A stepwise regeneration method for denitrification catalysts in raw materials

Abstract

This invention discloses a step-by-step regeneration method for a raw denitrification catalyst, comprising the following steps: pre-cleaning the catalyst to remove accumulated dust on and inside the catalyst surface; then performing step-by-step cleaning with at least three different agents; followed by water washing, drying, and cooling. The step-by-step regeneration method for raw denitrification catalysts provided by this invention uses three different agents for step-by-step cleaning, enabling full-process regeneration of deactivated catalysts. A universal agent A is used for surface cleaning, B for detailed cleaning, and C for activation cleaning. This method primarily removes residual active components from the catalyst, offering versatility and enabling deep regeneration of commonly available deactivated catalysts to the raw material level. It removes most impurities and active components while preserving the main structure of the catalyst support. The treated catalyst can be reloaded with a fixed amount of active components. The process is simple, low-cost, and suitable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of catalyst regeneration technology, specifically relating to a stepwise regeneration method for a white carbon denitration catalyst. Background Technology

[0002] In recent years, with the implementation of ultra-low emission policies in the power and non-power sectors, SCR denitrification technology has been widely applied in thermal power, glass, cement, sludge co-firing, and biomass incineration. As a core component of the denitrification process, the SCR denitrification catalyst is prone to deactivation after prolonged operation. After deactivation, catalysts with good mechanical strength and no special chemical pollution can be regenerated and reused; however, severely damaged catalysts or those with high levels of heavy metals such as arsenic and mercury are not worth regenerating. Catalyst poisoning is multifaceted and complex, making it difficult to restore catalyst activity after deactivation.

[0003] Conventional regeneration methods involve targeted cleaning based on specific project characteristics and catalyst conditions. After removing conventional surface contaminants, the active components of the catalyst are preserved as much as possible through reagent formulation design to reduce the difficulty and cost of subsequent loading. However, in recent years, the volume of old catalysts has been increasing, leading to situations where catalysts from different plants are being optimized and blended. Therefore, it is necessary to develop a universal regeneration method for denitrification catalysts made from raw materials.

[0004] In conventional designs, different concentrations of active components need to be customized according to the specific needs of power plants or non-power industries. After normal regeneration, the small amount of active components lost during the cleaning process needs to be replenished as required. However, substituting catalysts with different active component contents for each other places high demands on the loading process. If it is possible to clean the catalyst blank, remove all active components, and retain only the main catalyst support structure, it is possible to quickly implement customized active component loading concentration requirements. The active components removed from the wastewater during regeneration can also be extracted and reused. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the present invention aims to provide a method for the stepwise regeneration of a denitrification catalyst in a raw material.

[0006] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows:

[0007] A method for staged regeneration of a denitrification catalyst from a raw material includes the following steps:

[0008] The catalyst is pre-cleaned to remove dust from its surface and interior. Then, it is cleaned step by step with at least three different agents, followed by water washing, drying, and cooling.

[0009] Furthermore, the method uses three different cleaning agents for step-by-step cleaning, namely, universal agent A, universal agent B, and universal agent C. The steps of the method using three different cleaning agents for step-by-step cleaning include:

[0010] (1) Surface cleaning: The catalyst is completely immersed in the universal reagent A and cleaned by bubbling agitation with compressed air at a temperature of 50-60℃.

[0011] (2) Detailed cleaning: Immerse the catalyst cleaned with general agent A completely in the prepared general agent B, with the agent level above the catalyst surface, and clean the catalyst for 60-120 minutes by bubbling with compressed air.

[0012] (3) Activation cleaning: Transfer the catalyst to an ultrasonic tank containing a prepared universal reagent C, with the reagent level above the catalyst surface, and turn on the ultrasonic waves to perform a thorough cleaning for 10-60 minutes.

[0013] Furthermore, the universal reagent A is a weakly alkaline soaking solution, prepared from the following raw materials by weight percentage: 0.1-3% sodium hydroxide, 0.1-2% sodium phosphate, and the balance being deionized water. The preparation method of the universal reagent A includes the following steps:

[0014] At 50-60℃, add 0.1-3% sodium hydroxide and 0.1-2% sodium phosphate to deionized water and mix well to obtain the desired reagent.

[0015] Furthermore, the preparation method of the universal drug B includes the following steps:

[0016] Add 0.2-5 wt% aminosulfonic acid, 0.1-1 wt% hydrochloric acid, 0.1-1 wt% nitric acid, 0.3-3% ammonium fluoride, and 0.1-1 wt% ethylene oxide condensate to deionized water, stir evenly at room temperature, and let stand to obtain the desired reagent.

