Optimizing the Acid Properties of the HZSM-5 Catalyst for Increasing the p-Xylene Yield in 1-Hexene Aromatization

For increasing p-xylene (PX) yield in 1-hexene aromatization, the effect of the acid properties of HZSM-5 on the distribution of aromatics and the selectivity of PX in the aromatics with a carbon number of 8 (A8) were investigated in this work. The results showed that the aromatics yield and the proportion of A8 in aromatics increased and then decreased when increasing the L/B, reaching the maximum values when L/B was 2.9 (44.2 and 37.9 wt %). When decreasing the external surface Brønsted acid sites (EBA) by chemical liquid deposition (CLD), the aromatics are first increased and then decreased but the selectivity of PX in A8 (PX selectivity) constantly increased. Zn3Si0.75/Z5 with an EBA proportion of 8.6% showed a higher PX selectivity (58.9 vs 24.2%) while maintaining a high aromatics yield (50.5 vs 44.2 wt %), suggesting the existence of a suitable L/B and EBA proportion for the production of PX.