The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl₂ reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al₂O₃ catalysts. The effect of temperature and time on NiO and NiCl₂ reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl₂ reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al₂O₃ catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina‐based foam and prepared via aerosol route. Properties of the samples before and after low‐temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al₂O₃ catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni‐Pd/Al₂O₃ catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K.

The aim of this study was comparative analysis of catalysts with 5 and 20 wt. % Ni loading, with and without Pd additive, and it included: determination of reduction degrees, investigation on microstructure by scanning electron microscopy and chemical analysis by energy-dispersive spectroscopy. Ni/Al2O3 and Ni-Pd/Al2O3 catalysts supported on ?-Al2O3-based foams were synthesized by aerosol assisted impregnation. Impregnation of the foams by ultrasonically aerosolized chlorides was followed by drying at 473 K and hydrogen reduction at 533 and 633 K. Lower Ni loading resulted in higher reduction degrees. Ni loading of 20 wt. % enabled relatively uniform coverage of the foam with a metallic coating. With activity modifier (Pd), nearly complete reduction was achieved at both temperatures. Reduction degrees reached 99.4 and 98.2 wt. % at 533 K for 5 and 20 wt. % of Ni, respectively.

The aim of this study was to investigate a possibility of synthesis of porous ceramics with controlled open porosity, which could be used as sorbents and catalyst supports. Two organic additives were used to obtain open porosity: polystyrene beads and cellulose fibers, which are mixed with kaolin clay powder and the appropriate water content. Samples were sintered at 1050?C for 1 h. Characterization of the obtained products included X-ray powder diffraction analysis (XRPD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and elemental CHNS analysis. In addition, porosity was examined by quantification of visual information. The specific surface areas were determined by the Brunauer?Emmett?Teller (BET) method. Also, density and compressive strength of the obtained samples were assessed. It was determined that by sintering, the organic component completely leaves the system. For samples prepared with polystyrene beads and with cellulose fibers, satisfactory mechanical properties were obtained: compressive strengths were 1.42 and 1.56 MPa, respectively. It was noted that significantly higher open porosity was obtained by using polystyrene beads as a sacrificial template (porosity of ~56 %) instead of cellulose fibers (porosity of ~6 %).