Metal hydrides development

We are currently involved in a three phase developmental program to extend the process to other hydrogen containing streams. The program involves screening candidate streams to identify poisonous species for the metal hydrides, developing poison resistant processes for each stream, and demonstrating the process(es) on a pilot scale to establish process economics. 

Metal hydrides development touches many fields of research solid-state physics, surface chemistry, thermodynamics, diffusion, metallurgy, gas-solid reactions, and so on. Therefore, it requires a multidisciplinary approach on a team basis as well as for the individual researcher. Fundamental and applied knowledge still needs to be acquired for the full understanding of this class of materials. The intellectual challenge is exciting and, moreover, the developments will serve to make a better world for future generations. 

Hydrogen-storage alloys (18,19) are commercially available from several companies in the United States, Japan, and Europe. A commercial use has been developed in rechargeable nickel—metal hydride batteries which are superior to nickel—cadmium batteries by virtue of improved capacity and elimination of the toxic metal cadmium (see BATTERIES, SECONDARYCELLS-ALKALINe). Other uses are expected to develop in nonpolluting internal combustion engines and fuel cells (qv), heat pumps and refrigerators, and electric utility peak-load shaving. 

A critical issue is the stabiUty of the hydride electrode in the cell environment. A number of hydride formulations have been developed. Table 5 shows hydride materials that are now the focus of attention. Most of these are Misch metal hydrides containing additions of cobalt, aluminum, or manganese. The hydrides are prepared by making melts of the formulations and then grinding to fine powers. The electrodes are prepared by pasting and or pressing the powders into metal screens or felt. The additives are reported to retard the formation of passive oxide films on the hydrides. 

Nickel-Hydrogen, Nickel-Iron, and Nickel-Metal Hydride. First developed for communication satellites in the early 1970s, nickel-hydrogen batteries are durable, require low maintenance, and have a long life expectancy. The major disadvantage is the high initial cost. For these batteries to be a viable option for electric vehicles, mass production techniques will have to be developed to reduce the cost. 

Secondary batteries can be electrically charged, and these batteries can offer savings in costs and resources. Recently, lithium-ion and nickel-metal hydride batteries have been developed, and are used with the other secondary batteries, such as nickel-cadmium, lead-acid, and coin-type lithium secondary batteries. 

The variety of practical batteries has increased during the last 20 years. Applications for traditional and new practical battery systems are increasing, and the market for lithium-ion batteries and nickel-metal hydride batteries has grown remarkably. This chapter deals with consumer-type batteries, which have developed relatively recently. 

War research forced us to explore new synthetic routes and we discovered the alkali metal hydride route to diborane. This solved the synthetic problem. At the same time we discovered sodium borohydride and developed simple synthetic methods for its preparation and manufacture. 

After the initial two reports of Rh- and Co-catalyzed reductive aldol couplings, further studies did not appear in the literature until the late 1990s. Beyond 1998, several stereoselective and enantioselective reductive aldol reactions were developed, which are catalyzed by a remarkably diverse range of metal complexes, including those based upon Pd, Cu, Ir, and In. In this chapter, transition metal-catalyzed aldol, Michael, and Mannich reactions that proceed via transition metal hydride-promoted conjugate reduction are reviewed. 

More recently homogeneous hydrogenation catalysts, such as RhCl(Ph3P)3, have been developed which are soluble in the reaction medium. These are believed to transfer H to an alkene via a metal hydride intermediate they, too, lead to a considerable degree of SYN stereoselectivity in hydrogen addition. 

The reduction of a-hydroxynitriles to yield vicinal amino alcohols is conveniently accomplished with complex metal hydrides for example, lithium aluminum hydride or sodium borohydride [69]. However, it is still worth noting that a two-step chemo-enzymatic synthesis of (R)-2-amino-l-(2-furyl)ethanol for laboratory production was developed followed by successful up-scaling to kilogram scale using NaBH4/CF3COOH as reductant [70],... 

Not included in the present review is the fascinating new chemistry which results from reaction between diazo compounds and low-valent transition-metal complexes bearing easily displaceable two-electron ligands as well as with metal-metal multiple bonds and metal hydrides whereby a variety of novel organometallic molecules could be obtained. This field has been covered, in accord with its rapid development, by successive reviews of Hermann 19 22) and Atbini23). 

Of those types mentioned in Table 1, main attention has been paid to the development of batteries with Zn, Mg and A1 anodes [1-7]. Recently battery air-metal hydride was proposed and investigated [3,8],... 

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