Low Temperature CO Oxidation Over a Novel Nano-Structured, Mesoporous CeO2 Supported Au Catalyst

Dealloying Synthesis of Bimetallic (Au-Pd)/CeO2 Catalysts for CO Oxidation

The nanorod-structured (Au-Pd)/CeO₂ catalysts with different Au/Pd ratios were prepared from Al-Ce-Au-Pd precursor alloys through combined dealloying and calcination treatment. XRD, SEM, TEM, XPS, Raman spectroscopy, and N₂ adsorption-desorption measurements were applied to test the structure and physicochemical properties of samples. Catalytic evaluation results imply that the (Pd_0.15-Au_0.15)/CeO₂ catalyst calcined at 500 °C possesses optimal catalytic activity for CO oxidation when compared with other catalysts with different Au/Pd ratios or (Pd_0.15-Au_0.15)/CeO₂ calcined at other temperatures, whose 50% and 99% reaction temperature can be reached as low as 50 and 85 °C, respectively. This superior catalytic property is attributed to their robust nanorod structure and the introduction of noble bimetal Pd and Au, which can construct a nanoscale interface to access fast electron motion, thus enhancing catalytic efficiency.

Microwave-assisted synthesis of gold nanoparticles supported on Mn3O4 catalyst for low temperature CO oxidation

In the present work, Mn₃O₄ was prepared by various methods and successfully loaded with metallic Au nanoparticles reduced by hydrazine hydrate using microwave irradiation (MWI) method. The surface morphology and composition of the prepared samples were characterized with X-ray diffraction (XRD), N₂ adsorption-desorption, temperature programmed reduction (H₂-TPR), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that no significant changes in some textural and structural properties of the samples due to preparation method or Au nanoparticles deposition. While the surface composition and reducibility of the samples were greatly affected by preparation method and Au deposition. The CO oxidation reaction over the samples was selected as a model reaction to study the relation between surface properties of the samples and their catalytic performance. The results showed that a direct proportionality exists between the reducibility and the CO oxidation activity of catalysts. The kinetic study of the reaction showed that the reaction is first order. Moreover, the samples exhibited good stability in CO oxidation at 100% conversion for around 30 h under the reaction conditions.

Sensitive Carbon Monoxide Gas Sensor Based on Chemiluminescence on Nano-Au/Nd2O3-Ca3Nd2O6: Working Condition Optimization by Response Surface Methodology

An Au/Nd₂O₃-Ca₃Nd₂O₆ composite was synthesized by the sol-gel and impregnation method. The EDS spectrum and the transmission electron microscopy image showed that Au atoms are uniformly distributed on the surface of Nd₂O₃-Ca₃Nd₂O₆ with a size of less than 50 nm. A sensitive carbon monoxide gas sensor based on chemiluminescence at a temperature lower than 200 °C was reported. There is a good linear relationship between the chemiluminescence intensity and the concentration of carbon monoxide in the range of 0.6-125 mg/m³. The detection limit (3σ) is 0.2 mg/m³. The working conditions optimized by the response surface methodology were an analytical wavelength of 620.90 nm, a reaction temperature of 131.63 °C, and a carrier-gas velocity of 105.46 mL/min. The sensitivity of the method can be increased by 4.5% under the optimized working conditions, which is especially important for the determination of trace substances. The carbon monoxide sensor demonstrated in this paper can be used for practical applications. The optimization method is universal for many multiparameter processes.

One-pot synthesis of Au–Fe2O3@SiO2 core–shell nanoreactors for CO oxidation

The combination of the Au–Fe₂O₃ phase and core–shell structure helps in achieving high activity and good thermal stability.