Highly-Ordered PdIn Intermetallic Nanostructures Obtained from Heterobimetallic Acetate Complex: Formation and Catalytic Properties in Diphenylacetylene Hydrogenation

Formation of PdIn intermetallic nanoparticles supported on alpha-Al2O3 was investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and hydrogen temperature-programmed desorption (H-2-TPD) methods. The metals were loaded as heterobimetallic Pd(mu-O2CMe)(4)In(O2CMe) complex to ensure intimate contact between Pd and In. Reduction in H-2 at 200 degrees C resulted in Pd-rich PdIn alloy as evidenced by XRD and the disappearance of Pd hydride. A minor amount of Pd1In1 intermetallic phase appeared after reduction at 200 degrees C and its formation was accomplished at 400 degrees C. Neither monometallic Pd or in nor other intermetallic structures were found after reduction at 400-600 degrees C. Catalytic performance of Pd1In1/alpha-Al2O3 was studied in the selective liquid-phase diphenylacetylene (DPA) hydrogenation. It was found that the reaction rate of undesired alkene hydrogenation is strongly reduced on Pd1In1 nanoparticles enabling effective kinetic control of the hydrogenation, and the catalyst demonstrated excellent selectivity to alkene.