Recent developments in the preparation of high surface area metal fluorides

Synthesis and characterization of crystalline nanosized MgF2 powder via microemulsion route

“…The synthesized metal fluorides via these techniques have large particle size and low specific surface area (<100 m 2 /g) [13,14]. Recently synthesis of nanosized MgF 2 on the basis of soft chemical methods has been investigated.…”

“…Nandiyanto et al [12] also followed the previous method and could change the shape and the size of particles by varying the molar ratio of MgCl 2 to NH 4 F to obtain either an amorphous nanosized MgF 2 with cubic morphology at a size of 6 nm or a crystalline one at a size of 100-300 nm. Skapin et al [13] synthesized partially crystalline MgF 2 with a medium range surface area of 70 m 2 /g via oxidative decomposition of magnesium nitrate hydrate, Mg(NO 3 ) 2 Á2H 2 O, with F 2 in liquid HF. Despite the fact that the synthesis of MgF 2 via direct precipitation from aqueous solution is more suitable for scaling up, the obtained powder has bigger crystallites.…”

Aluminium(III) fluoride originating from decomposition of hydrazinium fluoroaluminate(III) under oxidative conditions: Syntheses, X-ray photoelectron spectroscopy and some catalytic reactions

“…Based solely on powder X-ray diffraction results, LHF-samples with large surface area can be regarded as amorphous. However, TEM demonstrates that some structural order is present since they consist of an amorphous phase and nanocrystalline phases of a-and b-AlF 3 [6].…”

“…Such a high temperature is not favourable for the preparation of materials with high surface areas and, for this reason, the possibility of decomposing hydrazinium pentafluoroaluminate(III) by strong oxidizers at room temperature has been explored. A short account of this route has recently appeared and the nanoscopic nature of some of the products demonstrated by electron microscopy, particularly TEM [6]. The Lewis acid properties of the AlF 3 materials prepared in the present work have been examined by pyridine adsorption monitored by FTIR spectroscopy [6] and now through X-ray photoelectron spectroscopic (XPS) analysis in order to permit comparisons with analogous data from sol-gel prepared HS-AlF 3 [7,8].…”

“…A short account of this route has recently appeared and the nanoscopic nature of some of the products demonstrated by electron microscopy, particularly TEM [6]. The Lewis acid properties of the AlF 3 materials prepared in the present work have been examined by pyridine adsorption monitored by FTIR spectroscopy [6] and now through X-ray photoelectron spectroscopic (XPS) analysis in order to permit comparisons with analogous data from sol-gel prepared HS-AlF 3 [7,8]. Finally, the behaviour of the materials as possible catalysts in two reactions, isomerisation of 1,1,2-trichlorotrifluoroethane and the room temperature dehydrochlorination of tert-butyl chloride is examined.…”