Understanding the key parameters for the rational design of layered oxide materials by composite sol-gel procedures

Previous works have well demonstrated that particle size of the filler used in layered oxide formulation is the first important parameter and must be decreased below 5 μm (Agrafiotis, 1999-2000 [10]). But once the particle size is set what are the next formulation parameters to highlight as critical? How do we improve cohesion and adhesion of the coatings? To highlight the key parameters driving the quality of coating, a model layered oxide material was prepared inside a pan granulator. The model composite sol gel formulation is based on boehmite nanoparticles (binder) and amonomodal two micrometer grain size gamma alumina (filler) which is applied onto alpha alumina beads substrate. The influences of the wetting method and relative amount of filler and binderwere investigated. Extensive characterization and imaging of the layered materials (SEM, Cryo-SEM, EPMA, Washburn test, mechanical tests, Hg-porosimetry) were used in order to follow the microstructure evolution of coating during and at the end of drying. Several crack propagation schemes were observed and explained qualitatively. Overall quality of coating is mainly related to the sol-gel transition of the binder. It defines if prior to shaping, the binder primer will be able to improve the coating adhesion and it defines also the nature and extent of damages that the coating undergoes during drying. The mechanical properties of layered oxide materials obtained using composite sol-gel formulation are definitely correlated with the binder gel shrinkage during drying

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Synthesis and Characterization of Co3O4 nanocubes with exposed {001} Facets as a Water Oxidation Catalyst

Internationa

Synthesis and Characterization of Co3O4 nanocubes with exposed {001} Facets as a Water Oxidation Catalyst

Internationa

New approach to preparation of nitrogen doped titania for visble range phtotocatalytic hydrogen production

International @ RAFFINAGE+EPU:CGE:PAFNon

In situ/operando techniques for characterization of supported metal single-atom catalysts

This chapter presents the advances concerning in situ and operando characterization studies of supported single-atom catalysts (SAC), covering general information on the techniques which are currently used, and reviewing the range of recently published results that explore the understanding of both synthesis and structure-properties relationship. X-ray Absorption Spectroscopy is widely used since it is element specific and is able to study oxidation state, and bonding of metal atoms to ligands. Several IR studies are also present in the literature studying the bands associated with absorption of CO and the recent development of ambient pressure X-ray Photoelectron spectroscopy is promoting an increasing use of the technique. Electron microscopy techniques are used to probe supported SAC on an atomic scale, whether by imaging of structure, or by spectroscopic chemical analysis. The challenge of applying these techniques when the sample is not in a vacuum means that only a limited number of studies are available. Many of the recent studies show the advantages of combining more than one of these techniques

Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres.

X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities-to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions-to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported

The comparison between single atom catalysis and surface organometallic catalysis

Single atom catalysis (SAC) is a recent discipline of heterogeneous catalysis for which a single atom on a surface is able to carry out various catalytic reactions. A kind of revolution in heterogeneous catalysis by metals for which it was assumed that specific sites or defects of a nanoparticle were necessary to activate substrates in catalytic reactions. In another extreme of the spectrum, surface organometallic chemistry (SOMC), and, by extension, surface organometallic catalysis (SOMCat), have demonstrated that single atoms on a surface, but this time with specific ligands, could lead to a more predictive approach in heterogeneous catalysis. The predictive character of SOMCat was just the result of intuitive mechanisms derived from the elementary steps of molecular chemistry. This review article will compare the aspects of single atom catalysis and surface organometallic catalysis by considering several specific catalytic reactions, some of which exist for both fields, whereas others might see mutual overlap in the future. After a definition of both domains, a detailed approach of the methods, mostly modeling and spectroscopy, will be followed by a detailed analysis of catalytic reactions: hydrogenation, dehydrogenation, hydrogenolysis, oxidative dehydrogenation, alkane and cycloalkane metathesis, methane activation, metathetic oxidation, CO2 activation to cyclic carbonates, imine metathesis, and selective catalytic reduction (SCR) reactions. A prospective resulting from present knowledge is showing the emergence of a new discipline from the overlap between the two areas.