Science News

Extracting Hydrogen from Methanol

Thu, 28th Feb 2013

Laura Howes

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Hydrogen fuel cells, we keep being told, are the future. A clean energy source that has water as its only emission. But we're often told that hydrogen cars are still a few years away, and one of the reasons for that is the problem of hydrogen storage. Hydrogen exists at room temperature and pressure as a gas.

hydrogen tankGases, by their nature, are not very dense and so to hold the amount of hydrogen to fuel a car for a long drive requires squishing the gas down at with a lot of pressure and then carrying a pressurised container in your car. This adds weight, cost, and can make people worry about safety.

Aware if this problem, scientists in Germany and Italy have discovered a way to extract hydrogen gas from methanol at low temperatures and pressures, meaning that instead you could fill your car up with liquid methanol and then convert it to hydrogen as it's needed.

Using methanol to form hydrogen is not new and is a well-known process known as reforming, but until now it has needed high temperatures and pressures, making in less than ideal for use in cars. The approach devised by this group, led by Matthias Beller of the University of Rostock, uses what's called a pincer complex to accelerate the conversion of methanol to formaldehyde then formic acid and finally carbon dioxide, releasing a hydrogen atom with each step. Crucially this happens at temperatures below 100C and without adding any pressure.



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Why not just use the methanol as a fuel?
Bored chemist, Sat, 2nd Mar 2013

Absolutely........................and if I'm not mistaken, methanol has a greater BTU output than pure hydrogen resulting in big gains in horse power. Also, it can use the very high compression ratios without detonation problems associated with pre-ignition. I was involved in the sport of drag racing for many years and know the advantages of methanol for use in the internal combustion engine. Ethos_, Sat, 2nd Mar 2013

In the article, I think they are actually producing carbon dioxide and water from the methanol.
I.E. They are using the methanol as fuel.

However, I think the goal is to make a low temperature fuel cell. 

Hydrogen, methane, and presumably methanol can be used in fuel cells.  However, the high pressure/temperature requirements make them somewhat unfeasible for use in automobiles. 

If a fuel cell can be run at less than 100C, and near 1 ATM, it certainly would be much more practical, assuming, of course, that it is also reasonably efficient.  Warming it up, and cooling it down would not be as problematic either. CliffordK, Sun, 3rd Mar 2013

Because no one liquid has it raw power and it could not be use as it is... shagydeep, Thu, 14th Mar 2013

Clearly it can ~ Using a Direct-methanol Fuel-cell (DMFC).
However, they are inherently inefficient, mainly due to an effect called 'cross-over'.  Also in DMFC the methanol has to be delivered to the cell in the form of a weak solution, making it fairly useless for transportation.  The other option, prior to developing this process, involved reforming the methanol via an independent step then feeding the hydrogen gas produced to a standard PEM cell, but this is both more complex and bulky, and needs to operate at higher temperatures.

This type of cell design has a lot of potential (said as someone who thinks the 'hydrogen economy' is non-starter) because it appears that all the reforming reactions (three in all) are happening at the cell interface.  Although methanol is a fairly low energy-dense fuel (with less than half that of petrol), it has the potential to integrate with our current road-fuel infrastructure with far fewer issues than hydrogen would cause.
peppercorn, Tue, 19th Mar 2013

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