROUND

[0002] 2-nitro-4-methylsulfonylbenzoic acid (NMSBA) is an intermediate in the production of mesotrione and is widely used in the field of pesticides. Mesotrione is considered an environmentally friendly herbicide for corn fields. The biological activity of the herbicide is much better than that of sulcotrione. It has the advantages of wide herbicidal spectrum, high activity, strong miscibility, and safety to post-crop crops. Due to the presence of two strong electron-withdrawing groups, -NO2 and -SO2CH3, on the benzene ring of 2-nitro-4-methylsulfonyl toluene (NMST), the activity of the benzene ring of NMST is reduced, increasing the difficulty of oxidation. Previously, NMST was converted to NMSBA using concentrated nitric acid and concentrated sulfuric acid as the oxidizing agent. This method produces a large amount of NO x or sulfide, and has the characteristics of violent reaction and many by-products. Nitric acid and sulfuric acid not only corrode equipment, but also pollute the environment.

[0003] In addition, various industrial oxidizing agents such as H2O2, KMnO4, NaClO or organic peroxide are preferred oxidizing agents, however, these oxidizing agents are not only relatively expensive, but also produce a large amount of waste. Compared with these oxidizing agents, using oxygen as an oxidizing agent to oxidize NMST to NMSBA is a promising green and environmentally friendly product, containing only H2O by-product. However, so far, the reported catalysts for the oxidation of NMST to prepare NMSBA by this method have relatively low activity, so it is particularly important to develop an effective catalyst system. As a new type of porous material, metal-organic frameworks (MOFs) are a new type of inorganic-organic hybrid microporous crystalline material composed of metal ions and organic ligands. Due to its unique characteristics and functions, it has been applied in many fields such as catalytic oxidation and gas adsorption, however, most of these metal active sites are deeply buried in the MOF framework and cannot be used for catalytic reactions.

[0004] Currently, the method of preparing multifunctional metal oxide / metal peroxide materials by using MOF materials as templates takes advantage of the rich and uniform distribution of metal active sites in the MOF framework, and the structure of the prepared metal oxide / metal peroxide material avoids self-stacking, however, many MOF materials are completely converted into metal oxide / metal peroxide structures through the decomposition of organic ligands, and their structure and morphology are completely destroyed, thereby losing the inherent advantages of MOF materials. SUMMARY

[0005] In order to solve the above technical problems, the purpose of the present application is to provide a preparation method of a porous flaky composite material (FeOOH / Fe3O4 / MOF) prepared by using MOF as a template.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows: a preparation method of a porous flaky composite catalyst, comprising the following steps:

[0007] Step 1: terephthalic acid is dissolved in an N.N-dimethylformamide solution, and after ultrasonic dispersion, an A solution is obtained; FeCl3·6H2O is dissolved in an N.N-dimethylformamide solution, and after ultrasonic dispersion, a B solution is obtained;

[0008] Step 2: the A solution and the B solution are mixed and then transferred to a polytetrafluoroethylene lining of a high-pressure reaction kettle, and after the high-pressure reaction kettle is closed by a stainless steel jacket, it is placed in an oven for heating; after the reaction in the high-pressure reaction kettle is completed, the oven stops heating, and after it cools to room temperature, the solid-state component obtained after the reaction is taken out from the high-pressure reaction kettle;

[0009] Step 3: the solid-state component prepared in step 2 is washed with N,N-dimethylformamide and an alcohol solution respectively for multiple times, and after washing, drying treatment is performed, thereby obtaining a MIL-88B(Fe) powder;

[0010] Step 4: the MIL-88B(Fe) powder prepared in step 3 is placed in an alkali solution for crystallization treatment, and after the crystallization treatment is sufficient, it is washed with an alcohol solution, and after washing, drying treatment is performed, thereby obtaining a FeOOH / Fe3O4 / MOF composite material, which is a porous flaky composite catalyst using MOF as a template.

