Study On Preparation And Reaction Performance Of High Activity Additive In FCC

As crude oil gets heaver and its quality becomes worse, fluid catalytic cracking units which just process the traditional vacuum gas oil can not qualify for processing the present raw materials. Thus, FCC has been developed for cracking residual oil resources, or in other words, for meeting the need of yearly increase of residua blending ratio. For this purpose many countries have paid much attention to the research and development (R&D) in FCC technology for processing partial or all residue oil. The R&D focuses on how to increase the capacity of heavy oil processing and light oil yield, which is also the topic of this thesis.Firstly, FCC mechanism was summarized and analyzed in this paper. The research advances in RFCC technology for increasing light oil yield were discussed and the progress in bottom cracking additives was summed up. The conclusion is that domestic research on this respect is still at the beginning stage. And a novel preparation technique of the catalytic cracking additive which improves light oil yield and enhances bottom cracking ability was proposed.Secondly, the additive was prepared in the laboratory, and characterized by using the fixed-fluidized bed reactor. The parameters, such as active carrier content, zeolite molecular sieve and its content, were investigated for determining cracking performance and distribution of cracking products. The results show that adding active carrier could optimize the pore structure of the additive, and improve the ability of heavy oil cracking. However, active carrier can't be added too much, or it would reduce the additive strength. In this paper USY and REY zeolite molecular sieves were used as the main active components in the additive, which exhibit high cracking activity. Furthermore, these zeolites chosen as active components have the advantage of higher light oil selectivity and lower coke productivity. Even though the content of zeolite molecular sieve can improve the activity of additive, its amount should be controlled to an appropriate range, otherwise, the coke yield will be significantly increased and the strength of additive will be decreased.