[0017] When using general-purpose agent B, the temperature should be maintained at 20-30℃.

[0018] Furthermore, the preparation method of the universal drug C includes the following steps:

[0019] Add 0.5-4 wt% oxalic acid, 0.2-0.5 wt% sulfuric acid, and 0.01-0.1 wt% glycolic acid to deionized water, and stir until homogeneous at room temperature.

[0020] When using general-purpose agent C, a temperature of 30-40℃ must be maintained.

[0021] Furthermore, the water washing includes the following steps:

[0022] Transfer the catalyst to a clean water tank, ensuring the water level is above the catalyst surface. Rinse with clean water by bubbling for 20-50 minutes to remove surface residue.

[0023] Furthermore, the drying and cooling steps include:

[0024] The cleaned catalyst is pushed into the drying furnace, and the drying program is started. The drying heating rate does not exceed 7°C / minute. When the furnace is fully heated to 200-245°C, it is kept at that temperature for drying. Then, the temperature is lowered, and the cooling rate does not exceed 7°C / minute.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. Using three different agents for step-by-step cleaning, the deactivated catalyst can be regenerated throughout the entire process. Among them, the universal agent A is used for surface cleaning, which mainly removes substances such as silicon and aluminum from conventional dirt, while also removing a small amount of heavy metal poisoning. The universal agent B is used for detailed cleaning, and the universal agent C is used for activation cleaning, which mainly removes the residual active components in the catalyst.

[0027] 2. This method is versatile and can deeply regenerate commonly deactivated catalysts on the market to the point of being a blank. While retaining the main structure of the catalyst support, it removes most impurities and active components. The treated catalyst can be directly reloaded with a fixed amount of active components as needed. The process is simple, low-cost, and suitable for industrial promotion and use. Detailed Implementation

[0028] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0029] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0030] A method for staged regeneration of a denitrification catalyst from a raw material includes the following steps:

[0031] (1) Manually remove the floating dust on the outer surface of the catalyst frame and automatically remove the dust in the catalyst unit channel with compressed air.

[0032] (2) Use a high-pressure water gun with appropriate pressure to spray deionized water for initial cleaning. After automatic rinsing, manually rinse the catalyst with a high-pressure water gun to remove ash.

[0033] (3) Surface cleaning: Immerse the catalyst completely in general reagent A. Clean the catalyst for 60 minutes by bubbling with compressed air, while simultaneously bubbling with compressed air at the bottom of the cleaning tank to soften the dirt, at a temperature of 50-60℃.

[0034] (4) Detailed cleaning: Immerse the catalyst cleaned with universal reagent A completely in the prepared universal reagent B, with the reagent level above the catalyst surface, and clean the catalyst for 60-120 minutes by bubbling with compressed air.

[0035] (5) Activation cleaning: Transfer the catalyst to an ultrasonic tank containing a general reagent C, with the reagent level above the catalyst surface, and turn on the ultrasonic waves to perform a thorough cleaning for 10-60 minutes.

[0036] (6) Transfer the catalyst to a clean water tank, with the liquid level above the catalyst surface, and rinse with clean water by bubbling to remove surface residue for 20-50 minutes.

[0037] (7) Push the cleaned catalyst into the drying furnace, start the drying program, and the drying heating rate shall not exceed 7℃ / minute. When the furnace is fully heated to 200-245℃, keep it at the temperature for drying, and then cool it down. The cooling rate shall not exceed 7℃ / minute.

[0038] Universal Agent A is a weakly alkaline soaking solution, prepared from the following raw materials by weight percentage: sodium hydroxide 0.1-3%, sodium phosphate 0.1-2%, and the balance being deionized water.

[0039] The preparation method of universal drug A includes the following steps:

[0040] At 50-60℃, add 0.1-3% sodium hydroxide and 0.1-2% sodium phosphate to deionized water and mix well to obtain the desired reagent.

[0041] Universal Agent A provides an alkaline washing solution atmosphere, which mainly removes impurities such as silicon and aluminum from the surface and interior of the catalyst, and can partially dissolve the worm-like deposits of dirt in the micropores of the catalyst.

[0042] The preparation method of universal drug B includes the following steps:

[0043] Add 0.2-5 wt% aminosulfonic acid, 0.1-1 wt% hydrochloric acid, 0.1-1 wt% nitric acid, 0.3-3% ammonium fluoride, and 0.1-1 wt% ethylene oxide condensate to deionized water, stir evenly at room temperature, and let stand to obtain the desired reagent.

