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.

The study of a light cycle oil (LCO) upgrading alternative involving hydrotreating and hydrocracking/transalkylation procedures for obtaining a benzene, toluene and xylene (BTX) enriched fraction is presented. The research work was focused on the effect of the experimental conditions on the hydrocracking of an hydrotreated light cycle oil (HDT LCO) in order to produce the highest amounts of BTX, when the catalysts consisted of a mixture (50/50 in weight) of nickel-molybdenum on alumina (NiMo/Al 2 O 3) and ZSM-5 materials (NiMo/ZSM-5 (50)). It was found that 7.4 MPa, up to 375 °C, LHSV of 1.2 h −1 and a H 2 /Oil value of 442 m 3 /m 3 were the optimal experimental conditions for producing an enriched BTX fraction (31%). In order to facilitate the analysis, the study was carried out considering four types of hydrocarbons as lumps for the feed and HCK products: light hydrocarbons (LHC) composed by C4-C7 non-aromatic compounds, BTX, middle hydrocarbons (MHC) consisting of C7-C10 paraffins and isoparaffins, alkylbenzenes, tetralin and naphthalene derivatives and a small amount of high molecular weight hydrocarbons (HHC). Based on this description, HDT LCO used as feedstock for the hydrocracking (HCK) procedure, presents a 99% of a MHC fraction. The HCK conversion, BTX selectivity and yields were obtained from the chromatographic analysis of the products. A simple kinetic model considering only the MHC conversion was carried out. The obtained activation energy confirmed the endothermic nature of the HCK process. The activity decay of the catalytic mixture was also studied by varying the time on stream.

The study of the best experimental conditions and catalyst for the hydrogenation (HYD) of light cycle oil (LCO) for upgrading purposes was carried out. The objective was to examine the ability of two commercial hydrotreatment (HDT) catalysts for selective aromatic saturation. The effect of the hydrotreatment operation parameters (temperature, pressure, liquid hourly space velocity, H2/HC ratio) on the sulfur and nitrogen contents and in the saturation of aromatic hydrocarbons was also investigated. The goal was to obtain the highest conversion to mono-aromatic hydrocarbons from this di-aromatic (naphthalene derivatives) type feedstock, and at the same time to get reasonable hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) performance to avoid contaminant hydrocarbons for the next step (usually hydrocracking, HCK). An appropriate hydrotreated product with the highest concentration of mono-aromatic derivatives, a minimum reduction on the total aromatic content, and suitable decrements of sulfur and nitrogen compounds, was achieved using a cobalt-molybdenum supported on alumina catalyst, at 330 °C, 5.5 MPa, and a liquid hourly space velocity of 1.1 h−1. Additionally, the kinetics of the HDA was studied, assuming a lump characterization into tri-, di- and mono-aromatic and aliphatic hydrocarbons, pseudo-first-order reaction rates between these conversions, and thermal losses and diffusional resistances to be undetectable.

The effect of the chemical composition of the hydrotreated light cycle oil (HDT LCO) on the benzene, toluene, ethylbenzene, and xylene (BTEX) production by a hydrocracking (HCK) procedure, is presented. Six different types of HDT LCOs were obtained by submitting two types of LCOs to hydrotreating (HDT) with different catalysts and experimental conditions. The products were analyzed as mono-, di- and tri-aromatic compounds using the supercritical fluid chromatography (SFC) method (ASTM D5186). The HDT LCOs were subjected to HCK with a 50/50 in weight mixture of nickel-molybdenum on alumina (NiMo/Al2O3) and H-ZSM5 (NiMo/H-ZSM5, 50/50) at 375 °C, 7.5 MPa, 1.2 h−1, and 750 m3/m3 H2/Oil. The HCK products were analyzed by gas chromatography with a flame ionization detector (GC-FID) and divided into five groups: gas, light hydrocarbons (LHCs), BTEX, middle hydrocarbons (MHCs), and heavy hydrocarbons (HHCs).The results showed that the BTEX formation ranged from 27.0 to 29.8 wt.% and it did not show a significant dependence on the mono-aromatic (59.9 and 75.6 wt.%), total aromatic (61.1–84.2 wt.%) contents or MHCs conversion (58.3–64.3 wt.%) from the departing HDT LCO feedstock. This result implies that, contrary to previous expectations, the BTEX formation does not directly depend on the amounts of total or mono-aromatic compounds when departing from real feedstocks. A GC-PIONA (paraffin, isoparaffin, olefin, naphthene, aromatic) characterization method (ASTM D6623) for mechanism understanding purpose was also carried out.

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