Kinetics of TiCl₄ Hydrolysis in a Moist Atmosphere

Abstract

The gas-phase hydrolysis of TiCl4 has been studied with several laboratory reactors. Unexpectedly, the reaction is clearly split in two steps, an almost instantaneous partial hydrolysis which produces 2 mol of HCl/mol of TiCl4 together with a salt, identified as Ti(OH)2Cl2. The latter forms a very fine dust which easily evolves into aerosols. Ti(OH)2Cl2 in a moist environment eventually hydrolyses to HCl. The kinetics of both steps have been studied. While the first step is very fast, the salt hydrolysis is much slower, its kinetics being controlled by diffusion of the gaseous reactant through the shell of the solid product covering the aerosol particles.

Controlled deposition of titanium oxide overcoats by non-hydrolytic sol gel for improved catalyst selectivity and stability

“…Due to the lower reactivity of self-condensation compared to hydrolytic cleavage, we expected the precursor to react preferentially with the substrate surface. As Ti-Cl bonds are more reactive than Ti-O i Pr toward hydrolysis [46,47], we postulated a surface condensation model where surface hydroxyls reacted primarily with the chloride ligands, leading to the formation of HCl. Each titanium center could react with one or two hydroxyl groups, yielding a mono or bis-grafted species (Fig.…”

Optical visualization of individual ultralong carbon nanotubes by chemical vapour deposition of titanium dioxide nanoparticles

“…TiCl 4 , which is a highly volatile metal halide, was used as the precusor for TiO 2 NPs. TiCl 4 forms misty smog of TiO 2 and HCl upon contact with humid air 45 . When TiCl 4 vapour gets into contact with suspended CNTs, tiny TiO 2 NPs nucleate on the CNTs (Fig.…”

Recovery of TiCl4from the slurry formed in raw titanium tetrachloride by extraction with halogenated hydrocarbon

“…This may be attributed to the fact that the Ti, Al and Nb existed as TiCl 4 , AlCl 3 (or AlOCl) and NbCl 5 (or NbOCl 3 ) respectively in the slurry. And, AlCl 3 , AlOCl, NbCl 5 and NbOCl 3 are all polar molecules which are insoluble in non-polar dichloromethane, while non-polar TiCl 4 is soluble in CH 2 Cl 2 . Therefore, titanium can be separated effectively from the residue by CH 2 Cl 2 .…”

“…3 The slurry contained TiCl 4 has a high recovery value, meanwhile, it is easy to hydrolyze in atmospheric humidity to produce a large amount of heat and HCl, which is a toxic gas. [4][5][6][7] Therefore, many methods were proposed to recover TiCl 4 from the slurry, which includes microwave heating, chloridizing furnace gas heating and spray drying. 3,8 So far, in commercial operations, the only method used to recover TiCl 4 from the slurry is to return the slurry to the chloridizing furnace.…”