Catalysis Letters, Vol.129, No.1-2, 93-103, 2009
Application of the Selective Energy Transfer Model to Account for an Isokinetic Response in the Gas Phase Reductive Cleavage of Hydroxyl, Carbonyl and Carboxyl Groups from Benzene Over Nickel/Silica
The gas phase hydrodeoxygenation of a series of aromatic alcohols, aldehydes and acids has been examined over Ni/SiO2. Compensation behaviour is established with an isokinetic temperature (518 +/- A 21 K) that is consistent with with the point of intersection of the Arrhenius lines. This is accounted for using the Selective Energy Transfer model that is based on resonance between the catalytic Ni-H vibration and out-of plane C-H vibrations of the aromatic reactants with a transferral of resonance energy from the catalyst to generate the "activated complex". The calculated wave number of this vibration mode is 720 +/- A 29 cm(-1) with an associated anhamonicity of -3.3 +/-A 0.9 cm(-1). Our analysis suggests that the oxygenated aromatic is weakly adsorbed on the catalyst and surface mobility facilitates reaction with adsorbed hydrogen atoms.
Keywords:Isokinetic temperature;Selective energy transfer model;Anharmonicity;Catalytic hydrodeoxygenation;Ni/silica