[Zurück]

M. Grünbacher, A. Tarjomannejad, P. Kheyrollahi Nezhad, C. Praty, A. Mohammadi, A. Niaei, B. Klötzer, S. Schwarz, J. Bernardi, A. Farzi, M. Gómez, V. Torregrosa Rivero, S. Penner:
"Promotion of La(Cu0.7Mn0.3)0.98M0.02O3 d (M = Pd, Pt, Ru and Rh) perovskite catalysts by noble metals for the reduction of NO by CO";
Journal of Catalysis, 379 (2019), S. 18 - 32.

To evaluate the structural and spectroscopic steering factors of noble metal promotion in the catalytic
reduction of NO by CO, a series of La(Cu0.7Mn0.3)0.98M0.02O3 d (M = Pd, Pt, Ru, Rh) perovskite catalysts
is investigated. The materials are synthesized by a sol-gel method and characterized by X-ray powder
diffraction (XRD), electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). All metalpromoted
perovskites exhibit a comparatively higher activity for catalytic reduction of NO by CO with
respect to pure La(Cu0.7Mn0.3)O3 d . Among all catalysts tested, the La(Cu0.7Mn0.3)0.98Pd0.02O3 d perovskite
shows the highest catalytic activity, which is tentatively related to a combined synergistic effect of
improved oxygen vacancy activity and noble metals. Additionally, the redox chemistry of the catalysts
in different reducing (H2) and oxidizing (NO, O2) atmospheres is tested. An enhanced kinetic reducibility,
especially with Pd, was observed. All the H2-reduced catalysts are capable of reducing NO. At low and
intermediate temperatures, the formation of N2O is observed, but at higher temperatures NO is exclusively
converted to N2. The introduction of noble metals leads to new adsorption sites for NO. As XPS suggests
a tendency for depletion of noble metals in the surface-near regions, while the catalytic activity in
NO reduction at the same time appears much improved, directed noble metal promotion with modest
amounts especially in surface-near regions during synthesis appears as an encouraging method to economize
the use of the latter.

http://dx.doi.org/10.1016/j.jcat.2019.09.005