No abstract

By directly introducing Ni-B into NaAlH 4 system using a facile two-step synthesis method, the effects of Ni-B on NaAlH 4 were systematically investigated. NaAlH 4 can be completely formed after 30 h milling under 1 MPa hydrogen pressure. In addition, the dehydrogenation kinetics of as-prepared NaAlH 4 after different milling times were investigated. As the dehydrogenation temperature rises, both the hydrogen desorption capacity and dehydrogenation rate quickly increase. The apparent activation energy E a for Ni-B-doped NaAlH 4 is calculated to be 61.91 kJÁmol -1 for the first dehydrogenation step. More importantly, the dehydrogenation temperature of as-prepared NaAlH 4 nanocrystalline can be reduced to about 100°C.

摘要：采用化学还原法以乙醇为溶剂在冰水浴中合成了一系列 Co 1-x Ni x B 合金催化剂, 研究了该系列合金不同 Ni 含量对 NaBH 4 水解放氢性能的影响.X射线衍射(XRD), 扫描电镜(SEM)和透射电镜(TEM)显示 Co 1-x Ni x B 合 金是纳米非晶态颗粒. 放氢测试表明 Co 1-x Ni x B 具有很高的催化活性. 放氢速率先随着 Ni 含量的增加而增大, 并 在 x=0.15 时放氢速率达到最大值, 然后随 x 值的增加而减小.298K时Co 0.85 Ni 0.15 B 合金催化碱性硼氢化钠水解 的最大放氢速率可达 4228mL•min-1 •g-1 ,CoB 和 Co 0.85 Ni 0.15 B 合金催化放氢的活化能分别为 34.25 和 31.87kJ• mol-1. 因此以乙醇为溶剂合成的 Co 1-x Ni x B 合金具有较高的催化活性.