Effect of boron addition on the surface structure of Co-Mo/Al2O3 catalysts

Usman, .; Kubota, Takeshi; Hiromitsu, Ichiro; Okamoto, Yasuaki

doi:10.1016/j.jcat.2007.01.010

Cited by 38 publications

(25 citation statements)

References 32 publications

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“…We found that the temperature dependency of the observed » is rationally fitted by using the theoretical eq 3 as shown in Figure 20 (¡ = 0.84 0.97), suggesting that the structure of the CoMoS sites is represented as a Co dinuclear cluster on the MoS 2 edge. 134 It was shown that CoMo/Al 2 O 3 catalysts prepared by conventional impregnation (without calcination to avoid the formation of paramagnetic Co 2+ species in a CoAl 2 O 4 -like phase) exhibit an antiferromagnetic property described by eq 3, 136 substantiating the validity of our approach by use of the CVD catalysts to practical HDS catalysts. While the magnetic susceptibility of CVD-CoS/Al 2 O 3 showed some contribution of antiferromagnetic components, the magnetic susceptibility » of sulfided CoS/Al 2 O 3 prepared by impregnation obeyed a CurieWeiss law.…”

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confidence: 52%

“…Co K-edge XANES results provided further evidence to the conclusion. 136 As shown in Figure 32, the activity of CVD-CoMo/B-Al 2 O 3 for the HDS of thiophene significantly increases with the increase of boron content up to about 0.6 wt % B and decreases with further addition of boron. The support B-Al 2 O 3 was found to show only marginal activity comparable to that of Al 2 O 3 for the HDS under the present reaction conditions.…”

Section: 153mentioning

confidence: 89%

“…The magnetic properties of Co in CVD-CoMo/B-Al 2 O 3 (0.6% B) showed a typical antiferromagnetic behavior characteristic to the CoMoS structure. 136 It is hence concluded that the CoMoS structure is selectively formed on MoS 2 /B-Al 2 O 3 by CVD. Co K-edge XANES results provided further evidence to the conclusion.…”

Section: 153mentioning

confidence: 96%

“…Instead, we propose an "epitaxial ad-cluster" model illustrated in Figure 28 to describe the structure of the CoMoS structure, in which model dinuclear Co sulfide clusters are anchored or coordinated to the edge of MoS 2 particles. 143 On the basis of the ad-cluster model, preferential formation of antiferromagnetic dinuclear Co sulfide clusters is readily understood irrespective of the coverage of Co on the edge, 136 since monomeric Co sulfide species in a square-pyramidal configuration is energetically unfavorable as shown by Byskov et al…”

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confidence: 99%

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Novel Molecular Approaches to the Structure–Activity Relationships and Unique Characterizations of Co–Mo Sulfide Hydrodesulfurization Catalysts for the Production of Ultraclean Fuels

Okamoto¹

2013

Bulletin of the Chemical Society of Japan

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Hydrodesulfurization (HDS) catalysts have been extensively used worldwide in refineries to protect the environment. The present Account reviews our recent studies to establish the structureactivity relationships of HDS catalysts on a molecular level. We have developed two molecular approaches to this issue; a molecular cluster approach using intrazeolite Mo sulfide and CoMo binary sulfide clusters possessing well-defined structures and a CVD-CoMo sulfide designed catalyst approach in which Co is exclusively accommodated in the CoMoS structure, the active sites of HDS catalysts. It is revealed that the Co sites of intrazeolite thiocubane-type [Co 2 Mo 2 S 6 ] clusters play a pivotal role in HDS reaction and that the MoMo atomic distance of Mo 2 S 4 dinuclear clusters determines the HDS activity. Designed CVDCoMo catalysts supported on refractory oxides have been successfully prepared by CVD using [Co(CO) 3 NO] as a precursor of Co. Combined with magnetic properties and XAFS, it is concluded that the CoMoS structure is dinuclear Co sulfide clusters located on the edge of MoS 2 nanoparticles. It is shown that the intrinsic activity of the CoMoS structure substantially depends on the MoS 2 -edge where it is located. The effects of support and additives are discussed on the basis of the intrinsic activity. Both MoS 2 support interactions and reaction or sulfidation conditions elucidate the local structure and intrinsic activity of the CoMoS structure. It is demonstrated that the CVD technique using [Co(CO) 3 NO] provides unique characterization methods of HDS catalysts.

