Effect of oxidative pre-treatment on hydrogen spillover for a Ni/SiO2 catalyst

•Ni catalysts prepared by the hydrazine method then calcined at 400°C were studied.•Activity of these catalysts increased with increasing degree of oxidation of nickel.•The metal active phase would be composed of an ensemble of Ni0 and NiO species.•Calcination treatment favors the reaction occurring on the nickel phase.