Preparation And Hydrogen Storage Property Of Zeolites And Mgnesium-Based Composites

Hydrogen is abundant in storage and rich in sources. Hydrogen has high combustion value without any pollution. So hydrogen is regarded as a promising material in energy in the future. While the safe and reliable storage technique is one of the important premises for hydrogen application. Recently, physisorption has attracted more attention in variety of hydrogen storage methods, because the adsorption need lower energy consumption, adsorption-desorption rate is rapid and the adsorbent can be recycled.In this paper the hydrogen storage property of zeolite with high surface area, big pore volume and proper pore channel under low temperature was investigated. The nano Mg-based hydrogen storage material was got by milling and hot-dispersing with porous materials zeolites as support and its properties were improved. The primary contents and results are as follows:1. The hydrogen storage properties of NaA (LAT), NaX/Y(FAU), L(LTL) and several other reported zeolites were investigated, with their structures and appearances confirmed by XRD and SEM. The primary result was: the physical hydrogen storage of zeolite had great relation with its structure. Zeolite which had proper pore channels and big pore volume had great potential in hydrogen storage.2. The hydrogen storage property of as-synthesized Na-LEV, H-OFF, Na-MAZ and Li-ABW was also investigated. The maximum hydrogen storage of zeolite Na-LEV under 1.6MPa is 2.07wt.% at liquefied nitrogen temperature. Under the same conditions, zeolite H-OFF, Na-MAZ and Li-ABW is 1.75wt.%, 1.64wt.% and 1.02wt.%, respectively. The results showed that: the factors influencing hydrogen storage capacity include main pore diameter, pore volume and surface area, with main pore diameter as a priority factor. Even the material possessing large pore volume doesn't make great hydrogen storage capacity, if it has big pore diameter. The materials with main pore diameter closer to the dynamic diameter (0.289nm), micro-volume, and big pore volume have ideal hydrogen storage capacity.3. Because high dispersed and molecularity Mg is positive to reduce its hydrogen storage temperature and pressure, we want to seek an appropriate way to achieve it. Combining the theorty of many oxides and salts can disperse spontaneouely onto the surface of supports to form a monolayer or submonolayer, MgH₂ dispersed property was investigated. The MgH₂/SBA-15, MgH₂/Na-LEV, MgH₂/H-OFF and MgH₂/Na-MAZ compositions were prepared by mechanical milling and thermal diffusion. The hydrogen storage property of them were also tested. The results showed that: Different amounts of MgH₂ can dispersed monolayedly in the carriers. The optimum condition is dispersed for 5 hours at 648K. The maximum loading of MgH₂ in MgH₂/SBA-15 is 9wt. % and Na-LEV, H-OFF and Na-MAZ is 5wt%, 7.5wt.% and 7.5wt.%, respectively. The hydrogen storage test proved that hydrogen storage capacity could be improved by highly dispersing. The dehydrogenating temperature was lower than pure MgH₂. Hydrogen storage capacity had great improvement compared with prepared MgH₂.