Highly Loaded Fe MCM-41 Materials: Synthesis and ... - MDPI › data › materials-02-02337-s001 › data › materials-02-02337-s001Figure SI 4 shows that the nature of the precipitating agent has an influence on the structural and textural properties of the 16
Highly Loaded Fe MCM-41 Materials: Synthesis and Reducibility Studies Malose P. Mokhonoana 1 and Neil J. Coville 2,* Figure SI 1. Variation of the lattice parameter (A) and BET surface area (B) with Fe content for the Fe-MCM-41 materials prepared in 1 M HNO3 at 100 °C for 48 h. All samples were calcined at 560 °C for 6 h.
940
47
920
-1
880 860
SBET/m .g
45
2
900
44
42
840 820
43
800 0
2
4
6
8
780
10
0
Fe Content /wt%
2
4
6
8
10
Fe Content /wt%
(A)
(B)
Figure SI 2. The full-range XRD plot of the XRD pattern of the 16 wt% Fe-MCM-41 material synthesized hydrothermally using calcined Si-MCM-41 as a SiO2 source. 400 350 300
Counts/a.u
ao/Angstroms
46
250 200 150 100 50 0 0
10
20
30
40
2-Theta/deg
50
60
70
Figure SI 3. HRTEM micrograph of 3 wt% Fe-MCM-41 prepared at 80 °C for 6 h using water glass as SiO2 source. The material was then calcined at 500 °C for 12 h.
Figure SI 4 shows that the nature of the precipitating agent has an influence on the structural and textural properties of the 16 wt% Fe-MCM-41. The XRD patterns in Figure SI 4 show retention of the mesostructure of MCM-41, together with its long-range order of hexagonal channels. In addition, Fe2O3 peaks appear in the high-angle region of the XRD patterns, which are more intense for NaOH and triethanolamine (TEA) than for Na2CO3. Notably, the metal oxide peaks for the TEA-based material between 20 and 40 °2θ are more intense than the NaOH-based counterpart. These peaks may be related to the reducibility of these materials (see TPR section).
Counts/a.u
Figure SI 4. XRD patterns of 16 wt% Fe-MCM-41 synthesized hydrothermally using the base precipitate route at 100 °C for 2 days. Materials were calcined at 560 °C for 6 h.
NaOH TEA Na2CO3
0
10
20
30
40
2-Theta/deg
50
60
70
Figure SI 5. Variation of the lattice parameter (ao) as a function of Fe loading for FeMCM-41 prepared by incipient wetness impregnation of Si-MCM-41 prepared at 100 °C for 2 days.
Lattice parameter (Angstroms)
50
45
40
35
0
5
10
15
20
25
Fe content (wt%)
Figure SI 6. XRD patterns of Fe-MCM-41 prepared by IWI compared with that of bulk Fe2O3: (a) 16 wt% Fe-MCM-41, (b) 50 wt% Fe-MCM-41 and (c) bulk Fe2O3 (Merck)
Figure SI 7. TPR profiles of (a) 16 wt% Fe-MCM-41 prepared by adding Fe3+(aq) to the Si-MCM-41 synthesis gel 2 h after mixing (but prior to hydrothermal treatment and calcination at 560 °C for 6 h) and (b) bulk Fe2O3.
o
669 C
o
503 C
(b)
(a)
200
300
400
500
600
700
800
o
Temperature/ C Delaying the addition of the water solution of Fe(III) to the mixed water glass/CTAB/H2O gel by 2 h produced a 16 wt% Fe-MCM-41 with some degree of hexagonal order as shown below.
ao = 5.03 nm
80
300 200 110 200
Counts/a.u
400
100
Counts/a.u
500
100
Figure SI 8. Low-angle (left) and high-angle (right) XRD patterns of 16 wt% Fe-MCM41: A water solution of Fe(III) added 2 h after mixing the water glass/CTAB/H2O gel, and the synthesis carried out at 100 °C for 6 h.
100
60 40 20
0
2
4
6
2-Theta/deg
8
10
0
10
20
30
40
50
2-Theta/deg
60
70
Figure SI 9. TPR profiles of 16 wt% Fe-MCM-41 prepared via the OH- route at 100 °C for 5 days: (a) calcined at 450 °C for 12 h, and (b) calcined at 560 °C for 6 h.
o
o
120
120
100
100
o
40
400
600 o
Temperature/ C
60 40
20 200
80
o
60
647 C
H2 Uptake/a.u
80
641 C
H2 Uptake/a.u
413 C
(b) 431 C
(a)
800
20
200
400
600
800
o
Temperature/ C
Table SI 1. A summary of the structural and textural data of the Fe-MCM-41 materials prepared hydrothermally via the OH- precipitate route. Wt% Fe 0 5 10 16 20 a
ao/Åa 47.0 45.3 43.8 44.4 46.2
SBET/m2.g-1 sampleb 930 879 691 546 429
SBET/m2.g-1 supportc 930 926 768 650 536
Error bar is ± 0.6, b Surface area per gram of Fe-MCM-41, c Surface area per gram of Si-MCM-41, i.e., the mass of Fe-MCM-41 corrected for the mass of Fe in the sample to leave only the SiO2 component.
