Paraffinic stocks are easy to crack and normally yield the greatest amount of total liquid products. Normal paraffin will crack mostly to olefin and other paraffin molecules.
These processes include thermal cracking and other catalytic cracking operations. Olefins are not the preferred feedstocks to an FCC unit. This is not because olefins are inherently bad, but because olefins in the FCC feed indicate thermally produced oil. They often polymerize to form undesirable products such as slurry and coke.
Naphthenes are desirable FCC feedstocks because they produce high-octane gasoline. The gasoline derived from the cracking of naphthenes has more aromatics and is heavier than the gasoline produced from the cracking of paraffins.
In comparison with cracking paraffins, cracking aromatic stocks results in lower conversion, lower gasoline yield, and less liquid volume gain, but with higher gasoline