Sinterização de Ce1-XEuXO2-(X/2) para aplicação como eletrólito sólido em células a combustível de temperaturas intermediárias

Given the environmental concern over global warming that occurs mainly by emission of CO2 from the combustion of petroleum, coal and natural gas research focused on alternative and clean energy generation has been intensified. Among these, the highlight the solid oxide fuel cell intermediate temperature (IT-SOFC). For application as electrolyte of the devices doped based CeO2 with rare earth ions (TR+ 3) have been quite promising because they have good ionic conductivity and operate at relatively low temperatures (500-800 ° C). In this work, studied the Ce1-xEuxO2-δ (x = 0,1, 0,2 and 0,3), solid solutions synthesized by the polymeric precursor method to be used as solid electrolyte. It was also studied the processing steps of these powders (milling, compaction and two step sintering) in order to obtain dense sintered pellets with reduced grain size and homogeneous microstructure. For this, the powders were characterized by thermal analysis, X-ray diffraction, particle size distribution and scanning electrons microscopy, since the sintered samples were characterized by dilatometry, scanning electrons microscopy, density and grain size measurements. By x-ray diffraction, it was verified the formation of the solid solution for all compositions. Crystallites in the nanometric scale were found for both sintering routes but the two step sintering presented significant reduction in the average grain size

Os Estados Unidos da América e a Revolução do Shale

Ao longo dos últimos anos, tem-se verificado grandes mudanças no mercado energético global, sendo os Estados Unidos da América um dos grandes protagonistas. A presente investigação tem como principal objetivo compreender e clarificar o conceito de independência energética/auto-suficiência energética e averiguar a possibilidade e o alcance deste propósito por parte dos Estados Unidos da América, desde a Revolução do Shale. Ao longo desta investigação haverá oportunidade de estudar as políticas energéticas assumidas durante aproximadamente os últimos 40 anos, obter informações sobre a segurança energética dos Estados Unidos, bem como formas de exploração energética americana, política para exportação de energia e impactos geopolíticos. Facilmente se observa ao longo deste trabalho que a auto-suficência não pode ser vista numa perspetiva de criação de condições para o isolacionismo americano mas sim numa perspetiva de instrumentalização e proteção dos seus aliados.

Estudo de massa cerâmica triaxial visando à otimização do ciclo de queima da indústria de cerâmica estrutural

Over recent years the structural ceramics industry in Brazil has found a very favorable market for growth. However, difficulties related to productivity and product quality are partially inhibiting this possible growth. An alternative for trying to solve these problems and, thus, provide the pottery industry the feasibility of full development, is the substitution of firewood used in the burning process by natural gas. In order to contribute to this process of technological innovation, this paper studies the effect of co-use of ceramic phyllite and kaolin waste on the properties of a clay matrix, verifying the possible benefits that these raw materials can give to the final product, as well as the possibility of such materials to reduce the heat load necessary to obtain products with equal or superior quality. The study was divided into two steps: characterization of materials and study of formulations. Two clays, a phyllite and a residue of kaolin were characterized by the following techniques: laser granulometry, plasticity index by Atterberg limits, X-ray fluorescence, X-ray diffraction, mineralogical composition by Rietveld, thermogravimetric and differential thermal analysis. To study the formulations, specifically for evaluation of technological properties of the parts, was performed an experimental model that combined planning involving a mixture of three components (standard mass x phyllite x kaolin waste) and a 23 factorial design with central point associated with thermal processing parameters. The experiment was performed with restricted strip-plot randomization. In total, 13 compositional points were investigated within the following constraints: phyllite ≤ 20% by weight, kaolin waste ≤ 40% by weight, and standard mass ≥ 60% by weight. The thermal parameters were used at the following levels: 750 and 950 °C to the firing temperature, 5 and 15 °C/min at the heating rate, 15 and 45min to the baseline. The results showed that the introduction of phyllite and/or kaolin waste in ceramic body produced a number of benefits in properties of the final product, such as: decreased absorption of water, apparent porosity and linear retraction at burn; besides the increase in apparent specific mass and mechanical properties of parts. The best results were obtained in the compositional points where the sum of the levels of kaolin waste and phyllite was maximal (40% by weight), as well as conditions which were used in firing temperatures of 950 °C. Regarding the prospect of savings in heat energy required to form the desired microstructure, the phyllite and the residue of kaolin, for having small particle sizes and constitutions mineralogical phases with the presence of fluxes, contributed to the optimization of the firing cycle.

