High-Pressure Hydrogen (10MPa)

Yeah, if you are anything like me you've seen all the cool hydrogenations using 100 atm of hydrogen (1atm is about 100kpa, 100 atm = ~10MPa) and thought bugger, as if it were possible to pressurise hydrogen to that level in the home lab.

Fear not, I found an interesting article, in a Japanese article:

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Hydrogen Production from Waste Aluminium at Different Temperatures with LCA

Takehito Hiraki, Masato Takeuchi, Masaaki Hisa & Tomohiro Akiyama
Materials Transactions
Vol.46(5) 2005, pp.1052-1057
http://www.jim.or.jp/journal/e/46/05/1052.html

Abstract

The recycling of waste metallic aluminum with high chemical exergy, which consumes a large quantity of electricity in the refining process, is insufficient. In particular, the so-called dross generated during the remelting process a part of recycling requires expensive treatment, particularly when the metallic concentration is less than 20%, before it can be landfilled. The purpose of this study is to produce hydrogen from waste aluminum sources, such as dross, using an aqueous solution of sodium hydroxide in a beaker and an autoclave. During the study, the effects of temperature of the aqueous solution on the rate of hydrogen generation are to be chiefly examined. The result obtained from an XRD analysis showed that the white product that precipitated during the experiments contained aluminum hydroxide, the rate of hydrogen generation significantly increased with the concentration of sodium hydroxide and temperature of the aqueous solution, and the activation energy was 68.4 kJ mol
1. In the autoclave experiments, hydrogen is released quickly, along with an increase in the inner pressure to a minimum of 1.0 MPa and an increase in the temperature above 473 K. The results suggested a possibility of a new cost effective process of hydrogen production from waste aluminum along with the by prodution of sodium hydroxide. The life cycle assessment (LCA) of the proposed process for producing not only 1 kg of hydrogen but also 26 kg aluminum hydroxide from waste aluminum was carried out to assess the energy requirement and amount of carbon dioxide emissions. Results suggest that the energy requirement of our process is only 2% and the amount of carbon dioxide emissions is 4%, in comparison to a conventional method.

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Now, I'm thinking the addition of a strong solution of NaOH to Al powder in a pressure vessel, with regulation of addition equipped with valve (and relief valve) and we'd have our very own High-Pressure Hydrogen Generator for all those previously inaccessible hydrogenations. It should be possible to control the pressure (after all, with temperature control they kept it to 1.0MPa (or 10atm), so this looks like a useful find.

Keep it mind it is kind of flammable and explosive, but with people making home-made RDX and shit, Hydrogen looks almost tame.



Attachment: Hiraki.etal.Hydrogen.Production.from.Waste.Aluminium.at.Different.Temperatures.with.LCA.pdf (188kB)
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[Edited on 12-5-2013 by aliced25]

Quote: Originally posted by aliced25

Yet it is claimed as being 99.99% pure? Run it through a drying column on the way to the pressure vessel, that would physically block any contaminants except water and absorb the latter.

Quote: Originally posted by solo

"The hydrogen generated this was contains water, NaOH and aluminium hydroxide. This can easily destroy many hydrogenations." .......I've done my share of hydrogenations for ten years, and never had problems with hydrogenations that contained water.....solo