ChemInform Abstract: HYDROGENATION OF PYRIDINE OVER NICKEL‐TUNGSTEN/ALUMINA CATALYST

Anabtawi, Jamal A.; Mann, R. S.; Khulbe, K.C.

doi:10.1002/chin.198036145

Cited by 2 publications

(5 citation statements)

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“…Thus, presulfiding is the essential requirement for attaining equilibrium rapidly (35). Over reduced catalysts, equilibrium becomes more complex due to the formation of dimers (e.g., n-pen-tylPIP) or even complex trimers (38,39). The alkyl substitution of the PY ring, particularly in the 2-and 2,6-positions possibly resulted in steric effects that slowed down the HYD of the N-ring (40).…”

Section: Pyridinesmentioning

confidence: 99%

“…For example, two distinct reactions for the HDN of PY were proposed by Kheberche et al (47) for a presulfided NiMo/Al 2 O 3 catalyst that was then reduced in H 2 either at 623 or at 723 K. The PIP could only be detected over the catalyst reduced at the lower temperature. Close examination of the experimental conditions suggests that these studies involved the reduced Ni(Co)Mo/Al 2 O 3 catalysts and/or the absence of H 2 S donating species in the feed (33,36,38,39,52). The adsorbed species could have been either coke or its precursor, such as dimers and trimers of PIP and n-pentylamine.…”

Section: Hydrodenitrogenation Of Petroleummentioning

confidence: 99%

“…The L-H expression was used for the modeling the kinetics of the HDN of PY over sulfided Ni(Co)Mo/Al 2 O 3 catalysts (30,32,41,129), as well as the corresponding reduced catalysts (33,38,39). The ring opening in PIP was the ratecontrolling step in the overall HDN after equilibrium was rapidly established.…”

Section: Iv11 Pyridinesmentioning

confidence: 99%

“…Apparently, for Hydrodenitrogenation of Petroleum each adsorption mode, hydrogen transfer from the surface to the adsorbed PY could be facilitated. The formation of hydrogenated dimers and trimers during the HDN of PY and PYP over reduced catalysts would suggest that such catalysts still possess HYD activity, whereas their CNH activity was much diminished (38,39,173). This mode of hydrogen activation appears to be less favorable (222).…”

Section: E Furimsky and F E Massothmentioning

confidence: 99%

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Hydrodenitrogenation of Petroleum

Furimsky¹,

2005

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A high level of hydrodenitrogenation (HDN) is required to achieve a desirable conversion of other hydroprocessing reactions. This results from a strong adsorption of nitrogen-containing compounds on catalytic sites that slows down the hydrogen activation process and hinders the adsorption of other reactants. Studies on model compounds and real feeds indicate that less than 50 ppm of nitrogen in the feed can poison catalytic sites. Kinetic studies determined adsorption constants of various nitrogen-containing compounds and concluded that at least four different catalytic sites are required to interpret experimental observations in contrast with a dual site site ffi concept, which only considered two sites. The advancements in experimental techniques allowed identification of products formed during very early stages of hydrodenitrogenation. These results confirmed that the removal of the amino group from saturated amines, as the last step in hydrodenitrogenation, is governed by the type of carbon to which the amino group is attached rather than the number of hydrogen atoms attached to carbon in a and b position to nitrogen Performance of conventional Co(Ni)Mo(W)/Al 2 O 3 catalysts during hydrodenitrogenation was enhanced by combination with various additives and by replacing the traditionally used g-Al 2 O 3 support with novel supports. Catalytic functionalities could be modified by using different precursors of active metals and varying conditions during preparation. Progress has been made in the development of catalysts possessing a high selectivity for hydrodenitrogenation. In this case, the nonconventional catalysts based on the carbides and nitrides of transition metals exhibited high activity and selectivity. Noble metal sulfides alone or supported on different supports were active for HDN as well. Feedstocks used for catalyst evaluation included model compounds and mixtures of model compounds as well as real feeds. The challenges in the development of catalysts for hydrodenitrogenation of heavy feeds containing asphaltenes and metals have been identified.In general, compared to Q, conversions were little affected by a methyl (Me) on the aromatic ring, while being lower for Me on the N-ring, except for 2-MeQ. It is evident that Me substitution in the 2-position had little effect on HDN over the NiMoP/Al 2 O 3 catalyst, whereas it actually enhanced the HDN rate over the CoMo/Al 2 O 3 catalyst. For both catalysts the HDN rate was suppressed in 6-MeQ and particularly in 3-MeQ and 4-MeQ. The distribution of N-containing intermediates was influenced by the ring substitution and the type of catalyst. This suggests that several factors influence the overall HDN mechanism of Qs. This should be kept in mind while analyzing differences in the networks proposed by different authors.The preceding discussion on the HDN of Q mostly referred to conventional catalysts. A number of studies on the HDN of Q were conducted over unconventional catalysts. For example, 3-and 4-MeQs were more reactive than Q over the unsupported Zr,...

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Section: Pyridinesmentioning

confidence: 99%

Section: Hydrodenitrogenation Of Petroleummentioning

confidence: 99%

Section: Iv11 Pyridinesmentioning

confidence: 99%

Section: E Furimsky and F E Massothmentioning

confidence: 99%

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Hydrodenitrogenation of Petroleum

Furimsky¹,

2005

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“…McIlvried et al 25 reported that the reaction is composed of three successive stages: hydrogenation of the pyridine ring, hydrogenolysis of the C-N bond forming pentylamine and denitrogenation to give the end products pentane and ammonia, where the hydrogenation is an essential step for achieving nitrogen removal. Anabtawi et al 26 used an integral flow reactor to study the hydrogenation of pyridine in gaseous phase, using Ni-W/γ-Al 2 O 3 as catalyst, finding that pyridine hydrogenation follows three stages. The first is saturation of the double bond of the pyridine to form piperidine, the second is disproportionation of the pyridine to produce ammonia and n-pentylpiperidine, and the third is the formation of n-pentane from the pentylpiperidine.…”

Section: Introductionmentioning

confidence: 99%

Tungsten and Rhenium as Hydrogenation Agents in the Hydrodenitrogenation of Pyridine Using Stacked Bed Catalyst Systems

Bassi

Villarroel

Llambías

et al. 2015

J. Chil. Chem. Soc.

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This study analyses the hydrodenitrogenation (HDN) of pyridine using a stacked bed catalyst system, composed of a first hydrogenating bed of Re/γ-Al 2 O 3 or W/γ-Al 2 O 3 , over a second bed of Ni-Re/γ-Al 2 O 3 (HDN bed). Using potentiometric methods, it can be seen that the Re/γ-Al 2 O 3 shows higher acidic strength than the W/γ-Al 2 O 3 . The results show that higher activity levels are obtained working with stacked bed systems compared to the separate catalysts. These results suggest that the incorporation of the catalyst Re/γ-Al 2 O 3 or W/γ-Al 2 O 3 beds would favour the formation of hydrogenated intermediary products, facilitating the removal of N-containing molecules via HDN on the Ni-Re/γ-Al 2 O 3 catalyst.

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ChemInform Abstract: HYDROGENATION OF PYRIDINE OVER NICKEL‐TUNGSTEN/ALUMINA CATALYST

Cited by 2 publications

References 1 publication

Hydrodenitrogenation of Petroleum

Hydrodenitrogenation of Petroleum

Tungsten and Rhenium as Hydrogenation Agents in the Hydrodenitrogenation of Pyridine Using Stacked Bed Catalyst Systems

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