Comparing thermal-cracking and catalytic hydrocracking in the presence of Rh and Ru catalysts to produce liquid hydrocarbons from vegetable oils

Neste trabalho descrevemos a obtenção de hidrocarbonetos líquidos por meio do hidrocraqueamento catalítico de óleo de soja, dendê e mamona, na presença e ausência de catalisadores nanoparticulados de rutênio e ródio. A reação realizada a 200 ºC leva somente à hidrogenação de ligações duplas C=C. No entanto, a 400 ºC, foi observada a decomposição dos triacilglicerídeos, levando a hidrocarbonetos e compostos oxigenados. O hidrocraqueamento catalítico de óleos vegetais na presença de Rh e Ru levou a um aumento da quantidade de produtos desoxigenados e à formação de hidrocarbonetos lineares de cadeia longa, que são adequados para utilização como combustível para motores diesel, quando comparado com o da reação de pirólise na ausência de catalisadores. O catalisador de Ru é mais eficaz do que o catalisador de Rh, especialmente no caso do óleo de mamona, provavelmente devido à sua maior oxofilicidade quando comparado com Rh.We describe herein the production of liquid hydrocarbons through the catalytic hydrocracking of soybean, palm tree and castor oils, in the presence and absence of ruthenium and rhodium nanoparticle catalysts. The reaction at 200 ºC leads to the hydrogenation of C=C double bonds only. However, at 400 ºC, the decomposition of the triacylglycerides was observed, leading to hydrocarbons and oxygenated compounds. The catalyzed hydrocracking of vegetable oils in the presence of Rh and Ru strongly increased the amount of deoxygenated products and the formation of long-chain linear hydrocarbons, which are suitable for use as diesel fuel, when compared with pyrolysis reaction in the absence of the catalysts. The Ru catalyst is more effective than Rh, especially in the case of castor oil, probably due to its higher oxophilicity when compared to Rh

On the origin of leprosy.

International audienceLeprosy, a chronic human disease with potentially debilitating neurological consequences, results from infection with Mycobacterium leprae. This unculturable pathogen has undergone extensive reductive evolution, with half of its genome now occupied by pseudogenes. Using comparative genomics, we demonstrated that all extant cases of leprosy are attributable to a single clone whose dissemination worldwide can be retraced from analysis of very rare single-nucleotide polymorphisms. The disease seems to have originated in Eastern Africa or the Near East and spread with successive human migrations. Europeans or North Africans introduced leprosy into West Africa and the Americas within the past 500 years

Los docentes de Telebachilleratos Comunitarios, perfiles que orientan la práctica y flexibilización de los procesos formativos

This article presents results of a research that aimed to analyze the profile and work conditions for teachers that belong to the Community Tele-Baccalaureates (TBC) in Guanajuato, Mexico. Specially, in this paper we focused on answering questions related to teachers’ profile and their relationship with the type of teaching taken on, and how their profile and incorporation process determine the results. The CIPP (Context, Input, Process, Product) model was followed for the development of the measurement tools and a qualitative approach was assumed from which interpretive strategies were prioritized. Information obtained through in-depth interviews conducted with CTB teachers from two municipalities in the state of Guanajuato are presented. Among other results, these institutions are characterized as an educational option marked by precariousness. Also, it shows how the profile of teachers guides their practice and the type of work they do in the classroom, impacting the learning processes of students and having the flexibility of such processes as a characteristic.Este artículo presenta resultados de una investigación que tuvo como objetivo analizar el perfil y las condiciones de trabajo de los docentes que integran los Telebachilleratos Comunitarios (TBC) en Guanajuato, México. Particularmente nos concentramos en responder preguntas referentes al perfil de estos y su relación con el tipo de docencia asumida, así como la forma en que ese perfil y el proceso de incorporación al TBC condiciona parte de sus resultados. Se siguió el modelo CIPP (Context, Input, Process, Product) para la construcción de los instrumentos y se asumió un enfoque cualitativo desde el que se priorizaron estrategias interpretativas. Se presenta información obtenida mediante entrevistas a profundidad, realizadas a docentes de los TBC de dos municipios del estado de Guanajuato. Entre otros resultados, se caracteriza a estas instituciones como una opción educativa marcada por la precariedad. También se muestra cómo el perfil de los docentes orienta la práctica de estos y el tipo de trabajo que realizan en el aula, impactando en los procesos formativos de los estudiantes, teniendo como característica la flexibilización de tales procesos

