A method for regenerating arsenic-poisoned vanadium-based SCR denitration catalyst by using hydrogen plasma

Abstract

The application discloses a method for regenerating arsenic-poisoned vanadium-based SCR (Selective Catalytic Reduction) denitration catalyst by using hydrogen plasma, and belongs to the technical field of poisoned catalyst regeneration and preparation, in particular to a method for regenerating arsenic-poisoned vanadium-based SCR denitration catalyst by using hydrogen plasma. The method can make arsenic in waste catalysts to be separated from the catalysts by selectively reacting hydrogen plasma with arsenic under mild conditions, form hydrogenated arsenic and further decompose into metallic arsenic, so that the catalysts and the metallic arsenic can be simultaneously recycled as resources. The method can also improve the intrinsic activity of the catalysts by regulating the aggregation mode of the active component vanadium on the catalyst surface. Therefore, the method can solve the contradiction between poison removal and active component reservation, and the activity of the regenerated catalyst is higher than that of a fresh catalyst. The method can also be extended to the modification and improvement of fresh vanadium-based catalysts.

Description

Technical Field

[0001] This invention belongs to the field of regeneration and preparation technology of poisoned catalysts, specifically relating to a method for regenerating arsenic-poisoned vanadium-based SCR denitration catalysts using hydrogen plasma treatment. Background Technology

[0002] Currently, the regeneration technology for arsenic-poisoned denitrification catalysts mainly relies on liquid-phase washing. However, this method has stringent requirements for the regeneration pH environment and suffers from low heavy metal removal rates, while also resulting in the loss of a significant amount of the active ingredient, vanadium oxide. Furthermore, this method leads to subsequent wastewater treatment issues containing heavy metals, resulting in substantial energy and economic consumption. Therefore, there is an urgent need for a regeneration technology for arsenic-poisoned denitrification catalysts under mild conditions to achieve resource recovery of arsenic and extend the catalyst's lifespan. Summary of the Invention

[0003] The present invention aims to solve the above-mentioned technical problems by providing a method for regenerating arsenic-poisoned vanadium-based SCR denitration catalysts using hydrogen plasma treatment.

[0004] The method of the present invention for regenerating arsenic-poisoned vanadium-based SCR denitration catalyst using hydrogen plasma is carried out according to the following steps:

[0005] 1. Place the arsenic-poisoned vanadium-based SCR denitration catalyst in a corundum boat, and then place the corundum boat in a plasma processing chamber; set the induction coil on the outer wall of the plasma processing chamber;

[0006] 2. Hydrogen and argon are simultaneously introduced into the plasma processing chamber to purge the air. The volume percentage of hydrogen in the hydrogen-argon mixture is 10% to 40%. Then, a vacuum pump is used to evacuate the pressure in the chamber to 10 Pa to 20 Pa. A radio frequency power supply is used to apply 500 W to 1000 W of power to the plasma on the induction coil. The processing time is 30 s to 90 s.

[0007] 3. Repeat step 2 2 to 8 times to obtain the plasma-treated vanadium-based SCR denitration catalyst.

[0008] Fourth, place the plasma-treated vanadium-based SCR denitration catalyst from step three into a muffle furnace and calcine it at 500℃~510℃ for 3h~3.5h, with a heating rate of 2℃ / min~5℃ / min, to obtain the regenerated vanadium-based SCR denitration catalyst.

[0009] This invention utilizes hydrogen plasma under mild conditions to selectively react with arsenic, enabling the arsenic in spent catalysts to detach from the catalyst, forming arsenic hydride, which further decomposes into metallic arsenic, thus achieving simultaneous resource recovery of both the catalyst and metallic arsenic. The method also enhances the intrinsic activity of the catalyst by controlling the aggregation morphology of the vanadium active component on the catalyst surface. Therefore, this invention resolves the contradiction between poison removal and active component retention, and the regenerated catalyst exhibits higher activity than the fresh catalyst. This invention can also be extended to the modification and enhancement of fresh vanadium-based catalysts, and can be used for the efficient regeneration of heavy metal-poisoned catalysts generated during denitrification processes in industries such as steel, building materials, and waste incineration, as well as for improving the performance of fresh catalysts.

[0010] Technical effects of the present invention:

[0011] 1. This invention can achieve arsenic removal (arsenic removal rate > 99%) while retaining the active component (retention rate of active component vanadium oxide > 99%) under mild conditions;

[0012] 2. This invention does not require subsequent water treatment and active component implantation processes. The method is relatively simple and practical, and can solve the problems of environmental pollution, high energy consumption, and high cost of traditional regeneration processes.

