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the octahedral Cr species, which are related to vibrations of lattice octahedral groups
[20]. The absorption band around 500 cm
−1
appeared only in catalyst 15ZnO/Cr 2 O 3 ,
thus indicating the presence of ZnCr 2 O 4 phase in this catalyst. The formation of the
ZnCr 2 O 4 phase in the 15ZnO/Cr 2 O 3 sample is further evidenced by the XRD analysis (Fig. 1) of the sample.
3.3 Raman Spectroscopy
Raman spectra of different loadings of ZnO supported on Cr 2 O 3 are reported in
Fig. 3. About seven Raman-active modes, namely, two A 1g and five E g modes, are
due to D 3d point group such as Cr 2 O 3 [21, 22]. XRD analysis showed the presence
of only the Cr 2 O 3 phase in 2ZnO/Cr 2 O 3 , 5ZnO/Cr 2 O 3 , and 7ZnO/Cr 2 O 3 samples,
Fig. 2 FTIR spectra of various loadings of ZnO on Cr 2 O 3 (a) 2ZnO/Cr 2 O 3 , (b) 5ZnO/Cr 2 O 3 , (c)
7ZnO/Cr 2 O 3 , (d) 10ZnO/Cr 2 O 3 , and (e) 15ZnO/Cr 2 O 3
R. Sarkari et al.
the octahedral Cr species, which are related to vibrations of lattice octahedral groups
[20]. The absorption band around 500 cm
−1
appeared only in catalyst 15ZnO/Cr 2 O 3 ,
thus indicating the presence of ZnCr 2 O 4 phase in this catalyst. The formation of the
ZnCr 2 O 4 phase in the 15ZnO/Cr 2 O 3 sample is further evidenced by the XRD analysis (Fig. 1) of the sample.
3.3 Raman Spectroscopy
Raman spectra of different loadings of ZnO supported on Cr 2 O 3 are reported in
Fig. 3. About seven Raman-active modes, namely, two A 1g and five E g modes, are
due to D 3d point group such as Cr 2 O 3 [21, 22]. XRD analysis showed the presence
of only the Cr 2 O 3 phase in 2ZnO/Cr 2 O 3 , 5ZnO/Cr 2 O 3 , and 7ZnO/Cr 2 O 3 samples,
Fig. 2 FTIR spectra of various loadings of ZnO on Cr 2 O 3 (a) 2ZnO/Cr 2 O 3 , (b) 5ZnO/Cr 2 O 3 , (c)
7ZnO/Cr 2 O 3 , (d) 10ZnO/Cr 2 O 3 , and (e) 15ZnO/Cr 2 O 3
R. Sarkari et al.