Catalytic behavior of bimetallic Ni–Fe systems in the decomposition of 1,2-dichloroethane. Effect of iron doping and preparation route

Abstract

Model bimetallic Ni–Fe catalysts were prepared by coprecipitation from aqueous solutions of nitrates and by mechanical alloying of metal powders. Pure nickel samples subjected to the similar procedures were used as references. The obtained samples were characterized by scanning electron microscopy and X-ray diffraction analysis. Catalytic chemical vapor deposition of 1,2-dichloroethane over the catalysts was studied in a quartz flow reactor equipped with a McBain balance. It was shown that in the case of coprecipitation followed by reduction, Ni–Fe solid solution is formed within the studied range of Fe loading (1–10 wt%). Activation times of 6 min and longer are required to obtain this solid solution by the mechanical alloying method. Despite the known catalytic activity of nickel and iron in hydrocarbon decomposition in accordance with carbide cycle mechanism, iron doping was found to worsen the behavior of nickel in the studied reaction where chlorinated alkane plays a role of substrate to be decomposed. The formation of thermodynamically more stable iron chloride in relation to nickel chloride leads to deactivation of the catalyst and deceleration of the overall process.