Room temperature epoxidation of ethylene over delafossite-based AgNiO nanoparticles.

A mixed oxide of silver and nickel AgNiO was obtained co-precipitation in alkaline medium. This oxide demonstrates room temperature activity in the reaction of ethylene epoxidation with a high selectivity (up to 70%). Using the PDF method, it was found that the initial structure of AgNiO contains stacking faults and silver vacancies, which cause the nonstoichiometry of the oxide (Ag/Ni < 1).

Pd-Ceria/CNMs Composites as Catalysts for CO and CH Oxidation.

The application of composite materials as catalysts for the oxidation of CO and other toxic compounds is a promising approach for air purification. In this work, the composites comprising palladium and ceria components supported on multiwall carbon nanotubes, carbon nanofibers and Sibunit were studied in the reactions of CO and CH oxidation. The instrumental methods showed that the defective sites of carbon nanomaterials (CNMs) successfully stabilize the deposited components in a highly-dispersed state: PdO and CeO nanoparticles, subnanosized PdO and PdCeO clusters with an amorphous structure, as well as single Pd and Ce atoms, are formed.

Unraveling the low-temperature activity of Rh-CeO catalysts in CO oxidation: probing the local structure and Red-Ox transformation of Rh species.

The local structure of the active sites is one of the key aspects of establishing the nature of the catalytic activity of the systems. In this work, a detailed structural investigation of the Rh-CeO catalysts prepared by the co-precipitation method was carried out. The application of a variety of physicochemical methods such as XRD, Raman spectroscopy, XPS, TEM, TPR-H, and XAS revealed the presence of highly dispersed Rh species in the catalysts: Rh single ions and RhO clusters.

Pd-Ce-O/MWCNTs and Pt-Ce-O/MWCNTs Composite Materials: Morphology, Microstructure, and Catalytic Properties.

The composite nanomaterials based on noble metals, reducible oxides, and nanostructured carbon are considered to be perspective catalysts for many useful reactions. In the present work, multi-walled carbon nanotubes (MWCNTs) were used for the preparation of Pd-Ce-Ox/MWCNTs and Pt-Ce-Ox/MWCNTs catalysts comprising the active components (6 wt%Pd, 6 wt%Pt, 20 wt%CeO2) as highly dispersed nanoparticles, clusters, and single atoms. The application of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) provided analysis of the samples’ morphology and structure at the atomic level.

Mixed silver-nickel oxide AgNiO: Probing by CO during XPS study.

In this work, the reaction properties of mixed silver-nickel oxide AgNiO were investigated in the reaction of CO oxidation ranging from room temperature up to 350 °C. X-ray photoelectron spectroscopy revealed the presence of a single oxidized silver state and the combination of Ni and Ni species on the surface of the as-prepared mixed oxide. It was established that AgNiO was able to interact with CO at room temperature.

Tetraalkylammonium Salts of Platinum Nitrato Complexes: Isolation, Structure, and Relevance to the Preparation of PtO /CeO Catalysts for Low-Temperature CO Oxidation.

A series of tetraalkylammonium salts with anionic platinum nitrato complexes (MeN)[Pt(μ-OH)(NO)] (1), (EtN)[Pt(μ-OH)(NO)] (2), ( n-PrN)[Pt(μ-OH)(NO)] (3b), ( n-PrN)[Pt(NO)] (3a), and ( n-BuN)[Pt(NO)] (4) were isolated from nitric acid solutions of [Pt(HO)(OH)] in high yield. The structures of salts 2, 3a, 3b, and 4, prepared for the first time, were characterized by X-ray diffraction. The sorption of [Pt(NO)] and [Pt(μ-OH)(NO)] complexes onto the ceria surface from acetone solutions of salts 4 and 1 was examined.

Pt/CeO and Pt/CeSnO Catalysts for Low-Temperature CO Oxidation Prepared by Plasma-Arc Technique.

We applied a method of plasma arc synthesis to study effects of modification of the fluorite phase of ceria by tin ions. By sputtering active components (Pt, Ce, Sn) together with carbon from a graphite electrode in a helium ambient we prepared samples of complex highly defective composite PtCeC and PtCeSnC oxide particles stabilized in a matrix of carbon. Subsequent high-temperature annealing of the samples in oxygen removes the carbon matrix and causes the formation of active catalysts Pt/CeO and Pt/CeSnO for CO oxidation.