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New Insights into the Role of Al 2 O 3 in the Promotion of CuZnAl Catalysts: A Model Study
Author(s) -
Hu Jun,
Song Yanying,
Huang Junjie,
Li Yangyang,
Chen Mingshu,
Wan Huilin
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201701697
Subject(s) - ternary operation , catalysis , materials science , layer (electronics) , copper , deposition (geology) , crystallography , zinc , analytical chemistry (journal) , metallurgy , nanotechnology , chemistry , paleontology , biochemistry , chromatography , sediment , computer science , biology , programming language
The Cu/Al 2 O 3 /ZnO(0001)‐Zn ternary model catalysts and their binary analogues were prepared and characterized. It was found that Al 2 O 3 grew on the ZnO(0001)‐Zn surface by a layer‐by‐layer model, whereas Cu grew on the ZnO(0001)‐Zn surface as two‐dimensional clusters up to 0.2 monolayers (ML), and thereafter formed three‐dimensional clusters. Because of the layer‐by‐layer growth of Al 2 O 3 on the ZnO(0001)‐Zn, Cu/Al 2 O 3 can be considered without the effect of ZnO. Ternary model catalyst Cu/Al 2 O 3 /ZnO(0001)‐Zn, which has all three parts on the surface, was prepared by deposition of Cu on the surface of Al 2 O 3 /ZnO(0001)‐Zn. Low‐energy ion scattering spectra showed that Cu preferred to locate at the Al 2 O 3 /ZnO interfaces. Compared with Cu/ZnO, the addition of Al 2 O 3 obviously suppressed the reduction of copper oxides and led to a higher concentration of Cu + . The Cu clusters were found to be covered by thin ZnO x overlayers after reduction of Cu/Al 2 O 3 /ZnO(0001)‐Zn by using H 2 . Therefore, the high activity of industrial Cu/ZnO/Al 2 O 3 catalysts may origin from Cu + ‐rich clusters at the Al 2 O 3 /ZnO interface that are covered by thin ZnO x overlayers.