A regeneration method of a non-noble metal VOCs catalyst

Abstract

This invention provides a method for regenerating non-precious metal VOCs catalysts, comprising the following steps: S1, purging the non-precious metal VOCs catalyst with high-pressure pulse purging until there are no obvious impurities in the catalyst honeycomb channels; S2, ultrasonically cleaning the purged non-precious metal VOCs catalyst in a weak acid solution, draining the cleaned catalyst, rinsing it with clean water, and then drying it; S3, reducing the dried non-precious metal VOCs catalyst in an atmosphere furnace, immersing the reduced non-precious metal VOCs catalyst in a solution of catalytically active components for ultrasonic treatment; then draining and rapidly drying; S4, activating the dried non-precious metal VOCs catalyst in a high-temperature furnace to obtain a regenerated non-precious metal VOCs catalyst.

Description

Technical Field

[0001] This invention relates to the field of waste recycling technology, specifically to a method for the regeneration and preparation of a non-precious metal VOCs catalyst. Background Technology

[0002] Volatile organic compounds (VOCs), as one of the main sources of air pollution, are widely generated in industrial fields such as chemical, printing, and coating. They not only cause serious damage to the ecological environment but also directly threaten human health. Catalytic combustion technology has become one of the mainstream technologies for VOCs treatment due to its advantages such as high purification efficiency, low energy consumption, and no secondary pollution. As the core of this technology, the performance and cost of the catalyst directly determine the potential for industrial application.

[0003] In the development of VOCs catalytic combustion technology, traditional noble metal catalysts (such as Pt, Pd, and Rh-based catalysts) have long held a dominant position due to their excellent low-temperature catalytic activity and stability. However, the scarcity and high cost of noble metal resources, coupled with their susceptibility to poisoning by impurities such as Cl and S, have significantly limited their widespread adoption in large-scale industrial applications. Against this backdrop, non-noble metal VOC catalysts (such as transition metal oxides, perovskite oxides, and spinel oxides) have gradually become a research hotspot due to their significant advantages. From a cost perspective, non-precious metals (such as Mn, Co, Ni, Cu, etc.) are abundant in the Earth's crust, making raw material acquisition easy and their preparation cost only a fraction of that of precious metal catalysts, significantly lowering the application threshold for catalytic combustion technology. In terms of performance adaptability, some non-precious metal catalysts, through component regulation and structural design, can achieve highly efficient degradation of different types of VOCs (such as benzene compounds, aldehydes, ketones, and esters), and exhibit catalytic activity comparable to precious metal catalysts in the medium-to-high temperature range (250-400℃). Regarding impurity resistance potential, some non-precious metal oxides (such as MnO...)... x CeO2-based composite materials have strong redox capabilities and are more tolerant to low concentrations of impurities such as Cl and S than traditional precious metal catalysts, making them a potential solution for treating complex industrial exhaust gases.

[0004] Despite the significant advantages of non-precious metal VOC catalysts, poisoning and deactivation during long-term industrial operation have become key bottlenecks restricting their service life and industrial application. On the one hand, industrial exhaust gases often contain trace amounts of elements such as Cl, S, and P, which can strongly interact with the active sites of the catalyst. For example, Cl... -It can form stable metal chlorides with transition metal active centers, covering active sites and destroying the catalyst crystal structure; sulfur can be converted into SO2 or SO3, combining with hydroxyl groups on the catalyst surface to form sulfates, leading to permanent deactivation of active sites. On the other hand, carbon deposits may be generated during the catalytic combustion of VOCs: when the reaction temperature is low (below 200℃), VOC molecules are difficult to completely oxidize after adsorption on the catalyst surface, easily forming stubborn carbon deposits; while when the reaction temperature is too high (above 450℃), some VOCs will undergo cracking reactions, and the generated carbon species will quickly deposit on the catalyst surface, blocking pores and isolating active sites from contact with reactants, ultimately leading to a sharp decline in catalyst activity. Statistical data shows that the service life of non-precious metal VOC catalysts in industrial scenarios is usually only 6-12 months, far shorter than that of precious metal catalysts (2-3 years). Frequent catalyst replacement not only increases the operating costs of enterprises but also generates a large amount of solid waste, which is inconsistent with the concept of green and low-carbon development.

