Ethylene-Stabilized Nanoparticles for Glycerol to Lactic Conversion

Lactic acid (LA) is an important platform molecule which can be converted into acrylic, 2,3-pentadione, 1,2 and 1,3 propandiol [1]. The demand of LA is steadily increasing due to its application as monomer for the production of the biodegradable poly(lactic acid). Most of the reported heterogeneous synthesis procedures employed in LA synthesis use supported metal nanoparticles in combination with air or oxygen as hydrogen acceptor. This latter synthesis approach leads to the formation of undesired side products, which stem from the oxidation of glyceraldehyde (i.e. key intermediate in LA synthesis from glycerol) [2]. Recently, we showed that the formation of the oxidation products can be circumvented upon replacing air or oxygen by ethylene pressure (Figure 1) [3]. Our catalytic system consists of Pt-nanoparticles (NPs), generated by the metal vapor synthesis technique, supported onto Ketjenblack (CK) (i.e. a high surface carbon support, 1400 m2/g) (Pt@CK). The contemporary presence of ethylene pressure during the catalytic glycerol to LA conversion avoided the aggregation of the Pt-NPs. As a consequence, high catalytic activity (780 h-1) and LA chemoselctivity up to 95% were obtained, which is the highest value found for a heterogeneous LA synthesis. Moreover, the heterogeneous catalyst showed in three consecutive runs a comparable catalytic performance. References [1]A. Corma, S. Iborra, A. Velty, Chem. Rev. 2007, 107, 2411-2502. [2]C. A. Ramirez-López, J. R. Ochoa-Gómez, M. Fernandez-Santos, O. Gómez-Jiménez-Aberasturi, A. Alonso-Vicario, J. Torrecilla-Soria, J. Ind. Eng. Chem. Res. 2010, 49, 6270-6278. [3]W. Oberhauser, C. Evangelisti, C. Tiozzo, F. Vizza, R. Psaro, ACS Catalysis 2016, 6, 1671-1674.