FIELD: chemistry.
SUBSTANCE: method involves: a. continuously feeding benzene and a mixture containing paraffin and olefin into at least one alkylation zone under alkylation conditions, involving presence of an amount of an alkylation catalyst sufficient for catalysis, to obtain an alkylation product containing alkyl benzene, dialkyl benzenes and unreacted benzene; the alkylation catalyst is selected from a group consisting of zeolites, acidified refractory oxides and mixtures thereof. Then b. separating benzene from the alkylation product to obtain a fraction rich in benzene, at least a portion of which is taken for recycling at step (a) and a fraction containing alkyl benzene, paraffin and dialkyl benzene, and essentially not containing benzene. Further c. separating paraffin from said fraction essentially not containing benzene to obtain a fraction rich in paraffin and a fraction containing alkyl benzene and dialkyl benzene and essentially not containing paraffin. Further d. separating alkyl benzene from said fraction not containing paraffin to obtain an alkyl benzene fraction and a fraction of heavy hydrocarbons containing dialkyl benzenes. Then e. feeding benzene and at least a portion of the fraction of heavy hydrocarbons into at least one transalkylation zone, where molar ratio of benzene and dialkyl benzene is at least equal to 20:1, preferably from 30:1 to 60:1. Further f. keeping said at least one transalkylation zone under transalkylation conditions, involving an amount of a solid transalkylation catalyst efficient for catalysis, for obtaining a transalkylation product in which at least 20 mol % dialkyl benzene in the portion of material fed into said reaction zone is converted to alkyl benzene. Further g. fractionation of at least a portion of the transalkylation product to obtain a low-boiling point fraction rich in benzene, and a high-boiling point fraction containing alkyl-substituted benzene. Then h. feeding at least a portion of the fraction rich in benzene into at least one transalkylation zone as at least a portion of benzene for said reaction zone; and i. feeding at least a portion of the high-boiling point fraction from step (g) to step (b).
EFFECT: use of the present method enables to efficiently maintain high molar ratio of benzene and dialkyl benzene in order to increase catalyst stability.
10 cl, 3 dwg
