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Reduction of Fe2O3 with hydrogen

Article  in  Applied Catalysis A General · June 2010

DOI: 10.1016/j.apcata.2010.04.003

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Accepted Manuscript

Title: Reduction of Fe2 O3 with hydrogen

Authors: Jerzy Zieliński, Ilona Zglinicka, Leszek Znak,

Zbigniew Kaszkur

PII: S0926-860X(10)00264-4
DOI: doi:10.1016/j.apcata.2010.04.003
Reference: APCATA 12529

To appear in: Applied Catalysis A: General

Received date: 16-12-2009

Revised date: 29-3-2010
Accepted date: 5-4-2010

Please cite this article as: J. Zieliński, I. Zglinicka, L. Znak, Z. Kaszkur,

Reduction of Fe2 O3 with hydrogen, Applied Catalysis A, General (2008),
doi:10.1016/j.apcata.2010.04.003

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*Graphical Abstract

Reduction of Fe2O3 with hydrogen

Jerzy Zieliński1,2*, Ilona Zglinicka2, Leszek Znak1, Zbigniew Kaszkur1
1
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224
Warsaw, Poland
2
Warsaw University of Technology, Institute of Chemistry, Łukasiewicza 17, 09­400 Płock,
Poland

The reduction of Fe2O3 in hydrogen proceeds:

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 in two steps, Fe2O3→Fe3O4 →Fe, in dry 5,8%H2+Ar mixture, but

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 in three steps, Fe2O3→Fe3O4→”FeO”→Fe, in wet 5,8%H2+Ar+H2O mixture.

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*Manuscript

Reduction of Fe2O3 with hydrogen

Jerzy Zieliński1,2*, Ilona Zglinicka2, Leszek Znak1 Zbigniew Kaszkur1

1
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224
Warsaw, Poland
2
Warsaw University of Technology, Institute of Chemistry, Łukasiewicza 17, 09­400 Płock,

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Poland

* Corresponding author, email: jerzy@ichf.edu.pl

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Key words: reduction of iron oxide, temperature-programmed reduction, TPR, XRD, Fe2O3,

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hematite, magnetite, wustite, iron.

Abstract an
The reduction of Fe2O3 with hydrogen was studied. The thermodynamic analysis of
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the process implied that temperature-programmed reduction of the oxide should proceed in
three steps, i.e. Fe2O3→Fe3O4→”FeO”→Fe, at X H 2O X H 2 ratio over 0.35, but in two
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steps, i.e. Fe2O3→Fe3O4→Fe, below that value. The idea was verified by TPR and XRD
studies. Generally, the examinations confirmed the suggestions. The reduction is three-step
reaction at high X H 2O X H 2 ratio, but two-step reaction at low that ratio. Additionally, it
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was revealed that at extremely low X H 2O X H 2 ratio the TP reduction is a one-step reaction,
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i.e. Fe2O3→Fe.
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Introduction

The reduction of Fe2O3 with hydrogen was a subject of numerous studies [1-7], but
there still have been differing opinions concerning the reaction route, even for unsupported
samples. Thus, there are TPR studies, which point to the two-step mechanism, i.e.
Fe2O3→Fe3O4→Fe [1­4], and there are reports indicating the three-step mechanism, i.e.
Fe2O3→Fe3O4→”FeO”→Fe [5­7]. The aim of this examination is to clarify mechanism of
Fe2O3 reduction. This knowledge is of great importance when TPR method is applied to
characterization of iron supported catalysts.

