Abstract
In this study, we develop a gas-phase two-stage synthetic reaction system to fabricate nanoparticles for the applications in catalysis. Material properties, including particle size, crystallinity, elemental composition, and oxidation state, were characterized complementarily by a combination of physical, spectroscopic and microscopic approach. Our results shows that the material properties of hybrid nanoparticles were tunable by choosing the suitable chemical compositions of precursors, calcination temperatures, and the reducing gases during the gas-phase synthetic process. We have refined the existing fixed-bed activity test system by incorporating non-destructive infrared spectrometers for CH4 and CO2, which can be used to analyze the catalyst activity and stability of the metal/metal oxide catalysts. The synthesized hybrid nanoparticles especially Cu-Ce-O NPs exhibited high activity, selectivity, high durability and operation stability, and ultra-low light-off temperatures in the catalysis. The Cu-Ce-O interfacial metal-support interaction promotes the redox cycle of surface oxidation of adsorbed methane and reduces coke formation, and we can depict the mechanisms catalyzed by CuCeOx-NP and CuO-NP. We fabricate CuCeOx-NP and NiCeOx-NP hybrid nanoparticles with the controllable material properties by gas-phase two-stage synthetic reaction system for the applications in methane combustion and carbon dioxide reforming reaction. Results show that NiCeOx-NP hybrid nanoparticles are effective for CO2 reforming reaction due to the ability of CeO2 to release and adsorb oxygen from CO2 during the alternating redox conditions. CuxO-NP and CuCeOx-NP have been chosen as model materials to catalyze methane combustion. This work describes a prototype methodology of facile synthesis of nanocatalysts with well-controlled characteristics, which can be used to establish the correlation of material properties versus reducibility and subsequent catalytic activity for a variety of energy and environmental applications.