Effect of precursor on the catalytic behaviour of Ru-Cu/MgO

Ru-Cu/MgO catalysts, prepared using Ru(NO)(NO3)3 as ruthenium precursor, have been investigated in the hydrogenolysis of propane. Samples have been characterized by CO chemisorption and temperature-programmed reduction.On increasing the amount of Cu the catalytic activity initially decreases, reaching a minimum at about 20 at.% Cu, and then remains constant at higher Cu contents. A comparison with similar samples prepared from RuCl3 shows a different catalytic behaviour as a function of Cu content. It is suggested that the reduction temperature of the precursors, and therefore the rate of formation and growth of the metal crystallites, plays an important role in determining the degree of Ru-Cu interaction.