Selective Allylic oxidation of Cyclohexene by a Magnetically Recoverable Cobalt Oxide Catalyst

In this work, we prepared a new magnetically recoverable CoO catalyst through the deposition of the catalytic active metal nanoparticles of 2-3 nm on silica-coated magnetite nanoparticles to facilitate the solid separation from liquid media. The catalyst was fully characterized and presented interesting properties in the oxidation of cyclohexene, as for example, selectivity to the allylic oxidation product. It was also observed that CoO is the most active species when compared to Co(2+), Co(3)O(4) and Fe(3)O(4) in the catalytic conditions studied.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESPCNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)INCT-CataliseINCT-Catalis

Catalyst Recovery and Recycling Facilitated by Magnetic Separation: Iridium and Other Metal Nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The immobilization of metal nanoparticles in magnetic responsive solids allows the easy, fast, and clean separation of catalysts; however, the efficiency of this separation process depends on a strong metalsupport interaction. This interaction can be enhanced by functionalizing the support surface with amino groups. Our catalyst support contains an inner core of magnetite that enables the magnetic separation from liquid systems and an external surface of silica suitable for further modification with organosilanes. We report herein that a magnetically recoverable amino-functionalized support captured iridium species from liquid solutions and produced a highly active hydrogenation catalyst with negligible metal leaching. An analogous Ir0 catalyst prepared with use of a nonfunctionalized support shows a higher degree of metal leaching into the liquid products. The catalytic performance in the hydrogenation of alkenes is compared with that of Rh and Pt catalysts.45698703INCT-CataliseBrazilian government agency FAPESPConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Catalyst Recovery and Recycling Facilitated by Magnetic Separation: Iridium and Other Metal Nanoparticles

The immobilization of metal nanoparticles in magnetic responsive solids allows the easy, fast, and clean separation of catalysts; however, the efficiency of this separation process depends on a strong metalsupport interaction. This interaction can be enhanced by functionalizing the support surface with amino groups. Our catalyst support contains an inner core of magnetite that enables the magnetic separation from liquid systems and an external surface of silica suitable for further modification with organosilanes. We report herein that a magnetically recoverable amino-functionalized support captured iridium species from liquid solutions and produced a highly active hydrogenation catalyst with negligible metal leaching. An analogous Ir0 catalyst prepared with use of a nonfunctionalized support shows a higher degree of metal leaching into the liquid products. The catalytic performance in the hydrogenation of alkenes is compared with that of Rh and Pt catalysts.INCT-CataliseINCTCataliseBrazilian government agency FAPESPBrazilian government agency FAPESPBrazilian government agency CNPqBrazilian government agency CNP

Aerobic oxidation of monoterpenic alcohols catalyzed by ruthenium hydroxide supported on silica-coated magnetic nanoparticles

Ruthenium hydroxide supported on silica-coated magnetic nanoparticles was shown to be an efficient heterogeneous catalyst for the liquid-phase oxidation of a wide range of alcohols using molecular oxygen as a sole oxidant in the absence of co-catalysts or additives. The material was prepared through the loading of the amino modified support with ruthenium(III) ions from an aqueous solution of ruthenium(III) chloride followed by treatment with sodium hydroxide to form ruthenium hydroxide species. Characterizations suggest that ruthenium hydroxide is highly dispersed on the support surface, with no ruthenium containing crystalline phases being detected. Various carbonylic monoterpenoids important for fragrance and pharmaceutical industries can be obtained in good to excellent yields starting from biomass-based monoterpenic alcohols, such as isobomeol, perillyl alcohol, carveol, and citronellol. The catalyst undergoes no metal leaching and can be easily recovered by the application of an external magnet and re-used. (C) 2011 Elsevier Inc. All rights reserved.CNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPESFAPESPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPEMIGFundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)INCT-Catalise (Brazil)INCT-Catalise (Brazil