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The regular use of light cycle oil (LCO) for diesel fuel production by hydrotreatment (HDT) procedures has been facing difficulties of complying with the currently stricter environmental regulations due to the low quality of this middle distillate with high sulfur, nitrogen, and aromatic contents. An interesting alternative is to obtain valuable petrochemicals from this feedstock. LCO presents a high percentage of diaromatic hydrocarbons (naphthalene derivatives). To facilitate the study of the effect of the experimental conditions, a review regarding the hydrogenation-hydrocracking (HYD-HCK) procedures for obtaining enriched streams containing benzene, toluene, and xylene (BTX) from model mixtures (naphthalene, methylnaphthalenes, and tetralin) is presented. In addition to the economic advantages of using a middle distillate of reduced marketability, this research work opens the door to the development of technologies for obtaining valuable chemicals such as BTX from oil sources. The focus on model mixture studies facilitated the understanding of the involved kinetics and mechanisms and the effect of the experimental conditions on the chemical composition of the products as well.

The processing of light cycle oil (LCO) for diesel fuel production by the hydrotreating (HDT) process is under general re-evaluation because of current stringent environmental regulations. The low-quality of LCO with high sulfur and nitrogen, and a high percentage of diaromatic hydrocarbons, limits the possible upgrading alternatives. A HDT step, involving hydrodesulfurization, hydrodenitrogenation, and partial hydrodearomatization, is combined with a hydrocracking (HYC) step for producing (1) high-quality fuels (high-octane gasoline and ultralow sulfur diesel) and a (2) benzene, toluene, and xylenes (BTX) enriched fraction. In this review studies regarding the HDT-HYC process for producing such products from real feedstocks are considered, with the aim to provide the state of the art developments for LCO upgrading.

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Light cycle oil (LCO) is an inexpensive feedstock for the production of high-added-commercial-value-mono-aromatic compounds such as benzene, toluene and xylenes (BTX). To extend the knowledge on the processing of LCO for BTX production, the hydrocracking reaction was studied using a commercial NiMo/Al 2 O 3 catalyst, ZSM-5 zeolite and their mechanical mixtures (20/80, 30/70 and 50/50) for processing tetralin as model feedstock in a bench-scale-trickle-bed reactor at 450-500 °C, 3.9-5.9 MPa, 1.3 1/h and H 2 /feed volume ratio of 168-267 m 3 /m 3. Accessible, well-dispersed and strong Brönsted acid sites eased the hydrocracking of tetralin to BTX and the metallic hydrogenation functions from nickel-molybdenum catalysts were also required to minimize deactivation. To achieve suitable tetralin conversions (86-95 wt%), high BTX selectivity in the liquid phase (44-70 wt%) and suitable catalytic activities for coke precursor hydrogenation (to reduce deactivation), NiMo/Al 2 O 3 //ZSM-5 mixtures (50-80 ZSM-5) were employed, which probed to be effective.