Surplus of glycerol production from the biodiesel industry has led to the search for glycerol conversion routes, the most common of which are dehydration and oxidative dehydration. Vanadium and molybdenum oxides were supported on γ-Al 2 O 3 and their properties were analyzed through several characterization techniques, showing that the acidity increases after addition of oxides and that in the catalyst with vanadium and molybdenum there is decrease in the band referring to V 5+ , responsible for sequential oxidation to CO 2 . The effect of the metal oxides on catalytic activity and stability during oxidative dehydration of glycerol to acrolein was investigated and correlated with chemical composition, acidity, and textural properties. Moreover, the global reaction, turnover frequency (TOF), and activation energy were determined. Catalyst performance and stability were found to depend on acidity and the supported metal with larger residence times (W/F) favored acrolein formation over CO x . In addition, metal oxides decreased catalyst deactivation via coke oxidation.

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Because of increases in the burning of fossil fuels, there is an increased emission of pollutant gases (e.g. CO 2 ) into the atmosphere. An alternative to minimize these emissions is to capture these gases using porous materials, such as layered double hydroxides (LDHs). In this study, LDHs were synthesized by co-precipitation of ion salts of Mg 2+ and Al 3+. After the synthesis, the materials were treated with a template to expand the layers. The samples were then characterized by X-ray diffraction, thermogravimetric analysis/derivative thermogravimetry, adsorption/desorption of nitrogen, scanning electron microscopy/energy-dispersive X-ray spectroscopy and transmission electron microscopy. A CO 2 adsorption study was then performed to determine the adsorption capacity of the material in accordance with the contact time between the gas and the adsorbent. The adsorption capacities of LDHs and LDHs-P123 for CO 2 were 0.72 and 1.36 mmol/g, respectively, showing satisfactory results post-treatment.

Recebido em 25/05/2017; aceito em 24/10/2017; publicado na web em 04/12/2017 ADSORPTION OF BIODIESEL CONTAMINANTS BY SURFACE-MODIFIED BAGASSE FIBERS. Sugarcane bagasse fibers chemically modified on its surface were used to adsorb contaminants from biodiesel. Two biodiesel samples were used as adsorbates: crude and washed biodiesel. The contaminants were mainly glycerol and water, but also ions, and methanol. The biodiesel is usually washed, in order to remove most of the contaminants, but the procedure introduces large amounts of water, which are further difficult to remove, because the biodiesel acting as an acceptor of hydrogen bond. The adsorbent used in this work was proved to be very efficient to remove the contaminants and also to remove water from the washing the crude biodiesel. The contaminants adsorbed from biodiesel were identified by thermal analyses (DSC and DTA) of the fibers (adsorbent) and of the biodiesel (adsorbate) by comparing the results with the pure biodiesel. The proportion of free glycerol showed high adsorption efficiency for the crude biodiesel. A total amount of 1.34 g of fibers was estimated as being needed for its complete removal. The mass of bagasse fibers added (up to 1g) in a fixed volume of biodiesel was a relevant condition, as the saturation in fibers started at around 0.70 g cleaning up to about 98% removal of the impurities.Keywords: adsorption; bagasse; biodiesel; contaminants. INTRODUÇÃOO suprimento de energia ainda é majoritariamente dependente dos combustíveis fósseis: petróleo, carvão e gás natural. Considerando que as fontes fósseis são finitas, os gases da exaustão, produtos da combustão, são fortemente prejudiciais à sustentabilidade ambiental e os combustíveis têm o preço afetado por conflitos devido a instabilidades políticas, nas áreas de grande produção, são motivos que estimulam mais a ampliação da busca por fontes alternativas de energia e combustíveis renováveis. No cenário de inovação do mercado energético mundial, o Brasil tem destaque devido ao seu potencial de produção de biocombustíveis, tanto para suprir sua demanda interna quanto para exportar. 1 A grande extensão territorial do Brasil (é o quinto país de maior extensão de área territorial do globo) e a sua localização geoclimá-tica, situado em sua maior parte na zona tropical, favorece produção de biomassas diversificadas, sendo praticamente toda sua extensão aproveitável para a exploração agropecuária.2 Assim sendo, é viável a destinação de espaços para a cultura de vegetais oleaginosos, visando à produção de biocombustíveis.Biocombustíveis são substâncias derivadas de biomassa em base renovável, podendo substituir parcial ou totalmente os combustíveis fósseis. São empregados diretamente ou com poucas alterações, em motores a combustão interna ou, também, para outros tipos de geração de energia. Assim como o etanol, o biodiesel tem significativas vantagens ambientais. Estudos do National Biodiesel Board 7 (associação que representa a indústria de biodiesel nos Estados Unidos) demonstraram que a queim...

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