The catalytic activity of Fe-containing SiBEA zeolites in Fischer-Tropsch synthesis

Article abstract of DOI:10.1016/j.cattod.2015.02.017

This work is focused on catalytic activity of Red-C-Fe_xSiBEA zeolites in Fischer-Tropsch synthesis. The Fe-containing zeolites were obtained by two-step post-synthesis method, which allowed incorporating the metal ions into zeolite framework and in this way to obtain materials with new physicochemical and catalytic properties. The TPR-H₂ studies allowed to determine the reducibility of different kinds of iron species present in C-Fe_xSiBEA zeolites. The catalytic investigations indicated that the most active catalyst in FTS is Red-C-Fe₂₀SiBEA, which achieved the CO conversion of 70% and selectivity towards liquid products of 71%. The isoalkanes, n-alkanes, olefins and oxidative products (alcohols, ketones and aldehydes) were identified among of liquid products. The most probably reason of catalysts deactivation is coke formation, which amount, calculated on the base of DTG-DTA data, was 7% for Red-Fe_4.0SiBEA, 20% for Red-C-Fe₁₀SiBEA and 35% for Red-C-Fe₂₀SiBEA.

Full text of DOI:10.1016/j.cattod.2015.02.017

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The catalytic activity of Fe-containing SiBEA zeolites in
Fischer–Tropsch synthesis
a,∗
a
a
Karolina A. Chalupka , Waldemar Maniukiewicz , Pawel Mierczynski ,
a
a
b,c,∗∗
Tomasz Maniecki , Jacek Rynkowski , Stanislaw Dzwigaj
Lodz University of Technology, Institute of General and Ecological Chemistry, Zeromskiego 116, 90-924 Lodz, Poland
Sorbonne Universités, UPMC Univ Paris 06, UMR 7197, Laboratoire de Réactivité de Surface, F-75005 Paris, France
CNRS, UMR 7197, Laboratoire de Réactivité de Surface, F-75005 Paris, France
a
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
This work is focused on catalytic activity of Red-C-Fe SiBEA zeolites in Fischer–Tropsch synthesis. The
x
Received 2 November 2014
Received in revised form 28 January 2015
Accepted 9 February 2015
Available online xxx
Fe-containing zeolites were obtained by two-step post-synthesis method, which allowed incorporating
the metal ions into zeolite framework and in this way to obtain materials with new physicochemical
and catalytic properties. The TPR-H2 studies allowed to determine the reducibility of different kinds of
iron species present in C-FexSiBEA zeolites. The catalytic investigations indicated that the most active
catalyst in FTS is Red-C-Fe20SiBEA, which achieved the CO conversion of 70% and selectivity towards
liquid products of 71%. The isoalkanes, n-alkanes, olefins and oxidative products (alcohols, ketones and
aldehydes) were identified among of liquid products. The most probably reason of catalysts deactivation
is coke formation, which amount, calculated on the base of DTG-DTA data, was 7% for Red-Fe4.0SiBEA,
20% for Red-C-Fe10SiBEA and 35% for Red-C-Fe20SiBEA.
Keywords:
Fischer–Tropsch synthesis
Iron
BEA zeolite
Synthesis gas
©
2015 Published by Elsevier B.V.
1
. Introduction
contrast to cobalt catalysts. The huge favour of iron catalysts using
in FTS is their high activity even when the syngas is derived from
coal and biomass sources which have a very low CO/H2 ratio (≤1)
[3,5].
During Fischer–Tropsch synthesis (FTS), syngas (mixture of CO
and H ) is catalytically converted into wide spectrum of hydro-
2
carbons chain [1,2]. This process is heterogenous reaction, where
substrates are gaseous, products are present in gas and liquid phase
and catalyst is solid [3]. As industrial catalysts of FTS, mainly cobalt
However, despite of many advantages, the iron-based catalysts
possess few unfavourable properties such as rapid deactivation by
coke deposition and sintering and high costs of their regeneration
[3,5]. These disadvantages are still challenge in catalysts design.
