The reducibility of highly stable Ni-containing species in catalysts derived from hydrotalcite-type precursors

A study was conducted on the speciation and reducibility of Ni in catalysts derived from hydrotalcite-type (HT) precursors intercalated by silicates. Silicate and nickel contents in Ni/Mg/Al HT precursors varied and the products obtained by thermal decomposition in the 773–1373 K range were characterized. Sample properties were related to the amount of silicates and nickel. The former altered the formation of the spinel-type phase and decreased the ratio between MgO and MgAl2O4 phases in which the active species were stabilized. On the other hand, the Ni distribution depended on the Ni-loading. Nicontaining species in the spinel phase were more abundant for high Ni-loaded catalysts, and were readily reduced by H2 treatment at 1023 K, whereas those in the Ni1xMgxO solid solution remained partially unreduced.