Characterization of dispersed hydroprocessing catalysts prepared in reversed micelles

Abstract

Fe, Co and Ni particles were prepared in water/polyoxyethylene-4-laurylether/n-hexane and water/polyoxyethylene-4-laurylether/decahydronaphthalene microemulsions by reduction of metal nitrates dissolved in the water pools of the reversed micelles. The particles were mostly monodispersed with average diameters in the range 8 to 23 nm, as determined by dynamic light scattering (DLS). However, significantly smaller size estimates were obtained using transmission electron microscopy (TEM). The average DLS particle diameters increased with increased average diameter of the reversed micelles, and the diameter of the reversed micelles increased with an increase in the microemulsion water: surfactant ratio and metal ion concentration. The diameter of the reversed micelles was also dependent upon the metal dissolved in the water pool, increasing in the order Ni < Co < Fe. These trends are explained in terms of changes that occur to the microemulsion hydrophilic-lipophilic balance. Preparation of nickel and cobalt sulfides by sulfidation of the metal salt with H,S at low temperature, yielded much larger diameter particles (average diameter 75 nm). Measurement of the activity of the sulfided catalysts showed that the Co catalyst was more active than the Ni catalyst for the hydrocracking of diphenylmethane, and Co was more effective than Fe in reducing coke yield during Cold Lake residue hydroprocessing.Des particules de Fe, Co et Ni ont ete preparees dans des microemulsions d'eadpolyoxyethylene-4-lauryletherlnhexane et d'eadpolyoxyethylene-4-laurylCther/decahydronaphthalene par reduction de nitrates metalliques dissous dans les poches d'eau des micelles inverses. Les particules etaient principalement monodisperses avec des diametres moyens compris entre 8 et 23 mm, tels qu'ils ont ete determines par diffusion de lumiere dynamique (DLS). Cependant, des estimations de tailles beaucoup plus petites ont ete obtenues au moyen de la microscopie electronique par transmission (TEM). Les diametres de particules DLS moyens augmentent avec le diametre moyen des micelles inverses, et le diametre des micelles inverses augmente avec le rapport eadsurfactant de la microemulsion et de la concentration en ions metalliques. De meme, le diametre des micelles inverses est dependant du metal dissous dans la poche d'eau, augmentant dans I'ordre Ni < Co < Fe. On explique ces tendances par le changement dans I'equilibre hydrophiliquelipophilique de la microemulsion. La preparation de sulfures de nickel et de cobalt par sulfuration du sel metallique avec du H,S a faible temperature, donne des particules aux diametres beaucoup plus larges (diametre moyen de 75 nm). La mesure de I'activite des catalyseurs sulfures montre que le catalyseur de Co est plus actif que le catalyseur de Ni pour I'hydrocraquage du diphenylmethane, et le Co est plus efficace que le Fe pour reduire le rendement en coke lors de I'hydrotraitement des residus de Cold Lake.

Slurry-Phase Hydrocracking of Residue with Ultradispersed MoS2 Catalysts Prepared by Microemulsion Methods

“…The nanosize precipitate is formed as a result of collision and coalescence of microemulsions in limited dimension of the droplets. This process has a wide range of flexibility to control the size of the finished product by varying the water/surfactant ratio, metal concentration, and type of surfactant employed . Smith and his group have used this method to prepare the dispersed catalysts. − They have used different metals, such as Fe, Co, Ni, and Mo, to prepare the micelle catalysts, and pentane, hexane, and toluene were used as solvents.…”