A comparative analysis of catalysts with 5 and 20
wt.% of Ni, with Pd and without additive, was conducted.
The catalysts were supported on α-Al2O3-based
foams and prepared by aerosol assisted impregnation.
Before hydrogen reduction, samples with 5 wt.% of Ni
had submicron-sized, non-agglomerated, isolated NiCl2
particles. Cracked NiCl2 crust enveloped the whole
foam surface in the case of 20 wt.% of Ni. Higher
reduction degrees were reached with lower Ni loading
at 533 and 633 K. Reduced Ni/Al2O3 and Ni–Pd/Al2O3
samples had similar microstructures for the same Ni
content. With 5 wt.% of Ni, isolated, island-like, submicron-
sized particles were formed. Sample with 20
wt.% of Ni had metallic coating without agglomerates
and visible cracks that relatively evenly covered the
whole foam surface. Ni–Pd/Al2O3 catalysts were nearly
completely reduced at both temperatures. Their reduction
degrees reached 99.4 and 98.2 wt.% for 5 and 20
wt.% Ni loading, respectively, at 533 K. Optimal metal
loading in the produced catalysts is 20 wt.% of Ni and
the addition of 0.1 wt.% Pd because the foam surface is
relatively uniformly covered with metallic coating.
Obtained results indicate that Ni-based catalysts, modified
with Pd, can successfully be synthesized without
the calcination step and can be reduced at lower temperature.