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Nanometric Platinum Overlayer to Catalyze NH3 Oxidation with High Turnover Frequency
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-03-25 , DOI: 10.1021/acscatal.0c00542
Masato Machida 1, 2 , Yurika Tokudome 3 , Akihide Maeda 3 , Yusuke Kuzuhara 3 , Taiki Hirakawa 3 , Tetsuya Sato 4 , Hiroshi Yoshida 1, 2 , Junya Ohyama 1, 2 , Kenji Fujii 5 , Naoya Ishikawa 5
Affiliation  

A pulsed cathodic arc-plasma deposition of a few-nanometer-thick Pt(111) overlayer on a 50 μm-thick Fe–Cr–Al metal foil produced a thin-film catalyst; this catalyst exhibited high activity for low-temperature NH3 oxidation and was superior to that of a conventional powder catalyst (Pt/Al2O3). A metal honeycomb that was fabricated using a metal foil catalyst successfully demonstrated a light-off performance at a practical gas hourly space velocity of 1.2 × 105 h–1. Despite its nonporosity and small surface area, the Pt overlayer is a promising alternative to Pt/Al2O3 for more efficient ammonia-slip catalysts that use less Pt loading; this is because the turnover frequency for the NH3 oxidation at 200 °C is more than 180-fold greater than that achieved with Pt/Al2O3 consisting of Pt nanoparticles. Although the nanometric Pt overlayer structure was thermally unstable at reaction temperatures of ≥600 °C, inserting a 250 nm-thick Zr buffer layer between the Pt overlayer and the metal foil substrate significantly mitigated the thermal deterioration. The undesired byproducts of NH3 oxidation, NO and NO2, can be efficiently converted to N2 by a selective catalytic reduction over a V2O5–WO3/TiO2 catalyst in a tandem reactor system.

中文翻译:

纳米白金覆盖层以高周转频率催化NH 3氧化

在厚度为50μm的Fe-Cr-Al金属箔上的几纳米厚的Pt(111)覆盖层的脉冲阴极电弧等离子体沉积产生了薄膜催化剂。该催化剂显示出对低温NH 3氧化的高活性,并且优于常规粉末催化剂(Pt / Al 2 O 3)。使用金属箔催化剂制造的金属蜂窝在实际气体时空速度为1.2×10 5 h –1的情况下成功展示了起燃性能。尽管无孔且表面积小,但Pt覆盖层是Pt / Al 2 O 3的有前途的替代品用于使用较少Pt负载的更高效的氨滑催化剂;这是因为在200°C下NH 3氧化的转换频率比由Pt纳米粒子组成的Pt / Al 2 O 3所获得的转换频率高180倍以上。尽管在≥600°C的反应温度下纳米级Pt覆盖层结构是热不稳定的,但在Pt覆盖层和金属箔基板之间插入250 nm厚的Zr缓冲层可以显着缓解热劣化。通过在V 2 O 5 –WO上进行选择性催化还原,可以将不需要的NH 3氧化副产物NO和NO 2有效转化为N 2串联反应器系统中的3 / TiO 2催化剂。
更新日期:2020-04-23
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