Determination of the heat evolved during sodium borohydride hydrolysis catalyzed by Co_3O_4;

摘要

In this work we present a calorimetric study of NaBH_4 hydrolysis in the presence of Co_3O_4. NaBH_4 can be utilized as source of a high purity hydrogen generated by the hydrolysis reaction (BH_4 +4H_2O-> B(OH)_4 + 4H_2) which is easily controlled by catalysts. A modified Setaram Titrys microcalorimeter was used to determine the enthalpy of hydrolysis in a system where water excess is added to pure solid NaBH_4 as well as to solid NaBH_4 mixed with Co_3O_4. Effects of different amounts of water and NaOH (solid and solution) additions on the rate of hydrolysis reaction were also investigated. Heats evolved under different experimental conditions were always about 240 kJ mol~(-1). Lower amount of water resulted in lower reaction rate. The addition of NaOH solution increased the catalytic activity compared to the addition of the same amount of solid NaOH.