Types of hydrides

There are basically three types of hydrides ionic, covalent and transitional metal-interstitial hydrides. 

There are many alloy compositions available. The most common are alloy types  

Metal alloy before hydriding (above), and after hydriding (below). 

Each type has its own particular pressure and temperature characteristics which are suitable for different purposes. 

The most common alloy used for hydrogen storage experiments is AB iron/titanium. This combination has the capacity to hold about 1.95% of its weight in hydrogen. Iron/titanium permits charging (adsorption) and de-charging (desorption) hydrogen at ambient temperatures and relatively low pressures. 

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In the case of terminal C=C (1,2 addition units), i.e. when R=R =H and R" (or R111) = polymer chain, two types of hydride migration are possible, namely (i) The Markownikoff s addition which would lead to the formation of B type repeating units and (ii) The anti Markownikoff s addition which would result in the formation of the observed repeating units C. In the case of Markownikoff s type addition the hydride transfer occurs to Ca and results in the formation of branched alkyl-rhodium intermediate complex shown by Structure 2. Whereas when anti Markownikoff s addition occurs, the resulting intermediate alkyl-rhodium complex has linear alkyl ligand as shown by Structure 3. 

A mechano-chemical synthesis in the Mg-Fe-H system was examined as well [2], Two types of hydrides have been observed, non-crystalline (possibly amorphous) and crystalline. By the addition of a catalytic metaF the enthalpy of desorption improves as shown in Figure 8. 

US DOE is investigating two types of hydrides for solid-state hydrogen storage complex metal hydrides and chemical hydrides. DOE s research on complex metal hydrides is focused on increasing the storage capacity of alanates, extending the durability and cycle lifetime, and improving uptake... 

TYPES OF HYDRIDE COMPLEX 19.2.1 With Molecular Hydrogen... 

The discussion of the covalent hydrides given here is somewhat brief in keeping with the intended purpose of this book. Some of the types of hydrides will be discussed in greater detail in chapters dealing with the other elements. The discussion presented here should serve to introduce the breadth, scope, and importance of hydride chemistry. 

Phosphorus forms many types of hydrides (7-9), called phosphanes (Table I). Phosphine (PH3) and diphosphine (H2P—PH2) are the best known. Phosphine is a colorless, toxic gas with a characteristic smell. The higher condensed phosphorus hydrides tend to form chain and ring structures such as cyclopolyphosphine and catenapolyphosphine, respectively. The PH entity has been detected only by spectroscopic analysis, and PH5, P3H, and P18H2 have not been found. 

Type of hydride Metal/ alloy Hydride Structure Wt% hydrogen Peq- F[Pg.320]

A rough attempt to classify the various types of hydrides is shown in Fig. 5-11. In this Section we deal with binary metallic hydrides.49 ... 

What are the three types of hydrides How do they differ ... 

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