Avaliação do potencial energético de cana (Arundo donax L.) no Algarve

Dissertação de Mestrado, Energias Renováveis e Gestão de Energia, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016

Avaliação do efeito de particulados sólidos na eficiência de um inibidor de corrosão recomendado para meios salinos com CO2

The main problem on the exploration activity on petroleum industry is the formation water resulted on the fields producing. The aggravating of this problem is correlated with the advancing technologies used on the petroleum extractions and on its secondary approach objecting the reobtainment of this oil. Among the main contaminants of the water formation are corrosives gases such as: O2, CO2 and H2S, some solids in suspension and dissolved salts. Concerning to those gases the CO2 is the one that produce significant damage for carbon steel on corrosion process of the petroleum and gas industries. Corrosion inhibitors for carbon steel in formation water is one of the most used agents in control of those damages. In this context, the poor investigations of carbon steel corrosion proceeding from solids in suspension is an opened field for studies. On this work the inhibitor effect of the commercial CORRTREAT 703 was evaluated on some specific solids in suspension at saline medium containing 10.000 ppm of de-aerated chloride using CO2 until non oxygen atmosphere been present. For that, quartz, calcium carbonate, magnetite and iron sulphide were subjected to this investigation as the selected solids. The effect of this inhibitor on corrosion process correlated with those specific solids, was measured using electrochemical (resistance of linear polarization and galvanic pair) and gravimetrical techniques. During all the experimental work important parameters were monitored such as: pH, dissolved oxygen, temperature, instantaneous corrosion rate and galvanic current. According to the obtained results it was proved that the suspension solids calcium carbonate and iron sulphide decrease the corrosion process in higher pH medium. Meanwhile the quartz and magnetite been hardness increase corrosion by broking of the passive layer for erosion. In the other hand, the tested inhibitor in concentration of 50 ppm, showed to be effective (91%) in this corrosion process

Efeito da velocidade de aquecimento nas propriedades de produtos da cerâmica estrutural

Heating rate is one of the main variables that determine a fire cycle. In industrial processes that use high temperatures, greater fire great can reduce the cost of production and increase productivity. The use of faster and more efficient fire cycles has been little investigated by the structural ceramic industry in Brazil. However, one of the possibilities that aims at modernizing the sector is the use of roller kilns and the inclusion of natural gas as fuel. Thus, the purpose of this study is to investigate the effect of heating rate on the technological properties of structural ceramic products. Clay raw materials from the main ceramic industries in the state of Rio Grande do Norte were characterized. Some of the raw materials characterized were formulated to obtain the best physical and mechanical properties. Next, raw materials and formulations were selected to study the influence of heating rate on the final properties of the ceramic materials. The samples were shaped by pressing and extrusion and submitted to rates of 1 °C/min, 10 °C/min and 20 °C/min, with final temperatures of 850 °C, 950 °C and 1050 °C. Discontinuous cycles with rates of 10 °C/min or 15 °C/min up to 600 °C and a rate of 20 °C/min up to final temperature were also investigated. Technological properties were determined for all the samples and microstructural analysis was carried out under a number of fire conditions. Results indicate that faster and more efficient fire cycles than those currently in practice could be used, limiting only some clay doughs to certain fire conditions. The best results were obtained for the samples submitted to slow cycles up to 600 °C and fast fire sinterization up to 950 °C. This paper presents for the first time the use of a fast fire rate for raw materials and clay formulations and seeks to determine ideal dough and processing conditions for using shorter fire times, thus enabling the use of roller kilns and natural gas in structural ceramic industries

Estudo de Matérias-Primas do Rio Grande do Norte para Uso em Revestimento Poroso: Influência do teor de dolomita e temperatura de calcinação nas propriedades físico-mecânicas

