Mechanisms of hydrodesulfurization and hydrodenitrogenation

Prins, R.; Egorova, Marina; Röthlisberger, A.; Zhao, Yonggang; Sivasankar, N.; Kukula, Pavel

doi:10.1016/j.cattod.2005.10.008

Cited by 127 publications

(77 citation statements)

References 37 publications

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“…The table lists (DMBCH). The DMBP has been considered as the product from direct desulfurization (DDS) pathway, whereas the MCHT and DMBCH from hydrogenation (HYD) pathway [72,73]. A previous study using similar condition also pointed out that DMBP cannot be produced by a secondary dehydrogenation pathway as the parallel dehydrogenation of tetralin to naphthalene did not occur [42].…”

Section: Infrared Spectroscopy Of Adsorbed Comentioning

confidence: 99%

Nature of active sites in Ni2P hydrotreating catalysts as probed by iron substitution

Zhao

Oyama

Freund

et al. 2015

Applied Catalysis B: Environmental

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A series of NiFeP/SiO 2 catalysts with different Ni:Fe molar ratios (1:0, 3:1, 1:1, 1:3, 0:1) was investigated for the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene.The Fe component is a good probe for active sites because Ni 2 P and Fe 2 P adopt the same hexagonal crystal structure, yet Fe 2 P is completely inactive for HDS. X-ray diffraction analysis and FTIR spectroscopy of adsorbed CO indicated the formation homologous alloys. At 3.1 MPa and 613 K (340 o C) the activity of the alloys was similar to that of Ni 2 P, which was very high. There was also unprecedented selectivity towards direct desulfurization (DDS). A reconstruction of the NiFe phase occurred to expose more Ni sites, likely driven by the formation of surface Ni-S bonds as observed by EXAFS. The analysis showed that Ni(2) pyramidal sites responsible for hydrogenation were largely replaced by Fe. This left behind Ni(1) tetrahedral sites which favor DDS and explains the reactivity results.

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Section: Infrared Spectroscopy Of Adsorbed Comentioning

confidence: 99%

Nature of active sites in Ni2P hydrotreating catalysts as probed by iron substitution

Zhao

Oyama

Freund

et al. 2015

Applied Catalysis B: Environmental

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“…For Ni(Co)-MoS 2 catalysts only TH-DBT can be observed [30]. Therefore, the catalytic selectivity determined from the ratio between HYD and DDS can be approximated by the following equation:…”

Section: Catalytic Hds Activity and Selectivitymentioning

confidence: 99%

“…According to the study of Prins et al [30] the two HDS pathways are determined by the orientation of the adsorbed DBT molecules with respect to the catalysts surface. The DDS pathway occurs through r adsorption via the sulfur atom and HYD through p adsorption via the aromatic system.…”

Section: Catalytic Hds Activity and Selectivitymentioning

confidence: 99%

SBA-15 as Support for MoS2 and Co-MoS2 Catalysts Derived from Thiomolybdate Complexes in the Reaction of HDS of DBT

et al. 2007

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Molybdenum sulfide and cobalt-molybdenum sulfide catalysts supported on mesoporous SBA-15 were prepared by thermal decomposition of ammonium thiomolybdate (ATM). SBA-15 was synthesized at 353 K and 413 K to obtain pore diameters of about 6 and 9 nm, respectively. The (Co)-MoS 2 /SBA-15 catalysts were characterized with X-ray diffraction (XRD), N 2 -physisorption and high-resolution transmission electron microscopy (HRTEM). HRTEM images give evidence for the presence of a poorly dispersed MoS 2 phase with long MoS 2 slabs and a pronounced MoS 2 stacking. The catalytic performance in the hydrodesulfurization (HDS) reaction of dibenzothiophene (DBT) was examined at T = 623 K and P = 3.4 MPa. The Co-MoS 2 /SBA-15 materials show a relatively high catalytic activity with a strong preference for the direct desulfurization (DDS) pathway. This is an interesting result in view of the significant stacking of MoS 2 particles and the size of the slabs. The generation of the catalytically active CoMoS phase and a large number of coordinately unsaturated sites (CUS) may explain the high performance of Co promoted MoS 2 /SBA-15 catalysts in the HDS reaction.A confinement effect of the mesoporous channels of SBA-15 is observed for the unpromoted MoS 2 /SBA-15 catalysts. SBA-15 with 9 nm channel diameter with 11 wt.% Mo loading shows a higher selectivity for the hydrogenation pathway than SBA-15 with 6 nm channel and 16 wt.% Mo loading.

