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A titanium (Ti) commercial cathode material and high purity Ar and O2 were used in the cathodic arc physical vapor deposition (arc-PVD) process. The TiOx coating was deposited on the three sets of Raschig rings using decreasing ratios of Ar/O2:440/60, 400/100 and 300/100. The cross sections of the TiOx PVD coating were analyzed using field emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). A homogeneous layer of Ti with small O content was observed, and the data suggest that a thin TiOx oxide film was deposited. For this reason, a thermal treatment was applied to the coating to oxidize it and form the rutile phase of TiO2 in the coating, which was demonstrated by grazing incidence XRD. In addition, the TiOx coatings absorb radiation, which was observed by diffuse reflectance band gap energy measurement. Silver (Ag) was added by the photo-reduction method, using UVC light to activate the TiO2 coating, and the band gap energy was analyzed by diffuse reflectance. The photocatalytic activities of the films were evaluated by degradation of the model dye rhodamine B and in the removal of fecal coliforms using two matrices, water from a secondary treatment effluent, and synthetic water. [ABSTRACT FROM AUTHOR]

The removal of traces of highly unsaturated compounds, such as 1,3-butadiene, from olefin feedstocks via selective hydrogenation is of particular importance because the oligomerization of these impurities produces deactivation and an increased pressure drop across the catalytic beds used in the polymerization processes. The present work focuses on the selective hydrogenation of 1,3-butadiene in the presence of 1-butene using (xCeO2-)Al2O3-supported NiPd catalysts (x = 0, 1, 2, and 3 wt% CeO2) in both liquid and gas conditions. The samples were characterized by XRD, N2 physisorption, Zeta potential, H2-TPR, NH3-TPD, HRTEM and STEM-HAADF. Modifying the catalysts with CeO2 resulted in an increase of 1,3-butadiene conversion, an enhancement of 1-butene selectivity and a decrease of butane production under liquid phase conditions. In contrast, in the gas phase both the Ce-modified and unmodified catalysts behaved similarly: while the fresh catalysts showed similar reactivity to that found in liquid phase conditions, the reacted and thermally pretreated catalysts showed increased reactivity, leading to full hydrogenation up to butane. The improvements observed under liquid phase conditions may be related to modification of the acid strength with increasing CeO2 loading, which would increase the adsorption of 1,3-butadiene and diminish the further hydrogenation of 1-butene. Optimal activity and selectivity were observed for the catalyst with an Ni/Pd atomic ratio of 1, and loadings of 0.5 wt% Pd and 3.0 wt% CeO2. [ABSTRACT FROM AUTHOR]

Copyright of La Revista Latinoamericana de Metalurgia y Materiales, RLMM is the property of Universidad Simon Bolivar, Departmento de Ciencia de los Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of La Revista Latinoamericana de Metalurgia y Materiales, RLMM is the property of Universidad Simon Bolivar, Departmento de Ciencia de los Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The catalytic performance of Al2O3-supported monometallic and bimetallic catalysts in selective hydrogenation of 1,3-butadiene in the presence of 1-butene under liquid phase conditions was studied. Bimetallic catalysts were prepared by the coimpregnation method with the required amounts of the precursors salts [Ni(NO3)2·6H2O and Pd(NH3)4Cl2·H2O] over pellet-form γ-Al2O3 with a constant content of Pd (0.5 wt%) and varying Ni/Pd atomic ratio (0.25, 0.5, 0.75, and 1) obtaining egg-shell profiles of the active components. The catalysts were characterized by X-ray diffraction, temperature-programmed techniques, such as reduction in hydrogen and desorption of ammonia, N2 physisorption, and transmission electron microscopy. The catalytic test showed that the 1,3-butadiene was selectively hydrogenated when bimetallic catalysts were used. The addition of Ni to the Pd-based catalysts suppressed n-butane formation and increased recovery of 1-butene at medium conversion. Therefore, it was observed an improved catalytic performance of the bimetallic catalysts being highest in the case of the 1NiPd/Al2O3. [ABSTRACT FROM AUTHOR]