The metal (Ni) impregnation was carried out with a nickel nitrate
(N97% Sigma Aldrich) aqueous solution (0.62 g of salt leads to 5%wt.
of Ni in relation to the final weight of the samples) on CA75MM,
CA75LM, CA90MM and CA90LM sorbents. The suspension of these
sorbents (2.5 g) in the nitrate nickel solution was kept under stirring
at 110 °C during 30 min to induce the evaporation of the solvent, then
the solid was collected, dried overnight at 100 °C and then calcined at
750 °C for 4 h, with a heating rate of 3 °C min−1.