摘要
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℃反应后转变成为金属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应的活性相，助剂Cu的作用是促进氧化态镍的还原并调变金属Ni的化学性质，反应过的NiO－Al2O3、NiO－CuO－Al2O3催化剂表面上存在的原子态碳说明CH4的活化方式为红的逐步解离，在此基础上，根据NiO－CuO－Al2O3催化剂的CH4＋CO2、CH4＋H2O、H2＋CO2反应的结果。
XRD and XPS techniques have been applied to characterize the fresh and used NiO- CuO-Al2O3 at 700℃. NiOand 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 ekistent 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 okidation of methane. The promoter Cu facilitates the reduction of the nickel oalde 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.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1996年第5期429-435,共7页
Acta Physico-Chimica Sinica
基金
国家自然科学基金
关键词
甲烷
部分氧化
催化剂
活性相
镍
铜
氧化铝
Methane partial oxidation, NiO-CuO-Al_2O_3 Catalyst, Active phase, Reaction pathway
