Mo-Ni/γ-Al_2O_3甲烷化催化剂研究(Ⅱ)制备条件及还原条件对催化剂结构的影响

Study on Mo-Ni/γ-Al_2O_3 Methanation Catalysts (Ⅱ) The Effects of Preparation and Reduction Conditions on the Surface Structure

用程序升温还原 ( TPR)、程序升温脱附 ( TPD)、X射线粉末衍射 ( XRD)及透射电子显微镜 ( TEM)等法对分步浸渍法制备的一系列 Mo-Ni/ γ-Al2 O3甲烷化催化剂的结构进行了表征 .考察了浸渍液的 p H值、焙烧温度及还原温度对催化剂的表面结构的影响 .结果表明∶先浸 Mo时 ,调 ( NH4 ) 6Mo7O2 4 溶液的 p H=3、浸 Mo后 50 0℃焙烧的催化剂易于还原 ,而且能抑制后浸 Ni时 ,难还原铝酸盐的形成 ;浸 Ni时 ,调 Ni( NO3) 2 溶液的 p H=8,浸后 4 30℃焙烧的催化剂易于还原 ;浸 Mo后 ,650℃焙烧易形成难还原的 Al2 ( Mo O4 ) 3,浸 Ni后 530℃焙烧的催化剂易形成难还原的 Ni Al2 O4 与类 Ni Al2 O4 铝酸盐 .催化剂于 50 0℃还原时 ,还原态的 Ni最多 ,4 50℃还原时有利于

A series of Mo Ni/γ Al 2O 3 Methanation Catalysts were prepared by impregnation in sequence. Their structures were characterized with methods of TPR,TPD,XRD and TEM. The effects of pH of impregnation solution ,calcination temperature and reduction temperature on the surface structure were investigated. It was showed that: the catalyst prepared in this way that pH=3 of (NH 4) 6Mo 7O 24 solution during impregnating Mo and calcinated at 500℃; Secondly pH=8 of Ni(NO 3) 2 solution during impregnating Ni and calcinated at 430℃ was easy to be reduced .The catalyst tended to formate Al 2(MoO 4) 3 when calcinated at 650℃ after impregnating Mo ,and formate NiAl 2O 4 and like NiAl 2O 4 when calcinated at 530 ℃ after impregnating Ni .The two compounds were both difficult to be reduced .The catalyst had more Ni in reduced state when reduced at 500℃,but was suitable for the formation of Mo Ni alloy when reduced at 450℃.