Enhanced N2O decomposition on Rh/ZrO2 catalysts through the promotional effect of palladium

Abstract

Supported rhodium oxide (RhOx) catalysts have emerged as highly promising for effectively catalytic decomposition of N2O, hence contributing to the mitigation of greenhouse gas emission and combating global warming. Supported RhOx catalysts outperform catalysts employing zeolites and composite metal oxides even under challenging conditions involving O2, H2O, and CO2. This study explores the augmentation of Rh/ZrO2 (RhOx supported on monoclinic ZrO2) catalyst efficiency through the addition of palladium (Pd) to yield RhPd/ZrO2. The augmented catalyst demonstrates notable improvements in N2O decomposition under both N2O-only and more realistic conditions (N2O + O2 + H2O + CO2). Various techniques, including high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy, were employed to investigate the structural characteristics of Rh and Pd species on ZrO2. Kinetic studies further delved into the promotional effect, revealing that the introduction of Pd enhanced the catalytic activity of RhOx catalysts by augmenting their thermal reduction capability. This enhancement proved beneficial in facilitating the efficient progression of the rate-determining step for N2O catalytic decomposition, namely the thermal reduction of the catalyst to produce gaseous O2, particularly at low temperatures. These results highlight the potential of Pd-mediated improvements in Rh/ZrO2 catalysts for sustainable and efficient N2O decomposition.