METHOD FOR PRETREATMENT IN METATHESIS APPARATUS WITH FORMATION OF OCTENE Russian patent published in 2012 - IPC C07C6/04 C07C2/08 C07C11/06 C07C11/02 B01J8/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of converting a stream of C₄ olefins containing isobutene, but-1-ene and butadiene to propylene and octenes. The method involves a) selective hydrogenation of the stream of C₄ olefins in the presence of a catalyst to remove butadiene via partial hydrogenation to butenes, and converting but-1-ene to but-2-ene to obtain a partially hydrogenated effluent; b) separating the partially hydrogenated effluent through distillation into a head fraction containing but-1-ene and hydrocarbon compounds which boil at a lower temperature than but-1-ene, and a bottom fraction containing compounds which boil at a higher temperature than but-1-ene; c) feeding at least a portion of the head fraction from step (b) as dimerisation material into a dimerisation reactor, wherein the dimerisation material undergoes dimerisation in the presence of a dimerisation catalyst to form a dimerisation reaction product; d) separating at least a portion of the dimerisation reaction product to form a liquid stream rich in octene and a vapour stream rich in C₄; e) feeding the octene-rich liquid stream from step (d) to distillation step (b) and removing the bottom product from the distillation step (b) which contains almost all octene from the liquid stream rich in octene; f) removing a middle fraction product containing but-2-ene from the distillation step (b) from an intermediate point between points where the head and bottom fractions are extracted; and g) the middle fraction product undergoes metathesis with ethylene in the presence of a metathesis catalyst to obtain a metathesis reaction product containing propylene. The invention also relates to an apparatus realising said method.

EFFECT: use of the present invention reduces capital and operating costs and improves characteristics of the metathesis material.

10 cl, 1 dwg