摘要
The binary phase diagram NaBO2-H2O at ambient pressure, which defines the different phase equilibria that could be formed between borates, end-products of NaBH4 hydrolysis, has been reviewed. Five different solid borates phases have been identified: NaBO2路4H2O (Na[B(OH)4]路2H2O), NaBO2路2H2O (Na[B(OH)4]), NaBO2路2/3H2O (Na3[B3O4(OH)4]), NaBO2路1/3H2O (Na3[B3O5(OH)2]) and NaBO2 (Na3[B3O6]), and their thermal stabilities have been studied. The boundaries of the different Liquid聽+聽Solid equilibria for the temperature range from 鈭?0 to 80聽掳C have been determined, confirming literature data at low temperature (20-50聽掳C). Moreover the following eutectic transformation, Liq.聽鈫捖營ce聽+聽NaBO2路4H2O, occurring at 鈭?聽掳C, has been determined by DSC. The Liquid-Vapour domain has been studied by ebullioscopy. The invariant transformation Liq.聽ng class="boldFont">鈫?/strong>聽Vap. + NaBO2路2/3H2O has been estimated at 131.6聽掳C. This knowledge is paramount in the field of hydrogen storage through NaBH4 hydrolysis, in which borate compounds were obtained as hydrolysis reaction products. As a consequence, the authors propose a comparison with previous NaBO2-H2O binary phase diagrams and its consequence related to hydrogen storage through NaBH4 hydrolysis.