Cooxidation of ammonia and ethanol in supercritical water, part 1: Experimental results



The cooxidative effect of ethanol on ammonia oxidation in supercritical water was studied for a range of temperatures (655–705°C), initial ammonia (1–3 mM), ethanol (0–1.0 mM), and oxygen concentrations (0.7–5.0 mM), corresponding to fuel equivalence ratios ranging from 0.9 to 2.2 for the complete combustion of both organic species. With a stoichiometric amount of oxygen available for complete oxidation, the addition of ethanol on an equivalent molar basis was found to increase ammonia conversion from 20 to 65% at initial concentrations of 1 mM for each reactant, T = 700°C, P = 246 bar, and τ = 2.5 s. Nitrous oxide was produced in much larger quantities for ammonia–ethanol cooxidation than for ammonia oxidation. Based on fractional yields of nitrogen product, this amounted to 40–75% for co-oxidation with ethanol versus 4–13% without ethanol present. © 2007 American Institute of Chemical Engineers AIChE J, 2007