The state of Rio Grande do Norte presents a great potentiality for the production of ceramic tiles because of having natural raw material in quantity and quality making its economical exploration possible, beyond the great energetic differential of the state, the natural gás. This works aims to study the influence of the dolomite and granulometry concentration and calcinations temperature in the obtaining of formulations for porous coverings which have to be coherent to the project,s specifications. The experiments have involved the physical-chemical and mineralogical characterizations of raw materials and mechanical tests in the dry and burnt proof bodies preceding a mixture experiment planning with the use of the response surface methodology, in order to get the best raw materials combinations to produce a ceramic mass with specific properties. The twelve ceramic masses studied in this work were prepared by the via dry process, characterized, shaped by uniaxial pressing and sinterized in the temperatures of 940ºC, 1000ºC, 1060ºC, 1120ºC and 1180ºC, using a fast burning cycle. The crystalline phases formed during the sintering in the temperatures in study have revealed the presence of anorthite and diopside beyond quartz with a remaining phase. These phases were the main responsible ones by the physical- mechanical properties of the sinterized proof bodies. The proof bodies after the sintering stage have presented water absorption higher than 10% and a good dimensional stability in all studied temperatures. However, the flexural breaking strength results in the temperatures of 940ºC, 1000ºC and 1060ºC, under the temperature zone of the vitrification of ceramic whiteware do not reach the flexural breaking strength specific for the porous wall tile (15 MPa), but in the temperature of 1120ºC next to the vitrification temperature zone, some whiteware ceramic (formulations) has reached the specified value for the porous wall tile. The results of this work have showed that the studied raw materials have great importance for used in the production of porous wall tiles (BIII)

Estudo de adsorvente obtido de terras diatomáceas para remoção de metais pesados em águas produzidas: processamento, caracterização e dinâmica em leito fixo

The acceleration of industrial growth in recent decades on all continents aroused the interest of the companies to counter the impacts produced on the environment, spurred primarily by major disasters in the petroleum industry. In this context, the water produced is responsible for the largest volume of effluent from the production and extraction of oil and natural gas. This effluent has in its composition some critical components such as inorganic salts, heavy metals (Fe, Cu, Zn, Pb, Cd, ), presence of oil and chemicals added in the various production processes. In response to impact, have been triggered by research alternative adsorbent materials for water treatment and water produced, in order to removing oils and acids and heavy metals. Many surveys of diatomaceous earth (diatomite) in Brazil involve studies on the physico-chemical, mineral deposits, extraction, processing and applications. The official estimated Jazi are around 2.5 million tonnes, the main located in the states of Bahia (44%) and Rio Grande do Norte (37,4%). Moreover, these two states appear as large offshore producers, earning a prominent role in research of adsorbents such as diatomite for treatment of water produced. Its main applications are as an agent of filtration, adsorption of oils and greases, industrial load and thermal insulator. The objective of this work was the processing and characterization of diatomite diatomaceous earth obtained from the municipality of Macaíba-RN (known locally as tabatinga) as a low cost regenerative adsorbent for removal of heavy metals in the application of water produced treatment. In this work we adopted a methodology for batch processing, practiced by small businesses located in producing regions of Brazil. The characterization was made by X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area (BET). Research conducted showed that the improvement process used was effective for small volume production of diatomite concentrated. The diatomite obtained was treated by calcination at temperature of 900 oC for 2 hours, with and without fluxing Na2CO3 (4%), according to optimal results in the literature. Column adsorption experiments were conducted to percolation of the in nature, calcined and calcined fluxing diatomites. Effluent was used as a saline solution containing ions of Cu, Zn, Na, Ca and Mg simulating the composition of produced waters in the state of Rio Grande do Norte, Brazil. The breakthrough curves for simultaneous removal of copper ions and zinc as a result, 84.3% for calcined diatomite and diatomite with 97.3 % for fluxing. The calcined fluxing diatomite was more efficient permeability through the bed and removal of copper and zinc ions. The fresh diatomite had trouble with the permeability through the bed under the conditions tested, compared with the other obtained diatomite. The results are presented as promising for application in the petroleum industry

Análise das emissões gasosas de um veículo flex funcionando com diferentes combustíveis

