纳米Co_3O_4的制备及其在富氢气氛下CO选择氧化反应中的催化性能

过渡金属氧化物四氧化三钴(Co_3O_4)在CO氧化反应中展示了较好的低温活性.Co_3O_4催化剂用于富氢气氛下CO选择氧化反应已引起了人们极大的关注,具有潜在的应用前景.采用液相沉淀-热解氧化方法制备了2种不同形貌的纳米Co_3O_4.用X射线衍射(XRD)、扫描电子显微镜(SEM)等技术考察了包括沉淀剂种类、老化时间、焙烧温度等合成条件对生成Co_3O_4形貌、晶粒尺度的影响.制备的Co_3O_4的外形与沉淀前驱物外形直接相关.焙烧温度越高,Co_3O_4的颗粒越大.研究了制得的Co_3O_4在富氢气氛下CO选择氧化反应中的催化性能.对比以上方法制备的Co_3O_4的催化性能发现,催化剂的粒径和比表面积与催化剂的活性存在关联.使用尿素沉淀法并经250～300℃空气热解氧化制得的Co_3O_4具有较好的催化活性.

The Synthesis of Co_3O_4 Nanoparticles and Catalytic Performance of Carbon Monoxide Preferential Oxidation in H_2-rich Gas

The unsupported Co_3O_4 catalyst showed excellent low temperature CO oxidation activity.Its application for carbon monoxide preferential oxidation has attracted a great attention since it exhibited a potential prospect for industrial application.In this report,Co_3O_4 nanoparticles with two different kinds of morphologies were prepared by liquid-precipitation & air-oxidation pyrolysis method.In order to investigate the impact of preparation conditions (such as precipitating agents,aging time and calcination temperature) on the morphology and crystal size of Co_3O_4 nanoparticles,we used XRD,SEM to characterize the prepared Co_3O_4.Morphologies of Co_3O_4 are consistent with the morphology of their precipitation precursors.The higher the calcination temperature was,the larger the crystal size became.Catalytic preferential oxidation of carbon monoxide over Co_3O_4 nanoparticles in H_2-rich gas was performed.We compared the catalytic performance of Co_3O_4 synthesized by above methods,found that size and surface area of the catalyst had correlation with its catalytic activity.The Co_3O_4 obtained by urea-precipitation & air-oxidation method calcination at 250～300℃ exhibits the best activity.