729
while Raman spectra show the presence of ZnCr 2 O 4 phase too. ZnCr 2 O 4 spinel consists of ZnO 4 tetrahedra and CrO 6 octahedra. The close cubic-packed arrangement
of oxide species combines CrO 6 octahedra involving two opposite corners of ZnO 4
tetrahedra. ZnCr 2 O 4 belongs to space group O h
7
. In factor group analysis, one A 1g ,
one E g , and three F 2g Raman active modes are predicted [20, 23]. Raman active band
Fig. 3 Raman 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 . Modes indicated with asterisk mark are due
to Cr 2 O 3 species, while without asterisk mark are due to ZnCr 2 O 4 species
A Sustainable Process for the Synthesis of Alkylpyrazines by Dehydrocyclization…
while Raman spectra show the presence of ZnCr 2 O 4 phase too. ZnCr 2 O 4 spinel consists of ZnO 4 tetrahedra and CrO 6 octahedra. The close cubic-packed arrangement
of oxide species combines CrO 6 octahedra involving two opposite corners of ZnO 4
tetrahedra. ZnCr 2 O 4 belongs to space group O h
7
. In factor group analysis, one A 1g ,
one E g , and three F 2g Raman active modes are predicted [20, 23]. Raman active band
Fig. 3 Raman 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 . Modes indicated with asterisk mark are due
to Cr 2 O 3 species, while without asterisk mark are due to ZnCr 2 O 4 species
A Sustainable Process for the Synthesis of Alkylpyrazines by Dehydrocyclization…