New insight in the preparation of alumina supported hydrotreatment oxidic precursors: A molecular approach

Blanchard, Pascal; Lamonier, Carole; Griboval-Constant, Anne; Payen, Edmond

doi:10.1016/j.apcata.2007.01.018

Cited by 94 publications

(45 citation statements)

References 37 publications

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“…In addition, a decrease in PZC values was observed as Al/Ti ratio was increased, suggesting that incorporation of Ti induced superficial modifications in the supports. Since PZC of support influences the support-metal interaction [31], special attention should be paid to the conditions of impregnation. In this sense, a maximum concentration of anions species of W (HW 6 O 3À 20 and HW 6 O 20 OH ð Þ 5À 2 ) and a majority of positive surface charges exist simultaneously at pH 4 [32,33].…”

Section: Textural Propertiesmentioning

confidence: 99%

Deep Hydrodesulfurization of Dibenzothiophenes Over NiW Sulfide Catalysts Supported on Sol–Gel Titania–Alumina

et al. 2015

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This work showed that the use of Al 2 O 3 -TiO 2 as carriers has a positive effect on the activity of supported NiW catalysts in the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene carried out in a batch reactor at 320°C and total H 2 pressure of 5.5 MPa. Two Al 2 O 3 -TiO 2 mixed oxides with Al/Ti atomic ratios of 10 and 2 were synthesized by sol-gel method together with the pure Al 2 O 3 synthesized as reference support. For NiW/ Al 2 O 3 -TiO 2 and NiW/Al 2 O 3 catalysts, a metal load of 17 and 5.5 wt% of W and Ni were considered respectively. It was found that both Al 2 O 3 -TiO 2 -supported catalysts exhibited higher activity than alumina-supported one. The catalyst with a largest TiO 2 content (NiW/AT2) demonstrated to be 23 % more active with respect to NiW/Al 2 O 3 . Solids were characterized by temperature-programmed reduction (TPR), high resolution transmission electronic microscopy and X-ray photoelectronic spectroscopy (XPS) techniques. A decrease in support-metal interaction (from TPR) was observed when Ti content increased, which could lead to a higher amount of NiWS phase (from XPS). Besides, a slight increase in the slabs length in WS 2 was observed for titania-containing catalyst with respect to NiW/Al 2 O 3 , indicating that the dispersion can still be optimized. The atomic ratio Al/Ti = 2 of the NiW/Al 2 O 3 -TiO 2 catalyst proved to be a potential substitute for current catalysts for sulfur reduction in ultra-clean diesel.

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Section: Textural Propertiesmentioning

confidence: 99%

Deep Hydrodesulfurization of Dibenzothiophenes Over NiW Sulfide Catalysts Supported on Sol–Gel Titania–Alumina

et al. 2015

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“…New methods of preparation of the oxidic precursors have been developed in order to improve catalytic performance. Among them the use of Keggin or Anderson based heteropolyanions was proposed several years ago to prepare impregnating solutions instead of the classical ammonium heptamolybdate precursor [2,3]. Improvements have also been obtained through the addition of organic agents to the impregnating solution prepared with [4,5] or without [6] heteropolyanions.…”

Section: Introductionmentioning

confidence: 99%

Improvement of HDS catalysts through the modification of the oxidic precursor with 1,5-pentanediol: Gas phase sulfidation and thiophene conversion

Blanchard

Frizi

Mary

et al. 2016

Comptes Rendus. Chimie

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“…This Mo distribution is rather controlled by small interaction between Ni and Mo species and supports. Catalytic activities in dibenzothiophene hydrodesulfurization show that Mo 8 O 26 4-and Mo 7 O 24 2-ions closely interacting with [Ni 2? 6O 2-] ions are optimal for formation of a HDS active NiMoS phase.…”

Section: Discussionmentioning

confidence: 99%

“…Raman spectra of NiMo/ TiO 2 -Al 2 O 3 catalysts dried at 383 K are shown in Fig. 4 26 4-species on the support. This type of polymerization has been associated to net surface pH of support [23,24].…”

Section: Raman Spectroscopymentioning

confidence: 99%

Effect of TiO2–Al2O3 Sol–Gel Supports on the Superficial Ni and Mo Species in Oxidized and Sulfided NiMo/TiO2–Al2O3 Catalysts: Influence on Dibenzothiophene Hydrodesulfurization

2008

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The present work presents a comparative study of NiMo catalysts supported on sol-gel TiO 2 -Al 2 O 3 mixed oxides with 5 and 95 mol% content of Al 2 O 3 . The DRX and N 2 physisorption results showed that the sol-gel method allows preparation of TiO 2 -Al 2 O 3 mixed oxides possessing high superficial area and an amorphous TiO 2 structure. Results of f-potential showed that the net surface pH of the supports depends on their structure and composition. According to UV-Vis and Raman spectra obtained from the solids after impregnation, catalysts with high content of Al 2 O 3 showed Mo 7 O 24 2-and Mo 8 O 26 4-species displaying Mo-O-Mo stretching vibration modes. On the other hand, catalysts with high content of TiO 2 showed Mo 7 O 24 2-and Mo 8 O 26 4-species with vibration modes corresponding to terminal Mo=O t bonds. Therefore, it appears that impregnation of catalysts with a pH 9 solution allows a polymerization process of MoO 4 2-and [Ni 2? 4O 2-] solution species to Mo 8 O 26 4-and Mo 7 O 24 2-species with a close interaction with [Ni 2? 6O 2-] species. However, these species have low interaction with the support. Thus, composition of the support appears to be more important than net surface pH in order to obtain a better distribution of superficial Mo species. XPS results suggest a higher proportion of ''NiMoS'' phase on the TiO 2 rich support. The most active catalyst in the dibenzothiophene hydrodesulfurization was NiMo/TiO 2 -Al 2 O 3 with 5 mol% Al 2 O 3 . This suggests that Mo 7 O 24 2-and Mo 8 O 26 4-in combination with [Ni 2? 6O 2-] species produce a better Ni/(Ni ? Mo) ratio and NiMoS phase.

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New insight in the preparation of alumina supported hydrotreatment oxidic precursors: A molecular approach

Cited by 94 publications

References 37 publications

Deep Hydrodesulfurization of Dibenzothiophenes Over NiW Sulfide Catalysts Supported on Sol–Gel Titania–Alumina

Deep Hydrodesulfurization of Dibenzothiophenes Over NiW Sulfide Catalysts Supported on Sol–Gel Titania–Alumina

Improvement of HDS catalysts through the modification of the oxidic precursor with 1,5-pentanediol: Gas phase sulfidation and thiophene conversion

Effect of TiO2–Al2O3 Sol–Gel Supports on the Superficial Ni and Mo Species in Oxidized and Sulfided NiMo/TiO2–Al2O3 Catalysts: Influence on Dibenzothiophene Hydrodesulfurization

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