Apparatus and method for regenerating spent catalyst

Abstract

The application relates to a device and method for regenerating waste catalysts, belonging to the field of solid waste catalyst recycling. After being ground, the waste catalysts enter a plasma discharge area under the action of a blower, are in a fluidized state in a bed layer, are activated by plasma generated by an equal dielectric barrier discharge (DBD) device, enter a cyclone separator, and the separated waste catalyst powder is recycled to the plasma discharge area through a return pipeline. The device is divided into two modules. The first module utilizes argon and oxygen plasma to degrade the carbon and sulfides in the waste catalysts, effectively increasing the active area of the precious metals. The second module utilizes hydrogen to reduce the precious metal oxides in the waste catalysts, increasing the concentration of the precious metals, and thus realizing the regeneration of the waste catalysts. After the waste catalysts are treated, water vapor is introduced into the device to generate water vapor plasma to clean the device to prevent clogging, prolong the service life of the device, and improve the quality of the products.

Description

Technical Field

[0001] This invention specifically relates to an apparatus and method for regenerating waste catalysts based on plasma fluidized bed circulation technology, belonging to the field of waste catalyst recycling. Background Technology

[0002] Precious metal catalysts have been widely used in chemical, pharmaceutical, environmental protection, and new energy fields. For example, in automobile exhaust treatment, precious metal catalysts such as rhodium, palladium, and platinum can convert harmful substances in exhaust gases into harmless substances; in chemical synthesis, precious metal catalysts such as platinum, palladium, gold, and silver can promote the reaction of organic compounds, improving reaction efficiency and yield; in the field of energy conversion, precious metal catalysts are also widely used in fuel cells, solar cells, and other fields. However, catalysts are prone to deactivation during the reaction process due to high-temperature sintering or coke deposition. This is mainly because the catalyst surface or pores are blocked, leading to a reduction in active sites. In addition, some precious metal elements can also undergo oxidation reactions, reducing catalyst activity and hindering industrial production applications.

[0003] In recent years, the efficient utilization of spent catalysts has become a research hotspot in the field of industrial catalysis. Traditional methods for recovering precious metals from spent catalysts mainly include mechanical dismantling, chemical leaching, or incineration. However, these methods not only have low recovery rates, are cumbersome, time-consuming, and energy-intensive, but also pollute the environment.

[0004] Plasma is considered the fourth state of matter, composed of charged particles such as electrons, ions, and free radicals, as well as active groups, exhibiting high energy density and reactivity. Plasma activation technology is considered a promising dry regeneration technology for spent catalysts. It can directly act on impurities such as carbon deposits and sulfides on the catalyst surface or inside the pores, effectively removing covered catalyst active sites. Simultaneously, it avoids the problems of complex processes, cumbersome steps, high consumption of organic solvents, and large amounts of waste generated by traditional treatment methods, greatly improving economic efficiency. Furthermore, plasma devices have a simple structure, are environmentally friendly, continuously controllable, highly efficient, and flexible, making them easier to scale up and industrialize. For example, hydrogen can be used as the working gas to reduce oxidized precious metals in spent catalysts; on the other hand, the high-energy electrons and free radicals generated by introducing oxygen can efficiently remove impurities such as carbon deposits and sulfides from spent catalysts, significantly increasing the number of active sites. In addition, using modular, fluidized bed technology for the recycling of spent catalyst powder can make the activation of spent catalysts more thorough and uniform, while reducing coking during the treatment process. Therefore, developing waste catalyst regeneration devices and methods based on plasma fluidized bed circulation technology is of great significance for the efficient utilization of waste catalysts. Summary of the Invention

[0005] To address the shortcomings of traditional waste catalyst recycling technologies, this invention provides an apparatus and method for regenerating waste catalysts based on plasma fluidized bed circulation technology, particularly relating to an apparatus and method for treating waste catalysts based on DBD (plasma medium) plasma technology and fluidized bed.

[0006] The technical solution of this invention:

[0007] An apparatus for regenerating waste catalysts includes a feeding tank, two independent DBD plasma plasma devices, a gas cylinder, a blower, two independent cyclone separators, two independent waste gas treatment devices, a receiving tank, a transfer valve, a return valve, and a steam generator. The apparatus is divided into two modules by the transfer valve. The feeding tank and the gas cylinder providing the precursor gas are connected via pipelines to the material inlet and gas inlet of the DBD plasma device in the first module, respectively. The material and gas outlets of the DBD plasma device in the first module are connected to the inlet of the cyclone separator in the first module. The gas outlet of the cyclone separator in the first module is connected to the first waste gas treatment device. Two valves are installed at the material outlet of the air separator. One valve connects to the bottom of the DBD plasma device in the first module via a return valve, and the other valve connects to the DBD plasma device in the second module via a transfer valve. The cylinder providing the precursor gas is connected to the gas inlet of the DBD plasma device in the second module via a pipeline. The material and gas outlets of the DBD plasma device in the second module are connected to the inlet of the cyclone separator in the second module. The gas outlet of the cyclone separator in the second module is connected to the second waste gas treatment device, and the material outlet of the cyclone separator in the second module is connected to the bottom of the DBD plasma device in the second module on one hand and to the receiving trough on the other. Material conveying between the two modules is achieved by a blower.

