Selective ring opening of naphthenes: From mechanistic studies with a model feed to the upgrading of a hydrotreated light cycle oil

• Published in: Fuel (Guildford) Vol. 111; pp. 763 - 770
• Main Authors: Calemma, V., Ferrari, M., Rabl, S., Weitkamp, J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2013; Elsevier
• Subjects: Alkanes; Applied sciences; Bifunctional catalysis; Catalysis; Catalysts; Cetane; Cetane Index; Concentration (composition); Crude oil, natural gas and petroleum products; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fuels; LCO; Naphthenes; Processing of crude oil and oils from shales and tar sands. Processes. Equipment. Refinery and treatment units; Pt/Y; Ring opening; Selective ring opening; Upgrading; Cetane Index; Pt/Y; LCO; Bifunctional catalysis; Selective ring opening; Fixed bed reactor; Chemical structure; Zeolite; Naphthenic hydrocarbon; Molecular sieve; Case study; Light oil; Hydrocracking; Platinum; Upgrading; Alkane; Cyclohexane; Cetane number; Chemical composition; Catalysis; Iridium; By product; Catalyst; Strength
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2013.04.055

•Iridium and platinum based catalysts, with high selective ring opening selectivity were used to upgrade a hydrotreated LCO.•Hydroconversion of hydrotreated LCO resulted in a strong decrease of condensed naphthenic structures.•Changes in chemical structure led to a remarkable increase of Cetane Index with relatively low cracking yields.•It is shown the possibility to upgrade aromatic rich streams to products meeting the Cetane Number specification of gasoil.•Testing ring-opening catalysts with decalin enables to investigate the main factors affecting the ring-opening reaction. The catalytic hydroconversion of desulfurized and dearomatized light cycle oil (DeAr-LCO) with a Cetane Index (CI) of 41.7 was investigated at 7.0MPa and in the temperature range from 290 to 350°C in a down-flow fixed bed reactor. Two catalysts made up, respectively, of 3wt% iridium and 4wt% platinum loaded on Y zeolite exchanged with Na were used. The hydroconversion of DeAr-LCO over the above-mentioned catalysts resulted in a remarkable change of chemical structure of the feed with a strong decrease of condensed naphthenic structures and a concomitant increase of alkyl substituted cyclohexanes and open-chain alkanes. In the case of tests carried out with the platinum-based catalyst the alkanes concentration passed from 21% in the feed to 44% in the product obtained at the highest conversion levels. GCxGC-MS analyses showed that the hydrocracking associated with the hydroconversion process was relatively modest and that the observed changes in chemical composition were mainly the consequence of the selective ring opening pathway of naphthenic structures. The results clearly show that along with the changes in chemical structure during hydroconversion the products are characterized by a higher CI. For the platinum- and iridium-based catalysts an increase of CI of 11 and 7 units, respectively, was observed at a gasoil yield of 80wt%. The positive results indicate that the use of a metal function with a high hydrogenolytic activity and selectivity coupled with a properly tuned concentration and strength of the Brønsted acidic sites can lead to remarkable improvements in the cetane properties of gasoil cuts. The practical consequence of this result is the possibility of upgrading aromatic-rich streams to products meeting the current Cetane Number specification of gasoil.