[0013] 3. This invention can achieve the aggregation of the active component vanadium, so that the conversion frequency of NO per unit vanadium site is 1.6 to 2.4 times that of fresh catalyst. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the principle of the present invention, in which the white sphere is titanium dioxide, the catalyst support;

[0015] Figure 2 The images are high-angle annular dark-field images of the catalyst before and after hydrogen plasma treatment in Experiment 1. Detailed Implementation

[0016] Specific Implementation Method 1: This implementation method is a method for regenerating arsenic-poisoned vanadium-based SCR denitration catalysts using hydrogen plasma treatment, specifically carried out according to the following steps:

[0017] 1. Place the arsenic-poisoned vanadium-based SCR denitration catalyst in a corundum boat, and then place the corundum boat in a plasma processing chamber; set the induction coil on the outer wall of the plasma processing chamber;

[0018] 2. Hydrogen and argon are simultaneously introduced into the plasma processing chamber to purge the air. The volume percentage of hydrogen in the hydrogen-argon mixture is 10% to 40%. Then, a vacuum pump is used to evacuate the pressure in the chamber to 10 Pa to 20 Pa. A radio frequency power supply is used to apply 500 W to 1000 W of power to the plasma on the induction coil. The processing time is 30 s to 90 s.

[0019] 3. Repeat step 2 2 to 8 times to obtain the plasma-treated vanadium-based SCR denitration catalyst.

[0020] Fourth, place the plasma-treated vanadium-based SCR denitration catalyst from step three into a muffle furnace and calcine it at 500℃~510℃ for 3h~3.5h, with a heating rate of 2℃ / min~5℃ / min, to obtain the regenerated vanadium-based SCR denitration catalyst.

[0021] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the number of turns of the induction coil mentioned in step one is 4 to 10. Everything else is the same as in Specific Implementation Method One.

[0022] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the processing time in step two is 30 seconds. Everything else is the same as in Specific Implementation Method One or Two.

[0023] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the frequency of the radio frequency power supply mentioned in step two is 13.56MHz to 40.68MHz. Everything else is the same as in Specific Implementation Methods One to Three.

[0024] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that: in step four, the calcination is carried out at 500℃ for 3 hours, with a heating rate of 2℃ / min. Everything else is the same as in Specific Implementation Method Four.

[0025] The invention was verified using the following experiments:

[0026] Experiment 1: This experiment demonstrates a method for regenerating arsenic-poisoned vanadium-based SCR denitration catalysts using hydrogen plasma treatment. The specific steps are as follows:

[0027] 1. Place the arsenic-poisoned vanadium-tungsten / titanium SCR denitration catalyst (arsenic content 3.66 wt%) in an alumina boat, and place the alumina boat in an inductively coupled plasma processing chamber; set the induction coil on the outer wall of the plasma processing chamber; the induction coil has 10 turns;

[0028] 2. Hydrogen and argon are simultaneously introduced into the plasma processing chamber to purge the air. Then, a vacuum pump is used to evacuate the chamber to a pressure of 10 Pa. The volume percentage of hydrogen in the hydrogen-argon mixture is 20%. A radio frequency power supply is used to apply 500 W of power to the plasma on the induction coil. The processing time is 30 s.

[0029] 3. Repeat step 2 8 times to obtain the plasma-treated vanadium-based SCR denitration catalyst.

[0030] Fourth, place the plasma-treated vanadium-based SCR denitration catalyst from step three into a muffle furnace and calcine it at 500℃ for 3 hours with a heating rate of 2℃ / min to obtain the regenerated vanadium-based SCR denitration catalyst.

[0031] The regenerated vanadium-based SCR denitration catalyst obtained in Experiment 1 was placed in an NH3-SCR activity testing system to test its NO conversion rate. The results showed that the NO conversion frequency per unit vanadium site of the regenerated vanadium-based SCR denitration catalyst was 46.5 × 10⁻⁶. -3 s -1 ) is a fresh vanadium-based SCR denitration catalyst (25.7×10 -3 s -1 It is 1.8 times that of arsenic-poisoned vanadium-tungsten / titanium SCR denitration catalysts (6.2 × 10⁻⁶). -3 s -1 The arsenic content in the regenerated vanadium-based SCR denitrification catalyst obtained in Experiment 1 was 7.5 times that of the standard catalyst. ICP-MS measurements showed that the arsenic content was only 0.02 wt%, which is below the instrument's detection limit, thus proving that the arsenic was completely removed.

[0032] SCR denitrification catalyst composition in Experiment 1

[0033]

[0034] Figure 2 The images are high-angle annular dark-field scanning transmission electron microscope images of the arsenic-poisoned vanadium-tungsten / titanium SCR denitration catalysts (a and b) before hydrogen plasma treatment and the regenerated vanadium-based SCR denitration catalysts (c and d) after treatment. The white bright spots are vanadium atoms on the catalyst surface. It can be seen from the images that the vanadium atoms on the catalyst surface were in a dispersed state before hydrogen plasma treatment, and the vanadium on the catalyst surface was aggregated after hydrogen plasma treatment.

