Materials for Energy, Efficiency and Sustainability: TechConnect Briefs 2015Materials for Energy, Efficiency and Sustainability TechConnect Briefs 2015

Nanomaterials for Catalysis Chapter 3

Carbonaceous Materials Supported-Pd Catalysts for the Enantioselective Hydrogenation of (E)-alpha-Phenylcinnamic acid: The Influence of Support Acidity

T.S. Bui Trung, Y. Kim, S. Kang, H. Lee, S. Kim
Korea Advanced Institute of Science and Technology (KAIST), Korea

pp. 115 - 119

Keywords: carbonaceous materials, Pd-based catalysts, enantioselective hydrogenation, sufface acidity, activated carbon, graphene oxide, carbon nanotubes

We performed a systematically comparative study of carbonaceous materials as catalyst supports for the asymmetric heterogeneous hydrogenation of (E)-alpha-phenylcinnamic acid to study the influence of the supports on the reaction enantioselectivity. We prepared Pd-based catalysts supported on activated carbon (AC), graphene oxide (GO), or carbon nanotubes (CNTs) by using deposition methods, and subsequently characterized their physicochemical properties. The results attained from the TGA, FT-IR, and TPD-NH3 analyses revealed an abundance of acidic sites present on the Pd/GO catalyst, which reduced significantly the enantioselective hydrogenation of PCA. The influence of the support acidity on the enantioselectivity was attributed to the preferential adsorption mode of the chiral modifier cinchonidine (CD) on the GO surface via electrostatic interactions between the positively protonated amine groups present in the CD molecule and the negatively charged oxygen functional groups present on the GO surface. Further investigations using functionalized CNTs as catalyst supports confirmed that the ee values increased linearly with the decrease of the acidic sites present on the supports.