Microwave Assisted Polyol Synthesis of the Bimetallic RuRe Nanoparticles Deposited on γ-Alumina and their Application for the Light Alkane Oxidation

The RuRe nanoparticles (NPs) deposited on γ-Al₂O₃ were prepared in a one step by a microwave-polyol method and tested in the total oxidation of short chain alkanes under O₂-rich conditions. The used preparation method favored the formation of spherical metallic RuRe NPs with the mean particle size of 1.6 nm (Ru:Re = 90:10) and 2.1 nm (Ru:Re = 75:25), (HRTEM studies) and dispersion of 26 and 31 %, respectively (H₂ chemisorption data). The Ru nano-catalyst exhibited larger Ru NPs (2.9 nm) with lower degree of dispersion (19 %). The activity of the bimetallic RuRe nano-catalysts for the total oxidation of propane, used as a model compound, was higher compared to that of the Ru nano-catalyst. The superior catalytic performance of the former catalysts, especially of the sample with the low Re loading (1 wt%, RuRe = 90:10, 0.6–3 nm particle size), could be correlated with a high ruthenium dispersion (H/Ru = 31 %), i.e., the high surface area of the Ru phase available for reaction, and to the higher intristic activity caused by the synergy effect between Re and Ru. Moreover, the RuRe nano-catalysts exhibited better stability with respect to the Ru nano-catalyst under used reaction conditions.