Regeneration treatment method of high-arsenic-content inactivated SCR (Selective Catalytic Reduction) denitration catalyst
Through a multi-step regeneration treatment method, including photocatalysis and ion exchange, washing and drying, loading and calcining of active ingredients, the problem of difficult arsenate in SCR denitrification catalysts is successfully solved, and efficient arsenic removal and catalyst activity recovery are achieved.
Patent Information
- Application Number
- CN202411886195.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-03-21
AI Technical Summary
The prior art is difficult to effectively remove arsenic oxide and arsenate in SCR denitrification catalysts with high arsenic content, resulting in the inability to recover the catalyst activity.
The regeneration treatment method is adopted in steps such as pretreatment, photocatalysis and ion exchange, washing and drying, active ingredient loading, secondary drying and calcining. The method includes ion exchange with Zn-Fe-Si catalyst and FePO4 solution under ultraviolet light, washing with alkali and acid solutions, loading and calculating of active ingredients to remove arsenate in the catalyst.
The efficient removal of arsenate in SCR denitrification catalysts with high arsenic-containing inactivated SCR denitrification catalysts is achieved. The arsenic removal rate can reach more than 99%, and the catalyst activity is restored to more than 95%, which extends the service life of the catalyst and reduces operating costs.
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalyst regeneration, and in particular to a regeneration method for a highly arsenic-containing deactivated SCR denitration catalyst. Background Art
[0002] During operation, the activity of SCR denitration catalysts will gradually decrease due to the adsorption of toxic components such as alkali metals, alkaline earth metals, and heavy metals in the flue gas, and eventually they will not be able to meet the denitration requirements and need to be regenerated or recycled. However, there is still no good regeneration technology for deactivated SCR denitration catalysts with high arsenic content, especially deactivated catalysts with arsenic content higher than 3% are often directly recycled as non-renewable waste.
[0003] The flue gas produced by burning high-arsenic coal has a high arsenic content. When the SCR denitrification catalyst is running in it, a large amount of arsenic components will accumulate rapidly, and the arsenic content can even exceed 8wt%. When arsenic accumulates rapidly and in large quantities on the catalyst, in addition to covering the surface and internal pores of the catalyst in the form of oxides, a large amount of arsenic will also react with the active component V2O5 and active additives WO3, MoO3, etc. of the catalyst to generate complex arsenates, which gradually deactivates the catalyst. The regeneration of this type of arsenic-poisoned catalyst has difficulties such as the difficulty in removing arsenic in the arsenate and the incomplete removal of arsenic due to excessive arsenic content. At present, the regeneration process of arsenic-poisoned catalysts proposed in China is mainly aimed at poisoned catalysts with an arsenic content of less than 2wt%. The core steps are mainly high-temperature alkali solution cleaning and reduction roasting. The above methods only have a certain removal effect on arsenic oxides in low-content arsenic-poisoned catalysts, and have almost no effect on the removal of arsenate components, resulting in a large amount of arsenic in the regenerated catalyst, and the catalyst activity cannot be restored. Summary of the invention
[0004] The invention provides a regeneration method for a high-arsenic-containing deactivated SCR denitration catalyst, which solves the technical problem that arsenic oxide and arsenate in a deactivated SCR denitration catalyst with an arsenic content greater than 8wt% cannot be effectively removed simultaneously.
[0005] The present invention adopts the following technical solution: a regeneration method for a high-arsenic-containing deactivated SCR denitration catalyst, comprising the following steps:
[0006] (1) Pretreatment: After the deactivated SCR denitration catalyst is cleaned by soot blowing, ultrasonic acid washing is performed for 20-30 minutes;
[0007] (2) Photocatalysis and ion exchange: The pretreated SCR denitration catalyst is placed in an ion exchange solution containing a photocatalyst at a wavelength of 315-400nm and a light source intensity of >100μW / cm 2The photocatalyst is a Zn-Fe-Si catalyst and the ion exchange liquid is a FePO4 solution;
[0008] (3) washing and drying: soaking the catalyst treated in step (2) in an alkaline solution and an acid solution for 20-25 min, then repeatedly rinsing with deionized water for several times, and drying;
[0009] (5) Active ingredient loading: immersing the catalyst treated in step (3) into an ammonium metavanadate solution to complete the loading of the active ingredient vanadium;
[0010] (6) Secondary drying and calcination: The catalyst is dried again at a temperature of 80-90°C. After drying, the catalyst is calcined at a temperature of 450-480°C for 3-3.5 hours.