[0044] Among them, aminosulfonic acid, hydrochloric acid, and nitric acid serve as the main acid sources of the reagent, undergoing ion exchange with ammonium fluoride to replenish and remove impurities in the micropores; ethylene oxide condensate has good dispersibility, which makes it difficult for the scale stripped from the catalyst to agglomerate, maintains its dispersibility, and is more conducive to cleaning and removal, changes the contact performance of scale on the catalyst surface, and promotes the stripping and removal of scale on the pore surface.

[0045] When using general-purpose reagent B, a temperature of 20-30℃ should be maintained to promote better performance. During cleaning, gas should be introduced for bubbling to promote contact between the reagent and the catalyst, enhance solution fluidity, and accelerate the removal of catalyst residue. The temperature should not be too high to avoid acid fumes evaporating and causing harm to humans and polluting the environment.

[0046] The preparation method of universal drug C includes the following steps:

[0047] Add 0.5-4 wt% oxalic acid, 0.2-0.5 wt% sulfuric acid, and 0.01-0.1 wt% glycolic acid to deionized water and stir until homogeneous at room temperature.

[0048] Hydroxyacetic acid has ion chelating properties and can complex with various metal impurities, effectively removing alkali (earth) metal components from catalysts.

[0049] When using universal agent C, a temperature of 30-40℃ must be maintained, and an ultrasonic oscillation process should be used as an auxiliary method, with an ultrasonic frequency of 40Hz and an ultrasonic time of 10-60 minutes. Because the ultrasonic process generates heat, the water temperature must be kept from rising excessively.

[0050] Example 1

[0051] A method for staged regeneration of a denitrification catalyst from a raw material includes the following steps:

[0052] (1) Manually remove the floating dust on the outer surface of the catalyst frame and automatically remove the dust in the catalyst unit channel with compressed air.

[0053] (2) Use a high-pressure water gun with appropriate pressure to spray deionized water for initial cleaning. After automatic rinsing, manually rinse the catalyst with a high-pressure water gun to remove ash.

[0054] (3) Surface cleaning: The catalyst is completely immersed in the universal reagent A. The catalyst is cleaned for 60 minutes by bubbling with compressed air, while compressed air is used to bubble at the bottom of the cleaning tank to soften the dirt. The temperature is 56℃.

[0055] (4) Detailed cleaning: Immerse the catalyst cleaned with universal reagent A completely in the prepared universal reagent B, with the reagent level above the catalyst surface, and clean the catalyst for 100 minutes by bubbling with compressed air.

[0056] (5) Activation cleaning: Move the catalyst into an ultrasonic tank with the universal reagent C prepared, with the reagent level higher than the upper surface of the catalyst, and turn on the ultrasonic waves to perform a thorough cleaning for 30 minutes.

[0057] (6) Transfer the catalyst to a clean water tank, with the liquid level above the catalyst surface, and rinse with clean water by bubbling to remove surface residue for 20 minutes.

[0058] (7) Push the cleaned catalyst into the drying furnace, start the drying program, the drying heating rate is 4℃ / minute, and when the furnace is fully heated to 225℃, keep it at the temperature for drying, and then cool it down at a rate of 4℃ / minute.

[0059] In this embodiment, the universal reagent A is a weakly alkaline soaking solution, prepared from the following raw materials by weight percentage: 0.1% sodium hydroxide, 2% sodium phosphate, and the balance being deionized water. The preparation method of universal reagent A includes the following steps: at 55°C, 0.1% sodium hydroxide and 2% sodium phosphate are added to deionized water and mixed thoroughly.

[0060] Universal Reagent B is prepared from the following raw materials by weight percentage: 5 wt% aminosulfonic acid, 0.1 wt% hydrochloric acid, 0.1 wt% nitric acid, 0.3% ammonium fluoride, 0.1 wt% ethylene oxide condensate, and the balance being deionized water. The preparation method of Universal Reagent B includes the following steps: Add 5 wt% aminosulfonic acid, 0.1 wt% hydrochloric acid, 0.1 wt% nitric acid, 0.3% ammonium fluoride, and 0.1 wt% ethylene oxide condensate to deionized water, stir evenly at room temperature, and allow to stand to obtain the desired reagent. Universal Reagent B needs to be maintained at a temperature of 20-30℃ during use.

[0061] Universal Agent C is prepared from the following raw materials by weight percentage: 0.5 wt% oxalic acid, 0.5 wt% sulfuric acid, 0.1 wt% glycolic acid, and the balance being deionized water. The preparation method of Universal Agent C includes the following steps: Add 0.5 wt% oxalic acid, 0.5 wt% sulfuric acid, and 0.1 wt% glycolic acid to deionized water and stir until homogeneous at room temperature. During use, Universal Agent C needs to be maintained at a temperature of 30-40℃ and assisted by ultrasonic vibration at a frequency of 40 Hz for 30 minutes. Because the ultrasonic process generates heat, the water temperature must be kept from rising excessively.

