Method for preparing chitosan intercalation and aluminum-cobalt pillared synergistically-modified montmorillonite palladium-loaded catalyst by one-pot method and application of chitosan intercalation and aluminum-cobalt pillared synergistically-modified montmorillonite palladium-loaded catalyst

Abstract

The invention discloses a method for preparing a chitosan intercalation and aluminum-cobalt pillared synergistically modified montmorillonite palladium-loaded catalyst by a one-pot method and application. The preparation method comprises the following steps: (1) preparing polymerized polyhydroxy aluminum-cobalt binuclear metal cation pillared liquid; (2) carrying out cation exchange on the pillared liquid and montmorillonite; (3) further performing cation exchange with the chitosan solution subjected to amino protonation and performing chemical complexation with palladium ions; and (4) calcining the composite system at medium temperature. According to the invention, the composite pillared agent, polymer and palladium are continuously intercalated into montmorillonite layers through ion exchange or chemical complexation in one pot, and then are calcined at medium temperature in an inert gas atmosphere, so that a multi-step complex route in a traditional preparation process is overcome, and the technical process is more efficient and simplified. Meanwhile, when the catalyst is applied to a Sonogashira organic coupling reaction, the prepared catalyst has the characteristics of good adsorption and diffusion performance, firm loading of nano-palladium particles, good catalytic activity, good reutilization stability and the like.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst material preparation technology, and in particular to a one-pot method for preparing a chitosan intercalation and aluminum-cobalt pillaring synergistically modified montmorillonite palladium-supported catalyst and its application. Background Art

[0002] The palladium metal complex is loaded on a suitable carrier to make a heterogeneous catalyst and used in various organic reactions. It can not only ensure good catalytic activity, but also be easily separated from the reaction system by simple means (filtration, centrifugation, magnetic separation, etc.), thereby realizing the recycling of the catalyst and effectively improving the greenness and economy of the reaction. Among the many candidate carriers of palladium metal, the natural polymer chitosan has received considerable favor. Its molecular skeleton contains a large number of amino and hydroxyl groups, which can form a strong complex with active substances such as palladium metal and its oxide to achieve a firm load. However, the comprehensive performance of chitosan polymer in terms of mechanical strength, porosity, thermal stability, diffusivity, solvent resistance, etc. is limited, and the prepared chitosan-supported palladium catalyst often shows limited catalytic activity and reusability.

[0003] Hybridization of chitosan with other inorganic carriers with good mechanical stability and rich porous structure has been proven to be an effective method to synergistically improve the comprehensive performance of catalytic materials. For example, through ion exchange or hydrogen bond interaction, chitosan molecular chains or chitosan complex palladium complexes can be effectively intercalated into the interlayer space of montmorillonite or pillared montmorillonite with rich layered porous structure, and the excellent complexing ability of polymer chains and the significant physical property advantages of inorganic montmorillonite are efficiently combined. As reported in the literature (ACS Appl. Mater. Interfaces 2016, 8, 33157-33164.), chitosan intercalated montmorillonite-supported palladium catalytic materials have high catalytic activity and reusability in coupling reactions involving iodinated aromatics, but the adsorption performance of the material is limited by the polymer flexible intercalation. Montmorillonite is first modified by inorganic aluminum or aluminum-iron composite pillaring to form stable inorganic "pillars" in the interlayer space of the montmorillonite wafers to effectively support the wafer layers, which can induce a large number of stable micropores / mesoporous structures. Then, chitosan-complexed palladium complexes are introduced between the pillared montmorillonite layers through ion exchange. The specific surface area of the prepared catalytic material can be further greatly improved, and the layered mesoporous structure is also more stable. As reported in the literature (Appl. Clay Sci. 2020, 195, 105721), the prepared catalytic material has a good catalytic effect on coupling reactions involving not only iodoaromatic hydrocarbons but also bromoaromatic hydrocarbons, and the overall performance is significantly improved.

[0004] However, during the modification of montmorillonite by inorganic oxide pillaring, a high-temperature calcination step is necessary. The temperature is generally above 300 °C, which is higher than the decomposition temperature of general polymers. Only in this way can the pillaring agent (polymeric polyhydroxy metal cations) inserted into the interlayer be dehydrated to transform into stable metal oxide pillars. This makes it very difficult to synchronize the inorganic metal oxide pillaring and the organic intercalation modification of chitosan polymers. The conventional strategy is that montmorillonite is generally first subjected to steps such as intercalation, separation, and high-temperature calcination with a polymeric polyhydroxy cation pillaring agent to prepare pillared montmorillonite, and then an organic polymer-palladium complex is introduced into the interlayer space of the pillared montmorillonite through solution ion exchange. Obviously, such a preparation method has disadvantages such as a long synthesis route, complex steps, and cumbersome processes. There are also some works that directly adopt the strategy of abandoning the high-temperature calcination step. For example, Liao et al. reported (Compos. Sci. Technol. 2008, 68, 2917-2921) that a polymeric hydroxyaluminum cation pillaring agent was first dropped into a montmorillonite dispersion for solution intercalation compounding, and then this compound was added to a chitosan solution for further polymer intercalation. The inorganic pillaring agent and the organic polymer composite intercalation modified montmorillonite obtained after centrifugal separation can also be directly used for the adsorption of dye molecules. However, due to the lack of a perfect and stable pillaring structure, the structural parameters such as pore structure and specific surface area have not been effectively improved, and the adsorption and removal effect is limited. At present, there is no literature report on a new one-pot, highly efficient, and simplified process for the "rigid" pillaring of inorganic oxides and the "flexible" intercalation of organic polymers (or polymer-palladium complexes).

