Process for the fluidized-bed catalytic cracking of a weakly coking feedstock having a Conradson carbon residue equal to or less than 0.1% by weight and a hydrogen content equal to or greater than 12.7% by weight, comprising at least a step of cracking the feedstock, a step of separating/stripping the effluents from the coked catalyst particles and a step of regenerating said particles, the process being characterized in that at least one coking, carbonaceous and/or hydrocarbonaceous effluent having a content of aromatic compounds of greater than 50% by weight, comprising more than 20% by weight of polyaromatic compounds, is recycled to homogeneously distributed and weakly coked catalyst, before regeneration, in order to adjust the delta coke of the process.

Process for the fluidized-bed catalytic cracking of a weakly coking feedstock having a Conradson carbon residue equal to or less than 0.1% by weight and a hydrogen content equal to or greater than 12.7% by weight, comprising at least a step of cracking the feedstock, a step of separating/stripping the effluents from the coked catalyst particles and a step of regenerating said particles, the process being characterized in that at least one coking, carbonaceous and/or hydrocarbonaceous effluent having a content of aromatic compounds of greater than 50% by weight, comprising more than 20% by weight of polyaromatic compounds, is recycled to homogeneously distributed and weakly coked catalyst, before regeneration, in order to adjust the delta coke of the process.

A process for producing lower olefins from oxygenates includes the steps of contacting a feedstock comprising oxygenates with molecular sieve catalyst in fluidized bed reaction zone under effective conditions, to produce product including ethylene and/or propylene; the effective conditions include that in the fluidized bed reaction zone, the weights of catalysts having various carbon deposition amounts are controlled, calculated as the weight of the molecular sieve in the catalysts, to have the following proportions based on the total weight of the catalysts in the fluidized bed reaction zone: the proportion of the weight of the catalyst having a coke deposition amount of less than 3 wt % is 1-20 wt %; the catalyst having a coke deposition amount of from 3 wt % to less than 5 wt % represents 10 to 70 wt %; and the catalyst having a coke deposition amount from 5 wt % to 10 wt % represents 10 to 88 wt %.