[0035] Experiment 2: This experiment differs from Experiment 1 in that, in step one, the arsenic-poisoned vanadium-molybdenum / titanium SCR denitration catalyst was placed in a corundum boat. Everything else is the same as Experiment 1.

[0036] The regenerated vanadium-based SCR denitrification catalyst obtained in Experiment 2 was placed in an NH3-SCR activity testing system to test its NO conversion rate. The results showed that the NO conversion frequency per unit vanadium site of the regenerated vanadium-based SCR denitrification catalyst was 1.6 times that of the fresh vanadium-based SCR denitrification catalyst. ICP-MS analysis revealed that the arsenic content in the regenerated vanadium-based SCR denitrification catalyst obtained in Experiment 2 was only 0.03 wt%, which was below the instrument detection limit, thus proving that arsenic was completely removed.

[0037] SCR denitrification catalyst composition in Experiment 2

[0038]

[0039] Experiment 3: This experiment describes a method for modifying and improving fresh vanadium-based catalysts, as detailed below:

[0040] 1. Place the fresh vanadium-tungsten / titanium SCR denitration catalyst in an alumina boat, and place the alumina boat in an inductively coupled plasma processing chamber; set the induction coil on the outer wall of the plasma processing chamber; the induction coil has 10 turns;

[0041] 2. Hydrogen and argon are simultaneously introduced into the plasma processing chamber, and the pressure in the chamber is then evacuated to 10 Pa using a vacuum pump. The volume percentage of hydrogen in the hydrogen-argon mixture is 20%. A radio frequency power supply is used to apply 500 W of power to the plasma on the induction coil, and the processing time is 30 s.

[0042] 3. Repeat step 2 three times to obtain the plasma-treated vanadium-based SCR denitration catalyst.

[0043] Fourth, place the plasma-treated vanadium-based SCR denitration catalyst from step three into a muffle furnace and calcine it at 500℃ for 3 hours with a heating rate of 2℃ / min to obtain the regenerated vanadium-based SCR denitration catalyst.

[0044] The regenerated vanadium-based SCR denitration catalyst obtained in Experiment 3 was placed in an NH3-SCR activity testing system to test its NO conversion rate. The results showed that the conversion frequency of NO per unit vanadium site of the regenerated vanadium-based SCR denitration catalyst was 2.4 times that of the fresh vanadium-based SCR denitration catalyst.

Claims

1. A method for regenerating arsenic-poisoned vanadium-based SCR denitration catalysts using hydrogen plasma treatment, characterized in that... The method for regenerating arsenic-poisoned vanadium-based SCR denitration catalysts using hydrogen plasma is carried out according to the following steps:

1. Place the arsenic-poisoned vanadium-based SCR denitration catalyst in a corundum boat, and then place the corundum boat in a plasma processing chamber; set the induction coil on the outer wall of the plasma processing chamber; 2. Hydrogen and argon are simultaneously introduced into the plasma processing chamber to purge the air. The volume percentage of hydrogen in the hydrogen-argon mixture is 10% to 40%. Then, a vacuum pump is used to evacuate the pressure in the chamber to 10 Pa to 20 Pa. A radio frequency power supply is used to apply 500 W to 1000 W of power to the plasma on the induction coil. The processing time is 30 s to 90 s. The frequency of the radio frequency power supply mentioned in step two is 13.56MHz~40.68MHz; 3. Repeat step 2 2 to 8 times to obtain the plasma-treated vanadium-based SCR denitration catalyst. Fourth, place the plasma-treated vanadium-based SCR denitration catalyst from step three into a muffle furnace and calcine it at 500℃~510℃ for 3h~3.5h, with a heating rate of 2℃ / min~5℃ / min, to obtain the regenerated vanadium-based SCR denitration catalyst.

2. The method for regenerating arsenic-poisoned vanadium-based SCR denitration catalyst using hydrogen plasma according to claim 1, characterized in that... The number of turns of the induction coil mentioned in step one is 4 to 10.

3. The method for regenerating arsenic-poisoned vanadium-based SCR denitration catalyst using hydrogen plasma according to claim 1, characterized in that... The processing time in step two is 30 seconds.

4. The method for regenerating arsenic-poisoned vanadium-based SCR denitration catalyst using hydrogen plasma according to claim 1, characterized in that... In step four, the food is calcined at 500℃ for 3 hours, with a heating rate of 2℃ / min.

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