Chemistry tips

Cetane Number
Cetane Number is used to determine quality of diesel. It is the percentage byvolume of cetane in a mixture of cetane(spontaneous ignition , cetane number= 100) and α -methyl naphthalene (slow ignition , centane number = 0) which has the same knocking performance as the fuel under consideration.
CRACKING
It is the conversion of less valuable higher fraction to the more valuable lower fraction by the application of heat.
REFORMING (AROMATISATION)
It is the process of converting straight chain hydrocarbon into aromatic compound.
*. Both cracking and reforming are used to increase the quality of petrol , diesel and kerosene.
*. Cracking can be vapour phase , thermal cracking or catalytic cracking.
*. Reforming or aromatisation or platforming is the process of converting straight chain hydrocarboninto aromatic compound.
*. In reforming antiknock properties increases by special types of cracking which includes alkylation , isomerisation , aromatisation , cyclisation , dehydrogenation , fractionation etc
Sythetic Petrol
Bergius Process
Fisher - Tropsch process
In this process steam is passed over red hot coke to get water gas, which is a mixture of CO and H 2 .
The water gas is mixed with half its volume of hydrogen and the intimate mixture is heated to about 473 K underpressure of 1 - 10 atm in the presence of cobalt catalyst which is a mixture of cobalt (100 parts), thoria (5 parts) magnesia (8 parts) and kieselghur (200parts) . A petroleum like liquid is formed which is subjected to fractional distillation to give petrol as one of the products.