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Low-temperature catalysts of mesoporous Co (3) O (4) and Au/Co (3) O (4) with high catalytic activities for the trace ethylene oxidation at 0 degrees C are reported in this paper. The catalysts were prepared by using the nanocasting method, and the mesostructure was replicated from three-dimensional (3D) cubic KIT-6 silicas. High resolution transmission electron microscopy (HRTEM) studies revealed that 110 facets were the exposed active surfaces in the mesoporous Co (3) O (4), whereas the Co (3) O (4) nanosheets prepared by the precipitation method exhibited the most exposed 112 facets. We found that the mesoporous Co (3) O (4) was significantly more active for ethylene oxidation than the Co (3) O (4) nanosheets. The results indicated that the crystal facet 110 of Co (3) O (4) played an essential role in determining its catalytic oxidation performance. The synthesized Au/Co (3) O (4) materials, in which the gold nanoparticles were assembled into the pore walls of the Co (3) O (4) mesoporous support, exhibited stable, highly dispersed, and exposed gold sites. Gold nanoparticles present on Co (3) O (4) readily produced surface-active oxygen species and promoted ethylene oxidation to achieve a 76% conversion at 0 degrees C, which is the highest conversion reported yet.
Yan et al. (2010) studied this question.