Hydrothermal crystallization of boehmite from freshly precipitated aluminium hydroxide

Musić, Svetozar; Dragčević, Đurđica; Popović, Stanko

doi:10.1016/s0167-577x(99)00088-9

Cited by 129 publications

(70 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The sample undergoes visible phase transformations related to the appearance of well crystallized TKl phase and another phase, which is ascribed to boehmite, AlO(OH) (JCPDS file 01-076-1871), originating from gibbsite during the treatment. The transformation of gibbsite to boehmite under HTT has been examined in detail elsewhere [71]. Traces of the boehmite phase are detected also in the PXRD patterns of the 1.5NiAl-HTT sample.…”

Section: Chemical Analysismentioning

confidence: 99%

Ni–Al layered double hydroxides as catalyst precursors for CO2 removal by methanation

Gabrovska

Edreva-Kardjieva

Crışan

et al. 2011

Reac Kinet Mech Cat

View full text Add to dashboard Cite

The effect of nickel content on the structure and activity of co-precipitated Ni-Al layered double hydroxides (LDHs) as catalyst precursors for CO 2 removal by methanation was studied by variation of the Ni 2? /Al 3? molar ratio (Ni 2? /Al 3? = 3.0, 1.5 and 0.5), and of the reduction and reaction temperatures as well as of the space velocities. Powder X-ray diffraction (PXRD), H 2 chemisorption, and temperature programmed reduction (TPR) techniques were applied for physicochemical characterization of the samples. It was specified that the nanoscaled dimensions of the as-synthesized samples also generate nano-metrical metallic nickel particles (PXRD). The existence of readily and hardly reducible Ni 2? -O species in the studied samples (TPR), affects catalytic performance. The studied catalysts hydrogenate CO 2 effectively to residual concentrations of the latter in the range of 0-10 ppm at reaction temperatures from 400 to 220°C and space velocities between 22,000 and 3000 h -1 . The variation of the CO 2 methanation activity with the changes of space velocities depends on the nickel content, and reduction and reaction temperatures. After reduction at 400 and 450°C, a sample of Ni 2? /Al 3? = 3.0 has demonstrated the highest conversion degree at all the reaction temperatures and space velocities, while a catalyst of Ni 2? /Al 3? = 0.5 dominated in the methanation activity after reduction within 530-600°C. The Ni 2? /Al 3? = 1.5

show abstract

Section: Chemical Analysismentioning

confidence: 99%

Ni–Al layered double hydroxides as catalyst precursors for CO2 removal by methanation

Gabrovska

Edreva-Kardjieva

Crışan

et al. 2011

Reac Kinet Mech Cat

View full text Add to dashboard Cite

show abstract

“…3, peaks at 3616 cm -1 are assigned to O-H stretching vibrations of gibbsite [31]. In addition, peaks at 1019 and 795 cm -1 correspond to O-H bending and Al-O vibrations of gibbsite [32], respectively (0 min). During precipitation, the weak peak at 3090 cm -1 assigned to O-H stretching of boehmite is observed at 30 min, and peaks at 3300, 1066, and 744 cm -1 corresponding to O-H stretching, O-H and Al-O bond vibrations of boehmite, respectively, at 40 min are also observed [33].…”

Section: Ftir Spectra and Xrd Patternsmentioning

confidence: 99%

Precipitation of spherical boehmite from concentrated sodium aluminate solution by adding gibbsite as seed

Liu

et al. 2017

Int J Miner Metall Mater

View full text Add to dashboard Cite

Abstract:The precipitation of spherical boehmite was studied by surface energy calculations, measurements of precipitation ratios, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The surface energy calculation results show that the (001) and (112) planes of gibbsite surfaces are remarkably stable because of their low surface energies. In addition, the (010) plane of boehmite grows preferentially during precipitation because of its low surface energy. Thus, we propose a method to precipitate spherical boehmite from a supersaturated sodium aluminate solution by adding gibbsite as seed in a heterogeneous system. In this method, gibbsite acts as the preliminary seed and saturation modifier. The results show that the fine boehmite first nucleates on the (001) and (112) planes of gibbsite and then grows vertically on the (001) and (112) basal planes of gibbsite via self-assembly, thereby forming spherical boehmite. Simultaneously, gibbsite is dissolved into the aluminate solution to maintain the saturation for the precipitation of boehmite. The precipitation ratio fluctuates (forming an M-shaped curve) because of gibbsite dissolution and boehmite precipitation. The mechanism of boehmite precipitation was further discussed on the basis of the differences in surface energy and solubility between gibbsite and boehmite. This study provides an environmentally friendly and economical method to prepare specific boehmite in a heterogeneous system.

show abstract

“…The structure of boehmite consists of Al(O,OH) 6 octahedral layers (2) and its crystallinity is known to be related to the preparation conditions. Boehmite of low crystallinity is called pseudoboehmite but it has been established that its crystal structure is not significantly different (3).…”

Section: Introductionmentioning

confidence: 99%

Relationship between Formation Conditions, Properties, and Crystallite Size of Boehmite

Okada

Nagashima

Kameshima

et al. 2002

Journal of Colloid and Interface Science

119

View full text Add to dashboard Cite

Hydrothermal crystallization of boehmite from freshly precipitated aluminium hydroxide

Cited by 129 publications

References 16 publications

Ni–Al layered double hydroxides as catalyst precursors for CO2 removal by methanation

Ni–Al layered double hydroxides as catalyst precursors for CO2 removal by methanation

Precipitation of spherical boehmite from concentrated sodium aluminate solution by adding gibbsite as seed

Relationship between Formation Conditions, Properties, and Crystallite Size of Boehmite

Contact Info

Product

Resources

About