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

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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)

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

Name	Atoms and Bonds	Stick Representation
Cyclohexane (6 C atoms)

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