Hydroisomerization of long chain n-paraffins: the role of the acidity of the zeolite

Abstract

The transformation of n-hexadecane (n-C₁₆) was tested by two series of experiments over bifunctional catalysts with noble metal Pt and a one dimensional ZSM-22 zeolite to investigate the role of the acidity of the zeolite during the hydroisomerization of long chain n-paraffins. In series 1, varying the Si/Al ratio of the zeolite but fixing the zeolite content, reveals that the high acid strength of the zeolite can deteriorate the selectivity of the corresponding catalyst even at an initial conversion and that the low concentration of acid sites on the zeolite is beneficial to the improvement of the maximal value of the isomer yield. In series 2, varying the zeolite content but fixing the Si/Al ratio, reveals that the change of the zeolite content could not affect the selectivity of the catalyst. Both series 1 and series 2 revealed that the activity of the catalyst linearly increases with the acid strength, the concentration of acid sites and the content of the employed zeolite.