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X‐ray diffraction studies of bismuth tungstate catalysts
Author(s) -
Sinhamahapatra Pratap Kumar,
Sinhamahapatra Samarendra,
Bhattacharyya Sudhir Kumar
Publication year - 1977
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.19770121113
Subject(s) - tungstate , bismuth , tetragonal crystal system , octahedron , catalysis , crystallography , selectivity , wolframite , tungsten , materials science , tetrahedron , diffraction , inorganic chemistry , chemistry , crystal structure , metallurgy , physics , optics , biochemistry
Abstract Bismuth tungstate catalysts with Bi/W ratios 2/3, 1/1, 2/1, and 6/1 have been investigated after various heat treatments by room temperature X‐ray analysis. The activity and selectivity of Bi 2 WO 6 catalyst are suggested to be connected with the presence of corner sharing W—O octhedra in the bulk of the solid that give rise to tetragonal pyramidal W—O sites at the surface. The very low activity of Bi 2 (WO 4 ) 3 is attributed to edge‐shared octahedral coordination of W while the same of Bi 6 WO 12 is due to tetrahedral coordination of W. The inactivity of Bi 2 W 2 O 9 may be associated with its typically low oxidation power. The promoting influence of Bi 2 O 3 is to enforce a structural situation on W—O so that W may be present in a tetragonal pyramidal 5‐configuration.