Highly dispersed and ultra-small Ru nanoparticles deposited on silica support as highly active and stable catalyst for biphenyl hydrogenation

Abstract

• Ru/SiO 2 catalysts synthesized by SEA method exhibited highly dispersed Ru nanoparticles. • Bicyclohexyl yield achieved 99.9% at 90 °C and 1.0 MPa H 2 pressure for 80 min. • 1.5 wt.% Ru/SiO 2 catalyst showed excellent stability and reusability. • The excellent catalytic activity of 1.5 wt.% Ru/SiO 2 was explained with DFT calculation results. Liquid organic hydrogen carriers have been recently developed as the promising hydrogen storage materials, which exhibit significant advantages in hydrogen storage and utilization compared with the conventional hydrogen storage systems. Highly active and sable Ru/SiO 2 catalysts for biphenyl hydrogenation to form bicyclohexyl were synthesized through the strong electrostatic adsorption (SEA) method, and the conventional dry impregnation (DI) method was also considered as comparison. X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and H 2 -temperature-programmed reduction characterization techniques were used to investigate the physicochemical properties of the representative catalysts. The results showed that the catalysts synthesized by the SEA method possessed small-sized and well-dispersed Ru nanoparticles (NPs) on the silica support. Especially, 1.5 wt.% Ru/SiO 2 catalyst exhibited excellent catalytic activity, stability and reusability, where the initial turnover frequency (TOF) was 11.9 h −1 , the conversion of biphenyl was up to 99.9%, and the yield of bicyclohexyl reached 99.9% under the mild conditions (90 °C, 1.0 MPa H 2 ). Further density functional theory (DFT) calculations elucidate that the catalyst with small Ru nanoparticle size exhibits higher catalytic activity for biphenyl hydrogenation. Ru/SiO 2 catalyst synthesized by SEA method exhibited excellent catalytic performance for biphenyl hydrogenation