Preparation method and application of modified titanium dioxide catalyst

Abstract

The embodiment of the invention provides a preparation method and application of a modified titanium dioxide catalyst, and the preparation method comprises the following steps: S1, dissolving a titanium source and an organic ligand in a solvent, and adopting a hydrothermal synthesis method to obtain a titanium-based MOF skeleton; and S2, calcining the titanium-based MOF framework in an air atmosphere, and cooling to obtain the modified titanium dioxide catalyst. The invention relates to the field of photocatalytic material preparation. A traditional TiO2-based photocatalyst still faces the problems of low specific surface area, insufficient active sites, easy agglomeration of metal load and the like in CO2 reduction application, and the catalytic efficiency of the traditional TiO2-based photocatalyst is limited. NH2-MIL-125 (Ti) is taken as a precursor, a three-dimensional ordered mesoporous structure of MOF can be inherited through pyrolysis, the obtained TiO2 has a high specific surface area and abundant mass transfer channels, and the separation efficiency and surface reaction activity of photon-generated carriers are remarkably improved. By means of the design, the problem that in a traditional method, metal dispersity is poor is solved, and a new thought is provided for efficient photocatalytic CO2 reduction through structure-performance collaborative optimization.

Description

Technical Field

[0001] The present invention relates to the field of preparation of photocatalytic materials, and specifically refers to a preparation method and application of a modified titanium dioxide catalyst. Background Art

[0002] With the rapid development of industrialization and urbanization, the excessive combustion of traditional fossil fuels has led to a continuous increase in the emissions of greenhouse gases such as carbon dioxide (CO2), triggering a series of environmental problems such as global warming and glacier melting. In order to address the damage to the ecological environment caused by fossil fuel dependence and greenhouse gas emissions, CO2 is converted into economically valuable chemicals (such as carbon monoxide, methane or methanol) through catalytic conversion technology. Among many CO2 conversion technologies, photocatalytic reduction has become a research hotspot because it uses solar energy as the driving force and has advantages such as cleanliness, sustainability, and wide distribution. However, the efficiency of photocatalytic reduction of CO2 is limited by the performance of the catalyst, and the development of catalytic nanomaterials with high activity, high selectivity and high cost-effectiveness has become a key challenge in the current technical field.

[0003] Currently, a variety of catalytic materials have been used in the study of CO2 photocatalytic reduction. Among them, titanium dioxide (TiO2) is widely used in the field of photocatalysis due to its high chemical stability, corrosion resistance, low cost, light resistance in solution and non-toxicity. However, the photocatalytic performance of TiO2 is restricted by its inherent defects, which are mainly manifested as: (1) its relatively wide band gap (about 3.2 eV) results in its ability to absorb only ultraviolet light, limiting the utilization rate of visible light; (2) the rapid recombination of photo-generated electrons and holes reduces the quantum efficiency. To overcome these limitations, researchers have tried to improve its catalytic performance by broadening the spectral absorption range of TiO2 and promoting the separation and transfer of photo-generated carriers. Existing studies have shown that catalysts with high porosity and high specific surface area can significantly increase the active sites and promote the adsorption and activation of reactants (such as CO2 and water). In addition, by doping co-catalysts (such as metal or non-metal species), additional reaction sites can be effectively provided and used as trapping centers for photo-generated electrons or holes, thereby inhibiting carrier recombination and improving the photocatalytic efficiency.

[0004] Although the above methods have made certain progress in improving the photocatalytic performance of TiO2, the existing technologies still have problems such as complex catalyst preparation processes, uneven distribution of active sites, and low catalytic efficiency. Therefore, there is an urgent need to develop a new type of TiO2-based photocatalyst with a simple preparation method, controllable structure and excellent performance to further promote the practical application of CO2 photocatalytic reduction technology. Summary of the Invention

[0005] According to an embodiment of the present invention, a preparation method and application of a modified titanium dioxide catalyst are provided. It is used to solve the technical problems existing in the above background art.

[0006] In the first aspect of the present invention, a method for preparing a modified titanium dioxide catalyst is provided.

[0007] The method for preparing the modified titanium dioxide catalyst comprises the following steps:

[0008] S1: Dissolve a titanium source and an organic ligand in a solvent, and obtain a titanium-based MOF framework by a hydrothermal synthesis method;

[0009] S2: Calcinate the titanium-based MOF framework in an air atmosphere, and obtain a modified titanium dioxide catalyst after cooling.

[0010] Preferably, S101: Disperse the titanium-based MOF framework in a solvent, add a copper salt solution for impregnation, stir and then dry to obtain a copper-containing precursor.

[0011] Preferably, in step S2, the titanium-based MOF framework is calcined to obtain a cake-shaped nano titanium dioxide catalyst.

[0012] Preferably, in step S2, the copper-containing precursor is calcined to obtain a copper-based cake-shaped nano titanium dioxide catalyst.

[0013] Preferably, in step S3, the calcination temperature is 450 °C, the calcination time is 2 h, the heating rate is 2 °C per minute, and it is naturally cooled to below 60 °C. The solvent used for impregnation in step S1 is a mixed solvent of water and anhydrous methanol. The copper-titanium molar ratio of the titanium-based MOF framework in step S1 is 1:200 to 1:50. The copper-containing precursor is calcined in an air atmosphere at 300 - 500 °C for 0.5 - 4 h. The reaction temperature of the hydrothermal synthesis in step S1 is 150 °C and the reaction time is 24 h.

[0014] Preferably, the titanium-based MOF framework in step S1 is NH2-MIL-125(Ti), and the copper salt solution is a copper chloride solution.