[0005] Based on this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a method and application for preparing a palladium-loaded catalyst with chitosan intercalation and aluminum-cobalt pillaring synergistically modified montmorillonite by a one-pot method. A new one-pot process is adopted: first, in a solution state, a composite pillaring agent, a polymer, and palladium are successively intercalated into the montmorillonite interlayer through ion exchange or chemical complexation in one pot, and then, in an inert gas atmosphere, the composite is calcined at a moderate temperature (lower than the polymer decomposition temperature) to form a new catalytic functional material. The entire preparation process avoids the complex route of first inorganic pillaring and then organic polymer modification, and has the advantages of a more simplified and efficient process, and excellent comprehensive performance of the prepared catalytic material.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A method for preparing a palladium-loaded catalyst with chitosan intercalation and aluminum-cobalt pillaring synergistically modified montmorillonite by a one-pot method, comprising the following steps:

[0009] (1) Add sodium hydroxide solution dropwise to the aluminum chloride - cobalt nitrate mixed solution, control the molar ratio of aluminum - cobalt cations to hydroxide ions to reach 1 / 2.4, heat in a water bath and stir, then age the mixed solution to obtain the aluminum - cobalt pillared liquid;

[0010] (2) Add the aluminum - cobalt pillared liquid to the montmorillonite suspension in a certain proportion, heat in a water bath and stir to prepare a polymerized polyhydroxy aluminum - cobalt cation - intercalated montmorillonite suspension for standby;

[0011] (3) Add the chitosan acetate solution to the suspension obtained in step (2) in a certain proportion, heat in a water bath and stir, then continue to add the Na2PdCl4 solution dropwise to the mixed system, stir, centrifuge the suspension, wash it to neutral, and dry to obtain the composite for standby;

[0012] (4) Calcinate the composite obtained in step (3) at 200 °C in an N2 atmosphere, reduce and activate it with ethylene glycol and then dry to obtain a novel palladium - loaded catalyst with chitosan intercalation and aluminum - cobalt pillaring synergistic modification of montmorillonite.

[0013] In step (1), the aluminum chloride - cobalt nitrate mixed solution is prepared by mixing 0.2 mol / L aluminum chloride solution and 0.2 mol / L cobalt nitrate solution at a volume ratio of 7.5 / 1 - 10 / 1; the concentration of the sodium hydroxide solution is 0.4 mol / L. 3. The one - pot preparation method of a palladium - loaded catalyst with chitosan intercalation and aluminum - cobalt pillaring synergistic modification of montmorillonite as claimed in claim 1, wherein: in step (1), the temperature of heating and stirring in the water bath is 60 °C and the time is 3 h; the aging temperature is 60 °C and the time is 12 h.

[0014] In step (1), the temperature of heating and stirring in the water bath is 60 °C and the time is 3 h; the aging temperature is 60 °C and the time is 12 h.

[0015] In step (2), the ratio of aluminum - cobalt cations to montmorillonite in the polymerized polyhydroxy aluminum - cobalt cation - intercalated montmorillonite suspension is 20 mmol / 1 g.

[0016] In step (2), the montmorillonite suspension is prepared according to the ratio of the amount of montmorillonite to distilled water of 2 - 2.5 g:250 mL; the temperature of heating and stirring in the water bath is 60 °C and the stirring time is 6 h.

[0017] In step (3), the chitosan acetate solution is prepared by mixing chitosan with 2 wt% dilute acetic acid at a ratio of 0.3125 - 1.5 g : 50 mL. The mass ratio of the added chitosan to the montmorillonite added in step (2) is 1 / 8 - 3 / 4. The temperature for water bath heating and stirring is 60°C, and the stirring time is 2 h. The Na2PdCl4 solution is prepared by mixing PdCl2, NaCl, and deionized water at a ratio of 0.3 g : 2 g : 100 mL. The dosage ratio of the Na2PdCl4 solution to chitosan is (2 - 5) mL : (0.3125 - 1.5) g.

[0018] In step (4), the temperature for medium-temperature calcination is 200°C, and the calcination time is 12 h.

[0019] Application of a palladium-loaded catalyst based on chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite prepared by a one-pot method, wherein the palladium-loaded catalyst based on chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite is applied to the Sonogashira cross-coupling reaction of haloarenes and terminal alkynes.

