Kinetics of hydrogenation of cinnamaldehyde over alumina supported bimetallic Pd-Pt and Pd-Rh catalysts

Abstract

Kinetics of hydrogenation of cinnamaldehyde over Pd₅₀Pt₅₀ and Pd₄₀Rh₆₀ supported on AI₂O₃ have been studied. GC analysis and UV/vis spectrophotometric measurements have been used to identify the products and determine their concentrations. The products of this reaction, 3-phenylpropanal, 3-phenylpropanol and propylbenzene, are produced consecutively. The rate constants of the first step of this reaction over Pd₅₀Pt₅₀/AI₂O₃ and Pd₄₀Rh₆₀/Al₂O₃ are 1.88 x 10^{- 2}<i>M</i>^-1.5s^{- 1}g^{- 1} (metal) and 2.46 C 10^-2<i>M</i>^-1.5s^-1g^-1 (metal), respectively. The reaction order is 1 with respect to cinnamaldehyde and 1.5 with respect to hydrogen. The temperature variations in the range of 27-41°C have no significant effect on the reaction rates of both catalysts.