[0011] Furthermore, in step (1), the acid solution is an oxalic acid solution with a mass concentration of 1-5 g / L, the ultrasonic intensity is 50-80 KHz, and the ultrasonic time is 20-30 min.
[0012] Furthermore, in the step (2), the content of the Zn-Fe-Si catalyst is 0.2-0.5 g / L, the mass concentration of the FePO4 solution is 2-5 g / L, and the volume ratio of the FePO4 solution to the Zn-Fe-Si catalyst is 25-40:1.
[0013] Furthermore, the Zn-Fe-Si catalyst is prepared by a co-precipitation method, wherein the mass ratio of ZnO:Fe2O3:SiO2 is 2:1:5.
[0014] Furthermore, in the step (3), the alkaline solution is a sodium hydroxide solution with a mass concentration of 15 to 25 g / L, the acid solution is a sulfuric acid solution with a mass concentration of 2 to 5 g / L, and the alkaline washing temperature is 45-55°C.
[0015] Furthermore, in step (3), the drying temperature is 80-90° C., and the moisture content of the catalyst after drying is less than 5%.
[0016] Furthermore, in step (4), the concentration of the ammonium metavanadate solution is 20-25 g / L, and the volume ratio of the ammonium metavanadate solution to the catalyst is 8-10:1.
[0017] The beneficial effects of the present invention are:
[0018] (1) The treatment method of the present invention has simple steps and is easy to operate. It is suitable for regenerating deactivated SCR denitration catalysts with an arsenic content of more than 8 wt%. By adding a photocatalyst and an ion exchange liquid, the arsenate in the catalyst is exchanged with the phosphate in the solution and enters the solution, so that the arsenate in the catalyst is converted into phosphate with denitration activity, and the arsenic component in the catalyst is removed without losing the active components of the catalyst.
[0019] (2) The regeneration method of the present invention has low energy consumption and low overall regeneration process cost. The moisture content of the catalyst is controlled before calcination, thereby retaining the mechanical strength of the catalyst. The regeneration of the deactivated catalyst is completed through the supplementation of active ingredients and the drying and calcination steps. The regenerated catalyst not only has good chemical activity, but also has excellent mechanical properties.
[0020] (3) By adopting the regeneration process of the present invention, the arsenic removal rate of the poisoned catalyst with an arsenic content of 8wt% can reach more than 99%, the arsenic content in the catalyst after regeneration is less than 50ppm, and the denitrification activity can be restored to more than 95% of the same active formula, so that the service life of the SCR denitrification catalyst in high arsenic flue gas is greatly extended, and the catalyst user saves a considerable amount of SCR denitrification system operating costs. DETAILED DESCRIPTION
[0021] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.
[0022] Embodiment 1:
[0023] A regeneration method for a high-arsenic deactivated SCR denitration catalyst comprises the following steps:
[0024] (1) Pretreatment: First, use compressed air to blow away the loose dust on the catalyst surface, and then use a water gun to further clean it until there is no obvious dust on the catalyst surface. Then, the deashed catalyst is placed in an oxalic acid solution with a concentration of 1g / L and ultrasonically pickled for 20min;
[0025] (2) Ion exchange: The acid-washed catalyst was placed in a 2 g / L FePO4 solution, and a Zn-Fe-Si catalyst was added to the solution at a concentration of 0.2 g / L. The solution was then heated at a wavelength of 315-400 nm and 100 μW / cm 2 UV irradiation for 8 hours;
[0026] (3) Washing and drying: First, high-temperature alkaline washing is performed, with a temperature of 45°C and a concentration of 15 g / L NaOH solution, and the catalyst is placed in the alkaline solution and soaked for 20 min; then acid washing and water washing are performed, and after the catalyst is alkaline washed, it is acid washed with a 2 g / L dilute H2SO4 solution and washed with deionized water several times in sequence, and the washed catalyst is dried at 80°C for 40 min. After drying, the moisture content of the catalyst is 2.1%;
[0027] (4) Active ingredient loading: Prepare a 20 g / L ammonium metavanadate solution, immerse the catalyst in the solution for 30 seconds, and then take out the catalyst.
[0028] (5) Secondary drying and calcination: First, the catalyst was dried at 80°C for 25 min. After drying, the moisture content of the catalyst was 3.8%. The catalyst was then calcined at 480°C for 3 h to complete the regeneration of the catalyst.
[0029] Through the above regeneration process, the arsenic content in the catalyst after regeneration is 12 ppm, and the arsenic removal rate is close to 100%.
