Embodiments described herein generally relate to new processes for converting C4 feeds to isobutylene. In an embodiment is provided a process for forming isobutylene that includes hydroisomerizing 1,3-butadiene present in a C4 feed to form a hydroisomerization product effluent comprising isobutylene and 2-butene; and forming an isobutylene feed by separating the isobutylene from the hydroisomerization product effluent. Embodiments of the present disclosure also generally relate to new processes for converting C4 feeds to polyisobutylene. In an embodiment is provided a process that includes hydroisomerizing a C4 feed comprising 1,3-butadiene in a hydroisomerization reactor to form a hydroisomerization product effluent comprising isobutylene and 2-butene; separating the isobutylene from the hydroisomerization product effluent to form a first isobutylene-containing feed; forming a reaction mixture comprising a polymerization catalyst and the first isobutylene-containing feed; and reacting the reaction mixture, in a polymerization reactor, to form a polymerization product effluent comprising polyisobutylene.

A process for producing para-xylene (PX) comprises supplying a hydrocarbon feed comprising xylenes and ethylbenzene (EB) to a PX recovery unit, where a PX-rich stream and at least one PX-depleted stream are recovered from the feed. The PX-depleted stream is then separated into an EB-rich stream and an EB-depleted stream in a divided wall column. The EB-depleted stream is then isomerized under at least partial liquid phase conditions to produce a first isomerized stream having a higher PX concentration than the PX-depleted stream, and the EB-rich stream is isomerized under at least partial vapor phase conditions to produce a second isomerized stream having a higher PX concentration than the PX-depleted stream. The first and second isomerized streams are then recycled to the PX recovery unit to recover additional PX and the process is repeated to define a so-called xylene isomerization loop.

The present invention is an improved process and apparatus for producing para-xylene, particularly with respect to a process that involves the methylation of toluene and/or benzene to selectively produce para-xylene, wherein streams having differing amounts of ethylbenzene are separately treated in the recovery of para-xylene. A first hydrocarbon feed comprising xylenes and ethylbenzene is provided to a first para-xylene adsorption section, and a second hydrocarbon feed comprising xylenes and less EB than the first hydrocarbon feed is provided to a second para-xylene adsorption section. Segregating the feeds with differing ethylbenzene contents increases the overall efficiency of the adsorption of para-xylene by the adsorption units. Efficiency and energy savings may be further improved by subjecting the lower-content ethylbenzene stream to liquid phase isomerization.