O tratamento normalizado do registo arqueológico : uma proposta informática

Este trabalho pretende, por um lado, ensaiar um sistema de informação que permita integrar todo o processo de investigação arqueológica, e por outro, adiantar sugestões e apontar soluções para a recolha da informação no campo, de forma normalizada, prática e eficaz. O desenvolvimento deste trabalho consiste, por isso, na conceptualização de um sistema de informação arqueológica centralizado numa base de dados convergente, a partir da qual serão alimentadas bases de dados móveis. Às bases de dados móveis será fornecida informação parcial, disponibilizada pela base de dados central. Do mesmo modo, será a partir da informação recolhida no campo, armazenada nas bases de dados móveis, que numa fase posterior se alimentará a base de dados central. Este sistema suporta o registo, o armazenamento e a exploração da informação arqueológica e garante a sua correcta ligação à cartografia, de forma a facilitar a posterior interpretação e publicação dos resultados. Paralelamente ao desenvolvimento de um sistema informático que sirva a investigação arqueológica, analisa-se de forma detalhada a informação que deve constar nos formulários para preenchimento no campo, quer durante a prospecção, quer na fase de escavação, pelo que propomos um conjunto de fichas/formulários normalizados, em suporte de papel e digital

Evaluation of nickel and copper catalysts in biogas reforming for hydrogen production in SOFC

The solid oxide fuel cells (SOFC) enable the efficient generation of clean energy, fitting the current requirementsof the growing demand for electricity and for the environment preservation. When powered with biogas(from digesters of municipal wastes), the SOFCs also contribute to reduce the environmental impact ofthese wastes. The most suitable route to produce hydrogen inside SOFC from biogas is through dry reformingbut the catalyst is easily deactivated by coke, because of the high amounts of carbon in the stream. Apromising way to overcome this drawback is by adding a second metal to nickel-based catalysts. Aiming toobtain active, selective and stable catalysts for biogas dry reforming, solids based on nickel (15%) and copper(5%) supported on aluminum and magnesium oxide were studied in this work. Samples were prepared byimpregnating the support with nickel and copper nitrate, followed by calcination at 500, 600 and 800 oC. Itwas noted that all solids were made of nickel oxide, nickel aluminate and magnesium aluminate but no coppercompound was found. The specific surface areas did not changed with calcination temperature but thenickel oxide average particles size increased. The solids reducibility decreased with increasing temperature.All catalysts were active in methane dry reforming, leading to similar conversions but different selectivitiesto hydrogen and different activities in water gas shift reaction (WGSR). This behavior was assigned to differentinteractions between nickel and copper, at different calcination temperatures. All catalysts were active inWGSR, decreasing the hydrogen to carbon monoxide molar ratio and producing water. The catalyst calcinedat 500 oC was the most promising one, leading to the highest hydrogen yield, besides the advantage of beingproduced at the lowest calcination temperature, requiring less energy in its preparation

Preparação de carbonos porosos por moldagem sequencial

Porous carbons have received great attention because of their potential use as adsorbents, sensors, catalytic supports and others. Among the available methods for preparing these solids, the sequential templating emerges as an efficient way to tail carbon materials, with large specific surface areas, high porosity, controlled narrow pore size distribution and different functional groups. The template process is based on the infiltration of carbon precursors into the pores of inorganic frameworks. This work reviews the most important variables involved in the sequential template process to prepare micro, meso and macroporous carbon with tailored properties as well as their applications

Processos avançados de oxidação de compostos fenólicos em efluentes industriais

In an effort to minimize the impact on the environment, removal of pollutants, such as phenolic compounds, from the industrial wastewater has great importance nowadays because of the high toxicity and low biodegradability of these compounds. This work discusses the different methods to remove these compounds from industrial wastewater, showing their advantages and disadvantages. Advanced Oxidation Process (AOPs) are presented as a promising technology for the treatment of wastewater containing phenolic compounds. Among the AOPs, photolysis, photocatalysis and the processes based on hydrogen peroxide and on ozone are discussed with emphasis on the combined processes and the oxidation mechanisms

