Effects of Hydrothermal Aging on CO and NO Oxidation Activity over Monometallic and Bimetallic Pt-Pd Catalysts

被引:22
作者
Schuetz, Jochen [1 ,3 ]
Stoermer, Heike [2 ]
Lott, Patrick [1 ]
Deutschmann, Olaf [1 ]
机构
[1] Karlsruhe Inst Technol KIT, Inst Chem Technol & Polymer Chem ITCP, D-76131 Karlsruhe, Germany
[2] Karlsruhe Inst Technol KIT, Lab Electron Microscopy LEM, D-76131 Karlsruhe, Germany
[3] Karlsruhe Inst Technol KIT, Engler Bunte Inst EBI, D-76131 Karlsruhe, Germany
关键词
aging; bimetallic catalyst; catalyst deactivation; diesel oxidation catalyst; palladium; platinum; DIESEL; PT/GAMMA-AL2O3; NANOPARTICLES; MOBILE; SIZE;
D O I
10.3390/catal11030300
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
By combining scanning transmission electron microscopy, CO chemisorption, and energy dispersive X-ray spectroscopy with CO and NO oxidation light-off measurements we investigated deactivation phenomena of Pt/Al2O3, Pd/Al2O3, and Pt-Pd/Al2O3 model diesel oxidation catalysts during stepwise hydrothermal aging. Aging induces significant particle sintering that results in a decline of the catalytic activity for all catalyst formulations. While the initial aging step caused the most pronounced deactivation and sintering due to Ostwald ripening, the deactivation rates decline during further aging and the catalyst stabilizes at a low level of activity. Most importantly, we observed pronounced morphological changes for the bimetallic catalyst sample: hydrothermal aging at 750 degrees C causes a stepwise transformation of the Pt-Pd alloy via core-shell structures into inhomogeneous agglomerates of palladium and platinum. Our study shines a light on the aging behavior of noble metal catalysts under industrially relevant conditions and particularly underscores the highly complex transformation of bimetallic Pt-Pd diesel oxidation catalysts during hydrothermal treatment.
引用
收藏
页码:1 / 18
页数:17
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