Study Notes on Crude Oil and Hydrocarbons

Introduction to Crude Oil

©2014 Institute of Technical Education. All rights reserved.

Objectives

  • At the end of the lesson, learners should be able to:

    1. Explain what is hydrocarbon.

    2. Understand the distillation curve.

    3. Calculate crude gravity.

Introduction

  • This lesson introduces different types of hydrocarbons and the physical properties of crude oil, including:

    • Crude characteristics

    • Distillation curve

    • Crude gravity

Main Menu

  • Crude oil is the raw material of many chemical and polymer products. The characteristics of crude oil attract the physical properties and thus the separation of crude oil is important.

    1. What is Hydrocarbon

    2. Types of Hydrocarbon

    3. Distillation Curve

    4. Crude Gravity

  • Quiz

  • Click each section in sequence to understand the characteristics of crude oil. Start the quiz after completing all sections.

Section 1: What is Crude Oil?

  • Crude oil is a mixture of thousands of different chemical compounds.

  • The compounds are a combination of different types of hydrocarbons.

    • Each hydrocarbon has its own boiling point and physical properties.

Section 1: What is Hydrocarbon?

  • Hydrocarbon: A hydrocarbon compound is a chemical consisting of carbon (C) and hydrogen (H) elements in its structure.

    • Basic structure:

    • [ CnHm ]

Aliphatic Hydrocarbons

  • Alkane: Saturated hydrocarbons with single bonds.

  • Alkene: Unsaturated hydrocarbons with at least one double bond.

  • Alkyne: Unsaturated hydrocarbons with at least one triple bond.

  • Cycloalkane: Saturated hydrocarbons that contain carbon atoms arranged in a ring.

  • Aromatic Hydrocarbons: Contain alternating double bonds, stable under normal conditions, ex. Benzene.

Section 1: Hydrocarbon Details

  • Simple hydrocarbons example:

    • Methane: [ CH_4 ]

  • Complex hydrocarbons example:

    • C60:

  • Minor impurities in crude oil are:

    1. Sulfur (S)

    2. Oxide (O)

  • Both impurities can cause corrosion in chemical processes.

Section 2: Types of Hydrocarbon

  • There are basically four types of hydrocarbons in crude oil:

    1. Saturated Hydrocarbon

    2. Unsaturated Hydrocarbon

    3. Ring (Cyclo) Hydrocarbon

    4. Aromatics

Section 2: Saturated Hydrocarbon

  • Characteristics:

    • All valences are satisfied; each carbon has four attachments.

    • Stable under normal operating conditions.

    • Formula: [ CnH{2n+2} ]

  • Example:

    • Ethane: [ CH3-CH3 ]

Section 2: Unsaturated Hydrocarbon

  • Characteristics:

    • Has double or triple bonds between carbon atoms.

    • Instability allows for chemical reactivity.

    • Good starting material for producing other chemical products.

    • Formula for alkene: [ CnH{2n} ]

    • Formula for alkyne: [ CnH{2n-2} ]

  • Examples:

    • Ethene: [ CH2=CH2 ]

    • Acetylene: [ HC≡CH ]

Section 2: Ring (Cyclo) Hydrocarbon

  • Characteristics:

    • Contains five or more carbons bent to form a ring.

    • Formula: [ CnH{2n} ] (more stable than unsaturated due to the ring structure).

  • Examples:

    • Cyclopentane

    • Cyclohexane

Section 2: Aromatics

  • Characteristics:

    • Contains double bonds in a ring structure, stable under normal conditions.

    • Has a distinct aromatic smell.

    • Formula: [ CnH{2n-6} ]

  • Example:

    • Benzene: [ C6H6 ]

Section 3: Boiling of Water vs. Crude Oil

  • Boiling Point of Water:

    • Starts to boil at 100ºC at 1 atm pressure.

    • The boiling temperature remains constant under unchanged atmospheric pressure.

  • Boiling Point of Crude Oil:

    • Comprises a range of boiling points due to various chemical components in the mixture, differing from water with a single boiling point.

  • Components of Crude Oil and Respective Boiling Points:

    • Liquid petroleum gas: <25°C

    • Petrol (Gasoline): 25-60 °C

    • Naphta: 60-180°C

    • Paraffin: 180-220 °C

    • Diesel: 220-250 °C

    • Fuel Oil: 250-300 °C

    • Lubricating Oil: 300-350 °C

    • Bitumen: >350 °C

Section 3: Boiling Point vs. Carbon Number

  • Each compound has its boiling point related to its carbon number.

    • More carbon = higher boiling point.

  • Examples and the relation of carbon number to boiling point:

    • For [ C3H8 ] boiling point: -42°C

    • For [ C4H{10} ] boiling point: 1°C

    • For [ C{10}H{22} ] boiling point: 174°C

Section 3: Terminology of Boiling Point

  • Initial Boiling Point (IBP): Lowest boiling temperature of the components.

  • Final Boiling Point (FBP): Highest boiling temperature of the components.

Section 3: Boiling Range of Crude Oil

  • The distillation process repeats until the final drop of the heaviest component is boiled off, known as the Final Boiling Point (FBP).

Section 3: Distillation Curve

  • Importance of Distillation Curve:

    • Each crude has a unique distillation curve that helps identify its chemical components.

    • Example of distillation curves for Crude A, Crude B, and Crude C indicate different boiling temperatures and cumulative volume percentages.

Section 3: Use of Distillation Curve

  • Example of determining volume percentage of hydrocarbons based on boiling points:

    • Check % volume C14H30 with boiling points:

    • C14H30: Boiling Point 204°C, % Vol 25%

    • C20H42: Boiling Point 316°C, % Vol 50%

    • Calculate % vol C1 in crude based on the provided information.

Section 4: Density and its Importance

  • Density Definition:

    • Density is the amount of a substance contained within a specific volume.

    • Formula: [ Density = \frac{Mass}{Volume} ]

  • Specific Gravity:

    • The ratio of the density of a substance to the density of water under standard conditions.

Section 4: API Gravity

  • In the oil industry, the measure of gravity referred to as API gravity is calculated using the formula:
    [ API \, Gravity = \frac{141.5}{Specific \, Gravity} - 131.5 ]

  • Example Calculation:

    • Calculate API Gravity if the specific gravity of a compound is 0.85:

    • Answer: 34.97

Section 4: Important Concepts for Gravity

  • Specific Gravity and API Gravity Relationship:

    • Water has a specific gravity of 1 and API gravity of 10.

    • Higher API gravity = lighter chemical components; lower API gravity = heavier hydrocarbons.

  • API gravity is widely used in the oil industry to identify crude oil characteristics.

Quiz Questions

  1. Saturated hydrocarbon is more stable than unsaturated hydrocarbon normally.

    • A) True

    • B) False

  2. Unsaturated hydrocarbon is one of the starting materials for chemical products.

    • A) True

    • B) False

  3. Ring hydrocarbon has the same chemical formula as aromatics.

    • A) True

    • B) False

  4. Ring hydrocarbon and aromatics are more stable than unsaturated hydrocarbon.

    • A) True

    • B) False

  5. There are small amounts of oxide (O) and sulfur in crude oil besides hydrocarbons and carbon.

    • A) True

    • B) False

  6. API Gravity is commonly used in the oil industry.

    • A) True

    • B) False

  7. Which crude is heavier?

    • A) Crude A

    • B) Crude B

  8. A chemical compound has a density of 0.8g/cm³. What is its gravity in API?

    • API =