Direct synthesis of hydrogen peroxide in methanol and water using scCO 2 and N 2 as diluents

Direct synthesis of hydrogen peroxide is of high importance nowadays due to its improvement over the traditional anthraquinone hydrogenation-oxidation process. In this work we show how H2O2 can be obtained from H2 and O2 in water pressurised with CO2 under supercritical conditions or with N2 at similar conditions without using organic solvents. Pressures up to 16.7 MPa and mild temperatures from 10 to 45 °C using a commercial 5 wt.% Pd/C catalyst lead to yields from 10.8% to 82.6%, concentrations from 0.22 to 4.01 wt.% of H2O2 and Turn Over Frequency at 30 minutes values, TOF30, from 6.0 to 1538 mol·h−1·kgcat−1. The effect of several variables on H2O2 yield has been examined: amount of catalyst, promoters/Pd ratio, amount and nature of solvent and inert gas, reaction temperature, and O2/H2 ratio. Results for methanol and water are compared.