Sandwich-type Co core@shell nanocomposite (SiO2 @Co@CeO2): Coke resistant catalyst toward CO2 reforming with ethanol

The design of highly efficient catalysts for CO2 reforming with ethanol is of great interest due to the serious coke deposition and the sintering of active metal. In this work, sandwich-type Co core@shell catalyst (SiO2 @Co@CeO2) with Co nanoparticles between SiO2 core and CeO2 shell was synthesized by strong electrostatic adsorption method. Interestingly, SiO2 @Co@CeO2 catalyst exhibited the outstanding activity/stability toward CO2 reforming of ethanol in comparison with Co-SiO2 catalyst. A bi-functional mechanism involving active sites on CeO2 shell was proposed. Indeed, cobalt nanoparticles between SiO2 core and CeO2 shell maintained the high dispersion because of the confinement effect, which supplied a stable Co-ceria interface area where the reaction occurred. In addition, CO2 could readily react with the O vacancies in CeO2 shell to form surface oxygen species and CO, which allowed a continuous cleaning of coke. These positive factors could make it as an attractive candidate for dry reforming process.