Syngas production through dry reforming of ethanol over Co@SiO2 catalysts: Effect of SiO2 shell thickness

Abstract

Morphology structure is regarded as one of the key factors in developing highly efficient catalysts for heterogeneous catalytic reactions. In this work, the influence of SiO2 shell thickness on the performance of the Co@SiO2 catalysts in ethanol dry reforming was studied in detail. Indeed, the different shell thickness resulted in various strengths of metal-support interactions for the Co@SiO2 catalysts, thereby greatly affecting the activity/stability. Herein, Co@SiO2–1.5 sample with ca.20 nm shell thickness exhibited better physicochemical properties. The Oads/Olatt ratio of Co@SiO2–1.5 (1.03) was higher than that of Co@SiO2–1 (0.75) and Co@SiO2–2.5 (0.91) as depicted in XPS spectra. Oads sites were indexed with the activated O species originated from O defects. On the other hand, the highest performance was obtained over Co@SiO2–1.5 sample with the optimal shell thickness as well as strong metal-support interaction. Particularly, 100% of ethanol conversion was achieved at 550 °C for Co@SiO2–1.5 catalyst and the targeted H2/CO ratio was closer to 1 compared to other samples. In addition, no obvious deactivation (ethanol conversion still be 100%) occurred after 40 h time on stream tests. This finding might depict a general strategy to design/develop the attractive catalysts with the core/shell structure for other heterogeneous reactions.