[0030] Embodiment 2:
[0031] A regeneration method for a high-arsenic deactivated SCR denitration catalyst comprises the following steps:
[0032] (1) Pretreatment: First, use compressed air to blow away the loose dust on the catalyst surface, and then use a water gun to further clean it until there is no obvious dust on the catalyst surface. The deashed catalyst is placed in an oxalic acid solution with a concentration of 5g / L and ultrasonically pickled for 30min;
[0033] (2) Ion exchange: The acid-washed catalyst was placed in a 5 g / L FePO4 solution, and a Zn-Fe-Si catalyst was added to the solution at a concentration of 0.5 g / L. The solution was then heated at a wavelength of 315-400 nm and 100 μW / cm 2 UV irradiation for 12 hours;
[0034] (3) Washing and drying: Prepare a 25 g / L NaOH solution at 55°C, soak the catalyst in the solution for 5 min, acid wash and water wash, and then alkaline wash the catalyst and then acid wash and water wash with a 5 g / L dilute H2SO4 solution. Dry the washed catalyst at 90°C for 30 min. After drying, the moisture content of the catalyst is 2.5%;
[0035] (4) Active ingredient loading: prepare a 20 g / L ammonium metavanadate solution, immerse the catalyst in the solution for 30 s, and then take out the catalyst;
[0036] (5) Secondary drying and calcination: First, the catalyst was dried at 90°C for 20 min. After drying, the moisture content of the catalyst was 3.1%. The catalyst was then calcined at 480°C for 3 h to complete the regeneration of the catalyst.
[0037] Through the above regeneration process, the arsenic content in the catalyst after regeneration is 37 ppm, and the arsenic removal rate is close to 100%.
[0038] Embodiment 3:
[0039] A regeneration method for a high-arsenic deactivated SCR denitration catalyst comprises the following steps:
[0040] (1) Pretreatment: First, use compressed air to blow away the loose dust on the catalyst surface, and then use a water gun to further clean it until there is no obvious dust on the catalyst surface. Ultrasonic acid washing: The deashed catalyst is placed in a 3g / L oxalic acid solution and ultrasonically acid washed for 10 minutes;
[0041] (2) Ion exchange: The acid-washed catalyst was placed in a 3 g / L FePO4 solution, and a Zn-Fe-Si catalyst was added to the solution at a concentration of 0.3 g / L. The solution was then heated at a wavelength of 315-400 nm and 100 μW / cm 2 UV irradiation for 10 hours;
[0042] (3) Washing and drying: prepare a 20 g / L NaOH solution at 50°C, and soak the catalyst in the solution for 10 min. Acid washing and water washing: After the catalyst is alkaline washed, it is then acid washed with a 3 g / L dilute H2SO4 solution and then washed with water; the washed catalyst is dried at 85°C for 35 min, and the moisture content of the catalyst after drying is 2.9%;
[0043] (4) Active ingredient loading: prepare a 20 g / L ammonium metavanadate solution, immerse the catalyst in the solution for 30 s, and then take out the catalyst;
[0044] (5) Secondary drying and calcination: First, the catalyst was dried at 85°C for 25 min. After drying, the moisture content of the catalyst was 2.7%. The catalyst was then calcined at 480°C for 3 h to complete the regeneration of the catalyst.
[0045] Through the above regeneration process, the arsenic content in the catalyst after regeneration is 24 ppm, and the arsenic removal rate is close to 100%.
[0046] Embodiment 4:
[0047] A regeneration method for a high-arsenic deactivated SCR denitration catalyst comprises the following steps:
[0048] (1) Pretreatment: First, use compressed air to blow away the loose dust on the catalyst surface, and then use a water gun to further clean it until there is no obvious dust on the catalyst surface. Ultrasonic acid washing: The deashed catalyst is placed in an oxalic acid solution with a concentration of 4g / L and ultrasonically acid washed for 8min;
[0049] (2) Ion exchange: The acid-washed catalyst was placed in a 4 g / L FePO4 solution, and a Zn-Fe-Si catalyst was added to the solution at a concentration of 0.35 g / L. The solution was then heated at a wavelength of 315-400 nm and 100 μW / cm 2 UV irradiation for 11 hours;
[0050] (3) Washing and drying: Prepare a 18 g / L NaOH solution at 55°C, soak the catalyst in the solution for 20 min, and then perform an alkali wash on the catalyst, followed by an acid wash with a 2.5 g / L dilute H2SO4 solution and a water wash; dry the washed catalyst at 90°C for 30 min, and the moisture content of the catalyst after drying is 3.2%;
[0051] (4) Active ingredient loading: prepare a 20 g / L ammonium metavanadate solution, immerse the catalyst in the solution for 30 s, and then take out the catalyst;
[0052] (5) Secondary drying and calcination: First, the catalyst was dried at 90°C for 30 min. After drying, the moisture content of the catalyst was 1.9%. The catalyst was then calcined at 480°C for 3 h to complete the regeneration of the catalyst.
