A novel palladium catalyst for the synthesis of hydrogen peroxide from carbon monoxide, water and oxygen

Article abstract of DOI:10.1016/S1381-1169(99)00218-6

Hydrogen peroxide was synthesized from CO, water, and oxygen in a biphasic system using Pd complexes with bidentate nitrogen ligands as catalysts. The effect of the Pd ligand, acid cocatalyst, nature of solvent, temperature, and gas phase composition on the hydrogen peroxide yield and catalyst efficiency was studied. Among the phenanthroline derivatives, 2,9-dimethyl-4,7-diphenylphenanthroline was the most efficient ligand. The selected reaction medium, for catalysts comparison, was a mixture of water, 1-butanol, and 1,2,4-trichlorobenzene (a hydrophobic solvent added to improve the phase separation). The reaction was strongly accelerated by the presence of a water-immiscible alcohol that possibly played an active role in the reaction mechanism, acting as a ligand itself. The Pd complex with ligand 2,9-dimethyl-4,7-diphenylphenanthroline exhibited high stability and catalytic activity, with turnover number of ≤ 600 mole hydrogen peroxide/mole Pd-hr. The ligand structure, nature of the weakly-coordinating anion, and solvent played a key role in determining the catalytic activity and the operational stability of the complexes.