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supporting

confidence: 52%

Section: 153mentioning

confidence: 89%

Section: 153mentioning

confidence: 96%

mentioning

confidence: 99%

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Novel Molecular Approaches to the Structure–Activity Relationships and Unique Characterizations of Co–Mo Sulfide Hydrodesulfurization Catalysts for the Production of Ultraclean Fuels

Okamoto¹

2013

Bulletin of the Chemical Society of Japan

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“…The United States Environmental Protection Agency (EPA) has introduced regulations aimed at lowering the amount of sulphur and nitrogen content in diesel fuels from the current 500 to 15 ppm wt, and in gasoline from 300 to 30 ppm wt by 2006 [1] and to 10 ppm wt and less, around 2009 [2,3].Therefore, a great deal of research in the field of heterogeneous catalysis is being devoted to the hydrodesulphurisation (HDS) of petroleum fractions for the production of ultra clean fuels [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Hydrodesulphurisation activity of CoMo catalyst supported on multi wall carbon nanotube: sulphur species study

Khorami¹,

Kalbasi²

2011

Journal of Experimental Nanoscience

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Multi wall carbon nanotube (MWCNT) supported CoMo catalyst was prepared and hydrodesulphurisation (HDS) activity of naphtha was evaluated in a fixed bed down flow reactor. Activity test experiments were conducted at a temperature of 310 C, pressure of 15 bar and liquid hourly space velocity of 4/h. The conditions were close to those of industrial practice. The structure of the MWCNT was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and accelerated surface area and porosity system (ASAP). The catalyst was characterised by X-ray diffraction, SEM, energy dispersive X-ray, inductively coupled plasma optical emission spectrometry, TEM and ASAP. Also for sulphur species study, naphtha feed and product were analysed by gas chromatography-sulphur chemiluminescence detection. Catalytic activity test indicated that MWCNT is a suitable support for HDS catalyst. Sulphur conversion of the catalyst was 88%. Also sulphur species comparison showed that all the sulphur types were converted.

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Hydrodesulfurization Properties of Nickel Phosphide on Boron‐treated Alumina Supports

et al. 2020

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The deep hydrodesulfurization (HDS) properties of nickel phosphide (Ni 2 P) on boron-modified alumina (xBÀ Al 2 O 3) supports having different B contents have been investigated. Ni 2 P precursors were prepared on the xBÀ Al 2 O 3 supports using hypophosphite (-hypo) or phosphate (-phos) as the P source and were subsequently reduced in flowing hydrogen. The 4,6dimethyldibenzothiophene HDS activities and turnover frequencies of the Ni 2 P/xBÀ Al 2 O 3 catalysts showed a strong dependence on B loading, with a maximum observed for the hypophosphite-and phosphate-based Ni 2 P/BÀ Al 2 O 3 catalysts corresponding to 0.8 wt % and 1.2 wt % B loadings, respectively. Based on XPS and IR spectral measurements, the optimal B loadings corresponded to~20 % B 2 O 3 coverage of the γ-Al 2 O 3 support and coincided with removal of the most basic hydroxyl groups on the alumina surface. At 573 K, a Ni 2 P/0.8BÀ Al 2 O 3-hypo catalyst was 2.5 times more active than a B-free Ni 2 P/Al 2 O 3-hypo catalyst, while a Ni 2 P/1.2BÀ Al 2 O 3-phos catalyst was 8.6 times more active than a B-free Ni 2 P/Al 2 O 3-phos catalyst. Overall, the hypophosphite-based Ni 2 P/BÀ Al 2 O 3 catalysts exhibited higher HDS activities than the phosphate-based Ni 2 P/BÀ Al 2 O 3 catalysts, in part due to smaller Ni 2 P particle sizes. The optimized catalysts, Ni 2 P/0.8BÀ Al 2 O 3-hypo and Ni 2 P/1.2BÀ Al 2 O 3-phos , were more active than a sulfided NiÀ Mo/Al 2 O 3 catalyst.

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Effect of boron addition on the surface structure of Co-Mo/Al2O3 catalysts

Cited by 38 publications

References 32 publications

Novel Molecular Approaches to the Structure–Activity Relationships and Unique Characterizations of Co–Mo Sulfide Hydrodesulfurization Catalysts for the Production of Ultraclean Fuels

Novel Molecular Approaches to the Structure–Activity Relationships and Unique Characterizations of Co–Mo Sulfide Hydrodesulfurization Catalysts for the Production of Ultraclean Fuels

Hydrodesulphurisation activity of CoMo catalyst supported on multi wall carbon nanotube: sulphur species study

Hydrodesulfurization Properties of Nickel Phosphide on Boron‐treated Alumina Supports

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