Hydrolysis of ZrCl4 and HfCl4: The Initial Steps in the High-Temperature Oxidation of Metal Chlorides to Produce ZrO2 and HfO2

Journal Article · Fri Mar 08 04:00:00 EST 2013 · Journal of Physical Chemistry C, 117(15):7459-7474

DOI:https://doi.org/10.1021/jp400228d· OSTI ID:1097917

Fang, Zongtang; Dixon, David A.

The gas-phase hydrolysis of MCl4 (M = Zr, Hf) to produce the initial particles on the way to zirconia and hafnia nanoparticles has been studied with electronic structure theory. The potential energy surfaces, the themochemistry of the reaction species, and the reaction paths for the initial steps of MCl4 reacting with H2O have been calculated. The hydrolysis of MCl4 at higher temperatures begins with the formation of oxychlorohydroxides followed by the elimination of HCl instead of the direct production of MOCl2 and HCl or MO2 and HCl due to the substantial endothermicities associated with the formation of gas-phase MO2. The structural properties and heats of formation of the reactants and products are consistent with the available experimental results. A number of metal oxychlorides (oxychlorohydroxides) intermediate clusters have been studied to assess their role in the production of MO2 nanoparticles. The calculated clustering reaction energies of those intermediates are highly exothermic, so they could be readily formed in the hydrolysis process. These intermediate clusters can be formed exothermically from metal oxychlorohydroxides by the elimination of one HCl or H2O molecule. Our calculations show that the mechanisms leading to the formation of MO2 nanoparticles are complicated and are accompanied by the potential production of a wide range of intermediates, as found for the production of TiO2 particles from the high-temperature oxidation of TiCl4.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1097917
• Journal Information: Journal of Physical Chemistry C, 117(15):7459-7474, Journal Name: Journal of Physical Chemistry C, 117(15):7459-7474
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory