Promising Impregnated Mn-based Oxygen Carriers for Chemical Looping Combustion of Gaseous Fuels

Promising impregnated oxygen carriers, based on copper and iron, have been previously developed for CLC with gaseous fuels (CH4, syngas, LHC). Recently, because of its low cost and environmental compatibility, Mn-based oxygen carriers are now being considered as an attractive option for chemical-looping combustion (CLC) applications. In this work, a screening of different commercial supports in fluidizable particle size for impregnated Mn-based materials has been carried out. Different oxygen carriers have been prepared by incipient impregnation on ZrO2, and CaAl2O4, and evaluated with respect to their mechanical resistance, fuel gas reactivity and fluidization properties such as agglomeration and attrition rate. In a first step, particles showing high enough crushing strength values were selected for the reactivity investigation. The redox reactivity was evaluated through TGA experiments at suitable temperatures for the CLC process (i.e. 850-950 °C) using H2, CO and CH4. Multi cycle redox analysis and full physical and chemical characterization was also performed. In a second step, materials with high enough reactivity were prepared for fluidized bed evaluation. A batch fluidized bed installation with continuous gaseous fuel feed was used to analyze the product gas distribution during reduction and oxidation reactions at different operation temperatures, and agglomeration and attrition behavior of the selected materials. Results showed that an oxygen carrier impregnated using ZrO2 as support, had high enough reactivity and low attrition rate. Therefore, this material can be selected as a candidate for the development of CLC with syngas with promising results

Umidade e congelamento de grãos de amaranto e sua capacidade de expansão térmica

O objetivo deste trabalho foi avaliar a influência do teor de umidade, da temperatura de armazenamento e do momento da hidratação de grãos de amaranto (Amaranthus cruentus L. ) sobre sua capacidade de expansão térmica, bem como comparar as composições químicas de grãos crus e pipocados. Os atributos diâmetro médio ponderado, volume de expansão, densidade, rendimento, quantidade descartada e tempo de residência de grãos da variedade BRS Alegria foram avaliados de acordo com três teores de umidade (9,5, 11,5 e 13,5%), duas formas de armazenamento, temperatura ambiente de ±28ºC e congelado a -18ºC, e dois momentos de hidratação, antes e após congelamento. Utilizou-se chapa metálica aquecida a 215ºC para pipocar os grãos. Grãos congelados com umidade de 13,5% tiveram maior diâmetro médio ponderado e volume de expansão, e menor densidade e tempo de residência. A umidade de 13,5% proporcionou os maiores rendimentos e expansão dos grãos. O armazenamento a -18ºC produziu pipocas maiores e mais leves do que em condições ambientais. As pipocas apresentaram redução nos teores de proteínas e fibras insolúveis e aumento nos de lipídeos e fibras solúveis, em relação ao grão cru. O congelamento dos grãos a -18ºC e sua hidratação a 13,5% de umidade favorecem o pipocamento de grãos de amaranto, com produção de pipocas de melhor qualidade

Microstructural and Colour Analysis of CuCrO<sub>2</sub> Delafossite Obtained by Gelatin Method

In this paper, CuCrO2the compound was synthesized by a route new that uses gelatin as organic precursor in order to application as ceramic pigments. The type of compound delafossite CuCrO2is known for its wide range of application, such as, thermoelectric devices, catalysts for the steam reforming process, ceramic pigments, NiO2 removal, among. The powders resulting from the synthesis process were calcined the 900°C and characterized by X-ray diffraction (XRD), infrared spectroscopy, scanning electron microscopy (SEM), UV-Visible spectroscopy and colorimetry analysis. The results showed for the CuCrO2have coloring green.</jats:p