Design of Pd-based pseudo-binary alloy catalysts for highly active and selective NO reduction

Area of Science:

• Materials Science
• Catalysis
• Environmental Chemistry

Background:

• Nitrogen oxides (NOx) are major air pollutants.
• Efficient catalytic reduction of NOx is crucial for environmental protection.
• Palladium-based catalysts show promise but require optimization for activity and selectivity.

Purpose of the Study:

• To develop highly active and selective palladium-based alloy catalysts for NOx reduction by CO.
• To investigate the effect of bimetallic compositions on catalytic performance.
• To elucidate the structure-activity relationships and reaction mechanisms.

Main Methods:

• Synthesis and characterization of Pd-based bimetallic catalysts (PdM/Al2O3).
• Evaluation of catalytic activity and selectivity for NO reduction by CO.
• Advanced characterization techniques including HAADF-STEM-EDS, EXAFS, and CO-FT-IR.
• Mechanistic studies using kinetic analysis, operando XAFS, and Density Functional Theory (DFT) calculations.

Main Results:

• PdIn/Al2O3 exhibited excellent N2 selectivity (100%) at 200°C.
• Optimized Pd(In0.33Cu0.67)/Al2O3 demonstrated complete NO to N2 conversion at 200°C and higher.
• The pseudo-binary alloy structure was confirmed.
• In enhanced N2O decomposition and CO oxidation, while Cu improved NO adsorption and dissociation.

Conclusions:

• The developed Pd(In0.33Cu0.67)/Al2O3 catalyst offers unprecedented performance for NOx reduction.
• The synergistic effects of In and Cu in the pseudo-binary alloy structure are key to enhanced activity and selectivity.
• This study provides fundamental insights into catalyst design for environmental catalysis.