Jp. Mikkola et T. Salmi, Three-phase catalytic hydrogenation of xylose to xylitol prolonging the catalyst activity by means of on-line ultrasonic treatment, CATAL TODAY, 64(3-4), 2001, pp. 271-277
A novel concept fur improvement of the activity of recirculated Raney nicke
l catalyst by means of on-line ultrasonic irradiation was studied. Qualitat
ively, acoustic irradiation was clearly found to retard the catalyst deacti
vation in the three-phase hydrogenation of xylose to xylitol. Two different
intensities of the ultrasonic field were utilized in the experiments. The
hydrogenation kinetics was modeled with a semi-competitive reaction-adsorpt
ion model accounting for interstitital adsorption sites for hydrogen locate
d between larger organic molecules.
The deactivation of the Raney nickel catalyst was found to diminish notably
upon the use of on-line acoustic irradiation. Also, the selectivity of the
system was found to be improved by the use of ultrasound in comparison to
the case when no acoustic energy was dispatched to the system. The kinetic
model used in the fitting of the data was able to explain the experimental
concentrations fairly well. (C) 2001 Elsevier Science B.V. All rights reser
ved.