Ni deposited on the FCC catalyst could not only destroy the structure of the catalyst, but also deteriorate the product distribution. Almost all the Ni on the catalyst existed in the forms of NiAl₂O₄ and Ni₂SiO₄, which can be reduced by H₂ even below 700 ℃. Here a new Ni-removal procedure, reducing activation by H₂ plus washing by dilute nitric acid was suggested. If the catalyst containing 2.13 wt% Ni was treated only once under appropriate conditions, then more than 50% Ni could be removed, and the micro-activity of the catalyst improved markedly. At high temperature, the Ni species in the bulk of the catalyst moved out to the surface during reducing, but the movement might be limited by equilibriums, so repeat of the treating steps was helpful to Ni-removal.

Key words: FCC catalyst, hydrogen, reduction, dilute nitric acid, nickel removal