Method for green recovery of rare earth in waste FCC catalyst based on high-concentration aluminum salt system

The invention relates to a method for green recovery of rare earth in a waste FCC (fluid catalytic cracking) catalyst based on a high-concentration aluminum salt system, which is characterized by comprising the following steps: firstly, carrying out two-step reduction leaching on the waste FCC catalyst by adopting a high-concentration aluminum salt solution-hydrogen peroxide system to obtain a leachate containing rare earth lanthanum and cerium; then separating and purifying the rare earth from the rare earth-containing leaching solution through P204 extraction and hydrochloric acid reverse extraction to obtain a rare earth purified solution; finally, a high-purity lanthanum and cerium oxalate mixed product is obtained through oxalic acid precipitation, and green, clean and efficient recovery of rare earth lanthanum and cerium in the waste FCC catalyst is achieved. According to the method, the extraction efficiency of the rare earth in the waste FCC catalyst exceeds 90%, the purity of the recycled product exc