Vol 66, No 1 (2025)

The effect of the content of supported manganese on the structural properties and activity in the oxidation reactions of CO and propane for the MnОx/Zr0.4Ce0.6 catalysts prepared by the impregnation method has been studied. It was found that an increase in manganese content to 3.6% wt. (molar ratio Mn/(Zr + Ce) ≤ 0.1) leads to an increase in the catalytic activity of MnОx/Zr0.4Ce0.6 in oxidation reactions. In the case of a higher manganese concentration, the activity changes slightly. According to the XRD, TPR-H2, XPS and EPR, an increase in the amount of supported manganese for samples with Mn/(Zr + Ce) ≤ 0.1 is accompanied by a change in the lattice constant of the support, an increase in the amount of weakly bound oxygen, as well as the quantity of oxygen vacancies in the structure of cerium oxide. These changes are due to the incorporation of manganese into the structure of the support and the possible formation of highly dispersed particles of MnОx on its surface which ensures an increase in catalytic activity. Stabilization of catalytic activity with a further increase in the amount of supported manganese correlates with a slight change in the amount of weakly bound oxygen and oxygen vacancies of the support due to the appearance and subsequent increase in the content of the less active Mn2O3 phase.

The effect of the content of supported manganese on the structural properties and activity in the oxidation reactions of CO and propane for the MnОx/Zr0.4Ce0.6 catalysts prepared by the impregnation method has been studied. It was found that an increase in manganese content to 3.6% wt. (molar ratio Mn/(Zr + Ce) ≤ 0.1) leads to an increase in the catalytic activity of MnОx/Zr0.4Ce0.6 in oxidation reactions. In the case of a higher manganese concentration, the activity changes slightly. According to the XRD, TPR-H2, XPS and EPR, an increase in the amount of supported manganese for samples with Mn/(Zr + Ce) ≤ 0.1 is accompanied by a change in the lattice constant of the support, an increase in the amount of weakly bound oxygen, as well as the quantity of oxygen vacancies in the structure of cerium oxide. These changes are due to the incorporation of manganese into the structure of the support and the possible formation of highly dispersed particles of MnОx on its surface which ensures an increase in catalytic activity. Stabilization of catalytic activity with a further increase in the amount of supported manganese correlates with a slight change in the amount of weakly bound oxygen and oxygen vacancies of the support due to the appearance and subsequent increase in the content of the less active Mn2O3 phase.

The experimental data on rice husk pyrolysis obtained by thermogravimetric method in non-isothermal mode were processed based on three-component kinetic model. According to the model, biomass is represented by the sum of three components — hemicellulose, cellulose and lignin. Pyrolysis of each component proceeds by independent irreversible first-order reaction. To determine the model parameters, the experimental data processing technique based on the difference in temperature ranges of hemicellulose, cellulose and lignin pyrolysis, improved in this work, was used. The activation energies of rice husk component pyrolysis were as follows: 21.3 kJ/mol for lignin, 110 kJ/mol for cellulose, and 38 kJ/mol for hemicellulose. The discrepancy between the experimental and calculated data on the sample mass was less than 1%. For comparison, the experimental data were processed using the one-component Ginstling–Brownestein model using the Coats–Redfern method.