Autohydrolysis Pretreatment of Mixed Softwood to Produce Value Prior to Combustion
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Autohydrolysis Pretreatment of Mixed Softwood to Produce Value Prior to Combustion Yan Pu & Trevor Treasure & Ronalds Gonzalez & Richard A. Venditti & Hasan Jameel
Published online: 21 June 2013 # Springer Science+Business Media New York 2013
Abstract Autohydrolysis is a hot water pretreatment to extract soluble components from wood that can be used prior to converting the woody residuals into paper, wood products, fuel, or other goods. In this study, mixed softwood chips were autohydrolyzed in hot water at 150, 160, 170, and 180 °C for 1 and 2 h residence times. The objective was to understand the tradeoff between the extraction of fermentable sugar and the residual solid total energy of combustion quantitatively. This process strategy will be referred to as “value prior to combustion”. High-performance liquid chromatography was used to determine chemical compositions (sugars and byproducts such as acetic acid, furfural, and hydroxymethylfurfural) of the extracted liquid and residuals; a bomb calorimeter was used to measure the heating value of original wood and solid residue. As the autohydrolysis temperature increased, material balances of the system indicated higher volatile byproducts loss. More hemicelluloses were solubilized by the hot water extraction process at higher temperatures and longer residence times, and a greater degree of sugar degradation was also observed. The maximum sugar yield was determined to occur at conditions of 170 °C for 2 h, during which 13 g of sugar was recovered from the extract out of 100 g of oven-dried wood. The heating value of the solid residues after extraction was greater than the original wood. The total energy content of the solid residual after extraction ranged from 85 to 98 % of the original energy content of the feed with higher temperatures reducing the total energy content. Keywords Autohydrolysis . Softwood . Carbohydrate . Value prior to combustion . Hemicellulose . Heating value
Y. Pu : T. Treasure : R. Gonzalez : R. A. Venditti (*) : H. Jameel Department of Forest Biomaterials, College of Natural Resources, North Carolina State University, 1204 Biltmore Hall, Raleigh, NC 27695-8005, USA e-mail: [email protected]
Introduction Lignocellulosic materials have been recognized as one of the most promising candidate feedstocks for biofuels due to their availability in nature, low cost, and positive environmental attributes [1–3]. Woody materials and/or wastes have already been widely used either in the pulping industry or for power generation [4]. There is tremendous interest to study their value-added chemical byproducts potential [3, 5]. Lignocellulosic feedstocks are basically composed of three components: cellulose, hemicelluloses, and lignin [6, 7]. Cellulose is a linear homopolymer (one-dimensional polymer) composed of D-glucose units connected by a β(1,4) linkage. Its chemical composition, structure, and crystallinity provide the biomass with insolubility in liquids and strength. Hemicelluloses are heteropolymers built up with five and six carbon sugar
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