Deep reduction behavior of iron oxide and its effect on direct CO oxidation

Chen, Dong; Liu, Xinglei; Wu, Qin; Lü, Qiang; Wang, Xiaoqiang; Shi, Simo; Yang, Yongping

doi:10.1016/j.apsusc.2011.10.092

Cited by 35 publications

(26 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, all the conversation curves suggest that the reduction of OC was not completely reduced into Fe. The same results were likewise obtained from our previous work [42]. In short, deeper reduction degrees show lower reactivity.…”

Section: Tga Experimentssupporting

confidence: 79%

Experimental and Theoretical Study of the Interactions between Fe2O3/Al2O3 and CO

Liang

Chen

2017

Energies

Self Cite

View full text Add to dashboard Cite

Abstract:The behavior of Fe 2 O 3 /Al 2 O 3 particles as oxygen carriers (OCs) for CO chemical looping combustion (CLC) under different reaction temperatures (700 • C, 800 • C, 900 • C, and 1000 • C) were tested in a lab-scale fluidized bed and a thermogravimetric analysis (TGA) unit. The results show that the oxygen carrier presents the highest reactivity at 800 • C, even after 30 cycles of redox reaction in a fluidized bed, while more obvious carbon deposition occurred for the case at 700 • C, and agglomeration for the case at 1000 • C. Moreover, the detailed behavior of the prepared Fe 2 O 3 /Al 2 O 3 particle was detected in the TGA apparatus at different reaction temperatures. Furthermore, temperature-programming TGA experiments were performed to investigate the influence of different CO concentrations and CO/CO 2 concentrations on the reaction between CO and OC during the chemical looping combustion processes. Based on these experimental behaviors of the prepared Fe 2 O 3 /Al 2 O 3 during the CLC of CO, the detailed models and electronic properties of the pure and reduced Fe 2 O 3 /Al 2 O 3 supported the slabs, CO adsorption, and oxidation, and the decomposition reactions on these surfaces were revealed using density functional theory (DFT) calculations which went deep into the nature of the synergetic effect of the support of Al 2 O 3 on the activity of Fe 2 O 3 for the CLC of CO.

show abstract

Section: Tga Experimentssupporting

confidence: 79%

Experimental and Theoretical Study of the Interactions between Fe2O3/Al2O3 and CO

Liang

Chen

2017

Energies

Self Cite

View full text Add to dashboard Cite

show abstract

“…CH 4 From the analysis of the data collected in Table 1, it can be concluded that most of the works produced to date do not provide sufficient information with which to model a CLC system using an Fe-based material as an oxygen carrier. Theoretical kinetic studies, relevant from a basic-science point of view, have been also conducted to investigate the mechanisms of interaction between reacting gases and Fe-based oxygen carriers [39][40][41][42][43][44][45][46][47][48], suggesting that the Fe 2 O 3 -support interaction influences material reactivity. However, these works do not provide enough practical information for CLC system design and simulation.…”

Section: Introductionmentioning

confidence: 99%

Kinetic determination of a highly reactive impregnated Fe2O3/Al2O3 oxygen carrier for use in gas-fueled Chemical Looping Combustion

