RE2O3-promoted Pt–SO42−/ZrO2–Al2O3 catalyst in n-hexane hydroisomerization

Effects of calcination temperature and water-washing treatment on n-hexane hydroisomerization behavior of Pt-promoted sulfated zirconia based catalysts

“…Signoretto et al [11] also reported the optimal calcination temperature of sulfated Zr(OH) 4 modified with Ga 2 O 3 which depended on the content of Ga 2 O 3 promoter. Our previous results confirmed the important role of rare earth Y promoter in PSZA in the isomerization activity and stability [14]. The investigation from Xia et al [15] demonstrated that the introduction of Al to PSZ could not improve the isomerization activity, but was helpful to catalyst shaping.…”

Alkane isomerization over sulfated zirconia solid acid system

“…Latterly, nickel and/or lanthanum have been used to improve the reactivity of SZ catalysts for n ‐butane, n ‐pentane, and n ‐hexane isomerization . The nickel, palladium, and platinum belong to one family, so many attempts were made on nickel‐modified SZ to replace the noble metal.…”

“…To improve the dispersion of nickel, several researchers employed the rare earth elements as structural and electronic promoters for SZ catalysts . Yu et al reported that the promotion effects of rare‐earth oxides on n ‐hexane isomerization activity decreased as the following order: La 2 O 3 > Yb 2 O 3 > Ce 2 O 3 . Since then, the La has been extensively used as promoter for Ni‐modified SZ catalysts.…”

“…Although having high activity for n ‐alkane isomerization, the SZ catalyst suffers from fast deactivation. Many studies have focused on the deactivation mechanism of SZ in n ‐alkane isomerization, and different deactivation causes have been reported: (a) coverage of active sites by coke and oligomer deposition, (b) removal of surface sulfur as H 2 S under reaction conditions, (c) migration of active sulfur species from the catalyst surface into the bulk zirconia, (d) decrease in the amount and strength of acid sites, (e) crystal transformation of active tetragonal ZrO 2 into inactive monoclinic phase, and (g) reduction of the high valence state sulfur to a lower oxidation state . Our recent study has ruled out the possibilities of the changes in textual properties and zirconia crystallization; that is, the SZ deactivation is caused by a chemical change in the nature of active sites .…”

Catalytic solvent regeneration of a CO2‐loaded MEA solution using an acidic catalyst from industrial rough metatitanic acid

“…Generally, a large specific surface area and large number of acid sites lead to high catalytic activity, and types of acid sites – Lewis acid and Bronsted acid – are also crucial to the catalytic activity . For example, Bronsted acid over the SO 4 2− /ZrO 2 solid acid catalyst plays a key role in the hydroisomerization of n ‐heptane, while strong Lewis acid plays the main role in dehydroisomerization . For the esterification reaction, the catalytic activity of weak acid sites is low, but super strong acid sites catalyze coking and other side reactions, while medium strong acid sites contribute to the esterification reaction …”