[0062] Example 2

[0063] After three years of operation, the denitrification performance of the SCR denitrification system in a power plant decreased. A single catalyst sample was selected from the reactor; the sample had 18×18 pores and a length of 1180 mm. It was regenerated in the laboratory using the stepwise regeneration method of the present invention for the raw denitrification catalyst. Physicochemical analysis and activity testing were performed on the samples before and after regeneration. The results are as follows:

[0064] 1. Using a full-size Chinese-style test bench, the catalyst activity was measured to be 32 m / h before regeneration and recovered to 36 m / h after regeneration, indicating a significant improvement in activity and a good overall performance enhancement of the catalyst.

[0065] 2. The specific surface area of ​​the catalyst before regeneration was found to be 39.55 m². 2 / mg, increased to 42.83mg after regeneration. 2 / mg indicates that the catalyst's micropores were well cleared and the reaction area was restored.

[0066] 3. The results of the main component testing are as follows:

[0067] (2) Use XRF to detect other components in the sample, see Table 1 below for details.

[0068] Table 1

[0069] <![CDATA[TiO2]]> 78.05 84.70 <![CDATA[WO3]]> 4.44 0.18 <![CDATA[V2O5]]> 0.59 0.07 <![CDATA[SiO2]]> 7.03 2.26 High 1.74 0.34 <![CDATA[SO3]]> 4.06 0.40 <![CDATA[Al2O3]]> 1.80 0.57 MgO 0.29 0.09 <![CDATA[Na2O]]> 0.12 0.03 <![CDATA[K2O]]> 0.09 0.02

[0070] As shown in Table 1, the main components of the ash, SiO2, Al2O3, CaO, MgO, Na2O and K2O, were significantly reduced, indicating a good regeneration effect. The active components V2O5 and WO3 were also cleaned, achieving the cleaning of the catalyst blank.

[0071] Same as Example 1.

[0072] Example 3

[0073] A method for staged regeneration of a denitrification catalyst from a raw material includes the following steps:

[0074] (1) Manually remove the floating dust on the outer surface of the catalyst frame and automatically remove the dust in the catalyst unit channel with compressed air.

[0075] (2) Use a high-pressure water gun with appropriate pressure to spray deionized water for initial cleaning. After automatic rinsing, manually rinse the catalyst with a high-pressure water gun to remove ash.

[0076] (3) Surface cleaning: Immerse the catalyst completely in general reagent A. Clean the catalyst for 60 minutes by bubbling with compressed air, while simultaneously bubbling with compressed air at the bottom of the cleaning tank to soften the dirt, at a temperature of 60°C.

[0077] (4) Detailed cleaning: Immerse the catalyst cleaned with universal reagent A completely in the prepared universal reagent B, with the reagent level above the catalyst surface, and clean the catalyst for 120 minutes by bubbling with compressed air.

[0078] (5) Activation cleaning: Transfer the catalyst to an ultrasonic tank containing the prepared universal reagent C, with the reagent level above the catalyst surface, and turn on the ultrasonic waves for a thorough cleaning for 50 minutes.

[0079] (6) Transfer the catalyst to a clean water tank, with the liquid level above the catalyst surface, and rinse with clean water by bubbling to remove surface residue for 30 minutes.

[0080] (7) Push the cleaned catalyst into the drying furnace, start the drying program, and the drying heating rate shall not exceed 7°C / minute. When the furnace is fully heated to 220°C, keep it warm and dry, and then cool it down. The cooling rate shall not exceed 7°C / minute.

[0081] Universal Agent A is a weakly alkaline soaking solution, prepared from the following raw materials by weight percentage: 3% sodium hydroxide, 0.1% sodium phosphate, and the balance being deionized water.

[0082] The preparation method of universal drug A includes the following steps:

[0083] The solution is prepared by adding 3% sodium hydroxide and 0.1% sodium phosphate to deionized water at 60°C and mixing thoroughly.

[0084] Universal Agent A provides an alkaline washing solution atmosphere, which mainly removes impurities such as silicon and aluminum from the surface and interior of the catalyst, and can partially dissolve the worm-like deposits of dirt in the micropores of the catalyst.

[0085] The preparation method of universal drug B includes the following steps:

[0086] Add 0.2 wt% aminosulfonic acid, 1 wt% hydrochloric acid, 1 wt% nitric acid, 3% ammonium fluoride, and 1 wt% ethylene oxide condensate to deionized water, stir evenly at room temperature, and let stand to obtain the desired reagent.