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 TPR method is a relatively simple technique, but analysis of the experimental results
is often difficult. The problem is that the obtained TPR profile depends not only on the type
of the examined sample, but also on the experimental parameters of the measurements such
as weight of the sample, composition and flow rate of the reducing mixture, and the
temperature ramp rate [2,7]. All these parameters collectively influence two essential
reduction parameters, i.e. H2 and H2O concentrations, which in turn affect the reduction
rate. The problem of H2 depletion in the course of TPR tests has been revealed and

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extensively discussed by Monti and Baiker [8]. As a result, they proposed that the
experimental parameter of TPR test should be selected so as to get only a small decline of

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H2 concentration. In contrast to that question, insufficient attention has still been paid to the
effect of water. Water is the inevitable product in TPR experiment and its concentration

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generally changes in the course of TPR test from a negligibly small value to a significant
value, i.e. a few orders of magnitude, and may radically change position and shape of the
recorded TPR profile [2, 9-11]. an
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Experimental

Apparatus
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The examinations were carried out in a glass flow system [12], equipped with a
gradientless microreactor [13]. Two H2+Ar mixtures (83.6 and 5.8 mol % H2) of high purity
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(99.999 %) were used in this study. The gas stream required was fed to the measuring
system by a selecting valve and, before entering the reactor, it was additionally purified
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from traces of oxygen and water in MnO/SiO2 column. The gas stream leaving the reactor
was examined with the TCD cell and the results were collected with a computer-controlled
system.
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The TPR studies were supplemented with XRD examinations. The measurements
were carried out using powder diffractometer D5005 manufactured by Siemens (Bruker
AXS) using Ni-filtered Cu-K radiation. A part of these examinations were performed in
situ in the course of TP reduction using a home made metal camera [14] and a position
sensitive detector CPS120 manufactured by INEL.

The ex situ XRD measurements of some samples were performed when their TP
reduction continued to high temperature. In this case, the reduction was carried out in the
flow system described above, whereupon the sample was cooled down, flushed with a He

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stream and passivated with small O2 pulses. The XRD studies of these samples were
performed with the use of standard scintillation detector in a step scan mode.

Measurement procedure

The raw material for the TPR tests was Fe2O3 powder p.a. (Merck, No. 4625270).
The XRD phase analysis of the oxide demonstrated hexagonal Fe2O3 phase. Total surface

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area of the material was 2.2 m2/g, which corresponds to particle size of 0.5 m. Scanning

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electron microscope showed a sharp particles distribution with an average diameter of about

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0.4 m.

Prior to the TPR test, the examined sample was dried in situ in He stream (400 ºC,

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30 cm3/min, 30 min). Then the reactor with the sample was cooled down to room
temperature whereupon the stream was replaced with one of the H2+Ar mixtures of 30
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cm3/min. Generally, the TPR measurements were carried out at 5ºC/min. The stream leaving
the reactor was dried in a trap at –78 ºC and consumption of hydrogen was measured. After
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that, the reactor with the examined sample was by-passed and calibration of the system was
performed, introducing well-defined H2 pulse into the H2+Ar stream.

A part of the TPR measurements presented in this communication was carried out
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with H2+Ar mixtures saturated with water at a selected temperature in order to get a desired
H2O concentration. These experiments are referred to as “wet” in the subsequent parts of
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this communication, in contrast with the “dry” experiments where the unsaturated H2+Ar
mixture was used.
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Results and discussion

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Thermodynamics of iron–iron oxide system in water–hydrogen atmosphere

Figure 1 presents the equilibrium iron–iron oxide phase diagram in water–hydrogen

atmosphere. The relations were derived from the free enthalpy data measured by Rau [15]
and published by Barin and Knacke [16]. The lines, marked with KA, KB, KB1 and KB2,
represent equilibrium constants of the following reactions:

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 X H 2O
A 3Fe 2 O 3  H 2  2Fe 3O 4  H 2 O KA 
XH2

X H2O
B 0.25 Fe 3O 4  H 2  0.75 Fe  H 2 O KB 
X H2

X H2O
B1 1.202 Fe 3O 4  H 2  3.808 Fe 0.947O  H 2 O K B1 
X H2

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X H2O
Fe 0.947O  H 2  0.947 Fe  H 2 O K B2 

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B2
X H2

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Fig.1. Iron–iron oxide phase diagram in water–hydrogen atmosphere. Solid lines

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express the equilibrium state of the system and thin, dotted lines show the equilibrium state
for selected reactions. Hereafter “FeO” denotes wustite, thermodynamically stable
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compound of composition Fe0.947O [15]. The eutectoid point is at T  571 C and

X H 2O X H 2 ratio  0.35 .

