Aromatic Hydrocarbon Production and Catalyst Regeneration in Pyrolysis of Oily Sludge Using ZSM-5 Zeolites as Catalysts

Abstract

ZSM-5 zeolites were selected as catalysts to promote the aromatization during pyrolysis of oily sludge. The total aromatic yield and product distribution were investigated to evaluate the efficiency of the catalysts and the influence of operating condition. The fresh and used catalysts were characterized by means of scanning electron microscopy, inductively coupled plasma optical emission spectrometry, X-ray diffraction, and ammonia temperature-programmed desorption. Results show that the highest catalytic activity (93.37%) was achieved with ZSM-5-O [the silicon/aluminum ratio (SAR) is 19] at a retention time of 40 s. The total aromatic yield increases with a longer retention time and higher catalyst dosage. An increase in the SAR value of ZSM-5 zeolites will reduce its acid density and aromatization activity. The coke deposition leading to deactivation for zeolites was observed, and calcination was used to regenerate the original catalytic performance. After regeneration, crystallinity was not affected b...