Ziegler-type nickel-based hydrogenation catalysts: The effect of the water content of the nickel precursor on the size and nature of the resulting particles

The size and nature of the nanoparticles forming in systems based on Ni(acac)2 · nH2O (n = 0, 0.5, 3.0) and AlEt3 have been determined by high-resolution electron microscopy and X-ray microanalysis. The nickel cluster size depends on the water content of the precursor. The average particle diameter increases from 1.2 nm (Ni(acac)2 · 0.5H2O precursor) to 2.4 nm (Ni(acac)2 · 3H2O precursor). A homogeneous solution forms in the Ni(acac)2–5AlEt3 system, as was demonstrated by examining the system under an electron microscope whose resolving power allows particles larger than 0.7 nm to be detected.