Passivation Element Mobility And New Solid Passivating Agent

The usage of liquid passivators and solid scavangers have been widely adopted for reducing deteriorated effects of metals on FCC. The former dissolved passivation agent in liquid and finally deposited on the catalyst surface during FCC processing. It reacts with metals on catalyst and takes a role of passvition. The latter can trap vanadium owing the mobility of vanadium oxide, which then forms vanadium compounds with higher melting points on the catalyst.The theme of this thesis is to put forward a new idea of developing a solid passivator that can passivate both Ni and V on the polluted catalyst. Under the condition of FCC, deposited Nickle compound on catalyst has no mobility while deposited Vanadium compound has stronger mobility. So it is postulated that an effective dual function solid passivator must contain a substance that has good mobility so that it can transfer to the catalyst surface to passivate the deposited Ni and also contains a substance that has good V205 affinity so that it can absorb V205 which being transferred from polluted catalyst to the solid passivator. The function of this bi-directional transferring process, both V and Ni on cracking catalyst can be passivated.In order to find the effective compounds with good mobility, compounds containing Sb, Ti, Bi, P. Sn, Mg, La, Ce and B have been screened under the simulating FCC conditions. The result shows that compounds containing P, B, Bi and Sb have considerable mobility. Taking antimony compound as a model, further experiments on the effects of temperature , carrying vapor and time on its mobility have been investigated.Base on the mobility studies, effective agents composed of Ml wasselected. Cdrier materials such as Kaoline, Sepiolite, Rectorite and a newmaterial MPA were studied. Finally a solid passivator MPA-Ml wascompounded and tested on Fixed Fluidized Bed pilot unite for itsperformance. The result shows it passivates Ni and V as good as that ofliquid passivator.