Efforts in research and development of new technologies to reduce emission levels of pollutant gases in the atmosphere has intensified in the last decades. In this context, it can be highlighted the modern systems of electronic engine management, new automotive catalysts and the use of renewable fuels which contributes to reduce the environmental impact. The purpose of this study was a comparative analysis of gas emissions from a automotive vehicle, operating with different fuels: natural gas, AEHC or gasoline. To execute the experimental tests, a flex vehicle was installed on a chassis dynamometer equipped with a gas analyzer and other complementary accessories according to the standard guidelines of emission and security procedures. Tests were performed according to NBR 6601 and NBR 7024, which define the urban and road driving cycle, respectively. Besides the analysis of exhaust gases in the discharge tube, before and after the catalyst, using the suction probe of the gas analyzer to simulate the vehicle in urban and road traffic, were performed tests of fuel characterization. Final results were conclusive in indicating leaded gasoline as the fuel which most contributed with pollutant emissions in atmosphere and the usual gasoline being the fuel which less contributed with pollutant emissions in atmosphere

Avaliação da corrosão em dutos por técnica gravimétrica e de resistência elétrica

With the increasing of demand for natural gas and the consequent growth of the pipeline networks, besides the importance of transport and transfer of oil products by pipeline, and when it comes to product quality and integrity of the pipeline there is an important role regarding to the monitoring internal corrosion of the pipe. This study aims to assess corrosion in three pipeline that operate with different products, using gravimetric techniques and electrical resistance. Chemical analysis of residues originated in the pipeline helps to identify the mechanism corrosive process. The internal monitoring of the corrosion in the pipelines was carried out between 2009 and 2010 using coupon weight loss and electrical resistance probe. Physico-chemical techniques of diffraction and fluorescence X-rays were used to characterize the products of corrosion of the pipelines. The corrosion rate by weight loss was analyzed for every pipeline, only those ones that has revealed corrosive attack were analyzed located corrosion rate. The corrosion potential was classified as low to pipeline gas and ranged from low to severe for oil pipelines and the pipeline derivatives. Corrosion products were identified as iron carbonate, iron oxide and iron sulfide

Roteiro Tecnológico (roadmap) da Captação, Utilização e Armazenamento de Dióxido de Carbono (CCUS) em Portugal

O objetivo primordial deste trabalho foi estabelecer um roteiro tecnológico para aplicação das tecnologias de “Captação, Utilização e Sequestração de Carbono - CCUS” em Portugal. Para o efeito procedeu-se à identificação da origem das maiores fontes emissoras estacionárias industriais de CO2, adotando como critério o valor mínimo de 1×105 ton CO2/ano e limitado apenas ao território continental. Com base na informação recolhida e referente aos dados oficiais mais recentes (ano de 2013), estimou-se que o volume de emissões industriais de CO2 possível de captar em Portugal, corresponde a cerca de 47 % do valor global das emissões industriais, sendo oriundo de três setores de atividade industrial: produção de cimento, de pasta de papel e centrais termoelétricas a carvão. A maioria das grandes fontes emissoras industriais localiza-se no litoral do país, concentrando-se entre Aveiro e Sines. Pelas condicionantes geográficas do país e, sobretudo pela vantagem de já existir uma rede de gasodutos para o transporte de gás natural, com as respetivas infraestruturas de apoio associadas, admitiu-se que o cenário mais favorável para o transporte do CO2 captado será a criação de um sistema de transporte por gasoduto específico para o CO2. Como critério de compatibilização da proximidade das fontes emissoras de CO2 com potenciais locais para o armazenamento geológico das correntes captadas, adotou-se a distância máxima de 100 km, considerada adequada perante a dimensão do território nacional e as características do tecido industrial nacional. Efetuou-se a revisão das tecnologias de captação de CO2 disponíveis, quer comercialmente, quer em níveis avançados de demonstração e procedeu-se à análise exploratória da adequação desses diferentes métodos de captação a cada um dos setores de atividade industrial previamente identificados com emissões de CO2 suscetíveis de serem captadas. Na perspetiva da melhor integração dos processos, esta análise preliminar tomou em consideração as características das misturas gasosas, assim como o contexto industrial correspondente e o processo produtivo que lhe dá origem. As possibilidades de utilização industrial do CO2 sujeito à captação no país foram tratadas neste trabalho de forma genérica dado que a identificação de oportunidades reais para a utilização de correntes de CO2 captadas exige uma análise de compatibilização das necessidades efetivas de utilização de CO2 por parte de potenciais utilizadores industriais que carece da caracterização prévia das propriedades dessas correntes. Este é um tipo de análise muito específico que pressupõe o interesse mútuo de diferentes intervenientes: agentes emissores de CO2, operadores de transporte e, principalmente, potenciais utilizadores de CO2 como: matéria-prima para a síntese de compostos, solvente de extração supercrítica na indústria alimentar ou farmacêutica, agente corretor de pH em tratamento de efluentes, biofixação por fotossíntese, ou outra das aplicações possíveis identificadas para o CO2 captado. A última etapa deste estudo consistiu na avaliação das possibilidades de armazenamento geológico do CO2 captado e envolveu a identificação, nas bacias sedimentares nacionais, de formações geológicas com características reconhecidas como sendo boas indicações para o armazenamento de CO2 de forma permanente e em segurança. Seguiu-se a metodologia preconizada por organizações internacionais aplicando à situação nacional, critérios de seleção e de segurança que se encontram reconhecidamente definidos. A adequação para o armazenamento de CO2 das formações geológicas pré-selecionadas terá que ser comprovada por estudos adicionais que complementem os dados já existentes sobre as características geológicas destas formações e, mais importante ainda, por testes laboratoriais e ensaios de injeção de CO2 que possam fornecer informação concreta para estimar a capacidade de sequestração e de retenção de CO2 nestas formações e estabelecer os modelos geológicos armazenamento que permitam identificar e estimar, de forma concreta e objetiva, os riscos associados à injeção e armazenamento de CO2.

