Hydroisomerization of Long Chain n-Paraffins over Pt/ZSM-22: Influence of Si/AI Ratio

Hydroisomerization of n-hexadecane has been investigated over ZSM-22 framework by varying bulk molar Si/Al ratio in the range from 30 to 90 at constant platinum loading of about 0.45 wt %. Thus, ZSM-22 samples have been synthesized and characterized with respect to their crystallinity, textural parameters, and total acidity by means of X-ray diffraction, nitrogen adsorption desorption isotherm measurement at 77 K, and temperature-programmed desorption of ammonia technique, respectively. The effect of hydroisomerization reaction parameters, namely, temperature and weight hourly space velocity (WHSV), on n-hexadecane isomer selectivity and yield has been investigated. The optimal results over prepared catalysts demonstrated the best possible performance over ZSM-22 framework with bulk molar Si/Al ratio of 45, wherein the C-16 product with isomer selectivity and yield (82.7 and 74.8%, respectively) and pour point of 252 K have been achieved at a conversion level of about 90% at 578 K. Based on the obtained results, the possible advantages of using ZSM-22 (bulk molar Si/Al similar to 45) framework cold flow property improvement of long chain n-paraffins can be envisaged.