Disassembly of Supported Co and Ni Nanoparticles by Carbon Deposition for the Synthesis of Highly Dispersed and Active Catalysts

Abstract

Supported cobalt and nickel nanoparticles are commonly used as catalysts in the modern chemical industry. Traditional methods of catalyst preparation such as impregnation or precipitation lead to the formation of relatively large metal nanoparticles (15-30 nm). The design of supported metal catalysts with higher dispersion is expected to result in major rate enhancement in many catalytic reactions. Hereby, we propose an efficient way to significantly increase the dispersion of metal catalysts by disassembling of supported metal nanoparticles using in situ polycondensation of aldehydes produced during dehydrogenation of fatty alcohols. Bulky polymers behave as surfactants, facilitating budding of smaller metal nanoparticles. Subsequent removal of carbon species by oxidative treatments results in smaller isolated metal nanoparticles with the sizes of about 2-7 nm and 3-6 times higher catalytic activity in hydrogenation, amination, and oxidation reactions. This method opens up the possibility of metal redispersion in both freshly prepared and deactivated catalysts.