[0015] Preferably, a calcination device is used to calcine the titanium-based MOF framework in step S2, which includes a machine shell, a control unit, a door body, a locking mechanism, a heating port, and an auxiliary mechanism. The heating port is arranged on the machine shell. The door body faces the heating port. The door body is connected to the machine shell. The door body is connected to the machine shell through the locking mechanism;

[0016] The auxiliary mechanism includes a box body, a receiving groove, a first stop block, a second stop block, a filter screen, a cover body, a back plate, a rod body, and a magnetic block;

[0017] A filter is detachably connected to the top of the cover body, the bottom of the cover body is fitted with the top of the box body, the accommodating groove is processed on the box body, and a first stopper and a second stopper are respectively connected to the side of the box body away from the door body and the side close to the door body, the cover body is connected to the back plate, the back plate is connected to the rod body, the rod body is slidably connected to the second stopper, and the end of the rod body close to the second stopper is connected to the magnetic block.

[0018] Preferably, the calcining device further comprises a driving mechanism and a supporting mechanism;

[0019] The support mechanism includes two annular grooves, two annular plates, two arc-shaped plates, a plurality of clamping blocks and connecting rods;

[0020] The two annular plates are connected to the cover body, the two annular grooves are respectively processed on the two annular plates, the plurality of clamping blocks are respectively slidably connected to the two annular grooves, the plurality of clamping blocks are respectively connected to the two arc-shaped plates, the two arc-shaped plates are connected by a connecting rod, and the two arc-shaped plates are connected to the housing;

[0021] The driving mechanism comprises a motor, a gear, a first gear ring, a second gear ring, a connecting shaft, a fan blade and a cover;

[0022] The motor is connected to the casing, the output end of the motor is connected to the gear, the gear is meshingly connected to the first gear ring, the inner side of the first gear ring is meshingly connected to the second gear ring, the second gear ring is connected to the connecting shaft, the connecting shaft is rotatably connected to the cover body, the cover body is connected to the casing, the connecting shaft is connected to the fan blades, and the fan blades are arranged in the cover body.

[0023] Preferably, it also includes a moving mechanism; the moving mechanism includes a convex block, a baffle, a hand wheel, two limit rods, a screw, a moving platform, a mounting shaft, a round sleeve, a shifting block and a torsion spring;

[0024] The protrusion is connected to the bottom of the box body, and the shift block can shift the protrusion to move, and the shift block is connected to the round sleeve, and the round sleeve is rotatably connected to the mounting shaft, the torsion spring sleeve is arranged on the mounting shaft, and the two ends of the torsion spring are respectively connected to one side of the round sleeve and the mounting shaft, and the mounting shaft is connected to the moving platform, and the moving platform is threadedly connected to the screw, and the moving platform is slidably connected to the two limit rods, and the two ends of the two limit rods are respectively connected to the baffle and the casing, and the two sides of the screw are respectively rotatably connected to the baffle and the casing, and the side of the screw close to the door body is connected to the hand wheel, and the baffle is connected to the arc plate.

[0025] In the second aspect of the present invention, a use of a modified titanium dioxide catalyst is provided.

[0026] The catalyst has a hierarchical porous structure and highly dispersed copper active sites, and is used to catalyze the CO2 reduction reaction under simulated sunlight irradiation.

[0027] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0028] 1. A preparation method and application of a modified titanium dioxide catalyst provided by the present invention. Traditional TiO2-based photocatalysts still face problems such as low specific surface area, insufficient active sites, and easy agglomeration of metal loading in CO2 reduction applications, which limit their catalytic efficiency. Pyrolysis using NH2-MIL-125(Ti) as a precursor can inherit the three-dimensional ordered mesoporous structure of MOF. The obtained TiO2 has a high specific surface area and rich mass transfer channels, significantly improving the separation efficiency of photogenerated carriers and surface reaction activity. Further, by the strategy of in-situ loading and pyrolysis of Cu on MOF, the sintering of Cu species can be effectively inhibited, realizing its highly dispersed distribution on the TiO2 support. At the same time, Cu-TiO2 interfacial active sites are formed, synergistically promoting the adsorption and activation of CO2. This design not only solves the problem of poor metal dispersion in traditional methods but also provides new ideas for efficient photocatalytic CO2 reduction through structure-performance synergistic optimization.

[0029] It should be understood that the content described in the invention content section is not intended to limit the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Combined with the drawings and referring to the following detailed description, the above and other features, advantages, and aspects of the embodiments of the present invention will become more obvious. In the drawings, the same or similar reference numerals represent the same or similar elements, where:

[0031] Figure 1 Shows the X-ray diffraction patterns of the samples of Example 1 and Example 2 of the preparation method of the modified titanium dioxide catalyst according to the present invention;

[0032] Figure 2 Shows the ultraviolet Raman spectra of the samples of Example 1 and Example 2 of the preparation method of the modified titanium dioxide catalyst according to the present invention and the sample of Comparative Example 1;

[0033] Figure 3 Shows the N2 physical adsorption-desorption diagrams of the samples of Example 1 and Example 2 of the preparation method of the modified titanium dioxide catalyst according to the present invention;

[0034] Figure 4Figure 1 shows SEM images of Samples of Example 1 and Example 2 of the preparation method of the modified titanium dioxide catalyst according to the present invention;

[0035] Figure 5 Figure 2 shows TEM images of the sample of Example 2 of the preparation method of the modified titanium dioxide catalyst according to the present invention;

[0036] Figure 6 Figure 3 shows photocatalytic CO2 reduction performance graphs of the samples of Example 1 and Example 2 and Comparative Example 1 and Comparative Example 2 of the preparation method of the modified titanium dioxide catalyst according to the present invention;

[0037] Figure 7 Figure 4 shows a schematic three-dimensional connection structure diagram of the calcination device according to an embodiment of the present invention;

[0038] Figure 8 Figure 5 shows an exploded view of the calcination device according to an embodiment of the present invention;

[0039] Figure 9 Figure 6 shows a schematic connection structure diagram of the casing, control unit and door body of the calcination device according to an embodiment of the present invention;

[0040] Figure 10 Figure 7 shows a schematic connection structure diagram of the drive mechanism of the calcination device according to an embodiment of the present invention;

