Enhancement of the Activities of γ-[Ga.sub.2][O.sub.3]-[Al.sub.2][O.sub.3] catalysts for methane-SCR of NO by treatment with N[H.sub.3]

• Published in: Catalysis letters Vol. 141; no. 9; pp. 1338 - 1344
• Main Authors: Watanabe, Tsunenori, Miki, Yoshihisa, Miyahara, Yuya, Masuda, Takeo, Deguchi, Hiroshi, Kanai, Hiroyoshi, Hosokawa, Saburo, Wada, Kenji, Inoue, Masashi
• Format: Journal Article
• Language: English
• Published: Springer 01-09-2011
• Subjects: Catalysts; Methane; Solid solutions; Spinel group
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-011-0654-7

The precursor particles for γ-[Ga.sub.2][O.sub.3]-[Al.sub.2][O.sub.3] solid solutions were prepared by the coprecipitation method from aqueous solutions of Ga[(N[O.sub.3]).sub.3] and Al[(N[O.sub.3]).sub.3] with [(N[H.sub.4]).sub.2]C[O.sub.3] as a precipitant. The γ-[Ga.sub.2][O.sub.3]-[Al.sub.2][O.sub.3] solid solutions were obtained by calcination of the precursor at 700 °C. In this paper, the performance of the catalysts treated with N[H.sub.3] was investigated for the selective catalytic reduction (SCR) of NO with methane as a reducing agent, and it was found that γ-[Ga.sub.2][O.sub.3]-[Al.sub.2][O.sub.3] catalysts treated with N[H.sub.3] and subsequently annealed in air showed higher activities than the γ-[Ga.sub.2][O.sub.3]-[Al.sub.2][O.sub.3] catalysts without N[H.sub.3] treatment. N[H.sub.3] treatment of the catalyst caused partial rearrangement of [Ga.sup.3+] and [Al.sup.3+] ions and increased the population of tetrahedral [Ga.sup.3+] ions in the defective spinel structure.