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The liquefaction of biomass in ethanol, at the critical point, has high potential due to low temperature and pressure (243 °C, 63 bar) when compared with water (374 °C, 220 bar). The current study deals with the fractionation of birch wood powder which was liquefied under supercritical ethanol over acidic or non-acidic catalysts, 5 wt % Fe-Beta-H-150 and 5 wt % Fe–SiO 2 , respectively. Based on the results, the reaction mechanism for the formation of lignin degradation products was proposed. The main phenolic product was isoeugenol over 5 wt % Fe-Beta-H-150 while intermediate products, i.e. such as coniferyl, and sinapyl alcohol, 4-propenyl syringol, syringaresinol, as well as syringyldehyde reacted rapidly further. The thermodynamic analysis was performed by Joback approach and using Gibbs-Helmholtz equation supporting the obtained results. • Acidic 5 wt. % Fe-Beta-H-150 catalyst promoted the formation of isoeugenol. • A non-acidic Fe-SiO 2 and in the absence of catalyst the main products are sinapyl and coniferyl alcohol, respectively. • Enthalpy and Gibbs free energy for each reaction and equilibrium constants were calculated with product analysis results. [ABSTRACT FROM AUTHOR]

Hemicellulose O-acetyl-galactoglucomannan (GGM) is the main noncellulosic water-soluble polysaccharide in the coniferous softwood Norway spruce, consisting of anhydro-galactose, -glucose, and -mannose. Acid hydrolysis of GGM has been studied in a continuous tube reactor to obtain these sugars under industrially relevant conditions. The reaction was performed under atmospheric pressure at 90°C and 95°C, and hydrochloric acid (HCl) served as catalyst. The influence of the reaction parameters, such as acid concentration (pH), temperature, concentration of the substrate, as well as catalyst and reactant flow rates, has been studied on the conversion efficiency and product distribution. Continuous production of monomeric sugars was achieved without formation of low-molecular by-products. The GGM conversion was high with HCl as catalyst, at 95°C, and a pH of 0.3. The main hydrolysis products were mannose, glucose, and galactose monomers. Minor amounts of sugar dimers were detected among the products. The experimental results are described with a laminar flow model for the continuous reactor. [ABSTRACT FROM AUTHOR]

Arbutus andrachne and Platanus orientalis grow naturally in Turkey. They do not occur in stands but can be seen as solitary trees. A. andrachne is seen in coastal parts of Anatolia, whereas P. orientalis can be found from west to the east of Turkey, mostly in river banks. Lipophilic extractives, hydrophilic extractives, and suberin monomers from Arbutus andrachne and Platanus orientalis bark was analyzed by chromatography. The total amount of lipophilic extractives was higher in P. orientalis (8.55 mg/g). However, the total amount of hydrophilic extractives had a bigger proportion, 100.86 mg/g, in A. andrachne bark. Dioic and hydroxy acids were the dominant group in the suberin monomers of both species of bark. Acid 1,18-dioic-18:0 and acid 18-hydroxy-18:1 were determined as the main compounds of suberin monomers in both samples. In addition, total amount of suberin monomers was determined to be 11.36 mg/g in A. andrachne and 15.95 mg/g in P. orientalis bark. [ABSTRACT FROM AUTHOR]

For the first time, a tandem catalytic material, 5 wt % Pd/NbOPO 4 , was utilized in the depolymerization of wood in supercritical ethanol under hydrogen atmosphere. The experiments were conducted under various conditions, with fresh, and acetone extracted birch. A comprehensive analysis was performed to elucidate the dissolution efficiency and achieved product distribution. The results indicated that with fresh birch, 34 wt % of lignin monomer yield with 84 wt % delignification efficiency were obtained while with extracted wood, 35 wt % of lignin monomer yield with 78 wt % delignification efficiency were achieved. The total lignin monomer content extracted from the fresh birch is composed of 76.9 wt % of dimethoxyphenols and 16.5 wt % with the guaiacol structure. Major lignin monomer product was homosyringaldehyde (61.9 wt %). With extracted wood, 93.2 wt % of dimethoxyphenols (63.6 wt % homosyringaldehyde) and 6.8 wt % of guaiacol-monomers were achieved. It was concluded that the depolymerization occurred via breaking of the ether bonds in lignin, including ether hydrolysis by Lewis acid sites over the solid acid catalyst and with subsequent deoxygenation of monophenols over Pd. In addition, an extraction process was proposed to extract the aromatic fraction from the obtained biocrude. [ABSTRACT FROM AUTHOR]

The influence of oxygen (0–50 bar) on the molar mass and composition of hemicelluloses after hydrothermal treatment of spruce chips was studied in a batch reactor setup at 130 °C–160 °C. Purified galactoglucomannan was studied as a reference. The dissolved oxygen enhanced significantly the depolymerization of hemicelluloses from over 15,000 g/mol to 180 g/mol (monomers) as well as promoted acids formation from the monosaccharides. About 2–3 times faster depolymerization was observed already with rather low amounts of oxygen (2–8 bar), while the kinetics of depolymerization was significantly slower in inert atmosphere. The decrease in pH from neutral to as low as 2.5 lead to an autocatalytic effect on the polysaccharide hydrolysis and the consecutive reactions of monosaccharides. The results emphasize the importance of performing hydrothermal treatment under inert atmosphere if large polymeric hemicellulsoses are desired or if monosaccharides are targeted in hydrolysis of hemicelluloses. If autocatalysis begins, it is difficult to stop. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The changes in the amount and composition of suberin monomers of Scots pine outer bark, which is grown natively in Turkey, was investigated as a function of growing altitude. Samples were taken from every 100m to 1300m which was the highest point of the sampling area. While the total amount of suberin monomers is varied within the range 17.56–47.20mg/g, there was no correlation between total amount and altitude. Total amount of alkanols of suberin monomers decreased when the altitude increased. Alcohol 24:0 was seen as the dominant constituent and its amount decreased from 100m to 1300m. There was not a clear change in the total amount of alkanoic, dioic and hydroxy acids. Acid 1,18-hydroxy-18:1 and acid 1,18-dioic-18:1 were determined as the main compounds in all samples. [Copyright &y& Elsevier]