Study On F-treatment Modification Of La_1.8Ca_0.2Mg₁₄Ni₃ Alloy And Hydriding/Dehydriding Reaction Of The Slurry Composed Of La_1.8Ca_0.2Mg₁₄Ni₃ Alloy And Benzene

The influence of hydrogen absorption and desorption properties of fluorination on La1.8Ca0.2Mg14Ni3 alloy is studied. At the same time, the hydriding and dehydriding properity of the slurry system composed of La1.8Ca0.2Mg14Ni3 alloy and benzene has been studied.After fluorination, the activation property and initial hydriding property of La1.8Ca0.2Mg14Ni3 alloy improved greatly under gasous conditions. The 0.15 M NH4F fluorinated alloy can be activated after 1 time of hydriding/dehydriding cycle under 393 K and 4.0 MPa while the untreated one needs 4 times under the same condition. The fluorinated alloy can partially absorb hydrogen 1.92 wt.% in 20 minutes under 300 K and 4.0 MPa while the as-cast alloy can not absorb hydrogen under this condition. After XRD /XPS/SEM study, the La1.8Ca0.2Mg14Ni3 alloy is composed of the phases as La2Mg17, Mg2ni and LaNi2.28, CaMg2, after fluorination, a new phase MgF2 formed, the surface of the fluorinated alloy has formed a net like structure MgF2. After full activation, the fluorinated one can absorb hydrogen quickly under 453 K, and can finish hydrogenation in 3 minutes with a mass of 4.02 wt.%. In contrast, the untreated can finish hydrogenation in 6 minutes with a mass of 4.08 wt.%. It was found that the fluorination has little function on the dehydriding property of the alloy.The hydriding property of the slurry system composed of La1.8Ca0.2Mg14Ni3 alloy and benzene has been studied in detail. The hydrogenation reaction of benzene is a typic zero grade reaction, and the speed of hydrogenating has no relation of the concentration of benzene or cyclohexane. The hydride of the alloy had a excellent function on catalyzation of the hydrogenating reaction of benzene, the activated slurry system can have a good hydrogenating property under 533 K, and can reach a level of 5.74 wt.%, and the transformation rate of benzene is 98.4%. When using fluorinated alloy, the activated slurry system can appear good hydrogenating property under 513 K, and can reach a level of 5.81 wt.% in 3 hours, and the transformation rate of benzene is 99.6%.The dehydrogenating property of the slurry system composed of La1.8Ca0.2Mg14Ni3 alloy and cyclohexane was studied. The concentration of the slurry has envident influence on the transformation rate of cyclohexane, the transformation rate increased along the tempature during the concentration of 20 wt.%~50 wt.%, the concentration rate reach a max. of 3.24% at 50 wt.%, and then ,the rate decreasedalong the tempature. Under the obturation condition, the fluorinated alloy has a better catalyzing property on the dehydrogenating reaction of cyclohexane in compared with that of the untreated one, and the transformation rate of cyclohexane is 4.23% under the reacting condition of 573K/1000r.p.m, which is 3.13 times of the untreated one. When using membrane composed of palladium as dividing device of hydrogen to form a non-balance reaction of the dehydrogenation of cyclohexane, the transformation rate of cyclohexane of the slurry increased quite a little, under the same condition as above, transformation rate of cyclohexane of the slurry with fluorinated alloy is 10.04%, 2.18 times of the ones under obturation condition.