[0008] The DBD plasma device is equipped with a copper rod and a copper mesh. The copper rod is fixed inside the DBD plasma device cavity, and the copper mesh is wrapped around the outside of the DBD plasma device cavity wall at the same height as the copper rod, forming a plasma discharge area. The copper rod is connected to a high-frequency AC power supply, and the copper mesh is directly connected to the ground wire.

[0009] The steam generator is connected to the bottom of the DBD plasma device in each of the two modules.

[0010] A method for regenerating spent catalysts is as follows:

[0011] After grinding, the spent catalyst enters the bottom of the DBD plasma device in the first module via a feed trough, and is blown into the plasma discharge area of ​​the first module by a blower; gas cylinders supply precursor atmosphere to the plasma treatment area of ​​the device, and under the action of high-frequency voltage, Ar and O2 decompose to produce high-energy electrons, Ar +Ar 2+ O2 - Ions and oxygen free radical active particles can effectively crack carbon deposits and sulfides in waste catalysts, achieving efficient activation of the waste catalysts. Further, the cyclone separator in the first module separates the regenerated catalyst powder and waste gas. The waste gas enters the first waste gas treatment device through the exhaust pipe, while the separated waste catalyst is returned to the plasma treatment area of ​​the first module for recycling, continuously removing carbon deposits, moisture, and sulfides. After several cycles, the waste catalyst is transported to the plasma chamber area of ​​the second module through a transfer valve. H2 is introduced and hydrogen plasma is generated through high-frequency voltage to reduce the precious metal oxides in the waste catalyst. The operation of the first module is repeated, and finally, the completely reduced waste catalyst is transferred to the collection tank. Then, water vapor is introduced into the device, generating water vapor plasma under high-voltage electricity to clean the coking residue on the inner wall of the DBD plasma device. While the second module is operating, the first module can be simultaneously activated for the next round of waste catalyst regeneration.

[0012] The device for regenerating waste catalyst described above is specifically configured as follows: The device for regenerating waste catalyst includes a feed tank 1, a feed blower 2-1, a circulating blower A2-2, a circulating blower B2-3, a circulating blower C2-4, a circulating blower D2-5, a feed valve 3-1, a return valve A3-2, a return valve B3-4, a transfer valve 3-3, a discharge valve 3-5, copper rods A4-1 and B4-2, copper mesh A5-1 and B5-2, a ground wire A6-1 and B6-2, and an oxygen cylinder 7-1. Argon cylinder 7-2, Hydrogen cylinder 7-3, Check valve A8-1, Check valve B8-2, Check valve C8-3, Check valve D8-4, Exhaust gas pipeline A9-1, Exhaust gas pipeline B9-2, Cyclone separator A10-1, Cyclone separator B10-2, Steam generator 11, Mass flow controller A12-1, Mass flow controller B12-2, Mass flow controller C12-3, Exhaust gas treatment device A13-1, Exhaust gas treatment device B13-2, Discharge trough 14, High-frequency AC power supply 15;

[0013] Feed trough 1 is connected to the material inlet at the bottom of the first plasma fluidized bed via a pipe. A feed valve 3-1 is installed at the material inlet at the bottom of the first plasma fluidized bed. A feed blower 2-1 is installed on the pipe at the front end of feed trough 1. A copper rod A4-1 is inserted and fixed at the center of the first plasma fluidized bed, and the high-voltage electrode on the copper rod A4-1 is connected to a high-frequency AC power supply 15. A copper mesh A5-1 covers the outer wall of the first plasma fluidized bed, is at the same height as the copper rod A4-1, and is directly connected to the ground wire A6-1. The outer wall of the first plasma fluidized bed covering the copper mesh A5-1 needs to be made of insulating material. A circulating blower A2-2 and a circulating blower B2-3 are installed at the bottom and top of the first plasma fluidized bed, respectively. The blowing direction of the circulating blower A2-2 is from bottom to top, and the blowing direction of the circulating blower B2-3 is the same as that of the circulating blower A2-2. The wind direction is 90°; circulating blowers A2-2 and B2-3 work together to blow materials into cyclone separator A10-1; the bottom of the first plasma fluidized bed is also connected to oxygen cylinder 7-1 and argon cylinder 7-2 through pipes, and mass flow controllers A12-1 and B12-2 are respectively installed on the pipes, both equipped with check valves B8-2; the bottom of the first plasma fluidized bed is also connected to steam generator 11 through pipes, and check valves A8-1 are installed on the pipes; a transfer valve 3-3 is installed at the bottom of cyclone separator A10-1, which is connected to the bottom of the first plasma fluidized bed through a pipe, and a return valve A3-2 is installed on the pipe; it is also connected to the bottom of the second plasma fluidized bed through a pipe; the top of cyclone separator A10-1 is connected to waste gas treatment device A13-1 through waste gas pipe A9-1;

