Control of NO_x formation and transfer in a flowing plasma reactor

The employment of plasma reactors to efficiently produce nitrogen oxide (NO_x) for the fertilizers industry has been studied in recent years. The current research goal is to reduce the energy cost and increase the yield of NO_x by exploiting the non-equilibrium conditions within the plasma.

In situ Raman spectroscopy is employed to yield maps of temperature and species concentrations. These measurements revealed NO molar fractions up to 0.08 at typical temperatures of around 5000 K, while clearly showing absence of vibrational-translational non-equilibrium.

The details of these measurements are interpreted by comparison with results from a quasi-1D plasma chemistry model. The model reproduces the experimentally measured concentrations quantitatively and demonstrates that excited species are insignificant for the NO_x production. This knowledge was used to provide strategies to control and optimize NO output from the reactor beyond the current state of the art.