National Nuclear Energy Commission

About: National Nuclear Energy Commission is a government organization based out in Rio de Janeiro, Brazil. It is known for research contribution in the topics: Dosimetry & Laser. The organization has 3816 authors who have published 4694 publications receiving 59951 citations.

Solvent-free liquid-phase autoxidation of monoterpenes catalyzed by sol–gel Co/SiO2

Abstract: Oxidation of limonene, 3-carene, α-pinene and β-pinene with dioxygen promoted by heterogeneous sol–gel Co/SiO2 catalysts has been performed under solvent-free conditions. Limonene and α-pinene give both epoxidation and allylic oxidation products, with chemoselectivities for the latter being 50–60% at a 40% substrate conversion. On the other hand, oxidation of β-pinene leads essentially to allylic products, i.e., highly valuable pinocarveol, pinocarvone, myrtenol and myrtenal. Good combined selectivities of up to 88% at ca. 40% conversion have been achieved. The activity of the Co/SiO2 catalysts is strongly influenced by the temperature of their thermal treatment. No cobalt leaching occurs under the reaction conditions and the catalysts can be recovered and reused several times.

Production of Biochar, Bio-Oil and Synthesis Gas from Cashew Nut Shell by Slow Pyrolysis

Abstract: Cashew nut shell waste from northeast region of Brazil was characterized and slow pyrolyzed in a simple batch type reactor heated externally by liquefied petroleum gas as fuel. The experiments were performed using nitrogen or air as carrier gases. The properties of biochar, bio-oil and gases products were investigated and potential applications were proposed. Cashew nut shell showed a high heating value of 20.7 MJ kg−1 that is among the highest found for different types of biomass. Pyrolysis under nitrogen flow showed a yield of solid, liquid and gas products of about 30, 40 and 30 wt%, respectively. Under air flow an increase of gas phase (46 wt%) was observed with a decrease in the production of biochar and, mainly bio-oil. The biochars have high contents of carbon (70–75 wt%) and high heating values in the range of 25–28 MJ kg−1 presenting suitable properties for use as energy source. Biochars also contain significant quantities of K and minor amounts of Mg, Ca, Cu, Zn and Fe showing potential as fertilizer. The bio-oils showed high heating values of about 32 MJ kg−1 and are not suitable for use in pure form, but can be used in mixtures with Diesel (42.5 MJ kg−1). The gas phase revealed the predominance of CO2 and CO at temperatures lower than 400 °C and, above this temperature, there was a preferential formation of H2 resulting in synthesis gas with different compositions that could be burned to supply heat for the pyrolysis process and/or to produce organic chemicals.