Thursday, August 30, 2007


Life getting in the way of blogging... a tragedy I know!

I thought I would share an update on the research that I'm doing at school which is pertinent to the topic at hand. We're investigating gas storage capabilities of metal-organic frameworks. For those of you who don't have the benefit of a PhD to explain this stuff so you sound smart, these are low density (not a lot of material in a particular space) solids (crystals) which allow other molecules to reside inside of them. Think Fisher Price Construx or a building without walls, just the iron framework.

The organic ligands (or beams) can be almost anything with diametrically opposed (located on the two opposite ends) metal-grabbing groups (like an acid). In our case, they are one benzene ring (very common organic structure) with two carboxylic acids on either end (like citric acid, nothing too scary) and one amino group (a basic functional group found in proteins). The connectors (clusters at the corners) are zinc atoms surrounding one oxygen atom. This is what they look like at an atomic level. Cluster to cluster is about 12 angstroms or 1.2 x 10^(-9)m (1/1000th of the width of a human hair).

I know the perspective is messed up but here is the same thing in color. Keep in mind that these are CUBIC crystals so each ligand (beam) is perpendicular or parallel to all the others.

Grey is carbon, blue is nitrogen (or possibly a nitrogen... there is only one per ring), red is oxygen and green is zinc. Here are the clusters up close:

The theory is this: many kilograms of these crystals are put into a container (not pressurized). When empty, the tank is cooled slightly and hydrogen is pumped in. The crystals take on the hydrogen like a sponge would take on water. No chemical bonds are changed, no structures are affected and nothing crazy has been done. After the tank is full, it can return to room temperature, totally saturated with hydrogen. While the vehicle (or power plant or lawnmower or whatever) is running, the tank is heated gently to create a positive (low) pressure of hydrogen to ensure a constant supply. The tank can be bumped, shot, breeched, even burned and there would be no explosion or additional fire because the hydrogen is locked into this matrix.

If this doesn't blow your mind something is wrong.

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