Browsing by Author "Ternan, Marten"

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    Effect of H-Mordenite Zeolite as a Component in Co-Mo-Al2O3 Hydroprocessing Catalysts Used for the Conversion of Boscan Heavy Oil
    (Elsevier, 1991) Minja, Rwaichi J. A.; Ternan, Marten
    The effect of H-mordenite zeolite as a component in Co-Mo-Al2O3 hydroprocessing catalysts has been studied. Catalysts containing up to 20% H-mordenite were used for hydrocracking Boscan heavy oil at 13.9 MPa. Although the acidic sites on the external surface of the zeolite crystals were expected to increase cracking reactions, little effect on conversion was observed. As the H-mordenite content of the catalyst increased, the bulk density and the specific surface area of the catalysts decreased substantially. When the reaction results were expressed on the basis of constant residence time and constant catalyst surface area there was an increase in the reaction parameter with increasing H-mordenite content of the catalyst. It was also found that coke deposition increased with the increasing H-mordenite content of the catalyst. These two observations suggest that H-mordenite caused an increase in the number of acidic sites in the catalyst. The results indicate that catalysts with H-mordenite would produce greater conversions than catalysts without H-mordenite, if the extrudates could be prepared in such a way that the catalyst bulk density does not change when the H-mordenite is added.
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    Hydrocracking Boscan Heavy Oil with a Cobalt-Molybdenum/Alumina Catalyst Containing an H-Mordenite Zeolite Component
    (1991) Minja, Rwaichi J. A.; Ternan, Marten
    Co-Mo/Al2O3 catalysts for hydrocracking heavy oil and residue were modified by adding up to 20 wt % hydrogen-mordenite zeolite. The acidic sites on the external surface of the mordenite crystals were expected to increase cracking reactions. In fact, there was a slight decrease in the +525-degrees-C resid conversion, although vanadium and nickel hydrodemetallization increased as the mordenite content of the catalyst increased. On the other hand, the pseudo turnover frequency for metals removal, i.e, the number of reactions per second per reaction site (or in this case per (nm)2), was greater for catalysts containing greater amounts of mordenite. The catalyst performance was attributed to a combination of two factors. First, both the catalyst bulk density (grams of catalyst per milliliter of reactor volume) and the catalyst specific surface area (m2/g) in pores larger than 3 nm decreased as the mordenite content increased. Hence, a smaller quantity of catalyst could be placed into the reactor and the catalyst that was in the reactor had less surface area per unit mass. Clearly the mordenite changed the structure of the alumina support, which resulted in a net decrease in the effective catalyst surface area. Second, the catalyst acidity, as measured by temperature-programmed desorption of benzofuran, increased as the mordenite component of the catalyst increased. It was concluded that the improved overall hydrodemetallization was caused by both the increased number of acidic sites of the exterior surfaces of the mordenite and the changes in catalyst pore geometry, which improved the rate of diffusion to the catalyst surface.
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    Hydrocracking Boscan Heavy Oil with a Como/Al Sub 2 O Sub 3 Catalyst Containing an H-Mordenite Zeolite Component
    (2009-01) Minja, Rwaichi J. A.; Ternan, Marten
    Co-Mo/AlâOâ catalysts for hydrocracking heavy oil and residue were modified by adding up to 20 wt % hydrogen-mordenite zeolite. The acidic sites on the external surface of the mordenite crystals were expected to increase cracking reactions. In fact, there was a slight decrease in the +525°C resid conversion, although vanadium and nickel hydrodemetallization increased as the mordenite content of the catalyst increased. On the other hand, the pseudo turnover frequency for metals removal, i.e., the number of reactions per second per reaction site (or in this case per (nm)²), was greater for catalysts containing greater amounts of mordenite. The catalyst performance was attributed to a combination of two factors. First, both the catalyst bulk density (grams of catalyst per milliliter of reactor volume) and the catalyst specific surface area (m²/g) in pores larger than 3 nm decreased as the mordenite content increased. Hence, a smaller quantity of catalyst could be placed into the reactor and the catalyst that was in the reactor had less surface area per unit mass. Clearly the mordenite changed the structure of the alumina support, which resulted in a net decrease in the effective catalyst surface area. Second, the catalyst acidity, as measured by temperature-programmed desorption of benzofuran, increased as the mordenite component of the catalyst increased. It was concluded that the improved overall hydrodemetallization was caused by both the increased number of acidic sites of the exterior surfaces of the mordenite and the changes in catalyst pore geometry, which improved the rate of diffusion to the catalyst surface.