Advanced elemental characterization during Pt-In catalyst formation by wavelet transformed X-ray absorption...

Area of Science:

• Materials Science
• Catalysis Science
• Spectroscopy

Background:

• Conventional X-ray absorption spectroscopy (XAS) methods like XANES and FT-EXAFS provide limited insight into complex catalytic mechanisms.
• Understanding the precise formation pathways of bimetallic catalysts is crucial for optimizing their performance.

Purpose of the Study:

• To demonstrate the utility of wavelet transformed X-ray absorption spectroscopy (WT XAS) in elucidating the physicochemical mechanisms of Pt-In catalyst formation.
• To compare the structural evolution of a Pt precursor on a Mg(In)(Al)Ox support under various treatment conditions using WT XAS.

Main Methods:

• Systematic application of wavelet transformed XAS (WT XAS) complemented by XANES and FT-EXAFS.
• Analysis of a Pt(acac)2 impregnated Mg(In)(Al)Ox support before and after calcination (650 °C) and subsequent H2 reduction (650 °C).
• Utilizing the simultaneous k- and R-space resolution of WT XAS for elemental discrimination and structural modeling.

Main Results:

• WT XAS effectively allocated elemental contributions to specific R-space peaks, aiding structural model development.
• Calcination decomposed acac ligands, forming atomically dispersed Pt(4+) cations on the support.
• H2 reduction resulted in the formation of 1.5 nm Pt-In alloyed nanoparticles.

Conclusions:

• WT XAS offers superior resolution for dissecting catalytic formation mechanisms compared to conventional XAS techniques.
• The study successfully mapped the transformation from a Pt precursor to Pt-In alloyed nanoparticles.
• Systematic WT XAS application holds significant potential for advancing research in catalysis and chemistry.