PNNL

Abstract

They hydrogenation, employing hydrogen gas, of cinnamaldehyde was performed using Pd-black and Raney Ni catalysis at 298± K in a water-cooled (jacketed) reaction vessel. Sampling at pre-determined time intervals and GC/MS analysis yielded time-dependent product state distribution information. A kinetic modeling of the data revealed that cinnamaldehyde was both hydrogenated to the final product benzene propanal, as well as a fraction being converted to the intermediate benzene propanal, where the latter was subsequently hydrogenated to benzene propanal. Comparing the ultrasound-assisted and blank (stirred) experiments revealed that a higher maximum relative concentration of intermediate benzene propanal was formed in the ultrasound experiments compared to the stirred experiment. The activities of the ultrasound experiments compared to blank were 9-fold and 20-fold greater for the Pd-black and Raney Ni catalysts, respectively. Finally, an application of Polayni’s principle to yield an estimate of the ratio of rate coefficients for benzene propanal and benzene propanal formation was performed by considering chemical group energy differences and surface adsorption energy differences in the first mechanistic step of hydrogenation.