Agrosilvopastoral waste, regarding agriculture and agro-industry sectors, is pointed as a promising sustainable raw material for biofuels production, specially concerning exploitation of lignocellulosic organic residues for fermentable sugars and cellulosic ethanol output, being therefore necessary to investigate the potential of these substrates concerning chemical composition, since many of them were not reported yet in literature. Being so, this paper presents a study of chemical composition and enzymatic hydrolysis of wastes from the four main crops in Maranhão, Brazil (soy, cassava, rice and corn) which are usually underutilized or abandoned in the field. The results of enzymatic hydrolysis were satisfactory for both soy and particularly corn residues, which presented total reducing sugars (TRS) percentage greater than 50% in comparison with pure cellulose.

The aim of the present study is to assess the potential of ethanol deriving from the mesocarp of babassu coconut to be used in fuel cells. Babassu ethanol was generated through hydrolysis and fermentation processes. The Pt, PtRh and PtRu electrodes were prepared in carbon Vulcan XC72R through the reduction method and applied as electrocatalysts in ethanol oxidation reaction. X-Ray diffraction (XRD), energy-dispersive X-ray (EDX), stripping CO, cyclic voltammetry, chronoamperometry, and online differential electrochemical mass spectrometry (DEMS) were used to characterize the synthesized eletrocatalysts. The electrocatalyst Pt80Ru20/C presented larger active area and higher catalytic activity than other studied materials. The current efficiency of CO2 production rated less than 1% in all studied electrocatalysts, thus showing that babassu ethanol oxidation produces less pollutants than the commercial ethanol.

Neste trabalho é apresentada a reação de condensação aldólica entre metanol e acetona promovida por nanopartículas de dióxido de estanho, não dopadas e dopadas com as terras raras Ce e Y. Diversas condições de relação molar metanol/acetona foram avaliadas, objetivando a obtenção com elevada seletividade do composto a, b-insaturado, metil vinil cetona. As nanopartículas foram preparadas empregando-se o método dos precursores poliméricos. As amostras foram caracterizadas por meio de adsorção de N2 para determinação de área superficial específica (BET), difração de raios X (DRX), adsorção química de CO2, espectroscopia de fotoelétrons (XPS) e microscopia eletrônica de transmissão (MET). O comportamento catalítico observado para as amostras de SnO2 sugere que a relação molar metanol/acetona e a dopagem com as terras raras desempenham um papel importante na atividade catalítica do material e na seletividade aos produtos reacionais. Os resultados de DRX e XPS apontam para a formação de uma camada de segregação, para as amostras dopadas, devido ao tratamento térmico imposto. Essa camada de segregação afeta diretamente o comportamento catalítico do material frente à reação de condensação.

Aldol condensation between methanol and acetone, catalyzed by undoped and rare earths (Ce and Y) doped tin oxide nanoparticles is presented. Several methanol/acetone molar ratio conditions were evaluated aiming to produce methyl vinyl ketone as the main product. The undoped and doped ultrafine nanoparticles of tin oxide were prepared using the polymeric precursor method. The characterization was carried out by means of N2 adsorption (BET), X-ray diffraction (XRD), CO2 chemisorption, X-ray photoemission spectroscopy (XPS) and transmission electron microscopy (TEM). The catalytic behavior observed for SnO2 samples suggests that the methanol/acetone molar ratio and Ce and Y doping play an important role in the catalytic activity and in the product selectivity. The results from XRD and XPS pointed to the de-mixing process for the doped samples, due to the heat-treatment. This segregation layer contributes to the observed change in the catalytic behavior.

The objectives of this work are to supply a basic background on nanostructured materials and also to report about the obtaining of nanoparticles, mainly, tin dioxide nanocrystalline particles (obtained by using the polymeric precursor method) presenting a high stability against particle growth due to the usage of a metastable solid solution. The synthesis and growth of SnO2 nanoribbons by a carbothermal reduction process are also discussed.