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Lech Nowicki and Maciej Markowski

Kinetic analysis of thermogravimetric data collected from bigger samples

Results for microcrystalline cellulose pyrolysis are presented, which includes thermogravimetric measurements and kinetic analysis of experimental data. The effect of sample mass size and heating rate on estimated values of activation energy and pre-exponential factor is demonstrated and a simple modification of procedure is proposed that allows for the correct values of kinetic parameters regardless of the experimental conditions. The efficiency of the proposed method is confirmed for two endothermic chemical reactions. A method of nonlinear regression is used for calculation of kinetic parameters for a single or TG curve or several curves simultaneously.

Open access

Tomasz Bedyk, Lech Nowicki, Paweł Stolarek and Stanisław Ledakowicz

Application of the TG-MS system in studying sewage sludge pyrolysis and gasification

A method of monitoring sewage sludge pyrolysis and gasification was proposed. Samples of sludge were pyrolysed in Ar and gasified in CO2 in a thermobalance. The evolved gases were analysed on the calibrated MS, the samples of sludge and solid residues at different stages of the processes were subjected to elemental analysis. The identification and the quantitative characterisation of chemical reactions were performed, based on the DTG and MS profiles.

Open access

Stanisław Ledakowicz, Lech Nowicki, Jerzy Petera, Jarosław Nizioł, Paweł Kowalik and Andrzej Gołębiowski

Abstract

The results of activity studies of four catalysts in methanol synthesis have been presented. A standard industrial catalyst TMC-3/1 was compared with two methanol catalysts promoted by the addition of magnesium and one promoted by zirconium. The kinetic analysis of the experimental results shows that the Cu/Zn/Al/Mg/1 catalyst was the least active. Although TMC-3/1 and Cu/Zn/Al/Mg/2 catalysts were characterised by a higher activity, the most active catalyst system was Cu/Zn/Al/Zr. The activity calculated for zirconium doped catalyst under operating conditions was approximately 30% higher that of TMC-3/1catalyst. The experimental data were used to identify the rate equations of two types - one purely empirical power rate equation and the other one - the Vanden Bussche & Froment kinetic model of methanol synthesis. The Cu/ZnO/Al2O3 catalyst modified with zirconium has the highest application potential in methanol synthesis.