The Catalytic Activity of Polyaniline in Hydrogenation Reactions with Molecular Hydrogen.

This study unveils a novel property of polyaniline by establishing its catalytic activity in heterogeneous hydrogenation with molecular hydrogen. Polyaniline was activated by heat-treating at different temperatures in a hydrogen atmosphere. The sample treated at 300 °C exhibited the highest catalytic activity for ethylene hydrogenation in the gas phase at atmospheric pressure and for p-nitrotoluene or α-methylstyrene hydrogenation in the liquid phase. XRD, HRTEM, Raman, XPS, UV-VIS, FTIR, and elemental analysis data as well as electrochemical study indicate that catalytic activity is associated with the conjugated structure of undoped emeraldine base, whereas the polymer cross-linking or an increase in chlorine residues correlates with catalyst deactivation. These results pave the way to use conducting polymers as catalysts for hydrogenation with molecular hydrogen, opening new avenues for their application in catalysis.