[0005] To address the deactivation problem of non-precious metal VOC catalysts, regeneration has become a core technical approach to extend their service life and reduce application costs. However, the regeneration process of non-precious metal catalysts faces numerous technical challenges, hindering the industrial application of regeneration technology. Firstly, balancing the selectivity of regeneration methods is difficult: current mainstream regeneration methods include thermal regeneration (high-temperature ablation to remove carbon deposits), chemical regeneration (acid and alkali solution washing to remove poisoned species), and plasma regeneration (high-energy particle degradation of carbon deposits and poisoned species). While thermal regeneration is simple to operate, the thermal stability of non-precious metal catalysts is generally low. For example, MnO... x -CoO x Composite catalysts are prone to grain sintering above 500℃, leading to a significant decrease in specific surface area. In chemical regeneration, while strong acid solutions can effectively remove sulfate-poisoned species, they corrode the catalyst support (such as Al2O3 and TiO2), damaging its pore structure and dispersion performance. While plasma regeneration can achieve carbon deposition degradation at low temperatures, its removal efficiency for strongly adsorbed poisoned species such as Cl and P is insufficient, and high-energy particles may damage the electronic structure of the catalyst's active sites. Secondly, the uniformity of the regeneration process is difficult to control: industrial non-precious metal catalysts are mostly honeycomb or granular, with complex internal pore structures, making it difficult for regeneration reagents (such as high-temperature gases, acid and alkali solutions) to penetrate the catalyst interior, resulting in significant differences in the degree of regeneration between the surface and the interior. Over-regeneration of the surface may lead to the loss of active sites, while incomplete internal regeneration leaves behind a large number of deactivated species. After regeneration, the catalyst activity can only recover to 60%-70% of that of a fresh catalyst, failing to meet industrial requirements. Finally, the stability of the regeneration effect is difficult to guarantee: after multiple regenerations, the active sites of non-precious metal catalysts will continue to be lost, and new impurity ions may be introduced during the regeneration process (such as Na+ in chemical regeneration). +K + This leads to a gradual decline in the catalyst's regeneration performance. Typically, after 2-3 regenerations, the catalyst activity recovery rate drops below 50%, rendering it worthless for regeneration.

[0006] In summary, non-precious metal VOC catalysts have broad application prospects in the field of VOCs treatment due to their advantages such as low cost and abundant resources. However, the deactivation problem and regeneration difficulties during long-term operation have become key obstacles restricting their industrial-scale promotion. Therefore, in-depth research on the deactivation mechanism of non-precious metal VOC catalysts and the development of efficient, stable, and low-cost regeneration technologies are of significant theoretical and practical value for promoting the green and large-scale application of VOCs catalytic combustion technology. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for regenerating and preparing non-precious metal VOCs catalysts that can remove contaminants attached to the catalyst surface and regulate the deactivated or poisoned catalytic components on the surface to restore their catalytic performance.

[0008] The technical solution adopted by this invention to solve its technical problem is: A method for regenerating a non-precious metal VOCs catalyst includes the following steps: S1, purging the non-precious metal VOCs catalyst with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, ultrasonically cleaning the purged non-precious metal VOCs catalyst in a weak acid solution, draining the cleaned catalyst, rinsing it with clean water, and then drying it; S3, reducing the dried non-precious metal VOCs catalyst in an atmosphere furnace, immersing the reduced non-precious metal VOCs catalyst in a solution of catalytically active components for ultrasonic treatment, then draining and rapidly drying it; S4, activating the dried non-precious metal VOCs catalyst in a high-temperature furnace to obtain a regenerated non-precious metal VOCs catalyst.

