Abstract
In this study, we demonstrate the preparation and characterization of small palladium nanoparticles (Pd NPs) on modified ceria support (Pd/CeO2) using wet impregnation and further reduction in an H2/Ar flow. The obtained particles had a good dispersion, but their small size made it difficult to analyze them by conventional techniques such as transmission electron microscopy (TEM) and X-ray powder diffraction (XRPD). The material demonstrated a high catalytic activity in the CO oxidation reaction: the 100% of CO conversion was achieved at ~50 °C, whereas for most of the cited literature, such a high conversion usually was observed near 100 °C or higher for Pd NPs. Diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy in combination with CO probe molecules was used to investigate the size and morphology of NPs and the ceria support. On the basis of the area ratio under the peaks attributed to bridged (B) and linear (L) carbonyls, high-dispersion Pd NPs was corroborated. Obtained results were in good agreement with data of X-ray absorption near edge structure analysis (XANES) and CO chemisorption measurements.
Highlights
Supported noble-metal nanoclusters are well-known catalysts for diverse hydrogenation and oxidation reactions, in CO oxidation
We present the synthesis of supported palladium nanoparticles (Pd NPs) using a modified surface of cerium dioxide
Of Pd loading a homogeneous distribution of palladium on a ceria support obtained by means of synthesized sample, which was slightly less than the theoretical value of 4 wt%
Summary
Supported noble-metal nanoclusters are well-known catalysts for diverse hydrogenation and oxidation reactions, in CO oxidation. A number of attempts [1,2,3,4,5,6,7,8] were made to synthesize a catalyst on the basis of supported NPs with a high activity at low temperatures. The catalytic activity of NPs depends on the size and shape of the NPs [9], the material of the support [10] and the functionalization [11] and composition [12]. One of the most crucial factors for an advanced catalytic activity is a high dispersion and uniform distribution over the support surface [13]. One of the ways to meet this requirement is the use of modified matrix surfaces to support NPs. Guo et al [14] described the method of deposition of Pd on a SiO2 substrate. Silica gel was synthesized in situ with simultaneous surface modification by introducing 3-aminopropyltriethoxysilane into the Catalysts 2019, 9, 385; doi:10.3390/catal9040385 www.mdpi.com/journal/catalysts
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