Light straight-run

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°C, while it is about 80-200°C for heavy straight-run naphtha (HSR). ... 

Light straight-run gasoline After desulfurization, this stream is used in gasoline blending or as isomerization feedstock... 

Light straight-run gasoline Composed primarily of components >C5with a cut point typically between 180°F to 200°F (82.2°C to 93.3°C). It is separated from heavy straight-run gasoline and is caustic washed, hydrotreated, or sweetened the octane number is sometimes improved through isomerization. 

Another application of the Platforming process has been to produce aromatic hydrocarbons. Of particular interest is the production of benzene. It has been shown (10) that yields up to 92% of theoretical based on methylcyclopentane and cyclohexane content can be obtained from light straight-run fractions. Similarly, toluene and xylenes are produced in high yields from the corresponding C7 and Cg fractions. 

A light straight-run fraction, consisting primarily of C5 and C hydrocarbons. These also will contain any C4 and lighter gaseous hydrocarbons that are dissolved in the crude. 

Isomerization of n-paraffins in the C5-C6 range, such as those present in the LSR (light straight run) fraction, is industrially carried out to improve the octane number of the gasoline. Skeletal isomerization of n-paraffins is an acid-catalyzed reaction that is thermodynamically favored at lower temperatures. Therefore, acid catalysts with strong acidity have to be used in order to perform the reaction at temperatures as low as possible. The process is carried out in the presence of hydrogen and a bifunctional catalyst, which typically consists of a noble metal (Pt) supported on an acidic carrier. 

Isomerization increases the octane value of light straight run naphtha by rearranging the low octane straight chain C5-C6 paraffins into their higher octane branched isomers as shown in Table 7.2. 

The reaction of different C3- and C -hydrocarbons and a light straight run (LSR) on a Ga/H-ZSM-5 zeolite and the reaction of propane on a Beta-zeolite, with or without gallium,has been studied. The differences observed in the activity and selectivity are explained taking into account the relative stability of the different possible carbocation intermediates. The influence of the zeolite structure is also discussed. 

Each scheme generates different yield and octane results. The examples given below are for a light straight-run (LSR) process stream, but could also be applied to a reformate stream or some LSR/reformate combinations. In a once-through isomerization process scheme, the LSR is mixed with the hydrogen makeup gas the mixture is then heated and enters a first reactor where benzene saturation and partial isomerization take place. 

Hydrotreated light petroleum distillates. See Petroleum distillates, hydrotreated light Hydrotreated light straight run petroluem. See Naphtha, hydrotreated light Hydrotreated middle distillate Hydrotreated middle petroleum distillate. See Petroleum distillates, hydrotreated middle Hydrotreated (mild) heavy naphthenic distillate. See Petroleum distillates, heavy hydrotreated naphthenic... 

The deisopentanizer (DIP) tower, shown in Figure 14.8, processes light straight-run naphtha from two sources. The debutanizer bottoms consists of primarily iso and normal pentane (iCs and Cs), with small fractions of butane and Cg-I- components. The overhead from the naphtha fractionator tower contains mostly C5 and Ce paraffin compounds, with some benzene and Ce naphthenes and a small amount of butane. The combined feed to the DIP is typically in the range of 9,000-15,000 bpd. 

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