31P MAS NMR and Raman study of a Co(Zn)MoP/γ-Al2O3 HDS catalyst precursor containing triethylene glycol

Nicosia, Daniele; Prins, R.

doi:10.1016/j.jcat.2005.07.011

Cited by 31 publications

(16 citation statements)

References 13 publications

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“…Indeed, this resulted in catalyst materials with a much higher activity [11,25,26]. For the same reason, NH 4 + free solutions were used for impregnation, forcing the Co 2+ to act as a counter ion for Mo-anions [27,28]. From this point of view, the observed interaction of Co(II)-and Mo(VI)-complexes in simple AHM/Co(NO 3 ) 2 solutions is a remarkable finding.…”

Section: Discussionmentioning

confidence: 98%

On the interaction between Co- and Mo-complexes in impregnation solutions used for the preparation of Al2O3-supported HDS catalysts: A combined Raman/UV–vis–NIR spectroscopy study

2008

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Research has been carried out on the formation of cobalt (Co) and molybdenum (Mo) complexes in CoMo-solutions, which are used for the preparation of Al 2 O 3 -supported hydrodesulphurization (HDS) catalysts. Aim of this study was to obtain more insight into possible Co-Mo interactions and their implications for the impregnation process. For this purpose, Raman and UV-vis-NIR spectroscopy has been carried out on different impregnation solutions at various pH. In addition, multivariate curve resolution (MCR) of the Raman spectra has been applied to obtain information on the molecular structure and speciation of the different complexes present in solution. Furthermore, Raman microscopy and SEM-EDX were applied on Al 2 O 3 extrudates after impregnation, to obtain information on the distribution of the different metal-ions into the catalyst body as a function of time. It is demonstrated that an interaction between Co(II)-cations and different molybdate anions is indeed present in CoMosolutions. Two different CoMo-complexes are proposed in which Co 2+ -cations are bound to the outside of H x Mo 7 O 24 (6Àx)À complexes, resulting in a simultaneous transport of the Co and Mo metal-precursor complexes. Since Co acts as a promotor, a close interaction between Co and Mo in the final catalyst is of major importance for the catalytic activity. As such, the interaction should also be taken into account in the preparation of supported CoMo-HDS catalysts. #

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Section: Discussionmentioning

confidence: 98%

On the interaction between Co- and Mo-complexes in impregnation solutions used for the preparation of Al2O3-supported HDS catalysts: A combined Raman/UV–vis–NIR spectroscopy study

2008

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“…Meanwhile, those at higher wavenumbers were related to Mo=O bands. They were ascribed to Anderson species Al(OH)6Mo6O18 3− [40], whose presence suggested partial support dissolution during contact with the acidic Co-Mo-P impregnating solution (pH ~2.5). Considering the Mo/P ratio in those solutions (~2.0) and their pH, H2P2Mo5O23 4− anions (two PO4 tetrahedrons surrounded by five interconnected octahedral MoO6 species) could, very probably, be preferentially present [40,41].…”

Section: Raman Spectroscopymentioning

confidence: 99%

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

et al. 2019

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Alumina-lanthana (La at 1, 3, or 5 wt%) supports were prepared by sol-gel from Al alkoxide sol where La(NO3)3 was added. Annealed (550 °C) xerogels were characterized by N2 physisorption, thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy- energy dispersive spectroscopy (SEM-EDS), CO2-adsorption studied in IR region, Raman and ultraviolet-vis (UV-vis) spectroscopies. The texture of amorphous binary matrices of high La dispersion was adequate to applications in catalysts for middle distillates hydrodesulfurization (HDS). Generally, the amount and strength of surface basic sites increased with La content in solids. Mo (at 2.8 at. nm−2) and Co (at Co/(Co+Mo) = 0.3) were deposited over carriers by one-pot simultaneous impregnation in the presence of PO43− (P2O5/(NiO+MoO3) = 0.2 mass ratio). Calcined (400 °C) Co-Mo-P impregnated precursors had decreased basicity as to that of corresponding carriers, suggesting strong La-deposited species interaction. As La content in carriers increased Mo=O Raman stretching vibrations shifted to lower wave-numbers (949 to 935 cm−1) suggesting octahedral molybdates coordination change to tetrahedral. Although La at the lowest concentration (1 wt%) enhanced dibenzothiophene, HDS (~38% higher as to the Al2O3-supported formulation) desulfurization was significantly diminished at augmented content. Presence of hardly sulfidable tetrahedral Mo originated during impregnation at basic conditions in pores of La-modified carriers seemed to dictate observed behavior. Rare earth content in formulations enhanced selectivity to biphenyl.

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“…Two main distinct families of additives can be distinguished: glycol-type agents and chelating or complexing agents. The use of glycol-type agents was largely employed to optimize the preparation of MoS 2 -based catalysts [12,[17][18][19]. The main effect of glycol-type agents seems to be related to a redispersion of molybdic species at the catalyst surface leading to a higher proportion of less polymerized heteropolymolybdate species containing also cobalt, particularly for phosphorus-doped CoMo catalysts.…”

Section: Introductionmentioning

confidence: 99%

Maleic acid, an efficient additive for the activation of regenerated CoMo/Al2O3 hydrotreating catalysts

Bui

Geantet

Berhault

2015

Journal of Catalysis

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31P MAS NMR and Raman study of a Co(Zn)MoP/γ-Al2O3 HDS catalyst precursor containing triethylene glycol

Cited by 31 publications

References 13 publications

On the interaction between Co- and Mo-complexes in impregnation solutions used for the preparation of Al2O3-supported HDS catalysts: A combined Raman/UV–vis–NIR spectroscopy study

On the interaction between Co- and Mo-complexes in impregnation solutions used for the preparation of Al2O3-supported HDS catalysts: A combined Raman/UV–vis–NIR spectroscopy study

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

Maleic acid, an efficient additive for the activation of regenerated CoMo/Al2O3 hydrotreating catalysts

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