[0053] Through the above regeneration process, the arsenic content in the catalyst after regeneration is 42 ppm, and the arsenic removal rate is close to 100%.
[0054] Fresh catalyst and the catalysts regenerated from Examples 1 to 4 were used to test the denitration performance. The test conditions were: NOx concentration was 350 mg / m 3 , SO2 concentration is 1200mg / m 3 , O2 concentration is 5%, H2O concentration is 8%, ammonia nitrogen ratio is 1, and the air velocity is 15000h -1 , the temperature is 250℃ and 300℃. The test results of denitrification efficiency of regenerated catalyst and fresh catalyst are shown in Table 1.
[0055] Table 1 Denitrification performance test results of regenerated catalyst and fresh catalyst
[0056] catalyst 250℃ Denitrification efficiency / % 300℃ denitrification efficiency / % Fresh 75.32 90.23 Example 1 73.12 88.12 Example 2 72.99 88.07 Example 3 72.85 87.89 Example 4 73.34 87.56
[0057] It can be seen from Table 1 that under the two test temperature conditions, the denitration efficiency of the regenerated catalyst is close to that of the fresh catalyst, and the difference in denitration efficiency between the regenerated catalyst and the fresh catalyst does not exceed 3%, indicating that the regenerated catalyst also has a high denitration activity.
Claims
1. A regeneration method for a high-arsenic deactivated SCR denitration catalyst, characterized in that: The steps include: (1) Pretreatment: After the deactivated SCR denitration catalyst to be treated is cleaned by soot blowing, it is ultrasonically pickled; (2) Photocatalysis and ion exchange: The pretreated SCR denitration catalyst is placed in an ion exchange solution containing a photocatalyst at a wavelength of 315-400nm and a light source intensity of >100μW / cm 2 The photocatalyst is a Zn-Fe-Si catalyst and the ion exchange liquid is a FePO4 solution; (3) washing and drying: soaking the catalyst treated in step (2) in an alkaline solution and an acid solution for 20-25 min, then repeatedly rinsing with deionized water for several times, and drying; (4) Active ingredient loading: immersing the catalyst treated in step (3) into an ammonium metavanadate solution to complete the loading of the active ingredient vanadium; (5) Secondary drying and calcination: The catalyst is dried again at a temperature of 80-90°C. After drying, the catalyst is calcined at a temperature of 450-480°C for 3-3.5 hours.
2. The regeneration method of a high arsenic-containing deactivated SCR denitration catalyst according to claim 1, characterized in that: In the step (1), the acid solution is an oxalic acid solution with a mass concentration of 1-5 g / L, the ultrasonic intensity is 50-80 KHz, and the ultrasonic time is 20-30 min.
3. The regeneration method of a high arsenic-containing deactivated SCR denitration catalyst according to claim 1, characterized in that: The content of the Zn-Fe-Si catalyst in the step (2) is 0.2-0.5 g / L, the mass concentration of the FePO4 solution is 2-5 g / L, and the volume ratio of the FePO4 solution to the Zn-Fe-Si catalyst is 25-40:
1.
4. The regeneration method of a high arsenic-containing deactivated SCR denitration catalyst according to claim 3, characterized in that: The Zn-Fe-Si catalyst is prepared by a co-precipitation method, wherein the mass ratio of ZnO:Fe2O3:SiO2 is 2:1:
5.
5. The regeneration method of a high arsenic-containing deactivated SCR denitration catalyst according to claim 1, characterized in that: In the step (3), the alkaline solution is a sodium hydroxide solution with a mass concentration of 15-25 g / L, the acid solution is a sulfuric acid solution with a mass concentration of 2-5 g / L, and the temperature during the alkaline washing is 45-55°C.
6. The regeneration method of a high arsenic-containing deactivated SCR denitration catalyst according to claim 1, characterized in that: The drying temperature in step (3) is 80-90° C., and the moisture content of the catalyst after drying is less than 5%.
7. The regeneration method of a high arsenic-containing deactivated SCR denitration catalyst according to claim 1, characterized in that: In the step (4), the concentration of the ammonium metavanadate solution is 20-25 g / L, and the volume ratio of the ammonium metavanadate solution to the catalyst is 8-10:1.