The reactions of FeO with O3, H2, H2O, O2 and CO2

Rollason, R. J.; Plane, J. M. C.

doi:10.1039/b000877j

Cited by 76 publications

(90 citation statements)

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“…The reverse reaction, FeO + H 2 , is found to have a barrier of 12-13 kcal/mol, which can explain the fact that no reaction was observed between FeO and molecular hydrogen at 320 K in the recent experimental study by Rollason and Plane. 4 The Fe + H 2 O f FeO + H 2 reaction in triplet electronic state has a mechanism similar to that of the quintet reaction. However, significant differences can be seen in the reaction energetics.…”

Section: Resultsmentioning

confidence: 99%

“…3 Among others, FeO may undergo a reaction with molecular hydrogen, which is the reverse of Fe + H 2 O. This reaction was recently studied experimentally 4 and was found to be very slow at 320 K. While the simple and fundamental reaction Fe + O 2 has been examined in argon matrices, [5][6][7][8] in the gas phase, 4,[9][10][11][12] and by theoretical calculations, 8,[11][12][13][14][15] the reactions in the Fe/H 2 O/O 2 system are still far from being understood. Ground-state iron atoms are not reactive with O 2 in the gas phase near room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Study of the Reaction Mechanism of Fe Atoms with H₂O, H₂S, O₂ and H⁺

Mebel

Hwang

2001

J. Phys. Chem. A

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Density functional B3LYP/6-31G**, B3LYP/6-311G**, B3LYP/6-311+G(3df,2p), and ab initio CCSD(T)/ 6-311G** calculations showed the reaction of free iron atoms with water in the ground quintet electronic state to proceed by the formation of a weakly bound Fe-OH 2 molecular complex. The complex is slightly unbound at the CCSD(T)/6-311G** level but stable according to density functional calculations and can isomerize to the HFeOH molecule, overcoming a barrier of 15-33 kcal/mol (with respect to the reactants), but further decomposition of HFeOH to FeO and H 2 is hindered by a high barrier. In the presence of protons (in acidic environment), iron atoms can easily attach H + with formation of the quintet FeH + molecules. The reaction of these molecules with water, q-FeH + + H 2 O f q-HFeOH 2 + f q-FeOH + + H 2 , is exothermic and occurs without activation barrier. In solution, q-FeOH + may attach another proton (if the Coulomb repulsion barrier between the two ions can be overcome) and dissociate to q-Fe 2+ and H 2 O, so the water molecule assists oxidation of a neutral iron atom to Fe 2+ , and two protons can be converted into molecular hydrogen transferring their charge to Fe. The FeH + molecules are also shown to readily react with molecular oxygen, producing FeOOH + without energy barrier. The FeH + + O 2 reaction is more facile than the reaction of FeH + with water due to higher overall exothermicity (68-88 kcal/mol vs 20-34 kcal/mol for FeH + + H 2 O f FeOH + + H 2 ) and a lower barrier for the intermediate reaction step (14-17 vs 35-46 kcal/mol), which can be rate-determining if the reaction occurs in solution. The reaction mechanism involving sequential Fe( 5 D) + H + f q-FeH + , q-FeH + + O 2 f q-HFeO 2 + f q-FeOOH + reactions, followed by dissociation of q-FeOOH + in solution yielding Fe 2+ , may be relevant to the first step of rusting. The calculations showed that electronically excited triplet iron atoms are more reactive with H 2 O. The triplet Fe + H 2 O f Fe-OH 2 f HFeOH reaction is exothermic and has its transition state lying lower in energy than the reactants. No triplet-quintet intersystem crossing was found along the reaction pathway. The mechanism for the Fe + H 2 S reaction in the ground quintet electronic state is found to be similar to that for the reaction with water, but the critical barrier for the formation of the HFeSH intermediate is lower. Because of the reduced endothermicity of the Fe + H 2 S f FeS + H 2 reaction and lower reaction barriers, the reaction of iron atoms with H 2 S is more likely to yield iron sulfide and molecular hydrogen than the reaction with water to produce FeO + H 2 .

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical Study of the Reaction Mechanism of Fe Atoms with H₂O, H₂S, O₂ and H⁺

Mebel

Hwang

2001

J. Phys. Chem. A

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“…20 While chemical reactions of the bare transition metal oxide cations with H 2 have received a significant interest, [24][25][26][27][28][29][30][31][32][33][34][35][36][37] neutral metal oxides have gained much less attention. [38][39][40][41][42][43][44][45][46][47][48][49][50] Recently Zhou et al 51 have reported a combined experimental and theoretical study on the hydrogenation reactions by group V metal dioxides using matrix isolation spectroscopy. These results show a thermodynamically favorable reaction for the dihydrogen cleavage process with small barrier for VO 2 In this work, we present a theoretical study on the reaction mechanism for the dihydrogen activation by neutral group IV metal dioxides (MO 2 , M = Ti, Zr, and Hf) according to the following reaction:…”

