Catalytic behavior of AMoO{sub x} (A = Ba, Sr) in oxidation of 2-propanol

• Published in: Materials research bulletin Vol. 44; no. 4
• Main Authors: Kubo, Jun, Ueda, Wataru
• Format: Journal Article
• Language: English
• Published: United States 02-04-2009
• Subjects: ACETONE; AMMONIA; ATMOSPHERIC PRESSURE; BARIUM COMPOUNDS; CATALYSTS; DEHYDRATION; DEHYDROGENATION; MATERIALS SCIENCE; MOLYBDENUM IONS; MOLYBDENUM OXIDES; OXIDATION; OXYGEN; PEROVSKITE; PROPANOLS; PROPYLENE; REDUCTION; SCANNING ELECTRON MICROSCOPY; STRONTIUM COMPOUNDS; SYNTHESIS; X-RAY DIFFRACTION
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2008.08.013

Perovskite-type oxides, BaMoO{sub 3} and SrMoO{sub 3}, were prepared by reduction of scheelite-type oxides, BaMoO{sub 4} and SrMoO{sub 4}, in H{sub 2} flow at 873 K and characterized by XRD, TG, SEM, TPR, NH{sub 3}-TPD, UV-vis DRS and BET measurement. The catalytic activity of these alkaline-earth molybdenum oxide catalysts was tested for oxidation of 2-propanol with gaseous oxygen under atmospheric pressure. Dehydration to propylene was mainly promoted over the scheelite-type with Mo{sup 6+}, while oxidative dehydrogenation to acetone was mainly promoted over the perovskite-type with Mo{sup 4+}, and selectivity to acetone was much higher over BaMoO{sub 3} than over SrMoO{sub 3}. Both perovskite-type oxide catalysts underwent oxidation to some degree during the catalytic reaction, so that they also contained some Mo{sup 6+}. We concluded that the high selectivity to acetone resulting from oxidative dehydrogenation during 2-propanol conversion is related to the constantly changing oxidation state of the catalyst, resulting in coexistence of Mo{sup 6+} octahedra and Mo{sup 4+} octahedra on the AMoO{sub 3} oxides.