Efficient Conversion of Light Cycle Oil into Gasoline with a Combined Hydrogenation and Catalytic Cracking Process: Effect of Pre-distillation

Abstract

The combined hydrogenation and catalytic cracking (HCC) process is reported to be able to convert inferior light cycle oil (LCO) into high-quality gasoline efficiently. However, when the LCO rich in tricyclic aromatic hydrocarbons (TAHs) is used as feedstock, a high hydrogenation severity is required to saturate the aromatic rings and abundant gaseous hydrocarbons are generated during the following catalytic cracking process, thereby reducing the gasoline yield and its quality. In this work, the LCO was distilled into light, middle, and heavy fractions, which were rich in mononuclear aromatic hydrocarbons (MAHs), bicyclic aromatic hydrocarbons (BAHs), and TAHs, respectively. Based on the systematic analysis of compositions of hydrogenated LCO fractions and their catalytic cracking products, the optimal hydrogenation severities for each fraction to achieve the maximum gasoline production were determined. A novel combined process of selective hydrogenation and catalytic cracking based on predistillation (SHCC-PD) was further proposed. In the SHCC-PD process, LCO was primarily distilled and selectively hydrogenated, thereby delivering an improved catalytic cracking performance with an LCO conversion of ∼66 wt % and selectivity of high-quality gasoline of ∼72 wt %.