Liquid adsorption process to produce an ultra pure product

Abstract

A process for the etherification and separation of C.sub.3 -C.sub.5 hydrocarbons is improved by the advantageous integration of an oxygenate recovery unit having a 3-bed arrangement into the etherification separation section. A feedstream including C.sub.3 hydrocarbons and isobutene are reacted with methanol in an etherification to produce an etherification effluent that is separated in a first separator into a bottoms stream of MTBE product and an overhead stream of unreacted isobutane, methanol, other oxygenate compounds and C.sub.3 -hydrocarbons. After recovery of methanol, in an adsorptive separation process, the methanol deficient overhead stream enters a second separation zone in the form of depropanizer for the separation of isobutane and higher boiling hydrocarbons from the C.sub.3 hydrocarbons. Any oxygenate compounds that are carried from the bottom of the column with the C.sub.4 + hydrocarbon stream are removed in an oxygenate recovery unit designed to produce an ultra pure product essentially free of oxygenates. A portion of the purified hydrocarbons from the oxygenate recovery unit are recycled as regenerant through the oxygenate recovery unit to desorb oxygenate compounds. This integration of the oxygenate recovery unit provides a closed loop for its regeneration that utilizes existing separation facilities for the removal of oxygenate compounds from the hydrocarbons of the regenerant stream.