Thermoanalytical and NMR investigation of NaBH4 × 2H2O thermolysis process

• Published in: Journal of thermal analysis and calorimetry 2018, Vol.132 (1), p.155-163
• Main Authors: Arkhangelskii, I. V., Tarasov, V. P., Kravchenko, O. V., Kirakosyan, G., Tsvetkov, M. V., Solovev, M. V., Dobrovolskii, Yu. A., Shihovzev, A. V.
• Format: Article
• Language: English
• Subjects: Acetonitrile; Analytical Chemistry; Catalysis; Catalysts; Chemistry; Chemistry and Materials Science; Enthalpy; Exothermic reactions; Inorganic Chemistry; Measurement Science and Instrumentation; NMR; Nuclear magnetic resonance; Oxidation; Physical Chemistry; Polymer Sciences; Reaction kinetics; Sodium; Solids
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-017-6953-5

The article describes the thermolysis process of sodium borohydride dihydrate in thermoanalytical experiments. The reaction was carried out without solid catalyst and with catalyst as cobalt boride Co 2 B. It has been found out that in both cases the process starts after the peritectic reaction of the starting compound and forms a liquid phase. The enthalpy of peritectic reaction is Δ H react  = 19 ± 2 kJ mol −1 . When thermolysis proceeds in acetonitrile solution without a catalyst, intermediate hydroxyborohydride NaBH 3 OH or/and Na(BH 3 ) 2 OH is formed according to the NMR experiment data. The formation of similar complexes in the solid phase is confirmed by experiments on the oxidation of the thermolysis products. Thermolysis process with solid catalyst proceeds with an intense exothermic effect at more lower temperatures. The kinetics of the non-catalytic process is described by the model of two consecutive reactions, and reaction with the solid catalyst model is approximated by two parallel reactions.