Reformation of petroleum – All four types of reactions

Reformation

It is a process of bringing structural modifications in the strait chain hydrocarbons (with lower octane number) to increase the octane number and thereby improving the anti-knocking characteristics of petrol. It’s a process of upgrading the octane number of petrol fraction is called as reformation. By reformation high-octane petrol is obtained. If the Reformation of petroleum is done using a catalyst it is called as catalytic reformation.
The process involves a molecular rearrangement of hydrocarbons with out any change in the no of carbon atoms to form new compounds.

Conditions:
Feed stock: Low grade petrol
Temp: 470- 550{o}_C
Pr: 10- 25 atm pr
Catalyst: Pt

Octane number’s defined as the percentage of isooctane present in a standard mixture of isooctane and n-heptane, which knocks at the same compression ratio as the petrol being tested.
Isooctane is the branched chain hydrocarbon has least knocking rate, hence its octane number is arbitrarily fixed as 100. N-heptane a straight chain hydrocarbon has highest tendency to knock hence its octane number’s fixed as zero. Octane number of petrol is 80 means it contains 80% by volume isooctane and 20% by volume n- heptane.

Reforming is a chemical process, which involves modification of the structure of molecules without much change in the molecular masses. Reformation of petroleum involves the following reforming reactions:
1) Isomerisation.
2) Dehydrogenation.
3) Cyclisation & dehydrogenation and
4) Hydro cracking.

1) Isomerisation: – It is a process of converting the straight chain hydrocarbon compound of lower octane number into a branched chain hydrocarbon compound of higher octane number.

Reformation of petroleum - Isomerisation

2) Dehydrogenation: It is process in which the H2 is removed producing a aromatic molecule.

Reformation of petroleum - Dehydrogenation

3) Cyclization and dehydrogenation: Straight chain hydrocarbons undergo cyclisation to form cyclic compounds, which further undergoes dehydrogenation to form aromatic compounds.

Reformation of petroleum - Cyclization and dehydrogenation
Reformation of petroleum - Cyclization and dehydrogenation

4) Hydro cracking: -Straight chain hydrocarbons undergo hydro cracking in presence of hydrogen and platinum catalyst producing low molecular weight gaseous fractions which are removed to improve the octane number.

Hydro cracking

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