Carbon Chemistry - Fractional Distillation Flashcards
What is crude oil?
Crude is a mixture of hydrocarbons of various carbon-chain lengths.
What property of hydrocarbons allow fractional distillation to take place?
The different boiling points.
Shorter chains have lower boiling points
Longer chains have higher boiling points
What is crude oil separated into?
Useful parts (fractions) that contain hydrocarbons of similar boiling points and carbon chain lengths.
How does a fractional distillation column work?
-Hot crude oil is added to the bottom of the column. A TEMPERATURE GRADIENT exists in the column, so it’s hotter at the bottom than at the top.
- Hydrocarbons with low boiling points evaporate and rise to the top of the column where they are collected as a gas.
- Hydrocarbons with higher boiling points condense at various layers throughout the column and are collected as liquids.
- Those with really high boiling points are collected towards the very bottom of the column
- bubble caps help to condense
-The fractions can then be separated further using more specific distillation methods
Why isn’t crude oil very useful?
because it is
- difficult to handle
- viscous
- hard to ignite
- contains many high value products that can only be used once they have been extracted
- viscous
The gradients in a fractional distillation tower (6)
- Gases (1-4 C) Used as fuels for heating, cooking, and manufacture of PLASTICS eg methane, ethene
- Gasoline (5-12C) Used as fuels for vehicles, LPG, various petrochemicals and solvents eg octane. VOLATILE
- Light Distillates (12-16 C) Used as aviation fuel, naphthas, solvents, kerosene and refined oils
- Intermediate distillates (15-18) Used as diesel fuel and heavy fuel for oil for ships and power stations
- Heavy distillates (16-20) Used as lubricating oils, wax, grease and petrochemicals
- Residues (>20) Used as bitumen for roads, asphalt and petroleum jelly.
