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 H-2 and O-2 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 O-2 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. (c) 2007 Elsevier B.V. All rights reserved.