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In this work, a ceria-zirconia supported nickel catalyst (Ni/CeZrO2) was for the first time used in a fluidized bed reactor in order to obtain carbon nanotubes (CNTs) and H2 in the reaction of the decomposition of CH4. The same catalyst was afterward regenerated with H2O, which was accompanied with the production of H2. The impact of catalyst granulation, temperature, and gas hourly space velocity (GHSV) on the amount and type of carbon deposits was determined using thermogravimetric analysis (TGA) and scanning and transmission electron microscopy (SEM and TEM). The presence of randomly oriented and curved CNTs with an outer diameter of up to 64 nm was proved. The Ni/CeZrO2 particles were loosely covered with CNTs, freely dispersed over CNTs, and strongly attached to the external CNT walls. TEM proved the presence of a Ni/CeZrO2@CNT hybrid material that can be further used as catalyst, e.g., in WGS or DRM reactions. The impact of GHSV on hydrogen production during catalyst regeneration was determined. The catalyst was subjected to cyclic tests of CH4 decomposition and regeneration. According to the obtained results, Ni/CeZrO2 can be used in CH4 conversion to CNTs and H2 (instead of CH4 combustion), e.g., in the vicinity of installations that require methane utilization.

In this study, the combustion behavior of raw waste wood from furniture and samples torrefied at temperatures of 473, 513, 553 and 593 K was investigated. TG-DTG analysis showed that the mass loss in the first stage of the process decreased with the temperature of torrefaction, whereas the temperature in the second stage increased. The influence of torrefaction and combustion parameters on greenhouse gas emissions were investigated by the FTIR technique. The characteristic combustion parameters were also determined. The ignition temperatures for the furniture wood waste and samples torrefied at 473, 513 and 553 K from 549 to 559 K, whereas that of the sample torrefied at 593 K was significantly higher (600 K). All samples were completely burnt at 813-843 K, after 29-35 min, depending on the torrefaction temperature. Kinetic parameters are determined using a two-step firstorder reaction. The activation energy value for the first stage increased with the increasing temperature of torrefaction, from 68 to 125 kJ mol -1 , whereas the temperature in the second stage decreased from 108 to 47 kJ mol -1 . A similar correlation was observed for the pre-exponential value A. In the case of the torrefied furniture wood waste at 593 K, the combustion process runs as a single first-order reaction. The calculated data were fitted to the experimental data very accurately (R 2 [ 0.9992 and standard deviation \6.7 %), and the kinetic model was correctly founded. The linear relationship between logA and E a provides a way to predict the kinetic parameters of the combustion process. Keywords

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