SEPARATIONS Novel Methodology toward Deep Desulfurization of Diesel Feed Based on the Selective Elimination of Nitrogen Compounds Mathieu Macaud, Marc Se ´ vignon, Alain Favre-Re ´ guillon, and Marc Lemaire* Laboratoire de Catalyse et Synthe ` se Organique, UMR 5181, Universite ´ Claude Bernard Lyon 1, CPE Lyon, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France Emmanuelle Schulz Laboratoire de Catalyse Mole ´ culaire, UMR 8075, Institut de Chimie Mole ´ culaire et des Mate ´ riaux d’Orsay, 91405 Orsay Cedex, France Michel Vrinat Institut de Recherches sur la Catalyse, UPR 5401, 2 avenue Albert Einstein, 69626 Villeurbanne Cedex, France π-Acceptor molecules covalently attached on hydrophilic support were used to selectively remove neutral nitrogen heterocyclic compounds from diesel feed by a charge transfer mechanism. Functionalized hydrophilic polymers can effectively adsorb nitrogen heterocyclic compounds with a high selectivity toward sulfur heterocyclic compounds from model and real feed. The results showed that charge transfer processes coupled with an ion-exchange process to selectively remove basic nitrogen compounds are efficient enough to produce denitrogenated feed in high yield. This study was conducted to determine whether trends in hydrodesulfurization (HDS) activity with lower sulfur content were mainly the result of lower reactivity of hindered sulfur compounds or due to nitrogen species inhibition. The inhibition effects of nitrogen compounds on HDS at conditions commonly used in the hydrotreatment of gas oil feedstocks has been experimentally determined. This study suggests that the selective removal of nitrogen compounds from gas oil strongly enhanced the deep desulfurization. Introduction In recent years deep desulfurization of diesel fuel has attracted much attention due to the gradual reduction of the statutory sulfur content in most western coun- tries. In 2009, the maximum S-content will be limited to 10 ppm compared to today’s value of 350 ppm S. 1 The refining industry has demonstrated its capability of adapting hydrotreatment to the stringent regulations by improving catalytic activity, increasing the process severity, especially increasing the hydrogen pressure or designing new reactor configurations. 2 However, the limited availability of hydrogen used during hydrode- sulfurization (HDS) of petroleum fractions and the more severe regulation of CO 2 emission should be also con- sidered in the selection of a new process for the hydrotreating unit. Additionally, the worldwide petro- leum reserves are becoming heavier as a result of depletion of traditional resources, increasing their sulfur and nitrogen contents. Two main routes should be considered to improve the HDS process: on one hand, the elimination of refractory sulfur species, such as 4,6-dialkyldibenzothiophenes, 3,4 and on the other hand, the elimination of HDS inhibitors 5-8 which could limit the performance of HDS catalysts. Indeed, the reactivity of nitrogen-containing compounds is much lower than that of polyaromatic sulfur compounds 9-11 although adsorption is stronger. When high levels of desulfurization are reached, the concentration of refractory sulfur compounds is very low and polyaromatics and nitrogen compounds naturally occurring in diesel fuel may inhibit the HDS process through competitive adsorption 8 and contribute to the difficulty of meeting the more stringent specifica- tions. 2,5-8,10,12 Then we could expect that elimination of HDS inhibitors such as nitrogen compounds could lead to improvement of HDS conditions. Usually, the basic nitrogen compounds have been considered to be stronger inhibitors for the HDS reac- tions than the nonbasic ones. 13-18 However, strong inhibition of these reactions by nonbasic nitrogen com- pounds has been observed, either due to hydrogenation reactions occurring during this process, which lead to the formation of basic species, or to a strong adsorption of the nonbasic compounds over the support surface, but the results seem to be inconclusive. 5,6 Furthermore, the presence of nitrogen compounds in petroleum may also * To whom correspondence should be addressed. Tel.: +33 (0)472431407. Fax: +33 (0)472431408. E-mail: marc.lemaire@univ-lyon1.fr. 7843 Ind. Eng. Chem. Res. 2004, 43, 7843-7849 10.1021/ie049465e CCC: $27.50 © 2004 American Chemical Society Published on Web 10/22/2004