What question did this study set out to answer?

This work aims to develop an empirical model for the yield profile of fluid catalytic cracking to optimize light cycle oil production.

May 9, 2026

Evaluation of a Catalytic Cracking Reactor Operating in a Broad Conversion Range: Part I – Empirical Model Development from Pilot Plant Experiments

Key Points

This work aims to develop an empirical model for the yield profile of fluid catalytic cracking to optimize light cycle oil production.
Data were collected from experimental runs in a large FCC pilot plant at 200 kg/h rate using five batches of vacuum gasoil.
The empirical model incorporated factors such as reaction temperature, catalyst-to-oil mass ratio, and contact time, normalized between -1 and +1.
Statistical methods including restricted least squares and cross-validation were employed to validate the model and avoid overfitting.
The empirical model demonstrated an R2 value between 0.95 and 0.97 for most lumped products, indicating strong predictive capability.
Light Cycle Oil yield variation was significantly lower compared to naphtha or slurry oil, with operating at low conversion identified as advantageous for increased diesel production.
The model aids in evaluating the more profitable operating mode for an FCC unit.

Abstract

Fluid catalytic cracking (FCC) is a major conversion process in the production scheme of a refinery. Among the products, Light Cycle Oil (LCO) is an important middle-cut stream that may become a focus of attention if a refinery is required to increase the diesel/gasoline production ratio. The present work presents an empirical model for the FCC yield profile, exploring the low conversion region (favoring higher LCO formation). Data were taken from experimental runs performed in a large FCC pilot plant using five different batches of vacuum gasoil from a commercial FCC unit at a 200 kg/h rate and a catalytic system aimed at maximizing LCO. With regard to the empirical model, the explanatory variables associated with the reaction severity level in the Riser were: reaction temperature (Trx), catalyst-to-oil mass ratio (CTO), and contact time between the feed and catalyst in the Riser reactor (tc); while the light hydrocarbons content of the feed (HClight), i.e., the wt % of feed with a boiling point lower than 343 °C, was considered as the factor associated with the feedstock characterization. The empirical model describing the catalytic cracking yield profile was developed through combinations of these factors normalized between −1 and +1, using a cross-validation Monte Carlo-based method to avoid model overfitting. Factors were accepted in the model only if their associated parameters were significant according to the statistical tests. Restricted least squares were also employed to ensure closed mass balances. Results indicated LCO as an intermediate product, with much lower yield variation compared to naphtha or slurry oil. Although there is the disadvantage of an increased slurry oil yield, operating the FCC at low conversion presents a potential opportunity to increase the diesel/gasoline production. The empirical model suited well with experimental data for most of the lumped groups (R2 between 0.95 and 0.97), with a higher dispersion for LPG (R2 = 0.90) and coke (R2 = 0.88), and may be a useful tool to further evaluate the more profitable operation mode of an FCC unit.

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Evaluation of a Catalytic Cracking Reactor Operating in a Broad Conversion Range: Part I – Empirical Model Development from Pilot Plant Experiments

Key Points

Abstract

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