Interactons between heavy metals and clay matrix in fluid catalytic cracking catalysts

摘要

The interactions between heavy metals (vanadium and nickel) and kaolin had been investigated by X-ray diffraction and MAT test.In the process of pharse transformation of kaolin contaiing 1-5% vanaium,vanadium-mullite phase emerged surprisingy at 660-700 deg C.The unit cell size of the mullite was found to increase with increment of vanadium content.As compared with hydro-kaolin,acid-modified kaolin (AMK) and caustic-modified kaolin (CMK) reacted with vanadium to form much more mullite;CMK could even be reacted with nickel to form a rather stable NiAl_10O_16 compound,and this compound protected zeolite in fluid catalytic cracking catalyst effectively.The catalyst containing AMK had greater MAT activity retention than that of the contrastive catalyst wieh hydro-kaolin in the identical level of heavy metal contamination.