MO$_x$@VO$_x$-Pd‐type Nanorods and Nanotubes as Catalysts for Selective Reduction of NO

Vanadium oxide (VO$_x$-Pd) nanotubes as well as VO$_x$-coated ZnO nanorods (ZnO@VO$_x$-Pd) and VO$_x$-coated, layered-titania nanotubes (l-TiO$_2$@VO$_x$-Pd) are decorated with Pd nanoparticles and evaluated for selective catalytic reduction with hydrogen (H$_2$-SCR) for the first time. The nanostructures exhibit lengths of 300 to 700 nm, diameters of 20–100 nm and, in the case of the nanotubes, an inner tube diameter of about 10 nm. Pd nanoparticles (14±5 nm) are well-dispersed over the respective nanorod/nanotube nanostructure. Structure and composition are characterized by SEM, TEM, EDXS with element mapping, XPS, FT-IR, XRD, and sorption analysis. Thermal analysis indicates the nanostructures to be thermally stabile up to 350 °C (VO$_x$), and 500 °C (ZnO@VO$_x$, l-TiO$_2$@VO$_x$). All catalysts are tested for their activity in regard of the selective catalytic reduction of NO with H$_2$, revealing a significant impact of the catalyst support on both activity and selectivity. Specifically, l-TiO$_2$@VO$_x$ nanotubes show promising properties with an activity up to 70 % and a selectivity up to 80 % N$_2$.