[0011] In the step 1, the concentration of the A solution is 0.1-0.5 moL / L, and the concentration of the B solution is 0.1-0.5 moL / L.

[0012] In the step 2, the temperature of heating in the oven is 120-180℃, and the reaction time of the high-pressure reaction kettle in the oven is 12-24h.

[0013] In the step 3, the washing times of N,N-dimethylformamide and the alcohol solution are both three times.

[0014] In the steps 3 and 4, the alcohol solution is a methanol solution.

[0015] In the step 4, the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution, and the crystallization treatment time is 4-12h.

[0016] The concentration of the alkali solution is 0.15-1 moL / L.

[0017] The second object of the present application is to provide a porous sheet-shaped composite catalyst prepared by the preparation method described above.

[0018] The third object of the present application is to provide a catalyst in which the porous sheet-shaped composite catalyst described above is attached to the surface of a glass sphere.

[0019] The fourth object of the present application is to provide an application of the porous sheet-shaped composite catalyst described above or the catalyst described above in catalyzing oxidation of NMST into NMSBA.

[0020] Compared with the prior art, the present application has the beneficial effects that: through MOF-mediated topological transformation, a "rose flower"-type catalyst composed of polygonal mesoporous sheet-shaped FeOOH / Fe3O4 / MOF is successfully synthesized; the microstructure of the prepared catalyst exhibits a large number of polygonal pores with clear edges, high crystallinity, resulting in atomic lattice steps and defects, and rich in coordination-unsatisfied metal centers, which makes the electrolyte easy to penetrate to promote the kinetics of mass transfer and charge transfer; the obtained FeOOH / Fe3O4 / MOF catalyst is attached to glass beads, which can realize heterogeneous catalysis in a microchannel reactor, and is conducive to the reuse of the catalyst; in an alkaline environment, the microchannel reactor can use O2 as a clean oxidant to catalyze NMST oxidation into NMSBA in a green NaOH / DMF mixture under mild conditions; the method has low requirements for the material of the device, and is suitable for environmental protection and preparation of more than 100 g. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Scanning electron microscope images of MIL-88B(Fe) and FeOOH / Fe3O4 / MOF prepared in Example 1 of the present application.

[0022] Figure 2 Corresponding TEM images of FeOOH / Fe3O4 / MOF nanosheets prepared in Example 1 of the present application.

[0023] Figure 3 XRD images of MIL-88B(Fe) and FeOOH / Fe3O4 / MOF prepared in Example 2 of the present application.

[0024] Figure 4 A graph showing the change of the catalytic effect of the catalyst in Example 6 of the present application with reaction time;

[0025] Figure 5 An electron microscope image of the FeOOH / Fe3O4 / MOF catalyst in Example 6 of the present application after running for 80 h;

[0026] Figure 6 A structural schematic diagram of the micro-flow channel reaction assembly provided by the present application.

[0027] Figure: 1 reactor, 2 gas cylinder, 3 liquid storage tank, 4 infusion pump, 5 back pressure valve, 6 collection tank, 7 first heater, 8 second heater, 9 pipeline, 10 flow meter, 11 reaction tube, 12 communication pipe. DETAILED DESCRIPTION

[0028] Example 1

[0029] The present embodiment provides a preparation method of a porous flaky composite catalyst, comprising the following steps:

[0030] Step 1: 0.4598 terephthalic acid was dissolved in 15 mL of N.N-dimethylformamide solution, and A solution was obtained after ultrasonic dispersion for 10 min. 0.798 g of FeCl3·6H2O was dissolved in 15 mL of N.N-dimethylformamide solution, and B solution was obtained after ultrasonic dispersion for 10 min;

[0031] Step 2: After mixing A solution and B solution at a volume ratio of 1:1, they were transferred into a polytetrafluoroethylene liner (50 mL specification) of a high-pressure reaction kettle. After the high-pressure reaction kettle was closed by a stainless steel jacket, it was placed in a forced air drying oven at 120°C for 24 h. Then, after it was cooled to room temperature, the solid component obtained after the reaction was taken out of the high-pressure reaction kettle;

