Catalytic cracking of acidified oil and modification of pyrolytic oils from soap stock for the production of a high-quality biofuel

Soap stocks are by-products obtained during the refining process of vegetable oil, and are mainly feedstocks to produce acidified oil. In this work, an efficient process was developed to convert soap stock into a high-quality biofuel with low impurity content. A combination of acidification and catalytic cracking reactions employed as pretreatment was investigated to decrease the impurity content in the soap stock feedstock for obtaining a value-added biofuel. A high olefin content (approximately 47%) pyrolytic oil was obtained during the pretreatment. For further improvement of the cold flow properties, hydro-isomerization of pyrolytic oil for the formation of iso-alkanes over the Ce–Pt/SAPO-11and Ce–Pt/ZSM-5 catalysts was then carried out. The isomerization reaction temperature could be decreased to 320 °C because of the approximately 47% olefin content. The cold filter plugging point (CFPP) of the resulting product could be obtained at −11 °C, and the sulfur content could be decreased to lower than 10 ppm, which could meet the EN and ASTM specifications.