Effect of feedstock hydrocarbon-group composition on kinetics of catalytic cracking

The need for a quantitative relationship between the feedstock composition and the cracking indices has become more urgent along with the development of new high-activity zeolitic catalysts which have changed the concepts of reactivity of certain groups of hydrocarbons. This paper attempts to find some simple correlation factor that will reflect the hydrocarbon group composition of the feedstock and will characterize its reactivity. It evaluates the influence of this factor on the depth and direction of catalytic cracking on zeolitic microbead catalysts. Vacuum gasoils (350-500/sup 0/C) obtained from Romashkino, Martyshinsk, and Mangyshlak crudes, differing substantially in chemical nature are used. The individual product yields and the feedstock conversion are expressed as functions of the temperature, feedstock mass velocity (FMV), and catalyst to feed (C/F) ratio. The product yields in catalytic cracking are correlated with the aromatic/paraffins (A/P) ratio in the feed when using zeolitic catalysts, and with the aromatic/naphthenes (A/N) ratio in the feed when using amorphous catalysts.