[0020] The haloarene, phenylacetylene, potassium acetate, and the palladium-loaded catalyst based on chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite are added to a mixed solvent of mL dimethyl sulfoxide and mL ethylene glycol according to a molar ratio of 1:1.2:2:0.002, and the Sonogashira cross-coupling reaction is carried out in an air atmosphere at 90°C, and the coupling product is obtained by extraction and separation.

[0021] After the Sonogashira cross-coupling reaction is completed, the palladium-loaded catalyst based on chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite is recovered and then continuously applied to the Sonogashira cross-coupling reaction of haloarenes and phenylacetylene or its derivatives.

[0022] The main principle of preparing the catalyst in the present invention is as follows: In the solution state, after polyhydroxy aluminum-cobalt cations are intercalated into montmorillonite, the interlayer space is effectively expanded, and chitosan molecules and palladium ions are more likely to enter the interlayer of montmorillonite. Then, through medium-temperature calcination in an inert gas atmosphere, the polyhydroxy aluminum-cobalt cations can be effectively transformed into stable oxide pillars to form a relatively perfect pillared structure. At the same time, the chitosan-palladium complex can also maintain a stable intercalation in the interlayer. Due to the synergistic effect of the "rigid confinement effect" of this layered montmorillonite pillared structure and the "flexible anchoring effect" of the chitosan molecular chain, during catalytic application, the loss of palladium active components is slow, and the constructed heterogeneous catalytic material has both high catalytic activity and reusability stability.

[0023] The catalyst obtained by using the present invention is applied to the Sonogashira reaction, and the main reaction process is as Figure 1 shown.

[0024] The beneficial effects of the present invention are:

[0025] 1. The one-pot continuous intercalation / complexation and medium-temperature calcination preparation process is simple and efficient, overcoming the multi-step complex route of first preparing stable inorganic pillared montmorillonite by high-temperature calcination and then modifying it by organic polymer intercalation in the traditional preparation process.

[0026] 2. The palladium nanoparticles are small in size and uniformly dispersed, generally less than 2 nm, and mostly dispersed and embedded in the interlayers of the pillared montmorillonite.

[0027] 3. When the prepared catalyst is applied to the Sonogashira reaction, it exhibits excellent comprehensive catalytic performance (good adsorption and diffusion performance, firm loading of nano-palladium particles, excellent catalytic activity and reusability stability, etc.). When the catalyst dosage is as low as 0.2 mol%, it can catalyze the Sonogashira reaction of most haloarenes and terminal alkynes with excellent yields, and can be reused more than 20 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the main reaction process of the catalyst of the present invention applied to the Sonogashira reaction;

[0029] Figure 2 It is an X-ray powder diffraction pattern of the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst prepared in Examples 1-3 of the present invention;

[0030] Figure 3 It is a high-resolution transmission electron microscopy image of the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst prepared in Example 1 of the present invention;

[0031] Figure 4 It is a nitrogen adsorption-desorption isotherm curve of the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst prepared in Examples 1-3 of the present invention;

[0032] Figure 5 It is a reusability performance diagram of the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst prepared in Example 1 of the present invention in the Sonogashira coupling reaction. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be further described below in conjunction with the drawings and specific embodiments:

[0034] Example 1

[0035] (1) Take a certain amount of NaOH, dissolve it in deionized water to prepare a solution with a NaOH concentration of 0.4 mol / L. Take a certain amount of AlCl₃·6H₂O, dissolve it in deionized water to prepare a solution with an AlCl₃ concentration of 0.2 mol / L. Take a certain amount of Co(NO₃)₂·6H₂O, dissolve it in deionized water to prepare a solution with a Co(NO₃)₂ concentration of 0.2 mol / L; Take 150 mL of the AlCl₃ solution and mix it evenly with 20 mL of the Co(NO₃)₂ solution. According to the ratio of n(Al 3+ -Co 2+ ) : n(OH - ) = 1:2.4 (mol) (that is, the ratio of the total molar amount of Al 3+ and Co 2+ to the molar amount of OH - is 1:2.4), add 204 mL of the NaOH solution dropwise to the mixed solution, heat it in a water bath at 60 °C and stir for 3 h, age the mixed solution in an oven at 60 °C for 12 h to obtain an aluminum-cobalt pillared solution;

[0036] (2) Take 2.5 g of MMT and disperse it in 250 mL of distilled water to form a suspension. According to the ratio of (Al 3+ -Co 2+ ) : MMT = 20 mmol : 1 g, add the aluminum-cobalt pillared solution dropwise to the suspension, heat it in a water bath at 60 °C and stir for 6 h to allow the polyhydroxy aluminum-cobalt cations to intercalate into the montmorillonite interlayer;

[0037] (3) Take 0.3125 g of chitosan and dissolve it in 50 mL of 2 wt% dilute acetic acid to form a homogeneous solution. Add the chitosan solution to the above-mentioned polyhydroxy aluminum-cobalt cation intercalated montmorillonite suspension, heat it in a water bath at 60 °C and stir for 2 h to allow the chitosan molecules to effectively intercalate into the montmorillonite interlayer after the polyhydroxy aluminum / cobalt cations are combined; Dissolve 0.3 g of PdCl₂ in 100 mL of deionized water in the presence of 2 g of NaCl to prepare a Na₂PdCl₄ solution. Add 2 mL of the Na₂PdCl₄ solution dropwise to the suspension and stir for 0.5 h to enable Pd 2+ to be loaded through chemical complexation with the interlayer chitosan molecules. Centrifuge and wash with deionized water until neutral, and dry for later use.

