Pyrolysis of a wood chips mixture and main wood compounds such as hemicellulose, cellulose and lignin was investigated by thermogravimetry. The investigation was carried out in inert nitrogen atmosphere with temperatures ranging from 20°C to 900°C for four heating rates: 2 K min−1, 5 K min−1, 10 K min−1, and 15 K min−1. Hemicellulose, cellulose, and lignin were used as the main compounds of biomass. TGA and DTG temperature dependencies were evaluated. Decomposition processes proceed in three main stages: water evaporation, and active and passive pyrolysis. The decomposition of hemicellulose and cellulose takes place in the temperature range of 200–380°C and 250–380°C, while lignin decomposition seems to be ranging from 180°C up to 900°C. The isoconversional method was used to determine kinetic parameters such as activation energy and pre-exponential factor mainly in the stage of active pyrolysis and partially in the passive stage. It was found that, at the end of the decomposition process, the value of activation energy decreases. Reaction order does not have a significant influence on the process because of the high value of the pre-exponential factor. Obtained kinetic parameters were used to calculate simulated decompositions at different heating rates. Experimental data compared with the simulation ones were in good accordance at all heating rates. From the pyrolysis of hemicellulose, cellulose, and lignin it is clear that the decomposition process of wood is dependent on the composition and concentration of the main compounds.

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The present work deals with thermo-catalytic decomposition of pyrolytic oil from the scrap tire pyrolysis process. Such oil can be used as a model tar in an experimental study of tar removal from pyrolysis or gasification process gas. Several experiments under different conditions were carried out in order to determine conditions of the gasification and pyrolysis processes. Influence of the oil to steam ratio, temperature, and of the presence of dolomite catalyst was studied. Addition of water steam has positive effect on the hydrogen content in the outgoing process gas as well as on the conversion of the injected oil. The catalytic gasification experiment in a quasi steady state produced process gas with the composition: 61 mole % of H2, 6.4 mole % of CO, and 11.7 mole % of CH4. At temperatures lower than 800°C, the amount of process gas decreased resulting also in a decrease of the oil conversion. A comparison of gasification experiments using fresh calcined dolomite with experiments proceeding with regenerated dolomite was done under the same conditions. There was a decrease in the process gas volumetric flow when regenerated catalyst was used.

Activated sewage sludge samples obtained from two different waste water treatment plants were investigated by thermogravimetric analysis. Due to a very high content of water in the sludge samples, these had to be dried at 160°C in an electrical oven in order to remove all adsorbed water. To ensure pyrolysis conditions, nitrogen atmosphere was applied. The pyrolysis decomposition process was carried out in the temperature range from ambient temperature to 900°C at three different heating rates: 2 K min−1, 5 K min−1, 10 K min−1. TGA and DTG curves of the decomposition processes were obtained. Temperature of onset decomposition, final temperature of decomposition, maximum decomposition rate, and decomposition temperature were determined by thermogravimetric analysis for both sludge samples used. The main decomposition process takes place at temperatures in the range from 230°C to 500°C. Above this temperature, there are only small changes in the mass loss which are often attributed to the decomposition of carbonates present in the sewage sludge samples. To determine the apparent kinetic parameters such as the activation energy and the preexponential factor, the so called Friedman isoconversional method was used. Because of the requirements of this method, initial and final parts of the decomposition process, where crossings of the decomposition lines occurred, were cut off. Obtained dependencies of the apparent activation energies and preexponential factors as a function of conversion were used backwards to calculate the modeled decomposition process of sewage sludge and the experimental data were in good accordance with the data obtained by simulation.

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