Applied Catalysis B: Environmental 42 (2003) 145–154 Effect of highly reactive sulfur species on sulfur reduction in cracking gasoline Francisco Hernández-Beltrán a,∗ , Roberto Quintana-Solórzano a , Jaime Sánchez-Valente a , Francisco Pedraza-Archila a , François Figueras b a Instituto Mexicano del Petróleo, Eje Central L. Cárdenas 152, 07730 México, D.F., Mexico b Institut de Recherche sur la Catalyse, 2 Avenue A. Einstein, 69626 Villeurbane Cédex, France Received 29 March 2002; received in revised form 26 August 2002; accepted 28 August 2002 Abstract Stringent regulations for engine fuels have stimulated R&D work for reducing sulfur in cracked naphtha in the recent years. In order to progress in this issue information on the effect of the chemistry of sulfur compounds under cracking conditions is needed. In this work, hexyl-2-thiol was spiked in a gasoil feed and the effect on sulfur in gasoline was studied with an equilibrium catalyst (Ecat) and a commercial gasoline sulfur reduction additive. Spiked feeds showed lower conversion. The hexyl-2-thiol mainly produced H 2 S and exhibited a competitive reaction with sulfur compounds contained in gasoil. Higher amounts of sulfur-in-coke were produced with the Ecat-additive blend compared to Ecat thus indicating that the hexyl-2-thiol adsorbs stronger on the additive which can be due to its Lewis acid properties. While the additive moderates the detrimental effect of hexyl-2-thiol on the catalyst activity its activity for sulfur reduction in gasoline was constrained. © 2002 Elsevier Science B.V. All rights reserved. Keywords: FCC; Sulfur in gasoline; Sulfur reducing additive; Thiophene; Benzothiophene; Alkylthiophenes; Sulfur-in-coke 1. Introduction Sulfur compounds in gasolines contribute to in- crease SO x emissions in combustion gases produced by automotive engines and poison the automotive cat- alytic converters active metals thus lowering their effi- ciency to reduce atmospheric pollutants such as NO x . Among the increasingly stringent fuels specifications that are being imposed in the US by the Tier II reg- ulations for the following years, the concentration of sulfur in commercial gasoline is focused with special care. The upper limit of sulfur in gasoline in US for ∗ Corresponding author. Tel.: +52-3003-8539; fax: +52-5003-8541. E-mail address: fjhernan@imp.mx (F. Hern´ andez-Beltr´ an). 2005 has been set to 30 ppmw as a refinery average [1–3]. Canada and the European Union have adopted similar specifications. Moreover, the introduction of “sulfur free fuels” (<10 ppmw S) have been proposed in Europe for year 2007 [1,2]. Commercial gasolines are complex blends of streams and products from several petrochemical and refining processes. One of the major contributors to the refinery gasoline pool is the fluid catalytic crack- ing (FCC) [1] process with 35 vol.% average. The FCC gasoline contributes to more than 90% to the total gasoline pool sulfur content [1,3]. The amount and distribution of sulfur compounds in the cracking products from FCC depends mainly on the sulfur content and the type of feed [4–6]. Other variables such as the type of catalyst and the operating 0926-3373/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0926-3373(02)00237-0