The relations presented in Fig.1 allow to anticipate the reaction route in the course
of TP reduction of Fe2O3. They show that:
 The reduction Fe2O3→Fe3O4, expressed by line a in Fig.1, is thermodynamically
possible even at high X H 2O X H 2 ratio.

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 The reduction Fe3O4→Fe may occur only at sufficiently low X H 2O X H 2 ratio, and the

reduction route should depend on X H 2O X H 2 ratio in a gas phase.

 at X H 2O X H 2 below ca. 0.35, line b’, the reduction should be a one-step reaction,

Fe3O4→Fe, and
 at X H 2O X H 2 over ca. 0.35, line b”, the reduction should be a two-step reaction:

Fe3O4→”FeO”→Fe.

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TPR examinations of Fe2O3

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Figure 2 presents preliminary TPR tests of Fe2O3, in which the two reducing H2+Ar

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mixtures, H2 concentration of 83.6 or 5.8 mol %, and two sizes of the examined sample, 5
or 25 mg, were used. The results demonstrate a strong effect of experimental parameters on
the TPR profiles for Fe2O3 and thereby they justify the diverse opinions on the reaction
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mechanism. Referring back to the results in Fig.2, it is important that these profiles are
similar to the respective profiles, as reported previously [1-4, 7]. Thus:
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 profile 1, obtained for 5 mg sample and 83.6%H2+Ar mixture is similar to the profiles
obtained by Wimmers et al. for small samples and 67%H2+Ar mixture [2],
 profile 2 is much the same as the one obtained by Munteanu et al. [3], and also the one
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obtained by Kock et al. [1], and identical with the profile obtained in pure H2 by
Jóźwiak et al. [7],
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 profile 3 is similar to the profiles reported by Lin et al. [4],

 profile 4 is very similar to the profile obtained by Jóźwiak et al. [7] for 15 mg sample in
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5%H2+Ar mixture.
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Fig.2.The effect of experimental conditions on TPR profiles recorded for F2O3

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Closer inspection of the results in Fig.2 leads to two important statements: (i) H2
concentration decreases only slightly in these experiments, which suggests that the change
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does not affect the reduction rate and (ii) the five-fold increase of the size of the examined
sample increases H2O evolution only two-fold, which, indicates that water strongly retards
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Fe2O3 reduction.

Figure 3 presents the effect of water, 0.6% and 1.2% in 5.8%H2+Ar mixture on TP
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reduction of 5 mg Fe2O3 sample. In order to attain a better clarity, the profiles are shown
only in terms of H2O concentration/production. The obtained results show a complex effect
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of water on the reaction. For the dry test, the TPR profile consists of two peaks of H2O
production,  and , while for the wet tests, the  peak splits into two separate peaks, 1
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and 2, appearing at considerably higher temperature.

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Page 7 of 18
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Fig.3. The effect of water on TP reduction of 5 mg Fe2O3 sample

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Fig.4. The effect of water on TP reduction of 25 mg Fe2O3 sample

The effect of water on TP reduction of 25 mg Fe2O3 sample in 5.8%H2+Ar mixture

(Fig.4) is similar to that for 5 mg sample (Fig.3). However, due to large size of the sample
and, as a result, large H2O production, the 1 and 2 peaks overlap with each other and
appear at higher temperature.

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 Supplementary data on Fe2O3 reduction were obtained using the 83.6%H2+Ar
mixture (see Fig.5). In this case even for: (i) large samples of 50 mg, (ii) large temperature
ramp of 10ºC/min and (iii) large concentration of water in the reducing mixture of 2.5%, the
TP tests suggest the two-step reduction route.

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Fig.5. The temperature-programmed reduction of 50 mg Fe2O3 sample in
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83.6%H2+Ar mixture
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The TPR results in Figs.3-5 appear to confirm the thermodynamic suggestions from
Fig.1. that: (i) at low X H 2O X H 2 ratio the Fe2O3 reduction occurs as a two-step reaction
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and (ii) at high X H 2O X H 2 ratio the reduction occurs as a three-step reaction.

