Enhancement of catalytic activity of Pd-PVP colloid for direct H₂O₂synthesis from H₂and O₂in water with addition of 0.5 atom% Pt or Ir

Abstract

Atomically dispersed Pt or Ir atoms enhance H2O2 and H2O formation on Pd nano-particles leaving the H2O2 hydrogenation rate unchanged, while Ru, Rh, or Au atoms show little effect.

Looking for the “Dream Catalyst” for Hydrogen Peroxide Production from Hydrogen and Oxygen

“…Enhanced productivity and selectivity were observed upon addition to Pd of another noble metal, more often Au [40][41][42][43][44][45][46]. It has also been demonstrated that the combination of Pd with Ir [47], Ag [48,49], and Pt [50] can improve both the productivity and the selectivity of the process. On the contrary, the presence of Rh and Ru increased H 2 O 2 decomposition activity of Pd catalysts [51].…”

“…Also by DFT calculations, Deguchi et al [47] found that the adsorption energies of H 2 , O 2 , H 2 O 2 , and HBr were larger on coordinatively more unsaturated sites (such as corners and edges) than on more saturated sites such as a {111} facet. The energy profiles of the H 2 + O 2 reaction suggested that H 2 O 2 would be smoothly produced on more saturated sites such as the {111} facet.…”

Recent Advances in the Direct Synthesis of H2O2

“…Edwards et al . were the first to report increased catalytic activity towards H 2 O 2 formation when alloying Au and Pd, building on these initial findings subsequent investigation of Pd‐based, bi‐ and tri‐metallic catalysts for the direct synthesis reaction with numerous combinations of catalysts since reported, including; Pd−Pt, Pd−Ru, Pd−Rh,, Pd‐Ir and Au−Pd‐Pt ,…”

“…has investigated the effect of precious metal (Au, Pt, Ru, Rh and Ir) addition to a Pd‐polyvinylpyrrolidone colloid, with dramatic enhancements being observed with the addition of very low (0.5 at. %) concentrations of Pt or Ir doubling the formation rate of H 2 O 2 . Kinetic analysis, supported by DFT studies, indicated that the high H 2 activating abilities of Pt and Ir were responsible for the enhanced H 2 O 2 synthesis reaciton rate, while the subsequent H 2 O 2 hydrogenation rate remained fairly constant with Pt and Ir incorporation, indicating that the H 2 * activated on Ir or Pt played little role in the degradation of H 2 O 2 .…”

Gold–palladium colloids as catalysts for hydrogen peroxide synthesis, degradation and methane oxidation: effect of the PVP stabiliser

“…35 Recent studies by Deguchi et al have shown that a range of bimetallic colloidal particles stabilised with PVP, including Pd-Ir and Pd-Pt, can be active catalystshowever the role of the polymer additive in all these cases has not been explicitly addressed. 36 Recently we demonstrated that using colloidal AuPd nanoparticles stabilised with PVP, it was possible to achieve selective oxidation of methane to methanol at 25-50°C with O 2 incorporation using H 2 O 2 as an initiator. 37 A significant result in this study showed that the background H 2 O 2 decomposition rate was minimal for unsupported colloidal AuPd-PVP particles at 50°C, allowing the radical reaction process to propagate rather than terminate; however the H 2 O 2 decomposition rate increased significantly when then the same particles were supported on TiO 2 making this an ineffective catalyst.…”