Application of lanthanum to pseudo-boehmite and ?-Al2O3

Tijburg, I. I. M.; Geus, J.W.; Zandbergen, H.W.

doi:10.1007/bf00551900

Cited by 7 publications

(11 citation statements)

References 5 publications

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“…The natural pH of γ-alumina particles was found to be at 9.1; the zeta potential at this point is -23 mV. This iep and the natural pH values are in good agreement with previous measurements in the literature which were 7.7 -7.9 and 9.0 -9.2 respectively (Binner & McDermott, 2006;Agrafiotis & Tsetsekou, 2000;Nowack et al, 1996;Tijburg et al, 1991). As the slurry pH gets close to the iep, the van der Waals attraction forces between particles become dominant, leading to particle aggregation and less stabilisation.…”

Section: Zeta Potential Measurementssupporting

confidence: 90%

“…However, the ESA measurements close to the iep should be treated with caution based on the minimal stabilisation in the slurry (Greenwood, 2003). The optimal stabilisation of particles was achieved at pH of 4 and this is in accordance with the values in the literature in the range of 3.8 -4.5 (Binner & McDermott, 2006;Agrafiotis & Tsetsekou, 2000;Nowack et al, 1996;Tijburg et al, 1991). This pH value corresponds to a zeta potential of +41 mV.…”

Section: Zeta Potential Measurementssupporting

confidence: 85%

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Particle Characterisation and Grinding Behaviour of Gamma-Alumina Slurries Prepared in a Stirred Media Mill

Adegbite¹

2012

JMSR

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This paper investigates gamma-alumina slurry preparation in a stirred media mill to develop protocols for the characterisation of slurries for coating onto monolithic catalyst supports. The relationship between the pH and the zeta potential of particles is determined. The gamma–alumina particles are found to be optimally stabilised at a pH of 4 and zeta potential of +41 mV. The grinding behaviour of gamma-alumina particles inside the mill is determined in terms of the number of stress events (SN), stress energy (SE) and the specific energy (E_m,p). The visualisation of the particles at different stages of milling is done by scanning electron microscope (SEM). The results show that finer particles are produced by increasing milling duration from 0 – 240 min due to an increase in SN and that the use of smaller grinding media inside the mill produced finer particles due to an efficient consumption of E_m,p.

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Section: Zeta Potential Measurementssupporting

confidence: 90%

Section: Zeta Potential Measurementssupporting

confidence: 85%

Particle Characterisation and Grinding Behaviour of Gamma-Alumina Slurries Prepared in a Stirred Media Mill

Adegbite¹

2012

JMSR

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“…34 Our previous work 15 shows the formation of atomically dispersed rhodium after calcination at 773 K when samples are impregnated with the rhodium acetate precursor: the promoted catalysts have exclusively atomically dispersed rhodium and Rh/Al 2 O 3 also contains small clusters. 12,14,[37][38][39][40][41] The stabilization of alumina impacts in turn the dispersion of rhodium, inhibiting coalescence. Grunwaldt et al 25 observed a significant increase in the contribution of the Rh-Rh shell in Rh/Al 2 O 3 catalysts after reduction at 773 K in comparison with a heating treatment under helium, indicating the increase in size of the metal particles under a reductive atmosphere.…”

Section: The Esi †) Similar Values As the Ones Reported Inmentioning

confidence: 99%

Atomically dispersed rhodium on a support: the influence of a metal precursor and a support

Duarte¹,

Safonova²,

Krumeich³

et al. 2014

Phys. Chem. Chem. Phys.

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The influence of the support type and the metal precursor on the dispersion of rhodium after calcination and reduction was determined. The combination of electron microscopy and X-ray absorption analysis allowed the quantification of the amount of atomically dispersed rhodium in the samples. Higher amounts of atomically dispersed rhodium atoms are obtained when metal impregnation is performed with a rhodium acetate precursor in comparison to a rhodium chloride precursor over supports of the same composition. The stability of rhodium is improved with the addition of promoters; the co-presence of samaria and ceria in the support and metal impregnation with a rhodium acetate precursor leads to the highest amount of atomically dispersed rhodium remaining after reductive treatment at 773 K.

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“…Previous reports on Ln-doping of alumina have generally been conducted at doping concentrations of 0.5–5 wt%202122232425. The formation of a new phase, LnAlO 3 or Ln 2 O 3 , is observed in previously reported cases, which complicates understanding of the role Ln-doping plays on structure and phase transition of the alumina lattice2627. This also makes it intriguing to assess the role of other Ln-elements as “structural promoters” due to their phase transformation delays and resulting effects on the structure of doped alumina.…”

mentioning

confidence: 99%

Structural Effects of Lanthanide Dopants on Alumina

Patel

Blair

Douglas

et al. 2017

Sci Rep

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Lanthanide (Ln3+) doping in alumina has shown great promise for stabilizing and promoting desirable phase formation to achieve optimized physical and chemical properties. However, doping alumina with Ln elements is generally accompanied by formation of new phases (i.e. LnAlO3, Ln2O3), and therefore inclusion of Ln-doping mechanisms for phase stabilization of the alumina lattice is indispensable. In this study, Ln-doping (400 ppm) of the alumina lattice crucially delays the onset of phase transformation and enables phase population control, which is achieved without the formation of new phases. The delay in phase transition (θ → α), and alteration of powder morphology, particle dimensions, and composition ratios between α- and θ-alumina phases are studied using a combination of solid state nuclear magnetic resonance, electron microscopy, digital scanning calorimetry, and high resolution X-ray diffraction with refinement fitting. Loading alumina with a sparse concentration of Ln-dopants suggests that the dopants reside in the vacant octahedral locations within the alumina lattice, where complete conversion into the thermodynamically stable α-domain is shown in dysprosium (Dy)- and lutetium (Lu)-doped alumina. This study opens up the potential to control the structure and phase composition of Ln-doped alumina for emerging applications.

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Application of lanthanum to pseudo-boehmite and ?-Al2O3

Cited by 7 publications

References 5 publications

Particle Characterisation and Grinding Behaviour of Gamma-Alumina Slurries Prepared in a Stirred Media Mill

Particle Characterisation and Grinding Behaviour of Gamma-Alumina Slurries Prepared in a Stirred Media Mill

Atomically dispersed rhodium on a support: the influence of a metal precursor and a support

Structural Effects of Lanthanide Dopants on Alumina

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