Ni-Cu-Al2O3催化剂的活性相及作用机理

对新鲜和７００℃反应过的Ｎｉ－Ａｌ和Ｎｉ－Ｃｕ－Ａｌ催化剂的ＸＲＤ、ＸＰＳ表征结果表明，新鲜ＮｉＯ－Ａｌ２Ｏ３催化剂体相中的ＮｉＯ，ＮｉＡｌ２Ｏ４经７００℃反应后转变成金属Ｎｉ，同时表面的镍物种由单一的ＮｉＡｌ２Ｏ４变为ＮｉＡｌ２Ｏ４，ＮｉＯ和金属Ｎｉ的混合物，经反应后ＮｉＯ－ＣｕＯ－Ａｌ２Ｏ３催化剂体相和表相中的ＮｉＡｌ２Ｏ４，ＣｕＡｌ２Ｏ４均转变成为Ｎｉ－Ｃｕ合金，这是此催化剂对甲烷部分氧化反

Active Phase and Reaction Mechanism of Methane Partial Oxidation on Ni-Cu-Al_2O_3 Catalysts

XRD and XPS techniques have been applied to characterize the fresh and used NiO- CuO-Al2O3 at 700℃. NiO and NiAl2O4 in the bulk of fresh NiO-Al2O3 catalyst changed into metallic Ni during the reaction at 700℃; Meanwhile, NiAl2O4, the only hickel species on the surface, converted into a niture of NiAl2O4, NiO and metallic Ni in bulk and on surface. NiAl2O4 and CuAl2O4 are the existent phases in the fresh NiO-CuO-Al2O3 catalyst. During the reaction at 700℃, they changed into Ni-Cu metal cluster which is the active phase of Ni-Cu-Al catalyst for partial oxidation of methane. The promoter Cu facilitates the reduction of the nickel oxide and makes metallic Ni more suitable for methane partial oxidation. The atomic carbon produced on the surface of Ni-Al2O3 and Ni-Cu-Al2O3 catalysts during the reaction, indicates that the mode of methane activation is CH4→C+4H. Based on this phenomenon and the results of CH4+CO2, CH4+H2O, H2+CO2 reactions over Ni-Cu-Al2O3 catalyst, the pathway of the reaction has been summarized.