[0014] A copper rod B4-2 is inserted and fixed at the center of the second plasma fluidized bed, and the high-voltage electrode on the copper rod B4-2 is connected to the high-frequency AC power supply 15; a copper mesh B5-2 covers the outer wall of the second plasma fluidized bed, is at the same height as the copper rod B4-2, and is directly connected to the ground wire B6-2; the outer wall of the second plasma fluidized bed covering the copper mesh B5-2 needs to be an insulating material; a circulating blower C2-4 and a circulating blower D2-5 are respectively installed at the bottom and top of the second plasma fluidized bed; the blowing direction of the circulating blower C2-4 is from bottom to top, and the blowing direction of the circulating blower D2-5 is at 90° to the blowing direction of the circulating blower C2-4; the circulating blowers C2-4 and D2-5... Machine D2-5 is used to blow materials into cyclone separator B10-2; the bottom of the second plasma fluidized bed is also connected to hydrogen cylinder 7-3 and steam generator 11 through pipes, and check valves D8-4 and C8-3 are respectively installed on the pipes. A mass flow controller C12-3 is installed between check valve D8-4 and hydrogen cylinder 7-3; a discharge valve 3-5 is installed at the bottom of cyclone separator B10-2; on one hand, it is connected to the bottom of the second plasma fluidized bed through a pipe, and a return valve B3-4 is installed on the pipe; on the other hand, it is connected to the discharge trough 14 through discharge valve 3-5; the top of cyclone separator B10-2 is connected to waste gas treatment device B13-2 through waste gas pipe B9-2.

[0015] Furthermore, a method for regenerating spent catalysts using the aforementioned apparatus is described. The steps are as follows:

[0016] 1) After the waste catalyst is ground, it is poured into the feed tank 1, and the feed blower 2-1 and feed valve 3-1 are turned on to allow the catalyst powder to enter the bottom of the first plasma fluidized bed;

[0017] 2) Turn on circulating blowers A2-2 and B2-3 to blow the waste catalyst powder into the discharge area of ​​the first plasma fluidized bed;

[0018] 3) Open the gas shut-off valve B8-2, and control the oxygen precursor gas in oxygen cylinder 7-1 and the argon precursor gas in argon cylinder 7-2 to be injected into the discharge area of ​​copper mesh A5-1 at a certain flow rate through mass flow controllers A12-1 and B12-2; at the same time, turn on the high-frequency AC power supply 15, and under the action of the high-voltage electric field, a discharge area is formed between copper rod A4-1 and copper mesh A5-1. The gas is decomposed into various excited-state active species, which degrades and eliminates the carbon deposits and toxic sulfides in the waste catalyst powder;

[0019] 4) The waste catalyst flows into the cyclone separator A10-1, the return valve A3-2 is opened, and the transfer valve 3-3 remains closed; the cyclone separator A10-1 separates part of the activated waste catalyst powder from the gas flow and returns it to the discharge area of ​​the first plasma fluidized bed for recycling through the return valve; the waste gas generated by the degradation of the first plasma fluidized bed is discharged from the upper end of the cyclone separator A10-1 through the waste gas pipeline A9-1 to the waste gas treatment device A13-1;

[0020] 5) After 5 to 10 cycles of treatment in steps 2 to 4, stop the oxygen supply, maintain the argon supply for a period of time, and remove the oxygen from the device; further close the return valve A3-2, open the transfer valve 3-3 until the waste catalyst is completely transferred to the second plasma fluidized bed, close the transfer valve 3-3, and at this time, the above steps 1 to 4 can be repeated, and new waste catalyst powder can be added to make the first plasma fluidized bed complete a new batch of activation;

[0021] 6) In the second plasma fluidized bed, turn on the circulating blower C2-4 and the circulating blower D2-5 to blow the waste catalyst powder into the discharge area of ​​the second plasma fluidized bed;

[0022] 7) Open the gas shut-off valve D8-4, and control the hydrogen precursor gas in hydrogen cylinder 7-3 to be injected into the discharge area of ​​copper mesh B5-2 at a certain flow rate through mass flow controller C12-3; at the same time, turn on the high-frequency AC power supply 15, and under the action of high voltage electric field, a discharge area is formed between copper rod B4-2 and copper mesh B5-2, and the hydrogen drive atmosphere is cracked to generate high-energy electrons, reducing the noble metal oxides in the waste catalyst.

[0023] 8) Waste catalyst flows into cyclone separator B10-2, return valve B3-4 is opened, and discharge valve 3-5 remains closed; cyclone separator B10-2 is used to separate part of the activated catalyst powder from the gas flow, and it is sent back to the discharge area of ​​the second plasma fluidized bed for recycling through the return valve; while the waste gas generated by the degradation in the second plasma fluidized bed is discharged from the upper end of cyclone separator B10-2 through exhaust pipe B9-2 to waste gas treatment device B13-2;

[0024] 9) After 5 to 10 cycles, the waste catalyst is basically activated. Close the return valve B3-4 and open the discharge valve 3-5 to discharge the activated waste catalyst into the discharge tank 14.

[0025] 10) After each 5-10 cycles of processing in the first and second plasma fluidized beds, decoking will be performed: close the feed valve 3-1, transfer valve 3-3, and discharge valve 3-5; turn on the circulating blowers A2-2, B2-3, C2-4, and D2-5; open the check valves A8-1 and C8-3; and introduce steam into the first and second plasma fluidized beds from the steam generator 11. Turn on the high-frequency AC power supply 15 to generate steam plasma. Further, open the transfer valve 3-3 and discharge valve 3-5, and close the return valves A3-2 and B3-4. Use the blowers to discharge the detached coking residue from the discharge valve 3-5, achieving the effect of cleaning the inside of the device.

