IMPROVED METHOD OF DEHYDROGENATING ALKYLAROMATIC HYDROCARBONS FOR SYNTHESIS OF VINYLAROMATIC MONOMERS Russian patent published in 2011 - IPC C07C15/46 C07C7/04 C07C7/09 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing and purifying vinylaromatic monomers, involving: a) feeding a stream consisting of an aromatic hydrocarbon, together with a stream essentially consisting of C₂-C₃ olefin, into an alkylation section; b) feeding reaction products coming from the alkylation section into a first separation section; c) outputting from the first alkylation section a first stream consisting of unreacted aromatic hydrocarbon, which is fed for reuse into the alkylation section, a second stream essentially consisting of monoalkylated aromatic hydrocarbon, a third stream essentially consisting of dialkylated aromatic hydrocarbons, fed into the transalkylation section, and a fourth stream essentially consisting of a mixture of polyalkylated aromatic hydrocarbons; d) feeding the second stream from step (c) into a dehydrogenattion section; e) feeding reaction products coming from the dehydrogenation section into a second separation/purification section, comprising at least one distillation column; f) outputting a stream consisting of a vinylaromatic monomer with purity of over 99.7 wt % from the top part of the said at least one distillation column, characterised by that: after first cooling with return of heat leaving the dehydrogenation step and after washing with spray water, the gas is fed into the cladding of a bundle of pipes of a heat exchanger lying vertically or horizontally, in whose pipes cooling fluid flows, where gas condenses in the heat exchanger; gas is fed from the bottom part of the heat exchanger with liquid obtained through condensation, which flows counterflow and comes out of the heat exchanger completely or partially, as well as from the bottom part of the jacket of the heat exchanger, and which is fed into a second separation/purification section (e); possible gas and uncondensed substances are output from the top part of the jacket of the heat exchanger.

EFFECT: use of the present method reduces formation of deposits and solid body mass inside the condensation system and sometimes inside hydrogen compressors.

15 cl, 1 ex, 1 tbl