Abstract: Pyrolysis is a promising technology for thermal conversion of lignocellulosic biomasses into a higher added value fuel. The aim of this study was to analyze the potential of four agroforestry biomasses to produce energy as a raw material or as a bio-coal. In this study, slow pyrolysis was conducted in three final temperatures to evaluate the bio-coal production of four agroforestry biomasses widely available in Brazil. The biomasses used were sugarcane bagasse (Saccharum sp.), bamboo (Dendrocalamus giganteus), straw bean (Phaseolus vulgaris) and eucalypts wood chips (Eucalyptus sp.). In the first part was presented the raw biomasses proprieties, such as lignin, carbon, hydrogen and ash contents. In the second part was showed the bio-coal proprieties, such as gravimetric and fixed carbon yields, fixed carbon and ash contents. These bio-coal results were showed as a function of final temperature of pyrolysis. The best energy indicators for bio-coal production, such as fixed carbon yield, high heating value, was observed in the bamboo and eucalypts. The bagasse and straw bean biomasses have high concentrations of ash and low lignin content when compared with the other biomasses assessed and are less suitable to produce bio-coal.

RESUMO O Brasil é o maior produtor de carvão vegetal, sendo que Minas Gerais se destaca como o estado com maior produção desse produto. As propriedades da madeira influenciam a qualidade do carvão vegetal, sendo importante conhecê-las, sabendo-se que essas propriedades sofrem variação com a idade da árvore. Sendo assim, este trabalho teve como objetivo determinar as correlações existentes entre idade, as propriedades da madeira e as propriedades do carvão vegetal. Foram avaliados três clones de Eucalyptus sp., em quatro idades, aos 3, 4, 5 e 7 anos, sendo provenientes da Gerdau S/A. De cada árvore foram retirados cinco discos (0%, 25%, 50%, 75%, 100% da altura comercial do tronco), e foram determinadas a relação cerne/alburno, densidade básica, composição química da madeira, poder calorífico superior da madeira e do carvão vegetal, rendimentos gravimétricos, densidade relativa aparente e análise química imediata do carvão vegetal, além dos gases condensáveis e não condensáveis. Foram realizadas correlações entre a idade, propriedades da madeira e do carvão vegetal. Observou-se correlação negativa entre a idade da madeira e o teor de cinzas do carvão vegetal, independentemente do clone avaliados; correlação positiva entre a densidade básica da madeira e a densidade aparente do carvão; correlação positiva entre o teor de lignina da madeira e a densidade aparente do carvão. A relação siringil/guaiacil, que determina a quantidade de cada tipo de lignina presente na madeira, apresentou correlação negativa com o rendimento gravimétrico em carvão vegetal. Dessa forma, pode-se concluir que a idade da árvore influenciou as propriedades da madeira, independente do clone; a idade do material genético não influenciou o rendimento gravimétrico em carvão vegetal; o clone GG 680 apresentou o maior potencial para a produção de carvão, considerando-se somente as propriedades da madeira.

ABSTRACT Brazil is world's greater producer of charcoal, and the Brazilian state Minas Gerais presents the greater production of said product. The wood proprieties influence the charcoal quality, making important to know them, it is known that these proprieties vary according to the age of the tree. With that being said, this research aimed to determine the correlations existing between age, the proprieties of the wood and charcoal proprieties. Three Eucalyptus sp. clones from Gerdau S/A were evaluated, at four ages, 3, 4, 5 and 7. From each tree, five discs were removed (0%, 25%, 50%, 75% and 100% corresponding to the commercial height of the trunk). We determined the core/sapwood relationship, basic density, chemical composition of the wood, the calorific value of the wood and of the charcoal, the gravimetric yields, apparent relative density and charcoal chemical analysis, in addition to the analysis of the condensable and non-condensable gases. Correlations between age, proprieties of the wood and charcoal were performed. It was observed a negative correlation between the age of the wood and charcoal ashes content, regardless the clones evaluated. A positive correlation between the basic density of the wood and the apparent density of the coal and a positive correlation between the lignin of wood content and the coal apparent density were observed, as well. The siringil/guaiacil relation, which determines the quantity of each type of lignin existent on the wood, presented a negative correlation with the gravimetric yields in charcoal. Therefore, it is concluded that the age of the tree influenced the proprieties of the wood, regardless the clone; the age of the genetic material did not influence the gravimetric yield in charcoal; the GG 680 clone presented greater potential to produce charcoal, considering only the proprieties of the wood.