Effect of oxygen and additives on thermal decomposition of aqueous urea solution

Progress and Prospective of Nitrogen-Based Alternative Fuels

“…Glarborg et al developed an updated mechanism, suggesting a new pathway in which HNCO reacts with O 2 to form HNO . In a series of works by Rota et al, this channel was suggested to be the main reaction pathway at low temperatures for HNCO-NO systems. − Hydrolysis of HNCO was suggested to be a RDS by Zanoelo, but later modeling efforts for urea systems did not address this result. , Finally, aqueous solutions of ammonia/urea and ammonium nitrate (AAN/UAN) were studied as synthetic monofuels. Attempts at modeling the chemistry of these fuels provided several useful conclusions with relevance for other nitrogen-based systems.…”

“…287−289 Hydrolysis of HNCO was suggested to be a RDS by Zanoelo, 290 but later modeling efforts for urea systems did not address this result. 267,291 Finally, aqueous solutions of ammonia/urea and ammonium nitrate (AAN/UAN) were studied as synthetic monofuels. Attempts at modeling the chemistry of these fuels provided several useful conclusions with relevance for other nitrogenbased systems.…”

A Review of Urea Pyrolysis to Produce NH3 Used for NOx Removal

“…In this paper, Bernhard et al first clearly analyzed and obtained the adsorption form of urea on the surface of TiO 2 and calculated the energy value consumed during the adsorption process. e effect of oxygen concentration and different additives (Na 2 CO 3 and NaNO 3 ) on NH 3 yields and N 2 O and CO production from pyrolysis of aqueous urea solution was studied by our group [22]. Without additives, the presence of oxygen made the NH 3 yields drop rapidly in 550-800°C.…”

“…HNCO + H 2 O ⟶ NH 3 + CO 2 (4) Unfortunately, in the actual urea-based NO x removal process, 1 mole of urea can hardly generate 2 moles of NH 3 . It is mainly due to the following two factors: (i) unignored side reactions in parallel with reactions (3) and (4) and (ii) the rather low reaction rate of (4) [21,22]. ese side reactions include the generation of macromolecular byproducts such as biuret and cyanuric acid, which leads to reduction of NH 3 production.…”