Patent FR-2594139-A1 (FR)
Inventor: JUGUIN BERNARD
IPC: C10L1/06
Filed: 1986-02-13
Abstract: 1. A process for obtaining methyltertiobutylether, a high-grade petrol and a jet fuel from a cut of paraffinic hydrocarbons essentially having 4 carbon atoms per molecule, the process being characterised in that : a) said cut or fresh charge which for the major part comprises a paraffinic C4 cut which has been previously dried, desulphurised and denitrified and which at that stage generally contains for the major part isobutane and n-butane is passed into a vapour phase dehydrogenation zone (7) so as to transform a part at least of the isobutane and n-butane into isobutene, but-1-ene and but-2-enes and buta-1,3-diene, b) the effluent from the dehydrogenation zone which is cooled by heat exchange with said fresh charge is passed into a first fractionating zone (10), at the head of which is collected a gaseous hydrogen-rich mixture containing methane and ethane, said gaseous mixture being recycled for the major part to the dehydrogenation zone (7), and at the bottom of which is collected (conduit (14)) a first product which is passed into a second fractionating zone (15) at the head of which is collected a mixture containing in particular propane and at the bottom of which a second product is collected, c) said second product is treated in the presence of methanol in excess in an etherification zone (18) so as to transform the major part of the isobutene into methyltertiobutylether, d) the effluent from the etherification zone is subjected to at least two fractionating steps in at least two successive fractionating zones (21 and 22), with collection at the bottom of the first fractionating zone (21) through which said effluent from the etherification zone passes, of the excess methanol which is recycled for the major part thereof to the etherification zone (18), with collection at the bottom of the last zone (25) for fractionating the products of the etherification operation of substantially pure methyltertiobutylether and with collection at the head of the last zone (25) for fractionating the products of the etherification operation of a mixture containing isobutane, n-butane, but-1-ene, but-2-enes, buta-1,3-diene and traces of methanol and methyltertiobutylether, the last-mentioned mixture being passed into a unit (28) for washing with acidified water in order to remove methanol and methyltertiobutylether, a water-saturated C4 cut then being taken from the water washing unit and passed into a drying unit (31) to eliminate substantially the whole of the water from said last C4 cut, e) the last C4 cut obtained in step d) is passed into an oligomerisation zone (34) for transforming at least the major part of the n-butenes, but-2-enes and buta-1,3-diene into high-grade petrol and jet fuel, and f) the oligomerisation effluent is passed into at least two successive fractionating zones and a mixture essentially containing isobutane and n-butane is collected at the head of the first fractionating zone (36) through which the oligomerisation effluent passes, the major part at least of said mixture being recycled to the dehydrogenation zone, and a jet fuel-rich cut is collected at the bottom of the last fractionating zone (40) through which the oligomerisation products pass and a high-grade petrol-rich cut is collected at the head of said last fractionating zone (40).