Bimetallic AuPd@CeO2 Nanoparticles Supported on Potassium Titanate Nanobelts: A Highly Efficient Catalyst for the Reduction of NO with CO

Abstract

A nanocomposite consisting of bimetallic AuPd nanoparticles, which were modified with CeO2 (AuPd@CeO2), and deposited on potassium titanate nanobelts (KTN) as support, is shown to exhibit outstanding catalytic performance in the selective catalytic reduction of NO with CO. Transmission electron microscopy and energy dispersive X-Ray elemental mapping indicated that the AuPd nanoparticles surrounded by CeO2 were well-mixed forming an alloy. The potassium titanate support consisted of 1–3 µm long and 8–14 nm wide nanobelts. The AuPd@CeO2/KTN catalyst showed full NO conversion at 100 % selectivity to N2 at a gas-hourly space velocity (GHSV) of 15,000 h−1 and 200 °C. The outstanding performance of the AuPd@CeO2/KNT catalyst is attributed to favorable synergies between its components. Corresponding monometallic Au catalysts supported on KTN (Au@CeO2/KNT), as well as bimetallic AuPd supported on TiO2 (AuPd@CeO2/TiO2), showed inferior catalytic performance, indicating the absence of a beneficial synergy between the different components. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with modulation excitation spectroscopy (MES) proved that alloying of Au with Pd enhances the ability to adsorb CO and NO on the surface in an on-top configuration and that the deposition of the bimetallic AuPd nanoparticles on KTN facilitates the crucial formation of isocyanate (-NCO) species, resulting in high conversion and selectivity.