[0032] Step 3: The solid component obtained in step 2 was washed with N,N-dimethylformamide and alcohol solution respectively for three times, and then dried in a vacuum oven at 60°C overnight to obtain a red-brown solid powder, which was named as MIL-88B(Fe) powder;

[0033] Step 4: The MIL-88B(Fe) powder obtained in step 3 was added into a 0.15 moL / L sodium hydroxide solution for crystallization for 4 h. After methanol washing, it was placed in a 60°C vacuum drying oven overnight to obtain a FeOOH / Fe3O4 / MOF composite material (i.e. a porous flaky composite catalyst).

[0034] Morphology analysis

[0035] The scanning electron microscope photos of the MIL-88B(Fe) powder and the FeOOH / Fe3O4 / MOF composite material prepared in the present embodiment are shown in Figure 1 As can be seen from the figure, the MIL-88B(Fe) crystal synthesized by a simple solvothermal method has a uniform size, and the MIL-88B(Fe) crystal has a quadrangular pyramid structure and a rough surface. Figure 1 As can be seen from the middle picture a and picture b, the MIL-88B(Fe) crystal synthesized by a simple solvothermal method has a uniform size, and the MIL-88B(Fe) crystal has a quadrangular pyramid structure and a rough surface. Figure 1As shown in images c and d, the structure of the FeOOH / Fe3O4 / MOF composite material has changed from a square pyramid to a "rose" shaped structure. Each "petal" is connected to each other at the bottom and bundled together. Although each "petal" is stacked on top of each other, the sheet-like structure extends outward, thus avoiding natural stacking and preventing a large number of metal active sites in the MOF material from being buried deep in the framework. This two-dimensional sheet-like structure and three-dimensional spherical petal-like structure greatly increase the surface area of ​​the material, which helps to improve catalytic activity.

[0036] Figure 2 TEM images of the FeOOH / Fe3O4 / MOF nanosheets further revealed a large number of mesopores and nanopores on the graphene-like ultrathin FeOOH / Fe3O4 / MOF nanosheets, showing that the edges of the FeOOH / Fe3O4 / MOF are only 3-6 layers thick. Furthermore, the lattice spacings of 0.27 nm and 0.33 nm correspond to the (400) and (310) planes of FeOOH, respectively, and the lattice spacings of 0.28 nm and 0.25 nm correspond to the (220) and (311) planes of Fe3O4, respectively. These results indicate that the FeOOH / Fe3O4 / MOF nanosheets with polygonal mesopores are composed of FeOOH and Fe3O4, explaining a larger specific surface area and numerous heterojunctions. Moreover, this unique and irregular crystal structure not only facilitates the exposure of highly active sites with undercoordinated metal centers but also allows for easy electrolyte permeation, promoting the kinetics of mass transfer and charge transfer.

[0037] Example 2

[0038] Same as Example 1, except that the concentration of sodium hydroxide in step 4 is 0.1 mol / L.

[0039] Morphological analysis

[0040] like Figure 3 In the spectrum shown in image a, five distinct diffraction peaks (9.06°, 10.18°, 16.42°, 17.9°, and 20.1°) can be observed in the diffraction range from 5° to 20°. These correspond to the (002), (101), (103), (202), and (211) crystal planes of MIL-88B(Fe), respectively, confirming the successful synthesis of a low-crystallinity MIL88B(Fe). Figure 3As shown in image b, the peak at 10° in the FeOOH / Fe3O4 / MOF composite is related to the different topologies and crystal structures of Fe-MOFs, suggesting that the composite material retains the precursor MIL-88B(Fe) structure. Furthermore, characteristic absorption peaks for FeOOH (PDF#34-1266) and Fe3O4 (PDF#26-1136) are shown, confirming the preparation of the composite catalyst.

