Xylene isomerization kinetic over acid-functionalized silicalite-1 catalytic membranes: Experimental and modeling studies

m-Xylene isomerization kinetics has been studied using acid-functionalized silicalite-1 catalytic membrane in the temperature range of 355-450 degrees C. Two types of catalytic membranes: (1) propylsulfonic acid-functionalized silicalite-1 membrane and (2) arenesulfonic acid-functionalized silicalite-1 membrane were synthesized on alpha-alumina support via one-step in situ hydrothermal crystallization and subsequent post-synthesis modifications. The membranes were characterized by scanning electron microscopy (SEM), ammonia temperature-programme desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FT-IR). Arenesulfonic acid-functionalized silicalite-1 membrane with its higher acidity gave better catalytic activity as compared to propylsulfonic acid-functionalized silicalite-1 membrane. The continuous removal of reaction products over the membrane contributed in the higher p-xylene yield. A triangular reaction scheme based on time on stream (TOS) model was used to analyze the experimental data. The simulated results were in good agreement with the experimental results, within an error less than +/- 5%. The estimated activation energies indicated that conversion of m-xylene to p-xylene in both acid-functionalized silicalite-1 membranes is affected by the mass transfer rate through the membrane, while conversion of m-xylene to o-xylene is controlled by the reaction rate. (C) 2010 Elsevier B.V. All rights reserved.