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The purpose of the present study was to evaluate the ability of LaFeO3 perovskites prepared using the “self-combustion method” to behave as efficient and stable catalysts in phenol oxidation using H2O2 in ambient conditions. Depending on the synthesis conditions, strong differences in the structural, textural and reducibility characteristics of the perovskites, as well as in phenol conversion and TOC abatement level were observed. High TOC abatement (76%) and very low iron leaching (0.27 wt%) were obtained at 40 °C in the presence of LaFeO3 nanoparticles exhibiting the lowest crystal domain size. [ABSTRACT FROM AUTHOR]

Abstract: The selective synthesis of phytosterol esters from natural sterols and methyl esters was investigated on new grounds by a chemical process using basic solids that are reusable, active, and more selective than the currently used homogeneous catalysts (e.g., alkali hydroxides, carbonates). Various lanthanum oxides with different synthesis procedures and varying specific surface areas were tested. The catalytic performance of the new solids and, more specifically, the ability of La2O3 oxides in increasing phytosterol ester selectivity, was correlated with their acido-basic properties, which were fully characterized by infrared spectroscopy. All La2O3 oxides involved surface carbonate species with different structural states and strengths, as revealed by propyne adsorption. The selectivity to phytosterol ester varied from 90 to 96%, confirming that the side reaction of dehydration of β-sitosterol was strongly inhibited. The phytosterol ester yield could reach 89% and was related to the basic strength of the carbonate species. The lower the carbonate basicity, the higher the phytosterol ester yield. Moreover, IR spectra of catalysts diluted in KBr powder showed that the higher the intensity of unidentate carbonate bands, the higher the yield. It was concluded that the synthesis of phytosterol esters from fatty methyl esters and sitosterols in the presence of La2O3 catalysts requires ionic carbonate species of medium basic strength. [Copyright &y& Elsevier]

Abstract: Laser pyrolysis is a promising and versatile method allowing the synthesis of various nanoparticles, with well defined chemical composition, size and structure. This procedure is based on the interaction of a powerful IR laser beam with a mixture of gaseous or liquid precursors, with one of them absorbing the laser radiation. This paper presents the synthesis of nanoPt/TiO2 and nanoPd/TiO2 by laser pyrolysis and preliminary results about their efficiency for elimination of volatile organic compounds (deVOC). The nanoparticles have been synthesized by adding a metallic precursor in a liquid precursor (titanium isopropoxide). X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and IR spectroscopy have been used to analyse their nanostructures and morphologies. The volatile organic compounds elimination (deVOC) tests performed on these nanomaterials demonstrate that Pd-catalysts are very efficient in the total elimination of chloro-compounds. These catalytic properties are unusual, especially because conventional Pd supported catalysts are generally not used for this application due to a production of a high amount of polychlorinated compounds. These results showed that the laser pyrolysis method allows the synthesis of well dispersed titanium-based catalysts not previously reported in the literature. [Copyright &y& Elsevier]