Process for removing isobutene from a C4 cut and producing methyl tert-butyl ether

Claim 1

A process for producing methyl tert-butyl ether and recovering a substantially isobutene- and methanol-free C 4 cut by reacting methanol with a hydrocarbon C 4 cut comprising from 10 to 60% by weight of isobutene, said process comprising the steps of: (a) contacting a mixture of methanol, said C 4 cut, and a recycle stream as hereinafter defined, in a first reaction zone, with an acid catalyst, under conditions for etherification of isobutene with methanol, and converting from 93 to 98% of isobutene, the methanol/isobutene molar ratio being maintained higher than 1:1 at the inlet and at the outlet of said first reaction zone; (b) fractionating the effluent from step (a) under a pressure of at least 10 bars, and separately recovering an overhead fraction having a methanol/isobutene molar ratio higher than 1:1 and a bottoms product fraction comprising methyl tert-butyl ether, and discharging said bottoms product fraction; (c) contacting the overhead fraction from step (b) with an acid catalyst, in a second reaction zone, under conditions for etherification of isobutene with methanol such that an overall isobutene conversion of at least 99% is effected; (d) fractionating the effluent from step (c) under a pressure of 1-9 bars, and separately recovering an overhead fraction consisting essentially of C 4 hydrocarbons and a minor proportion of methanol, and a bottoms fraction containing methanol, methyl tert-butyl ether and a minor proportion of C 4 hydrocarbons, and having a methanol/methyl tert-butyl ether molar ratio higher than 1:1, said bottoms fraction being recycled as said recycle stream to step (a); and (e) washing at least a portion of the overhead fraction from step (d) with water, and separately recovering a substantially isobutene- and methanol-free C 4 cut, and a methanol-containing aqueous wash stream.