Treating PCDD/Fs by combined catalysis and activated carbon adsorption

Area of Science:

• Environmental Chemistry
• Catalysis
• Air Pollution Control

Background:

• Vanadium pentoxide-tungsten oxide/titanium dioxide (V2O5-WO3/TiO2) catalysts are effective for gas-phase dioxin destruction.
• Catalyst performance, including removal efficiency (RE) and destruction efficiency (DE), declines with increasing initial dioxin concentrations (IC).

Purpose of the Study:

• To enhance the efficiency of V2O5-WO3/TiO2 catalysts for dioxin destruction at high initial concentrations.
• To investigate the impact of incorporating activated carbons (AC) into the catalytic system.

Main Methods:

• A gas-phase dioxin-generating system was employed to supply controlled, stable initial concentrations (IC) of dioxins.
• V2O5-WO3/TiO2 catalysts were tested alone and in mixtures with two types of activated carbon (AC-1 from lignite, AC-2 from coconut shell).
• Experiments were conducted at various temperatures (160-200°C) to evaluate removal and destruction efficiencies.

Main Results:

• At the highest IC (20.5 ng I-TEQ Nm(-3)) and 200°C, the catalyst alone achieved only 76% RE and 64% DE for PCDD/Fs.
• Mixing the catalyst with AC-2 significantly improved performance, reaching 90.1% RE and 82.0% DE under the same conditions.
• The catalyst/AC mixture demonstrated superior performance at lower temperatures (160°C and 180°C).
• The specific characteristics of the activated carbon influenced the adsorption and degradation capabilities of the combined system.

Conclusions:

• Activated carbons enhance the performance of V2O5-WO3/TiO2 catalysts in destroying dioxins, particularly under high initial concentration conditions.
• The catalytic mixture offers improved efficiency and better performance at lower operating temperatures compared to the catalyst alone.
• The type of activated carbon used plays a crucial role in the overall effectiveness of the dioxin destruction system.