It seems that choice of proper support with high specific sur-
face area could prevent partially the high deactivation rate. The
very good support for iron catalysts can be zeolites. They have high
specific surface area, which ensures small size of metal nanoparti-
cles and their good dispersion [6,7], what makes them very useful
in catalysis [7]. These properties of zeolites can lead to limit chain
growth and form of lighter products. Moreover, the acidity of these
materials may catalyze the secondary cracking, isomerization and
aromatization of primary FT products which contribute to improve-
ment of the products distribution. The many zeolites were tested
as supports of iron, among them can be mentioned: NaY, NaX,
Na-ß, Na-MOR and Na-ZSM-5 [8]. It is shown that the acidity of
zeolites has influence on the product selectivity in FTS. Bessel [9]
has found that cobalt supported on ZSM-5, Y and MOR zeolites,
SiO , Al O and bentonite showed similar selectivity to methane
and iron supported on Al O3 or SiO2 are used. Depending on the
2
process conditions and the kind of catalysts used, the reaction prod-
ucts spectrum can be shifted to alkenes or alcohols [3,4].
The low costs of iron, its wide availability and its high activ-
ity to Water–Gas-Shift reaction (WGS) are mentioned among the
advantages of the application of iron catalysts in Fischer–Tropsch
process. In the case of WGS process, the iron catalyzes the reac-
tion between water and carbon monoxide and during this process
the carbon dioxide and hydrogen are produced. Moreover, dur-
ing FTS over iron catalysts the wider spectrum of liquid products,
including n-hydrocarbons, alcohols and alkenes can be formed, in
∗
Corresponding author. Tel.: +48 42 631 31 34.
Corresponding author at: Sorbonne Universités, UPMC Univ Paris 06, UMR 7197,
∗
∗
2
2
3
Laboratoire de Réactivité de Surface, F-75005 Paris, France. Tel.: +33 1 44 27 21 13.
E-mail addresses: karolina.chalupka@p.lodz.pl (K.A. Chalupka),
stanislaw.dzwigaj@upmc.fr (S. Dzwigaj).
and carbon dioxide, however the distribution of higher hydro-
carbons is strongly depended on the support acidity. The highest
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0
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selectivity towards gasoline-range hydrocarbons showed ZSM-5,
the most acidic type of zeolite [9].
concentrated by SPE method on octadecyl columns C18. Before
extraction each of column was preconditioned with 2 mL of n-
hexane. After this process 1 mL of liquid products samples were
injected on column and then it was washed with 2 mL of n-hexane.
The aim of this work was the investigation of catalytic activity
in Fischer–Tropsch synthesis of iron catalysts based on BEA zeolite,
prepared by two-step postsynthesis method. This method allows
incorporating of transition metal ions into zeolite framework [10]
and in this way modelling of new catalytic centres. This method
allows also modelling acidic sites in BEA zeolite.
−
1
GC–MS analysis were carried out in helium flow (1.0 mL min ) in
◦
temperature range 70–250 C with linear temperature increase of
◦
−1
3
8 C min . The volume of analyzed sample was 1 mm .
The quantitative analysis of CO conversion (KCO) and selectiv-
ity towards CO2 (SCO2 ), CH4 (SCH4 ) and liquid products (SLP) were
calculated in the following way:
2
. Experimental part
SCO in − SCO ari
2.1. Samples preparation
KCO =
× 100%
S
CO in
The FexSiBEA samples were obtained by two-step postsynthe-
sis method (where x = 4, 10 and 20 wt% of Fe) described earlier by
Dzwigaj et al. [11].
XCH × 100%
i
4
SCH4
=
/F
X
CH4 out
To prepare these samples, firstly, the TEABEA zeolite was treated
−
1
◦
X
s
× KCO
in a 13 mol L
HNO3 aqueous solution (4 h, 80 C) to obtain a
CH4
XCH
=
out
4
dealuminated and organic-free SiBEA support (Si/Al = 1300) with
vacant T-atom sites (where T = Al). SiBEA was then separated by
100%
centrifugation, washed with distilled water and dried overnight at
XCO2 i × 100%
S
CO2
=
/F
◦
8
0 C. To incorporate iron into vacant T-atom sites, 2 g of SiBEA
XCO
out
2
◦
was stirred under aerobic conditions at 25 C for 24 h in 200 mL of
Fe(NO ) ·9H O aqueous solution (pH = 2.4–2.6) with different con-
3
3
2
XCO × KCO
s
2
X
=
centrations to obtain the solids with various Fe content [10]. Then,
CO2 out
1
00%
◦
the suspensions were stirred for 2 h at 80 C until water was evapo-
◦
where KCO – CO conversion; SCO in – the peak’s surface of CO on
inlet before reaction (standard); SCO ari – the peak’s surface of CO
after reaction; (SCH4 ) – selectivity towards CH ; (S
rated and the resulting solids were dried in air at 80 C for 24 h and
labelled as FexSiBEA. Then, the solids were calcined in air at 500 C
◦
) – selectiv-
4
CO2
for 3 h and labelled C-FexSiBEA.
