Roles of bulk γ(L)-Bi2MoO6 and surface β-Bi2Mo2O9 in the selective catalytic oxidation of C3H6

✍ Scribed by Takehiko Ono; Kazuya Utsumi; Satoshi Tsukamoto; Hiroyuki Tamaru; Masakazu Kataoka; Fumio Noguchi

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 844 KB
• Volume: 318
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/j.molcata.2009.11.012

✦ Synopsis

UV-vis spectra of Bi-Mo oxides Crystal structure visualization of Bi-Mo oxides Rapid oxygen transfer a b s t r a c t ␥(L)-Bi 2 MoO 6 (L: low temperature phase) catalysts, whose surface compositions have a Mo/Bi ratio above = 0.5, exhibited high selectivity in the partial oxidation of C 3 H 6 , while catalysts with Mo/Bi surface ratios near or below = 0.5 exhibited low selectivity. ␥(L)-phase catalysts which have Mo/Bi surface ratios greater than = 0.5, were demonstrated to form ␤-Bi 2 Mo 2 O 9 on their surface. An interaction between the ␤and ␥(L)-phases was observed in these catalysts' UV-vis spectra at 430 nm. The new ␤-phase material seems to grow along b-axis of ␥(L)-phase, i.e., perpendicular to MoO 2 -Bi 2 O 2 layers. Structure visualizations revealed that the ␣-Bi 2 Mo 3 O 12 , ␤-, and ␥(H)-phases, which are selective catalysts, contain twin Mo tetrahedral structures, and that their Mo and Bi ions lie on the same plane. The pure ␥(L)-phase does not contain this structure. A model for the very rapid transfer of oxygen between the ␥(L)and ␤-phases is discussed in relation to the kinetics of C 3 H 6 oxidation.