Cabello

Abad

Garcı́a-Labiano

et al. 2014

Chemical Engineering Journal

112

View full text Add to dashboard Cite

The objective of this work was to determine the kinetic parameters for reduction and oxidation reactions of a highly reactive Fe-based oxygen carrier for use in chemical looping combustion (CLC) of gaseous fuels containing CH 4 , CO and/or H 2 , e.g. natural gas, syngas and PSA-off gas. The oxygen carrier was prepared by impregnation of iron on alumina. The effect of both the temperature and gas concentration was analysed in a thermogravimetric analyser (TGA).The grain model with uniform conversion in the particle and reaction in grains following the shrinking core model (SCM) was used for kinetics determination. It was 2 assumed that the reduction reactions were controlled by two different resistances: the reaction rate was controlled by chemical reaction in a first step, whereas the mechanism that controlled the reactions at higher conversion values was diffusion through the product layer around the grains. Furthermore, it was found that the reduction reaction mechanism was based on the interaction of Fe 2 O 3 with Al 2 O 3 in presence of the reacting gases to form FeAl 2 O 4 as the only stable Fe-based phase. The reaction order values found for the reducing gases were 0.25, 0.3 and 0.6 for CH 4 , H 2 and CO, respectively, and the activation energy took values of between 8 kJ mol -1 (for H 2 ) and 66 kJ mol -1 (for CH 4 ). With regard to oxidation kinetics, the reacting model assumed a reaction rate that was only controlled by chemical reaction. Values of 0.9 and 23 kJ mol -1 were found for reaction order and activation energy, respectively.Finally, the solids inventory needed in a CLC system was also estimated by considering kinetic parameters. The total solids inventory in the CLC unit took a minimum value of 150 kg MW -1 for CH 4 combustion, which is a low value when compared to those of other Fe-based materials found in the literature.

show abstract

“…When Ni atom was added to H 2 /α-Fe 2 O 3 (001) system, which causes the inclination angle between H 2 molecule and the α-Fe 2 O 3 (001) surface, thus leading to the change of surface charge distribution of α-Fe 2 O 3 (001) [21,25]. Compared with H 2 /α-Fe 2 O 3 (001) system, the average bond length of Fe-O in (H 2 + Ni)/α-Fe 2 O 3 (001) system increased from 2.0253 to 2.0258 Å, indicating that α-Fe 2 O 3 (001) in (H 2 + Ni)/α-Fe 2 O 3 (001) system has been activated, which will be more conducive to the adsorption of H 2 molecules on α-Fe 2 O 3 (001) surface [26]. Figure 3 shows the density of states (DOS) of α-Fe 2 O 3 (001) surface and H 2 molecules of H 2 /α-Fe 2 O 3 (001) system in the presence or absence of Ni atom.…”

Section: Computational Results Of H 2 Molecule On the α-Fe 2 O 3 (001mentioning

confidence: 99%

Combined Density Functional Theory and Reduction Kinetics Investigation of Enhanced Adsorption of Hydrogen onto Fe2O3 by Surface Modification with Nickel

Zhang

Wei

et al. 2019

Metals

View full text Add to dashboard Cite

Based on the density functional theory, the geometric structure, adsorption energy and density of states of H 2 /α-Fe 2 O 3 (001) system and (H 2 + Ni)/α-Fe 2 O 3 (001) system were determined. The results showed that the absolute value of adsorption energy between H 2 molecule and α-Fe 2 O 3 (001) surface and the bond length of H 2 molecule were increased by the presence of Ni atom. The presence of Ni atom promotes the adsorption of H 2 molecule on α-Fe 2 O 3 (001) surface. Reduction behavior of iron and nickel oxides in H 2 atmosphere was determined by thermogravimetric analysis. The samples included Fe 2 O 3 , Fe 2 O 3 -NiO and Fe 2 O 3 -Ni systems. The effect of Ni and NiO on the reduction behavior of Fe 2 O 3 was investigated. The ease of reduction within the following three systems decreases sequentially: Fe 2 O 3 -Ni > Fe 2 O 3 -NiO > Fe 2 O 3 . The activation energy of Fe 2 O 3 -Ni, Fe 2 O 3 -NiO and Fe 2 O 3 systems at two temperature stages (viz. < 400 • C and > 400 • C) were 172 kJ·mol −1 , 197 kJ·mol −1 and 263 kJ·mol −1 respectively.

show abstract

Deep reduction behavior of iron oxide and its effect on direct CO oxidation

Cited by 35 publications

References 50 publications

Experimental and Theoretical Study of the Interactions between Fe2O3/Al2O3 and CO

Experimental and Theoretical Study of the Interactions between Fe2O3/Al2O3 and CO

Kinetic determination of a highly reactive impregnated Fe2O3/Al2O3 oxygen carrier for use in gas-fueled Chemical Looping Combustion

Combined Density Functional Theory and Reduction Kinetics Investigation of Enhanced Adsorption of Hydrogen onto Fe2O3 by Surface Modification with Nickel

Contact Info

Product

Resources

About