IR study of active sites for n-heptane isomerization over MoO3-ZrO2

Isomerization of linear C5–C7 over Pt loaded on protonated fibrous silica@Y zeolite (Pt/HSi@Y)

“…4 (c) shows IR spectra for Pt/HSi@Y outgassing of pyridine at elevated temperatures from 423 to 623 K. Upon increasing the outgassing temperature, pyridine molecules adsorbed on weak acid sites will be desorbed at lower temperatures and pyridine molecules adsorbed on strong acid sites will be desorbed at higher temperatures [16] . The results showed that all types of catalysts possessed Lewis and Brønsted acid sites after outgassing of adsorbed pyridine at 573 K. This indicates that Pt/HSi@Y type catalysts possess relatively weak and strong acid sites [32] .…”

C5–C7 linear alkane hydroisomerization over MoO3–ZrO2 and Pt/MoO3–ZrO2 catalysts

“…3B shows the variations of the IR spectra as a function of outgassing temperature after pyridine adsorption for the sample activated at 573 K. If the outgassing temperature is raised, pyridine molecules adsorbed on weak acid sites should be desorbed at lower temperatures, and those adsorbed on strong acid sites should be desorbed at higher temperatures. For MoO 3 -ZrO 2 , both Brønsted and Lewis acid sites decreased significantly with outgassing temperature indicating the wide distribution of both acidic sites on the MoO 3 -ZrO 2 sample [23]. It should be noted that the decrease was extensively observed for Lewis acid sites than that of Brønsted acid sites.…”

“…Results and discussion [23,29]. No intensity corresponds to the reflections of Pt (1 1 1), which should appear at 2h = 40°, was observed in the XRD pattern of Pt/MoO 3 -ZrO 2 .…”

“…We have previously reported the acidic properties of MoO 3 -ZrO 2 , in relation to the active sites which participate in the formation of active protonic acid sites from molecular hydrogen that favor in nheptane isomerization [23,24]. Although it has also been reported widely that the introduction of Pt site is able to improve the activity and stability of zeolites, alumina, WO 3 -ZrO 2 , and SO 2À 4 -ZrO 2 , there is almost no report related to the study of Pt loaded on MoO 3 -ZrO 2 for hydroisomerization of alkanes in the literature.…”

Influence of Molybdenum Loadings on the Properties of MoO3/Zirconia Catalysts

“…Reddy et al [23], recommended further studies to determine the exact nature of the acid sites present on molybdenum zirconia and other oxides. Ruslan et al [25] concluded that introduction of MoO 3 on ZrO 2 partially eliminated the absorbance band at 1605 cm −1 ascribed to Lewis acid sites corresponding to the presence of the monoclinic phase of ZrO 2 and developed several Bronsted and Lewis acid sites with different acidic strengths. MoO 3 -ZrO 2 possesses a large number of relatively weak Lewis and Bronsted acid sites as well as strong acid sites.…”