The research focused on the hydrothermal synthesis of a material based on a Kesterite structure of Cu2ZnSnS4 (CZTS). For this purpose, the component cations, in concentrations of 1.0 molL-1, were placed in a steel autoclave under different temperatures conditions (200, 220, 240, 260 and 280°C) for 32 h. After, the solids were calcined at 400°C for 2 h. UV-VIS results showed that materials had a strong tendency to absorb in the region of 600-800 nm, with band-gap around 1.54 eV. XRD and Raman confirmed a structure with tetragonal geometry, preferably oriented along the (112) facet, as well as low frequency vibrational and rotational modes typical of CZTS. TEM showed nanometric crystallites (≈41.6 ����). XPS showed the Cu2+, Sn4+, Zn2+ and S4- species in correspondence with its main oxidation states. The electrical analysis, allowed to evaluate the behavior under load conditions, suggesting a potential use these materials for photovoltaic applications.

Effects of K addition on the performance of supported Fe catalysts for Fischer - Tropsch synthesis (FTS) were studied in a slurry reactor at 240 to 270ºC, 2.0 to 4.0 MPa and syngas H2/CO = 1.0. The catalysts were characterized by N2 adsorption, H2 temperature programmed reduction, X - ray diffraction, X - ray fluorescence, thermogravimetric analysis, scanning electron microscopy and dispersive X - ray spectroscopy. A strong interaction was observed between Fe and K, which inhibited the reduction of Fe catalyst. Addition of potassium increased the production of heavy hydrocarbons (C20+).

The oxidation of propane on was studied with Pt-xWO3/Al2O3 catalysts was studied ,by varying the concentration of tungsten sublayer. Thermal analysis and XRD in situ showed that the enrichment of tungsten at the surface is associated with the formation of HxWO3 bronze. FTIR results with C3H8 and O2 indicated that the catalyst surface properties and the interaction between W and Pt were modified. These modified surface complexes prevented the formation of acetates and formate species. The addition of W increased the activity of Pt/Al2O3 towards in C3H8 oxidation. Tungsten was the main responsible for the stability of the bimetallic catalysts in the presence of water.

The use of the ion-exchange method and the addition of lithium to Pt/Nb2O5 catalysts were investigated in this work, using techniques of temperature-programmed reduction, H2 and CO chemisorption, UV-Vis diffuse reflectance spectroscopy and the conversion of n-heptane as a catalytic test. The superficial precursor present after the calcination step is platinum oxide, as previously observed for Pt/Nb2O5 catalysts prepared by the incipient wetness method. For some of the samples, autoreduction was observed during the calcination step, with the formation of low dispersion metallic platinum. The Pt/Nb2O5 catalysts prepared by ion exchange showed a high yield of olefins, as compared to aromatics, in the conversion of n-heptane. However, a high yield of hydrogenolysis products was also observed. For some of the lithium-containing samples, there was a suppression of dehydrogenation and aromatization reactions, with an increase in central C-C bond hydrogenolysis.