Minslite Series Catalysts for Ozone/CO/VOCs Removal
Where does exhaust gas pollution come from and what types are there?
| Types of pollutants | Source industry sectors | Processing equipment and technology | The goals and functions of catalysts |
| carbon monoxide | Chemical industry, steel industry, automobile exhaust, oil-fired boilers | CO catalytic oxidation furnace, automotive three-way catalytic converter | Catalyze the oxidation of CO to CO₂ at low temperatures. |
| Methane/Non-methane total hydrocarbons | Natural gas extraction, biogas utilization, coal mine ventilation | Catalytic burner, RTO/RCO | Catalytic combustion of low-concentration methane enables energy recovery or compliance with emission standards. |
| Nitrogen oxides | Electricity, steel, cement, glass, chemicals, shipbuilding, diesel vehicles | SCR denitrification system, diesel engine SCR aftertreatment, catalytic decomposition | At lower temperatures, the catalytic reducing agent (NH₃/urea) reacts with NOx to produce N₂ and H₂O. |
| Sulfuric acid mist/organic sulfur | Chemical industry, lithium battery industry, petrochemical industry | Catalytic oxidation absorption | Organic sulfur (such as thiols) is catalytically oxidized to SO₂, which is then absorbed by alkaline solution. |
| Volatile organic compounds | Petrochemical, chemical, coating, printing, electronics, pharmaceutical | Catalytic combustion unit, regenerative catalytic combustion unit, catalytic oxidation unit | At temperatures far below those of direct combustion, catalytic VOCs are completely oxidized to CO₂ and H₂O. |
| dioxins | Waste incineration, steel sintering, hazardous waste incineration | Catalytic filtration system, low-temperature SCR catalytic system | Catalytic decomposition of dioxin molecules at lower temperatures. |
| ozone | Indoor air purification, aircraft cabins, specific industrial processes | Ozone catalytic decomposition device | Catalysts decompose ozone into oxygen at room temperature. |
Why is catalytic combustion and catalyst solution?
We mainly discuss the emission and treatment of waste gas pollutants from industrial activities , most of which are essentially chemical energy . The most thorough way to render them harmless is to oxidize and decompose them into CO₂ and H₂O . Currently, the mainstream treatment methods are catalytic combustion, high-temperature incineration, and physical adsorption, with catalytic combustion offering the best performance and cost-effectiveness.
Catalytic Process Principle
Catalysts are primarily used to eliminate gaseous pollutants through chemical reactions, with various catalytic reactors being the core equipment. The typical treatment process is: pretreatment (dust removal, cooling, etc.) → catalytic reactor → subsequent treatment (such as desulfurization, dehumidification) or direct emission. As the core chemical reaction unit in the treatment process , the catalyst’s key role is to “reduce the activation energy of the reaction and change the reaction pathway . “
Lower the reaction temperature: enable the reaction to proceed efficiently at temperatures far below those required for thermal reactions. For example, direct combustion of VOCs requires temperatures above 800℃, while catalytic combustion only requires 300-500℃; the reduction of NOx by NH₃ requires temperatures above 900℃ without a catalyst, but only 300-400℃ with a catalyst (SCR).
Improve reaction rate and efficiency: At the same temperature, the reaction rate is greatly accelerated, enabling pollutants to achieve extremely high removal rates (>90%, or even >99%) within a very short gas residence time.
Energy saving and consumption reduction: Due to the significant reduction in reaction temperature, fuel consumption can be significantly reduced, or economical treatment of low-concentration waste gas can be achieved.
How to select catalysts and design solutions
Catalyst selection is a complex systems engineering project that requires customized solutions based on specific operating conditions and full consideration of factors such as the pollution itself and process conditions.