[0026] In step (1), the particle size of the waste catalyst is 50nm to 500μm to ensure that the waste catalyst powder can be blown into the device cavity by the blower and circulated in the device.

[0027] The flow rates of the precursor gas in steps (3) and (7) and the water vapor in step (10) are 1 to 100 slm.

[0028] The AC high voltage applied in steps (3), (7) and (10) ensures that the output power is 10 to 1000W to stably generate plasma.

[0029] After stopping the oxygen supply in step (5), the argon supply time is 2-3 minutes, and the flow rate is the same as in step (3).

[0030] In steps (5) and (9), the waste catalyst is recycled 5 to 10 times to ensure that the waste catalyst is fully activated and reduced.

[0031] The steam plasma treatment in step (10) lasts for 3 to 6 minutes to ensure that the coking products are fully removed.

[0032] The outer wall of the plasma fluidized bed is insulated with high-temperature resistant inorganic materials such as quartz or ceramic, or high-temperature resistant polymer materials such as polytetrafluoroethylene (PTFE), polyphenylene sulfide (PBS), polyether ether ketone (PEEK), polyphenylene oxide (PPOB), and polyphenylene ether (PPO). The plasma fluidized bed exhibits dielectric barrier discharge. High-temperature resistance refers to the ability to withstand temperatures above 250°C.

[0033] The waste gas from the waste gas treatment device A13-1 is introduced into an alkali tank to remove sulfides from the gas. The waste gas from the waste gas treatment device B13-2 is ignited to remove hydrogen from the gas.

[0034] The beneficial technical effects of this invention are as follows:

[0035] The main body of the activated spent catalyst unit includes, in sequence, a feeding tank, two independent DBD plasma devices, a gas cylinder, a blower, a cyclone separator, waste gas treatment pipelines and devices, a return pipeline, and a receiving tank. This unit can be divided into two modules by a transfer valve: the area connected to the feeding valve is the first module, and the area connected to the discharge valve is the second module. Each module has the same structure and can be divided into a plasma treatment area and a solid-gas separation area. The plasma treatment area includes the area containing the copper rods and copper mesh, as well as the blowers at the bottom and top. The solid-gas separation area includes the cyclone separator and the return pipeline containing the discharge valve. After grinding, the spent catalyst enters the bottom of the fluidized bed through the feeding tank and is blown into the plasma treatment area cavity of the first module by the blower. Furthermore, the gas cylinder device supplies a precursor atmosphere to the plasma treatment area of ​​the unit. Under the action of high-frequency voltage, Ar and O2 decompose to produce high-energy electrons and ions (Ar... + Ar 2+ O2 - Active particles such as oxygen free radicals are used to treat carbon deposits and sulfides in the spent catalyst powder, achieving activation and regeneration of the spent catalyst. Further, a cyclone separator in the solid-gas separation zone separates the regenerated catalyst powder and waste gas. The waste gas is discharged into the waste gas treatment device through the exhaust pipe, while the separated spent catalyst is returned to the plasma treatment area for recycling through the return pipe. After several cycles of activation treatment, the return pipe is closed, and the spent catalyst is transferred to the plasma treatment area cavity of the second module through the transfer pipe. The introduced precursor gas H2 is used to generate hydrogen plasma through high-frequency voltage, which acts on the noble metal oxides in the spent catalyst to reduce them. The operation of the first module is repeated, and finally, the fully activated spent catalyst is transferred to the receiving tank through the discharge pipe. After the first and second modules produce five products, water vapor is introduced into the device. Under the action of high-frequency voltage, it becomes water vapor plasma. The water vapor plasma is used to clean the coking products inside the tube wall, and the generated gas is discharged through the waste gas emission pipe. The coking product residue is discharged to the discharge tank through the discharge pipe. This invention, based on low-temperature plasma technology, utilizes a parallel fluidized bed to enable large-scale recycling of spent catalysts. The process is environmentally friendly, highly efficient, and controllable, providing a reference for the industrialization of spent catalyst regeneration technology. The reaction device of this invention features a simple structure, low energy consumption, cost savings, flexible operation, high efficiency and safety, and stable operation. It avoids the use of organic solvents, reducing costs, and eliminates the need for complex post-processing. The first and second modules operate synchronously, ensuring complete activation and preventing interference between spent catalyst activation processes, while simultaneously improving the processing efficiency of spent catalysts.

[0036] This invention uses steam plasma to clean the coking inside the device, which is simple, efficient, and can effectively prevent reactor blockage.

[0037] Note: Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be defined by the claims. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a device and method for activating a catalyst based on a plasma fluidized bed.

[0039] Figure 2 This is a TEM transmission electron microscope (TEM) comparison image of the waste Pd / Al2O3 catalyst before and after activation in Example 1 of this invention.

[0040] Figure 3 This is a comparison of the TGA thermogravimetric analysis curves of the spent Pd / Al2O3 catalyst before and after activation in Example 1 of this invention.

