NH3BH3 AND NaBH4 ENCLOSED IN GEOPOLYMERS AND ZEOLITES

Aminonia-borane, NH3BH3 ( = AB) and sodium tetrahydroborate (NaBH4 = SB) can easily be dissolved in sodium aluminate and silicate solutions. Upon mixing they result in immediate gel formation and re-crystallization of AB and SB during drying. In case of AB-GIR-absorption spectra indicate that the geopolymer matrix (= G) consists of mainly sialate units (Si-O-Al-O). Heating experiments to 120, 150 and 300 degrees C show the formation of polyaminoboranes (PAB) and polyiminoborane (PIB). The underlying reactions could he related to hydrogen release in two exothermic peaks observed at around 122 degrees C and 160 degrees C. In the course of further optimizations of the SB content in SB-G the Si/Al ratio of G could slightly increase with increasing the Si/Al ratio between 0.27 and 2.7. The water content of SB-G decreases linearly with the decreasing contribution of the geopolymer matrix. SB-SOD could be crystallized systematically following a hydrothermal soft chemical synthesis technique at 60 degrees C, 80 degrees C and 120 degrees C. The effect of variations in particle and crystallite sizes could be correlated with effective hydrogen release and the water content in the matrix of the SB-SOD.