METHOD FOR CATALYTIC CRACKING WITH FAST FLUIDISATION TO OBTAIN LIGHT OLEFINS FROM HYDROCARBON STARTING MATERIAL

FIELD: chemistry. ^ SUBSTANCE: method for synthesis of light olefins via catalytic cracking involves: (a) feeding starting material, naphtha or kerosene, and diluted vapour or carrier gas into a reactor with an ascending packed catalyst bed in which the flow mode is a fast fluidisation mode so as to induce a catalytic cracking reaction in the presence of a catalyst; (b) separation of the catalytic cracking effluent into a catalyst and a reaction product containing ethylene and propylene; (c) cleaning the catalyst separated at step (b) in order to remove a hydrocarbon compound contained in said catalyst; (d) mixing the catalyst cleaned at step (c), with an oxygen-containing gas which contains air so as to continuously regenerate the catalyst; (e) circulating the catalyst regenerated at step (d) to step (a) so as to repeatedly feed it into the reactor with an ascending packed catalyst bed; and (f) cooling, compressing and extracting the hydrocarbon compound extracted at step (b) as the reaction product, that way obtaining a light olefin product, wherein in the fast fluidisation mode is realised by maintaining a normal mode in which the catalyst is continuously fed in a predetermined amount into the reactor with an ascending packed catalyst bed, while the speed of the gas stream into the said reactor is kept higher than in a turbulent mode and lower than in a mode of pneumatic transportation of the catalyst suspended in the gas stream, and in such a flow mode a portion of the catalyst volume varies on the entire height of the reactor with an ascending packed catalyst bed and there is a dense area in the bottom part of the said reactor, and a diluted area in its top part, where in the fast fluidisation mode i) the catalyst is continuously fed into the bottom part of the reactor with an ascending packed catalyst bed, while the speed of the gas is kept lower than the speed of the gas stream required for efficient removal of the catalyst from the bottom part of the said reactor by carrying away; and ii) the difference between portions of the catalyst volume at 1/4 level and 3/4 level from the bottom part of the said reactor falls since the speed of the gas stream increases under conditions i) such that the difference between them is equal to or greater than 0.02, by controlling speed of the gas stream and rate of feeding the catalyst, wherein the catalyst has average size of 20-200 mcm. ^ EFFECT: efficient mode for selective synthesis of ethylene and propylene. ^