• Naphtha:

    • Naphtha is a generic term normally used in the petroleum refining industry for the overhead liquid fraction obtained from atmospheric distillation units. The approximate boiling range of light straight-run naphtha (LSR) is 35–90\(^\circ\)C, while it is about 80–200\(^\circ\)C for heavy straight-run naphtha (HSR).

      • HSR is usually subjected to cyclisation in reforming units to increase octane number.

      • LSR is processed in naphtha cracker as a feedstock.

    • Atmospheric distillation of the best crudes yields about 60% naphtha plus middle distillates (kerosene and gas oil), but the average is closer to 40%.

    • Naphtha from atmospheric distillation is characterized by an absence of olefinic compounds.

    • Naphtha is also obtained from other refinery processing units such as catalytic cracking, hydrocracking, and coking units. The composition of naphtha, which varies appreciably, depends mainly on the crude type and whether it is obtained from atmospheric distillation or other processing units.

    • Naphthas obtained from cracking units generally contain variable amounts of olefins, higher ratios of aromatics, and branched paraffins. Due to presence of unsaturated compounds, they are less stable than straight-run naphthas.