ity towards CO2; XCH – the peak’s surface of CH4 formed during
Before FT reaction tests, C-FexSiBEA were reduced in situ under
4
i
◦
reaction; XCO2 i – the peak’s surface of CO2 formed during reac-
atmospheric pressure in flow of 95% H –5% Ar stream at 370 C for
2
tion; XCH
out
4
– the theoretical peak’s surface of CH4 which could
1
h and such obtained catalysts were labelled as Red-C-FexSiBEA.
be formed during reaction in the case when all CO is converted to
CH ; X – the theoretical peak’s surface of CO which could be
4
CO2 out
2
2.2. Methods of characterization
formed during reaction in the case when all CO converted to CO2;
XCH – the peak’s surface of CH4 standard when only methane is
s
4
Powder X-ray diffractograms were recorded on a PAN analytical
analyzed; XCO – the peak’s surface of CO2 standard when only
s
2
X’Pert Pro MPD using Cu K␣ radiation (ꢀ = 154.05 pm) in 2ꢁ range
◦
carbon dioxide is analyzed; F – contraction coefficient taken into
account the changes of flow and differences between gaseous sub-
strates and liquid products:
of 5–90 .
The TPR-H2 measurements were carried out in an automatic
◦
TPR system (AMI-1) in the temperature range of 25–900 C, using
−1
H stream (5% H –95% Ar, flow 40 mL min ). H consumption was
SAr i
2
2
2
F = S
monitored by a thermal conductivity detector (TCD).
Thermal analysis data (SETSYS 16/18, Setaram (France) and
mass spectrometer ThermoStar, Balzers (Germany)) were used to
define the formation of carbon deposit.
Ar
s
SAr i–peak’s surface of Ar (inert gas) during reaction; SAr s–peak’s
surface of Ar on inlet before reaction (standard).
The C2 C6 hydrocarbons were not identified during GC analysis.
The selectivity towards liquid products (all formed liquid products)
was calculated from following equation:
◦
The measurements were made in the range of 25–1000 C in
flowing air.
2.3. Catalytic tests
SLP = 100 − (SCH4 + SCO2
)
The FTS catalytic tests were carried out in a fixed bed reactor
using a gas mixture of H2 and CO with molar ratio of 2/1 and
3. Results and discussion
−1
total flow of reagents of 60 mL min . Reaction was carried out
◦
under 30 atm at 340 C and gaseous reagents were analyzed by
3.1. The phase composition of C-FexSiBEA samples – XRD analysis
gas chromatograph (Shimadzu GC-14) equipped with TCD detector
and two columns: measuring – Carbosphere 7A and comparative –
molecular sieves 7B. Parameters of GC measurements: column’s
temperature – 45 C, detector’s temperature – 120 C, detector’s
current – 100 mA; carried gas – He. Before FT reaction, catalysts
The phase composition of prepared samples was studied by
using of XRD method. In Fig. 1 the diffractograms of FexSiBEA zeo-
◦
◦
◦
lites calcined at 500 C for 3 h (x = 4.0, 10 and 20 wt% of Fe) are
shown. The phase analysis was done on the base of JCPD data.
For all studied samples reflexes characteristic of BEA zeolite
were reduced in situ under atmospheric pressure in a flow of 95%
◦
◦
H –5% Ar gas mixture at 370 C for 1 h.
