FCC轻汽油催化裂化生产丙烯反应规律的研究

FCC light gasoline containing great lot olefins is a kind of good catalytic cracking feedstock for propylene production. A series of experiments about catalytic cracking of light gasoline and 2M1C5＝were carried out with the ZSM-5 catalyst under different conditions on the riser experimental unit and the subminiature reactorchromatograph united apparatus. Results show that the contents of C5＝ and C6＝ in FCC gasoline can be enhanced via using the ZSM-5 catalyst in catalytic cracking. Light gasoline is more suitable for producing propylene than heavy gasoline or full fraction gasoline. High propylene yield can be obtained from light gasoline even when reaction temperature is low and the contact time is only several milliseconds. The effects of temperature and flow velocity of N2 on propylene yields of cracking light gasoline and 2M1C5＝are nearly the same, namely propylene yield increases when temperature increases or flow velocity of N2 decreases. The ratio of propylene to butenes can rise via increasing temperature and prolonging contact time. The coking rate of the ZSM-5 catalyst is rapid at beginning and afterwards slow gradually. There is a greater influence of the coking of ZSM-5 catalyst on propylene yield than on butenes yield. It is beneficial to increase propylene yield when there are more strong sites on ZSM-5 zeolite.