A nanometric Rh overlayer on a metal foil surface as a highly efficient three-way catalyst.
A nanometric Rh overlayer on a metal foil surface as a highly efficient three-way catalyst.
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DOI：
10.1038/srep29737
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发表时间：
2016-07-08
影响因子：
4.6
通讯作者：
Machida M
中科院分区：
文献类型：
--
作者：
Misumi S;Yoshida H;Hinokuma S;Sato T;Machida M
采用脉冲电弧等离子体（AP）在Fe-Cr-Al不锈钢箔上沉积Rh覆盖层，制备了具有高活性的汽车三元催化剂（TWC）复合材料。AP脉冲沉积了1-3 nm大小的金属Rh纳米颗粒，其在表面上的密度随着脉冲的数量而增加。这导致在箔表面上的聚结和晶粒生长，并最终形成均匀的二维Rh覆盖层。在1，000次脉冲后，实现了51 μ m厚的平箔被3.2 nm厚的Rh覆盖层完全覆盖。一个模拟的TWC反应使用了一个微型蜂窝结构，该蜂窝结构是用带有Rh覆盖层的平箔和波纹箔制成的，在实际的气体时空速度为1.2 × 105 h−1时，该反应表现出成功的点火。在金属蜂窝状催化剂上，NO-CO反应的转换频率约为100 Hz。80-比使用常规湿浸渍和浆料涂覆程序制备的参考Rh/ZrO 2涂覆的堇青石蜂窝体所获得的大一倍。尽管与传统的粉末催化剂（Rh/ZrO 2）相比，箔支撑的Rh覆盖层的无孔性和低表面积，但它是使用较少Rh负载的更有效的汽车催化剂的有前途的替代设计。
Pulsed arc-plasma (AP) deposition of an Rh overlayer on an Fe–Cr–Al stainless steel foil produced a composite material that exhibited high activity for automotive three-way catalysis (TWC). The AP pulses deposited metallic Rh nanoparticles 1–3 nm in size, whose density on the surface increased with the number of pulses. This led to coalescence and grain growth on the foil surface and the eventual formation of a uniform two-dimensional Rh overlayer. Full coverage of the 51 μm-thick flat foil by a 3.2 nm-thick Rh overlayer was achieved after 1,000 pulses. A simulated TWC reaction using a miniature honeycomb fabricated using flat and corrugated foils with the Rh overlayers exhibited successful light-off at a practical gaseous hourly space velocity of 1.2 × 105 h−1. The turnover frequency for the NO–CO reaction over the metallic honeycomb catalyst was ca. 80-fold greater than that achieved with a reference Rh/ZrO2-coated cordierite honeycomb prepared using a conventional wet impregnation and slurry coating procedure. Despite the nonporosity and low surface area of the foil-supported Rh overlayer compared with conventional powder catalysts (Rh/ZrO2), it is a promising alternative design for more efficient automotive catalysts that use less Rh loading.