Suporte Informático para trabalhos de prospecção e escavação arqueológica

Os trabalhos de armazenamento, interpretação e divulgação da informação arqueológica vêem bebendo, há alguns anos, das vantagens do suporte informático, nomeadamente dos Sistemas de Informação Geográfica, das Bases de Dados Relacionais e, em grande medida, da informação vectorizada ou em raster, quer sob a forma de documentação gráfica ou fotográfica. A passagem da informação para o computador, nomeadamente no que respeita à vectorizacão, apresenta-se uma árdua e morosa tarefa, dado o volume e o rigor com que deve ser realizado, sendo necessário recorrer e envolver operadores contratados para o efeito. Esta tarefa fica significativamente condicionada pelas dificuldades de interpretação do registo efectuado no campo por outra pessoa, pelos custos adicionais que implica e pelo atraso entre a recolha dos dados e o seu posterior tratamento e divulgação. Para melhorar o processo de introdução de informação no sistema informático, propomos uma arquitectura para uma solução móvel, que permita que os dados sejam registados em computador, no campo, de forma sistemática e automática, pelos próprios arqueólogos. A arquitectura apresentada define um ciclo que se baseia na preparação de um dispositivo móvel (Palm), em função dos dados que irá recolher, na recolha propriamente dita, e na descarga dos dados para um Sistema de Informação Arqueológica. Para estudar a viabilidade da solução proposta, antes de iniciar o seu desenvolvimento, foram desenvolvidos pequenos protótipos que ensaiam algumas das funcionalidades pretendidas

Effect of iron content on the catalytic properties of activated carbon-supported magnetite derived from biomass

In recent times, the intense human activity has led to an increase of the agriculture wastes in the environment. “In order to find new applications for these materials, the effect of iron content (2.5, 5, 10 and 15%) on the catalytic properties of activated carbon-supported iron oxide, prepared from coconut shells, was studied. The iron amount affected the textural and reducing properties of the solids and particle sizes. Hematite was found for the most iron-poor sample, while particles of magnetite with a core of hematite were found for the others. These catalysts were effective in the methylene blue removal from aqueous solutions by adsorption and Fenton reaction. The solid with 15% of iron was the most active one probably due to the highest iron amount on the surface. These catalysts are environmentally friendly, contributing to the decrease of the solid wastes in the environment as well as to purify textile effluents, preserving water resources.Nos últimos tempos, a intensa atividade humana levou a um aumento de resíduos agrícolas no meio ambiente. Visando a encontrar novas aplicações para estes materiais estudou-se, neste trabalho, o efeito do teor de ferro (2.5, 5, 10 e 15%) sobre as propriedades catalíticas de óxido de ferro suportado em carvão ativado, preparado a partir de cascas de coco. O teor de ferro afetou as propriedades texturais e redutoras dos sólidos. Detectou-se hematita na amostra mais pobre em ferro e magnetita com um núcleo de hematita nas demais. Estes catalisadores foram eficazes na remoção do azul de metileno em soluções aquosas por adsorção e pela reação de Fenton. O sólido com 15% de ferro foi o mais ativo, provavelmente devido à maior quantidade de sítios ativos na superfície. Estes catalisadores são ambientalmente amigáveis, contribuindo para a redução de resíduos sólidos no meio ambiente e purificação de efluentes têxteis, preservando os recursos hídricos.Fil: Lima, Sirlene B.. Universidade Federal da Bahia, Instituto de Química; Brasil. Universidade Estadual de Campinas; BrasilFil: Borges, Sarah Maria. Universidade Estadual de Campinas; Brasil. Instituto de Ciência e Tecnologia de Materiais Complexos Funcionais. Instituto de Química; BrasilFil: Rangel. Maria do Carmo. Universidade Estadual de Campinas; Brasil. Universidade Federal Da Bahia; BrasilFil: Marchetti, Sergio Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Ciencias Aplicadas "dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Ciencias Aplicadas ; Argentin

Effect of iron content on the catalytic properties of activated carbon-supported magnetite derived from biomass

