The Preparation And Dehydriding Property Of Na-N-B-H And Na-Ca-B-H Composite

As a new, eco-friendly, abundant, high combustion value and recycled energy carrier, hydrogen energy is studied widespreadly. At present, hydrogen storage and transportation technology is the key bottleneck restricting the effective application of hydrogen energy. Because of outstanding advantages including higher theoretical hydrogen storage capacity and more excellent hydrogen storage property, alkali metal complex hydride hydrogen storage systems attract a lot of research scholars and become research hotspots in the hydrogen storage field at home and abroad in recent years.Based on the review of research status and progress on alkali metal complex hydride hydrogen storage systems, Na-N-B-H composite doping Co-Ni-B catalyst synthesized via liquid phase ball milling is selected as the study object of this work. The Na-N-B-H hydrogen storage material doped with Co-Ni-B catalyst is synthesized via machnically milling the mixture of NaNH2:NaBH4(2:1) in cyclohexane agent. The performance of the composite is analysized and characterized by means of TG-DTA, XRD, FT-IR test and activation energy calculation. We discuss the catalytic effects on hydrogen storage properties of the composite with different proportion of added catalyst by evaluation indicators of decomposition temperature, activation energy and hydrogen desorption capacity. Moreover, the hydrogen storage property of Na-Ca-B-H composite via machnically milling the mixture of NaBH4 and CaCl2 in cyclohexane agent is also investigated.The experimental results indicate that total weight loss of the composite is 5.05wt% while the temperature reaches 490℃ after addition of 5wt% Co-Ni-B catalyst, which is the most close to the theoretical value. And it mainly generates Na3(NH2)2BH4 composite. Therefore we determine the optimal proportion of added catalyst is 5wt% Co-Ni-B. By comparing the composite with 5wt% Co-Ni-B catalyst and none catalyst, total weight loss of the former is lower than the theoretical hydrogen storage capacity, which indicate that Co-Ni-B catalyst inhibit the generation of impurity gas NH3 to some extent, in addition, the initial dehydriding temperature 80℃, the maximum dehydriding rate temperature 282.9℃ and the decomposition reaction activation energy 69.1KJ?mol-1 of the former are all less than the latter, namely, the hydrogen storage property of the former is superior to the latter. These show that the added catalyst improves hydrogen storage property effectively. And the research shows that the mechanism of decomposition reaction of the composite is three-dimensional, machanism function is f???= ?????]1)1/(1[)1(2/313/13/4 ?.Na-Ca-B-H hydrogen storage material is synthesized by NaBH4 and CaCl2 at various ratio(NaBH4:CaCl2=2:1, 4:1, 6:1) via liquid phase ball milling. And the hydrogen storage performances of the above composites are analysized by means of TG-DTA, XRD and activation energy calculation. Our research show that NaBH4:CaCl2(4:1) is the best reaction ratio, the initial dehydriding temperature was 145℃, the maximum dehydriding rate is at 435.9℃ and the decomposition reaction activation energy is 121.8KJ?mol-1. The total weight loss of the composite is 2.87wt% when the temperature comes to 480℃, and the mechanism of decomposition reaction of the composite is assumed random nucleation and its subsequent growth, machanism function is f???= ??? ??)]1ln()[1(4/1 ?3.