Role of Catalytic Metals in Hydrocracking

Beuther, H.; Larson, O.A.

doi:10.1021/i260014a010

Cited by 24 publications

(13 citation statements)

References 7 publications

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“…The deactivation of the catalyst was most likely due to the accumulation of carbonaceous deposits (coke) on the surface. A theory advanced by Beuther and Larson (1965) to explain the deactivation of hydrocracking catalysts seems to be applicable to the NiMo/Al203 catalyst as well. It is postulated that during deactivation, coking eventually occurs on all hydrogenolysis sites not in the vicinity of a "protective" hydrogenation site, which through its catalytic activity is much less susceptible to coking.…”

Section: -17)mentioning

confidence: 99%

Reaction network and kinetics of the vapor-phase catalytic hydrodenitrogenation of quinoline

Satterfield¹,

Cocchetto²

1981

Ind. Eng. Chem. Proc. Des. Dev.

131

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The reaction network and kinetics of quinoline hydrodenitogenation (HDN) were studied in a flow microreactor packed with presulfided NiMo/A1 2 0 3 catalyst. Reactor temperatures were 330 to 420 0 C, and total pressure was either 3.55 or 7.0 MPa (500.or 1000 psig).Partial pressure of the reactant compound (quinoline or one of its hydrogenated derivatives) was 13.3 or 26.7 kPa, and reactant feed rates varied from 41.7 to 667 hr g catalyst/g-mol.The results indicated that the initial ring saturation reactions of quinoline are all reversible over a wide range of HDN conditions; also, saturation of the aromatic ring is thermodynamically (but not necessarily kinetically) more favorable than saturation of the heteroring. Nitrogen removal from quinoline occurred primarily through the decahydroquinoline intermediate, and propylcyclohexane was the major hydrocarbon product. The NiMo/Al?0 3 catalyst exhibited little selectivity for the reaction pathway of minimum hydrogen consumption, due to insufficient hydrogenolysis activity.Adsorptivities of the nitrogen compounds in the quinoline HDN network varied significantly. A Langmuir-Hinshelwood kinetic model, allowing for these different adsorptivities, was developed for the hydrogenolysis and nitrogen removal reactions. On active catalyst sites, the Py-tetrahydroquinoline and decahydroquinoline reaction intermediates appeared to adsorb about six times as strongly as the less basic aromatic amines (quinoline, Bz-tetrahydroquinoline, and o-propylaniline), which in turn showed an adsorption strength approximately four times greater than that of ammonia.

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Section: -17)mentioning

confidence: 99%

Reaction network and kinetics of the vapor-phase catalytic hydrodenitrogenation of quinoline

Satterfield¹,

Cocchetto²

1981

Ind. Eng. Chem. Proc. Des. Dev.

131

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“…For example, when choosing the appropriate hydrogenatingdehydrogenating function, it must be considered if the feed contains catalyst poisons such as sulfur, nitrogen and oxygen which make infeasible the use of noble metals (Kriz et al, 1983). Also, if a catalyst with a given acidity is to be used for obtaining products with a boiling point similar to the feed and with high saturation of the aromatic fraction a noble metal instead of a non noble metal would be recommended as the hydrogenating function (Beuther and Larson, 1965;Coonradt and Garwood, 1964). On the other hand catalysts with a high acidity/hydrogenation ratio should be prepared if products with a ratio of branched to normal paraffins higher than the feed, and therefore gasoline with a higher octane number, are to be obtained.…”

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confidence: 99%

Hydrocracking of n‐heptane. Study of NiO—MoO₃ catalysts supported on a HY ultrastable zeolite

et al. 1986

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The hydrocracking of n‐heptane in the temperature range of 573 to 623 K and at 2.45 × 106 Pa pressure has been employed as a test reaction for the study of Ni—Mo bifunctional catalysts supported on a HY ultrastable zeolite. Two groups of catalysts containing 8 and 12 wt% of MoO3 and different amounts of NiO have been studied. In both series a maximum in the activity has been obtained for catalysts with a Ni/Mo atomic ratio of 0.8‐1.0. The order of the impregnation of the oxides can have little influence on the activity. The most active catalyst has been obtained when the zeolite is exchanged with NH+4 ions until the Na+ level is less than 2% of the original and calcined at 823 K to obtain a HY ultrastable zeolite. Using this catalyst the rate controlling step could be the transformation of the carbonium ion on the acid sites.

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“…To restore the density we need to enhance the hydrogen activity by improved metal utilization and, if necessary, higher loading. The metal, Pd in the current work, produces atomic H, which is needed to remove the surface carbon [28]. Methane production with an apparent activation energy of 130-150 kJ/mol (Fig.…”

Section: Apparent Activation Energies and Temperature Effectsmentioning

confidence: 82%

Methyldecalin hydrocracking over palladium/zeolite-X

2001

Fuel and Energy Abstracts

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Hydrocracking of methyldecalin over Pd/REX has been studied with surface sensitive techniques in the critical temperature range 325-350ЊC. Results from in situ characterization of adsorbed species, and post-reaction analysis of the catalyst surface by infrared and photoemission spectroscopies, were related to product distributions. The results are discussed in light of quantum chemical calculations of free and catalyst bound intermediates, following ring-opening reactions. Liquid and gaseous products were detected by infrared and UV/Vis spectroscopies. Apparent activation energies of product formation hydrogen consumption, over a broader temperature range, were derived from previous autoclave experiments.An increase in temperature, 325-350ЊC, results in a shift from preferred cracking products to aromatics, an enhanced level of light hydrocarbon off-gases, and a higher coverage of carbonaceous residues. The increased level of carbonaceous residues is accompanied by a lowered coverage of the reactant, at the surface. The altered product distribution can be characterized by apparent single activation energies, valid from 300 to 450ЊC. Methane and aromatics show a similar rapid increase with temperature, hydrogen consumption a more timid increase, indicating a reaction limited by diffusion, and cycloalkane production a modest inverse temperature dependence.Fully hydrogenated ring-opening products represent valuable fuel components, but hydrogen deficiency can instead lead to chemisorbed precursors to coke. Our calculations show that cyclohexane, 1,2-diethyl, 3-methyl has a lower heat of formation than the corresponding surface intermediates, but a small enthalpy advantage can easily be countered by entropy effects at higher temperatures. This balance is critical to the formation of preferred products, instead of catalyst deactivation and aromatics. The theoretical results further show that surface intermediates, where the terminating hydrogen is replaced by a C-O bond, have distinct vibrations around 1150 cm Ϫ1 . ᭧

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Role of Catalytic Metals in Hydrocracking

Cited by 24 publications

References 7 publications

Reaction network and kinetics of the vapor-phase catalytic hydrodenitrogenation of quinoline

Reaction network and kinetics of the vapor-phase catalytic hydrodenitrogenation of quinoline

Hydrocracking of n‐heptane. Study of NiO—MoO₃ catalysts supported on a HY ultrastable zeolite

Methyldecalin hydrocracking over palladium/zeolite-X

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Role of Catalytic Metals in Hydrocracking

Cited by 24 publications

References 7 publications

Reaction network and kinetics of the vapor-phase catalytic hydrodenitrogenation of quinoline

Reaction network and kinetics of the vapor-phase catalytic hydrodenitrogenation of quinoline

Hydrocracking of n‐heptane. Study of NiO—MoO3 catalysts supported on a HY ultrastable zeolite

Methyldecalin hydrocracking over palladium/zeolite-X

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Hydrocracking of n‐heptane. Study of NiO—MoO₃ catalysts supported on a HY ultrastable zeolite