Kinetic Investigation of the Solvent-Free Hydrogenation of Dehydroisophytol

Isophytol is a key intermediate in the industrial synthesis of vitamins, produced by selective hydrogenation of dehydroisophytol. This work presents a study of the kinetics of this process in the absence of any solvent. The experimental data were modeled using power-law kinetic expressions and mechanistic models based on Langmuir–Hinshelwood kinetics. The hypothesis of noncompetitive adsorption between hydrogen and organics was chosen in order to describe the changes in the reactivity of the system at varying temperatures (313–353 K) and pressures (5.0–9.0 bar). A simplified approach was used to describe the kinetics of the overhydrogenation reaction to the corresponding alkane. A list of the relevant kinetic and adsorption parameters, the result of an optimization procedure, is reported. The mathematical model, successfully validated, allows the prediction of the influence of the operating conditions and of the addition of quinoline, as reaction modifier, on the selectivity of the process.