Preparation Of New FCC Catalysts And Additives And Regulation Of Catalytic Cracking Products

Global oil refining capacity continues to be surplus,coupled with the popularity of new energy vehicles and the impact of double carbon target,the oil refining industry is bound to transform to refining-chemical integration.FCC is one of the core processes of refining-chemical integration.Using this process to increase the production of low-carbon olefins and other chemicals is a research hotspot.The main work of this paper is to adjust the product distribution on the basis of improving the activity of FCC catalyst,and improve the stability and resistance to heavy metal contamination performance of catalysts.ZSM-5 zeolite is often used as the active component of propylene additives due to its special pore structure.In this paper,ZSM-5 zeolite was modified by three different modification methods and then they were prepared as additives to increasing propylene production.The samples were characterized by XRD,N₂ physical adsorption,NH₃-TPD,Py-IR and were mixed with high activity FCC catalyst for performance evaluation on heavy oil microreactor.Then,the mechanism of ZSM-5 zeolite increasing propylene was explored by using 1,3,5-triisopropylbenzene and diisopropylbenzene as probe molecules.Finally,the stability and heavy metal resistance of the catalysts were evaluated.The results showed that:（1）SM series main catalysts used modified Y zeolite with small size and high framework Si O₂/Al₂O₃ ratio as the active component,which showed the characteristics of high activity and high gasoline yield on the microreactor evaluation of the heavy oil catalytic cracking.Their catalytic cracking activities of heavy oil were higher than that of industrial equilibrium catalyst.The heavy oil conversion rate of SM26 was as high as 94.54%.There was 6%higher than that of industrial equilibrium catalyst.（2）A series of additives PZA,LPZA and PZB were prepared by phosphorus modification or phosphorus and lanthanum modification of ZSM-5 zeolite.The additives were added into main catalysts with the proportion of 5wt%for microreactor evaluation.Among PZA series,when the additive modified with 9%P,it showed the best performance.The conversion rate of heavy oil was 91.66%,with a gasoline yield of 53.44%and a propylene yield of 7.99%.The selectivity of propylene in LPG reached 42.27%.Among LPZA series,when the additive modified with 7%P and 3%La,the conversion rate of heavy oil reached 93.01%,with a gasoline yield of 56.28%and a propylene yield of 7.09%.The selectivity of propylene in LPG was 40.83%.Among PZB series,when the additive modified with 7%P,the conversion rate of heavy oil was 90.21%,with a gasoline yield of 51.84%and a propylene yield of 7.78%.The selectivity of propylene in LPG was 40.48%.（3）For the cracking of 1,3,5-triisopropylbenzene,the reaction over the additives mainly represented one-time cracking,while that over the main FCC catalyst represented secondary cracking and tertiary cracking.When p-diisopropylbenzene and m-diisopropylbenzene are used as probe molecules,p-diisopropylbenzene was easier to be cracked due to the smaller molecular dynamics diameter.（4）Compared with nickel,vanadium can poison the catalyst more.Under the same amount of contamination,the activities of vanadium contaminated catalysts decreased more obviously.After adding vanadium collector,the gasoline yield increased.The biggest problem of nickel is its high dehydrogenation activity.When the nickel contamination was 6000 ppm,the amount of hydrogen increased six times.After adding P-modified macroporous alumina as nickel collectors,the amount of hydrogen decreased by half.Nickel collectors had a certain ability to resist nickel contamination.