[0038] (4) Place the complex obtained in step (3) in a tubular muffle furnace, under a nitrogen atmosphere, calcine it at 200 °C for 12 h. On the one hand, ensure that the calcination temperature is lower than the decomposition temperature of the chitosan macromolecules, and on the other hand, effectively dehydrate the polyhydroxy aluminum-cobalt cations to transform them into aluminum-cobalt oxide pillars; Separate and reduce and activate with ethylene glycol at 80 °C to reduce the loaded Pd 2+ to Pd 0The nanoparticles were dried to obtain a novel palladium-loaded catalyst 1 with chitosan intercalation and synergistic modification of montmorillonite supported by aluminum-cobalt pillars.

[0039] Example 2

[0040] (1) A certain amount of NaOH was dissolved in deionized water to prepare a solution with a NaOH concentration of 0.4 mol / L. A certain amount of AlCl3·6H2O was dissolved in deionized water to prepare a solution with an AlCl3 concentration of 0.2 mol / L. A certain amount of Co(NO3)2·6H2O was dissolved in deionized water to prepare a solution with a Co(NO3)2 concentration of 0.2 mol / L. 150 mL of the AlCl3 solution was mixed with 20 mL of the Co(NO3)2 solution evenly. According to the ratio of n(Al 3+ -Co 2+ ) : n(OH - ) = 1:2.4 (mol) (that is, the ratio of the total molar amount of Al 3+ and Co 2+ to the molar amount of OH - is 1:2.4), 204 mL of the NaOH solution was added dropwise to the mixed solution. It was heated in a water bath at 60°C and stirred for 3 h, and the mixed solution was aged in an oven at 60°C for 12 h to obtain the aluminum-cobalt pillar-supported solution;

[0041] (2) 2 g of MMT was dispersed in 250 mL of distilled water to form a suspension. According to the ratio of (Al 3+ -Co 2+ ) : MMT = 20 mmol : 1 g, the aluminum-cobalt pillar-supported solution was added dropwise to the suspension. It was heated in a water bath at 60°C and stirred for 6 h to allow the polymerized polyhydroxy aluminum-cobalt cations to intercalate into the montmorillonite interlayer;

[0042] (3) 1.5 g of chitosan was dissolved in 50 mL of 2 wt% dilute acetic acid to form a homogeneous solution. The chitosan solution was added to the above-mentioned polymerized polyhydroxy aluminum-cobalt cation intercalated montmorillonite suspension. It was heated in a water bath at 60°C and stirred for 2 h. 0.3 g of PdCl2 was dissolved in 100 mL of deionized water in the presence of 2 g of NaCl to prepare a Na2PdCl4 solution. 5 mL of the Na2PdCl4 solution was added dropwise to the suspension. After stirring for 0.5 h, it was centrifuged, and washed with deionized water by centrifugation until neutral, and then dried for standby.

[0043] (4) The complex obtained in step (3) was placed in a tubular muffle furnace, calcined at 200°C for 12 h under a nitrogen atmosphere, separated, reduced and activated with ethylene glycol at 80°C, and then dried to obtain a novel palladium-loaded catalyst 2 with chitosan intercalation and synergistic modification of montmorillonite supported by aluminum-cobalt pillars.

[0044] Example 3

[0045] (1) Take a certain amount of NaOH, dissolve it in deionized water to prepare a solution with a NaOH concentration of 0.4 mol / L. Take a certain amount of AlCl₃·6H₂O, dissolve it in deionized water to prepare a solution with an AlCl₃ concentration of 0.2 mol / L. Take a certain amount of Co(NO₃)₂·6H₂O, dissolve it in deionized water to prepare a solution with a Co(NO₃)₂ concentration of 0.2 mol / L; Take 150 mL of the AlCl₃ solution and mix it evenly with 15 mL of the Co(NO₃)₂ solution. According to the ratio of n(Al 3+ -Co 2+ ) : n(OH - ) = 1:2.4 (mol), add 198 mL of the NaOH solution dropwise to the mixed solution, heat it in a water bath at 60 °C and stir for 3 h, age the mixed solution in an oven at 60 °C for 12 h to obtain an aluminum-cobalt pillared solution;