In recent times, the intense human activity has led to an increase of the agriculture wastes in the environment. "In order to find new applications for these materials, the effect of iron content (2.5, 5, 10 and 15%) on the catalytic properties of activated carbon-supported iron oxide, prepared from coconut shells, was studied. The iron amount affected the textural and reducing properties of the solids and particle sizes. Hematite was found for the most iron-poor sample, while particles of magnetite with a core of hematite were found for the others. These catalysts were effective in the methylene blue removal from aqueous solutions by adsorption and Fenton reaction. The solid with 15% of iron was the most active one probably due to the highest iron amount on the surface. These catalysts are environmentally friendly, contributing to the decrease of the solid wastes in the environment as well as to purify textile effluents, preserving water resources.Nos últimos tempos, a intensa atividade humana levou a um aumento de resíduos agrícolas no meio ambiente. Visando a encontrar novas aplicações para estes materiais estudou-se, neste trabalho, o efeito do teor de ferro (2.5, 5, 10 e 15%) sobre as propriedades catalíticas de óxido de ferro suportado em carvão ativado, preparado a partir de cascas de coco. O teor de ferro afetou as propriedades texturais e redutoras dos sólidos. Detectou-se hematita na amostra mais pobre em ferro e magnetita com um núcleo de hematita nas demais. Estes catalisadores foram eficazes na remoção do azul de metileno em soluções aquosas por adsorção e pela reação de Fenton. O sólido com 15% de ferro foi o mais ativo, provavelmente devido à maior quantidade de sítios ativos na superfície. Estes catalisadores são ambientalmente amigáveis, contribuindo para a redução de resíduos sólidos no meio ambiente e purificação de efluentes têxteis, preservando os recursos hídricos.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Ciencias Aplicada

Effect of Dopants on the Properties of Zirconia‐Supported Iron Catalysts for Ethylbenzene Dehydrogenation with Carbon Dioxide

Due to the harmful effects of carbon dioxide to the environment, a lot of work has been carried out aiming to find new applications, which can decrease the emissions or to capture and use it. An attractive application for carbon dioxide is the synthesis of chemicals, especially for producing styrene by ethylbenzene dehydrogenation, in which it increases the catalyst activity and selectivity. In order to find efficient catalysts for the reaction, the effect of cerium, chromium, aluminum, and lanthanum on the properties of zirconia‐supported iron oxides was studied in this work. The modified supports were prepared by precipitation and impregnated with iron nitrate. The obtained catalysts were characterized by thermogravimetry, Fourier transform infrared spectroscopy, X‐ray diffraction, specific surface area measurement, and temperature‐programmed reduction. The catalysts showed different textural and catalytic properties, which were associated to the different phases in the solids, such as monoclinic or tetragonal zirconia, hematite, maghemite, cubic ceria, monoclinic or hexagonal lantana, and rhombohedral chromia, the active phases in ethylbenzene dehydrogenation. The most promising dopant was cerium, which produces the most active catalyst at the lowest temperature, probably due to its ability of providing lattice oxygen, which activates carbon dioxide and increases the reaction rate

A thorium-doped catalyst for the high temperature shift reaction

The reforming of natural gas feedstock in the presence of steam is the main industrial route to produce high purity hydrogen. However, this process also produces carbon oxides which can poison most hydrogenation catalysts as well as ammonia catalysts. In industrial processes, these compounds are often removed from the gaseous stream by the water gas shift reaction (WGSR), which is performed in two steps due to thermodynamics and kinetics considerations. A chromium and copper-doped hematite has been recently proposed as an industrial catalyst in the high temperature shift (HTS). This solid shows a stable performance but the search for non-toxic systems is much needed due to environmental restrictions related to chromium compounds. In this work, the use of thorium instead of chromium in iron- and copper-based catalysts for the HTS reaction was investigated. Catalysts were prepared in the active form (magnetite) in order to save energy, characterized by several techniques and then evaluated in operational conditions close to the industrial ones. It was found that thorium can replace chromium in these catalysts leading to better catalytic properties as compared to chromium. The catalyst has the advantage of being less toxic and can be prepared in the active phase.Centro de Investigación y Desarrollo en Ciencias Aplicada