Generation of hydrogen peroxide directly from H2 and O2 using CO2 as the solvent

Abstract

Hydrogen peroxide is a ‘green’ oxidant whose relatively high cost has prevented it from being applied to commodity chemical processing. In large part, those attributes of the current process (the anthraquinone route) that contribute to the cost of H₂O₂ also contribute to its non-sustainable features; by-product streams, energy input, and multiple required unit operations. We have explored the generation of hydrogen peroxide directly from hydrogen and oxygen using liquid CO₂ as the solvent and a CO₂-soluble palladium catalyst. Producing H₂O₂ directly from H₂ and O₂ eliminates unit operations and reduces raw material costs significantly. Further, homogeneous reaction in liquid CO₂ allows for contact between significant concentrations of O₂ and H₂, high rate of reaction, and ready recovery of the product via stripping into water. Both Pd(II) and Pd(0) catalysts were explored for the reaction; our results suggest that future work should focus on optimization of a CO₂-soluble or dispersible Pd(0) catalyst.