[0087] Among them, aminosulfonic acid, hydrochloric acid, and nitric acid serve as the main acid sources of the reagent, undergoing ion exchange with ammonium fluoride to replenish and remove impurities in the micropores; ethylene oxide condensate has good dispersibility, which makes it difficult for the scale stripped from the catalyst to agglomerate, maintains its dispersibility, and is more conducive to cleaning and removal, changes the contact performance of scale on the catalyst surface, and promotes the stripping and removal of scale on the pore surface.

[0088] When using general-purpose reagent B, a temperature of 20-30℃ should be maintained to promote better performance. During cleaning, gas should be introduced for bubbling to promote contact between the reagent and the catalyst, enhance solution fluidity, and accelerate the removal of catalyst residue. The temperature should not be too high to avoid acid fumes evaporating and causing harm to humans and polluting the environment.

[0089] The preparation method of universal drug C includes the following steps:

[0090] Add 4 wt% oxalic acid, 0.2 wt% sulfuric acid, and 0.01 wt% glycolic acid to deionized water and stir until homogeneous at room temperature.

[0091] Hydroxyacetic acid has ion chelating properties and can complex with various metal impurities, effectively removing alkali (earth) metal components from catalysts.

[0092] When using universal agent C, a temperature of 30-40℃ must be maintained, and an ultrasonic oscillation process should be used as an auxiliary method, with an ultrasonic frequency of 40Hz and an ultrasonic time of 20 minutes. Because the ultrasonic process generates heat, the water temperature must be kept from rising excessively.

[0093] Same as Example 1.

[0094] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0095] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for staged regeneration of a denitrification catalyst from a raw material, characterized in that, Includes the following steps: The catalyst is pre-cleaned to remove dust from its surface and interior. Then, it is cleaned step by step with at least three different agents, followed by water washing, drying, and cooling. The method uses three different agents for step-by-step cleaning, namely, universal agent A, universal agent B, and universal agent C. The method involves a step-by-step cleaning process using three different agents, including: (1) Surface cleaning: The catalyst is completely immersed in the universal reagent A and cleaned by bubbling with compressed air at a temperature of 50-60℃. (2) Detailed cleaning: Immerse the catalyst cleaned with general agent A completely in the prepared general agent B, with the agent level above the catalyst surface, and clean the catalyst for 60-120 minutes by bubbling with compressed air. (3) Activation cleaning: Transfer the catalyst to an ultrasonic tank containing a general reagent C, with the reagent level above the catalyst surface, and turn on the ultrasonic waves to perform a thorough cleaning for 10-60 minutes. The universal reagent A is a weakly alkaline soaking solution, prepared from the following raw materials by weight percentage: sodium hydroxide 0.1-3%, sodium phosphate 0.1-2%, and the balance being deionized water; The preparation method of the universal drug A includes the following steps: At 50-60℃, add 0.1-3% sodium hydroxide and 0.1-2% sodium phosphate to deionized water, mix well to obtain the desired reagent; The preparation method of the universal drug B includes the following steps: Add 0.2-5 wt% aminosulfonic acid, 0.1-1 wt% hydrochloric acid, 0.1-1 wt% nitric acid, 0.3-3 wt% ammonium fluoride, and 0.1-1 wt% ethylene oxide condensate to deionized water, stir evenly at room temperature, and let stand to obtain the desired reagent. General-purpose agent B needs to be maintained at a temperature of 20-30℃ during use; The preparation method of the universal drug C includes the following steps: Add 0.5-4 wt% oxalic acid, 0.2-0.5 wt% sulfuric acid, and 0.01-0.1 wt% glycolic acid to deionized water, and stir until homogeneous at room temperature. When using general-purpose agent C, a temperature of 30-40℃ must be maintained.

2. The method for staged regeneration of a denitrification catalyst in a raw material according to claim 1, characterized in that, The water washing includes the following steps: Transfer the catalyst to a clean water tank, ensuring the water level is above the catalyst surface. Rinse with clean water by bubbling for 20-50 minutes to remove surface residue.

3. The method for staged regeneration of a denitrification catalyst in a raw material according to claim 1, characterized in that, The drying and cooling steps include: The cleaned catalyst is pushed into the drying furnace, and the drying program is started. The drying heating rate does not exceed 7°C / minute. When the furnace is fully heated to 200-245°C, it is kept at that temperature for drying. Then, the temperature is lowered, and the cooling rate does not exceed 7°C / minute.