[0046] (2) Take 2.5 g of MMT and disperse it in 250 mL of distilled water to form a suspension. According to the ratio of (Al 3+ -Co 2+ ) : MMT = 20 mmol : 1 g (that is, the ratio of the total molar amount of Al 3+ and Co 2+ to the molar amount of OH - is 1:2.4), add the aluminum-cobalt pillared solution dropwise to the suspension, heat it in a water bath at 60 °C and stir for 6 h to allow the polymeric polyhydroxy aluminum cobalt cations to intercalate into the montmorillonite interlayer;

[0047] (3) Take 0.3125 g of chitosan and dissolve it in 50 mL of 2 wt% dilute acetic acid to form a homogeneous solution. Add the chitosan solution to the above-mentioned polymeric polyhydroxy aluminum-cobalt cation intercalated montmorillonite suspension, heat it in a water bath at 60 °C and stir for 2 h. Dissolve 0.3 g of PdCl₂ in 100 mL of deionized water in the presence of 2 g of NaCl to prepare a Na₂PdCl₄ solution. Continue to add 2 mL of the Na₂PdCl₄ solution dropwise to the suspension, stir for 0.5 h, then centrifuge and wash with deionized water by centrifugation until neutral, and dry for later use.

[0048] (4) Place the complex obtained in step (3) in a tubular muffle furnace, under a nitrogen atmosphere, calcine it at 200 °C for 12 h, separate and reduce and activate it with ethylene glycol at 80 °C, and then dry to obtain a novel chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst 3.

[0049] As Figure 2 shown, the X-ray diffraction d 001The peak appears at a 2θ angle of 7.15°. According to the calculation of the Bragg equation, its interlayer spacing is 1.25 nm. The interlayer spacing of the corresponding catalyst 1 is 1.79 nm, that of catalyst 2 is 1.82 nm, and that of catalyst 3 is 1.81 nm. This shows that the main factor affecting the interlayer spacing is the aluminum-cobalt composite pillaring. The intercalation modification of chitosan molecules contributes less to the interlayer spacing of pillared montmorillonite, and its complex with palladium is mainly distributed in the interlayer space of pillared montmorillonite. As Figure 3 shown, the high-resolution transmission electron microscope image of catalyst 1 shows that palladium nanoparticles are uniformly dispersed in the interlayers of montmorillonite co-modified by chitosan intercalation and aluminum-cobalt pillaring, with a size below 2 nm; the ICP results show that the palladium loadings (calculated by Pd 2+ content) in catalysts 1, 2, and 3 are approximately 1.2 wt%, 2.6 wt%, and 1.1 wt% respectively. As Figure 4 shown, the nitrogen adsorption and desorption properties of catalysts 1, 2, and 3 were measured. The measurement results are shown in Table 1. The BET specific surface areas of each catalyst are 59.1 m 2 / g, 43.1 m 2 / g, and 41.5 m 2 / g respectively. Compared with the BET specific surface area data of 11.8 m 2 / g of the montmorillonite raw material, there is a significant increase; moreover, the pore volume of the catalyst has also increased significantly compared to the montmorillonite raw material.

[0050] Table 1 Nitrogen adsorption data of palladium-loaded catalysts based on chitosan intercalated and aluminum-cobalt pillared co-modified montmorillonite prepared in Examples 1-3 of the present invention

[0051] Sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> Montmorillonite raw material 11.8 0.06 Catalyst 1 59.1 0.14 Catalyst 2 43.1 0.11 Catalyst 3 41.5 0.09

[0052] Obviously, for the palladium-loaded catalyst based on chitosan intercalated and aluminum-cobalt pillared co-modified montmorillonite provided in the examples of the present invention, the aluminum-cobalt pillaring agent, chitosan molecules, and the active component palladium successively enter the montmorillonite interlayers through ion exchange or chemical complexation in one pot and then are calcined at medium temperature in an inert gas atmosphere. The physical properties of the catalyst can be achieved by adjusting the ratio of chitosan molecules to montmorillonite, and the content of the active component palladium can also be adjusted by the addition amount of the palladium ion solution.

[0053] Application of palladium-loaded catalyst based on chitosan intercalated and aluminum-cobalt pillared co-modified montmorillonite:

[0054] Application Example 1

[0055] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of iodobenzene and phenylacetylene: Add iodobenzene, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst in a molar ratio of 1:1.2:2:0.002 to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol. n(iodobenzene) is 1 mmol. React at 90 °C in an air atmosphere for 2 h. Extract and separate with ethyl acetate and conduct qualitative and quantitative analysis on the obtained coupling product. The product structure is confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 7.55 - 7.50 (m, 4H), 7.34 - 7.28 (m, 6H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 are comparable. The yields of the coupling product analyzed by GC-MS are 99%, 98%, and 99% respectively.