[0041] Figure 4 This is a comparison of XPS photoelectron spectra of the waste Pd / Al2O3 catalyst before and after activation in Example 1 of this invention.

[0042] Figure 5 This is a comparison of the electrochemical cyclic voltammetry (CV) curves of the spent Pd / Al2O3 catalyst before and after activation in Example 1 of this invention.

[0043] Figure 6 This is a comparison of the electrochemical cyclic voltammetry (CV) curves of the spent Pd / Al2O3 catalysts after activation in Examples 1 and 4 of this invention.

[0044] Figure 1 1. Feed chute; 2.1 Feed blower; 2.2 Circulating blower A; 2.3 Circulating blower B; 2.4 Circulating blower C; 2.5 Circulating blower D; 3.1 Feed valve; 3.2 Return valve A; 3.4 Return valve B; 3.3 Transfer valve; 3.5 Discharge valve; 4.1 Copper rod A; 4.2 Copper rod B; 5.1 Copper mesh A; 5.2 Copper mesh B; 6.1 Ground wire A; 6.2 Ground wire B; 7.1 Oxygen cylinder; 7.2 Argon cylinder; 7.3 Hydrogen cylinder; 8. 1. Check valve A; 8.2 Check valve B; 8.3 Check valve C; 8.4 Check valve D; 9.1 Exhaust gas pipeline A; 9.2 Exhaust gas pipeline B; 10.1 Cyclone separator A; 10.2 Cyclone separator B; 11. Steam generator; 12.1 Mass flow controller A; 12.2 Mass flow controller B; 12.3 Mass flow controller C; 13.1 Exhaust gas treatment device A; 13.2 Exhaust gas treatment device B; 14. Discharge trough; 15. High-frequency AC power supply. Detailed Implementation

[0045] The following examples further illustrate the method and effects of the present invention, but do not limit the scope of protection of the present invention.

[0046] Example 1

[0047] A 30mm diameter copper tube was used as the high-voltage electrode, and a quartz tube was used as the conduit for the DBD plasma device. Commercially available waste Pd / Al₂O₃ catalyst was selected as the raw material, ground into powder (particle size 50nm~500μm), and poured into the feed trough. The feed valve and blower were opened, and the waste catalyst powder entered the plasma fluidized bed of the first module. Two blowers were turned on to blow the waste Pd / Al₂O₃ powder into the discharge area. The check valve was opened, and the precursor gas mixture was adjusted to 30slm argon and oxygen via a mass flow controller and injected into the plasma treatment area. Simultaneously, the high-frequency AC power supply was turned on and the output power was controlled to 50W. The Ar precursor atmosphere and O₂ precursor gas were decomposed into various excited-state active species to degrade and eliminate carbon deposits in the waste Pd / Al₂O₃ powder. The waste catalyst was circulated 7 times within the first module. Further, the oxygen supply was stopped, and argon was continuously supplied for 2 minutes to purge the oxygen from the device. The check valve was then closed. Next, the return valve is closed, and the transfer valve is opened. The waste Pd / Al2O3 powder is separated by a cyclone separator and transferred to the plasma fluidized bed in the second module via the transfer valve. After all the waste catalyst powder has been transferred, the transfer valve is closed, two blowers are turned on, the high-frequency AC power supply is turned on, and the precursor gas is adjusted to 30 slm hydrogen. The operation of the first module is repeated. The high-energy electrons generated by the hydrogen plasma reduce the precious metals in the waste catalyst. After 7 cycles, the return valve is closed, and the discharge valve is opened. The activated Pd / Al2O3 catalyst powder enters the receiving tank. Next, the discharge valve is closed, and the return valves of both modules and the steam check valve are opened. The high-frequency AC power supply is turned on to generate steam plasma at a flow rate of 30 slm for 3 minutes. The return valve is closed, and the transfer valve and discharge valve are opened. The coking product residue that has detached from the copper mesh area is discharged from the discharge valve. After the residue is completely discharged, the transfer valve and discharge valve are closed, and the above operation is repeated.

[0048] Example 2

[0049] The processing technology and operating conditions are the same as in Example 1, except that the selected waste catalyst is waste Ag / Al2O3 powder.

[0050] Example 3

[0051] The processing technology and operating conditions are the same as in Example 1, except that the selected waste catalyst is waste Pt / C powder.

[0052] Example 4

[0053] The processing technology and operating conditions are the same as in Example 1, except that the selected waste Ag / Al2O3 powder is activated in three cycles.

[0054] Figure 2 TEM images reveal overlapping, irregularly arranged rod-shaped and sheet-like alumina nanostructures with a wide range of impurities adhering to their surfaces in the untreated spent catalyst. Figure 2 (Left). After plasma treatment, the catalyst surface becomes clean and free of impurities. Figure 2 (Right) This further verifies that plasma treatment can effectively remove impurities such as carbon deposits on the catalyst surface.

[0055] Figure 3 Thermogravimetric analysis (TGA) results show that the initial mass loss from 50°C to 150°C is due to the absorption of water and the removal of surface hydroxyl groups. The untreated spent catalyst experienced a sharp mass loss in the temperature range of 200–300°C, continuing until the temperature rose to 500°C, at which point the mass of the spent catalyst decreased to 75% of the original catalyst. The carbon deposits on the catalyst during calcination underwent pyrolysis, leading to the mass reduction. The activated spent catalyst showed a smaller weight loss, which can be explained by the fact that plasma removed most of the carbon deposits during the activation process.

