State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
J Am Chem Soc. 2010 Mar 3;132(8):2608-13. doi: 10.1021/ja906274t.
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.
本文报道了具有高催化活性的介孔 Co(3)O(4)和 Au/Co(3)O(4)低温催化剂，可用于痕量乙烯在 0°C 下的氧化。催化剂采用纳米铸造法制备，介孔结构由三维（3D）立方 KIT-6 硅复制而成。高分辨率透射电子显微镜（HRTEM）研究表明，{110}晶面是介孔 Co(3)O(4)的暴露活性表面，而沉淀法制备的 Co(3)O(4 纳米片则显示出最暴露的{112}晶面。我们发现介孔 Co(3)O(4)在乙烯氧化中比 Co(3)O(4)纳米片具有更高的活性。结果表明，Co(3)O(4)的晶面{110}在决定其催化氧化性能方面起着重要作用。合成的 Au/Co(3)O(4)材料中，金纳米颗粒组装在 Co(3)O(4)介孔载体的孔壁上，表现出稳定、高度分散和暴露的金位。Co(3)O(4)上的金纳米颗粒容易产生表面活性氧物种，并促进乙烯氧化，在 0°C 下实现 76%的转化率，这是迄今为止报道的最高转化率。
