Advanced Separations Technology for Efficient and Economical
Recovery and Purification of Hydrogen Peroxide

Problem/Opportunity

Hydrogen peroxide (H2O2 ) is an effective oxidant that could be used in many industrial processes. Because the only by-product of oxidation using H2O2 is water, it could become the ultimate green chemical for the manufacture of many oxygenated petrochemicals. However, the current method for producing is inefficient and too costly.

The development of a new production process would represent a radical departure in the way that H2O2 is made and used. Not only could this be a simpler, more benign, and less expensive process, but it would also allow the development of new commercial applications and markets for H2O2 that are currently not competitive. A new process could also allow small-scale systems to be built on site, thus enabling rapid increases in capacity and point of use plants.

Development of an advanced porous, hydrophilic, and nafion membrane has the potential to simplify the manufacture of hydrogen peroxide and reduce capital and operating costs. These diagrams compare the process schematics for a conventional hydrogen peroxide process (Figure 1) relative to a simplified process (Figure 2) enabled by the new technology.

Approach

The objective of this project is to develop an efficient, economical, and safe process for the manufacture of H2O2 that employs advanced membrane separations technology with improved catalysts and processing technology. Argonne's main focus in the project was to develop novel membrane technology for separating aqueous H2O2 from mixtures containing organic hydrocarbon. This separations technology must attain high fluxes and selectivity for H2O2/water, achieve improved membrane stability and performance, and work well in combination with an integrated H2O2 production process. The industrial collaborators for this project, UOP and Unitel Technologies, have been working on various aspects of improved catalysts, organic formulations, and integrated process development. This program is supported by the U.S. Department of Energy/Office of Science (DOE/SC).

Results

Argonne's investigation of a filtration separation mechanism showed that aqueous H2O2 could be filtered away from an organic hydrocarbon phase by a range of porous hydrophilic membranes. A phenomenon termed the "wicking effect," in which the hydrophilicity of the membrane enables the establishment of an aqueous hydrophilic layer at the membrane and the pore surfaces, was also demonstrated. This effect enables high fluxes of the aqueous phase to be maintained even at low phase ratios of aqueous to hydrocarbon phases.

Having established these findings, the focus of the project at Argonne shifted to the development of porous, hydrophilic membranes and materials that would be stable to highly oxidizing conditions and also have controlled and definable pore structures. The approach that was selected was to develop porosity in existing Nafion membranes that are inherently stable.

Argonne developed a porous hydrophilic Nafion membrane that separated the aqueous H2O2 phase from the organic phase without significant flux loss even at low aqueous-to-organic-phase ratios. Repeated filtration tests of this new membrane over a 3-week period showed no significant decrease in flux. Small-angle neutron scattering spectroscopy conducted at the Argonne Intense Pulse Neutron Source facility showed that the new membranes that were porous had a new structure that was clearly different than the original membrane. A patent application "Microporous Perfluorinated Ionomer Membranes, Methods of Preparation Thereof" has been filed.

Future Plans

Work on the new membrane will continue with efforts to standardize the process to create porosity. We will also demonstrate the integration of the membrane into an improved H2O2 production process. Other existing porous membranes to which stable coatings have been applied will also be explored. Future funding from DOE/OIT has been obtained to continue the pre-commercial development of this new technology and identify other possible applications for such membranes.