Noble metal nanoparticle (NPs) catalysts are attracting much attention for rapid and effective catalytic reaction in a wide range of industrial sites. Compared to classical colloidal heterogeneous catalysts, NPs provide higher surface area-to-volume ratios, which results in enhanced overall catalytic activities. Hydrogen peroxide (H2O2) is widely used as oxidizing agent, disinfectant, sanitizer and bleaching agent. It is commercially produced by an indirect process called by anthraquinone process. The direct synthesis of H2O2 from molecular H2 and O2 is gathering many researchers’ attention because the anthraquinone process produces concentrated H2O2, resulting in the associated storage and transport hazards. Moreover many applications require only dilute aqueous solutions on a small scale. Palladium (Pd) is well known as catalysts for direct H2O2 synthesis. Recently, various studies have been tried to improving catalytic activities by alloying Pd with other elements such as Sn, Ni and Au. Unfortunately, these high-performance bimetallic catalysts still utilize costly Pd. Therefore, there is a strong desire to develop inexpensive and efficient catalysts for direct H2O2 production, which can serve as an alternative to expensive Pd-based catalysts. We show that bimetallic materials which do not form intermixing phase between two elements can provide better H2O2-producing performances or lower costs than Pd materials. In our results, bimetallic catalysts have two domains in one nanoparticle, which carry out two different functions with synergy. One domain participates in dissociation of H2 and supply of hydrogen atoms, while the other domain takes part in supply of O2 suppressing O2 dissociation. In this way, new bimetallic catalysts are realized showing comparable catalytic activities with palladium. We synthesize bimetallic catalysts by the polyol reduction method. XRD and STEM-EDX clear evidence that there are not alloys but two domains in one nanoparticle. Therefore, new bimetallic catalysts can be cost-effective catalyst candidate for the replacement of Pd.

Catalytic properties of immiscible bimetallic catalysts for direct H2O2 synthesis

2019 Fall National Meeting

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