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“…Recent studies have shown that the catalytic activity and selectivity of mesoporous CoMo/γ-Al2O3 and NiMo/γ-Al2O3 sulfide catalysts in the hydrotreating of petroleum-and coal-derived oils are not only associated with surface fine structures of Co-and Ni-incorporated MoS2-like slabs as the catalytically active sites, but also strongly influenced by the spatial location of heteroatom-containing compounds, such as H2S or amines, competitively adsorbed on the catalytically active sites [25,26,[28][29][30][31][32][33]. In the HDS of DBT and DMDBT, it is generally agreed that the catalytically active sites for the DDS pathway are associated with the CUS regions at the edges or corners of Co-and Ni-incorporated MoS2-like slabs, so-called the Co(Ni)-Mo-S structures, while those for the HYD pathway are related to the brim sites, which exhibit metal-like character [25,26]. In the upgrading of model diesel oil A over the mesoporous CoMo/γ-Al2O3 sulfide catalyst, there is no doubt that small Co-incorporated MoS2-like slabs with high stacking numbers are highly efficient in the HDS of DBT toward the DDS product, which is catalyzed by the Co-Mo-S structures at the edges or corners.…”

Section: Hydrotreating Model Diesel Oilsmentioning

confidence: 99%

“…To understand the catalytic behavior of the mesoporous sulfide catalysts in the hydrotreating of model diesel oils A-D, the possible reaction pathways for HDS, HYD, HDO, and HDN are illustrated in Scheme 2 [25][26][27]. In the HDS of DBT, biphenyl is formed by the direct desulfurization (DDS) pathway, whereas cyclohexylbenzene and cyclopentylmethylbenzene are formed by the HYD and subsequent isomerization/desulfurization pathway.…”

Section: Hydrotreating Model Diesel Oilsmentioning

confidence: 99%

Co-Processing of Jatropha-Derived Bio-Oil with Petroleum Distillates over Mesoporous CoMo and NiMo Sulfide Catalysts

et al. 2018

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Abstract:The co-processing of an unconventional type of Jatropha bio-oil with petroleum distillates over mesoporous alumina-supported CoMo and NiMo sulfide catalysts (denoted CoMo/γ-Al 2 O 3 and NiMo/γ-Al 2 O 3 ) was studied. Either a stainless-steel high-pressure batch-type reactor or an up-flow fixed-bed reaction system was used under severe reaction conditions (330-350 • C and 5-7 MPa), similar to the conditions of the conventional diesel hydrodesulfurization (HDS) process. To understand the catalytic performance of the mesoporous sulfide catalysts for co-processing, we prepared two series of oil feedstocks. First, model diesel oils, consisting of hydrocarbons and model molecules with various heteroatoms (sulfur, oxygen, and nitrogen) were used for the study of the reaction mechanisms. Secondly, low-grade oil feedstocks, which were prepared by dissolving of an unconventional type of Jatropha bio-oil (ca. 10 wt %) in the petroleum distillates, were used to study the practical application of the catalysts. Surface characterization by gas sorption, spectroscopy, and electron microscopy indicated that the CoMo/γ-Al 2 O 3 sulfide catalyst, which has a larger number of acidic sites and coordinatively unsaturated sites (CUS) on the mesoporous alumina framework, was associated with small Co-incorporated MoS 2 -like slabs with high stacking numbers and many active sites at the edges and corners. In contrast, the NiMo/γ-Al 2 O 3 sulfide catalyst, which had a lower number of acidic sites and CUS on mesoporous alumina framework, was associated with large Ni-incorporated MoS 2 -like slabs with smaller stacking numbers, yielding more active sites at the brims and corresponding to high hydrogenation (HYD) activity. Concerning the catalytic performance, the mesoporous CoMo/γ-Al 2 O 3 sulfide catalyst with large CUS number was highly active for the conventional diesel HDS process; unfortunately, it was deactivated when oxygen-and nitrogen-containing model molecules or Jatropha bio-oil were present in the oil feedstock. In contrast, the mesoporous NiMo/γ-Al 2 O 3 sulfide catalyst, which had a high HYD activity and low affinity for heteroatoms, was efficient in the simultaneous removal of those heteroatoms from model diesel oils, and, in particular, Jatropha bio-oil co-fed with petroleum distillates. This could allow the production of a drop-in diesel-like fuel, which would be a greener fuel and reduce the CO 2 emissions and hazardous exhaust gases produced by the transport sector, reducing the burden on the environment.

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Mechanisms of hydrodesulfurization and hydrodenitrogenation

Cited by 127 publications

References 37 publications

Nature of active sites in Ni2P hydrotreating catalysts as probed by iron substitution

Nature of active sites in Ni2P hydrotreating catalysts as probed by iron substitution

SBA-15 as Support for MoS2 and Co-MoS2 Catalysts Derived from Thiomolybdate Complexes in the Reaction of HDS of DBT

Co-Processing of Jatropha-Derived Bio-Oil with Petroleum Distillates over Mesoporous CoMo and NiMo Sulfide Catalysts

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