Section: Introductionmentioning

confidence: 99%

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

González-Navarrete

Andrés

Berski

2012

J. Phys. Chem. Lett.

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A theoretical investigation using density functional theory (DFT) has been carried out in order to understand the molecular mechanism of dihydrogen activation by means of transition metal dioxides MO 2 (M = Ti, Zr and Hf), according to the following reaction: MO 2 + H 2 → MO + H 2 O. B3LYP/6-311++G(2df,2pd)/SDD methodology was employed considering two possible reaction pathways. As first step the hydrogen activation by M=O bonds yields to metal-oxo hydride intermediates O=MH(OH). This process is spontaneous for all metal dioxides, and the stability of the O=MH(OH) species depends on the transition metal center. Subsequently, the reaction mechanism splits into two paths; the first one takes place passing through the M(OH) 2 intermediates yielding to products whereas the second one corresponds to the direct formation of the product complex OM(H 2 O). A two state reactivity mechanism was found for TiO 2 system whereas for ZrO 2 and HfO 2 no spin-crossing processes were observed. This is confirmed by CASSCF/CASPT2 calculations for ZrO 2 that lead to the correct ordering of electronic states not found by DFT. The results obtained in the present paper for MO 2 molecules are consistent with the observed reactivity on surfaces.

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“…This state must then rearrange to OFeO, before dissociating to FeO + O, 40 giving rise to the bimolecular reaction observed. Because of the high quintet spin multiplicity of Fe and FeO, reaction channel (3d) 16 would be required. However, another explanation for the small value of k 2 is that quintet FeO 2 , which forms initially from Fe + O 2 (a), dissociates rapidly to Fe(a 5 F) + O 2 (X).…”

Section: Discussion and Theoretical Analysismentioning

confidence: 99%

“…15 However, the uncertainty in this bond energy is probably around ±20 kJ mol −1 . 16 Ca + O 2 (a) has three potential channels …”

Section: Introductionmentioning

confidence: 99%

O2(a1Δg) + Mg, Fe, and Ca: Experimental kinetics and formulation of a weak collision, multiwell master equation with spin-hopping

Plane

Whalley

Francés‐Soriano

et al. 2012

The Journal of Chemical Physics

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The first excited electronic state of molecular oxygen, O 2 (a 1 g ), is formed in the upper atmosphere by the photolysis of O 3 . Its lifetime is over 70 min above 75 km, so that during the day its concentration is about 30 times greater than that of O 3 . In order to explore its potential reactivity with atmospheric constituents produced by meteoric ablation, the reactions of Mg, Fe, and Ca with O 2 (a) were studied in a fast flow tube, where the metal atoms were produced either by thermal evaporation (Ca and Mg) or by pulsed laser ablation of a metal target (Fe), and detected by laser induced fluorescence spectroscopy. O 2 (a) was produced by bubbling a flow of Cl 2 through chilled alkaline H 2 O 2 , and its absolute concentration determined from its optical emission at 1270 nm (O 2 (a 1The following results were obtained at 296The total uncertainty in these rate coefficients, which mostly arises from the systematic uncertainty in the O 2 (a) concentration, is estimated to be ±40%. Mg + O 2 (a) occurs exclusively by association on the singlet surface, producing MgO 2 ( 1 A 1 ), with a pressure dependent rate coefficient. Fe + O 2 (a), on the other hand, shows pressure independent kinetics. FeO + O is produced with a probability of only ∼0.1%. There is no evidence for an association complex, suggesting that this reaction proceeds mostly by nearresonant electronic energy transfer to Fe(a 5 F) + O 2 (X). The reaction of Ca + O 2 (a) occurs in an intermediate regime with two competing pressure dependent channels: (1) a recombination to produce CaO 2 ( 1 A 1 ), and (2) a singlet/triplet non-adiabatic hopping channel leading to CaO + O( 3 P). In order to interpret the Ca + O 2 (a) results, we utilized density functional theory along with multireference and explicitly correlated CCSD(T)-F12 electronic structure calculations to examine the lowest lying singlet and triplet surfaces. In addition to mapping stationary points, we used a genetic algorithm to locate minimum energy crossing points between the two surfaces. Simulations of the Ca + O 2 (a) kinetics were then carried out using a combination of both standard and non-adiabatic Rice-Ramsperger-Kassel-Marcus (RRKM) theory implemented within a weak collision, multiwell master equation model. In terms of atmospheric significance, only in the case of Ca does reaction with O 2 (a) compete with O 3 during the daytime between 85 and 110 km.

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The reactions of FeO with O3, H2, H2O, O2 and CO2

Cited by 76 publications

References 24 publications

Theoretical Study of the Reaction Mechanism of Fe Atoms with H₂O, H₂S, O₂ and H⁺

Theoretical Study of the Reaction Mechanism of Fe Atoms with H₂O, H₂S, O₂ and H⁺

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

O2(a1Δg) + Mg, Fe, and Ca: Experimental kinetics and formulation of a weak collision, multiwell master equation with spin-hopping

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The reactions of FeO with O3, H2, H2O, O2 and CO2

Cited by 76 publications

References 24 publications

Theoretical Study of the Reaction Mechanism of Fe Atoms with H2O, H2S, O2 and H+

Theoretical Study of the Reaction Mechanism of Fe Atoms with H2O, H2S, O2 and H+

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

O2(a1Δg) + Mg, Fe, and Ca: Experimental kinetics and formulation of a weak collision, multiwell master equation with spin-hopping

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Theoretical Study of the Reaction Mechanism of Fe Atoms with H₂O, H₂S, O₂ and H⁺

Theoretical Study of the Reaction Mechanism of Fe Atoms with H₂O, H₂S, O₂ and H⁺