Nickel nanoparticles in hydrogen-transfer reductions: Characterisation and nature of the catalyst

Nickel nanoparticles, readily prepared by reduction of nickel(II) chloride with lithium and a catalytic amount of DTBB, have been used in the transfer hydrogenation of carbonyl compounds and have been fully characterised by different means. The reaction rate of the transfer hydrogenation was found to be dependent on the acetophenone and isopropanol concentration but independent on the amount of lithium chloride. The deactivation of the catalyst after reuse has been mainly attributed to surface oxidation but not to coke formation. All the experiments performed are in agreement with the process being of heterogeneous nature. The nickel nanoparticles unveiled a superior behaviour in comparison with commercially available nickel catalysts.

Graphical abstractNickel nanoparticles used in the transfer hydrogenation of carbonyl compounds have been characterised by different means and their catalytic activity, deactivation and nature studied. Surface oxidation seems to be the main reason for catalyst deactivation after reuse. The nickel nanoparticles are the true catalyst instead of a reservoir for metal atoms that leach into solution.Figure optionsDownload full-size imageDownload high-quality image (111 K)Download as PowerPoint slide