University of Science and Technology of China: Researchers Quantify Critical Particle Distance
Supported metal nanoparticles are of great importance in many industrial catalytic processes. Under high temperature, metal nanoparticle catalysts have a strong sintering tendency because of the sharply increased surface energy with the decreased particle size, leading to catalyst deactivation.
The mechanism of catalyst sintering includes particle migration and aggregation (PMC) and Ostwald ripening (OR). The nanoparticles or atom species establish contact with each other across particle distance when sintering occurs. Thus, particle spacing plays a key role in catalyst sintering. However, it has not attracted enough attention.
In a study published in Nature Communications, Prof. LIANG Haiwei and Prof. LI Weixue from the University of Science and Technology of China quantified the critical particle distance of catalyst sintering and proposed the mechanism behind the sintering phenomenon.
The researchers synthesized platinum supported on four different kinds of carbon materials with diverse specific surface areas. By adjusting the metal loading, they constructed catalyst systems with different particle spacing and investigated their sintering at 900°C. They found that there are significant critical loading and the critical particle distance that inhibit metal sintering, and then quantified the critical particle distance to inhibit the catalyst sintering.
To understand the mechanism behind the influence of particle distance on sintering of Pt/C catalysts, the researchers tracked individual nanoparticles during the heating process. They found that when average particle distance is relatively short, sintering is dominated by PMC, and when average particle distance is relatively long, it is dominated by OR.
Furthermore, the researchers investigated the sintering resistance of this type of catalyst in high temperature propane dehydrogenation catalytic reaction.
This work provided a method to predict the maximum load of a given metal nanoparticles on supports and an effective strategy to increase the maximum loading of the catalyst by adjusting the metal-support interaction and the specific surface area of the support.