[0041] Figure 11 Figure 8 shows a partial cross-sectional view taken along line A-A of the calcination device according to an embodiment of the present invention;

[0042] Figure 12 Figure 9 shows an exploded view of the auxiliary mechanism and the support mechanism of the calcination device according to an embodiment of the present invention;

[0043] Figure 13 Figure 10 shows a schematic connection structure diagram of the auxiliary mechanism of the calcination device according to an embodiment of the present invention;

[0044] Figure 14 Figure 11 shows a partially enlarged view of the drive mechanism of the calcination device according to an embodiment of the present invention;

[0045] Figure 15 Figure 12 shows a schematic connection structure diagram of the gear, the first gear ring and the second gear ring of the calcination device according to an embodiment of the present invention;

[0046] Figure 16 Figure 13 shows a partially enlarged view of the support mechanism of the calcination device according to an embodiment of the present invention;

[0047] Figure 17 Figure 14 shows a schematic connection structure diagram of the support mechanism of the calcination device according to an embodiment of the present invention;

[0048] Figure 18 The schematic connection structure diagram of the moving mechanism of the calcination device according to an embodiment of the present invention is shown.

[0049] The reference numerals are as follows:

[0050] 1 - housing, 2 - control unit, 3 - door body, 4 - locking mechanism, 5 - heating port, 6 - auxiliary mechanism, 601 - box body, 602 - first stopper, 603 - receiving groove, 604 - filter screen, 605 - cover body, 606 - back plate, 607 - rod body, 608 - magnet, 609 - second stopper, 7 - driving mechanism, 701 - motor, 702 - gear, 703 - first gear ring, 704 - second gear ring, 705 - cover body, 706 - connecting shaft, 707 - fan blade, 8 - support mechanism, 801 - annular groove, 802 - annular plate, 803 - arc plate, 804 - clamping block, 805 - connecting rod, 9 - moving mechanism, 901 - convex block, 902 - baffle, 903 - hand wheel, 904 - limiting rod, 905 - screw rod, 906 - moving table, 907 - dial block, 908 - round sleeve, 909 - mounting shaft, 910 - torsion spring. Specific embodiments

[0051] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] In addition, the term "and / or" in this article is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0053] As Figures 1 to 6 shown:

[0054] Embodiment 1:

[0055] Yellow NH2-MIL-125(Ti) was prepared by the hydrothermal method at 150 °C. It was placed in a muffle furnace and heated to 450 °C at a heating rate of 2 °C per minute, calcined at a high temperature for 2 h, and naturally cooled to below 60 °C to end the calcination, obtaining a white solid powder (i.e., a cake-like nano-titanium dioxide catalyst).

[0056] Embodiment 2:

[0057] Yellow NH2-MIL-125(Ti) was prepared by hydrothermal method at 150 °C. The prepared NH2-MIL-125(Ti) was dispersed in a mixed solvent of deionized water and anhydrous methanol and stirred evenly. Then CuCl2 solution was added dropwise. The mixture was stirred on a heating stirrer at 60 °C until the solvent completely evaporated, dried in a vacuum oven at 80 °C for 2 h, and ground evenly to obtain a copper-containing titanium dioxide precursor. The prepared copper-containing titanium dioxide precursor was placed in a muffle furnace and heated to 450 °C at a heating rate of 2 °C per minute, calcined at high temperature for 2 h, and naturally cooled to below 60 °C to end the calcination, obtaining a gray-green solid powder (i.e., copper-based disc-shaped nano-titanium dioxide catalyst).

[0058] Example 3:

[0059] Yellow NH2-MIL-125(Ti) was prepared by hydrothermal method at 150 °C. The prepared NH2-MIL-125(Ti) was dispersed in a mixed solvent of deionized water and anhydrous methanol and stirred evenly. Then CuCl2 solution was added dropwise. The mixture was stirred on a heating stirrer at 60 °C until the solvent completely evaporated, dried in a vacuum oven at 80 °C for 2 h, and ground evenly to obtain a copper-containing titanium dioxide precursor. The prepared copper-containing titanium dioxide precursor was placed in a muffle furnace and heated to 300 °C at a heating rate of 2 °C per minute, calcined at high temperature for 2 h, and naturally cooled to below 60 °C to end the calcination, obtaining a gray-green solid powder (i.e., copper-based disc-shaped nano-titanium dioxide catalyst).

[0060] Example 4:

[0061] Yellow NH2-MIL-125(Ti) was prepared by hydrothermal method at 150 °C. The prepared NH2-MIL-125(Ti) was dispersed in a mixed solvent of deionized water and anhydrous methanol and stirred evenly. Then CuCl2 solution was added dropwise. The mixture was stirred on a heating stirrer at 60 °C until the solvent completely evaporated, dried in a vacuum oven at 80 °C for 2 h, and ground evenly to obtain a copper-containing titanium dioxide precursor. The prepared copper-containing titanium dioxide precursor was placed in a muffle furnace and heated to 500 °C at a heating rate of 2 °C per minute, calcined at high temperature for 2 h, and naturally cooled to below 60 °C to end the calcination, obtaining a gray-green solid powder (i.e., copper-based disc-shaped nano-titanium dioxide catalyst).

[0062] Example 5:

[0063] Yellow NH2-MIL-125(Ti) was prepared by hydrothermal method at 150 °C. The prepared NH2-MIL-125(Ti) was dispersed in a mixed solvent of deionized water and anhydrous methanol and stirred evenly. Then CuCl2 solution was added dropwise. The mixture was stirred on a heating stirrer at 60 °C until the solvent was completely evaporated, dried in a vacuum oven at 80 °C for 2 h, and ground evenly to obtain a copper-containing titanium dioxide precursor. The prepared copper-containing titanium dioxide precursor was placed in a muffle furnace and heated to 500 °C at a heating rate of 10 °C per minute, calcined at high temperature for 4 h, and naturally cooled to below 60 °C to end the calcination, obtaining a gray-green solid powder (i.e., copper-based disk-shaped nano-titanium dioxide catalyst).