[0041] Example 3

[0042] Similar to Example 1, except that in step 2, the temperature of the drying oven is 180°C and the duration is 12 hours.

[0043] Homemade microchannel reactor

[0044] like Figure 6 As shown, the present invention also provides a microfluidic channel reaction assembly, including a reactor 1, a gas cylinder 2, a storage tank 3, a pump 4, a back pressure valve 5, a collection tank 6, two first heaters 7, and two second heaters 8. The reactor 1 includes two vertically arranged connecting pipes 12 and two reaction tubes 11. Both reaction tubes 11 are vertically arranged and are respectively the first reaction tube and the second reaction tube. The lower end of the first reaction tube is connected to the upper end of the second reaction tube through the connecting pipe 12, and the upper end of the first reaction tube is the feed end of the reactor, and the lower end of the second reaction tube is the discharge end of the reactor. The gas cylinder 2 is used to store compressed oxygen. The inlet of the pump 4 is connected to the storage tank 3, which is used to store the raw material liquid. The outlet of the pump 4 is connected to the gas cylinder. The outlet of reactor 2 is connected to the feed end of reactor 1 via pipe 9. Two second heaters 8 correspond one-to-one with two pipes 9, each second heater 8 heating the corresponding pipe 9. The back pressure valve 5 is located at the discharge end of the reactor. The collection tank 6 collects the material discharged from the reactor discharge end. Both first heaters are heating belts, and both second heaters are heating belts or heating pipes. Two reaction tubes correspond one-to-one with two first heaters, each first heater wound around its corresponding reaction tube. Similarly, two pipes correspond one-to-one with two second heaters, each pipe wound around its corresponding second heater. The second heaters preheat the oxygen or raw material liquid in their respective pipes, while the first heaters heat the corresponding reaction tubes. The reaction tubes are made of stainless steel (316L). The choice of 316L stainless steel for the reactor is primarily due to its superior resistance to high temperatures, high pressures, and alkali corrosion. A flow meter 10 can also be added to the outlet of the gas cylinder. The infusion pump can be a peristaltic pump.

[0045] Catalyst preparation process

[0046] The porous flaky composite catalyst is attached to the surface of the glass ball to obtain a catalytic material, wherein the method for attaching the porous flaky composite catalyst to the surface of the glass ball is as follows: the prepared FeOOH / Fe3O4 / MOF catalyst is ground into a powder, then the powder is mixed with glass balls with a diameter of 0.2 mm, 0.5-1 mL of ethanol is added (so that the catalyst powder is in a paste form, preferably), stirring is performed for 3-5 min, the catalyst is uniformly attached to the surface of the glass ball (the catalyst is electrostatically adsorbed to the surface of the glass ball), and then the glass ball with the catalyst attached to the surface is placed in an oven with a temperature of 60°C for drying.

[0047] Example 4

[0048] The FeOOH / Fe3O4 / MOF catalyst prepared in Example 1 is sampled in an amount of 0.3 g, and a catalytic material is prepared according to the above preparation process of the catalytic material, and the catalytic material is divided and packed in two reaction tubes of the self-made micro-channel reactor. Then, the two first heaters and the second heater are started at the same time, and oxygen is sent out from the gas cylinder, the back pressure valve is fully opened, and the air in the reactor is exhausted by oxygen (i.e. after the gas cylinder is fully opened, the oxygen is blown for about 1 min, and the oxygen flow when the gas cylinder is fully opened is about 500 mL / min), and then the infusion pump is started to add the raw material liquid (the solute of the raw material liquid is NMST and NaOH, the solvent is DMF, and the concentration of NMST is 0.05 moL / L, and the concentration of NaOH is 0.15 moL / L) into the reactor, the flow rate of the raw material liquid is adjusted to 0.2 mL / min, and the back pressure valve is adjusted to make the pressure in the reactor 2.0 MPa, the residence time is 60 min, the reaction temperature and the preheating temperature are both 100°C, and after the reaction is completed, the sample is taken from the discharge end of the reactor for liquid phase analysis, and the results show that the conversion rate of NMST can reach 81.54%, the yield is 42.74%, and the selectivity is 52.41%.