[0056] Application Example 2

[0057] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of 2-methyl iodobenzene and phenylacetylene: Add 2-methyl iodobenzene, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst in a molar ratio of 1:1.2:2:0.002 to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol. n(2-methyl iodobenzene) is 1 mmol. React at 90 °C in an air atmosphere for 2 h. Extract and separate with ethyl acetate and conduct qualitative and quantitative analysis on the obtained coupling product. The product structure is confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 7.56 - 7.47 (m, 3H), 7.37 - 7.30 (m, 3H), 7.24 - 7.19 (m, 2H), 7.16 (dd, J = 7.7, 4.4 Hz, 1H), 2.50 (s, 3H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 are comparable. The yields of the coupling product analyzed by GC-MS are 90%, 88%, and 86% respectively.

[0058] Application Example 3

[0059] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of 3-iodotoluene and phenylacetylene: 3-iodotoluene, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst were added to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol in a molar ratio of 1:1.2:2:0.002. n(3-iodotoluene) was 1 mmol, and the reaction was carried out at 90 °C in an air atmosphere for 2 h. The reaction mixture was extracted with ethyl acetate, and the obtained coupling product was subjected to qualitative and quantitative analysis. The product structure was confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 7.62-7.55 (m, 2H), 7.45-7.33 (m, 5H), 7.32-7.25 (m, 1H), 7.19 (d, J = 7.6 Hz, 1H), 2.40 (s, 3H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 were comparable. The yields of the coupling product analyzed by GC-MS were 96%, 92%, and 90% respectively.

[0060] Application Example 4

[0061] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of 4-methoxyiodobenzene and phenylacetylene: 4-methoxyiodobenzene, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst were added to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol in a molar ratio of 1:1.2:2:0.002. n(4-methoxyiodobenzene) was 1 mmol, and the reaction was carried out at 90 °C in an air atmosphere for 2 h. The reaction mixture was extracted with ethyl acetate, and the obtained coupling product was subjected to qualitative and quantitative analysis. The product structure was confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 7.66-7.50 (m, 4H), 7.46-7.34 (m, 3H), 6.93 (d, J = 8.8 Hz, 2H), 3.85 (s, 3H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 were comparable. The yields of the coupling product analyzed by GC-MS were 97%, 93%, and 92% respectively.

[0062] Application Example 5

[0063] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of 2-chloroiodobenzene and phenylacetylene: 2-chloroiodobenzene, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst were added to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol in a molar ratio of 1:1.2:2:0.002. n(2-chloroiodobenzene) was 1 mmol, and the reaction was carried out at 90 °C in an air atmosphere for 2 h. Ethyl acetate was used for extraction and separation, and the obtained coupling product was subjected to qualitative and quantitative analysis. The product structure was confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 7.59 - 7.50 (m, 3H), 7.40 - 7.36 (m, 1H), 7.31 (qd, J = 3.7, 1.5 Hz, 3H), 7.23 - 7.15 (m, 2H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 were comparable. The yields of the coupling product analyzed by GC-MS were 91%, 86%, and 85% respectively.

[0064] Application Example 6

[0065] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of 3-chloroiodobenzene and phenylacetylene: 3-chloroiodobenzene, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst were added to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol in a molar ratio of 1:1.2:2:0.002. n(3-chloroiodobenzene) was 1 mmol, and the reaction was carried out at 90 °C in an air atmosphere for 2 h. Ethyl acetate was used for extraction and separation, and the obtained coupling product was subjected to qualitative and quantitative analysis. The product structure was confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 7.55 - 7.47 (m, 3H), 7.38 (dt, J = 7.4, 1.5 Hz, 1H), 7.35 - 7.29 (m, 3H), 7.29 - 7.20 (m, 2H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 were comparable. The yields of the coupling product analyzed by GC-MS were 95%, 90%, and 89% respectively.

[0066] Application Example 7

[0067] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, and Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of bromobenzene and phenylacetylene: Bromobenzene, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst were added to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol in a molar ratio of 1:1.2:2:0.002. n(bromobenzene) was 1 mmol, and the reaction was carried out at 90 °C in an air atmosphere for 2 h. Ethyl acetate was used for extraction and separation, and the obtained coupling product was subjected to qualitative and quantitative analysis. The product structure was confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 7.55 - 7.50 (m, 4H), 7.34 - 7.28 (m, 6H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 were comparable. The yields of the coupling product analyzed by GC-MS were 33%, 32%, and 29% respectively.

[0068] Application Example 8

[0069] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic materials (Catalyst 1, Catalyst 2, and Catalyst 3) prepared in Examples 1-3 as catalysts, for the Sonogashira coupling reaction of p-bromoacetophenone iodobenzene and phenylacetylene: p-Bromoacetophenone, phenylacetylene, potassium acetate, and the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst were added to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol in a molar ratio of 1:1.2:2:0.002. n(p-bromoacetophenone) was 1 mmol, and the reaction was carried out at 90 °C in an air atmosphere for 2 h. Ethyl acetate was used for extraction and separation, and the obtained coupling product was subjected to qualitative and quantitative analysis. The product structure was confirmed by 1 1H NMR spectrum: 1 1H NMR (400 MHz, CDCl3, TMS) δ 8.00 - 7.93 (m, 2H), 7.68 - 7.62 (m, 2H), 7.58 (ddd, J = 5.5, 2.9, 1.6 Hz, 2H), 7.45 - 7.37 (m, 3H), 2.63 (s, 3H); The catalytic activities of Catalyst 1, Catalyst 2, and Catalyst 3 were comparable. The yields of the coupling product analyzed by GC-MS were 83%, 82%, and 82% respectively.

