不同气氛下热处理对CO甲烷化催化剂性能的影响

采用液相包裹法制备了Ni/Al2O3耐高温甲烷化催化剂,并分别在静态空气、动态氮气及动态空气气氛条件下程序升温到550oC,恒温煅烧,得到不同气氛下热处理的三种催化剂。通过BET,H2-TPR,XPS等一系列的表征分析结果显示,经过动态气氛下煅烧的催化剂在高温和低温都具备良好的活性,其具有较大的比表面积,且流动性的气体可以有效的降低催化剂中镍与载体的结合力,主要表现在氧化镍的化学位能降低0.5eV,镍更易于还原

Effects of composite oxide supports on catalytic performance of Ni-based catalysts for CO methanation

采用改良的粉末混合法制备了系列经过其它金属氧化物改性的nIO/Al2O3催化剂,并运用X射线衍射、透射电子显微镜、n2低温物理吸附-脱附、程序升温还原、程序升温脱附、拉曼以及X射线光电子能谱对催化剂进行了表征.结果显示,在300~700OC经MgO修饰的nIO/Al2O3催化剂上CO甲烷化反应活性比nIO/zrO2-Al2O3和nIO/SIO2-Al2O3的高.另一金属氧化物的加入削弱了nIO/Al2O3催化剂中nI-Al间相互作用,形成更多的活性nI物种,从而促进了反应的进行.Metal-oxide-modified NiO/Al2O3 catalysts for methanation of CO were prepared using a modified grinding-mixing method and characterized using X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms, temperature-programmed reduction by H2, temperature-programmed desorption by H2, Raman spectroscopy, and X-ray photoelectron spectroscopy.The results show that the activity of an MgO-modified NiO/Al2O3 catalyst is better than those of NiO/ZrO2-Al2O3 and NiO/SiO2-Al2O3 in the reaction temperature range 300–700 °C.The incorporation of a metal oxide into NiO/Al2O3 was found to weaken Ni–Al interactions, leading to generation of large numbers of active Ni species, and this was confirmed to be responsible for the improvement in the performances of the catalysts in the methanation reaction.supportedbytheNationalBasicResearchProgramofChina(973Program;2010CB226903)~