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8.1: Review of Refinery Processing and Chemical Structures for Jet Fuel and Diesel Fuel

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    48592
  • 8.1 Review of Refinery Processing and Chemical Structures for Jet Fuel and Diesel Fuel

    Recall from Lesson 2 the general schematic of a refinery, shown here in Figure 8.1. Jet fuel is typically in the middle distillate range, also known as naphtha and kerosene. Diesel fuel is heavier (higher molecular weight and longer long-chain hydrocarbons). These fuels do not require as much processing because they can be obtained primarily from distillation of oil, but because of sulfur/oxygen/nitrogen functional groups and high molecular weight waxes, these fuels must have these components removed. They are hydrotreated (hydrogen is added, sulfur/oxygen/nitrogen are removed, and aromatics are made into cycloalkanes). Waxes are also separated out.

    Primary processes that are typical in a petroleum refinery see text description below
    Figure 8.1: Primary processes that are typical in a petroleum refinery.

    Click here for a text alternative of Figure 8.1

    This is a simple flow diagram of crude oil refinery.

    Crude oil enters and goes to distillation.

    From distillation:

    LPG (gases) goes through alkylation to become O.N. 100 Motor Fuel Alkylate which can go one to become gasoline

    Straight-run gasoline goes through catalytic reforming to become O.N. 95 Reformate which can go on to become gasoline

    Naphtha, Kerosene and Diesel all go through Hydrotreating and then dewaxing to become either treated Kerosene, Diesel (low sulfur) or lubricating oils.

    Fuel Oil goes through a catalytic cracker to become O/N 90-95 Gasoline

    Resid goes through Thermal Cracking to become either Carbon, Asphalt or O.N. 75 Gasoline.

    Credit: Dr. Caroline B. Clifford

    The primary structure we want for jet fuel and diesel fuel is:

    Alkane - atoms are lined up. For stick representation, each corner represents a CH2 group, and each end represents a CH3 group.

    Name Atoms and Bonds Stick Representation
    Heptane (7 C atoms) 7 Cs connected in a line with 3Hs on each terminal C and 2 Hs on each middle C zigzag with 7 corners including the ends

    Cycloalkanes - again, still an alkane, but forms a ring compound.

    Name Atoms and Bonds Stick Representation
    Cyclohexane (6 C atoms) hexagon with CH2 on each vertice hexagon

    Table 8.1 also shows a list of different chemicals and the properties of each. This table is mainly focused on those chemicals that would be in jet and diesel fuels.

    Table 8.1: List of common hydrocarbons and properties

    Name Number of C Atoms Molecular formula bp (0C), 1 atm mp (0C) Density (g/mL)(@200C)
    Decane 10 C10H22 174.1 -30 0.760
    Tetradecane 14 C14H30 253.5 6 0.763
    Hexadecane 16 C16H34 287 18 0.770
    Heptadecane 17 C17H36 303 22 0.778
    Eicosane 20 C20H42 343 36.8 0.789
    Cyclohexane 6 C6H12 81 6.5 0.779
    Cyclopentane 5 C5H10 49 -94 0.751
    Benzene 6 C6H6 80.1 5.5 0.877
    Naphthalene 10 C10H8 218 80 1.140
    Tetrahydronaphthalene(tetralin) 10 C10H12 207 -35.8 0.970
    Decahydronaphthalene(decalin) 10 C10H18 187,196 -30.4, -42.9 0.896
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