Kinetics of hydrogen peroxide synthesis by direct combination of H₂ and O₂ in a microreactor

Hydrogen peroxide is an industrially important oxidant with a growing number of applications in the chemical and textile industries, and in environmental remediation. Production of H₂O₂ by the direct combination of H₂ and O₂ is much less energy-intensive than the currently used anthraquinone autoxidation method, but it has not been implemented commercially because of the explosive nature of H₂ and O₂ mixtures. In this work, hydrogen peroxide was safely produced by direct combination of hydrogen and oxygen in a microreactor in the explosive regime. Concentrations as high as 1.3 wt% H₂O₂ were achieved. Optimum ranges of the temperature and pressure for H₂O₂ production were determined, and the reaction was shown to be free of mass transfer limitations at the conditions of kinetic experiments. A plan for obtaining the overall kinetics of direct H₂O₂ formation is described, which involves the determination of rate expressions of H₂O₂ synthesis, and of consequent decomposition of H₂O₂. A mechanism for the H₂O₂ synthesis reaction is proposed on the basis of past research and kinetic data. A rate expression is derived based on the proposed mechanism, and kinetic data were used to calculate the kinetic constants. This is the first step toward the determination of complete kinetics of direct H₂O₂ formation.