[0070] Application Example 9

[0071] The chitosan intercalation and aluminum-cobalt pillaring synergistically modified montmorillonite palladium catalytic materials (catalyst 1, catalyst 2, catalyst 3) prepared in Examples 1-3 were used as catalysts for the Sonogashira coupling reaction of p-methyl bromobenzene and phenylacetylene: p-methyl bromobenzene, phenylacetylene, potassium acetate, chitosan intercalation and aluminum-cobalt pillaring synergistically modified montmorillonite palladium catalyst were added to a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol in a molar ratio of 1:1.2:2:0.002, n (p-methyl bromobenzene) was 1 mmol, and the reaction was carried out at 90 ° C in an air atmosphere for 2 h, and the obtained coupling product was extracted and separated with ethyl acetate, and the obtained coupling product was qualitatively and quantitatively analyzed. The product structure is shown in FIG. 1 H NMR spectrum confirmed: 1 H NMR (400 MHz, CDCl3, TMS) 7.67-7.62 (m, 2H), 7.58-7.53 (m, 2H), 7.48-7.38 (m, 3H), 7.25 (d, J=7.9 Hz, 2H), 2.46 (s, 3H); The catalytic activities of catalyst 1, catalyst 2 and catalyst 3 are equivalent. The yields of the coupling products were 32%, 30% and 28% respectively according to GC-MS quantitative analysis.

[0072] The above application examples 1-9 show that the three catalysts prepared by using examples 1-3 all exhibit excellent catalytic activity in the Sonogashira coupling reaction of halogenated aromatics and phenylacetylene; for iodinated aromatics, whether it is an electron-bearing substituent or an electron-withdrawing substituent, a reaction yield of more than 85% is achieved; for bromoaromatics, derivatives containing electron-withdrawing substituents on the benzene ring also achieve a reaction yield of more than 80%. In general, the reaction conditions are mild, the reaction temperature is 90°C, the reaction time is 2h, and the catalyst dosage is 0.2mol% of the substrate. Obviously, its catalytic activity, efficiency and green catalytic conditions are better than the prior art, such as "the method for preparing activated carbon-supported nano Pd / Cu catalyst in one pot in situ (Chinese invention patent, authorization announcement number CN106492836 B)", the reaction temperature is 80°C, the reaction time is 12 hours, and it is necessary to add a phosphine ligand with greater toxicity, and the catalyst Pd dosage is 3mol%.

[0073] Cyclic experiment of palladium-supported montmorillonite catalytic material modified by chitosan intercalation and aluminum-cobalt pillaring:

[0074] Using the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalytic material catalyst 1 prepared in Example 1 as the catalyst, and the Sonogashira coupling reaction of iodobenzene and phenylacetylene as the template reaction, the reaction is carried out in an air atmosphere. The reaction solvent is a mixed solvent of 6 mL of dimethyl sulfoxide and 0.5 mL of ethylene glycol. The reaction temperature is 90 °C, n(iodobenzene) is 1 mmol, and n(iodobenzene):n(phenylacetylene):n(potassium acetate):n(catalyst) = 1:1.2:2:0.002. After the reaction, the chitosan intercalated and aluminum-cobalt pillared synergistically modified montmorillonite supported palladium catalyst 1 is filtered, washed 2-3 times with ethanol and dried, and then this catalyst 1 is continued for the next reaction, such as Figure 5 , after the catalyst is reused 20 times, the yield of the coupling product is 74%, which indicates that the catalyst has good reusability. Obviously, under similar conditions, the catalyst provided by the present invention has obvious advantages in terms of reusability. For example, in the method of "in-situ one-pot preparation of activated carbon supported nano Pd / Cu catalyst (Chinese invention patent, authorization publication number CN 106492836 B)", the Pd dosage of the catalyst is 3 mol%, and it can be reused 5 times; in "Preparation and application of palladium catalyst supported by marine biological waste oyster shell" (Chinese invention patent, authorization publication number CN 110743582 B), the Pd dosage of the catalyst is 0.15 mol%, and it can be reused 6 times.