[0049] Example 5

[0050] The same as Example 4, except that the diameter of the glass beads is 4 mm, the FeOOH / Fe3O4 / MOF catalyst is prepared in Example 2, and the reaction residence time is controlled to be 150 min, and after the reaction is completed, the sample is taken from the discharge end of the reactor for liquid phase analysis, and the results show that the conversion rate of NMST can reach 98.21%, the yield of NMSBA is 24.77%, because when the residence time is short, the contact time of oxygen and raw materials is short, and the reaction is incomplete; when the residence time is long, the contact time of oxygen and raw materials in the micro-channel reactor is increased, thereby increasing the conversion rate of NMST. Continuing to increase the residence time leads to excessive oxidation of the product, thereby reducing the selectivity of the reaction.

[0051] The results showed that increasing the diameter of the packing material in the reactor gradually decreased the conversion rate of NMST, while slightly increasing the selectivity of NMSBA. This is because as the diameter of the packing material increases, the interparticle porosity also increases. For the microchannels formed, the distance between channels also increases, leading to increased porosity within the reactor and a decrease in the gas-liquid phase contact area. This results in uneven mass and heat transfer, thus reducing the reactant conversion rate. Simultaneously, due to the smaller gas-liquid phase contact area, excessive oxidation between the two phases is less likely to occur, leading to increased selectivity and reduced byproduct formation.

[0052] Example 6

[0053] Same as Example 4, except that the FeOOH / Fe3O4 / MOF catalyst used was prepared in Example 3, and it was subjected to a continuous reaction (with samples taken every 1 hour for liquid phase analysis within 8 hours after the start of the reaction, and the analysis results are as follows). Figure 4 As shown), from Figure 4 It was observed that the catalyst performance did not significantly decline, thus demonstrating the good stability of FeOOH / Fe3O4 / MOF. At 80 hours of reaction, the reaction was stopped, and the glass beads were removed. Electron microscopy was then performed on the FeOOH / Fe3O4 / MOF catalyst on the glass beads. Figure 5 Images a and b are scanning electron microscope (SEM) images of FeOOH / Fe3O4 / MOF after 80 h of catalysis. It can be seen that the microstructure of FeOOH / Fe3O4 / MOF after the reaction exhibits a plate-like structure. Figure 5 Images c and d are transmission electron microscopy (TEM) images, revealing a large number of nanoparticles in the plate-like structure of the used catalyst. The heterogeneous structure formed by different components increases the active surface area, which is beneficial for maintaining catalytic activity and may even further enhance it. Therefore, the method of this invention is simple, economical, convenient to operate, and easy to mass-produce, possessing significant potential application value in many industrial catalysts and other disciplines.

Claims

1. Use of a porous sheet-like composite catalyst for catalyzing oxidation of NMST to NMSBA, characterized in that, The preparation method of the porous flaky composite catalyst comprises the following steps: Step 1: terephthalic acid is dissolved in an N,N-dimethylformamide solution, and after ultrasonic dispersion, an A solution is obtained; FeCl3·6H2O is dissolved in an N,N-dimethylformamide solution, and after ultrasonic dispersion, a B solution is obtained; Step 2: the A solution and the B solution are mixed according to a volume ratio of 1:1, and then transferred to a polytetrafluoroethylene lining of a high-pressure reaction kettle; after the high-pressure reaction kettle is closed through a stainless steel jacket, it is placed in an oven for heating; after the reaction in the high-pressure reaction kettle is completed, the oven stops heating; after the high-pressure reaction kettle is cooled to room temperature, the solid-state component obtained after the reaction is taken out from the high-pressure reaction kettle; Step 3: the solid-state component prepared in step 2 is washed with N,N-dimethylformamide and an alcohol solution respectively for multiple times, and then dried, to obtain a MIL-88B(Fe) powder; Step 4: the MIL-88B(Fe) powder prepared in step 3 is placed in an alkali solution for crystallization treatment; after the crystallization treatment is completed, the MIL-88B(Fe) powder is washed with an alcohol solution, and then dried, to obtain a FeOOH / Fe3O4 / MOF composite material, which is a porous flaky composite catalyst with MOF as a template; the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution; the crystallization treatment lasts for 4-12 hours.