[0056] Figure 4 XPS characterization of the chemical states of surface elements in the catalyst. The content of different valence states of Pd is shown in the figure. The Pd 3d fitting and deconvolution yielded four peaks, which were assigned to Pd2+3d3 / 2 (~350 eV), Pd0 3d3 / 2 (~347 eV), Pd2+3d5 / 2 (~331 eV), and Pd0 3d5 / 2 (~336 eV), respectively. In the figure, the peak area of ​​Pd0 in the activated spent catalyst increased, indicating an increase in Pd0 content. Since the electrochemical performance of Pd0 is better than that of Pd2+, the electrochemical performance of the activated spent catalyst is better than that of the untreated spent catalyst.

[0057] Figure 5 The electrochemical cyclic voltammetry (CV) curves of the spent catalyst after primary treatment were obtained. The difference between the peak values ​​at the anode and cathode was used to determine the electrochemical performance. The difference between the peak values ​​of the activated spent catalyst and the untreated catalyst was higher, indicating that the activated spent catalyst has better electrochemical performance.

[0058] Figure 6 Electrochemical CV cyclic voltammetry curves of spent catalysts after three treatments, and... Figure 5 Comparative studies have shown that, within a certain range, the electrochemical performance of spent catalysts that have undergone multiple treatments is superior to that of spent catalysts that have undergone a single treatment.

[0059] The above embodiments are merely illustrative of the process flow of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, or improvements made by those skilled in the art without departing from the principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for regenerating waste catalyst, characterized in that, The device for regenerating waste catalyst includes a feed trough, two independent DBD plasma devices, a gas cylinder, a blower, two independent cyclone separators, two independent waste gas treatment devices, a receiving trough, a transfer valve, a return valve, and a steam generator. The device is divided into two modules by the transfer valve. The feed trough and the gas cylinder providing the precursor gas are connected via pipelines to the material inlet and gas inlet of the DBD plasma device in the first module, respectively. The material and gas outlets of the DBD plasma device in the first module are connected to the inlet of the cyclone separator in the first module. The gas outlet of the cyclone separator in the first module is connected to the first waste gas treatment device, and the material outlet of the cyclone separator in the first module... Two valves are installed at the site. One valve connects to the bottom of the DBD plasma device in the first module via a return valve, and the other valve connects to the DBD plasma device in the second module via a transfer valve. A cylinder supplying precursor gas is connected to the gas inlet of the DBD plasma device in the second module via a pipeline. The material and gas outlets of the DBD plasma device in the second module are connected to the inlet of the cyclone separator in the second module. The gas outlet of the cyclone separator in the second module is connected to the second waste gas treatment device, and the material outlet of the cyclone separator in the second module is connected to the bottom of the DBD plasma device in the second module on one hand and to the receiving trough on the other. Material conveying between the two modules is achieved by a blower. The DBD plasma device is equipped with a copper rod and a copper mesh. The copper rod is fixed inside the DBD plasma device cavity, and the copper mesh is wrapped around the outside of the DBD plasma device cavity wall at the same height as the copper rod, forming a plasma discharge area. The copper rod and the copper mesh are respectively connected to a high-frequency AC power supply and ground. The steam generators are connected to the bottom of the DBD plasma devices in the two modules respectively; Includes a feed trough (1), a feed blower (2-1), a circulating blower A (2-2), a circulating blower B (2-3), a circulating blower C (2-4), a circulating blower D (2-5), a feed valve (3-1), a return valve A (3-2), a return valve B (3-4), a transfer valve (3-3), a discharge valve (3-5), copper rod A (4-1), copper rod B (4-2), copper mesh A (5-1), copper mesh B (5-2), ground wire A (6-1), ground wire B (6-2), an oxygen cylinder (7-1), an argon cylinder (7-2), and a hydrogen cylinder (7-3). ), Check valve A (8-1), Check valve B (8-2), Check valve C (8-3), Check valve D (8-4), Exhaust gas pipeline A (9-1), Exhaust gas pipeline B (9-2), Cyclone separator A (10-1), Cyclone separator B (10-2), Steam generator (11), Mass flow controller A (12-1), Mass flow controller B (12-2), Mass flow controller C (12-3), Exhaust gas treatment device A (13-1), Exhaust gas treatment device B (13-2), Discharge trough (14), High frequency AC power supply (15); The feed trough (1) is connected to the material inlet at the bottom of the first plasma fluidized bed via a pipe. A feed valve (3-1) is installed at the material inlet at the bottom of the first plasma fluidized bed. A feed blower (2-1) is installed on the pipe at the front end of the feed trough (1). A copper rod A (4-1) is inserted and fixed in the center of the first plasma fluidized bed, and the high-voltage electrode on the copper rod A (4-1) is connected to a high-frequency AC power supply (15). A copper mesh A (5-1) is wrapped around the outer wall of the first plasma fluidized bed. The copper mesh A (5-1) is at the same height as the copper rod A (4-1), and is directly connected to the ground wire A (6-1); the outer wall of the first plasma fluidized bed covering the copper mesh A (5-1) needs to be made of insulating material; a circulating blower A (2-2) and a circulating blower B (2-3) are respectively installed at the bottom and top of the first plasma fluidized bed; the blowing direction of the circulating blower A (2-2) is from bottom to top, and the blowing direction of the circulating blower B (2-3) is the same as that of the circulating blower A (2-2). The airflow direction is 90°; circulating blowers A (2-2) and B (2-3) work together to blow the material into cyclone separator A (10-1); the bottom of the first plasma fluidized bed is also connected to oxygen cylinder (7-1) and argon cylinder (7-2) through pipes, and mass flow controllers A (12-1) and B (12-2) are respectively installed on the pipes, both equipped with check valves B (8-2); the bottom of the first plasma fluidized bed is also connected to... It is connected to the steam generator (11) and a gas shut-off valve A (8-1) is installed on the pipeline; a transfer valve (3-3) is installed at the bottom of the cyclone separator A (10-1), which is connected to the bottom of the first plasma fluidized bed through a pipeline and a return valve A (3-2) is installed on the pipeline; and is connected to the bottom of the second plasma fluidized bed through a pipeline; the top of the cyclone separator A (10-1) is connected to the waste gas treatment device A (13-1) through the waste gas pipeline A (9-1); A copper rod B (4-2) is inserted and fixed at the center of the second plasma fluidized bed, and the high-voltage electrode on the copper rod B (4-2) is connected to a high-frequency AC power supply (15); a copper mesh B (5-2) covers the outer wall of the second plasma fluidized bed, is at the same height as the copper rod B (4-2), and the copper mesh B (5-2) is directly connected to the ground wire B (6-2); the outer wall of the second plasma fluidized bed covering the copper mesh B (5-2) needs to be an insulating material; a circulating blower C (2-4) and a circulating blower D (2-5) are respectively installed at the bottom and top of the second plasma fluidized bed; the blowing direction of the circulating blower C (2-4) is from bottom to top, and the blowing direction of the circulating blower D (2-5) is 90° to the blowing direction of the circulating blower C (2-4); the circulating blowers C (2-4) and D (5-5) are connected to the ground wire B (6-2); the copper mesh B (5-2) covers the outer wall of the second plasma fluidized bed, is at the same height as the copper rod B (4-2), and the copper mesh B (5-2) is directly ... bottom and top of the second plasma fluidized bed, respectively; the circulating blower C (2-4) blows air from bottom to top, and the circulating blower D (5-5) blows air from bottom to top 2-5) Used to blow materials into cyclone separator B (10-2); the bottom of the second plasma fluidized bed is also connected to the hydrogen cylinder (7-3) and the steam generator (11) through pipes, and the pipes are respectively equipped with check valve D (8-4) and check valve C (8-3), and a mass flow controller C (12-3) is set between check valve D (8-4) and hydrogen cylinder (7-3); the bottom of cyclone separator B (10-2) is equipped with discharge valve (3-5); on one hand, it is connected to the bottom of the second plasma fluidized bed through a pipe, and the pipe is equipped with return valve B (3-4); on the other hand, it is connected to discharge trough (14) through discharge valve (3-5); the top of cyclone separator B (10-2) is connected to waste gas treatment device B (13-2) through waste gas pipe B (9-2).

