ISOPRENE PRODUCTION PROCESS Russian patent published in 2007 - IPC C07C11/18 

FIELD: petrochemical processes.

SUBSTANCE: isoprene is obtained from isobutylene-containing stream and formaldehyde. Process comprises at least zones for chemical conversion in presence of strong-acid catalyst(s) and water and zone(s) for separating resulting mixtures. At least one of zones is used to carry out liquid-phase synthesis of intermediates suitable to be converted into isoprene, in which process unconverted C₄-hydrocarbons are preferably separated and stream containing these intermediates are subjected to joint processing in vertical intermediate conversion zone(s) to produce isoprene preferably at ascending travel of stream(s). Converted vapor stream picked from the top of the conversion zone chiefly contains isoprene and isobutylene, and partially water. The stream is separated to remove at least one liquid stream containing chiefly water and optionally acid and organic impurities. This stream freed of high-boiling by-products (capable of being densified) is recycled to synthesis zone(s) and/or intermediate conversion zone(s). Resulting liquid organic stream contains high-boiling by-products, major part of which are separated inside intermediate conversion zone(s) and/or in a separate outer zone by way of extraction at 65 to 170^°C with organic solvent containing essentially no alkadienes and components forming azeotropes with isoprene, which solvent is unable of forming homogeneous mixture with the above stream supplied in amount large enough to extract most part of high-boiling by-products. After extraction and settling, low layer is recycled to intermediate conversion zone(s) and optionally partially to intermediate synthesis zone(s).

EFFECT: alleviated clogging of equipment and reduced power consumption.

14 cl, 1 dwg, 7 ex