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The predicted mechanism of the reduction was verified by quantitative analysis of

the spectra in Figs.3-5. The integration of the profiles allowed to determine the quantity of
water produced during the subsequent stages of the reduction. These values, related to the
total amount of water produced for the entire experiment, are shown in Table 1. Next to the
experimental results, Table 1 also shows the theoretical values of H2O production for each
stage, assuming the following steps of Fe2O3 reduction:
 1 2
FeO1.500  FeO1.333  FeO1.056  Fe

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Table 1. Fraction of water produced during the subsequent stages of Fe2O3 reduction

Exp. Fraction of water

Experiment
No  peak 1 peak 2 peak
5 5 mg ~0,087 ~0.913
6 5 mg, 0.6%H2O 0,092 ~0.219 ~0.689

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7 5 mg, 1.2%H2O 0,116 0,194 0,689
8 25 mg 0,101 0,899

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9 25 mg, 0.6%H2O 0,105 ~0,192 ~0.703
10 25 mg, 1.2% H2O 0,107 0,189 0,704

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11 50 mg ~0,097 ~0,903
12 50 mg, 2.5%H2O 0,111 0,889

Theoretical values 0,111 an 0,185

0.889
0,704
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The comparison in Table 1 demonstrates excellent compliance of experimentally
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determined size of individual H2O peak with the theoretical values which confirms the two
following routes of Fe2O3 reduction:
 
 at low X H 2O X H 2 ratio the two-step route: Fe2O3  Fe3O4 
 Fe , and
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 at high X H 2O X H 2 ratio the three-step route:

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 1 2
Fe2 O3  Fe3O 4  " FeO"  Fe .
Moreover, a closer inspection of the profile 7 in Fig.3 implies that pure Fe3O4 and
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“FeO” intermediate phases appeared during the experiment at 500 and 655 ºC, respectively.

XRD study

The examinations were performed for the samples reduced ex situ or in situ in the
way simulating TPR tests of 5 mg Fe2O3 samples. Namely, 15 mg Fe2O3 samples and
three-fold greater flow rate of reducing mixture were used in the reduction in order to attain
possibly the same route of the reaction. The ex situ TP reduction of 15 mg Fe2O3 sample in
the 5.8%+Ar+1.2%H2O mixture (90 cm3/min) gave the same result as the one shown in

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Fig.3 (curve 7), which indicates the same route of the reduction. At the same time this result
indicated that an external mass transfer does not influence the reduction.

Figure 6. shows XRD studies of the samples reduced ex situ in the

5.8%H2+Ar+1.2%H2O mixture. The terminal temperatures of the TP reduction were chosen
on the basis of the experiment 7 in Fig.3 so as to demonstrate that pure iron phases are
consecutively formed in the course of the TPR test. The obtained spectra are identical with
the reported spectra of hexagonal Fe2O3, cubic Fe3O4, cubic “FeO” and cubic Fe [17],

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which confirms the three-step model of Fe2O3 reduction in the 5.8%H2+Ar+1.2%H2O
mixture.

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Fig.6. The XRD patterns of Fe2O3 reduced ex situ in the 5.8%H2+Ar+1.2%H2O

mixture. The numbers next to the spectra stand for the terminal temperature of TP
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reduction.

Figure 7 presents the XRD spectra recorded in situ during the TP reduction
simulating the exp.5 in Fig.3. In this case, the three phases are observed, hexagonal Fe2O3,
cubic Fe3O4, and cubic Fe, and no cubic “FeO” phase is recorded, which is in line with
equilibrium thermodynamic suggestions. These results show that at low H2O concentration
(occurring only as a result of Fe2O3 reduction) Fe2O3 reduction follows the two-step
mechanism.

