MgH2 with Catalytic Additives

The catalytic additives that have been investigated in MgH2 can be roughly divided into three important groups metals/intermetallics, oxides, and chemical compounds that include hydrides. Their effect on the desorption properties of MgH2 will be discussed in the following sections. We are not going to discuss absorption since, as mentioned before, absorption is usually much easier than desorption. 

Obviously, in practical situations one can hardly imagine a vacuum pump installed onboard of a fuel cell-powered vehicle. Even if so, the membrane of a Proton Exchange Membrane Fuel Cell (PEMFC) will be soon contaminated by the oil vapors released from the pump (dry pumps are possible but this would enormously complicate the entire design). 

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The well-known catalytic additive to MgH2 is Ni. So far, it has been added as a coarse powder with the size range of a few tens of micrometers. A short review of these early experiments is presented in [117], More recently, Hanada et al. [118] investigated the addition of nano-Ni to ball-milled MgH2. Unfortunately, he used continuous desorption under He gas and the material desorbed 6 wt.%H2 at 160°C in 15,000 s. 

Metal oxides seem to be one of the most potent catalytic additives to MgHr A number of authors investigated only the absorption process of MgH2 catalyzed with a specific metal oxide without an insight into the desorption process. Obviously, the absorption... 

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