2. Use of the porous sheet-like composite catalyst according to claim 1, characterized in that, The concentration of the A solution in step 1 is 0.1-0.5 moL / L, and the concentration of the B solution is 0.1-0.5 moL / L.

3. Use of the porous sheet-like composite catalyst according to claim 1, characterized in that, The temperature of heating in the oven in step 2 is 120-180 DEG C, and the reaction time of the high-pressure reaction kettle in the oven is 12-24 hours.

4. Use of the porous sheet-shaped composite catalyst according to claim 1, characterized in that, The washing times of N,N-dimethylformamide and the alcohol solution in step 3 are both three times.

5. The application of the porous flaky composite catalyst according to claim 1, characterized in that: The alcohol solution in steps 3 and 4 is a methanol solution; The concentration of the alkali solution is 0.15-1 moL / L.

6. Use of a catalytic material for catalyzing oxidation of NMST to NMSBA, the catalytic material comprising glass beads and a catalyst layer attached to the surface of the glass beads, the catalyst layer having a composition of a porous sheet-like composite catalyst, characterized in that, The preparation method of the porous flaky composite catalyst comprises the following steps: Step 1: terephthalic acid is dissolved in an N,N-dimethylformamide solution, and after ultrasonic dispersion, an A solution is obtained; FeCl3·6H2O is dissolved in an N,N-dimethylformamide solution, and after ultrasonic dispersion, a B solution is obtained; Step 2: the A solution and the B solution are mixed according to a volume ratio of 1:1, and then transferred to a polytetrafluoroethylene lining of a high-pressure reaction kettle; after the high-pressure reaction kettle is closed through a stainless steel jacket, it is placed in an oven for heating; after the reaction in the high-pressure reaction kettle is completed, the oven stops heating; after the high-pressure reaction kettle is cooled to room temperature, the solid-state component obtained after the reaction is taken out from the high-pressure reaction kettle; Step 3: the solid-state component prepared in step 2 is washed with N,N-dimethylformamide and an alcohol solution respectively for multiple times, and then dried, to obtain a MIL-88B(Fe) powder; Step 4: the MIL-88B(Fe) powder prepared in step 3 is put into an alkali solution for crystallization treatment, after the crystallization treatment is completed, the MIL-88B(Fe) powder is washed with an alcohol solution and dried to obtain a FeOOH / Fe3O4 / MOF composite material, i.e. a porous flaky composite catalyst with MOF as a template, the alkali solution is a sodium hydroxide or potassium hydroxide solution, and the crystallization treatment lasts for 4-12 hours.

7. Use of a catalytic material according to claim 6, characterised in that The concentration of the A solution in step 1 is 0.1-0.5 moL / L, and the concentration of the B solution is 0.1-0.5 moL / L.

8. Use of a catalytic material according to claim 6, characterised in that, The temperature of heating in the oven in step 2 is 120-180℃, and the reaction time of the high-pressure reaction kettle in the oven is 12-24 hours.

9. Use of a catalytic material according to claim 6, characterised in that, The washing times of the N,N-dimethylformamide and the alcohol solution in step 3 are both three times.

10. The application of the catalytic material according to claim 6, characterized in that: The alcohol solution in step 3 and step 4 is a methanol solution. The concentration of the alkali solution is 0.15-1 moL / L.

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