The fluid catalytic cracking (FCC) behavior of compound types present in the >650 °F resid from Brass River (Nigerian) crude was investigated. Liquid chromatography and distillation were employed for separation of selected compound type fractions from the resid; the resulting fractions were then cracked using a bench scale FCC unit. The FCC behavior for each compound type was defined in terms of the resulting product distribution (yields of gas, gasoline, etc.) sulfur and nitrogen partitioning, and in selected cases, gasoline composition. Results obtained from Brass River fractions were compared to those obtained from an earlier FCC study of compound types from Wilmington, CA, >650 °F resid. Correlations were derived for gasoline and coke yields from feedstocks derived from either crude. Brass River is a sweet, paraffinic crude which gives rise to a >650 °F resid with very favorable FCC characteristics. Although the bulk of the FCC gasoline was produced from cracking hydrocarbon types present, significant gasoline production also occurred from heteroatomic compounds (acids/bases) in Brass River. Conversely, negligible gasoline production was observed previously from cracking Wilmington acid/base types. However, feedstocks from both crudes exhibited greater conversion of sulfide sulfur to H2S compared to thiophenic forms of sulfur, and greater carryover of acidic forms of nitrogen (e.g., carbazole) compared to basic forms (e.g., quinoline). Overall gasoline composition depended on hydrocarbon type composition of feedstocks but was also influenced by presence of acids and/or bases in the feed. On the other hand, the detailed distribution of isomers within a given gasoline homolog, e.g., C3-benzenes or C9 isoparaffins, was nearly independent of feed composition. Results obtained for Brass River will serve as benchmarks for future FCC data obtained from low-quality feedstocks.

The pendant−core concept has been used previously to predict product slates from catalytic cracking. In this concept, alkyl side chains and analogous moieties are defined as “pendants”, which are attached to a cluster of aromatic and/or naphthenic rings which is referred to as the “core”. This work extends the pendant−core concept via a model which correlates feed composition (19 main component types determined by mass spectroscopy) to nine product subclasses (both gasoline and non-gasoline) by adding product distribution functions. These product distribution functions depend upon the feed component class (saturates, aromatics, and sulfur compounds) and upon the core−pendant ratio. For example, the production of light gas and coke increases with the core−pendant ratio since the probability of coke formation increases with core size and the average pendant chain length decreases as the proportion of carbon in pendants decreases. Using these component distribution functions, and the mass spectroscopic analysis of feeds, one can calculate anticipated yields of nine product subclasses:  light gas, C3/C4 gas, light cycle oils, heavy cycle oils, coke, and gasoline range:  paraffins, olefins, aromatics, and naphthenes. The product distribution functions were developed from data on four feedstocks. For the four feedstocks used in the correlation, plus a fifth feedstock, the predicted product quantities are within 2 wt % of the experimental values. The present form of the model does not address effects of polar (acidic or basic) compounds in feeds on product slate.