Effect of Feedstock Properties on Conversion and Yields

This article discusses the effect of vacuum gas oil properties on reactivity, conversion, and yields in fluid catalytic cracking and thermal cracking. Literature data for catalytic cracking of 35 vacuum gas oils and thermal cracking of four vacuum gas oils were processed and correlations were developed. The vacuum gas oil reactivity in both fluid catalytic cracking and thermal cracking was found to increase with the saturate content, and decrease with the aromatic carbon content. At approximately the same conversion level thermal cracking yields the same diesel as fluid catalytic cracking, and half the gasoline yield of fluid catalytic cracking at the expense of a much higher gas yield. The characterization of the vacuum gas oils used as feedstocks for fluid catalytic cracking and thermal cracking by their saturate, aromatic carbon and hydrogen contents gives reliable information for prediction of conversion and yields in both heavy oil conversion processes. The higher the saturate and hydrogen contents, and the lower the aromatic carbon content the higher the conversion in both fluid catalytic cracking and thermal cracking.