Kinetic Analysis of Hydrogen Reduction of Nickel Compounds

Abstract

A review on the hydrogen reduction kinetics of NiO, NiCO3, and Ni(OH)2 hydrogen was conducted, and the most significant experimental values and results were summarized from the past two decades. Isothermal hydrogen reduction experiments of NiO, NiCO3, and, Ni(OH)2 experiments were carried out at 300 °C, 400 °C, and 500 °C, and the obtained data were fitted to multiple different solid-state kinetic models in order to compare the suitability of the models. Non-isothermal reduction in H2 (0 °C→\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ o $$\\end{document} 900 °C) showed the decomposition of NiCO3 at a temperature range of 230 °C to 300 °C and Ni(OH)2 at 220 °C to 300 °C. The calculated Ea values for NiCO3, Ni(OH)2, and NiO varied between 30 and 35, 36 and 37, and 21 and 26 kJ/mol, respectively. Most of the used models were well fitted making the choice of unequivocally the best suitable model difficult and the identification of the mechanism behind the reaction. It was concluded that an increase in temperature accelerates the reduction process, and the reaction rate-controlling mechanism requires more extensive investigation.