(247f) Silica-Supported Ruthenium Nanoparticles for Hydrogenation of Pyruvic Acid In the Aqueous Phase

Heterogeneous catalysis is an important technology in the chemical industry. Incorporation of nanoscience into catalysis provides one of the most powerful approaches to understanding reaction mechanisms and designing new-generation catalysts more efficienctly¹. In this work, we present a strategy for design of monodisperse Ruthenium nanoparticles (RuNPs), immobilization of the  RuNPs onto ordered mesoporous silica (MSUF), and reactivity assessment of the supported catalyst (RuNPs/MSUF) by aqueous phase hydrogenation of pyruvic acid to lactic acid. The RuNPs were prepared by a polyol reduction method² using ruthenium(III) acetylacetonate and poly(vinylpyrrolidone) (PVP) as precursor and stabilizer, respectively. Transmission electron microscopy (TEM) characterization showed that the particles were spherical with a fairly narrow size distribution and an average diameter of 3.5±0.5 nm. RuNPs/MSUF was prepared by immobilizing the RuNPs onto ordered mesoporous silica support MSUF using sonication method. RuNPs/MSUF was prepared by immobilizing the RuNPs onto ordered mesoporous silica support MSUF using sonication. TEM characterization showed well-dispersed particles on the surface of MSUF with no agglomeration and no damage to the framework of the support. Both inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and X-ray photoelectron spectroscopy (XPS) characterization confirmed the attachment of RuNPs to MSUF. The reactivity of RuNPs/MSUF was evaluated by aqueous phase hydrogenation of pyruvic acid. All the reactions were conducted in a multi-batch reactor system (Parr Instrument Co., Model 5000), and the samples were analyzed by HPLC (Waters Co.) with an RI detector. A differential approach was used to compute the initial turnover frequency (TOF) for each reaction^3,4. Results showed that, even under much milder reaction conditions than reported to-date⁵, the initial TOF of the reaction (685.2 h^-1) catalyzed by RuNPs/MSUF is more than 25 times higher than values reported in the literature (24.2 h^-1)⁵.  It is also noteworthy that RuNPs/MSUF shows a significant improvement in TOF compared to commercial Ru catalysts, which is an indication of a higher utility efficiency of Ru in catalysis.

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