Catalyst regeneration process for improving catalyst selectivity

Abstract

The object of the present invention is to provide a catalyst regeneration process which can improve catalyst selectivity. A first aspect of the invention is characterized in that a spent catalyst from a reactor is introduced into a first fluidized bed regenerator and contacted with an oxygen-containing gas stream and optional steam to carry out a coke combustion reaction, wherein the resultant mixture of the partially regenerated catalyst and flue gas is introduced into a second fluidized bed regenerator and contacted with steam and an optional oxygen-containing gas stream to carry out a further regeneration reaction, and then the regenerated catalyst is introduced into the reactor. A second aspect of the invention is characterized in that a spent catalyst from a reactor is introduced into a fluidized dense bed regenerator and contacted with an oxygen-containing gas stream and steam to carry out a coke combustion reaction, and then the regenerated catalyst is introduced into the reactor. The inventive processes result in a more uniform distribution of the regenerated catalyst activity; due to the exposure of the catalyst to a low temperature for a long time, a part of the heavy metals are buried by the matrix and the remaining are passivated. Thereby dry gas and coke yields decrease sharply when hydrocarbons are subjected to a catalytic cracking reaction on the regenerated catalyst.