[0009] Furthermore, the weak acid solution is a 10-20% weak acid solution, and the weak acid solution includes citric acid and acetic acid.

[0010] Furthermore, the ultrasonic cleaning time in S2 is 30-120 min.

[0011] Furthermore, in S3, the atmosphere inside the atmosphere furnace is a reducing atmosphere, which is nitrogen mixed with hydrogen or carbon monoxide.

[0012] Furthermore, the atmosphere furnace treatment temperature is 200-400℃, and the atmosphere furnace treatment time is 1-3h.

[0013] Furthermore, the catalytically active component solution includes manganese, copper, cerium, zinc, transition metal nitrates, chlorides, and organic salts.

[0014] Furthermore, the rapid drying method includes microwave drying and flash drying.

[0015] Furthermore, the activation temperature in the high-temperature furnace is 300-450℃, and the activation time in the high-temperature furnace is 1-4 hours.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes high-pressure pulse purging to maximally remove fine particulate contaminants such as dust adhering to or clogging the pores of the catalyst honeycomb structure. After removing surface impurities, the catalyst is immersed in a weak acid solution and subjected to ultrasonic treatment, effectively removing metal components and other easily soluble salts adhering to the catalyst surface. Simultaneously, the use of weak acid treatment minimizes the loss of active catalyst components due to acid dissolution. Following weak acid treatment, the catalyst is rinsed with clean water to prevent residual organic weak acid from affecting subsequent reduction and regeneration, and to prevent organic components from transforming into surface carbon in an oxygen-deficient environment, thus affecting catalytic performance regeneration. The atmosphere furnace reduction and regeneration process reduces the active components on the catalyst surface that have become over-oxidized and deactivated due to long-term catalysis. The reduced catalyst is then immersed in an active component solution to further load the active components, compensating for the active components lost during catalyst use. Rapid drying avoids the localized enrichment of active components caused by moisture migration during slow drying, preventing uneven distribution of catalytic active components. High-temperature calcination activation transforms the reduced and reloaded active components into catalytically active transition metal mineral phases, thereby restoring the catalyst's catalytic performance. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Example 1 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, after purging, the non-precious metal VOCs catalyst is placed in a 15% citric acid solution for ultrasonic cleaning for 60 min; after cleaning, it is drained, rinsed with water and then dried. S3. The dried non-precious metal VOCs catalyst is placed in an atmosphere furnace for reduction treatment, using 15% hydrogen and 85% nitrogen as the reducing gas. After reduction treatment, the non-precious metal VOCs catalyst is immersed in a manganese-copper solution and ultrasonically treated for 30 minutes. Then it is drained and rapidly dried using microwave drying. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 450°C for 2 hours to obtain a regenerated catalyst. Comparative experiments showed that the catalyst's catalytic efficiency for toluene increased from 47% to 89%.

[0019] Example 2 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, after purging, the non-precious metal VOCs catalyst is placed in an 18% acetic acid solution for ultrasonic cleaning for 60 min; after cleaning, it is drained, rinsed with water and then dried. S3. The dried non-precious metal VOCs catalyst is placed in an atmosphere furnace for reduction treatment, using 10% carbon monoxide and 90% nitrogen as the reducing gas. After reduction treatment, the non-precious metal VOCs catalyst is impregnated in a manganese-copper solution and ultrasonically treated for 20 minutes. Then it is drained and rapidly dried using microwave drying. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 400℃ for 2 hours to obtain the regenerated catalyst. Comparative experiments showed that the catalyst's catalytic efficiency for toluene increased from 64% to 92%.

