FT-IR Studies on Light Olefin Skeletal Isomerization Catalysis

On the surface sites of MoP/SiO2 catalyst under sulfiding conditions: IR spectroscopy and catalytic reactivity studies

“…2055 cm −1 can still be distinguished for the sample treated at 673 K. The appearance of the band at 2100 cm −1 indicates the sulfidation of the phosphide surface because this is a characteristic band of CO adsorbed on sulfided Mo catalyst and has been assigned to linearly adsorbed CO on cus Mo 2+ sites [21,23,27]. The results show that the surface of the MoP/SiO 2 catalyst is partially sulfided when treated with the thiophene/H 2 mixture at 673 K. A separate detection of the changes of thiophene itself during the treatments at different temperatures shows that thiophene becomes reactive with hydrogen on the MoP/SiO 2 catalyst at and above 373 K. Thus, the gradual sulfidation of MoP/SiO 2 catalysts can be ascribed to the HDS of thiophene [31][32][33][34]. Fig.…”

Decomposition of styrene dimers on Al2O3–Cr and Al2O3–SiO2–Cr catalysts of acid and redox nature

“…The reactions leading to the formation of indane, indene and naphthalene derivatives do not take place since strong protic sites able to protonate the aromatic ring are necessary for their initiation. The probability of such reaction mechanism is further supported by the observation that alumina, generally presumed to possess Lewis acid and weak Brønsted acid centers [18], transforms 2-butene to alkoxy species at elevated temperatures ([473 K) [19].…”

The role of butylbenzene carbenium ions in the acid catalyzed cracking of polystyrene. Transformation of n-butylbenzene, sec-butylbenzene, iso-butylbenzene, tert-butylbenzene, 4-phenyl-1-butene, n-propylbenzene and n-hexylbenzene over silicaalumina and alumina acid catalysts

“…It is believed that Brønsted acid centers (bridged type groups Al-OH-Si) [16] are responsible for the activity of silicaaluminas, while Lewis sites (Al 3? cations) and OH groups activated by adjacent Lewis centers [17] sites of alumina is much lower than those of silicaalumina and zeolites but higher than for SiO 2 [16,17]. The results of pyridine adsorption followed by FTIR measurements (Fig.…”