KINETICS OF THYMOL HYDROGENATION OVER A NI-CR2O3 CATALYST

The kinetics of thymol hydrogenation over commercial nickel-chromia ca talyst with formation of four menthol diastereoisomers have been inves tigated in a batch reactor at constant hydrogen pressure (0.4-4 MPa) a t temperatures between 373 and 433 K in n-hexane and cyclohexane solut ions. The rate of thymol consumption was independent of conversion. In itially mainly more thermodynamically unstable cis isomers (neomenthol and neoisomenthol) were produced and only at relatively high conversi ons trans isomers (menthol and isomenthol) were formed. However the st ereoselectivity values at a particular conversion were seen to be inde pendent of hydrogen pressure and reaction temperature. The observed ki netic regularities were modeled based on an elementary step mechanism.