[0064] Example 6:

[0065] Yellow NH2-MIL-125(Ti) was prepared by hydrothermal method at 150 °C. The prepared NH2-MIL-125(Ti) was dispersed in a mixed solvent of deionized water and anhydrous methanol and stirred evenly. Then CuCl2 solution was added dropwise. The mixture was stirred on a heating stirrer at 60 °C until the solvent was completely evaporated, dried in a vacuum oven at 80 °C for 2 h, and ground evenly to obtain a copper-containing titanium dioxide precursor. The prepared copper-containing titanium dioxide precursor was placed in a muffle furnace and heated to 500 °C at a heating rate of 4 °C per minute, calcined at high temperature for 0.5 h, and naturally cooled to below 60 °C to end the calcination, obtaining a gray-green solid powder (i.e., copper-based disk-shaped nano-titanium dioxide catalyst).

[0066] Control Example 1

[0067] This comparative example is commercial anatase titanium dioxide.

[0068] Control Example 2

[0069] Copper ions (Cu 2+ ) were loaded onto commercial anatase titanium dioxide by impregnation method to obtain a light green solid powder.

[0070] Description Drawings Figure 1 XRD patterns of the samples prepared in Examples 1 and 2 are shown. It can be seen that only the X-ray diffraction peaks of anatase titanium dioxide exist. The main peaks at 25.4°, 36.9°, 37.8°, 38.6°, 48.2°, 54.1°, 55.2°, 62.9°, 69.0°, 70.5° and 75.4° correspond to the (101), (103), (004), (112), (200), (105), (211), (204), (116), (220) and (215) crystal planes of anatase titanium dioxide respectively. It can be known that the crystal form of titanium dioxide obtained by this preparation method is anatase titanium dioxide, and no characteristic diffraction peak of Cu is observed, which is attributed to the highly dispersed state of Cu in the TiO2 support or the low Cu content.

[0071] Attached drawings of the specification Figure 2 Figure 2 is the ultraviolet Raman spectrum of the samples prepared in Example 1, Example 2 and Comparative Example 1. It can be seen that the signal peaks of anatase titanium dioxide exist in the synthesized materials, and the main peak positions are the same as those of commercial anatase titanium dioxide, which is consistent with the conclusion obtained from the XRD pattern.

[0072] Attached drawings of the specification Figure 3 Figure 3 is the N2 physical adsorption-desorption isotherm of the samples prepared in Example 1 and Example 2. It shows typical type IV isotherm characteristics, and the presence of H3-type hysteresis loop confirms the formation of a three-dimensional hierarchical mesoporous structure in the material. It should be noted that the template precursor MOF, as a metal-organic framework, inherently has microporous characteristics. After pyrolysis at 450 °C, its derivatives retain some of the original pore frameworks while the coordination bonds break and the organic ligands are removed, resulting in a skeleton contraction effect that induces the generation of secondary mesoporous structures with pore sizes distributed between 3 - 8 nm. At the same time, Cu has a kinetic inhibitory effect on the grain boundary migration of titanium dioxide, further promoting the formation of the hierarchical mesoporous structure in the material. This hierarchical mesoporous network not only enhances the diffusion kinetics of CO2 molecules, but its rich mesoporous surface also provides high-density active sites for the adsorption-activation of reaction intermediates.

[0073] Attached drawings of the specification Figure 4 Figure 4 is the SEM image of the samples prepared in Example 1 and Example 2. It can be seen that TiO2 well retains the disc-like structure of MOF.

[0074] Attached drawings of the specification Figure 5 Figure 5 is the TEM image of the sample prepared in Example 2. It can be seen that these disc-like structures are composed of many nanocrystals, and the lattice fringes with spacings of 0.35 and 0.24 nm belong to the (101) crystal plane and (001) crystal plane of anatase titanium dioxide. TEM-Mapping proves that Cu is evenly dispersed on TiO2. The above results show that through the pyrolysis of the Cu / MOF precursor, a copper-based disc-like nano-titanium dioxide catalyst with highly dispersed copper is synthesized.

[0075] It should be noted that the preparation method has the following beneficial effects:

[0076] Excellent catalytic performance: Through the MOF template confinement effect, the highly dispersed and nano-scale stability of copper species in the titanium dioxide support are achieved. Combined with the design of the disc-like three-dimensional mesoporous structure, the specific surface area and active site density of the catalyst are significantly increased. In the photocatalytic CO2 reduction reaction, the catalyst's performance for CO generation is improved by 2 - 3 times, showing excellent selectivity and catalytic efficiency. Among them, the copper-titanium molar ratio of the titanium-based MOF skeleton is 1:200 - 1:50.

[0077] Precise morphology control: Using titanium-containing MOF as a template precursor, disk-shaped titanium dioxide with a three-dimensional mesoporous structure is prepared through an in-situ pyrolysis process, overcoming the defects of traditional TiO2 with a narrow spectral absorption range and a high recombination rate of photo-generated carriers, effectively broadening the light absorption range and promoting the separation and transfer of electrons and holes.

[0078] Green and environmentally friendly reaction system: The catalytic reaction uses water as a solvent without the need for additional sacrificial agents. The process is clean and environmentally friendly, meeting the requirements of sustainable development, and is applicable to the fields of artificial photosynthesis and carbon cycle utilization.

[0079] Simple and controllable preparation process: A preparation method combining hydrothermal synthesis, wet chemistry method and pyrolysis method is adopted. The process is simple, the conditions are easy to control, and the repeatability is high, with good potential for large-scale production.

[0080] In summary, through structural optimization and process innovation, the present invention prepares a copper-based disk-shaped nano-titanium dioxide catalyst with excellent performance and high stability, providing a new material system for the efficient application of photocatalytic CO2 reduction technology, and having important application value in the fields of low-carbon energy conversion and environmental protection.

