(378e) Butene Oligomerization within Dividing Wall Column

The promotion of ethanol gasoline in China restricts the use of MTBE (methyl tert-butyl ether). This results in shortage of gasoline with high octane number and changes in the scheme of C4 resource processing. In butene oligomerization process, iso-octene, which is the ideal blend composition of gasoline with high octane number, is synthesized from iso-butene. The remnants which contain iso-butane and n-butene are favorable reactants for alkylation. Due to the high reactivity of the resin catalyst, inhibitor such as TBA (tert-butyl alcohol) is introduced to control the reaction temperature. Then TBA is separated from iso-octene in the inhibitor recovery column and recycled to the reactors. If C4 resource contains few pentane, which is common, a certain amount of distillates contain TBA, pentane, hexene and heptene must be discharged outside the battery limits to balance the concentration of pentane. After renovated to dividing wall column, the inhibitor recovery column manifests better separation performance. The weight concentration of TBA of the side product increases from 45% to 92%, which turns out to be more economic for cycle use. Total mass flow of hexene and heptene in the side product reduced 81%, which means less high boiling point olefin will be generated to ensure the gasoline endpoint is within the scope of the standard.