Applicability of nickel-based compounds as catalysts for thermal conversion of primary biomass pyrolysis products

The paper discusses the results of an experimental study of the thermal decomposition of pyrolytic tar carried out in isothermal conditions at temperatures of 300, 350 and 400 °C. It was found that the kinetics of this process can be described using the Avrami–Erofeev equation with a variable parameter n. Analysis of the established data showed that the area of variation of this index included values from 0.415 to 1.238. The mean value of the n parameter calculated for all variants of the study was 0.694 (95 % CI from 0.605 to 0.783), and the median value was 0.639. As is known, the Avrami–Erofeev equation describes the kinetics of thermal decomposition of matter in the condensed state, determined by the nucleation process. This suggests that in the case of thermal decomposition of pyrolytic tar in the temperature range 300–400 °С this process is the limiting stage of the total process. The pyrolytic tarn decomposition rate was found to increase in the case of introduction of particles of nickel catalyst developed at the Physical and Technical Institute of the National Academy of Sciences of Belarus into the reaction zone. However, only with respect to one sample, it can be confidently stated that this is the result of the catalytic effect of applied nickel catalyst. Based on the established data, it was concluded that it is promising to use a nickel-containing catalyst in the processes of thermal decomposition of heavy hydrocarbons formed in the processes of thermochemical conversion of biomass.