Influence of Particle Size Distribution on Lifetime and Thermal Stability of Ostwald Ripening of Supported Particles

• Published in: ChemCatChem Vol. 10; no. 13; pp. 2900 - 2907
• Main Authors: Hu, Sulei, Li, Wei‐Xue
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 09.07.2018
• Subjects: aggregation; Airborne particulates; Catalysis; computational chemistry; crystal engineering; kinetics; Ostwald ripening; Particle size; Particle size distribution; Reaction kinetics; supported particles; Thermal stability
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201800331

Stability of dispersed particles on their supports is one of the central topics in heterogeneous catalysis and quantifying the influence of the particle size distribution on lifetime and thermal stability is highly valuable for rational design of efficient nanocatalysts. We report here a theoretical study of Ostwald ripening of supported particles, in particular, the kinetic evolution of particle number, average size, and dispersion with respect to time and thermal temperature in a wide range of size and monodispersity. Phase diagrams of half‐lifetime and onset temperature of ripening as functions of size and monodispersity were constructed. If decreasing the average particle size, though there is a modest gain in the dispersion, the stability declines dramatically; specifically, the half‐lifetime of ripening decreases exponentially and the corresponding onset temperature decreases by hundreds of Kelvin. Decline in stability owing to the decrease in size could, however, be systematically compensated by increasing the monodispersity of the size distribution. We find that the supported particles with the same half‐life time and onset temperature could originate from different particle size distributions, whereas the particle size distribution with the same apparent dispersion could have very different onset temperature and half‐lifetime. The result highlights the importance of both size and monodispersity in particle size distribution to the ripening resistance of supported particles, and the methodology developed for simulating ripening kinetics could be used to accelerate the aging protocols. Monodispersity! With size decreasing of supported particles, though there is a modest increase in dispersion, the corresponding lifetime of ripening decreases exponentially and thermal resistance by hundreds of Kelvin. Surprisingly, the decline in stability can be compensated systematically by gradual increase of the monodispersity.