-The effect of the addition of Mg and Ca to Ni/ -Al 2 O 3 catalysts was studied, aiming to address their role as promoters in the steam reforming reaction. Temperature-programmed reduction and H 2 and CO temperature-programmed desorption experiments indicated that Mg interacts with the metallic phase. Mg-promoted catalysts showed a greater difficulty for Ni precursor reduction besides different probe molecule (H 2 and CO) adsorbed states. In the conversion of cyclohexane, Mg inhibited the formation of hydrogenolysis products. Nonetheless, the presence of Ca did not influence the metallic phase.

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