hydrides ara, therefore, not suitable for hydrogen storage applications. 

 The solubility of Vvdrogea in aiuainma, galliua, indiea, end thalliua is 

 too low to be of ai«; interest for tfaa application under ooaaideratioa. 



Silicea, Gercanlua, Tin, Lesd, C h roraiun, MolybtJesaa, Tungsten, 

 Manganese, Tej55£5u5j ead Rhenlua. The solubility of hydrogen in 

 silicea, geraanima, tin, lead, chrosaiua, solybdeauc, tungsten, can- 

 ganese, technetium, and rheniua is too low to be of any practical value 

 in hydrogen storage applications. 



Iron, Cobalt, Kickel, Rutheniua, Rhodium, Palladium, Osmitu, Iridiun, 

 and Platinum. The reaction of hydrogen with iron, cobalt, and nickel is 

 eadothermic, and the solubility is too low to be of any practical conse- 

 quence. The solubilities of hydrogen in ruthenium, rhodium, osaium, 

 iridium, and platinum are also too low to be of any use for hydrogen 

 storage applications. Palladium is the only metal in this group which 

 absorbs hydrogen in appreciable quantity. It forms a hydride of the 

 formula PdHg to PcHq^. The palladium-hydrogen system has been very 

 extensively studide by a number of researchers and a number of publi- 

 cations are available for review [19]. Based upon two of these studies 

 [51, 52], one can see that the concentration of hydrogen in palladium at 

 atmospheric pressure is low and decreases with increasing temperature, 

 the atomic ratio varying between 0.0419 at 280°F and 0.0077 at 1,870°F. 

 To obtain higher compositions, the system pressure has to be increased. 

 At 620 F, the atomic ratio of hydrogen to palladium increases from 0.426 

 at 50 atmospheres to 0.691 at 990 atmospheres. Since system pressure in 

 practical applications may be limited to about 50 atmospheres, the 

 atomic ratio of hydrogen to palladium may be limited to only about 0.43. 



Since mixtures of metals, discussed later, absorb far more hydrogen 

 at lower system pressures, are less expensive, and are easily available, 

 palladium does not appear to be attractive for hydrogen storage applica- 

 tions. 



Arsenic, Antimony. Bismuth. Selenium, and Tellurium. Arsenic 

 hydride, antimony hydride, and bismuth hydride are gaseous, and, there- 

 fore, unsuitable for this application. There is no information avail- 

 able oj selenium and tellurium hydrides, presumably because these elements 

 do not form hydrides readily. 



Vanadium, Niobium, and Tantalum. These metals readily absorb 

 hydrogen at atmospheric pressure and room temperature to form stable 

 hydrides of the stoichiometric formula MH, although in most cases these 

 hydrides are hydrogen deficient [9] and [53 through 55]. Reilly and 

 Viswall [30] have been successful In preparing higher hydrides of vana* 

 dium and niobium of approximate composition MH by direct absorption of 

 hydrogen by the metal. All attempts to prepare tantalum hydride beyond 

 the composition TaH have so far been unsuccessful [30], 



18 