[0081] Such as Figures 7 to 18As shown, a calcination device is used to calcine the titanium-based MOF framework in step S2. The device includes a casing 1, a control unit 2, a door body 3, a locking mechanism 4, a heating port 5, and an auxiliary mechanism 6. The casing 1 is the main structure of the calcination device and is used to accommodate the titanium-based MOF framework to be calcined. The specific operation method is as follows: The prepared raw materials are placed in a muffle furnace and heated to a fixed temperature at a specified heating rate. After high-temperature calcination, it is naturally cooled to below 60 degrees to end the calcination. The control unit 2, the casing 1, and the heating port 5 form an existing muffle furnace. The user can set the calcination temperature through the control unit 2. The specific internal composition is well-known in the prior art and will not be elaborated here. The heating port 5 is provided on the side wall of the casing 1 and is used to provide heat source for the calcination operation. The door body 3 is arranged opposite to the heating port 5 and is connected to the casing 1 through a hinge or other rotatable connection means to realize the opening and closing of the heating port 5. The locking mechanism 4 is arranged between the door body 3 and the casing 1 and is used to firmly lock the door body 3 on the casing 1 when the door body 3 is closed to ensure the sealing and safety during the calcination process. The control unit 2 is electrically connected to the heating port 5 and the locking mechanism 4 and is used to control the calcination temperature, time, and the opening and closing state of the locking mechanism 4. The auxiliary mechanism 6 is arranged inside the casing 1 and is used to carry and fix the titanium-based MOF framework and assist in completing the material management during the calcination process. The auxiliary mechanism 6 includes a box body 601, a receiving groove 603, a first stopper 602, a second stopper 609, a filter screen 604, a cover body 605, a back plate 606, a rod body 607, and a magnet 608. The structures and functions of each component are described in detail below: The box body 601 is a rectangular or cylindrical container made of a high-temperature resistant material (such as stainless steel or ceramic) and is used to carry the titanium-based MOF framework in step S2. The receiving groove 603 is processed on the top of the box body 601 and is in the form of a groove structure with an upward opening and is used to receive the titanium-based MOF framework. The first stopper 602 and the second stopper 609 are respectively fixed on the outer side wall of the box body 601. The first stopper 602 is located on the side of the box body 601 away from the door body 3, and the second stopper 609 is located on the side close to the door body 3. The two stoppers are made of a high-temperature resistant metal material and can be attracted by a magnetic material and extend along the width direction of the box body 601 to limit the moving range of the box body 601 in the casing 1 and prevent it from being displaced due to vibration or thermal expansion during the calcination process. The cover body 605 is in the form of a flat plate or a structure with a chamber and is made of a high-temperature resistant material with certain mechanical strength (such as heat-resistant alloy). The bottom of the cover body 605 is closely attached to the top of the box body 601 to close the receiving groove 603 and prevent the titanium-based MOF framework from being scattered due to air flow disturbance during the calcination process. The filter screen 604 is detachably connected above the cover body 605 and is preferably fixed by a snap or threaded connection method.The filter screen 604 is made of a high-temperature resistant porous material (such as ceramic fiber or metal mesh). The filter screen 604 is a sintered stainless steel filter screen, which is made by high-temperature vacuum sintering of multiple layers of stainless steel (such as 316L, 304) woven mesh or powder, and has high mechanical strength, corrosion resistance and high-temperature resistance (up to 600 degrees at most, and can be higher with special alloys). The pore size range is usually 1-200 microns, which can effectively intercept powder particles while maintaining good air permeability, and can prevent powder particles from leaking out of the filter screen 604. The back plate 606 is fixed to the side of the cover 605 and forms an integral body with the cover 605 by welding or bolt connection. One end of the rod 607 is fixedly connected to the back plate 606, and the other end extends towards the second stop block 609 and forms a sliding connection with the second stop block 609. The number of the rods 607 is two. Setting two rods 607 can ensure that the box body 601 moves along a straight line. The magnet 608 is fixed to the end of the rod 607 close to the second stop block 609. The magnet 608 can be attached to the second stop block 609 or the first stop block 602 made of metal material for positioning. When the magnet 608 is attracted to the second stop block 609, it represents the farthest distance of the box body 601 relative to the cover 605 at this time. When the magnet 608 is attracted to the first stop block 602, it represents that the cover 605 and the box body 601 are completely fitted. The sizes of the cover 605 and the box body 601 are the same, and the powder in the box body 601 will not be discharged from the gap between the two after they are completely fitted. The cover 605 and other structures are arranged at a position protruding from the heating port 5, and the door body 3 can close the cover 605 and other structures when closed.

[0082] During actual use, the operator sets the calcination temperature and time parameters through the control unit 2, then opens the filter screen 604, places the material into the receiving groove 603 in the box body 601. At this time, the magnet 608 is attracted to the first stop block 602, and then the user pushes the box body 601 so that the box body 601 moves into the heating port 5. At this time, the magnet 608 is attracted to the second stop block 609. After the placement is completed, calcination is carried out. After the calcination is completed, natural heat dissipation is carried out first. Since the internal structure (such as pore structure, crystal morphology or chemical bond) of the titanium-based MOF (metal-organic framework) skeleton has changed significantly after high-temperature calcination, forming the target oxide or porous material (such as TiO2-based porous material). Rapid cooling (such as through forced cooling) may cause thermal stress inside the material, because inconsistent cooling rates in different parts will cause shrinkage differences, thus triggering microcracks or structural defects. 60 degrees is a relatively safe low-temperature threshold. When the temperature is lower than this temperature, the thermal expansion coefficient of the material changes little, the internal stress is basically dissipated, and the structural stability is guaranteed. After the temperature is reduced below 60 degrees, the user takes out the material in the receiving groove 603 under the condition of ensuring safety, and completes the calcination process.

