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

Kinetics of hydrogenation of cinnamaldehyde over Pd50Pt50 and Pd40Rh60 supported on Al2O3 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/Al2O3 and Pd40Rh60/Al2O3 are 1.88 X 10(-2) M(-1.5) s(-1) g(-1) (metal) and 2.46 X 10(-2) M(-1.5) s(-1) g(-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 degrees C have no significant effect on the reaction rates of both catalysts.