Vibrational spectra and structure of alkyl gallium derivatives

Characterization for Li3PO4 catalysts toward elucidation of crystalline form and performance relationship

“…To the UC320, deconvolution of spectral bands in the 2780-3060 cm À1 region with Gaussian peaks (R 2 ¼ 0.9920) shows that these alkyl species are identified by four peaks at the following wavenumbers: 2870 cm À1 , 2895 cm À1 , 2930 cm À1 , and 2966 cm À1 (shown in Figure 3 of the supplementary material published online). These bands are possibly attributed to n s ,CH 2 , n s ,CH 3 , n as ,CH 2 and n as ,CH 3 , respectively, based on the literature of Kurbakova et al [22] They are characteristic of alkyl groups on the surface of the catalyst. Alkyl species with three or more carbon atoms in the alkyl chains may also exist in the UC320, as the wavenumber of d,CH 2 , which is in the regions of 1445-1485 cm À1 , overlaps with the vibration frequency of CO 3 2-.…”

Mechanistic insight to acidity effects of Ga/HZSM-5 on its activity for propane aromatization

“…6b, d, f and h, multiple absorption peaks (at about 2886 cm À1 , 2904 cm À1 , 2922 cm À1 , 2967 cm À1 and 2982 cm À1 ) over HZSM-5, Ga/IM, Ga/IMRO1C and Ga/IMRO3C appear in a wide region within 2800-3000 cm À1 when the propane is introduced to the in situ infrared cell in which the catalyst is placed. These peaks are assigned to the adsorbed alkyl species, which are characteristic of ethyl and/or methyl groups bonded to Ga. 37,38 On the other hand, other bands such as 2819 cm À1 , 2844 cm À1 and 2856 cm À1 are probably assigned to the C-H stretching of those alkanes with three or more carbon atoms such as propyl and butyl. 37,38 Therefore, it is plausible that the bands in the 2800-3000 cm À1 region should be assigned to the C-H stretching of propane as well as the intermediates such as methane and ethane.…”

“…These peaks are assigned to the adsorbed alkyl species, which are characteristic of ethyl and/or methyl groups bonded to Ga. 37,38 On the other hand, other bands such as 2819 cm À1 , 2844 cm À1 and 2856 cm À1 are probably assigned to the C-H stretching of those alkanes with three or more carbon atoms such as propyl and butyl. 37,38 Therefore, it is plausible that the bands in the 2800-3000 cm À1 region should be assigned to the C-H stretching of propane as well as the intermediates such as methane and ethane. Simultaneously, it can be observed that the intensity of these peaks (at about 2886 cm À1 , 2904 cm À1 , 2922 cm À1 , 2967 cm À1 and 2982 cm À1 ) over HZSM-5, Ga/IM, Ga/ IMRO1C and Ga/IMRO3C rst increases with enhanced temperature until about 125 C and then decreases as a function of temperature (this is also observed based on the proles of the peak intensity as a function of temperature in Fig.…”