Petroleum, as obtained from the oil wells, is predominantly a mixture of many hydrocarbons with differing molecules structure. It also contains a small amount of sulphur, oxygen, nitrogen and impurities such as water and sand.
The carbon-hydrogen atoms may be linked in different ways in a hydrocarbon molecule and this linking influences the chemical and physical property of different hydrocarbon groups. Most petroleum fuels tend to exhibit the characteristics of that type of hydrocarbon which forms a major constituent of the fuel.
The carbon and hydrogen combine in different proportions and molecular structure to form a variety of hydrocarbons. The carbon to hydrogen ratio which is one of the important parameters and their nature of bonding determine the energy characteristics of the hydrocarbon fuels. Depending upon the number of carbon and hydrogen atoms the petroleum product is classified into different groups.
The differences in physical and chemical properties between different types of hydrocarbon depend on the chemical composition and affect mainly the combustion process and hence, the proportion of fuel and air required in the engine. The basic families of hydrocarbons, their general formula and their molecular arrangement are shown below :
1. Paraffin :
The carbon-hydrogen atoms may be linked in different ways in a hydrocarbon molecule and this linking influences the chemical and physical property of different hydrocarbon groups. Most petroleum fuels tend to exhibit the characteristics of that type of hydrocarbon which forms a major constituent of the fuel.
The carbon and hydrogen combine in different proportions and molecular structure to form a variety of hydrocarbons. The carbon to hydrogen ratio which is one of the important parameters and their nature of bonding determine the energy characteristics of the hydrocarbon fuels. Depending upon the number of carbon and hydrogen atoms the petroleum product is classified into different groups.
The differences in physical and chemical properties between different types of hydrocarbon depend on the chemical composition and affect mainly the combustion process and hence, the proportion of fuel and air required in the engine. The basic families of hydrocarbons, their general formula and their molecular arrangement are shown below :
1. Paraffin :
- General formula: CnH2n+2
- Molecular structure: Chain
- Saturated / Unsaturated : Saturated
- Stability: Stable
2. Olefin :
- General formula: CnH2n
- Molecular structure: Chain
- Saturated / Unsaturated : Unsaturated
- Stability: Unstable
3. Naphthene :
- General formula: CnH2n
- Molecular structure: Ring
- Saturated /Unsaturated: Highly saturated
- Stability: Most stable
4. Aromatic :
- General formula: CnH2n-6
- Molecular structure: Ring
- Saturated / Unsaturated : Unsaturated
- Stability: Unstable