Pyrolysis of HNCO vapor

Back, R. A.; Childs, Jerry D.

doi:10.1139/v68-166

Cited by 23 publications

(12 citation statements)

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“…The results of this study, carried out under high pressures to avoid surface effects, corroborate Back and Childs' qualitative observation that COz is indeed a major primary product of the HNCO reaction in this moderate temperature regime [9]. Under these conditions, the reaction is concluded to be dominated by the bimolecular process, (2) HNCO + HNCO -+ CO, + HNCNH, generating the C02 molecule.…”

Section: Isocyanic Acid (Hnco) Is An Early Product Of Rdx [C-(ch2nno2supporting

confidence: 86%

“…On the other hand, the thermal reaction of HNCO has been reported sometime ago by Back and Childs [9] using a static cell in the moderate temperature range between 823 and 973 K at 5-20 torr pressures. Products measured included H2, N2, CO, C02, HCN, and possibly NH3, NH2CH0, and polymeric materials.…”

Section: Isocyanic Acid (Hnco) Is An Early Product Of Rdx [C-(ch2nno2mentioning

confidence: 93%

“…Under these lower-temperature and low-pressure conditions, surface effects and polymer formation were noted to be quite significant [9].…”

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confidence: 90%

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The thermal reaction of HNCO at moderate temperatures

Lin

et al. 1991

Int J of Chemical Kinetics

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The thermal reaction of HNCO has been studied in a static cell at temperatures between 873 and 1220 K and a constant pressure of 800 torr under highly diluted conditions. The reaction was measurable above 1000 K by FTIR spectrometry. The products detected include CO, COZ, HCN, NH3, and the unreacted HNCO. In this moderate temperature regime, the rates of product formation and HNCO decay cannot be accounted for by a previously established hightemperature mechanism, assuming HNCO + NH + CO (1) as the initiation process. Instead, a new bimolecular reaction, 2HNCO -Con + HNCNH (2), has been invoked to interpret the disappearance of HNCO as well as the formation of various products, most importantly COZ.The concentration profiles of all measured species can be quantitatively modeled, throughout the temperature range analyzed, by varying kz using a modified mechanism. The kinetically modeled values of kz can be effectively represented by exp( -21,240 2 1,96O/T) cm3/mol s .

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Section: Isocyanic Acid (Hnco) Is An Early Product Of Rdx [C-(ch2nno2supporting

confidence: 86%

Section: Isocyanic Acid (Hnco) Is An Early Product Of Rdx [C-(ch2nno2mentioning

confidence: 93%

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The thermal reaction of HNCO at moderate temperatures

Lin

et al. 1991

Int J of Chemical Kinetics

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“…With seven atoms or less in the molecule, the unimolecular decompositions (l), (3), and (4) are likely to be in their pressure-dependent regions at 100 torr and 50OOC…”

Section: Discussionmentioning

confidence: 99%

Kinetics and mechanism of the thermal decomposition of methyl isocyanate

Blake

Ijadi-Maghsoodi

1982

Int J of Chemical Kinetics

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The kinetics of gas-phase decomposition of methyl isocyanate have been investigated in the range of 427-548OC. Two decomposition routes are followed; the predominant one is a radical-chain process giving CO, Hz, and HCN as major products, which has an order of 1.5and an Arrhenius equation given by log k(L1/2/mo11/2.s) = (13.12 f 0.06) -(56,450 f 1670) cal/mo1/2.303 R T. The minor route is the bimolecular formation of N,N'-dimethylcarbodiimide and COz, which from the low activation parameters E, = 31.6 kcal, A = 105.30 L1j2/ mo11/2.s, and the reaction order of 1.57 appears to be heterogeneous.

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“…As can be noticed on Figure 11, a slight impact of gas-phase kinetics can be noticed at the higher edge of the temperature range investigated. HNCO spontaneous decomposition kinetics is rather slow in the temperature range investigated [67,68]. Therefore, the thermal decomposition of HNCO should be triggered by an active species produced by ammelide decomposition.…”

Section: Impact Of Gas-phase Chemistrymentioning

confidence: 99%

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

2011

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This work aims to develop a multi-component evaporation model for droplets of urea-watersolution (UWS) and a thermal decomposition model of urea for automotive exhausts using the Selective Catalytic Reduction (SCR) systems. In the multi-component evaporation model, the influence of urea on the UWS evaporation is taken into account using a NRTL activity model. The thermal decomposition model is based on a semi-detailed kinetic scheme accounting not only for the production of ammonia (NH 3 ) and isocyanic acid (HNCO), but also for the formation of heavier solid by-products (biuret, cyanuric acid and ammelide). This kinetics model has been validated against gaseous data as well as solid-phase concentration profiles obtained by Lundstroem et al. (2009) andSchaber et al. (2004). Both models have been implemented in IFP-C3D industrial software in order to simulate UWS droplet evaporation and decomposition as well as the formation of solid by-products. It has been shown that the presence of the urea solute has a small influence on the water evaporation rate, but its effect on the UWS temperature is significant. In addition, the contributions of hydrolysis and thermolysis to urea decomposition have been assessed. Finally, the impacts of the heating rate as well as gas-phase chemistry on urea decomposition pathways have been studied in detail. It has been shown that reducing the heating rate of the UWS causes the extent of the polymerization to decrease because of the higher activation energy.

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Pyrolysis of HNCO vapor

Cited by 23 publications

References 1 publication

The thermal reaction of HNCO at moderate temperatures

The thermal reaction of HNCO at moderate temperatures

Kinetics and mechanism of the thermal decomposition of methyl isocyanate

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

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