Kinetics of NiO and NiCl(2) Hydrogen Reduction as Precursors and Properties of Produced Ni/Al(2)O(3) and Ni-Pd/Al(2)O(3) Catalysts

The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl(2) reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al(2)O(3) catalysts. The effect of temperature and time on NiO and NiCl(2) 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 NiCl(2) 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/Al(2)O(3) 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/Al(2)O(3) 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/Al(2)O(3) 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.