1-6-anhydro-beta-glucopyranose and sulfuric-acid

In this work, a Japanese cedar wood sample was treated during the first step at ambient temperature and atmospheric pressure using several concentrations of sulfuric acid (H2SO4) in a stirred flask. During this pretreatment C-O bonds of cellulose, hemicellulose, and lignin were cleaved. The second step involved the pyrolysis of the pretreated wood sample at 550 °C in a quartz glass tube reactor. A maximum oil yield of 46.8 wt% with the minimum char yield of 10.1 wt% was obtained by the treatment with 3 M H2SO4, whereas untreated wood samples resulted in a 30.1 wt% yield of oil. The main components in the oils were levoglucosan and tar. These results suggest that moderate acid pretreatment produced shorter chain units of cellulose, hemicellulose, and lignin, thereby facilitating the conversion into oil by pyrolysis. The results of thermogravimetry-mass spectroscopy supported the presence of shorter chain units in the pretreated wood samples.

Topics: Biofuels; Biomass; Biotechnology; Carbon; Catalysis; Cedrus; Cellulose; Glucose; Hot Temperature; Hydrocarbons, Aromatic; Hydrolysis; Lignin; Mass Spectrometry; Molecular Weight; Oils; Oxygen; Particle Size; Polysaccharides; Sulfuric Acids; Thermogravimetry; Trees; Wood

Anhydro sugars, produced during wood pyrolysis, can by hydrolyzed to sugars under acidic conditions. The acid hydrolysis of two common anhydro sugars in wood pyrolysis oils, levoglucosan (1,6-anhydro-beta-D-glucopyranose) and cellobiosan (beta-D-glucopyranosyl-(1-->4)-1,6-anhydro-D-glucopyranose), was investigated. Levoglucosan hydrolysis to glucose follows a first-order reaction, with an activation energy of 114 kJ mol(-1). For cellobiosan hydrolysis, 44% of the cellobiosan is hydrolyzed initially via the beta-(1-->4) glycosidic bond to form levoglucosan and glucose. The remaining cellobiosan is hydrolyzed initially at the 1,6 anhydro bond to form cellobiose. Both reactions are first order with respect to cellobiosan, with an activation energy of 99 kJ mol(-1). The intermediate levoglucosan and cellobiose are hydrolyzed to glucose.

Topics: Disaccharides; Glucose; Hydrolysis; Kinetics; Models, Chemical; Molecular Structure; Oils; Sulfuric Acids; Temperature