In Situ EXAFS Study of the Sulfidation of an Hydrotreating Catalyst Doped with a Non Chelating Organic Additive

Abstract

Résumé -Étude par absorption X in situ de la sulfuration d'un catalyseur d'hydrotraitement dopé par un composé organique non chélatant -Un catalyseur industriel de type CoMoP supporté sur alumine a été imprégné à sec par une solution aqueuse de diéthyleneglycolbutyléther (DEGbe) puis séché à 393 K pendant 12 h. Après activation sous H 2 /H 2 S, ce catalyseur se révèle plus actif que la référence non modifiée. Afin de comprendre l'effet de cet additif organique sur la cinétique de sulfuration, des analyses in situ par EXAFS au seuils K du cobalt et du molybdène ont été réalisées. Ces caractérisations ont été effectuées sur le catalyseur CoMoP + DEGbe séché à 393 K, sulfuré à température ambiante, puis à 373 et 473 K. La sulfuration du cobalt et surtout celle du molybdène sont inhibées par la présence du composé organique jusqu'à environ 473 K. Les résultats EXAFS obtenus dans le cadre de cette étude ont permis de mieux appréhender le rôle des composés organiques ajoutés aux catalyseurs d'hydrotraitement. Ces composés ralentissent la sulfuration du Mo et du Co présents sur le catalyseur. Abstract -In Situ EXAFS Study of the Sulfidation of an Hydrotreating Catalyst Doped with a Non Chelating Organic Additive -An industrial alumina-supported CoMoP catalyst was impregnated (incipient wetness method) with an aqueous solution of diethyleneglycolbutylether (DEGbe) and then dried at 393 K overnight. After sulfidation under H 2 /H 2 S, this catalyst has a higher activity than the non impregnated CoMoP. In order to check if the presence of such an organic additive in contact with the oxidic form of the active phase influences the kinetics of sulfidation of the cobalt and the molybdenum, EXAFS spectroscopy (K-Co or K- Synchrotron and Neutron Solutions to Oil Industry ProblemsUtilisation des grands instruments analytiques dans l'industrie pétrolière

NiMo/alumina hydrodesulphurization catalyst modified by saccharose: Effect of addition stage of organic modifier

“…However, other investigators have reported significant improvements in the HDS activity of commercial (calcined) CoMo/alumina formulations through modification with glycols. For instance, Mazoyer found enhanced activity in both tetralin hydrogenation and 4,6‐dimethyl‐DBT HDS (about 33 and 48 %, respectively) of CoMo/Al 2 O 3 catalysts impregnated with diethyleneglycol n ‐butylether. Additionally, increased selectivity to products from the direct desulphuration route (Scheme ) suggested better promotion of MoS 2 crystals by Co .…”

“…[46] However, other investigators have reported significant improvements in the HDS activity of commercial (calcined) CoMo/ alumina formulations through modification with glycols. For instance, Mazoyer [47] found enhanced activity in both tetralin hydrogenation and 4,6-dimethyl-DBT HDS (about 33 and 48 %, respectively) of CoMo/Al 2 O 3 catalysts impregnated with diethyleneglycol n-butylether. Additionally, increased selectivity to products from the direct desulphuration route (Scheme 2) suggested better promotion of MoS 2 crystals by Co. [48,49] Further, according to Geantet et al, [9] an industrial calcined CoMoP catalyst impregnated with TEG in an aqueous solution increased its HDS activity by more than twice when tested in desulphurization of both 4,6-dimethyl-DBT and real feedstock (straight-run gas oil).…”

Maleic acid, an efficient additive for the activation of regenerated CoMo/Al2O3 hydrotreating catalysts

“…Two main distinct families of additives can be distinguished: glycol-type agents and chelating or complexing agents. The use of glycol-type agents was largely employed to optimize the preparation of MoS 2 -based catalysts [12,[17][18][19]. The main effect of glycol-type agents seems to be related to a redispersion of molybdic species at the catalyst surface leading to a higher proportion of less polymerized heteropolymolybdate species containing also cobalt, particularly for phosphorus-doped CoMo catalysts.…”

Highly active P-doped sulfided NiMo/alumina HDS catalysts from Mo-blue by using saccharose as reducing agents precursor

“…Regarding non-chelating ligands as HDS catalysts additive so far no general agreement about the origin of their beneficial influence has been reached. It appears that enhanced HDS activity could be originated by a number of factors [3][4][5][6][7][8][9]. For instance, for P-doped CoMo/ Al 2 O 3 formulations impregnated in glycols presence it has been proposed that the interaction of the organic additive with both basic OH groups and coordinatively unsaturated Al 3+ sites on the alumina surface could partially prevent Co diphosphopentamolybdate (Strandberg heteropolyanions [10]) complexes decomposition during their deposition on the carrier [4].…”

“…Thus, close proximity of Co and Mo in those complexes could result in formation of increased amount of the socalled "CoMoS phase" during sulfiding. Others [7] found optimized promoter integration to MoS 2 phase in catalysts prepared in presence of glycols (di-ethyleneglycolbutylether). They observed that Mo and Co sulfidation took place at temperatures up to 473 K, this fact probably contributing to better integration of cobalt promoter to edge sites of molybdenum sulfide particles.…”