Uniform Mesoporous Silicoaluminophosphate Derived by Vapor Phase Treatment: Its Catalytic and Kinetic Studies in Hydroisomerization of 1-Octene

Ordered mesoporous silicoaluminophosphate (MESO-SAPO-34) assembled from microporous SAPO-34 precursor was stabilized by post synthesis vapor phase treatment. The resultant MESO-SAPO-34 possessed uniform mesoporosity, high surface area, pore volume, and strong acidity. The resultant materials were studied as catalysts for the hydroisomerization of 1-octene and showed excellent conversion, and a maximum branched isomer selectivity of about 52% was achieved at low weight hourly space velocity (WHSV). Kinetic models based on Langmuir–Hinshelwood–Hougen–Watson (LHHW) mechanism were developed to describe the hydroisomerization of 1-octene, and the kinetics and adsorption parameters were estimated. A nonlinear regression based on modified Levenberg–Marquardt algorithm was used to estimate the parameters, and the model values were found to compare well with the experimental values. Parameters obtained from the LHHW model show that the conversion of 1-octene to other linear octenes requires low activation energy, whereas the conversion of linear octene to branched octene demands the highest activation energy. The enthalpy and entropy of adsorption obtained from Arrhenius plots were found to be consistent with thermodynamics.