Kinetics of the NH reaction with H2 and reassessment of HNO formation from NH + CO2, H2O

Abstract

The reaction of ground state NH with H2 has been studied in a high-temperature photochemistry (HTP) reactor. The NH (X 3 Σ) radicals were generated by the 2-photon 193 nm photolysis of NH3, following the decay of the originally produced NH(A 3 Π) radicals. Laserinduced fluorescence on the NH(A 3 Π-X 3 Σ 0,0) transition at 336 nm was used to monitor the progress of the reaction. We obtained k (833-1432 K) = 3. showing the barriers leading to these products to be too high compared to the measured activation energies. The calculations indicate the likelihood of formation of adducts, of low stability. These then may undergo further reactions. The NH + H2O reaction is briefly discussed and it is similarly argued that HNO + H2 cannot be the products, as had been previously suggested.3

Ammonia chemistry in oxy-fuel combustion of methane

“…However, the products of the NH þ CO 2 reaction are in question. Even though HNO + CO appear to be the most likely products, it has been pointed out [31,32] that reaction (78) is too endothermic to be consistent with the observed high temperature rate constant for NH þ CO 2 . Furthermore, flow reactor and jet-stirred reactor experiments [28,33] indicate that formation of NH by the reverse reaction of HNO with CO (78b) is insignificant.…”

“…Furthermore, flow reactor and jet-stirred reactor experiments [28,33] indicate that formation of NH by the reverse reaction of HNO with CO (78b) is insignificant. It has not been possible through theoretical work [31,32] to identify a set of products for NH þ CO 2 that is consistent with the rate measurements and further work on this reaction is required.…”

Formation and consumption of NO in H2+O2+N2 flames doped with NO or NH3 at atmospheric pressure

“…Further quantum chemical and experimental studies [42,43] strongly supported the measurements of Rohrig and Wagner [39] for direct reactions between NH and H 2 , H 2 O, and CO 2 rejecting, however, HNO and H 2 as the products of reaction (8).…”

Modeling nitrogen chemistry in combustion

“…Competing consumption steps of NH 2 include reactions with the O/H radical pool (R57-R61), with amine radicals leading to formation of N 2 -amines, and, at high excess oxygen levels, with O 2 (R62, R63). The NH 2 + H reaction (R57b) has been measured both in the forward [230,231] and reverse [199,232] Oxidation of ammonia has been studied extensively in the past, both experimentally and through modeling. The experimental work include studies in ames [238245], shock tubes [185,246253] and ow reactors [136,140,237,254,255].…”