Preparation, Characterization And Hydrogen Storage Poperties Of Two Kinds Of Inorganic Hydrogen Storage Materials

Recently, hydrogen storage materials of ammonia borane compound with highgravimetric hydrogen capacity have become the research focus by nano-loadingtechnology. In the meantime, Mg-based transition metal hydrides with18electronicstructure have also attracted much attention because of their uniquestructure. Thisarticle reviews the research progress of high-capacity hydrogen storage materials, themesoporous medium loading of ammonia borane hydrogen storage materials, as wellas Mg-based transition metal hydrides with18electronic structure. On this basis, thepaper expands the research of the loading of AB in mesoporous material MCM-41and A-MCM-41, the preparation of mesoporous NiO and its loading of AB, and thepreparation and characterization of magnesium-based transition metal hydrides. Themain contents include:（1）AB/MCM-41samples were synthesized by an impregnation method intetrahydrofuran （THF） at room temperature. The ratios of AB: MCM-41are fixed at1:2,1:1, and2:1. The as-prepared samples have been characterized by XRD,SAXRD, FTIR, BET, SEM, and TEM. The results show that most AB was loadedinto the MCM-41with short-range ordered and long-range disorderd phase. TheTG/DSC and TPD/MS investigations show that the AB: MCM-41=1:2sampledecreased the dehydrogenation temperature of AB for10°C without NH3releasingbut with borazine.（2）AB: A-MCM-41samples were synthesized by an impregnation method intetrahydrofuran （THF） at room temperature. The ratios of AB: A-MCM-41are fixedat1:2,1:1, and2:1. The as-prepared samples have been characterized by XRD,SAXRD, FTIR, BET, SEM, and TEM. The results show that AB was loaded into theA-MCM-41with short-range ordered and long-range disorderd phase. The TG/DSCand TPD/MS investigations show that the AB: A-MCM-41=1:2sample decreasedthe dehydrogenation temperature of AB for10°C without any borazine or NH3releasing. （3）NiO（1） was synthesized by a hydrothermal method at the conditions andprocesses of distilled water: ethanol=1:1（volume ratio） with ethanol solution75ml,six nickel chloride10mmol, urea100mmol, and sodium dodecyl sulfate0.5g addedto the reactionkettle, stirred the mixture and heated to110°C for15h, then filtered,washed with water and alcohol, drying at80°C for12h, and finally calcined in thefurnace to300°C with a heating rate of1°C/min for3h. The as-prepared blackNiO（1） is nearly spherical particles with the diameter of50-70nm. AB was loadedinto NiO（1） with the AB:NiO（1） ratio of1:1,1:2, and1:4. The as-prepared sampleshave been characterized by XRD, FTIR, SEM, TG/DSC and TPD/MS. The resultsshow that the sample with the ratio of AB:NiO（1）=1:4suppressed the releasing ofborazine and NH3, and decreased the dehydrogenation temperature for3.6°C.（4）NiO（2） was synthesized by a homogeneous precipitation-template methodin the following conditions: the molar ratio of nickel chloride: sodium dodecylsulfate: urea: distilled water is20:40:600:1200, the mixture stirred in water bath for40°C for0.5-1h, placed in an oven for drying at80°C for20h, filtered, washed withwater and alcohol, dried at80°C for12h, and finally calcined in the furnace to300°C with a heating rate of1°C/min for3h. The obtained NiO（2） powder is consistentwith the JCPDS No.65-2091. NiO（2） is flasks which are consisting of sphericalparticles. AB was loaded into NiO（2） with the AB:NiO（2） ratios of1:1,1:2, and1:4.The as-prepared samples have been characterized by XRD, FTIR, SEM, TG/DSCand TPD/MS. The results show that the AB:NiO（2）=1:4sample suppressed thereleasing of borazine and NH3, and decreased the dehydrogenation temperature for10.2°C.（5）NiO（3） was synthesized by a reflux method in the conditions of the molarratio of nickel chloride: hexamethylenetetramine: distilled water is20:200:350000.The mixture was refluxed at140°C for2.5h, filtered, washed with water and alcohol,dried at80°C for20h, and finally calcined in the furnace to300°C with a heatingrate of1°C/min for3h. The obtained NiO（3） powder powder is consistent with theJCPDS No.89-7130. NiO（3） is consisting of flasks. AB was loaded into NiO（3） withthe AB:NiO（3） ratio of1:1,1:2, and1:4. The as-prepared samples have beencharacterized by XRD, FTIR, SEM, TG/DSC and TPD/MS. The results indicate that the sample with the ratio of AB:NiO（3）=1:4suppressed the releasing of borazine andNH3, and decreased the dehydrogenation temperature for3.2°C.（6）Mg-based transition metal hydrides were synthesized by ball-millingmethod. The molar ratio of nano-Fe: micro-MgH₂is1:3. The mixture was milled for55h. The obtained Mg₂FeH₆phase is consistent with the JCPDS No.38-843. Theproduct contains unreacted Fe and MgH₂. Similarly, the molar ratio of nano-Co:micro-MgH₂is2:5. The obtained Mg₂CoH₅phase is consistent with the JCPDS No.78-215. The conversion analysis by HRTEM and FFT shows that the crystal planespacing of Mg₂CoH₅（101） is0.366nm.