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Page 11 of 18
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Fig.7. The XRD spectra recorded during the TP reduction of Fe2O3 in the
5.8%H2+Ar mixture. The numbers tagging the reflections stand for: 1  hexagonal Fe2O3, 2
– cubic Fe3O4 and 4  cubic Fe. Two large reflections of Fe2O3 and of Fe3O4 (2 theta about
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35.5 and 61.5 deg) are not marked as their position is close to each other and they do not
show the phase transition clearly.
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Figure 8 presents the XRD spectra recorded in situ during the TP reduction
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simulating the exp.1 in Fig.2. In this case, only two phases are recorded, hexagonal Fe2O3,
and cubic Fe. These results demonstrate that at low H2O concentration but at high H2
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concentration the reduction follows a direct transformation of Fe2O3 into metal iron.
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Fig.8. The XRD spectra recorded during the TP reduction of Fe2O3 in the
83.6%H2+Ar mixture. The numbers tagging the reflections stand for: 1  hexagonal Fe2O3
and 4 – cubic Fe.
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Discussion

The above experimental results indicate that water: (i) does not affect Fe2O3→Fe3O4
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reaction, (ii) moderately retards Fe3O4→”FeO” reaction, and (iii) strongly retards
”FeO”→Fe reaction.
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The effect of water on the reduction of Fe2O3 appears clearer, if we compare the
reaction quotient, i.e. Q  X H 2O X H 2 ratio in the course of the reduction, with the
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equilibrium constants calculated for each individual reaction (see Figs.9-11). Generally, the
comparisons confirm the thermodynamic suggestions, however, some experimental results
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seem incompatible with thermodynamic data. Namely, the profile 6 in Fig.9 and profile 9 in
Fig.10 suggests wustite formation below 571 ºC though the thermodynamics predicts the
formation of metallic iron. In relation to this issue, it should be kept in mind that admittedly,
the equilibrium thermodynamic relations in Figs.9-11 show that Fe3O4→Fe reaction is the
most favourable below 571 ºC, but still, the Fe3O4→”FeO” reaction is also possible, and it
is the kinetics to decide which of the two possible reactions will actually proceed.

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Fig.9. Equilibrium constant and quotient of Fe2O3 reduction for 5 mg Fe2O3 sample

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Fig.10. Equilibrium constant and quotient of Fe2O3 reduction for 25 mg Fe2O3

sample

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Page 14 of 18
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Fig.11. Equilibrium constant and quotient of Fe2O3 reduction for 50 mg Fe2O3
sample
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The formation of “FeO” phase below 571 ºC was evidenced by ex situ XRD
examination of the sample reduced in the way simulating exp.6 in Fig.3 (also in Fig.9). The
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TP reduction was terminated at 561 ºC, i.e. 10 ºC below the eutectoid point. The obtained
spectrum (see Fig.12) shows, next to cubic Fe3O4 phase, considerable quantity of “FeO”
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phase and traces of Fe phases. Closer analysis of the spectrum shows that the “FeO”
reflections are shifted to low angle by 0.3-0.5 deg in comparison with “FeO” reflections in
Fig.6, which suggests slightly lower content of oxygen in this intermediate.
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 Fig.12. The XRD patterns of Fe2O3 reduced ex situ in the 5.8%H2+Ar+0.6%H2O
mixture. Terminal temperature of the sample TP reduction was 561 ºC. The numbers
tagging the reflections stand for: 2 – cubic Fe3O4, 3 – cubic “FeO” and 4  cubic Fe.

The formation of “FeO” below eutectoid point implies that Fe3O4→”FeO” reaction
is relatively fast and the appearing " FeO" is immediately reduced to metal iron at small

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H2O concentration, but it forms a stable phase at large H2O concentration. Regular position

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of  and 1 peaks in relation to KB1 line (see Figs.9, 10, 11) appears to support the

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suggestion. Therefore, it is supposed that the two-step Fe2O3 reduction observed at low
X H 2O X H 2 ratio is in fact the three-step reaction, Fe2O3→Fe3O4→”FeO”→Fe, in which the