[0075] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a palladium-loaded catalyst with chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite by a one-pot method, which is characterized in that: It includes the following steps: (1) Add sodium hydroxide solution dropwise to the aluminum chloride - cobalt nitrate mixed solution, control the molar ratio of aluminum - cobalt cations to hydroxide ions to reach 1 / 2.4, heat in a water bath and stir, and then age the mixed solution to obtain an aluminum - cobalt pillared liquid; (2) Add the aluminum - cobalt pillared liquid to the montmorillonite suspension in a certain proportion, heat in a water bath and stir to prepare a polyhydroxy aluminum - cobalt cation - intercalated montmorillonite suspension for standby; (3) Add the - chitosan acetate solution to the suspension obtained in step (2) in a certain proportion, heat in a water bath and stir, then continue to add Na2PdCl4 solution dropwise to the mixed system, stir, centrifuge the suspension, wash it to neutrality, and dry to obtain a composite for standby; (4) Calcinate the composite obtained in step (3) at 200 °C in an N2 atmosphere, reduce and activate it with ethylene glycol and then dry it to obtain a novel palladium - loaded catalyst with chitosan intercalation and aluminum - cobalt pillar support synergistic modification of montmorillonite.

2. The method for preparing a palladium-loaded catalyst with chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite by a one-pot method as described in claim 1, characterized in that: In step (1), the aluminum chloride - cobalt nitrate mixed solution is prepared by mixing 0.2 mol / L aluminum chloride solution and 0.2 mol / L cobalt nitrate solution in a volume ratio of 7.5 / 1 - 10 / 1; the concentration of the sodium hydroxide solution is 0.4 mol / L.

3. The one-pot preparation method of a palladium-loaded catalyst modified by chitosan intercalation and aluminum-cobalt pillaring synergistically of montmorillonite as claimed in claim 1, wherein: In step (1), the temperature for heating and stirring in the water bath is 60 °C and the time is 3 h; the aging temperature is 60 °C and the time is 12 h.

4. The method for preparing a palladium-loaded catalyst with chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite by a one-pot method according to claim 1, characterized in that: In step (2), the ratio of aluminum - cobalt cations to montmorillonite in the polyhydroxy aluminum - cobalt cation - intercalated montmorillonite suspension is 20 mmol / 1 g.

5. The method for preparing a palladium-loaded catalyst with chitosan intercalation and aluminum-cobalt pillared synergistic modification of montmorillonite by a one-pot method according to claim 1, characterized in that: In step (2), the montmorillonite suspension is prepared according to the ratio of montmorillonite to distilled water usage of 2 - 2.5 g:250 mL; the temperature for heating and stirring in the water bath is 60 °C and the stirring time is 6 h.

6. For the method of preparing a palladium - loaded catalyst with chitosan intercalation and aluminum - cobalt pillar support synergistic modification of montmorillonite by one - pot method as described in claim 1, in step (3), the chitosan acetate solution is prepared by mixing chitosan 2wt% dilute acetic acid in a usage ratio of 0.3125 - 1.5 g:50 mL, and the mass ratio of the added chitosan to the montmorillonite added in step (2) is 1 / 8 - 3 / 4; the temperature for heating and stirring in the water bath is 60 °C and the stirring time is 2 h; the Na2PdCl4 solution is prepared by mixing PdCl2, NaCl, and deionized water in a usage ratio of 0.3 g:2 g:100 mL, and the usage ratio of the Na2PdCl4 solution to chitosan is (2 - 5) mL:(0.3125 - 1.5) g.

7. For the method of preparing a palladium - loaded catalyst with chitosan intercalation and aluminum - cobalt pillar support synergistic modification of montmorillonite by one - pot method as described in claim 1, in step (4), the temperature for medium - temperature calcination is 200 °C and the calcination time is 12 h.

8. Use of a palladium-loaded catalyst based on chitosan intercalation and aluminum-cobalt pillared clay modified by synergistic modification, prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The palladium - loaded catalyst with chitosan intercalation and aluminum - cobalt pillar support synergistic modification of montmorillonite is applied to the Sonogashira cross - coupling reaction of haloarenes and terminal alkynes.

9. The application of a palladium-loaded catalyst modified by chitosan intercalation and aluminum-cobalt pillaring synergistically of montmorillonite as claimed in claim 8, wherein: A palladium-loaded catalyst modified by chitosan intercalation and aluminum-cobalt pillaring of montmorillonite, together with halogenated aromatic hydrocarbons, phenylacetylene, potassium acetate, was added to a mixed solvent of mL dimethyl sulfoxide and mL ethylene glycol in a molar ratio of 1:1.2:2:0.002, and a Sonogashira cross-coupling reaction was carried out in an air atmosphere at 90 °C. The coupling product was obtained by extraction and separation.

10. Use of a palladium-loaded catalyst modified by chitosan intercalation and aluminum-cobalt pillaring synergistically modified montmorillonite as described in claim 8, characterized in that: After the Sonogashira cross-coupling reaction was completed, the palladium-loaded catalyst modified by chitosan intercalation and aluminum-cobalt pillaring of montmorillonite was recovered and continued to be applied to the Sonogashira cross-coupling reaction of halogenated aromatic hydrocarbons with phenylacetylene or its derivatives.

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