A study of acidity and coke deposits om NiHZSM-5 catalyst in aromatization

The acidity and coke deposits of HZSM-5 and NiHZSM-5 catalysts were studied in the aromatization using NH3-TPD, IR and TPD techniques. The results sho wed that both strong acid and B acid sites decreased quickly at the initial stage of reaction for the two catalysts. The coking and reaction rates als o dropped quickly at this stage. Yet it was discovered that adding Ni into HZSM-5 led to weakening B acid sites and strengthening L acid ones. At the same time, the results revealed that metallic Ni decreases the coking rates and slows down the activity decline rates.