compounds which will store large amounts of hydrogen at useful pressures 

 and which will release this hydrogen with the addition of low to medium 

 quality heat (100° to 60O°F). As is often the <.ase, each of these 

 compounds presents probleas, and some compounds appear to be better 

 suited for particular applications than others. 



Table 2 has been compiled to show most of the intersct««lllc hydrides 

 which were included in the literature surveyed. Others have been 

 studied (59]; but there was either too little information available, or 

 they were of less interest than those shown. Included in this table is 

 the percentage by weight of hydrogen In ea;h of these compounds. Also 

 Included are statements of serious problems that would make a listed 

 compound undesirable. The fcjr single metallic compounds magnesium, 

 vanadium, niobium, and palladium have been Included for comparison. 



A major problem with most transportable hydrogen storage systei s is 

 their weight. A heavy system requires that more energy be used to *ove 

 It than does a light system; thus, a light system is more desirable than 

 a heavy system. The percentage-by-weight figures In Table 2 can be csed 

 to judge the weights of the systems. A low percentage indicates that 

 more of that particular compound will have to be carried to provide the 

 same amount of hydrogen as a compound with a higher perc ige. Table 

 3 includes those compounds which have a 1Z or better hydtogen content. 

 Table 3 provides several vital points of Information on each of these 

 compounds, when available, along with sose .-omparative figures to provide 

 a basis for judging among the compounds. 



The vital information that have previously been published are tbe 

 density, the hydrogen-atom- to- formula ratio, the dissociation er.thalpy, 

 and the plateau pressure and temperature charts. Infonaation still 

 needed for the desip. of a heat exchanger includes the thermal conduc- 

 tivity and the rates ot hydrogen absorption and desorption. From the 

 information available, the hydrogen density for a system with no voids 

 can be derived as is the case with the hydrogen weight fraction and 

 comparative values for the weight and volume of containers capable of 

 holding an amount of hydrogen with a lower heating value equivalent to 

 that of 10 gallons of gasoline. 



The properties of the four single-element hydrides listed in Table 

 2 and of the liquid and compressed hydrogen without tbeir containers are 

 also included in Table 3. 



The cost estimates of each of these compounds are based on small 

 quantities, as given in the 1974-75 Ventron chemicals catalog [66], and 

 compared to bulk prico. estimates obtained from the Molybdenum Corpora- 

 tion of America. The Molybdenum Corporation of America estimates that 

 mischmetal-pentanickel can probably be provided at a cost of about $5 

 per pound which is one-half of its present large-lot cost. The assump- 

 tion that has been made Is that lanthanum pentanickel will also be 

 available at one-half of its present $25.00 per pound large-lot price. 

 By comparing this price to the price that the Ventron Corporation would 

 charge for the constituent materials a factor of 5.96 vas obtained. The 

 prices of the other compounds were found by first calculating the cost 

 of the constituents of 1 pound of the compound and then dividing by the 

 factor 5.96. 



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