(2ꢁ = 22.52–22.59 ) are identified. This indicates that structure of
2
The liquid products were analyzed by GC–MS coupled tech-
nique. Gas chromatograph was equipped with capillary column
Zebron Phase ZB-1MS order No: 7HG G011-11 and coupled with
quadrupole mass spectrometer. The liquid products in the aim
of water removal, which could be formed during reaction, were
BEA zeolite after iron incorporation and samples calcination is pre-
served. Moreover, this proves that dealumination does not destroy
the BEA zeolite structure and leads to obtain good dispersion of iron
ions in BEA zeolite. The decrease of 2ꢁ value is related to expansion
of BEA matrix and incorporation of part of iron ions into zeolite
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25
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45
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65
75
85
Fig. 3. XRD of Red-C-Fe4.0SiBEA and Red-C-Fe10SiBEA zeolites recorded at room
temperature and ambient atmosphere.
Fig. 1. XRD of C-Fe4.0SiBEA, C-Fe10SiBEA and C-Fe20SiBEA zeolites recorded at room
temperature and ambient atmosphere.
◦
only one TPR peak at 420 C was observed related to reduction
of framework pseudo-tetrahedral Fe(III) to framework pseudo-
tetrahedral Fe(II). The TPR peaks in the third temperature range
◦
between 520 and 650 C observed for all C-Fe4.0SiBEA, C-Fe10SiBEA
and C-Fe20SiBEA zeolite samples may be related to reduction of
Fe O to FeO, in line with literature data [12,13]. The different pos-
3
4
itions of the peaks in TPR-H2 for investigated C-FexSiBEA zeolite
samples are related to different amount of Fe O4 in each sample
3
and the presence of others iron phase what involve some shift of
the TPR peaks in compared TPR profils of C-FexSiBEA samples.
The two mechanism for Fe O3 reduction are postulated (three-
2
step or two-step reduction) in the literature [12,13]:
0
Fe O → Fe O4 → FeO → Fe
(1)
(2)
2
3
3
0
0
Fe O → Fe O4 → Fe or Fe O → FeO → Fe
2
3
3
2
3
The TPR peaks, appeared in the fourth temperature range
◦
between 680 and 730 C for all studied Fe-containing zeolite sam-
◦
ples with maximum at 730, 680 and 710 C for C-Fe4.0SiBEA,
Fig. 2. TPR-H2 profiles of C-Fe4.0SiBEA, C-Fe10SiBEA and C-Fe20SiBEA zeolites.
C-Fe10SiBEA and C-Fe20SiBEA zeolite samples, respectively, are
probably related to reduction of FeO to Fe(0).
framework as pseudo-tetrahedral Fe(III) species, as evidenced by
DR UV–vis data in our earlier report [10].
3.3. Catalytic activity of Red-C-FexSiBEA zeolite samples in
The reflexes assigned to presence of hematite phase were also
observed for all samples. This suggests that iron is present in
FexSiBEA zeolites not only as framework pseudo-tetrahedral Fe(III)
but also as extra-framework octahedral Fe(III) and/or iron oxides,
what is in line with earlier work [10].
Fischer–Tropsch synthesis
The catalytic activity of Red-C-FexSiBEA catalysts were studied
◦
at 340 C under pressure of 30 atm of synthesis gas (CO:H = 1:2)
2
3
−1
and total flow of 60 cm min ). Before catalytic tests the each of
◦
C-FexSiBEA zeolite sample was reduced in situ at 370 C for 1 h in
3
−1
3.2. The reducibility of C-FexSiBEA samples – TPR-H2 studies
hydrogen flow of 40 cm min . The reduction temperature was
chosen on the base of TPR results and the literature reports. Many
scientists suggest that active centre in Fischer–Tropsch synthesis
over Fe catalysts is iron carbide [3], however the functions of these
phases is still considered and ambiguous. Moreover, the iron car-
bide is more active than metallic iron [8]. In Fig. 3 the XRD patterns
The temperature programmed reduction was used to determine
reducibility of iron present in C-FexSiBEA zeolites. The TPR-H pro-
2
files are shown in Fig. 2.
