Dearylation of Heavy Alkyl-Bridged Noncondensed Alkyl Diaromatics by Fluid Catalytic Cracking

Abstract

The hydrodearylation process has previously demonstrated the ability to upgrade an aromatic reject stream from an aromatic recovery complex containing heavy alkyl-bridged noncondensed multiaromatics to high-value monoaromatics that include a benzene, toluene, and ethylbenzene/xylene (BTEX) yield of ∼6 wt %. Herein, a new alternative refining processing option is presented for the same reject stream that not only improves the quality of the gasoline blending component but also significantly increases the BTEX yield. The aromatic reject stream has a limited usage as a gasoline blending component because of its inferior quality. However, by fractionating the reject stream at 180 °C, the lighter fraction can be directly sent as a gasoline blending component with a high research octane number without negatively influencing the gasoline specification, and the heavier fraction can be dearylated by subjecting the stream to fluid catalytic cracking. Gas chromatography data show monoaromatic formation at the expense of diaromatic conversion and also present BTEX yields as a function of the processing conditions. Depending on the conditions employed, the BTEX yield in the liquid product can be significantly increased (∼37 wt %) compared with the previous configuration. The significant quantities of BTEX formed demonstrate that this new processing configurationin converting low-value aromaticsprovides alternative options to refineries to upgrade the aromatic reject stream.