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Pt/CeO2 as Catalyst for Nonoxidative Coupling of Methane: Oxidative Regeneration
Hao Zhang1, Valery Muravev1, Liang Liu1
1Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
The Journal of Physical Chemistry Letters
|July 21, 2023
Summary
Efficient catalysts for direct nonoxidative methane coupling are crucial. Isolated platinum (Pt) on ceria (CeO2) initially activates methane, but sintering leads to deactivation. Regeneration and alloy formation are key for sustained ethylene production.
Area of Science:
- Catalysis
- Materials Science
- Chemical Engineering
Background:
- Direct nonoxidative coupling offers a promising pathway for methane upgrading.
- Commercialization is limited by the need for highly efficient catalysts.
- Platinum on ceria (Pt/CeO2) with isolated Pt species is of recent interest.
Purpose of the Study:
- To investigate the catalytic role and stability of isolated Pt centers on CeO2 under nonoxidative methane coupling conditions.
- To understand the deactivation mechanisms and explore regeneration strategies for Pt/CeO2 catalysts.
- To identify the active phase responsible for methane activation during prolonged reactions.
Main Methods:
- Flame spray pyrolysis (FSP) for catalyst preparation.
- Nonoxidative methane coupling reaction at 800 °C.
- In situ regeneration using oxygen.
Main Results:
- Isolated Pt sites on CeO2 initially activate methane but sinter at 800 °C, reducing ethylene and ethane yields.
- An in situ regeneration strategy in oxygen effectively redisperses agglomerated Pt.
- Isolated Pt centers are active only in the initial stage; the CePt5 alloy becomes the active phase during prolonged reactions.
Conclusions:
- Catalyst deactivation via Pt sintering is a significant challenge for isolated Pt/CeO2 in nonoxidative methane coupling.
- In situ regeneration offers a viable method to restore catalyst activity.
- The formation of a CePt5 alloy is critical for sustained methane activation and upgrading under harsh reaction conditions.
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