Inomata Yusuke, Kubota Hiroe, Hata Shinichi, Kiyonaga Eiji, Morita Keiichiro, Yoshida Kazuhiro, Sakaguchi Norihito, Toyao Takashi, Shimizu Ken-Ichi, Ishikawa Satoshi, Ueda Wataru, Haruta Masatake, Murayama Toru
Research Center for Gold Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University Hachioji, Tokyo, 192-0397, Japan.
Institute for Catalysis, Hokkaido University, Sapporo, Hokkaido, 001-0021, Japan.
Nat Commun. 2021 Jan 25;12(1):557. doi: 10.1038/s41467-020-20867-w.
NH-SCR (selective catalytic reduction) is important process for removal of NOx. However, water vapor included in exhaust gases critically inhibits the reaction in a low temperature range. Here, we report bulk W-substituted vanadium oxide catalysts for NH-SCR at a low temperature (100-150 °C) and in the presence of water (~20 vol%). The 3.5 mol% W-substituted vanadium oxide shows >99% (dry) and ~93% (wet, 5-20 vol% water) NO conversion at 150 °C (250 ppm NO, 250 ppm NH, 4% O, SV = 40000 mL h g). Lewis acid sites of W-substituted vanadium oxide are converted to Brønsted acid sites under a wet condition while the distribution of Brønsted and Lewis acid sites does not change without tungsten. NH species adsorbed on Brønsted acid sites react with NO accompanied by the reduction of V sites at 150 °C. The high redox ability and reactivity of Brønsted acid sites are observed for bulk W-substituted vanadium oxide at a low temperature in the presence of water, and thus the catalytic cycle is less affected by water vapor.
氨选择性催化还原（NH-SCR）是去除氮氧化物的重要过程。然而，废气中所含的水蒸气在低温范围内会严重抑制该反应。在此，我们报道了用于低温（100 - 150°C）且存在水（约20体积%）情况下的块状钨取代钒氧化物NH-SCR催化剂。3.5摩尔%的钨取代钒氧化物在150°C（250 ppm NO、250 ppm NH、4% O、空速 = 40000 mL h g）时显示出>99%（干燥）和约93%（潮湿，5 - 20体积%水）的NO转化率。在潮湿条件下，钨取代钒氧化物的路易斯酸位点会转变为布朗斯特酸位点，而没有钨时，布朗斯特酸位点和路易斯酸位点的分布不变。在150°C时，吸附在布朗斯特酸位点上的NH物种与NO反应，同时钒位点被还原。在低温且存在水的情况下，块状钨取代钒氧化物表现出高氧化还原能力和布朗斯特酸位点的反应活性，因此催化循环受水蒸气的影响较小。