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third step, i.e. ”FeO”→Fe reaction, is fast and thereby “FeO” phase is not recorded by
XRD.
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The two-step route of Fe2O3 reduction in 83.6%H2+Ar mixture (see Fig.5) is easier
to understand, if we compare quotient for these tests with the equilibrium constants of the
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reduction (see Fig.11). The comparison demonstrates that the application of rich H2+Ar
mixture strongly favours Fe3O4 reduction. It is particularly significant that the low-
temperature side of the  peak coincides with the KB1 line, which implies that
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Fe3O4→”FeO” reaction occurs nearly in the equilibrium state and the next reaction, i.e.
”FeO”→Fe, is very fast.
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Assuming that Fe3O4→”FeO” reduction occurs in the equilibrium state in the

83.6%H2+Ar mixture, the thermodynamic analysis indicates that for 5 mg sample the
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Fe3O4→”FeO” reaction should occur at low temperature of about 400 ºC, i.e. the
temperature close to Fe2O3→Fe3O4 reduction temperature. This explains the one-step
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mechanism of the Fe2O3 reaction, which was demonstrated by TPR test (profile 1 in Fig.2)
and XRD study (Fig.8).

Conclusions
The temperature-programmed reduction of Fe2O3 with hydrogen depends strongly
on a number of experimental parameters, which affect X H 2O X H 2 ratio in the gas phase, the

crucial parameter of the reaction.

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Page 16 of 18
 Qualitatively, temperature-programmed reduction of Fe2O3 with hydrogen proceeds
in line with thermodynamic suggestions, i.e. it is three-step reaction at large
X H 2O X H 2 ratio, and two-step reaction at low X H 2O X H 2 ratio.

A comparison of the experimental results with thermodynamic relations (Figs.9-11)

showed that due to kinetic reasons the three-step route of Fe2O3 reduction proceeds also
beyond the limits indicated by equilibrium thermodynamic, i.e. at X H 2O X H 2 ratio below

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0.35 and at temperature below 571 ºC.

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Additionally, it was evidenced that at extremely low X H 2O X H 2 ratio the TR

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reduction of Fe2O3 proceeds as a one-step reaction, Fe 2 O 3  Fe .

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Page 17 of 18
 References
1. J.H.M. Kock, H.M. Fortuin, J.W. Geus, J. Catal. 96 (1985) 261-275.
2. G.J. Wimmers, P. Arnoldy, J.A. Moulijn, J. Phys. Chem. 90 (1986) 1331-1337.
3. G. Munteanu, L. Ilieva, D. Andreeva, Termochim. Acta 291 (1997) 171-177.
4. H.Y. Lin, Y.W. Chen, Ch.P. Li, Termochim. Acta 400 (2003) 61-67.

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5. A. Venugopal, J. Aluha, D. Mogano, M.S. Scurrel, Appl. Catal. A: Gen. 245 (2003)

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149-158.

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6. A. Venugopal, M.S. Scurrel, Appl. Catal. A: Gen. 258 (2004) 241-249.
7. W.K. Jóżwiak, E. Kaczmarek. T.P. Maniecki, W. Ignaczak, W. Maniukiewicz,

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Appl. Catal. A: Gen. 326 (2007) 17-27.
8. D.A.M. Monti, A. Baiker, J. Catal. 83 (1983) 323-335.
9. J. Zieliński, Catal. Lett. 12 (1992) 389-394.
10. J. Zieliński, Catal. Lett. 31 (1995) 47-56.
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11. J. Zieliński, J. Chem. Soc. Faraday Trans. 93 (1997) 3577-3580.
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12. J. Zieliński, J. Catal. 76 (1982) 157-163.
13. J. Zieliński, React. Kinet. Catal. Lett. 17 (1981) 69-75.
14. J. Zieliński, A. Borodziński, Appl. Catal. 13 (1985) 305-310.
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15. H. Rau, J. Chem. Thermodyn. 4 (1972) 57-64.

16. L. Barin, O. Knacke, Thermochemical properties of inorganic substance, Springer-
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Verlag, 1973.
17. Powder Diffraction, Joint Committee on Powder Diffraction Standards, ICDD,
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1999: Fe2O3 – Card 86-0550, Fe3O4 – Card 85-1436, “FeO” – Card 85-0625, Fe –
Card 851410.
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