Applied catalysis a-general

Acesso restrito: Texto completo. p. 50-62.Catalytic performance of binary nanostructured oxides has been evaluated in the gasphase dehydration of glycerol, an environmental friendly reaction. SnO2–Mn2O3, SnO2–ZrO2, SnO2–TiO2, ZrO2–Mn2O3 nanocasted oxides, and a reference, NiO–Co3O4, were characterised by XRD, Raman spectroscopy, acid–base measurements, SEM–EDX, TPR, HTEM and XPS. Correlations among the catalyst’s activity and the surface, textural, and acid–base properties of the nanocasted oxides were tentatively conducted in attempts to justify the catalytic results. Influences of nanoparticle or nanostructure structural properties on the catalytic activity have been investigated. The better activity of SnO2–TiO2 at 250 ◦C and a glycerol/ water molar ratio of 0.25 was due to cooperativity of Sn4+ and Ti4+. The most important finding was that nanostructure features of the solid enhanced nanoparticle stability through the redox ability of the binary solid compared to conventional binary catalysts

Characterizing Complex Mineral Structures in Thin Sections of Geological Samples with a Scanning Hall Effect Microscope

We improved a magnetic scanning microscope for measuring the magnetic properties of minerals in thin sections of geological samples at submillimeter scales. The microscope is comprised of a 200 µm diameter Hall sensor that is located at a distance of 142 µm from the sample; an electromagnet capable of applying up to 500 mT DC magnetic fields to the sample over a 40 mm diameter region; a second Hall sensor arranged in a gradiometric configuration to cancel the background signal applied by the electromagnet and reduce the overall noise in the system; a custom-designed electronics system to bias the sensors and allow adjustments to the background signal cancelation; and a scanning XY stage with micrometer resolution. Our system achieves a spatial resolution of 200 µm with a noise at 6.0 Hz of 300 nTrms/(Hz)1/2 in an unshielded environment. The magnetic moment sensitivity is 1.3 × 10−11 Am2. We successfully measured the representative magnetization of a geological sample using an alternative model that takes the sample geometry into account and identified different micrometric characteristics in the sample slice

Correction: Carmo et al. Effects of the Incorporation of Distinct Cations in Titanate Nanotubes on the Catalytic Activity in NOx Conversion. Materials 2021, 14, 2181

In the original publication, there was a mistake in Figure 1 as published [...

Effects of the Incorporation of Distinct Cations in Titanate Nanotubes on the Catalytic Activity in NOx Conversion

Effects of the incorporation of Cr, Ni, Co, Ag, Al, Ni and Pt cations in titanate nanotubes (NTs) were examined on the NOx conversion. The structural and morphological characterizations evidenced that the ion-exchange reaction of Cr, Co, Ni and Al ions with the NTs produced catalysts with metals included in the interlayer regions of the trititanate NTs whereas an assembly of Ag and Pt nanoparticles were either on the nanotubes surface or inner diameters through an impregnation process. Understanding the role of the different metal cations intercalated or supported on the nanotubes, the optimal selective catalytic reduction of NOx by CO reaction (SCR) conditions was investigated by carrying out variations in the reaction temperature, SO2 and H2O poisoning and long-term stability runs. Pt nanoparticles on the NTs exhibited superior activity compared to the Cr, Co and Al intercalated in the nanotubes and even to the Ag and Ni counterparts. Resistance against SO2 poisoning was low on NiNT due to the trititanate phase transformation into TiO2 and also to sulfur deposits on Ni sites. However, the interaction between Pt2+ from PtOx and Ti4+ in the NTs favored the adsorption of both NOx and CO enhancing the catalytic performance