IMMOBILIZATION OF METAL CONTAMINANT OF HYDROCARBON CRACKING CATALYST BY INJECTION OF RARE EARTH ELEMENT AND/OR YTTRIUMINCHARGED SUBSTANCE

摘要

Process for passivation of metal contaminants in which the following are brought into contact under cracking conditions: a) a hydrocarbon feedstock containing at least 1 ppm by weight of metal contaminants, b) a cracking catalyst based on a zeolite. This process is characterised by the continuous or periodic introduction into the hydrocarbon feedstock of at least one passivating agent comprising at least one compound of metal M chosen from the group consisting of carboxylates and complexes with polyketonic compounds, polyaminopolycarboxylic compounds and nitrilotricarboxylic compounds, the said metal M being chosen from the group consisting of rare-earth metals and yttrium and the said compound being introduced into the feedstock in the form of a solution in a part of the said feedstock, of a solution in an organic solvent S or of an emulsion in a water-organic solvent S mixture, the said organic solvent S being chosen from organic solvents which are at least partly miscible with the said hydrocarbon feedstock. The process applies in particular to feedstocks containing vanadium V and a quantity of passivating agent such that the atomic ratio M/V is from 0.05:1 to 100:1 is preferably added.