Publication: Effect of nickel catalyst on the formation of TIH2 experiemntal and numerical
Date
2018-08-04
Authors
Aws Sadoon Mohammed Al Janabi
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Abstract
The formation of titanium hydride (TiH2) was studied in the presence of Nickel (Ni) and ammonia chloride (NH4CI) as a catalyst. Calcium hydride (CaH2) and titanium tetrachloride (TiCl4) were used as a reactant in a hydrogen (H2(g)) atmosphere at 1 atm. Three parameters were investigated, temperature (A), Ni catalyst ratio to CaH2 weight (B), and reaction time (C). Temperature parameter was investigated at, 300 °C, 400 °C, and 500 °C. The Ni catalyst percentage was varied between 10%, 30%, and 50% with respect to CaH2 weight. Reaction time was studied at 3, 4, and 5 hours. Design of experiment software was used to design the experiments while HSC software were used to determine thermodynamic calculations for predicting equilibrium composition. A shrinking core model (SCM) was used to predict the degree of dehydriding, XH (%). The synthesised product were characterised by XRD, SEM/EDS, CHNS, and weight gain calculations The phases detected via XRD were TiOCI, Ca(OH)2, CaCl2*(H2O)x, TiO2 (anatase & rutile), NiTiO3, and CaCIOH. The desired phase, TiH2 was assumed to be formed but reacted with Ni and moisture to form NiTiO3. The sample with the parameters of 500 °C, 50% catalyst, 3 hours of reaction time had the highest weight gain, Xw (%). In contrast, the sample with parameters of 300 °C, 50% catalyst, 3 hours of reaction time had lowest Xw (%). CHNS analysis had detected 2.1 wt.% of hydrogen in the highest Xw (%) sample. SEM/EDS showed the presence of TiO2, Ni, and CaCl2. Design expert software
showed temperature was the most effective parameter for both of the responses, Xw
(%) and XH (%).