Eeva Kuoppala

Characterization of biomass-based flash pyrolysis oils

Abstract An analytical scheme for the characterization of biomass-based flash pyrolysis oils was developed. The scheme was based on fractionation of the oils with water and on further extraction of the water-soluble fraction with diethylether. The chemical composition of the fractions was analyzed by gas chromatography–mass spectrometry. The physical and chemical nature of straw, pine and hardwood pyrolysis oils was determined and compared with each other. Correlations between the physical properties and chemical composition of the oils were drawn. The characterization method will be utilized in further work for stabilization and upgrading tests of flash pyrolysis oils.

Formation of the main degradation compound groups from wood and its components during pyrolysis

The thermochemical behavior of pine wood (Pinus sylvestris) and its main structural constituents (cellulose, hemicelluloses, and lignin) was investigated by pyrolysis-gas chromatography with mass-selective detection (Py-GC/MSD). In each case, major GC-amenable pyrolysis products were classified into several compound groups, and changes in the relative mass portions of these monomer-related fragments were monitored in the temperature range 400–1000 °C. The formation of the main products was shown to be characteristically dependent on the reaction temperature. The results also indicated that in the temperature range used, wood appeared to behave as the sum of its constituents.

Catalytic conversion of biomass pyrolysis vapours with zinc oxide

Conversion of pyrolysis vapours of pine sawdust was studied in micro and bench scales with zinc oxide catalyst. Three different zinc oxides were screened in a gas chromatograph system using an injection port as a fixed-bed catalytic converter in order to find appropriate reaction conditions by emphasising a high yield of bio-oil. Catalytically treated pyrolysis oils were produced in a side stream of an atmospheric fluidised bed pyrolyser (1 kg h−1) at the catalyst temperature of 400°C. The oils with silicon carbide treatment and without any catalyst were used as references. The aim was to study the catalytic effect of zinc oxide on the composition and on the stability of the oil. The pyrolysis liquids produced were homogeneous one-phase oils. The ZnO proved to be a mild catalyst and the liquid yields were not substantially reduced. It had no effect on the water-insoluble fraction (lignin-derived), but it decomposed the diethyl ether-insoluble fraction (water-soluble anhydrosugars and polysaccharides). Some indications of catalyst deactivation were observed. The oil samples were aged thermally and the variation of viscosity and water content were determined. The increase in the viscosity was significantly lower for the ZnO-treated oil (55%) than for the reference oil without any catalyst (129%). The results indicated an improvement in the stability of the ZnO-treated oil.

Py—GC/AED studies on the thermochemical behavior of softwood

Abstract The thermochemical behavior of sawdust from Scots pine ( Pinus sylvestris ) was investigated by pyrolysis—gas chromatography with atomic emission detection (Py—GC/AED). At temperatures of 400, 600, 800, and 1000 °C the conversion yields of the product fractions of volatile products (“light” and “heavy” fractions), condensable tars and char residue were determined. The use of the lower pyrolysis temperatures (400 and 600°C) yielded fewer volatiles (40–60% of the initial wood) than did the higher pyrolysis temperatures: the corresponding yield at 800 and 1000 °C was about 75% of the initial wood. The conversion yield of condensable tars remained relatively constant (25–35% of the initial wood) within the temperature range studied, whereas an increase in temperature reduced drastically the amount of char residue. The elemental analysis data for the two subfractions of volatile products indicated clear differences in the chemical compositions of these fractions. The content of the prominent gaseous components, carbon monoxide and carbon dioxide, in the “light” fraction of volatile products was measured by GC.

A novel test method for cracking catalysts

Abstract A novel microscale test method was developed for cracking catalysts. The pyrolysis unit was a commercial pyrolyser connected to a gas chromatograph. The injection port of the gas chromatograph was used as a fixed bed catalyst reactor. The test method was applied to cracking pyrolysis vapours of Scots pine sawdust with zeolites. Cracking of vacuum gas oil on a commercial FCC catalyst was used as reference. Detection of reaction products was carried out with a mass selective detector to identify the compounds or with an atomic emission detector to quantify the various elements. The results, in agreement with the literature indicate that the microscale pyrolysis and vapour-phase catalyst reactor was suitable for screening catalysts. Pyrolysis vapours were converted mainly into gases and aromatic hydrocarbons with zeolites. The zeolite catalysts were effective in the removal of oxygen but the liquid yields were low.

Organic compounds released in fluidized-bed drying of peat, bark and lignite

Abstract Organic compounds released in peat drying in a laboratory fluidized-bed reactor were analyzed by chromatographic methods in order to evaluate process operational and environmental aspects. For comparison, pine bark and lignite were also studied. Using steam as fluidizing gas, the release of condensable organic compounds comprised 2% and 25% of peat, calculated on a dry ash-free basis, when drying peat for 0.5 s at 190 and 350 °C, respectively. The corresponding release of noncondensable gaseous components was 1% and 6% at these temperatures, and carbon dioxide accounted for over 70% of the total non-condensable gases. The release of organic compounds at 250°C from peat was nearly four-fold and fifty-fold compared with that of bark and lignite, respectively. The organic materials released from peat were mainly aliphatic mono- and dicarboxylic acids (C 1 −C 28 ), methanol, aliphatic aldehydes, anhydroglucoses and furanoic compounds.

Characterization of condensates from peat and bark drying

Abstract An analytical system for determining the composition of condensates from the steam drying of peat and bark was developed. Both hydrophilic and lipophilic compounds could be separated by gas-liquid and liquid chromatographic methods. The dominant compound groups in the peat and pine bark condensates were carboxylic acids, aldehydes and monosaccharides, whereas the main compound groups detected in the birch bark condensate included carboxylic acids and terpenoids.