Currently millions of tons of hazardous chlorinated compounds are used for selective oxidation and bleaching reactions in the manufacture of pulp, paper, and commodity chemicals each year. Hydrogen peroxide (H2O2) represents a "green" alternative to chlorinated compounds, but it is not widely used because the current production method is economically viable only at very large scales. The proposed study will investigate an alternative catalytic approach - direct synthesis of H2O2 from hydrogen (H2) and oxygen (O2) gases - that would enable H2O2 production on-site for use in smaller, more common processing facilities. The proposed research is integrated with educational programs focusing on young women with emphasis on building research and research-mentoring skills.
The research will combine catalytic kinetic and in situ spectroscopic measurements in a systematic investigation to determine: 1) the mechanism for direct synthesis of H2O2, 2) the roles of surfaces, solvents, and liquid-phase intermediates in forming reactive intermediates, and 3) the combined effects of catalyst composition and solvent properties on reaction rates and selectivities. The initial work will focus on palladium (Pd) and palladium-gold (PdAu) clusters as the active catalytic materials, but learning derived from those materials will be used to generate guiding principles and activity descriptors to identify inexpensive alternatives to PdAu catalysts. To achieve these goals, a combination of kinetic and (ex situ and in situ) infrared spectroscopic techniques will be employed to probe the catalytic chemistry at the liquid-solid interfaces of supported metal clusters. This investigation will involve design parameters such as: size and composition of the metal clusters, the role of electrophilic adsorbates, and solvent properties such as pH and polarity. Although these studies specifically target the direct synthesis of H2O2, the work will develop tools and expertise needed for future investigations of a broad range of oxidative and reductive chemistries at liquid-solid interfaces.
