Microenvironment engineering for enhancing catalytic active sites for the CO oxidation reaction

Area of Science:

• Catalysis
• Materials Science
• Environmental Engineering

Background:

• Carbon monoxide (CO) removal from industrial sintering flue gases is a critical challenge in gas purification.
• Efficient catalytic systems are essential for effective low-temperature CO oxidation.

Purpose of the Study:

• To investigate the efficacy of copper-based catalysts utilizing TiO₂ synthesized under supercritical conditions for low-temperature CO oxidation.
• To explore the role of copper valence states (Cu⁺) and catalyst morphology in enhancing catalytic activity.

Main Methods:

• Synthesis of TiO₂ under supercritical conditions.
• Preparation and characterization of Cu/sc-TiO₂ and Cu/TiO₂ catalysts using XPS, EPR, and CO-DRIFT.
• Evaluation of catalytic activity for CO oxidation at low temperatures.
• Analysis of thermal treatment effects on catalyst properties using DRIFT and TPSR.

Main Results:

• Cu/sc-TiO₂ catalysts demonstrated complete CO conversion at 120 °C, significantly outperforming conventional TiO₂ catalysts.
• Higher Cu⁺ concentration (78% in Cu/sc-TiO₂ vs. 71% in Cu/TiO₂) was observed, attributed to smaller particle size and better dispersion of sc-TiO₂.
• Thermal treatment further increased the Cu⁺ ratio to 89% in Cu/sc-TiO₂-A, enhancing catalytic performance.
• In-situ DRIFT and TPSR analyses revealed that CO generation during heat treatment created a beneficial micro-reduction environment.

Conclusions:

• Supercritical fluid synthesis of TiO₂ is a viable method for enhancing copper catalyst performance in low-temperature CO oxidation.
• Optimizing copper valence states (Cu⁺) through catalyst design and thermal treatment is key to improving catalytic activity for industrial gas purification.
• Continuous hydrothermal flow synthesis offers a promising route for tailoring catalyst properties for demanding industrial applications.