On the mechanism of interaction between TiCl4 vapour and surface OH groups of amorphous SiO2

Thermal Transformations of Titanium Oxochloride Nanostructures on Silica Surface

“…However, comparison of the results of syntheses performed at the same T 0 by different authors shows that the values of n widely vary. In the case of silicas thermally treated at moderate temperatures (180 3 300oC), the Cl/Ti ratio in the products synthesized varied between different studies from 0.5 to 2.6 [6]. Such strong discrepancies may occur for several reasons.…”

“…The functionality of titanium oxochloride surface structures formed in TiCl 4 chemisorption largely depends on the initial concentration of silanol groups, which is determined by the temperature T 0 of preliminary annealing of silica [2]. A review of the available experimental data on the influence exerted by T 0 on the nature of TiCl 4 chemisorption makes it possible to reveal the general pattern consisting in that the Cl/Ti ratio in surface groups increases from 1 to 3 as the concentration of =Si3OH decreases (with increasing T 0 ) [2,6]. However, comparison of the results of syntheses performed at the same T 0 by different authors shows that the values of n widely vary.…”

“…In TiCl 4 chemisorption from a solution of n-heptane or in a vacuum under static conditions, mostly 3OTiCl 3 groups are formed on the surface of dehydrated silica [6]. Carrying out chemisorption under the same temperature conditions in a flow-through system with simultaneous removal of gaseous reaction products (HCl) makes it possible to shift the equilibrium toward a more complete course of the reaction [1].…”

SiO2 thin film growth through a pure atomic layer deposition technique at room temperature

“…Thus, the state-of-the-art production of SiO 2 at RT using a constant ow of NH 3 has been compared to pulse NH 3 -catalysed RT-ALD. Inspired by the reactivity of chlorinated precursors described by Damyanov et al, 49 the amount of contamination could be cautiously explained by the functionality x of the adsorbed species at the surface explained hereaer:…”

Determination of chromium and titanium in silica-based catalysts by ultraviolet/visible spectrophotometry

“…According to Damyanov et a1. 6 and Zyskowski and Skupinski,7 titanium bound to silica in the +4 oxidation state can be released without decomposing the silica. Damyanov et al dissolved titanium/silica samples prepared in the gas phase with TiCI4 in 1 mol dm-3 sulfuric acid before determining the titanium by atomic absorption spectrometry (AAS) .…”