Source: http://methanolch4o.blogspot.com.au/ |
I mentioned the Sabatier process in a previous post. Researchers at the University of Southern California have been testing a different approach:
Methanol (CH3OH) is a common topic of conversation when discussing how to replace fossil fuels with a new form of energy storage. The molecule is versatile: it can be used as liquid fuel in internal combustion engines, it’s an important starter for making chemical feedstock used to make plastics or other materials, and it can be produced through a simple reaction between carbon dioxide (CO2) and hydrogen (H2). All these advantages lead some experts to propose a methanol economy, in which methanol replaces fossil fuels as the primary transportation fuel or energy storage medium.
The problem is that burning methanol would still release greenhouse gases into the atmosphere (less than other current fossil fuels), unless we could create methanol using the carbon dioxide already in the atmosphere! Then all the carbon dioxide released during methanol combustion in an engine or power plant would not create any net gain of greenhouse gases in the atmosphere.
This idea of a human-made carbon cycle, mimicking how plants use carbon dioxide in photosynthesis, isn’t new. Power plants in Reykjavik, Iceland already use geothermal energy to react carbon dioxide with hydrogen to create methanol and water. But in these cases, the carbon dioxide is not taken directly from the air. Instead, the geothermal plant first captures the CO2, which is then funneled into the methanol production process.
To simplify this method, USC researchers have now developed the first technique to directly react CO2in air to create methanol. The secret lies in two major developments. First, researchers chose a new catalyst, the mysterious key to speeding up the rate of converting reactants to products in so many reactions. In this case, they tested several varieties of ruthenium complexes: molecules with a ruthenium atom at their center, surrounded by ligands made of phosphorous, nitrogen, and hydrogen. Second, the researchers used polyamines to capture CO2 so the catalyst could do its work and foment the reaction to create methanol. Amines are derivatives of ammonia and contain high amounts of nitrogen, which are important sites to attract and absorb carbon dioxide.
With these advantages in place, the researchers injected air into a solution of the polyamine and catalyst (known as ‘bubbling air’). After heating the solution up to about 125-165 degrees Celsius, they ended with a 79% yield of methanol. This percent is the amount of actual yield divided by the theoretical yield predicted by the stoichiometry of the reaction. This high yield should be seen as a success for a first attempt at direct CO2conversion to methanol!
Read more here.
Interestingly, they didn't first need to produce hydrogen by electrolysis, which is the basis of the Sabatier process. It's not clear, but I assume the hydrogen came from the water.
If we wanted to we could move to a 100% renewables energy system with a decade. Existing cars and lorries would be converted to methanol, and electricity would be produced by wind and solar.
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