偏硼酸钠对硼氢化钠水解制氢性能的影响

Effect of sodium metaborate on the performance of hydrogen generation from the hydrolysis of sodium borohydride solutions

硼氢化钠是一种高比能的储氢材料,其水解理论产氢量达10.8%(质量分数),应用于质子交换膜燃料电池十分理想。着重考察了水解副产物偏硼酸钠溶解度、饱和析晶状态对硼氢化钠水解性能的影响。由于偏硼酸钠溶解度小,在较高浓度硼氢化钠溶液水解的后期会饱和沉淀析出,少量偏硼酸钠沉淀对硼氢化钠水解速度的影响并不大,热分析及X射线粉体衍射结果表明1mol的NaBO2通常能结合2～4mol的水,以Na2B2O4·8H2O和NaBO2·2H2O形式存在。受NaBO2结晶水的限制,硼氢化钠溶液的产氢量一般不超过7.3%。

Sodium borohydride（NaBH4） is a high density hydrogen storage material containing 10.8wt% H2 in theory. Hydrogen generated from the hydrolysis of its solutions is good enough for proton exchange membrane fuel cell. The influence of byproduct, sodium metaborate （NaBO2）, was investigated, Due to its low solubility, NaBO2 was saturated and deposited in the evening of hydrolysis of high concentration NaBH4 solutions. The deposition of NaBO2 had a little influence on the hydrolysis speed of NaBH4 solutions. The results of TG and X-ray diffraction analysis show that 1 mol NaBO2 is usually can combine with 2-4 mol H20 in form of Na2B2O4·8H2Oor NaBO2·2 H2O. As a result, the hydrogen storage capacity of NaBH4 solutions is generally less than 7.3%.