[0083] In this embodiment, the calcination device further includes a support mechanism 8. The support mechanism 8 includes two annular grooves 801, two annular plates 802, two arc-shaped plates 803, a plurality of clamping blocks 804, and a connecting rod 805. The two annular plates 802 are fixed to the side of the cover body 605 by bolts or welding. The two annular grooves 801 are respectively machined on the inner surfaces of the two annular plates 802 and are in the structure of annular grooves. A plurality of clamping blocks 804 are respectively slidably connected to the two annular grooves 801. The number of clamping blocks 804 on each arc-shaped plate 803 is at least 3, which can ensure the normal support of the annular plate 802. The shape of each clamping block 804 is adapted to the cross-section of the annular groove 801 to ensure the stability during the sliding process. A plurality of clamping blocks 804 are respectively fixed to the outer sides of the two arc-shaped plates 803. The two arc-shaped plates 803 are connected to each other by a connecting rod 805. The connecting rod 805 is made of a high-temperature resistant material and is used to enhance the rigidity between the two arc-shaped plates 803. The two arc-shaped plates 803 are fixedly connected to the inner wall of the casing 1 by bolts or buckles to provide stable support for the cover body 605 during the calcination process.

[0084] The calcination device further includes a driving mechanism 7. The driving mechanism 7 includes a motor 701, a gear 702, a first gear ring 703, a second gear ring 704, a connecting shaft 706, a fan blade 707, and a cover 705. The motor 701 is fixed to the inner wall of the casing 1 by bolts. The output end of the motor 701 is key-connected to the gear 702 to transmit rotational power. The gear 702 is meshed with the external teeth of the first gear ring 703. The first gear ring 703 is in an annular structure, and internal teeth are provided on the inner side of the first gear ring 703, which are meshed with the external teeth of the second gear ring 704. The second gear ring 704 is fixedly connected to the connecting shaft 706 by a key or welding. The connecting shaft 706 is a high-temperature resistant metal shaft. One end of the connecting shaft 706 is connected to the second gear ring 704, and the other end is rotatably connected to the cover 705 through a bearing. The cover 705 is in a hollow cylindrical structure and is made of a high-temperature resistant material (such as stainless steel). It is fixed to the casing 1 by bolts, and the fixing structure does not pass through the inside of the annular plate 802 and does not affect the rotation of the annular plate 802 driving the cover body 605. It is used to protect the fan blade 707 and guide the air flow. The fan blade 707 is fixedly connected to the end of the connecting shaft 706. The fan blade 707 is arranged inside the cover 705 and is preferably a multi-blade structure, which is used to generate air flow during rotation to assist in heat dissipation or promote gas circulation inside the casing 1. Among them, during the meshing rotation of the first gear ring 703 and the gear 702, they are not on the same plane as the cover body 605. When the two are in transmission, the cover body 605 does not contact the gear 702.

[0085] During actual use, after the material naturally cools down to below 60 degrees, the door body 3 is then opened, and the box body 1 is moved so that the box body 1 is completely attached below the cover body 605. After the motor 701 is started, the output end of the motor 701 drives the gear 702 to rotate, and the gear 702 drives the first gear ring 703 to rotate through meshing with the first gear ring 703. The inner teeth of the first gear ring 703 further drive the second gear ring 704 to rotate, thereby driving the fan blade 707 to rotate within the cover body 705 through the connecting shaft 706. The airflow generated by the rotation of the fan blade 707 blows the hot air inside the machine shell 1 to the outside. At the same time, during the rotation of the first gear ring 703, it will also drive the box body 601 and the cover body 605 to rotate. During the rotation, the internal material is turned over. Since the filter screen 604 on the cover body 605 can conduct the heat of the material to the outside. At the same time, relying on the airflow generated by the rotation of the fan blade 707, the heat dissipation effect is accelerated. In this application, the motor 701 indirectly drives the fan blade 707 to rotate, generating an airflow to quickly blow out the hot air inside the box body 601. At the same time, the filter screen 604 on the cover body 605 assists in conducting the heat to the outside. The dual heat dissipation mechanism significantly improves the heat dissipation efficiency. At the same time, the rotation of the first gear ring 703 drives the box body 601 and the cover body 605 to rotate synchronously, enabling the internal material to be evenly turned over during the rotation, avoiding local overheating or uneven processing. It speeds up the heat dissipation speed of the material when the temperature is below 60 degrees, and improves the working efficiency of the staff during the preparation process.

[0086] In this embodiment, the calcining device further includes a moving mechanism 9. The moving mechanism 9 includes a protrusion 901, a baffle 902, a hand wheel 903, two limit rods 904, a screw 905, a moving platform 906, a mounting shaft 909, a round sleeve 908, a shifting block 907 and a torsion spring 910. The protrusion 901 is fixed to the bottom of the box body 601 by bolts or welding, and is preferably a rectangular protrusion structure, which is used to cooperate with the shifting block 907 to drive the box body 601 to move. The movement distance of the shifting block 907 is greater than the movement distance of the box body 601 and the protrusion 901. In this way, if the shifting block 907 drives the box body 601 to move to one end during the movement, the shifting block 907 is deflected at this time, and drives the torsion spring 910 to undergo elastic deformation, so that the shifting block 907 moves to the other side of the protrusion 901, so that the box body 601 can be driven to the other end during the next reciprocating movement. The shift block 907 is fixed to the outside of the circular sleeve 908 by welding. The circular sleeve 908 is a hollow cylindrical structure, which is sleeved on the mounting shaft 909 and rotatably connected to the mounting shaft 909 through a bearing to realize the rotation of the shift block 907. The torsion spring 910 is sleeved on the mounting shaft 909. The two ends of the torsion spring 910 are respectively fixedly connected to the inner wall of the circular sleeve 908 and the mounting shaft 909 by snaps or welding, and are used to provide elastic reset force after the shift block 907 shifts the protrusion 901. The mounting shaft 909 is fixed to the top of the moving platform 906 by bolts. The moving platform 906 is a rectangular platform. The bottom of the moving platform 906 is provided with a threaded hole threadedly connected to the screw 905, and two through holes are provided to be slidably connected to the two limit rods 904 to ensure that the moving platform 906 moves in a straight line. The positional relationship between the screw 905 and the two limit rods 904 is shown in the figure of the specification. Figure 11 As shown, the screw 905 and the two limiting rods 904 are not in the annular space of the annular plate 802, that is, the screw 905 and the two limiting rods 904 do not affect the annular plate 802 driving the cover 605 to rotate. The two limiting rods 904 are high-temperature resistant stainless steel rods, and their two ends are respectively fixed to the baffle 902 and the inner wall of the housing 1 by bolts, which are used to limit the moving direction of the moving platform 906 and enhance its stability. The screw 905 is a high-temperature resistant metal screw, and its two ends are respectively rotatably connected to the baffle 902 and the inner wall of the housing 1 by bearings. The end of the screw 905 close to the door body 3 is fixed with a hand wheel 903 through a key connection. The hand wheel 903 is made of heat-resistant material, which is convenient for the operator to manually rotate to drive the screw 905. The baffle 902 is a high temperature resistant metal plate, which is fixed to the arc plate 803 by bolts. The baffle 902 will not rotate with the cover 605 and other structures, and the position of the baffle 902 will not interfere with the normal rotation of the cover 605 and other structures. The baffle 902 is used to support the installation of the limit rod 904 and the screw rod 905.