2. A method for regenerating spent catalyst using the apparatus for regenerating spent catalyst as described in any one of claims 1, characterized in that, Specifically as follows: After grinding, the spent catalyst enters the bottom of the DBD plasma device in the first module via a feed trough, and is blown into the plasma discharge area of ​​the first module by a blower; the gas cylinder provides the working gas for the plasma of the device. Under the action of high-frequency voltage, Ar and O2 are decomposed to produce high-energy electrons, Ar... + Ar 2+ O2 - Ions and oxygen free radical active particles can effectively crack carbon deposits, sulfides, and moisture in waste catalysts, achieving efficient activation of the waste catalysts. Further, the cyclone separator in the first module separates the regenerated catalyst powder and waste gas. The waste gas enters the first waste gas treatment device through the exhaust pipe, while the separated waste catalyst is returned to the plasma treatment area of ​​the first module for recycling, continuously removing carbon deposits, sulfides, and moisture. After several cycles, the waste catalyst is transported to the plasma chamber area of ​​the second module via a transfer valve. H2 is introduced and high-frequency voltage generates hydrogen plasma to reduce the precious metal oxides in the waste catalyst, repeating the operation of the first module. Finally, the completely reduced waste catalyst is transferred to the collection tank. Then, water vapor is introduced into the device, generating water vapor plasma under high-voltage electricity to clean the coking residue on the inner wall of the device. While the second module is operating, the first module can be simultaneously activated for the next round of waste catalyst regeneration.

