Power‐Law Kinetic Models for Synthesis of Ammonia Borane

• Published in: International journal of chemical kinetics 2017-12, Vol.49 (12), p.875-883
• Main Authors: Ozgur, Derya Öncel, Ozkan, Göksel
• Format: Article
• Language: English
• Subjects: Ammonia; Chemical synthesis; Dehydrogenation; Hydrogen; Hydrogen storage materials; Hydrogen-based energy; Kinetics; Reaction kinetics
• ISSN: 0538-8066; 1097-4601
• DOI: 10.1002/kin.21134

ABSTRACT In the past few years, there have been increasing numbers of studies for the production and dehydrogenation of ammonia borane (NH3BH3, AB), which has become a significant hydrogen storage material. However, kinetic model studies based on the synthesis of AB in the literature have not been encountered, though there are many kinetic modeling studies on dehydrogenation of AB (Akbayrak et al., Appl Catal B 2016, 198, 162–170; Choi et al., Phys Chem Chem Phys 2014, 16(17), 7959–7968; Esteruelas et al., Inorg Chem 2016, 55(14), 7176–7181; Park et al., Int J Hydrogen Energy 2015, 40(46), 16316–16322; Rakap, Appl Catal B 2015, 163, 129–134; Tonbul et al., Int J Hydrogen Energy 2016, 41(26), 11154–11162; Zhang et al., Int J Hydrogen Energy 2016, 41(39), 17208–17215). The paper describes the development of a kinetic model for synthesis of ammonia borane by using borohydride (NaBH4) and ammonium salt (NH4)2SO4. The synthesis of AB experiments was carried out at different temperature ranges between 25 and 50°C, different inlet molar ratios (NaBH4/(NH4)2SO4 = 1–4), and different molarities with respect to NaBH4 (0.11–0.67 M NaBH4). After the parametric experiments were conducted, empirical power law was evaluated for the synthesis reaction. The power‐law model represented the trends of the kinetics of the synthesis reaction and was reproduced as r apparent =koexp(−EaRT)[C NaBH 4]0.7[C( NH 4)2 SO 4]0.3(ko=2.02×106h−1,Ea=37.8 kJ mol −1).