[0087] In actual use, the operator rotates the hand wheel 903 to drive the screw 905 to rotate, and the screw 905 drives the moving platform 906 to move linearly in the housing 1 along the axial direction of the two limit rods 904 through threaded cooperation. The moving platform 906 drives the installation shaft 909, the round sleeve 908 and the shifting block 907 to move synchronously. The shifting block 907 contacts and shifts the protrusion 901, pushing the box body 601 along the predetermined track in the housing 1 to the calcination position below the heating port 5. After shifting the protrusion 901, the shifting block 907 is reset to the initial angle by the elastic force of the torsion spring 910 to prepare for the next shifting. The moving mechanism 9 ensures that the movement of the moving platform 906 and the box body 601 is accurate and stable through the cooperation of the limit rod 904 and the screw 905. After calcination is completed, the door body 3 is opened, and the operator rotates the hand wheel 903 in the opposite direction to make the moving platform 906 drive the box body 601 to move out of the heating area. The moving mechanism 9 does not require the user to reach into the heating port 5 to pull the high-temperature box body 601 when taking it out, which is convenient for the user to operate and greatly improves the operating safety.

[0088] In addition, another embodiment of the present invention further provides an application of a modified titanium dioxide catalyst having a hierarchical porous structure and highly dispersed copper active sites for catalyzing a CO2 reduction reaction under simulated sunlight. Specifically, a photocatalytic CO2 reduction reaction is carried out in a pure water phase under simulated sunlight. The reactor is a quartz glass sleeve with a volume of 60 mL equipped with a thermometer sleeve. The reaction temperature is adjusted to 25 degrees through a circulating water system, and the reaction is maintained under normal pressure. The light source is a 300W Xe lamp with a full-band configuration, and the light intensity is maintained at 300mW·cm by adjusting the current. -2 The performance of the samples prepared in Examples 1, 2 and Comparative Examples 1, 2 is shown in the attached drawings of the specification. Figure 6 As shown, it can be seen that compared with the control examples 1 and 2, the samples of Examples 1 and 2 have better CO2 photocatalytic activity, which is attributed to the excellent pore system of the samples of Examples 1 and 2.

[0089] This method successfully synthesized a copper-based titanium dioxide photocatalyst with a pancake-like morphology through the coordinated regulation of coordination chemistry and pyrolysis process. The catalyst showed excellent CO generation performance and stability in the photocatalytic CO2 reduction reaction, providing an efficient catalytic material system for artificial photosynthesis and low-carbon energy conversion.

[0090] During the preparation process, the topological structure guiding property of the MOF precursor (such as NH2-MIL-125(Ti)) was fully utilized. On the basis of retaining its three-dimensional ordered mesoporous framework, a hierarchical pore structure was constructed. This multilevel pore system significantly improved the specific surface area and mass transfer efficiency of the catalyst. At the same time, through the confinement effect of the MOF, in-situ doping and high dispersion of the copper active component in the titanium dioxide lattice were realized. The uniform distribution of the copper component not only increased the density of active sites of the catalyst, but also effectively inhibited the recombination of photo-generated electron-hole pairs by regulating the electronic structure, thus enhancing the photocatalytic efficiency.

[0091] Specifically, the preparation method of the present invention includes the following key steps: First, NH2-MIL-125(Ti) is synthesized by hydrothermal method as a template precursor; Subsequently, the precursor is dispersed in a mixed solvent of deionized water and anhydrous methanol, and a CuCl2 solution is added for a coordination reaction to prepare a copper-containing titanium dioxide precursor; Finally, through a programmed temperature pyrolysis process, the structural transformation of the MOF skeleton into copper-based titanium dioxide is realized under precisely controlled calcination conditions (such as heating rate, calcination temperature and time). The obtained catalyst inherits the morphological characteristics of the MOF template and at the same time has an optimized crystal structure and surface chemical properties.

[0092] The synergistic optimization design of the structure-performance of this copper-based titanium dioxide photocatalyst not only significantly improves the activity and selectivity of photocatalytic CO2 reduction, but also exhibits good cycle stability and environmental adaptability. The method of the present invention has simple process and high repeatability, is suitable for large-scale preparation, and provides important theoretical basis and technical support for the development of efficient photocatalytic materials and the promotion of low-carbon energy conversion technology.