Formulação de betão autocompactável com resíduos de pedreiras do Alentejo: Aproveitamento de resíduos no fabrico do betão

Os betões autocompactáveis (BAC) são betões que se definem pela capacidade de fluir no interior das cofragens, preenchendo-as e envolvendo as armaduras só por acção do seu próprio peso, sem bloqueio dos agregados e mantendo-se homogéneo em todo o seu volume. As adições activas do tipo II nomeadamente as cinzas volantes, utilizadas na fabricação do BAC irão escassear no futuro pelo facto de provirem da queima do carvão da qual resulta uma quantidade elevada de C02. Para minimizar estas emissões, o carvão começa a ser substituído por gás natural. Mas, como o BAC necessita duma grande quantidade de finos, há necessidade de encontrar outros subprodutos que a substituam. Tendo em conta o que atrás se afirma introduziram-se na fabricação do BAC resíduos de pedreira do Alentejo, identificaram-se as suas características no estado fresco e no estado endurecido. Este estudo teve também em conta o factor económico da sua produção. /ABSTRACT: Self-Compacting (SCC) is concrete which may be defined by the ability to flow inside the formwork, filling them and involving the reinforcements only by action of its own weight, without blocking and maintaining uniformity throughout its volume. Type II additions, as fly ash, are used in the manufacture of SCC. The supply of fly ash in the future will be difficult because they come from the burning of coal resulting in a high amount of C02. To minimize these emissions, coal is being replaced by natural gas. But, as the BAC requires a large amount of fine materials, the formulation of SCC requires other fine products. Having this in mind, the use of waste from Alentejo quarries in concrete was tested. The characteristics of SCC with waste material were identified in fresh and hardened state. This study also took into account the economic factor of production.

Synthetic studies in aromatic hemiterpenes of natural origin, Part 5: Synthesis of 6-acetyl-2,2-dimethyl-8-methoxychromene via benzylic oxidation route

The synthesis of 6-acetyl-2,2-dimethyl-8-methoxychromene (lc), a naturally occurring isomer of encecalin (la)h~s been described startilag from 2,2,6- trimethyl-8-methoxyclaromene (2e) which was obtained from creosol (4) in two steps involving condensation of the phenol with malic acid to the coumarin (3), followed by Grignard reaction with CHaMgI. The transformation of (2e) to the natural product (lc) was effeeted by oxidative dehydrogenation by DDQ of the 6-meth~r function to the formyl group (2f), Grignard reaction to the carbinol (2g) and finally its oxidation to the acetyl moiety (lc), the sequence of the essential steps schematically summarised as : Ar-CHs --* Ar-CHO --* Ar-CH (OH) CHs --* Ar---COCHs.