Monitoring the structural and textural changes of Ni-Zn-Al hydrotalcites under heating

• Published in: Thermochimica acta 2020-05, Vol.687, p.178594, Article 178594
• Main Authors: Meza-Fuentes, E., Rodriguez-Ruiz, J., Solano-Polo, C., Rangel, M.C., Faro, A.
• Format: Article
• Language: English
• Subjects: Activation energy; Hydrotalcite decomposition; Nickel oxide
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2020.178594

[Display omitted] •Heating of nickel-based hydrotalcites led to structural changes and NiO formation.•a0 and c0 parameters decreased due to the heating of hydrotalcites.•The collapse of the structures was recorded at lower temperatures in solids containing zinc.•The solids were mesoporous with interparticles mesopores and shapes that depend on the composition of the solid. The structural changes of nickel-aluminum and nickel-zinc-aluminum hydrotalcites under heating were studied. The temperature and the activation energy required for hydrotalcites decomposition and NiO formation depend on the kind and on the amount of cations. Upon heating, the cell parameters and the crystal sizes changed, aluminum and zinc delaying crystal sintering and zinc leading to the smallest crystals of nickel oxide. The increase of aluminum and/or zinc content decreases the crystals size of hydrotalcites but zinc decreased the specific surface area. The zinc-containing solids produced oxides at lower temperatures while the zinc-free solids were the most thermally stable, possibly due to the increase of a parameter caused by the larger ionic radius of zinc. All solids were mesoporous with interparticles mesopores, whose shape depends on the composition of the solids and the conditions of collapse of the hydrotalcite type structure.