Sciencemadness Discussion Board

High surface area materials for blending mixtures of energetic materials

DDTea - 16-12-2010 at 09:12

This is a half-baked idea so I'm throwing it here in "beginnings." Also, my knowledge of energetic materials and compositions is next to nil, so please correct me where appropriate.

There was a member on roguesci some years ago who was interested in ammonium nitrate/nitromethane (ANNM) compositions. He found through his calculations that when properly balanced, the ammonium nitrate ought to be swimming in nitromethane to form a sort of slurry. His idea was to dissolve the ammonium nitrate into water, then adsorb the resulting solution onto cotton balls. These cotton balls were subsequently dried in an oven to drive off the water. The cotton balls were then used to adsorb nitromethane.

Cotton balls seem very crude and I imagine the mass of cotton would affect the oxygen balance in a detrimental way, or at least would be a nuisance to make calculations for.

I work with high surface area materials such as zeolite catalysts and I'm always interested in finding new, unconventional ways of using them. Something with a surface area 800+ m^2/g is excellent for deodorizing a stinky office fridge! I suspect it may also be good for the application just described: as an adsorbant material in energetic compositions that might aid in even blending of the composition. However, depending on the specific chemical to be adsorbed, there may be issues with pore sizes. Overall, though, this seems like a better and more predictable adsorbant than cotton balls. Zeolites, for example, are largely silicon dioxide and aluminum oxides, which already being bound to oxygen, should not affect the oxygen balance of the composition (is my logic correct?). If this is sound logic, it might have applications beyond sensitized ammonium nitrate compositions to other liquid energetic materials (nitroglycerin, for example).

[Edited on 12-16-10 by DDTea]

ScienceSquirrel - 16-12-2010 at 09:20

1) This should be in energetic materials

2) Keiselguhr, a diatomaceous earth, is used to absorb and desensitise nitroglycerine. I imagine that hundreds of other things have also been tried.

DDTea - 16-12-2010 at 09:33

Hah, silly me, hypothesizing about reinventing dynamite... doh!

The main advantage to using some super high surface area silica or zeolite for this purpose, though, is that it could significantly reduce weight over using diatomaceous earth. For engineering purposes, this may not be an important consideration, especially when cost is factored in. Maybe sponge-metal catalysts would be good here (e.g. Raney nickel)? With the right calculations, I'm sure you could both fully adsorb liquid materials into the matrix and also achieve a proper oxygen balance by incorporating the said metal.

DDTea - 17-12-2010 at 20:49

Thinking about this idea a bit more, another good application for high surface area materials would be for adsorbing energetic materials that are normally in the gas phase at room temperature. I can't think of anything in particular, but it's an idea.

crazedguy - 21-12-2010 at 15:36

By absorbing a gas do you mean turning it into a liquid because that would be the only way to make an explosive gas more stable as far as I know.

DDTea - 23-12-2010 at 17:13

What I meant was literally adsorbing the explosive, in the gas phase, into the pores of some high-surface area material (e.g., a zeolite or silica gel). I don't know how well the explosive gas would stay in place (I know that N2 will slowly leak out over time). I also have no clue whether it would be stabilized or destabilized by being adsorbed. The idea was simply to make handling explosive gasses more convenient.

I'm just brainstorming, basically.