title: The mechanisms of hydrothermal deconstruction of lignocellulose: new insights from thermal-analytical and complementary studies.
abstract: Differential Scanning Calorimetry, Dynamic Mechanical Thermal Analysis, gravimetric and chemical techniques have been used to study hydrothermal reactions of straw biomass. Exothermic degradation initiates above 195 °C, due to breakdown of the xylose ring from hemicellulose, which may be similar to reactions occurring during the early stage pyrolysis of dry biomass, though activated at lower temperature through water mediation. The temperature and magnitude of the exotherm reduce with increasing acid concentration, suggesting a reduction in activation energy and a change in the balance of reaction pathways. The presence of xylan oligomers in auto-catalytic hydrolysates is believed to be due to a low rate constant rather than a specific reaction mechanism. The loss of the lignin glass transition indicates that the lignin phase is reorganised under high temperature auto-catalytic conditions, but remains partially intact under lower temperature acid-catalytic conditions. This shows that lignin degradation reactions are activated thermally but are not effectively catalysed by aqueous acid.
authors.affiliation: BBSRC Sustainable Bioenergy Centre, University of Nottingham, Sutton Bonington Campus, Loughborough LE125RD, UK. Roger.ibbett@nottingham.ac.uk
authors.forename: Roger
authors.initials: R
authors.lastname: Ibbett
authors.forename: Sanyasi
authors.initials: S
authors.lastname: Gaddipati
authors.forename: Scott
authors.initials: S
authors.lastname: Davies
authors.forename: Sandra
authors.initials: S
authors.lastname: Hill
authors.forename: Greg
authors.initials: G
authors.lastname: Tucker
mesh_terms: D000143:Acids / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002384:Catalysis; D006358:Hot Temperature; D008031:Lignin / Q000032:analysis / Q000737:chemistry*; D008956:Models, Chemical; D018547:Plant Stems / Q000737:chemistry*; D013818:Thermogravimetry; D014990:Xylans / Q000737:chemistry
chemical_list: D000143:Acids; D014990:Xylans; C036909:lignocellulose; D008031:Lignin