The TPR-H2 patterns indicate different reducibility of various
kinds of iron species present in C-FexSiBEA zeolites and suggest
that reduction of iron is involved in several stages. For C-Fe4.0SiBEA,
C-Fe10SiBEA and C-Fe20SiBEA zeolites the reduction peaks in four
temperature ranges are identified. In the first temperature range
◦
are presented for FexSiBEA samples after reduction at 370 C for 1 h
in hydrogen flow. These results suggest that the reduction of Fe O3
2
is partial. The XRD patterns recorded for samples after reduction at
◦
370 C show presence of the peaks with low intensity, characteris-
◦
a peak at 350–360 C is observed for all C-FexSiBEA zeolite sam-
tic for Fe O3 phase. The main phase observed on diffractograms is
2
ples and could be attributed to reduction of Fe O to Fe O , in line
Fe O , what is in line with TPR-H results (point 3.2.).
3 4 2
2
3
3
4
with our earlier report concerning very similar Fe-containing SiBEA
zeolites [10] and literature data [12,13]. In the second temperature
range, the TPR peaks at 430–480 C are likely related to reduction of
framework pseudo-tetrahedral Fe(III) to pseudo-tetrahedral Fe(II)
identified by DR UV–vis spectroscopy in Fe-containing SiBEA zeo-
lites in our earlier work [10] (not shown here). As shown in [10],
in the Fe-containing SiBEA zeolites with lower than 2 wt% of Fe
In Fig. 4 the CO conversion and selectivity towards CH , CO2
4
and liquid products during FTS carried out on Red-C-FexSiBEA zeo-
lite catalysts are shown. The most active and selective towards
liquid products catalyst is Red-C-Fe20SiBEA, which achieves CO
conversion of 62% and selectivity towards liquid products near of
70% (selectivity towards CH4 and CO2 is of 15 and 16%, respec-
tively). In the case of Red-C-Fe4.0SiBEA and Red-C-Fe10SiBEA, the CO
◦
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Table 1
The quantitative analysis of identified liquid products formed on Red-C-Fe4.0SiBEA, Red-C-Fe10SiBEA and Red-C-Fe20SiBEA zeolite catalysts (calculation done on the basis of
GC-MS data).
Catalyst
Iso-/n-alkanes ratio
(Olefins + iso-olef.)/n-CxH2x+2 ratio
(Alcohols, aldehydes and
ketones)/n-CxH2x+2 ratio
Red-C-Fe4.0SiBEA
Red-C-Fe10SiBEA
1.44
0.30
–
0.029 (ketones only)
0.148 (alc. 0.019; ket.
0.15 (isoolef./olefins: 0.49)
0
.129)
Red-C-Fe20SiBEA
0.87
0.034 (isoolef./olefins:1.33)
0.099 (alc. 0.024;
ald. 0.055; ket. 0.020)
Fig. 4. CO conversion and selectivity towards CH4, CO2 and liquid products formed
◦
during FTS carried out at 340 C for 20 h under pressure of 30 atm on Red-C-
Fe4.0SiBEA, Red-C-Fe10SiBEA and Red-C-Fe20SiBEA zeolite catalysts.
Table 2
The amount of carbon deposition on Spend-Red-C-Fe4.0SiBEA, Spend-Red-C-
Fe10SiBEA and Spend-Red-C-Fe20SiBEA zeolite catalysts (data from TG-DTA
analysis).
Catalysts
Amount of carbon deposition (%)
Red-C-Fe4.0SiBEA
Red-C-Fe10SiBEA
Red-C-Fe20SiBEA
6.7
20.4
35.4
conversion is of 10 and 26% and liquid products selectivity is of 44
and 60%, respectively.
The changes of CO conversion and selectivity towards CH , CO
4
2
and liquid products versus time for Red-C-Fe10SiBEA and Red-C-
Fe20SiBEA are presented in Fig. 5. These results indicate that CO
conversion of both catalysts slightly decreased with increasing of
reaction time. In the case of Red-C-Fe10SiBEA, the CO conversion
changes from 33 to 21% and selectivity towards liquid products
increases from 45 to 60%. In the case of Red-C-Fe20SiBEA, the CO
conversion decreases from 73 to 56% and selectivity towards liquid
products changes from 59 to 71%. Among of the identified by GC-
MS analysis liquid products are n-hydrocarbons, isoalkanes, olefins
and oxidative products. The ratios of isoalkanes to n-alkanes, olefins
and isoolefins to n-alkanes and oxidative products to n-alkanes are
shown in Table 1. For Red-C-Fe4.0SiBEA, mainly isoalkanes is iden-
tified and very small amount of ketones is noted. In the case of
Red-C-Fe10SiBEA, n-alkanes are mainly observed with very small
amount of alcohols and ketones. Similarly, in the case of Red-C-
Fe20SiBEA, the isoalkanes and n-alkanes are identified mainly and
very small amounts of isoolefins, olefins and oxidative products
Fig. 5. CO conversion and selectivity towards CH4, CO2 and liquid products versus
time during FTS carried out at 340 C under pressure of 30 atm on Red-C-Fe4.0SiBEA,
Red-C-Fe10SiBEA and Red-C-Fe20SiBEA zeolite catalysts.
