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■■■■■■■■■■■■■■■■■■■ 川崎製鉄技報 KAWASAKI STEEL GIHO Vol.11 (1979) No.2 ■■■■■■■■■■■■■■■■■■■ |
| 酸化鉄を用いた排煙脱硝触媒の特性および性能 Properties and Performances of Various Iron Oxide Catalysts for the Reduction of Nitric Oxide with NH3 成瀬 義弘(Yoshihiro Naruse) 小笠原 武司(Takeshi Ogasawara) 畑 俊彦(Toshihiko Hata) |
| 要旨 : 製鉄所の廃酸処理工程の副生酸化鉄を排煙脱硝触媒に用いることを検討した。酸化鉄粒子の特性は従来法で測定し，活性試験は常圧流通報で250°〜400℃で行った。結果を次に示す。(1) 0.5t/cm2で成型した触媒の細孔容積，平均細孔半径，比表面積はそれぞれ0.185〜0.545cm3/g, 160〜791Å, 8.8〜71.3m2/g であった。(2) 触媒の活性と比表面積には単純な関係は認められなかったが，ゲーサイト系の触媒では活性が比表面積にほぼ比例して減少した。(3) 触媒性能は硫酸第2鉄として存在すると考えられる硫酸根の初期含有量に依存した。(4) 2, 3 の酸化鉄はFeSO4, V2O5などを坦持すれば担体としても用いうる。坦持した触媒ではV2O5/Fe2O3が最高の活性を示した。(5) NH3によるNOの還元反応はほぼ1次反応で表され，律速段階は触媒細孔内NOの拡散過程であった。 |
| Synopsis : A study was made to apply iron oxides obtained as by-products in the treatment proceses of waste pickle liquor in steel works to catalysts for the reduction of nitric oxide with ammonia. The characteristics of various kinds of α-Fe2O3 particles were measured by conventional methods and the catalytic activity was tested by using a flow reactor (ID.: 26mm) under atmospheric pressure at 250°〜400℃. Pore volume, mean pore radius, and surface area of these catalysts (compacting pressure: 0.5t/cm**2) ranged from 0.185〜0.545cm**3/g, 160〜791Å, and 8.8〜71.3m**2/g, respectively. There was no simple relationship between catalytic activity and surface area in these catalysts. However, when the catalysts were prepared from α-FeOOH, the catalytic activity decreased with an increase of the surface area. The activity and selectivity of these catalysts depended on the initial content of SO4 which was considered to exist as iron (V）sulfate. A few kinds of α-Fe2O3 could be used as a catalyst support by supporting FeSO4, V2O5 and so on. In these supportes catalysts, V2O5/Fe2O3 had the highest activity. The rate of NO reduction with NH3 was roughly showed as a first order reaction with NO, and the rate-controlling step was the diffusion of the reactant through the catalyst pores. |
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