摘要
CoO-MoO_3,NiO-MoO_3,CoO-WO_3,NiO-WO_3/Al_2O_3等催化剂在工业上广泛应用于加氢和脱硫过程,对于这类催化剂的研究大多针对此反应.当这类催化剂添加碱金属盐后对水煤气变换反应有明显的促进作用,而对加氢脱硫则显示出负效果.对于水煤气变换反应,这类催化剂最大的特点是能耐高浓度的硫,并具有低温活性.本工作对不同温度处理的NiO-MoO_3-K_2CO_3/Al_2O_3催化剂进行了XRD,XPS,DRS的研究,试图了解焙烧温度对催化剂结构,活性组分存在状态和分布以及催化活性的影响.
The effect of calcination on the activity and characteristics of NiO--MoO3-K2CO3/Al2O3 water gas shift catalyst has been investigated by XPS and DRS. The decrease of the relative content of surface Ni and the spinel NiAl2O4 structure formation was observed with increasing the calcination temperature, at the same time, the relative content of surface Mo remained unchanged and the relative content of surface K increased slightly in oxidic samples. After sulfidation the relative content of surface Ni further decreased. Reductive sulfidation of Mo and Ni became difficult after high temperature calcination as shown by XPS. The optimum calcination temperature was 400℃, at which the maximum promotive effect of Ni was obtained.
