Formation and Segregation of the Ru- and Rh-MgO Solid Solutions
Kazu Okumura1, Takumi Sasaki1, Sou Sugihara1
1Department of Applied Chemistry, School of Advanced Engineering, Kogakuin University, 2665-1 Nakano-machi Hachioji-city, 192-0015 Tokyo, Japan.
ACS Omega
|November 25, 2024
Summary
Thermal treatment of ruthenium (Ru) and rhodium (Rh) on magnesium oxide (MgO) formed solid solutions. Higher temperatures (1273 K) increased metal dispersion, enhancing catalytic activity for ammonia decomposition.
Area of Science:
- Materials Science
- Catalysis
- Nanotechnology
Background:
- Magnesium oxide (MgO) is a common support for metal catalysts.
- Understanding structural changes of supported metals under thermal stress is crucial for catalyst design.
Purpose of the Study:
- Investigate structural modifications of Ru and Rh nanoparticles on MgO after thermal treatment.
- Correlate structural changes with catalytic performance, specifically NH3 decomposition.
Main Methods:
- X-ray absorption spectroscopy (XAS), including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS).
- CO adsorption to measure metal dispersion.
- Catalytic activity testing for ammonia (NH3) decomposition.
Main Results:
- Formation of Ru-MgO and Rh-MgO solid solutions upon thermal treatment.
- Optimal solid solution formation occurred at 873 K (Ru-MgO) and 1073 K (Rh-MgO).
- Increased metal dispersion at 1273 K due to segregation from solid solutions, correlating with higher NH3 decomposition activity for Ru/MgO.
Conclusions:
- Thermal treatment induces solid solution formation and subsequent segregation of Ru and Rh on MgO.
- Higher temperatures (1273 K) promote metal dispersion, enhancing catalytic activity.
- The study provides insights into structure-activity relationships for supported metal catalysts.
