Reaction network of indole hydrodenitrogenation over NiMoS/γ-Al2O3 catalysts

Bunch, Abdu Y.; Zhang, Liping; Karakaş, Gürkan; Ozkan, Umit S.

doi:10.1016/s0926-860x(99)00270-7

Cited by 56 publications

(32 citation statements)

References 26 publications

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“…The C6 selectivity also increased in the HDN of both MPi and MPy, indicating higher temperature sensitivity for denitrogenation compared with (de)hydrogenation. This finding is similar to that reported by Bunch et al [33] and demonstrates that the denitrogenation reaction has a higher activation energy than the (de)hydrogenation reactions and thus is more sensitive to temperature. Moreover, the fact that the hydrogenation and dehydrogenation activities all increased with increasing temperature demonstrates that the system was still in the kinetic regime and not under thermodynamic control.…”

Section: Inhibition Effects On the Hdn Of Mpi And Mpysupporting

confidence: 92%

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Hydrodenitrogenation of 2-methylpyridine and its intermediates 2-methylpiperidine and tetrahydro-methylpyridine over sulfided NiMo/γ-Al2O3

Wang¹,

Liang²,

Prins³

2007

Journal of Catalysis

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Section: Inhibition Effects On the Hdn Of Mpi And Mpysupporting

confidence: 92%

“…Some studies have reported that H 2 S has a dual effect on the HDN reactions of pyridine, indole, and quinoline [31][32][33]. It slightly inhibits hydrogenation and dehydrogenation but markedly promotes C-N bond cleavage.…”

Section: Inhibition Effects On the Hdn Of Mpi And Mpymentioning

confidence: 99%

Hydrodenitrogenation of 2-methylpyridine and its intermediates 2-methylpiperidine and tetrahydro-methylpyridine over sulfided NiMo/γ-Al2O3

Wang¹,

Liang²,

Prins³

2007

Journal of Catalysis

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“…At 593 K, an increase in H 2 pressure from 0.7 to 7 MPa resulted in a significant increase in the production rate of ECH relative to EBz. The different observations may result from the markedly higher ratio of IN/OEAN in the feed used by these authors compared with that used by Zhang and Ozkan et al (162) and Bunch et al (163). A similar observation was made by Olivé et al (164).…”

Section: Iv21 Pyrrole (Pyr)mentioning

confidence: 58%

“…Using the sulfided NiMo/Al 2 O 3 catalyst, Zhang and Ozkan (162) and Bunch et al (163) observed that below 593 K and 0.8 MPa of H 2 , H 2 S (H 2 S/ H 2 ¼ 23 Â 10 23 ) promoted the overall conversion of IN; however, above 593 K this trend was reversed. The ECH/EBz ratio was higher in the absence of H 2 S. In the presence of H 2 S, the CNH of HIN to OEAN was enhanced.…”

Section: Iv21 Pyrrole (Pyr)mentioning

confidence: 99%

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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“…Pyrrole was selected as the reactant because organics with 5-member N-containing rings are the most common components in fuel. 7,8 Scheme 1. Strategy for Pt NP size control.…”

mentioning

confidence: 99%

Structure Sensitivity of Carbon−Nitrogen Ring Opening: Impact of Platinum Particle Size from below 1 to 5 nm upon Pyrrole Hydrogenation Product Selectivity over Monodisperse Platinum Nanoparticles Loaded onto Mesoporous Silica

et al. 2008

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The ability to control fundamental properties (e.g., particle size, surface structure, and metal-oxide interface) in order to design highly selective heterogeneous catalysts would greatly reduce energy intensive separations. Particle size dependence (i.e., structure sensitivity) upon selectivity can now be examined with well defined nanoparticles (NPs) because of advances in synthetic chemistry. Colloidal chemistry has provided means for synthesizing monodisperse Pt NPs as small as ~2 nm. 1,2 Using a dendrimer templated approach, Pt NPs smaller than 1 nm -a new size regime for studying size induced effects in heterogeneous catalysis -can be synthesized (Scheme 1). 3,4 In this contribution, we report that ring opening for pyrrole hydrogenation is distinctly different for Pt NPs smaller than 2 nm. This insight has not been demonstrated for hydrogenation of cyclic heteroatom bonds to the best of our knowledge. This finding adds fundamental insight into hydrodenitrogenation (HDN) chemistry, which is important for fuel processing and involves removal of N-containing organics. Advances in HDN catalysis are needed to meet new fuel quality regulations because N-containing organics inhibit hydrodesulfurization (HDS) through competitive adsorption 5 and poison acid catalysts 6 , which are used for downstream processing and as supports for HDS catalysts. Pyrrole was selected as the reactant because organics with 5-member N-containing rings are the most common components in fuel. 7,8 Scheme 1. Strategy for Pt NP size control.Pt NPs between 0.8 and 5.0 nm were synthesized by two techniques. For ultrasmall NPs, fourth generation hydroxyl terminated polyamidoamine (PAMAM) dendrimers were used as the templating and capping agent. 4 Synthesis and characterization of Pt 20 and Pt 40 NPs (subscripts denote the average number of metal atoms per NP) have been described. 4,9 The average number of metal atoms per NP is controlled by the Pt ion to dendrimer ratio. Due to difficulties in obtaining accurate size distributions from TEM, sizes were calculated from the average number of metal ions added per dendrimer, which was proven as accurate by X-ray absorption studies. 10 Sizes of Pt 20 and Pt 40 NPs were calculated to be 0.8 and 1.0 nm, respectively. 11 A TEM image ( Figure 1a) of the Pt 60 NPs showed that the Pt size was 1.95 ± 0.27 nm. This size is larger than that expected from the Pt ion to dendrimer ratio and is caused by formation of interdendrimer complexes because the number of Pt atoms per dendrimer approached the number (62) of available internal tertiary amine groups. Pt NPs (1.5, 2.9, and 5.0 nm) were synthesized with polyvinylpyrolidone (PVP) by existing procedures 1,2 with a TEM image in Figure 1b Pt NPs were loaded onto SBA-15 silica (TEM image in Figure 1c for 1.5 nm Pt NPs). For PVP capped NPs, H 2 chemisorption indicated that Pt dispersion decreased as the NP size increased (Table S1). However, reliable dispersion measurements could not be obtained by this method for dendrimer encapsulated Pt NPs so ethylene hydr...

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Reaction network of indole hydrodenitrogenation over NiMoS/γ-Al2O3 catalysts

Cited by 56 publications

References 26 publications

Hydrodenitrogenation of 2-methylpyridine and its intermediates 2-methylpiperidine and tetrahydro-methylpyridine over sulfided NiMo/γ-Al2O3

Hydrodenitrogenation of 2-methylpyridine and its intermediates 2-methylpiperidine and tetrahydro-methylpyridine over sulfided NiMo/γ-Al2O3

Hydrodenitrogenation of Petroleum

Structure Sensitivity of Carbon−Nitrogen Ring Opening: Impact of Platinum Particle Size from below 1 to 5 nm upon Pyrrole Hydrogenation Product Selectivity over Monodisperse Platinum Nanoparticles Loaded onto Mesoporous Silica

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