Thermal Evolution of the Structure and Activity of Rh Overlayer Catalysts Prepared by Pulsed Arc-Plasma Deposition
Thermal Evolution of the Structure and Activity of Rh Overlayer Catalysts Prepared by Pulsed Arc-Plasma Deposition
复制标题
DOI：
10.1007/s11244-017-0760-x
复制
发表时间：
2017-04
影响因子：
3.6
通讯作者：
S. Misumi;H. Yoshida;A. Matsumoto;S. Hinokuma;Tetsuya Sato;M. Machida
中科院分区：
文献类型：
--
作者：
S. Misumi;H. Yoshida;A. Matsumoto;S. Hinokuma;Tetsuya Sato;M. Machida
采用脉冲阴极电弧等离子体（AP）技术在Fe-Cr-Al不锈钢（SUS）表面制备了纳米Rh覆盖层，研究了其结构的热演化和化学计量比NO-CO-C3 H6-O2反应的催化活性.在2000-8000 AP脉冲下，制备的Rh/SUS催化剂在250 °C左右对NO、CO和C3 H6具有陡峭的起燃，转化率很快达到近100%。在900 °C的H2O/空气中热老化后，催化剂的活性随AP脉冲次数的不同而不同程度地降低。在最小AP脉冲数（2000）下观察到最显著的失活，因为箔中的Al在老化期间被氧化以形成α-Al 2 O3钝化层，其覆盖箔的表面并降低Rh的表面浓度。为了克服这种失活，在空气中在1000 °C下预热箔之后通过AP形成Rh覆盖层。这种改进的制备工艺使得Rh覆盖层能够沉积在箔表面的高度结晶的α-Al 2 O3层上，发现其对热失活更加稳定。
Nanometric Rh overlayers were formed on Fe–Cr–Al stainless steel (SUS) foils by pulsed cathodic arc-plasma (AP) technique to investigate the thermal evolution of the structure and catalytic activity for stoichiometric NO–CO–C3H6–O2reaction. As-prepared Rh overlayer catalysts (Rh/SUS) with 2000–8000 AP pulsing showed steep light-off of NO, CO and C3H6at around 250 °C and their conversions soon reached to almost 100%. After thermal aging at 900 °C in H2O/air, however, the catalytic activity was decreased to the different extent depending on the number of AP pulsing. The most significant deactivation was observed for the smallest numbers of AP pulsing (2000), because Al in the foil was oxidized during the aging to form a passivation layer of α-Al2O3, which covered the surface of the foil and decreased the surface concentration of Rh. To overcome this deactivation, the Rh overlayer was formed by AP after preheating the foil at 1000 °C in air. This modified preparation process enables the deposition of Rh overlayer on the highly crystalline α-Al2O3layer at the surface of the foil, which is found to be much more stable against thermal deactivation.