◦
◦
temperature of 600 C. The amount of carbon deposition changes
from 7% for Spent-Red-C-Fe4.0SiBEA to 35% for the most active
Spent-Red-C-Fe20SiBEA catalyst.
In the Table
3 the comparison of catalytic activity in
Fischer–Tropsch synthesis of iron catalysts supported on different
zeolite samples are collected. The tested iron catalysts containing
◦
10 wt% of Fe was carried out at 270 C under pressure of 2 MPa
(19.6 atm). The highest CO conversion and selectivity towards liq-
uid products was found for iron catalysts supported on NaX (48%
of CO conversion and 47.1% of LP selectivity) and NaY (49% of CO
conversion and 48.9% of LP selectivity). Both catalysts showed also
very small selectivity towards CH4 (5.6 and 7.8% for Fe/NaX and
Fe/NaY respectively) [8].
(
alcohols, aldehydes, ketones) are observed (Table 1).
The main reason of deactivation of iron catalysts in
The usually used iron supported catalysts are promoted by
potassium, zinc or cooper and also noble metals in the aim
to improve their catalytic activity in Fischer–Tropsch synthesis
(mainly for increasing of the selectivity towards C5+ hydrocar-
bons). Li and collaborators proved, that doped by potassium iron
catalysts achieved very high selectivity towards liquid products
Fischer–Tropsch synthesis is coke formation. The amounts of
carbon deposition on Spent-Red-FexSiBEA catalysts, calculated
from TG-DTA-MS analysis data, are collected in Table 2. The TG-
DTA-MS analysis, which results are also shown in Fig. 6, indicates
that this kind of carbon deposition on Spent-Red-C-FexSiBEA
catalysts is easily oxidized and its total oxidation occurs below
hydrocarbons of 85–88%, selectivity towards CO of 11.5–20.2% and
2
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Table 3
The comparison of catalytic behaviour of different iron catalysts in Fischer–Tropsch synthesis in similar reaction condition.
Catalysts
CO conv. (%)
Selectivity (%)
CH4
Reaction conditions (T, p, CO:H2 ratio)
Reference
[8]
CO2
C2–C4
LP
◦
Fe/SiO2
22
3.0
29
5.8
48
49
26
62
15
14
12
16
5.6
7.8
22
15
12
19
20
24
30
21
18
16
40
48
35
46
18
23
–
33.2
19
33.2
15
47.1
48.9
60
T = 270
C
Fe/Na-ZSM-5
Fe/Na-MOR
Fe/Na-ß
Fe/NaX
Fe/NaY
p = 2 Mpa
CO:H2 = 1:2
Fe loading 10 wt%
◦
◦
Fe10SiBEA
Fe20SiBEA
T = 340 C p = 30 atm t = 20 h; CO:H2 = 1:2
This work
This work
–
70
T = 340 C; p = 30 atm; t = 20 h; CO:H2 = 1:2
obtained by two-step postsynthesis method are more active than
Fe/Na-ß catalyst what suggests that dealumination of BEA zeolite
and incorporation of iron into framework of BEA zeolite can lead to
improve the activity of BEA zeolite modified by iron in FT reaction.
This allows to consider the Red-C-FexSiBEA zeolites as active and
useful catalysts of Fischer–Tropsch synthesis.
4. Conclusions
The FexSiBEA zeolites with different iron content (4.0, 10 and
0 wt% of Fe) were prepared by two-step postsynthesis method.
The XRD studies showed that in C-FexSiBEA zeolites, the
2
hematite phase reflections have been distinguished beside of
reflections coming from BEA zeolite.
