Effects of median pore diameters in co/mo/al 203 catalysts on the conversion of Athabasca bitumen

Bitumen hydroprocessing: Effects of metal loading and promoters in Mo‐Al2 O3 catalytic systems

“…The relatively high effectiveness of low concentration catalysts has been attributed to diffusional limitations within catalyst pores (Hardin et al 1978). As mentioned previously, the number of catalytic sites increases with metal loading enhancing the specific reaction rate on a diffusionfree basis.…”

“…However, at high conversion levels of residuum (525"C-t hydrocarbon material) catalyst deactivation by coke deposition rapidly reduces the initial effectiveness of these catalysts (McColgan and Parsons, 1974). Some improvement in the short term, such as up to 10 hours, can be brought about by altering the chemical composition (Kelly and Ternan, 1979), (Ternan et al 1979) and pore structure (Hardin et al 1978), but such changes have little effect on long-run activity, e.g., 100 hours or more (Ternan and Kriz, 1980). Metal loading of the principal constituents and the promoters is an important variable in determining catalyst effectiveness.…”

Effect of nonuniform activity on hydrodemetallation catalyst

“…Hung et al ( I 986) observed that vanadium distribution factors for unimodal pore size cylindrical catalysts increased from Rmj, = I0 wt. % metal/yr by Hardin et al (1978) and Shimura et al (1986) in catalysts with a less narrow pore size distribution. The model predicted the maximum initial activity to occur at 1.6 x lo-* m. Total metal deposition calculated by the model agrees well with that reported by Higashi et al (1985), which was over 100 wt.…”

“…Pore size optimization has been considered from both experimental (Hardin et al, 1978;Nielsen et al, 1981;Plumail et al, 1983;Shimura et al, 1986) and theoretical points of view. Many investigators have modeled the deactivation of hydrotreating catalysts.…”

Catalytic hydrogenation and asphaltene conversion of athabasca bitumen

“…Catalysts having larger pore diameters were developed in an attempt to accommodate metals deposition. In short duration experiments, it was found (Hardin et al, 1978(Hardin et al, , 1981a) that increasing the pore size of the catalyst permitted the large bitumen organometallic compounds to diffuse more readily into the interior of the catalyst pellet or ex-trudate. Therefore, the metals (resulting from the decomposition of organometallic compounds) were deposited more uniformly throughout the catalyst and pronounced pore mouth plugging did not occur.…”