[0020] Example 3 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, the purged non-precious metal VOCs catalyst was placed in a 15% acetic acid and citric acid solution (acetic acid:citric acid = 2:1) for ultrasonic cleaning for 50 min; after cleaning, it was drained, rinsed with water and dried. S3. The dried non-precious metal VOCs catalyst is placed in an atmosphere furnace for reduction treatment, using 10% hydrogen and 90% nitrogen as the reducing gas. After reduction treatment, the non-precious metal VOCs catalyst is immersed in a manganese-copper solution and ultrasonically treated for 20 minutes. Then it is drained and rapidly dried using microwave drying. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 380℃ for 2 hours to obtain a regenerated catalyst. Comparative experiments showed that the catalyst's catalytic efficiency for toluene increased from 59% to 93%.

[0021] Comparative Example 1 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, after purging, the non-precious metal VOCs catalyst is placed in a 15% citric acid solution for ultrasonic cleaning for 60 min; after cleaning, it is drained, rinsed with water and then dried. S3, the dried non-precious metal VOCs catalyst was placed in an atmosphere furnace for heat treatment without controlling the reducing atmosphere; after reduction treatment, the non-precious metal VOCs catalyst was impregnated in a manganese-copper solution and ultrasonically treated for 30 minutes; after the impregnated non-precious metal VOCs catalyst was drained, it was rapidly dried using microwave drying. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 450°C for 2 hours to obtain a regenerated catalyst. Comparative experiments showed that the catalyst's catalytic efficiency for toluene increased from 47% to 78%.

[0022] Comparative Example 2 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, after purging, the non-precious metal VOCs catalyst is placed in clean water for ultrasonic cleaning for 60 min; after cleaning, it is drained, rinsed with clean water, and then dried. S3. The dried non-precious metal VOCs catalyst is placed in an atmosphere furnace for reduction treatment, using 5% hydrogen and 85% nitrogen as the reducing gas. After reduction treatment, the non-precious metal VOCs catalyst is immersed in a manganese-copper solution and ultrasonically treated for 30 minutes. Then it is drained and rapidly dried using microwave drying. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 450°C for 2 hours to obtain the regenerated catalyst. Comparative experiments showed that the catalyst's catalytic efficiency for toluene increased from 47% to 73%.

[0023] Comparative Example 3 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, after purging, the non-precious metal VOCs catalyst is placed in an 18% acetic acid solution for ultrasonic cleaning for 60 min; after cleaning, it is drained, rinsed with water and then dried. S3, the dried non-precious metal VOCs catalyst was placed in an atmosphere furnace for reduction treatment, using 10% carbon monoxide and 90% nitrogen as the reducing gas; after reduction treatment, the non-precious metal VOCs catalyst was not loaded with active components. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 400℃ for 2 hours to obtain a regenerated catalyst. Comparative experiments showed that the catalyst's catalytic efficiency for toluene increased from 64% to 75%.

[0024] Comparative Example 4 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, the purged non-precious metal VOCs catalyst was placed in an 18% nitric acid solution for ultrasonic cleaning for 60 min; after cleaning, it was drained, rinsed with water and then dried. S3, the dried non-precious metal VOCs catalyst is placed in an atmosphere furnace for reduction treatment, using 10% carbon monoxide and 90% nitrogen as the reducing gas; after reduction treatment, the non-precious metal VOCs catalyst is impregnated in a manganese-copper solution and ultrasonically treated for 30 minutes. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 400℃ for 2 hours to obtain a regenerated catalyst. Comparative tests showed that the catalyst's catalytic efficiency for toluene decreased from 64% to 46%.

[0025] Comparative Example 5 A method for regenerating and preparing a non-precious metal VOCs catalyst includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, after purging, the non-precious metal VOCs catalyst is placed in an 18% acetic acid solution for ultrasonic cleaning for 60 min; after cleaning, it is drained, rinsed with water and then dried. S3, the dried non-precious metal VOCs catalyst was placed in an atmosphere furnace for reduction treatment, using 10% carbon monoxide and 90% nitrogen as the reducing gas; after reduction treatment, the non-precious metal VOCs catalyst was not loaded with active components. S4. The dried non-precious metal VOCs catalyst was activated in a high-temperature furnace at 600℃ for 2 hours to obtain a regenerated catalyst. Comparative experiments showed that the catalyst's catalytic efficiency for toluene increased from 61% to 79%.

