Hydrogen adsorption and absorption

A number of metals have the ability to absorb hydrogen, which may be taken into solid solution or form a metallic hydride, and this absorption can provide an alternative reaction path to the desorption of H,. as gas. In the case of iron and iron alloys, both hydrogen adsorption and absorption occur simultaneously, and the latter thus gives rise to another equilibrium involving the transfer of H,<,s across the interface to form interstitial H atoms just beneath the surface ... 

A. Zolfaghari and G. Jerkiewicz, in Electrochemical Surface Science of Hydrogen Adsorption and Absorption (eds. G. Jerkiewicz, P. Marcus),... 

During the last two decades, hydrogen adsorption and absorption were shown to play a central role in a whole series of papers by Czerwinski and coworkers [120-133]. 

The particular importance of surface effects in hydrogen adsorption and absorption by metals, for getters, permanent magnets, in catalytic reactions, battery electrode reaction, H embrittlement and plasma-waU interaction in fusion stems from two facts The first relates to the surface itself The sharp discontinuity of matter with electric charges and potentials of electrons and atom cores at the surface together with the loss of periodicity in the direction orthogonal to the surface leads to... 

Jerkiewicz, G. (2010) Electrochemical hydrogen adsorption and absorption. Part 1 underpotential deposition of hydrogen. 7ecfrocafa/y5W, 1, 179-199. 

Based on Figure 4.35, the major role of Pt was to stabilize Pd at the expense, unfortunately, of the catalytic activity. The best performance was obtained with a 1 1 Pd Pt atomic ratio [174], The long-term poisoning mechanism of Pd has not been discussed. The elucidation of the role of hydrogen adsorption and absorption into the bulk Pd electrode, in conjunction with COad and/or oxidation of the Pd surface, could represent venues to be explored in order to shed light on the deactivation mechanism. 

Conversion Processes. Most of the adsorption and absorption processes remove hydrogen sulfide from sour gas streams thus producing both a sweetened product stream and an enriched hydrogen sulfide stream. In addition to the hydrogen sulfide, this latter stream can contain other co-absorbed species, potentially including carbon dioxide, hydrocarbons, and other sulfur compounds. Conversion processes treat the hydrogen sulfide stream to recover the sulfur as a salable product. 

Tateishi N, Yahikozawa K, Nishimura K, Masato S, Iwanaga Y, Watanahe M, Enami E, Matsuda Y, Takasu Y. 1991. Electrochemical properties of ultra-fine palladium particles for adsorption and absorption of hydrogen in an aqueous HCIO4 solution. Electrochim Acta 36 1235-1240. 

Jafarian et al. [130] have studied adsorption and absorption of hydrogen species on Ag electrodes in alkaline solution. Gurten etal. [131] have investigated the effect of alcohols MeOH, EtOH, and PrOH on hydrogen evolution reaction on Ag electrode in contact with 0.01 M NaCl solution. It was observed that the presence of alcohols increased the hydrogen yield and decreased anodic overpotential (for the Pt anode). 

The term adsorption was first used by H. Kayser in 1881. J. W. McBain introduced a similar term in 1909, i.e. absorption , to determine an uptake of hydrogen by carbon much slower than adsorption. He proposed the term sorption for adsorption and absorption (Dabrowski, 2001). 

Hydrogen-induced plasticity. Another approach is related to the fact that hydrogen increases local plasticity. Two models have been proposed based on the adsorption and absorption of hydrogen. 

The influence of temperature on the occlusion by palladium has also been investigated by Firth.6 He employs the term adsorption to denote the surface phenomenon of rapid occlusion of hydrogen, diffusion not being a determinable factor limits absorption to slow occlusion in which the rate of diffusion or solution is a determinable factor and uses the collective term sorption to include both adsorption and absorption.7 Firth observed adsorption only below 0° C., between 0° and 150° C. he also observed absorption but above 150° C. found absorption only. 

Burch, R. (1979) The Adsorption and Absorption of Hydrogen by Metals, in Chemical Physics of Solids and Their Surfaces, vol. 9, Chemical Society, London,... 

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