Characterization and evaluation of ZrO2 supported hydrotreating catalysts

Maity, Samir; Rana, Mohan S.; Srinivas, B.; Bej, Shyamal K.; Dhar, G. Murali; Rao, T. Siva

doi:10.1016/s1381-1169(99)00311-8

Cited by 132 publications

(59 citation statements)

References 20 publications

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“…The peaks at 506.1, 596.4, and 747.6 cm −1 are attributed to Zr−O stretching vibrations. 45,46 The peak at 506.1 cm −1 also indicates the existence of both tetragonal and monoclinic zirconia. 47 As shown in Figure 1d, the SEM mapping identifies the elemental distribution of zirconium (Zr), oxygen (O), and carbon (C) in the ZCNs.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

Zirconia (ZrO₂) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Luo

et al. 2016

ACS Appl. Mater. Interfaces

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To use zirconia (ZrO 2 ) as an efficient environmental adsorbent, it can be impregnated on a support to improve its physical properties and lower the overall cost. In this study, ZrO 2 embedded in carbon nanowires (ZCNs) is fabricated via an electrospinning method to remove arsenic (As) from water. The maximum adsorption capacity values of As(III) and As(V) on the ZCNs are 28.61 and 106.57 mg/g, respectively, at 40°C. These capacities are considerably higher than those of pure ZrO 2 (2.56 and 3.65 mg/g for As(III) and As(V), respectively) created using the same procedure as for the ZCNs. Meanwhile, the adsorption behaviors of As(III) and As(V) on the ZCNs are endothermic and pH dependent and follow the Freundlich isotherm model and pseudo-first-order kinetic model. Both As(III) and As(V) are chemisorbed onto the ZCNs, which is confirmed by a partial density of state (PDOS) analysis and Dubinin−Radushkevich (D-R) model calculations. Furthermore, the ZCNs also possess the capability to enhance or catalyze the oxidation process of As(III) to As(V) using dissolved oxygen. This result is confirmed by a batch experiment, XPS analysis and Mulliken net charge analysis. Density functional theory (DFT) calculations indicate the different configurations of As(III) and As(V) complexes on the tetragonal ZrO 2 (t-ZrO 2 )(111) and monoclinic ZrO 2 (m-ZrO 2 )(111) planes, respectively. The adsorption energy (E ad ) of As(V) is higher than that of As(III) on both the tZrO 2 (111) and m-ZrO 2 (111) planes (3.38 and 1.90 eV, respectively, for As(V) and 0.37 and 0.12 eV, respectively, for As(III)).

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Section: ■ Results and Discussionmentioning

confidence: 98%

Zirconia (ZrO₂) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Luo

et al. 2016

ACS Appl. Mater. Interfaces

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“…Therefore, the first peak at the low temperature region is attributed to the partial reduction of octahedral Mo 6+ species from Mo 6+ to Mo 4+ and the reduction of small crystalline MoO 3 [21,22]. Meanwhile, the second peak at the high temperature region is assigned to the reduction of the tetrahedral Mo 6+ species [23,24], and the further reduction of MoO 2 from Mo 4+ to Mo 0 [17].…”

Section: H 2 -Tpr Analysismentioning

confidence: 98%

Effect of Citric Acid on MoO3/Al2O3 Catalysts for Sulfur-Resistant Methanation

Dajun

Wang

et al. 2017

Catalysts

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A series of MoO 3 /Al 2 O 3 catalysts with different amounts (molar ratio of CA/Mo = 0, 1, 1.5, and 2) of citric acid (CA) prepared by simultaneous impregnation were evaluated for sulfur-resistant methanation. Based on the evaluation results, catalytic activity increased accompanied with the rise of citric acid amount. Combine with the analysis of N 2 -physisorption, XRD, H 2 -TPR, XPS, and TEM, the catalyst saturated loading capacity improved, resulting in increasing dispersion of Mo species on Al 2 O 3 surface clearly. According to H 2 -TPR result, the Mo oxide precursors can be more easily sulfureted when citric acid is added. Moreover, based on the Raman analysis, increasingly tetrahedrally coordinated Mo 6+ species with high methanation performance are generated after citric acid treatment. These factors probably together accelerate MoO 3 /Al 2 O 3 catalytic activity growth for methanation.

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“…Usually the supports are alumina or silica, but considerable interest is now devoted to other supports such as TiO 2 , 11 Nb 2 O 5 , 12 and ZrO 2 . 6,10,[13][14][15] Zirconia is a very interesting material because of its thermal stability, its mechanical properties, and its basic, acidic, reducing, and oxidizing surface properties. Therefore, it is attracting interest in catalysis as a support material as well as a catalyst.…”

Section: Introductionmentioning

confidence: 99%

“…So far, however, supported molybdenum oxide catalysts have been mainly on alumina 19 and silica, 20 and only some work was studied for the ZrO 2 support. [13][14][15] Moreover, there is no systematic study using a variety of instruments, although some limited work by Raman spectroscopy and X-ray diffraction was reported. [13][14][15] This paper describes spectroscopic studies on ZrO 2 modified with MoO 3 and catalytic activity for acid catalysis.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Studies on ZrO₂Modified with MoO₃and Activity for Acid Catalysis

2003

Bulletin of the Korean Chemical Society

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Zirconia modified with MoO 3 was prepared by impregnation of powdered Zr(OH) 4 with ammonium heptamolybdate aqueous solution followed by calcining in air at high temperature. Spectroscopic studies on prepared catalysts were performed by using FTIR, Raman, XRD, and DSC and by measuring surface area. Upon the addition of molybdenum oxide to zirconia up to 15 wt%, the specific surface area increased in proportion to the molybdate oxide content, while acidity measured by irreversible chemisorption of ammonia exhibited a maximum value at 3 wt% of MoO 3 . Since the ZrO 2 stabilizes the molybdenum oxide species, for the samples equal to or less than 30 wt%, molybdenum oxide was well dispersed on the surface of zirconia and no phase of crystalline MoO 3 was observed at any calcination temperature above 400 o C. The catalytic activities for cumene dealkylation were roughly correlated with the acidity of catalysts measured by ammonia chemisorption method, while the catalytic activities for 2-propanol dehydration were not correlated with the acidity because weak acid sites are necessary for the reaction.

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Characterization and evaluation of ZrO2 supported hydrotreating catalysts

Cited by 132 publications

References 20 publications

Zirconia (ZrO₂) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Zirconia (ZrO₂) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Effect of Citric Acid on MoO3/Al2O3 Catalysts for Sulfur-Resistant Methanation

Spectroscopic Studies on ZrO₂Modified with MoO₃and Activity for Acid Catalysis

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Characterization and evaluation of ZrO2 supported hydrotreating catalysts

Cited by 132 publications

References 20 publications

Zirconia (ZrO2) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Zirconia (ZrO2) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Effect of Citric Acid on MoO3/Al2O3 Catalysts for Sulfur-Resistant Methanation

Spectroscopic Studies on ZrO2Modified with MoO3and Activity for Acid Catalysis

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Product

Resources

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Zirconia (ZrO₂) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Zirconia (ZrO₂) Embedded in Carbon Nanowires via Electrospinning for Efficient Arsenic Removal from Water Combined with DFT Studies

Spectroscopic Studies on ZrO₂Modified with MoO₃and Activity for Acid Catalysis