Mesoporous Co3O4 with Controlled Porosity: Inverse Micelle Synthesis and High-Performance Catalytic CO Oxidation at-60 °C
Mesoporous Co3O4 with Controlled Porosity: Inverse Micelle Synthesis and High-Performance Catalytic CO Oxidation at-60 °C
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DOI：
10.1021/cm502106v
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发表时间：
2014-08-12
影响因子：
8.6
通讯作者：
Suib, Steven L.
中科院分区：
文献类型：
--
作者：
Song, Wenqiao;Poyraz, Altug S.;Suib, Steven L.
采用反相表面活性剂胶束法合成了具有高催化活性的介孔钴氧化物。所制备的材料是单分散的纳米颗粒聚集体，并且介孔由连接的颗粒内空隙形成。粉末X射线衍射（PXRD）、N-2吸附、场发射扫描电子显微镜（FE-SEM）和高分辨率透射电子显微镜（HR-TEM）显示，随着热处理温度的升高（150-450 ℃），孔和纳米颗粒尺寸都增大。在350 ℃下煅烧的介孔钴氧化物表现出最好的氧化活性，并且可以在-60 ℃下在正常条件下（类似于3-10 ppm的H2O）和在80 ℃下在富含水分的条件下（类似于3%H2O）实现CO到CO2的完全氧化（100%转化）。在正常条件下，商业Co 3 O 4在220 ℃下达到100%转化率。X射线光电子能谱（XPS）、程序升温脱附（O-2-TPD）、程序升温还原（H-2-TPR）、CO-TPD和N2吸附分析表明，催化剂表面的氧空位和大的比表面积促进了晶格氧的迁移，进一步提高了催化剂的催化性能。催化剂由于水的积累和碳酸盐的形成而失活，但它们的活性可以通过在中等温度（200 ℃）下排出水和碳酸盐而容易地恢复。
Crystalline mesoporous cobalt oxides with improved catalytic activity in CO oxidation were synthesized using an inverse surfactant micelle method. The prepared materials are monodispersed nanoparticle aggregates, and the mesopores are formed by connected intraparticle voids. Powder X-ray diffraction (PXRD), N-2 sorption, field emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) revealed that both pore and nanoparticle sizes are enlarged with increasing thermal treatment temperatures (150-450 degrees C). Mesoporous cobalt oxide calcined at 350 degrees C exhibited the best oxidation activity and can achieve complete oxidization (100% conversion) of CO to CO2 at -60 degrees C under normal conditions (similar to 3-10 ppm of H2O) and at 80 degrees C under moisture rich conditions (similar to 3% H2O). The commercial Co3O4 reached 100% conversion at 220 degrees C under normal conditions. X-ray photoelectron spectroscopy (XPS), O-2-temperature-programmed desorption (O-2-TPD), H-2-temperature-programmed reduction (H-2-TPR), CO-TPD, and N-2 sorption analyses indicated that the surface oxygen vacancy and large surface area promoted the lattice oxygen mobility of the catalysts and further enhanced their catalytic performance. The catalysts were deactivated by accumulation of water and formation of carbonates, but their activities can be easily restored by expelling water and carbonates at moderate temperature (200 degrees C).