Roland Concin

Hydrothermolysis — a new process for the utilization of Biomass

SummaryIn the present paper a hydrothermolysis apparatus is described. The reaction vessel is of the percolator type with a volume of 560 cm3 and permits the hydrolysis of biomass materials up to 100 g. The optimum degradation conditions of pure cellulose (filter paper) were determined in dependence on temperature, flow rate of the eluting water and influence of stirring on the reaction mixture. Up to 52% glucose can be obtained by hydrolysing cellulose with pure water at 265°C at a flow rate of 12 cm3/min.Biomass materials such as poplar wood and wheat straw were hydrolysed in two stages, using temperatures of about 200°C for the easily hydrolysable polysaccharides and about 260°C for the polysaccharides, which are more difficult to hydrolyse. In the first stage on an average 45% of the initial amount is converted into soluble products, whereas in the second stage this value amounts to 48%.

Separation of phenols, phenolic aldehydes, ketones and acids by high-performance liquid chromatography

Abstract The high-performance liquid chromatographic separation of phenols, benzaldehydes, acetophenones, benzoic and cinnamic acids as well as some related compounds is described. An octadecyl silica column was used with a 0.01 M phosphate buffer-acetonitrile gradient as mobile phase. The retention times of the substances investigated depend on their polarity. An elution order depending on the basic functional groups and the substituents has been established.

Chromatographic analysis of biomass reaction products produced by hydrothermolysis of poplar wood

Abstract Poplar wood was treated under hydrothermal conditions at various temperatures the wide spectrum of reaction products was analysed by different liquid chromatographic methods. Low-molecular-weight compounds were investigated by means of high-performance liquid chromatography. Sugars and sugar decomposition products were analysed using a cation-exchange column; the separation of lignin degradation products was carried out by reversed-phase chromatography with gradient elution. The high-molecular-weight components were characterized by gel permeation chromatography (GPC). Oligomeric sugars were eluted from a gel column with water as the eluent. The molecular weight distribution of degraded lignin was obtained by GPC with a mixture of dioxane—water as the eluent. The application of the methods described does not require a time-consuming sample preparation. Therefore a rapid analysis and quantification of the reaction products is possible. This allows the investigation of the course of reaction and the calculation of the mass balance. In addition, the optimum process parameters can be evaluated from kinetic studies of the hydrothermolysis reaction.

Hydrolysis of Cellobiose in Dilute Sulpuric Acid and Under Hydrothermal Conditions

Abstract The sulfuric acid hydrolysis rate of cellobiose between pH 2 and 3 is directly proportional to the acid concentration. In good agreement with other authors, an activation energy of 133 kJ/Mol was found under these acidic conditions. The relation of the reaction rate constants for the glucose formation and glucose degradation (k1/k2) shows, in contrast to the hydrolysis of cellulose, little dependence on the temperature. Hydroxymethylfurfural, and to a lesser extent furfural, are glucose degradation products, which are also consumed but at a lower reaction rate than glucose. At pH values between 3 and 4.7 (pure water) strong deviations of the hydrolysis rates were observed. The formation of organic acids decreases the pH but has no influence on the reaction rate. This fact indicates that hydrothermolysis follows a reaction mechanism different from that of acidic hydrolysis.

Chromatographic behaviour of aromatic compounds on Sephadex LH gels : Calibration of gel columns for determination of molecular weight distributions

Abstract The chromatographic behaviour of phenols, phenolic acids, aromatic carbonylic compounds and cinnamic compounds on Sephadex LH gels is determined, and the dependence of the elution characteristics on the composition of the solvent, dioxane-water are reported. The results show that a dioxane-water composition of 7:3 causes the distribution coefficients to lie in a narrow range, in spite of the chemically different character of the investigated compounds. In pure dioxane strong adsorption effects are observed. In water-dioxane mixtures, however, partition effects occur when the water content is considerably higher than 30%. The results are used to design a gel chromatographic system for molecular weight determination using Sephadex LH gels and dioxane-water as eluent.

Analysis of oligomeric and monomeric carbohydrates from hydrothermal degradation of cotton-waste materials using HPLC and GPC

SummaryThe hydrolysis of different cotton materials under hydrothermal conditions was investigated. For the analysis of the resulting reaction products high-performance liquid chromatography and gel-permeation chromatography were applied. HPLC columns with ion exchange materials as stationary phases (HPX 87P and Shodex S801) enabled the separation of monomeric sugars and degradation products. Oligomeric sugars were analyzed using a gel column (Bio-Gel P-2) as well as a HPLC column (HPX 42A). Through identification of additional reaction products the mass balance of the hydrolysis can be improved and the analysis of the distribution of the oligomeric sugars gives information for the selection of the reaction conditions.

Separation and identification of monomeric lignin degradation products by g.l.c.-mass spectrometry

Abstract Hydrothermally degraded hydrochloric acid lignins were analyzed by g. l.c.-mass spectrometry. The low molecular weight compounds were extracted from the reaction mixture with cloroform and derivatized with BSTFA/TMCS (100:2). A quantitative derivatization was obtained after 1 hour at 70°C in a closed tube. The analyses of the silylated compounds were performed using a Varian MAT 44 S GCMS-system with a SE 54 glass capillary column in the GC (Varian 3700) connected to the quadrupole mass spectrometer by an open split coupling. Both deciduous wood lignin (poplar) and coniferous wood lignin (spruce) were analyzed. The GC-separations showed about 30 peaks of TMS derivatives for each lignin species, 20 of them were identified by their retention times and their mass spectra.

Activity Measurement of 14C-Labelled Plant Materials and their Hydrothermolysis Products

In order to measure 14 C in samples of biological origin by means of liquid scintillation counting, a series of methods has been developed [1 —6]. Absolute determination of activities by direct measurement is possible only in a few cases. Mostly the samples have to be transferred in a form suitable for counting (e.g. by solubilization, oxidation, combustion etc.). Our work comprised the cultivation of labelled biomass [7] for hydrolysis experiments and the measurement of solid, liquid and gaseous C labelled samples. The present paper describes the determination methods for both solid and liquid samples, compares the different methods and discusses their suitability.