Kinetics of NiO and NiCl₂ Hydrogen Reduction as Precursors and Properties of Produced Ni/Al₂O₃ and Ni‐Pd/Al₂O₃ Catalysts

Abstract

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.

In SituShell‐Isolated Nanoparticle‐Enhanced Raman Spectroscopy of Nickel‐Catalyzed Hydrogenation Reactions

“…However, due to the limited stability of Au@SiO 2 at high temperatures and the practical limitations of the Linkam Cell brought about by the high heat capacity of H 2 , the maximum temperature that can be reliably achieved is 400 °C. For the precursor samples we have chosen to eliminate a calcination step as the reduction of nickel oxide occurs at even higher temperatures than the direct reduction of the herein used Ni precursors …”

Ni-Pd-Al2O3 catalyst supported on reticulated ceramic foam for dry methane reforming

“…Utilization of chlorides instead of oxide precursors that are obtained by calcination can enable lower energy consumption because the calcination is avoided during the production of Ni-based catalysts [16]. Moreover, kinetic analysis of NiO and NiCl 2 hydrogen reduction confirmed that the oxide phase is more stable and less reducible than the chloride phase [18].…”

“…Chloride precursors for metals were almost completely reduced by hydrogen at 533 K. Utilization of chlorides instead of oxides in the production of catalysts can provide energy savings due to elimination of the calcination [16]. In addition, chlorides have higher reducibility than oxides obtained by calcination [18].…”

Synthesis of novel WO3/ZrSiO4 catalysts for dehalogenation of halogenated hydrocarbons

“…Despite obtaining high-performance catalysts, thermo-chemical synthesis routes are complex from a cost-effective point of view: they last from 30 to 50 hours or even up to a few days and require large amounts of complex chemical composition solutions [2,[4][5][6][7][8][9][10]. Hence, it is highly desirable to simplify the catalyst production processes by reducing the number of process stages and in conjunction also achieve a lower environmental impact when compared with the thermo-chemical synthesis routes [11][12][13].…”