Moreover, these investigations indicated that dealumination
process and incorporation of iron ions into zeolite framework did
not destroy BEA structure.
The TPR-H2 patterns suggest presence of different kinds of iron
species in FexSiBEA zeolites. These TPR-H2 investigations together
with our earlier DR UV–vis studies on similar Fe-containing SiBEA
zeolite allow us to suggest that in C-FexSiBEA zeolites iron is present
as framework pseudo-tetrahedral Fe(III) and extra-framework
octahedral Fe (III) and/or iron oxides.
Catalytic activity tests showed that the Red-C-FexSiBEA
zeolite catalysts can be considered as efficient catalysts of
Fischer–Tropsch synthesis. The most active catalyst was Red-C-
Fe20SiBEA. Some deactivation of Red-C-FexSiBEA zeolite catalysts
during Fischer–Tropsch reaction is probably related to coke forma-
tion.
References
Fig. 6. TG-DTA analysis of Spend-Red-C-Fe10SiBEA and Spend-Red-C-Fe20SiBEA
zeolite catalysts after FTS.
[1] H. Ming, B.G. Baker, Appl. Catal. A 123 (1995) 23–36.
[
[
[
2] M.E. Dry, J. Chem. Technol. Biotechnol. 77 (2002) 43–50.
3] E. de Smit, B.M. Weckhuysen, Chem. Soc. Rev. 37 (2008) 2758–2781.
4] N.E. Tsakoumis, M. Ronning, O. Borg, E. Rytter, A. Holmen, Catal. Today 154
selectivity towards CH4 of 2.0–2.8%, while the CO conversion was
kept at 13–16%. Reaction was carried out under 2.14 MPa (21 atm)
(
2010) 162–182.
[
5] D.H. Chen, H.-T. Lee, J.-I. Yang, H.-J. Kim, J.H. Yang, J.C. Park, B.-K. Kim, H. Jung,
Catal. Lett. 142 (2012) 452–459.
6] Y. Bi, G. Lu, Appl. Catal. B: Environ. 41 (2003) 279–286.
7] A. Corma, J. Catal. 216 (2003) 298–312.
and CO/H ratio was 2.508 [14]. Those catalysts appeared as higher
2
[
[
[
selective towards liquid products that these investigated in our
work presented here, however, it was measured at CO conversion
8] Q. Zhang, J. Kang, Y. Wang, Chem. Cat. Chem. 2 (2010) 1030–1058.
1
3–16%, while our Red-C-FexSiBEA zeolite catalysts are character-
[9] S. Bessel, Appl. Catal. A 96 (1993) 253–268.
10] J. Gurgul, K. Latka, I. Hnat, J. Rynkowski, S. Dzwigaj, Microporous Mesoporous
Mater. 168 (2013) 1–6.
11] S. Dzwigaj, M.J. Peltre, P. Massiani, A. Davidson, M. Che, T. Sen, S. Sivasankar,
Chem. Commun. (1998) 87.
12] W.K. Jozwiak, E. Kaczmarek, T.P. Maniecki, W. Ignaczak, W. Maniukiewicz, Appl.
Catal. A 326 (2007) 17–27.
[
[
[
[
ized by slightly smaller liquid products selectivity of about 70% but
with much higher CO conversion of 70%. Moreover, iron supported
BEA (10 wt% Fe/Na-ß, Table 3) obtained by traditional method
showed very low CO conversion of 5.8%) and selectivity towards
C5–C hydrocarbons of 14%. During FT reaction carried out on these
catalysts the C –C hydrocarbons were mainly formed (selectiv-
9
13] J. Zielinski, I. Zglinicka, L. Znak, Z. Kaszkur, Appl. Catal. A 381 (2010) 191–196.
1
4
[14] S. Li, S. Krishnamoorthy, A. Li, G.D. Meitzner, E. Iglesia, J. Catal. 206 (2002)
02–217.
2
ity towards C -C was of 62%). Our Fe-containing zeolites catalysts
1
4
Please cite this article in press as: K.A. Chalupka, et al., The catalytic activity of Fe-containing SiBEA zeolites in Fischer–Tropsch synthesis,
Catal. Today (2015), http://dx.doi.org/10.1016/j.cattod.2015.02.017