New Insight For Cheaper Ammonia as NH3

A couple of barriers sit in the way of the ammonia NH3 folks looking for lower costs and a chance at the fuel business.
The N part or nitrogen is great stuff, it makes up about 80% of the atmosphere and its highly non-reactive and stabile tendency is a very good thing.  If oxygen and nitrogen were reversed in atmospheric proportion the oxidation rates and combustion potential would make life as we know it impractical.  It a very good thing there is so much around.  But for making things like NH3 that stability and non-reactive nature is a problem.
Then the 100+ year old Haber-Bosch Process (HBP) is a hot and high pressure process.  It takes a lot of energy and usually uses an energy source like natural gas to get the hydrogen for building the molecules.  How HBP works, though, hasn’t been explained so far.
But HBP works and works well, reliably and it’s a well-entrenched technology with a vast industrial base.  It’s not going to change without powerful incentives.
How HBP works at the catalysts surface has been something of a mystery until now. Scientists have had little understanding of how it actually works.  Now a team of chemists, led by Patrick Holland of the University of Rochester, has new insight into how the ammonia is formed. Their findings have been published in the latest issue of Science.
Holland calls nitrogen molecules “challenging.” They’re abundant so they’re desirable for research and manufacturing, but their strong triple bonds are difficult to break, making them highly unreactive. For the last century, HBP has made use of an iron catalyst at extremely high pressures and high temperatures to break those bonds and produce ammonia, one drop at a time.
Holland said, “The Haber-Bosch process is efficient, but it is hard to understand because the reaction occurs only on a solid catalyst, which is difficult to study directly. That’s why we attempted to break the nitrogen using soluble forms of iron.”
Holland’s team, which includes Meghan Rodriguez and William Brennessel at the University of Rochester and Eckhard Bill of the Max Planck Institute for Bioinorganic Chemistry in Germany have succeeded in mimicking the process in solution.
They discovered that an iron complex combined with potassium was capable of breaking the strong bonds between the nitrogen atoms and forming a complex with an Fe3N2 core, which indicates that three iron (Fe) atoms work together in order to break the N-N bonds. The new complex then reacts with hydrogen (H2) and acid to form ammonia (NH3) – something that had never been done before by iron in solution.
Using the atmosphere’s N2 molecule cracked apart makes the NH3 build possible.  Knowing the crack needs three iron atoms working together is going to have implications for process designers.   Anything to cut costs such as lower operating pressures and or temperatures is going to help.
Holland makes clear that his new process isn’t going to be directly applicable because the team’s catalyst is much more expensive.  But Holland says it is possible that his team’s research could eventually help in coming up with a better catalyst for the HBP – one that would allow ammonia to be produced at lower temperatures and pressures.
Like lots of other research another point came up.  When the team’s iron-potassium complex breaks apart the nitrogen molecules, negatively charged nitrogen ions – called nitrides are formed. Holland says the nitrides formed in solution could be useful in making pharmaceuticals and other products.
Now the work needs done of confirming the iron potassium catalyst truly matches the strictly iron activity.  If that works, like it should, then new catalyst designs would become worthy ideas. That’s when the opportunities for lower energy inputs needed for the temperature and pressures might appear.
This is good basic research.  Now, subject to confirmation, the activity of making the N2 into to a simple N can be visualized.  Keep in mind the new catalyst also does the re combine with the hydrogen as well.
Catalyst research on a hundred year old success is getting NH3 a bit closer to getting some more market traction.