A processing unit includes a naphtha hydrotreating unit comprising a first divided wall column, a naphtha splitter system, and a deisopentanizer column coupled to an output of a naphtha splitter of the naphtha splitter system, an isomerization unit coupled to an outlet of the deisopentanizer column, and a second divided wall column. The processing unit also includes an isomerization reactor coupled between the deisopentanizer column and the stabilizer column.