The effects of hydrogenation and catalytic cracking of various molecular types in middle distillates

Abstract

The response to hydrogenation and catalytic cracking of the various types of hydrocarbons present in petroleum gas oils has been investigated by mass spectrometric analytical techniques. A substantial difference was found between the ease of hydrogenation of mononuclear and dinuclear aromatic compounds. A similar difference does not appear to exist between dinuclear and polynuclear aromatic systems. Some polynuclear compounds are apparently hydrogenated completely under conditions which do not normally saturate mono ring aromatics. In catalytic cracking, it appears that aromatic compounds are affected largely by the cracking of aliphatic appendages and very few aromatic rings are broken, whereas entirely aliphatic materials present in the reactant stream are cracked quite readily. It is well known that hydrogenation is beneficial to a catalytic cracking charge stock. This work shows that relatively mild hydrogenation of materials which are to be catalytically cracked can, by saturating polyaromatics only to monoaromatics (naphthenes), make the stock much more susceptible to cracking.