Boiling range of gasoline

The naphtha fraction is dorninated by saturates having lesser amounts of mono- and diaromatics (Table 2, Eig. 4). Whereas naphtha (ibp to 210°C) covers the boiling range of gasoline, most raw petroleum naphtha molecules have a low octane number and most raw naphtha is processed further, to be combined with other process naphthas and additives to formulate commercial gasoline. 

The structure of the hydrocarbons produced can be modified by the use of catalyst. Catalytic cracking consumes less energy than the noncatalytic process and results in formation of more branch-chain hydrocarbons. On the other hand the addition of the catalyst can be troublesome, and the catalyst accumulates in the residue or coke. There are two ways to contact the melted polymer and catalysts the polymer and catalyst can be mixed first, then melted, or the molten plastics can be fed continuously over a fluidized catalyst bed. The usually employed catalysts are US-Y, and H-ZSM-5. Catalyst activity and product structure have been reported [7-11]. It was found that the H-ZSM-5 and ECC catalysts provided the best possibility to yield hydrocarbons in the boiling range of gasoline. 

Material boiling below 275°C is in the boiling range of gasoline, naphtha, and kerosine. 

Mixtures of 2-methylpentenes and 2,3-dimethylbutenes show good properties as antiknock fuel additives in that they raise the octane number in the low boiling ranges of gasoline. 

The feed for catalytic reforming is mostly in the boiling range of gasoline to start with. The intent is to convert the paraffin and naphthene portions to aromatics. As an example, a 180 to 310°F fraction of Light Arabian crude oil was reported to have 8 vol % aromatics before catalytic reforming, but was 68 vol % aromatics afterwards. The feed paraffin content (69 vol %) was reduced to less than half, and the feed naphthene content... 

The yield of liquid products, including all hydrocarbons in the boiling range of gasoline as well as neohexane, is approximately 70 per cent by weight of the net consumption of ethane-propane and isobutane consumed during decomposition and alkylation. As the normally liquid hydrocarbon content of the coil effluent is increased from 20 to 35 per cent by weight (conversion per pass), the neohexane content of these liquids decreases from about 40 to about 30 per cent. 

The feed used was an FCC gasoline sample obtained from a European refinery and was subsequently distilled to give an approximate boiling range of 35-190°C. 

Remarkable increases in the aromatics content of gasolines and the octane number were obtained with synthetic-aluminum-silicate-supported catalysts (43), as shown in Table XXI. The experiments were made at 250 atm. pressure with petroleum gas oil of 0.846 sp. gr. and a boiling range of 187° to 330°C. Temperatures around 400°C. were used and were adjusted to obtain approximately the same conversion for both catalysts. The silicate catalyst is less active. The high aromatics content obtained with the aluminum silicate catalyst is especially evident in the higher fractions. The amount of branched-chain paraffin hydrocarbons is not greatly different, as shown by the octane number of the aromatic free fractions, used as an index. 

Toluene, Benzene, and BTX Recovery. The composition of aromatics centers on the C - and Cg-fraction, depending somewhat on the boiling range of the feedstock used. Most catalytic reformate is used direcdy in gasoline. That part which is converted to benzene, toluene, and xylenes for commercial sale is separated from the unreacted paraffins and cycloparaffins or naphthenes by liquid—liquid extraction or by extractive distillation. It is impossible to separate commercial purity aromatic products from reformates by distillation only because of the presence of azeotropes, although complicated further by the closeness in boiling points of the aromatics, /o-paraffin, and unreacted C6, C -, and Cg-paraffins. 

The next cut gasoline stream from the crude distillation column is the naphtha cut. This stream has a boiling range of 200-365°F and contains a significant portion of naphthenes, aromatics, and paraffins. Thus, the naphtha cut is hydrotreated and reformed to upgrade this stream into a gasoline blending stock.9... 

In present-day refineries, the fluid catalytic cracking (FCC) unit has become the major gasoline-producing unit. The FCC s major purpose is to upgrade heavy fractions, that is, gas oil from the atmospheric and vacuum distillation columns and delayed coker, into light products. Atmospheric gas oil has a boiling range of between 650-725°F.9... 

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