1. A complete analysis of the waste gas composition is the primary prerequisite for selection , requiring a comprehensive understanding of the component type, reactivity, concentration, flow rate, and pressure of the target gas, as well as potential toxic substances .
| Consider key points | Catalyst characteristic requirements | Example description |
| 1. Selectivity | Selectivity of the target response | SCR catalysts require high selectivity to prevent the oxidation of NH₃. Some VOCs oxidation catalysts must avoid the formation of dioxins or NOx. |
| 2. Activity and Temperature Window | Activation temperature, optimal temperature, and high-temperature tolerance | VOCs catalysis: Noble metal catalysts have low activation temperatures (~200℃), while metal oxide catalysts have higher activation temperatures (~300℃). SCR catalysts have a strict temperature window (300-400℃). |
| 3. Airspeed and lifespan | Unit catalyst gas processing capacity and expected service life | High space velocities can reduce catalyst usage, but they can affect conversion efficiency. The design life is typically 2-4 years, but the actual lifespan is affected by operating conditions. |
| 4. Mechanical strength | Abrasion resistance, compressive strength | To prevent the catalyst from pulverizing and clogging under high temperature and high airflow. Honeycomb catalyst has high strength and low pressure drop. |
| 5. Anti-toxic | Resistance to “toxic substances” in flue gas | The main limiting factors are arsenic, phosphorus, alkali metals, and heavy metals, which can permanently deactivate SCR catalysts; and sulfur, halogens, silicon, and lead, which can poison VOCs/CO catalysts. A resistant formulation must be selected based on the composition of the waste gas. |
| 6. Cost | Initial installation cost, recycling/replacement cost | Precious metal catalysts have high activity but high cost; non-precious metal catalysts are low cost, but their activity/resistance may be slightly inferior. A comprehensive evaluation is required. |
2. It is necessary to clearly define the catalytic process conditions , and to build or improve the catalytic emission system based on the type, temperature, flow rate, pressure of the waste gas , and the conditions at the emission site, as well as to determine the method of catalyst use. Regarding the operation of the catalyst, we offer the following recommendations.
| Reference Guide | Factors to consider and precautions |
| Usage conditions | 1. Temperature window : It must be operated within the catalyst’s active temperature range, avoiding temperatures below the activation temperature or above the tolerance temperature. |
| 2. Cleanliness : The inlet exhaust gas must undergo sufficient pretreatment (dust removal, oil mist removal, acid mist removal) to prevent physical blockage and chemical poisoning. | |
| 3. Reactant ratio : For example, SCR requires precise control of the ammonia-nitrogen ratio , and VOCs oxidation requires ensuring sufficient oxygen content . | |
| 4. Uniform flow field : The gas flow and reactant concentration entering the reactor must be uniformly distributed; otherwise, local efficiency will be low, affecting the overall effect. | |
| Dosage and administration | 1. Filling method : Modular installation to ensure sealing and prevent airflow short circuit. |
| 2. Air speed control : The actual operating air volume should not exceed the design value significantly for an extended period. | |
| 3. Dosage : Determined by the design space velocity. For example, to treat 100,000 Nm³/h flue gas with a design space velocity of 3000 h⁻¹, the catalyst volume is approximately 33.3 m³. | |
| Limitations and restrictions | 1. Poisoning and deactivation : Maximum limitation . Sulfur, phosphorus, halogens, heavy metals, dust cover, etc., can cause irreversible or reversible decrease in catalyst activity. |
| 2. Temperature sensitivity : High-temperature sintering can cause active components to agglomerate and become permanently deactivated; long-term low-temperature operation can lead to low efficiency and ammonium salt blockage. | |
| 3. Scope of application : There are certain requirements for the concentration of pollutants. If the concentration is too low, the driving force of the reaction will be insufficient. If the concentration is too high, the temperature may be too high or the reaction may be incomplete. | |
| 4. Cost : High-performance catalysts, especially precious metal catalysts, have high initial investment and replacement costs. | |
| 5. Hazardous waste : Deactivated catalysts are usually classified as hazardous waste and must be handled by a qualified organization, incurring subsequent disposal costs. |
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