Hydrogenation of dodecanoic acid over niobium oxide-supported Ir–Pd bimetallic nanoparticles

Abstract

Various combinations of Nb₂O₅-supported Ir-based catalysts (Ir‒X/Nb₂O₅, X= Mn, Fe, Co, Ni, Cu, Zn, Pd, Sn, and Au) were investigated for an efficient conversion of dodecanoic acid to dodecanol. The Ir and Pd combination; i.e. Ir‒Pd/Nb₂O₅, showed a higher conversion of dodecanoic acid (>90%) with a significant selectivity of dodecanol (>70%) when Ir:Pd ratio was 50:50 and 75:25 in comparison to the Nb₂O₅-supported monometal Ir or Pd catalyst. The synergistic enhancement could be explained as suppression of Ir aggregation and change of Ir reduction property in the presence of adjacent Pd. Based on the various support survey in the Ir‒Pd catalysts with MoO₃, SiO₂, α-Al₂O₃, ZrO₂ and Ta₂O₅, the contribution of Nb₂O₅ was unique in the catalytic reactivity. It was concluded that both Ir‒Pd alloying and electron-rich cation sites of Nb oxide comprehensively mediated the hydrogenation of midium-chain fatty acids to the corresponding alcohols.