Superior performance of Ir-substituted hexaaluminate catalysts for N2O decomposition

✍ Scribed by Shaomin Zhu; Xiaodong Wang; Aiqin Wang; Tao Zhang

• Book ID: 104009788
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 972 KB
• Volume: 131
• Category: Article
• ISSN: 0920-5861
• DOI: 10.1016/j.cattod.2007.10.093

✦ Synopsis

Novel Ir-substituted hexaaluminate catalysts were developed for the first time and used for catalytic decomposition of high concentration of N 2 O. The catalysts were prepared by one-pot precipitation and characterized by X-ray diffraction (XRD), N 2 -adsorption, scanning electronic microscopy (SEM) and temperature-programmed reduction (H 2 -TPR). The XRD results showed that only a limited amount of iridium was incorporated into the hexaaluminate lattice by substituting Al 3+ to form BaIr x Fe 1Àx Al 11 O 19 after being calcined at 1200 8C, while the other part of iridium existed as IrO 2 phase. The activity tests for high concentration (30%, v/v) of N 2 O decomposition demonstrated that the BaIr x Fe 1Àx Al 11 O 19 hexaaluminates exhibited much higher activities and stabilities than the Ir/Al 2 O 3 -1200, and the pre-reduction with H 2 was essential for activating the catalysts. By comparing BaIr x Fe 1Àx Al 11 O 19 with BaIr x Al 12Àx O 19 (x = 0-0.8), it was found that iridium was the active component in the N 2 O decomposition and the framework iridium was more active than the large IrO 2 particles. On the other hand, Fe facilitated the formation of hexaaluminate as well as the incorporation of iridium into the framework.