5D operando tomographic diffraction imaging of a catalyst bed.

Area of Science:

• Materials Science
• Chemical Engineering
• Catalysis Science

Background:

• Methane reforming catalysts are crucial for energy production.
• Understanding catalyst deactivation mechanisms is essential for improving efficiency.
• Complex multi-component catalysts present challenges in characterization.

Purpose of the Study:

• To investigate the chemical evolution of a Ni-Pd/CeO2-ZrO2/Al2O3 catalyst during methane reforming.
• To correlate catalyst particle changes with the local gas environment.
• To elucidate the roles of promoters and understand catalyst deactivation pathways.

Main Methods:

• First 5D tomographic diffraction imaging experiment.
• Analysis of over 2x10^6 diffraction patterns using Rietveld refinement.
• Mapping of catalyst heterogeneities across multiple scales (Å to μm).

Main Results:

• Detailed 3D maps of unit cell lattice parameters, crystallite sizes, and phase distributions.
• Tracking of Ni-containing species evolution.
• Identification of heterogeneities in catalyst structure and composition.

Conclusions:

• The 5D approach provides unprecedented insight into catalyst behavior under reaction conditions.
• The study elucidates the roles of CeO2-ZrO2 promoters in methane reforming.
• Understanding these dynamics is key to mitigating partial oxidation catalyst deactivation.