What Methods Are Available to Reactivate Deactivated Catalysts?

Overview of Mainstream Deactivated Catalyst Reactivation Methods

The core logic of different reactivation methods is to "specifically eliminate the causes of deactivation," adapting to different types of deactivated catalysts:

High-temperature calcination regeneration: The core principle is to remove carbon deposits and organic sediments on the catalyst surface and in the pores through high-temperature oxidation reactions, restoring active centers and pore channels. This method is suitable for carbon-fouling deactivation (such as catalysts used in denitrification, hydrogenation, and ozone catalysis).

Solvent washing regeneration: This method utilizes the dissolution and extraction effects of acid-base solutions or organic solvents to remove soluble poisons (such as alkali metals and sulfur and chlorine impurities) from the catalyst surface. It is suitable for poisoned catalysts and often requires subsequent steps to replenish active components.

Gas reduction regeneration: This method involves using inert gas purging to remove surface impurities, and then using reducing gases such as hydrogen and carbon monoxide to redisperse sintered or oxidized active metal components and repair active centers. This method is suitable for catalysts with slight sintering and metal contamination deactivation (such as platinum-based and zeolite catalysts). Plasma Regeneration Method: Utilizing the highly active particles of plasma, this method rapidly decomposes carbon deposits and toxins. It offers advantages such as low temperature, high efficiency, and minimal damage to the catalyst matrix, but requires high equipment investment and is currently mainly used in the field of precision chemical engineering.

High-Temperature Calcination Regeneration Method: Principles, Operation, and Practical Application Cases

1. Core Principles and Operating Points

The essence of the high-temperature calcination regeneration method is "oxidative impurity removal": under an air or oxygen atmosphere, the deactivated catalyst is heated to a specific temperature (usually 300-860℃, adjusted according to the catalyst type) to allow surface carbon deposits and organic pollutants to react with oxygen, generating CO₂ and H₂O, without damaging the catalyst's support structure and active components. Operation must follow the principle of "gradient heating and precise temperature control" to avoid sudden high-temperature increases that could lead to catalyst sintering or loss of active components. The core steps include: pretreatment (removing dust, crushing to appropriate particle size) → gradient heating calcination (gradually increasing the temperature to the target temperature, maintaining it for 2-6 hours) → natural cooling (to avoid secondary oxidation).

2. Industrial Practical Application Case: SCR Denitration Catalyst Regeneration in Coal-Fired Power Plants

Denitration catalysts are core materials for controlling NOₓ emissions in coal-fired power plants. After long-term operation, they are prone to deactivation due to blockage by calcium sulfate particles in the flue gas and carbon deposition, making direct replacement extremely costly. The SCR denitration catalyst of a large coal-fired power plant unit, after 6 years of operation, showed a denitration efficiency of less than 65% and an activity level of 0.57, far exceeding the industry standard threshold.  Furthermore, the air preheater differential pressure increased, and the ammonia injection rate surged by 99.62 Nm³/h, seriously affecting the stable operation of the unit. To address this problem, a combined regeneration process of "cleaning + high-temperature calcination" was adopted. The specific implementation process and results are as follows:

(1) Pre-treatment and cleaning: First, a pressure jet machine was used to rinse and remove surface dust and pore blockages from the catalyst. Then, the catalyst was soaked in deionized water and a neutral chemical agent, combined with ultrasonic cleaning, to remove alkali metal ions and calcium sulfate deposits, creating favorable conditions for the calcination process;

(2) High-temperature calcination parameters: The cleaned catalyst was sent to a dedicated calcination furnace, using a "gradient heating" strategy, gradually increasing the temperature from room temperature to 550℃, and maintaining this temperature for 4 hours to ensure complete oxidation of carbon deposits while avoiding sintering of the catalyst support;

(3) Regeneration effect:  Testing showed that the regenerated catalyst's activity recovered to the level of fresh catalyst, the denitrification efficiency increased to over 90%, and the ammonia slip rate was controlled below 3 ppm, fully meeting the unit's environmental protection requirements;

(4) Economic benefits: This regeneration process treated a total of 626 cubic meters of catalyst, completed in 40 days. Compared to adding a new layer of catalyst (purchase cost of 32,000 RMB/cubic meter), it directly saved 10.02 million RMB in procurement costs, and reduced fan energy consumption by 2.13 million RMB, resulting in a total saving of 4.01 million RMB. The service life of the regenerated catalyst was extended to 24,000 hours, achieving both environmental compliance and cost savings.

3. Supplementary Case: Regeneration of Ozone Catalyst for Chemical Wastewater Treatment

An ozone catalyst used by a chemical company for treating biochemical effluent from wastewater treatment experienced a decline in activity after 5 years of continuous operation due to the adsorption of a large amount of organic pollutants on its surface, resulting in a TOC removal rate of less than 20%. The research team treated it using a high-temperature calcination regeneration method, and optimized the parameters through single-factor experiments, obtaining the best parameters: calcination temperature of 500℃ and holding time of 4 hours. The specific surface area of the regenerated catalyst significantly increased, and the pore channels were restored to unobstructed flow.  The TOC removal rate of the biochemical effluent from chemical wastewater treatment increased to 44.30%, reaching 77.46% of the removal efficiency of the fresh catalyst.  Furthermore, the regeneration process did not require complex chemicals, and the treatment cost was only 1/3 of the cost of purchasing new catalysts, providing a feasible solution for the recycling of ozone catalysts in the chemical industry.

Selection of Regeneration Method

When selecting a catalyst regeneration method, it is necessary to first determine the core cause of deactivation (coking, poisoning, sintering, etc.) through testing: for coking-type deactivation, high-temperature calcination regeneration is preferred due to its lowest cost and simplest operation; solvent washing regeneration can be used for poisoning-type deactivation; and gas reduction regeneration is suitable for slight sintering-type deactivation. The advantage of high-temperature calcination regeneration lies in its adaptability to most types of industrial catalysts and its stable regeneration effect. As seen in cases from coal-fired power plants and chemical wastewater treatment, it not only restores catalyst activity but also brings significant economic benefits to enterprises, making it a core technological path for promoting the recycling of industrial catalysts.

author: Hazel
date: 2025-12-22