3. The method according to claim 2, characterized in that, The specific steps are as follows: (1) After the waste catalyst is ground, it is poured into the feed tank (1), and the feed blower (2-1) and feed valve (3-1) are turned on so that the catalyst powder enters the bottom of the first plasma fluidized bed; (2) Turn on the circulating blower A (2-2) and circulating blower B (2-3) to blow the waste catalyst powder into the discharge area of ​​the first plasma fluidized bed; (3) Open the gas stop valve B (8-2), and control the oxygen precursor gas in the oxygen cylinder (7-1) and the argon precursor gas in the argon cylinder (7-2) to be injected into the discharge area of ​​the copper mesh A (5-1) at a certain flow rate through the mass flow controller A (12-1) and the mass flow controller B (12-2); at the same time, turn on the high frequency AC power supply (15), and under the action of the high voltage electric field, a discharge is formed between the copper rod A (4-1) and the copper mesh A (5-1), and the gas is decomposed into various excited active species, which degrades and eliminates the carbon deposits, sulfides and moisture in the waste catalyst powder; (4) The waste catalyst flows into the cyclone separator A (10-1), the return valve A (3-2) is opened, and the transfer valve (3-3) is kept closed; the cyclone separator A (10-1) is used to return part of the activated waste catalyst powder to the discharge area of ​​the first plasma fluidized bed for recycling treatment; and the waste gas generated by the degradation of the first plasma fluidized bed is discharged from the upper end of the cyclone separator A (10-1) through the waste gas pipeline A (9-1) to the waste gas treatment device A (13-1); (5) After 5 to 10 cycles of step (2) to step (4), stop the oxygen supply, maintain the argon supply for a period of time, and exhaust the oxygen in the device; further close the return valve A (3-2), open the transfer valve (3-3) until the waste catalyst is completely transferred to the second plasma fluidized bed, close the transfer valve (3-3), and at this time, the above steps (1) to (4) can be repeated, and new waste catalyst powder can be added so that the first plasma fluidized bed can complete a new batch of activation; (6) In the second plasma fluidized bed, turn on the circulating blower C (2-4) and the circulating blower D (2-5) to blow the waste catalyst powder into the discharge area of ​​the second plasma fluidized bed; (7) Open the gas stop valve D (8-4) and control the hydrogen precursor gas in the hydrogen cylinder (7-3) to be injected into the discharge area at a certain flow rate through the mass flow controller C (12-3); at the same time, turn on the high frequency AC power supply (15) and under the action of the high voltage electric field, a discharge is formed between the copper rod B (4-2) and the copper mesh B (5-2), the hydrogen drive atmosphere is cracked to generate high-energy electrons, and the noble metal oxides in the waste catalyst are reduced. (8) The waste catalyst flows into the cyclone separator B (10-2), the return valve B (3-4) is opened, and the discharge valve (3-5) is kept closed; the cyclone separator B (10-2) is used to send part of the activated catalyst powder back to the discharge area of ​​the second plasma fluidized bed for recycling treatment; and the waste gas generated by the degradation of the second plasma fluidized bed is discharged from the top of the cyclone separator B (10-2) through the exhaust pipe B9-2 to the waste gas treatment device B (13-2); (9) After 5 to 10 cycles, the waste catalyst is basically regenerated. Close the return valve B (3-4) and open the discharge valve (3-5) to discharge the activated waste catalyst into the discharge tank (14). (10) After each unit of circulation processing is completed, the first plasma fluidized bed and the second plasma fluidized bed will perform decoking: close the feed valve (3-1), transfer valve (3-3), and discharge valve (3-5), open the circulating blower A (2-2), circulating blower B (2-3), circulating blower C (2-4), and circulating blower D (2-5), open the gas stop valve A (8-1) and gas stop valve C (8-3), and introduce water vapor into the first plasma fluidized bed and the second plasma fluidized bed from the steam generator (11); turn on the high-frequency AC power supply (15) to generate water vapor plasma; further, open the transfer valve (3-3) and discharge valve (3-5), close the return valve A (3-2) and return valve B (3-4), and use the blower to discharge the detached coking product residue from the discharge valve (3-5) to achieve the effect of cleaning the inside of the device.

4. The method according to claim 2, characterized in that, In step (1), the particle size of the waste catalyst is 50 nm to 500 μm.

5. The method according to claim 2, characterized in that, The flow rates of the precursor gas in steps (3) and (7) and the water vapor in step (10) are 1 to 100 slm.

6. The method according to claim 2, characterized in that, The AC high voltage applied in steps (3), (7) and (10) ensures an output power of 10 to 1000W to generate a stable plasma discharge; after stopping the oxygen supply in step (5), argon gas is supplied for 2 to 3 minutes at the same flow rate as in step (3); the waste catalyst is circulated 5 to 10 times in steps (5) and (9).

7. The method according to claim 2, characterized in that, The water vapor plasma treatment time in step (10) is 3 to 6 minutes.

8. The method according to claim 2, characterized in that, The outer wall insulation material of the plasma fluidized bed is high-temperature resistant inorganic materials such as quartz and ceramics, or high-temperature resistant polymer materials such as polytetrafluoroethylene, polyphenylene sulfide, polyether ether ketone, polyphenylene ester and polyphenylene ether. The plasma fluidized bed is in the form of dielectric barrier discharge.

9. The method according to claim 2, characterized in that, The waste gas from the waste gas treatment device A (13-1) is introduced into the alkali tank to remove sulfides from the gas; the waste gas from the waste gas treatment device B (13-2) is ignited to remove hydrogen from the gas.

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