[0093] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a modified titanium dioxide catalyst, characterized in that It includes the following steps: S1: Dissolve a titanium source and an organic ligand in a solvent, and obtain a titanium-based MOF framework by a hydrothermal synthesis method; S2: Calcinate the titanium-based MOF framework in an air atmosphere, and obtain a modified titanium dioxide catalyst after cooling.

2. The preparation method of the modified titanium dioxide catalyst according to claim 1, characterized in that, It also includes the following steps: S101: Disperse the titanium-based MOF framework in a solvent, add a copper salt solution for impregnation, stir and then dry to obtain a copper-containing precursor.

3. The preparation method of the modified titanium dioxide catalyst according to claim 1, characterized in that, In step S2, the titanium-based MOF framework is calcined to obtain a cake-shaped nano titanium dioxide catalyst.

4. The preparation method of the modified titanium dioxide catalyst according to claim 2, characterized in that, In step S2, the copper-containing precursor is calcined to obtain a copper-based cake-shaped nano titanium dioxide catalyst.

5. The preparation method of the modified titanium dioxide catalyst according to claim 1, characterized in that, In step S3, the calcination temperature is 450 °C, the calcination time is 2 h, the heating rate is 2 °C per minute, and it is naturally cooled to below 60 °C. The solvent used for impregnation in step S1 is a mixed solvent of water and anhydrous methanol. The copper-containing precursor is calcined at 300 - 500 °C for 0.5 - 4 h in an air atmosphere. The reaction temperature of the hydrothermal synthesis in step S1 is 150 °C and the reaction time is 24 h.

6. The preparation method of the modified titanium dioxide catalyst according to claim 1, characterized in that, The titanium-based MOF framework in step S1 is NH2-MIL-125(Ti), and the copper salt solution is a copper chloride solution.

7. The preparation method of the modified titanium dioxide catalyst according to claim 5, characterized in that, Use a calcination device to calcine the titanium-based MOF framework in step S2, which includes a machine shell (1), a control unit (2), a door body (3), a locking mechanism (4), a heating port (5) and an auxiliary mechanism (6). The heating port (5) is arranged on the machine shell (1), the door body (3) faces the heating port (5), the door body (3) is connected to the machine shell (1), and the door body (3) is connected to the machine shell (1) through the locking mechanism (4); The auxiliary mechanism (6) includes a box body (601), a receiving groove (603), a first stop block (602), a second stop block (609), a filter screen (604), a cover body (605), a back plate (606), a rod body (607) and a magnetic block (608); A filter screen (604) is detachably connected above the cover body (605), the bottom of the cover body (605) fits with the top of the box body (601), the receiving groove (603) is processed on the box body (601), a first stop block (602) and a second stop block (609) are respectively connected to one side of the box body (601) away from the door body (3) and one side close to the door body (3), the cover body (605) is connected to the back plate (606), the back plate (606) is connected to the rod body (607), the rod body (607) is slidably connected to the second stop block (609), and the end of the rod body (607) close to the second stop block (609) is connected to the magnetic block (608).

8. The preparation method of the modified titanium dioxide catalyst according to claim 7, characterized in that, The calcination device also includes a driving mechanism (7) and a support mechanism (8); The support mechanism (8) includes two annular grooves (801), two annular plates (802), two arc plates (803), a plurality of clamping blocks (804) and a connecting rod (805); Both of the two annular plates (802) are connected to the cover body (605). The two annular grooves (801) are respectively machined on the two annular plates (802). A plurality of the clamping blocks (804) are respectively slidably connected to the two annular grooves (801). A plurality of the clamping blocks (804) are respectively connected to the two arc-shaped plates (803). The two arc-shaped plates (803) are connected by a connecting rod (805). The two arc-shaped plates (803) are connected to the machine housing (1). The driving mechanism (7) includes a motor (701), a gear (702), a first gear ring (703), a second gear ring (704), a connecting shaft (706), a fan blade (707) and a cover body (705). The motor (701) is connected to the machine housing (1). The output end of the motor (701) is connected to the gear (702). The gear (702) is meshed and connected with the first gear ring (703). The inner side of the first gear ring (703) is meshed and connected with the second gear ring (704). The second gear ring (704) is connected to the connecting shaft (706). The connecting shaft (706) is rotatably connected to the cover body (705). The cover body (705) is connected to the machine housing (1). The connecting shaft (706) is connected to the fan blade (707). The fan blade (707) is arranged inside the cover body (705).

9. The preparation method of the modified titanium dioxide catalyst according to claim 8, wherein, It further includes a moving mechanism (9). The moving mechanism (9) includes a convex block (901), a baffle (902), a hand wheel (903), two limiting rods (904), a screw rod (905), a moving table (906), a mounting shaft (909), a round sleeve (908), a shifting block (907) and a torsion spring (910). The convex block (901) is connected to the bottom of the box body (601). The shifting block (907) can shift the convex block (901) to move. The shifting block (907) is connected to the round sleeve (908). The round sleeve (908) is rotatably connected to the mounting shaft (909). The torsion spring (910) is sleeved on the mounting shaft (909). Two ends of the torsion spring (910) are respectively connected to one side of the round sleeve (908) and the mounting shaft (909). The mounting shaft (909) is connected to the moving table (906). The moving table (906) is in threaded connection with the screw rod (905). The moving table (906) is slidably connected to the two limiting rods (904). Two ends of the two limiting rods (904) are respectively connected to the baffle (902) and the machine housing (1). Two sides of the screw rod (905) are respectively rotatably connected to the baffle (902) and the machine housing (1). One side of the screw rod (905) close to the door body (3) is connected to the hand wheel (903). The baffle (902) is connected to the arc-shaped plate (803).

10. Application of a modified titanium dioxide catalyst, characterized in that, The modified titanium dioxide catalyst is a copper-based cake-shaped nano-titanium dioxide catalyst prepared by the preparation method described in any one of claims 1-9. The catalyst has a hierarchical porous structure and highly dispersed copper active sites, and is used for catalyzing the CO2 reduction reaction under simulated sunlight irradiation.

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