Study On FCC Gasoline Deep Catalytic Cracking

With the development of world economy, the demands for light olefins and their derivatives increase, and the low olefin content in gasoline is needed, which make more studies on FCC gasoline reprocessing with different methods. In recent years, the study on FCC gasoline mostly focus on upgrading or decreasing the olefins content. And few studies on FCC gasoline deep catalytic cracking under high temperature and short residence time were reported. Therefore the reaction rules of FCC gasoline deep catalytic cracking were studied in this paper.A pulsating reaction system was employed to investigate the fast reactions of FCC gasoline. The reaction rules of FCC gasoline and light gasoline deep catalytic cracking at different conditions, such as temperature, catalyst/oil ratio and residence time, have been studied. And the reactions of FCC gasoline deep catalytic cracking on different types of catalyst and spent catalysts with different coke content have also been studied. The results showed that under the experimental conditions, the reaction characteristics of light gasoline deep catalytic cracking were the same as those of FCC gasoline. In order to obtain more propylene, the temperature should be controlled under 600℃, and high catalyst/oil ratio and suitable residence time should be adopted. With the operating conditions changed, the variations of olefins and aromatics in gasoline were obvious. When the catalyst containing ZSM-5 shape selectivity molecular sieve with high activity was used, the yields of propylene, LPG and dry gas were high. Whereas, when the catalyst containing ZSM-5 with low activity was used, the selectivity of propylene was high. The coke of catalyst whose carbon content was below 1.56% was created on the outer surface of the catalyst, and under the experimental conditions spent catalysts with different coke content had little effect on the reaction properties of gasoline. Owing to the fact that the residence time in mini-scale pulse reactor was short, the reaction properties of FCC gasoline were studied in the confined fluidized bed reactor. The results showed that the reaction properties of FCC gasoline with the above different reactors were similar, but the conversion in the confined fluidized bed reactor was much higher. When diesel oil and coke produced were excluded, the conversion in the confined fluidized bed reactor was higher than that in the mini-scale pulse reactor by 12 percents.