[0026] Analysis of the effects of Examples 1-3 and Comparative Examples 1-5 The main control conditions for each embodiment and comparative example are shown in the table below: In Examples 1-3, the control conditions were all within the scope of the claims of this patent, and the catalytic performance of the spent catalyst was improved to about 90% after treatment. In Comparative Example 1, no reducing atmosphere control was applied during the pyrolysis process. The over-oxidized or poisoned active metal components in the spent catalyst failed to be reduced to the desired valence state, resulting in a final performance of only 78%. In Comparative Example 2, rinsing with water only removed some of the deposited salts, impurities, and compounds on the surface of the spent catalyst. These impurities remained on the catalyst surface during subsequent regeneration, affecting the catalyst regeneration effect. In Comparative Example 3, the catalyst did not undergo secondary loading of active components; all catalytic performance was limited to the partial regeneration of the original active components of the spent catalyst, resulting in insufficient overall catalytic performance. In Comparative Example 5, acid washing with strong nitric acid not only removed various impurities from the surface of the spent catalyst but also caused a large-scale loss of the originally loaded metal active components. Although secondary loading occurred subsequently, the overall performance inevitably declined. In Comparative Example 5, the high-temperature activation temperature reached 600℃, causing excessive oxidation of some active components, resulting in substandard final catalytic performance.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the technical solutions of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for regenerating and preparing a non-precious metal VOCs catalyst, characterized in that: Includes the following steps: S1, the non-precious metal VOCs catalyst is purged with a high-pressure pulse until there are no obvious impurities in the catalyst honeycomb channels; S2, after purging, the non-precious metal VOCs catalyst is placed in a weak acid solution for ultrasonic cleaning. After cleaning and draining, it is rinsed with water and then dried. S3, the dried non-precious metal VOCs catalyst is placed in an atmosphere furnace for reduction treatment, and the reduced non-precious metal VOCs catalyst is impregnated in a catalytic active component solution for ultrasonic treatment. Then drain and quickly dry. S4. The dried non-precious metal VOC catalyst is placed in a high-temperature furnace for activation treatment to obtain a regenerated non-precious metal VOC catalyst.

2. The method for regenerating and preparing the non-precious metal VOCs catalyst according to claim 1, characterized in that: The weak acid solution is a 10-20% weak acid solution, which includes citric acid and acetic acid.

3. The method for regenerating and preparing the non-precious metal VOCs catalyst according to claim 1, characterized in that: The ultrasonic cleaning time in S2 is 30-120 min.

4. The method for regenerating and preparing the non-precious metal VOCs catalyst according to claim 1, characterized in that: In S3, the atmosphere inside the atmosphere furnace is a reducing atmosphere, which is nitrogen mixed with hydrogen or carbon monoxide.

5. The method for regenerating and preparing the non-precious metal VOCs catalyst according to claim 4, characterized in that: The atmosphere furnace treatment temperature is 200-400℃, and the atmosphere furnace treatment time is 1-3h.

6. The method for regenerating and preparing the non-precious metal VOCs catalyst according to claim 1, characterized in that: The catalytically active component solution includes manganese, copper, cerium, zinc, transition metal nitrates, chlorides, and organic salts.

7. The method for regenerating and preparing the non-precious metal VOCs catalyst according to claim 1, characterized in that: The rapid drying methods include microwave drying and flash drying.

8. The method for regenerating and preparing the non-precious metal VOCs catalyst according to claim 1, characterized in that: The activation temperature in the high-temperature furnace is 300-450℃, and the activation time in the high-temperature furnace is 1-4 hours.

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